WO2006008155A1 - Analysis of rock formations by means of laser induced plasma spectroscopy - Google Patents

Analysis of rock formations by means of laser induced plasma spectroscopy Download PDF

Info

Publication number
WO2006008155A1
WO2006008155A1 PCT/EP2005/007931 EP2005007931W WO2006008155A1 WO 2006008155 A1 WO2006008155 A1 WO 2006008155A1 EP 2005007931 W EP2005007931 W EP 2005007931W WO 2006008155 A1 WO2006008155 A1 WO 2006008155A1
Authority
WO
WIPO (PCT)
Prior art keywords
outer housing
point
plasma
laser
light
Prior art date
Application number
PCT/EP2005/007931
Other languages
French (fr)
Inventor
Soeren Lund Jensen
Thomas Steenberg
Original Assignee
Scandinavian Highlands A/S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Scandinavian Highlands A/S filed Critical Scandinavian Highlands A/S
Priority to AU2005263614A priority Critical patent/AU2005263614B9/en
Priority to CA002574867A priority patent/CA2574867A1/en
Priority to EP05788676A priority patent/EP1779095A1/en
Publication of WO2006008155A1 publication Critical patent/WO2006008155A1/en

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/71Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
    • G01N21/718Laser microanalysis, i.e. with formation of sample plasma
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B49/00Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells

Definitions

  • the invention relates to methods of chemical analysis of chemically heterogeneous rock formations, for instance in the course of exploration or mining operations, comprising determining a chemical analysis of a man-made surface in the rock formation.
  • the invention also relates to devices which are adapted for use in such methods .
  • ores such as sulphide ores (for example copper, lead and zinc) , oxide ores (for example aluminum, chromium, vanadium, iron, titanium or manganese) or metallic alloy ores (for example silver, gold, platinum group metals) .
  • sulphide ores for example copper, lead and zinc
  • oxide ores for example aluminum, chromium, vanadium, iron, titanium or manganese
  • metallic alloy ores for example silver, gold, platinum group metals
  • the concentrations of minerals are often heterogeneous. That is, the concentration of mineral varies significantly in different regions of the formation.
  • the mineral may be found in very high or very low concentrations and may even be absent from some regions.
  • minerals often comprise grains or crystallites or crystals with varying chemical compositions and the average chemical composition of the ore varies with position in the mineralisation.
  • One option is to take samples from positions within the removed material that are very close together, which can lead to an accurate determination of the composition of the surface but is very lengthy and costly. It is also inefficient because the ore could be completely absent from a large proportion of the sampled surface.
  • X-ray fluorescence X-ray fluorescence
  • AAS X-ray fluorescence
  • ICP X-ray fluorescence
  • neutron activation X-ray fluorescence
  • none of these methods can provide reliable quantitative in-situ analysis because of the need for sample preparation. Relatively long return times also limit the use of these analytical methods.
  • the apparatus used in methods involving XRF is large and can not be used in typical holes .
  • the invention aims to provide a method of chemical analysis which is adapted for use in analysis of chemically heterogeneous rock formations and which can be used in-situ to determine efficiently and in real time the location, distribution and concentration of a mineral in a rock formation.
  • the invention provides, in a first aspect, a method of spatial analysis of a chemically heterogeneous rock formation, comprising determining a chemical analysis of a man-made surface of the rock formation, the method comprising the steps of : providing the man-made surface; providing a device which is adapted to emit a beam of laser light so as to generate a plasma at a first point on the surface, and a light collector; taking a first measurement by generating a plasma at the first point, collecting light from the plasma with the light collector, transmitting it to a spectrophotometer and determining a chemical analysis of the surface at the first point.
  • a second aspect of the invention provides an apparatus for use in carrying out spatial analysis of a chemically heterogeneous rock formation, the apparatus comprising: (a) a laser which is adapted to generate a beam of laser light;
  • a device adapted to emit a beam of laser light and comprising (i) a focus means adapted to focus the laser light before emission so that a plasma is generated at a surface adjacent the device, (ii) a light collector positioned so as to collect light from the plasma, (iii) an outer housing containing the focus means and the light collector,
  • the device which is the part of the apparatus which emits the laser light is a third aspect of the invention.
  • the invention uses laser induced plasma spectroscopy (LIPS) to carry out chemical analysis.
  • LIPS laser induced plasma spectroscopy
  • the invention has many advantages, especially in a mining or exploration operation. For instance, no sample removal from the rock formation is required and thus minimal or no sample preparation is needed and there are no special requirements as to the state of the sample surface (in particular porosity, whether the surface is wet or dry) . In some cases it may be advantageous to remove dust or mud from the surface before taking measurements but no other special preparation is required. In addition, there is no need for provision of a special atmosphere such as inert gas, a vacuum or dry air.
  • the ability to analyse without removing samples from the surface greatly increases the accuracy of determining the distribution of the ore mineral within the formation and further facilitates spatial analysis
  • LIPS can give real-time analysis meaning that the time between operating the laser and analysing the composition of the rock surface is less than 60 minutes, usually less than 30 minutes and can be below 15 minutes or 5 minutes but is most preferably between 30 seconds and 1 minute.
  • the device, apparatus and methods of analysis of the invention are advantageous in the mining industry as they are particularly adapted for use in relatively narrow openings having high length to diameter ratio
  • the invention allows determination of the chemical analysis of the inner surfaces of drilled holes in rock formations.
  • LIPS has been used in the past with respect to analysis of soil (which is rather soft in comparison with rock formations, and in which mobility of elements is generally greater than in rocks) , in particular to determine the level of contamination of soil (see US Department of Defense Environmental Security Technology Certification Program published April 2003) .
  • LIPS may also have been used for exploration methods but only for rather homogeneous rock faces and not in such a manner as to generate a spatial analysis .
  • rock formations which have hard surfaces .
  • the rock is generally consolidated sedimentary rock or igneous rock.
  • the man-made surface can be made by grinding, drilling, sawing, ploughing, blasting, hammering or by fracturing caused by man-made explosions or tensions .
  • the invention is particularly useful for analysis of openings with relatively high ratio of length to diameter, as it is particularly difficult to analyse these accurately and efficiently using conventional methods.
  • openings are: holes used for pre- extraction exploration and prospecting of metals or minerals, where the depth is usually 0.1 to 1000 meters but can be up to 1500m and the diameter is 1 to 70 cm at the narrowest point; holes used for blasting in the mining industry, where the depth of the hole is usually 0.1 to 50 meters and the diameter at the narrowest point is 1 to 20 cm,- and channels made by sawing or grinding the surface of a rock formation used for pre-extraction exploration and prospecting of metals or minerals, where the depth of the channel is usually 1 to 100 centimetres and the width at the narrowest point is 0.1 to 10 centimetres.
  • the depth of the opening is preferably between 0.1 - and 1000m and the width of the opening at the narrowest point is preferably between 1 and 100cm, more preferably 1.5 and 50cm, most preferably 1.5 and 16cm.
  • the opening in the rock formation has a diameter which is not more than 200% of the diameter of the device.
  • the invention makes use of the known laser induced plasma spectroscopy (LIPS) technique for chemical analysis.
  • LIPS laser induced plasma spectroscopy
  • chemical analysis we mean the obtaining of information about the presence (qualitative) or amount, absolute or relative (quantitative) ,of one or more chemical elements. For instance, the presence of a single element can be detected, or the ratio (s) between two (or more) elements, or the amount of one or more elements .
  • the LIPS technique uses a pulsed laser to generate a laser spark which rapidly heats a sample causing vaporization, dissociation into atomic species, and ionisation, which produces a plasma. As the plasma cools, the excited species relax and emit optical energy at characteristic wavelengths. The emission can be spectrally resolved to identify the elemental species that are present in the sample based on the presence of characteristic spectral lines. The concentration of the elemental species present may be proportional to the intensity of the spectral lines produced or, if it is not proportional, may be calculated by descent calibration.
  • the invention does not require any specific type of LIPS, meaning that any suitable type of laser, duration of laser pulse, type of detector or spectrophotometer to resolve the emitted energy, etc. can be used.
  • the plasma can be generated using repetitive single spark laser pulses or repetitive double spark laser pulses.
  • pulsed lasers are Nd:YAG and Excimer lasers.
  • a Nd:YAG laser is used with 532 or 1054nm wavelength.
  • Laser pulse duration can range from femtosecond laser pulses to 50 nanoseconds.
  • Pulse energy can be from 5 mJ upward, for instance up to around 25OmJ and is preferably 20 to 50 mJ.
  • Pulse frequency can be from 1 Hz but is typically from 5 Hz upwards, for instance up to about 50 Hz and is preferably between 10 and 50 Hz, most preferably about 20 Hz.
  • LIPS can be used both as a quantitative and qualitative analytical method for chemical analysis. Entire spectra can be analysed in order to make a quantitative chemical analysis. Alternatively only a narrow part of the spectrum can be analysed in order to gain qualitative information about the presence of a single component, a selection of components, ratio between components or combinations thereof.
  • the analysis involves taking a measurement by generating a plasma at a point, collecting light from the plasma with the light collector, transmitting it to a spectrophotometer and determining a chemical analysis of the rock at the point on the surface.
  • the laser beam is generated by a laser.
  • the beam of laser light is emitted from the device which is adjacent the surface.
  • the laser may form part of the device. Alternatively, it may be positioned away from the rock surface being analysed and connected to the device by light guidance means which transmit the laser light to the device. Examples include optical fibres.
  • the device comprises a focus means which focuses the laser light.
  • the focused light is emitted from the device and generates a plasma at the surface.
  • the focus point of the laser beam may be at or slightly behind the surface.
  • the invention requires collecting the light generated by relaxation of the species in the plasma.
  • the light collector is a lens and the collected light is transmitted to the spectrophotometer by light guidance means, such as optical fibres.
  • the LIPS technique uses a spectrophotometer as a means of analysing the light from the plasma.
  • the spectrophotometer can be any suitable type. Preferably an Echelle spectrograph is used.
  • the spectrophotometer is located away from the surface to be analysed.
  • the invention generally also uses a detector such as a CCD or ICCD (intensified CCD) .
  • the data from the spectrophotometer should be translated into a chemical analysis by using suitable software provided, for example provided in a PC.
  • the spectrophotometer may have an input into a user- interface or a feedback system.
  • the detector is positioned between the spectrophotometer and the • analysis software. The detector transmits the data from the spectrophotometer to the software and can store information from the spectrophotometer.
  • the invention provides spatial analysis of the chemical content of the rock formation. That is, it provides a determination of the variation of the chemical analysis over a region of the rock formation. To achieve this, the method requires that measurements are taken at at least two different points on the man- made surface, and preferably at least 10, more preferably at least 100 points and usually even more.
  • the apparatus used in the invention includes a movement control system which moves the point at which the plasma is generated relative to the rock surface.
  • the chemical analysis of the surface can be made along the length direction of openings such as holes, cores or tracks in order to describe features of the chemical composition and variations thereof. Alternatively a number of spots within an area, around the perimeter of an opening or at the edge of a track can be analysed in order to establish features of the chemical composition at a certain position.
  • the movement control system is used to move the device to enable measurements to be taken at different points on the surface.
  • the device usually includes an outer housing so that the point at which the plasma is generated is adjacent to the outer housing.
  • the movement control system moves the outer housing relative to the rock surface. This is particularly useful when the device is carrying out a scanning operation (as discussed below) .
  • the movement control system moves the point at which the plasma is generated relative to the outer housing. This is a fine movement and can be used during a more detailed analysis of the surface. This allows the point at which the plasma is generated to be moved without moving the outer housing of the device itself.
  • the movement control system can be any suitable design, for instance using a spindle to achieve movement of the point at which the plasma is generated relative to the outer housing.
  • the movement controller includes control software which can be operated by a user distant from the device and the surface to be analysed.
  • the device preferably comprises an outer housing which is preferably made of plastic, metal, ox any material which is rigid and strong enough to withstand any accidental knocks against the surface. Examples are stainless steel, Inconel ® , bronze and titanium.
  • the outer housing usually has an opening or window through which the laser beam can be emitted from the device.
  • the outer housing is preferably an inner housing which is typically made of a plastic or metal material .
  • the inner housing also usually has an opening or window in it through which the laser beam can pass.
  • the laser is generally located within the inner housing, preferably in a fixed position relative to the inner housing.
  • the inner housing is moveable relative to the outer housing. This is typically achieved by use of the movement control system.
  • the outer housing and the inner housing can each be pressurised in order to prevent dust from entering the device.
  • the windows in the inner and outer housing can be covered in glass through which the laser'beam can pass, to prevent and debris evtering the housing.
  • the glass is usually spherical.
  • the device may contain an air nozzle or vent to blow away dust from the point to be analysed.
  • the device preferably includes a positioner which is adapted to maintain a predetermined distance between the outer housing and a rock surface.
  • the positioner is preferably one or more spacers which are connected to the outer housing and which maintain a predetermined distance between the outer housing and the rock surface.
  • the device preferably includes at least two spacers.
  • the device has a longitudinal axis and longitudinal sides substantially parallel to the longitudinal axis.
  • At least one spacer can be resiliently biased so as to create a force holding the device against the inner surface of an opening in a rock formation.
  • the hole can be of a size predetermined to be of diameter slightly greater than that of the device, so that there is no need for spacers.
  • the spacers can be made of any suitable material which is capable of withstanding handling and possible impact on a rock surface.
  • the device When the device is in use, it preferably moves across the rock surface in a direction parallel to its longitudinal axis.
  • the point at which the plasma is generated also moves in a direction parallel to the longitudinal axis of the device.
  • the point at which the plasma is generated can be moved so that it rotates about the longitudinal axis of the device. This latter option is particularly useful when the surface is a drilled hole.
  • the rock surface comprises sulphide minerals, oxide minerals or metallic alloys.
  • the method of the invention is particularly useful when the mineral and/or the ore is invisible with the naked eye. This is often the case for precious metals such as gold and platinum group elements. The need for chemical analysis and in particular accurately and efficiently targeted chemical analysis increases if the mineral and/or ore is not visible to the naked eye.
  • the invention is also particularly useful when the concentration of the mineral in the rock is low.
  • the invention is particularly useful when the mineral forms less than 50% of the composition of the rock, preferably less than 20%, more preferably less than 10% and most preferably less than 1%.
  • the invention is suitable for use in mining in a rock formation in which there is a heterogeneous (non- continuous) distribution of elements to be analysed.
  • the invention is particularly useful for mining and exploration activities related to platinum group metals, gold, silver, zinc, copper, vanadium, nickel, chromium, cobalt, titanium, lead, niobium, molybdenum, tantalum, tungsten, tin, antimony, bismuth and rare earth elements (and combinations thereof) .
  • the invention is particularly useful for precious metals, for example platinum group metals, gold and silver, because these precious metals are very high in value.
  • the invention is also useful in diamond mining or exploration as diamonds are known to be associated with certain mineral compositions.
  • the most common mineral compositions indicating a higher possibility of the presence of diamonds are, olivine (Fe/Mg) where the iron to magnesium ratio is important, ilmenite (Fe/Ti) the iron to titanium ratio is important and garnet (Cr, Mg, Ca, Fe) where the content and ratios are also important.
  • the invention is useful in exploration methods These include searching for deposits of useful minerals and in establishing the nature of a known mineral deposit, preparatory to development. It may also be used during mining operations, that is processes of extracting mineral deposits from rock formations.
  • the invention can also be useful in oil exploration and drilling.
  • the size of a spot analysed using LIPS can have a volume of approximately 1 ⁇ m 3 but may have a much larger volume, of between 0.05 and 0.2 mm , preferably around 0.1mm . This is typically smaller than a grain or crystallite in a mineral.
  • an average must be taken from a number of measurements to get an accurate result .
  • the average should be taken from a large number of measurements (over 100) from a small area (of about 100 cm 2 ) to give a very accurate reading. Over a large surface, this can be very slow.
  • the heterogeneous distribution of rock formations generally means that the distance between grains, inclusions and/or crystallites is typically between 10 and 10000 times higher than the size of the plasma generated by LIPS.
  • the apparatus and the method of the invention allow for inclusion of a feedback system. This can be used in conjunction with the movement controller to determine the movement of the device over the surface . Measurements can then be taken at points along the surface.
  • the feedback system also allows for analysis to be done in stages of increasing accuracy so that detailed analysis of the entire surface is not necessarily carried out . A scanning stage can be used to identify areas likely to contain the ore and then subsequent stages concentrate the analysis to determine the concentration of the ore and mineral in these areas. Hence, the efficiency can be greatly improved.
  • the apparatus and device of the invention preferably comprise a feedback system which is adapted to control the movement controller- in accordance with input from the spectrophotometer.
  • the input is produced using the information obtained from the spectrophotometer when its signal has been processed.
  • the feedback system of the invention ensures efficiency and quality of the chemical analysis .
  • the feedback system can determine the speed of the device relative to the surface of the sample, the number of points to be analysed, the position of the points and the number of measurements to be taken at each point.
  • the aim of this system is to identify areas where the ore is present by making a highly reduced number of measurements as compared to a detailed analysis of the chemical compositions with high spatial resolution along the length of the surface.
  • the feedback system can also make use of conventional statistical methods for geological exploration and sampling such as semi-variogram and Kriging or the use of an optical system for visual inspection of the sample surface or the use of a reduced number of measurements combined with conventional statistical methods or the use of knowledge obtained from pre-exploration studies and geology in general or combinations thereof.
  • a preferred method involves the device being used to analyse features of the composition of the surface in a number of stages.
  • the method additionally uses a feedback system which controls the movement of the device in accordance with input from the information obtained from the spectrophotometer and wherein the method additionally comprises the steps of; scanning by moving the point at which the plasma is generated over the surface and taking measurements at predetermined scan points; using the feedback system to compare the chemical analysis at the scan points with predetermined criteria, selecting a number of sample areas on the surface where the chemical meets predetermined criteria, and within each- sample area; moving the point at which the plasma is generated over the surface within the sample area, and taking measurements at predetermined fine measurement points.
  • the first step is typically scanning. This involves moving the device over a macroscopic area and taking measurements at scan points to identify the types of minerals that are present in the rock.
  • the scan points are preferably between 0.1 and 1 m from each other.
  • main mineral phases of the rock can be identified, for example whether the rock comprises carbonate, quartz, feldspar, amphibole etc.
  • the results are then compared by the feedback system with predetermined criteria, for example, if the mineral is associated with a sulphide phase the feedback system will ""choose ' ' sample areas which comprise a sulphide phase to undergo subsequent more detailed analysis.
  • the aim is to determine the general type of the rock rather than accurate levels of particular elements. Therefore, the detection limit does not need to be particularly ' high compared to later analytical stages and a smaller number of measurements
  • the sample area chosen varies according to the nature of the mineralization. However, a typical width is between 0.01 and 1 m. The sample area is significantly larger than the typical size of grains or crystals .
  • the next stage typically is a more detailed analysis or fine measurement within each sample area.
  • a number of measurements on a microscopic scale are carried out at fine measurement points on the surface. This means that the fine measurement points are between 0.5 and 1000 ⁇ m from each other, preferably between 1 and 50 ⁇ m from each other.
  • the fine measurement points should be spaced throughout the sample area to ensure that the measurements are made on a large number of different crystals. This enables an accurate result to be obtained.
  • the feedback system works by taking an average of a number of measurements at the fine measurement points to get an accurate determination of the overall chemical analysis within each sample area.
  • the detection limit of the device typically many measurements or spectra are taken at each fine measurement point. This allows taking into account the background noise in the spectra and to ensure that the spectrophotometer can pick up a low level of the mineral.
  • the detection limit should be below lOOppm, preferably below 50ppm. To achieve this, typically more than 100, preferably more then 200, most preferably more than 300 measurements are taken at each fine measurement point .
  • analytic techniques can be used in combination with LIPS, for example an optical system for ' visual inspection of the sample surface.
  • Other suitable techniques include geophysical methods such as magnetic field measurements (eg Fluxgate magnetometer) , inclination sensor (accelerometer) , electrical resistance measurements, acoustic methods and radiation detection devices.
  • Figure 1 shows a cross section through a device according to a preferred embodiment of the present invention.
  • Figure 2 shows a device according to a preferred embodiment of the present invention.
  • the Figures both show a device (21) within a man- made hole drilled in a rock formation (20) .
  • the device is adjacent to the inner surface (1) of the hole.
  • the device has outer housing (2) with spacers (4) attached to it .
  • the spacers are located above and below the opening (3) in the outer housing (2) through which the laser beam is emitted.
  • the spacers (4) maintain a predetermined distance between the outer housing (2) and the rock surface (1) .
  • the spacers (4) on the opposite side of the housing have a bias mechanism (5) . This ensures that the spacers on the opposite side of the housing from the opening (3) are in contact with the surface of the hole.
  • the device comprises an inner housing (6) in which the laser (8) is located. The inner housing can be moved with respect to the outer housing by means of one aspect of the movement controller (7) .
  • the device comprises an optical system (11) and a lens (10) which directs the laser beam through an opening . (12) in the inner housing (6) and the opening (3) in the outer housing (2) .
  • windows rather than openings are present in both the inner and the outer housing through which the laser beam can pass.
  • the laser beam is directed at the rock surface (1) and the optical system (11) , lens (10) , laser (8) and outer housing (2) are positioned so that the focus point of the laser beam is at or behind the surface.
  • the device also comprises a light collector (9) which, in this case, is an optical fibre and is positioned so that it can collect light from the plasma generated by the laser at the surface.
  • the device includes a sealing means (14) which prevents dust from entering the space between the inner and outer housing.
  • the device includes a power cord (15) which supplies power to the parts of the device that need it such as the laser (8) and the fine movement controller (7) .
  • a cable (17) is shown in Figure 1 which is part of a movement controller and moves the device relative to the rock surface.
  • Signal wire (16) is a part of the feedback system and relays information about the location of the device relative to the surface and the location of the point at which the plasma is generated.
  • the spectrophotometer (23) is located, in this embodiment, on the ground outside the hole.
  • the movement controller (24) is located above the hole and a user interface (22) is located above the hole and the feedback system can be controlled from here.
  • the movement controller can also be controlled from the user interface and the results of the chemical analysis from the spectrophotometer can be reviewed via the user interface.
  • Example 1 The method of the invention is used in the investigation of a mineralisation of platinum in chromite present in pyroxenite. The platinum is known to be located in a sulphide phase in the chromite .
  • the sulphide content in the chromite is known to be between 0 and 5% and the sulphide phase typically contains 0 to 100 ppm platinum.
  • a minimum average concentration of 1 ppm platinum is required for a profitable mining operation in this location.
  • the presence of chromium, magnesium, aluminium and silicon indicate a pyroxenite mineral.
  • a hole which is 500 meters long is made in the rock formation by grinding.
  • the information relating to the hole, the mineral and ore and feasible concentrations is fed into the feedback system via the user-interface.
  • the inner surface of this hole is analysed by a method of the invention.
  • the surface is divided into 1 meter segments along the length to give a total of 500 segments.
  • a reasonably accurate determination of the concentration of chromium, magnesium, aluminium and silicon is achieved by taking 200 measurements per segment (i.e. having scan points every 0.5 cm) . One measurement per scan point is taken.
  • a 10 Hz pulsed laser is used which takes 10 measurements per second and the device has a speed of 5 cm/s relative to the sample surface.
  • the scanning operation has a duration of approx. 3 hours.
  • the next step is the positioning of a number of sample areas within the chromite-containing phase is such way that the results of the measurements in these positions results in a meaningful description of the phase.
  • the feedback system will often position a number of sample areas equidistantly over the phase of interest. In this case 10 sample areas with a length of 10 cm and a width of 10 cm are positioned equidistantly over the 50 meters of the pyroxenite phase.
  • the size of the sample area is significant larger than the size of the grains or crystals on the surface to ensure that the fine measurement points within the sample area hit a high number of different grains or crystals (a high number of fine measurement points on the same grain or crystal would not result in the average chemical analysis within that sample area) .
  • the number of fine measurement points that should be analysed within each sample area depends on the required accuracy. In this case 150 fine measurement points are analysed within each sample area and the fine measurement points are positioned equidistantly within the sample area.
  • the 200 plasma are created at each fine point to give a detection limit below 50 ppm.
  • the detector creates a spectra from the 200 measurements which has. a very high level of accuracy.
  • the average chemical composition within the sample area is calculated from the results from the 150 fine measurement points analysed.
  • the results from one sample area are 1 fine measurement point with 80 ppm platinum, 1 fine measurement point with 60 ppm platinum, 1 fine measurement point with 50 ppm platinum, 1 fine measurement point with 40 ppm platinum, and 146 fine measurement points with no platinum (or a platinum content below the detection limit) .
  • Example 2 In this example a method of the invention is used to investigate the spatial concentration of platinum from example 1. This example additionally involves use of an optical feedback system.
  • the presence and position of the sulphide within the pyroxenite is investigated using an optical system.
  • a system consists of a source of light with a wavelength that is mainly reflected by the sulphide phase and not by the pyroxenite. This reflection is used to direct the device to the sulphide phase and is a very efficient way to clarify whether the sulphide phase is present and if it contains any platinum.
  • Example 3 In this example a method according to the invention including a feedback system is used in the investigation of the spatial concentration of gold in a blasting hole in a mining operation.
  • a minimum concentration of 2 ppm gold is required for a profitable mining operation in this location.
  • the aim of the investigation is to ensure that only rocks with a gold content of minimum 2 ppm are released at the blasting.
  • the blasting hole in this example is 3 meters deep and it is thought to be possible that the gold content drops below 2 ppm at a certain depth within the hole.
  • This information is entered into the feedback system. No information about the distribution or grain size is- available. In this case it is important to minimise the standard deviation of the calculated gold content .
  • a sufficiently high number of fine measurement points need to be analysed within each sample area. Only 20 spectra are taken at each fine measurement point, as gold is most often located in grains with a fairly high gold content. The number of fine measurement points is chosen to be 1000 and the size of the sample area is 4 cm by 10 cm (width by length) . The analysis of each sample area takes approx. 35 minutes when the 10 Hz pulsed laser is used.
  • the feedback system is used to evaluate whether 1000 fine scan points within a sample area results in a sufficiently accurate determination of the gold content within that area.
  • the first sample area is positioned at the bottom of the hole (i.e. at a depth of 3 meters) . If the result showed a gold content above 2 ppm no further analysis is needed and the explosives can be positioned at the bottom of the blasting hole. If the gold content is found to be 1.0 ppm at the bottom of the hole, the next sample area is positioned 1 meter from the bottom (i.e. at a depth of 2 meters) .
  • the gold content is 1.8 ppm, in this case one can assume a linear variation in the gold content and use linear extrapolation and estimate that the gold content should be above 2 ppm at a depth of 1.75 meters
  • the bottom 1.25 meters of the blasting hole could then be closed (e.g. by a solid stick made from wood) and the explosives positioned at a depth of 1.75 meters.
  • the sample area is positioned at a depth of 1.75 meters in order to verify that the gold content is above 2 ppm.
  • the results are compared with other nearby blasting holes in order to evaluate whether the results seem reasonable. If one blasting hole showing a gold content of 2 ppm at a depth of 3 meters is surrounded by blasting holes showing no gold at a depth of 3 meters, then the result showing 2 ppm is likely a faulty measurement, and is repeated.
  • This example relates to the investigation of the concentration of platinum in an exploration hole in relation to an ""invisible ore 1 ' type of mineralisation. This means that the ore is not visible to the naked eye.
  • the platinum content is related to the ratio between cobalt and nickel.
  • a scanning stage has been carried out and it is known that the cobalt and- nickel are uniformly distributed within the sample and the concentration is 0 to 100 ppm.
  • An atomic cobalt/nickel-ratio > 2.5 indicates a platinum content above 1 ppm.
  • the sample areas are positioned at 1 meter intervals. Each sample area is analysed at 20 fine measurement points and 200 spectra are taken at each fine measurement point to have a sufficiently low detection limit for cobalt and nickel. Using 10 Hz laser pulses (i.e. 10 spectra measured per second) , the time for analysing each sample area is

Abstract

The invention relates to methods of chemical analysis of chemically heterogeneous rock formations, for instance in the course of exploration or mining operations, comprising determining a chemical analysis of a man-made surface in the rock formation. The invention also relates to devices which are adapted for use in such methods. The invention uses laser induced plasma spectroscopy (LIPS) to carry out chemical analysis.

Description

AWALYSIS OF ROCK FORMATIONS BY MEAWS OF LASER IWDUCED PLASMA SPECTROSCOPY
Field of the Invention
The invention relates to methods of chemical analysis of chemically heterogeneous rock formations, for instance in the course of exploration or mining operations, comprising determining a chemical analysis of a man-made surface in the rock formation. The invention also relates to devices which are adapted for use in such methods .
Background
In nature, minerals of economic value are often found in ores such as sulphide ores (for example copper, lead and zinc) , oxide ores (for example aluminum, chromium, vanadium, iron, titanium or manganese) or metallic alloy ores (for example silver, gold, platinum group metals) . These ores are found in different concentrations ranging from semi-massive or massive bodies to very dispersed mineralisations. For many years people have mined rock formations with the aim of removing one or more ores, from which one or more minerals can be extracted during removal of the gangue.
In a mining or exploration operation, it is important to determine whether or not it is possible to make a profitable extraction from a particular rock formation. This will depend on several factors including the size and distribution of the ore within the rock formation and the concentration (grade) of the mineral within the rock formation. To determine the grade, it is known to carry out chemical analysis of a sample of the rock. Samples may be taken from the surface of the rock formation. Alternatively, to determine composition of the rock below the surface, an opening in the rock may be made by drilling, sawing, ploughing, blasting, hammering or by fracture caused by explosions or tension.
Traditionally, chemical analysis involves removing a sample of the rock from various points in a surface and analysing them remotely. This involves a time delay of several hours and up to a number of days between taking the sample and receiving the results of the analysis. In addition, the physical removal of samples from a surface is costly and the samples must be labelled very carefully to ensure that the people involved in the operation know which part of the surface each sample came from. Often, inaccuracies arise in relation to the exact original location of samples.
In rock formations the concentrations of minerals are often heterogeneous. That is, the concentration of mineral varies significantly in different regions of the formation. The mineral may be found in very high or very low concentrations and may even be absent from some regions. Furthermore, minerals often comprise grains or crystallites or crystals with varying chemical compositions and the average chemical composition of the ore varies with position in the mineralisation.
One major difficulty with the traditional method is accurately determining the location of the ore without taking a prohibitively high number of samples. The miner is faced with a choice.
One option is to take samples from positions within the removed material that are very close together, which can lead to an accurate determination of the composition of the surface but is very lengthy and costly. It is also inefficient because the ore could be completely absent from a large proportion of the sampled surface.
The alternative is to take infrequent measurements which would result in less costly analysis. However, because of the often heterogeneous nature of a rock formation, is likely to give inaccurate results and subsequently lead to inefficient mining.
Other analytical methods that have previously been used in exploration and mining are X-ray fluorescence (XRF) , AAS, ICP and neutron activation. However, none of these methods can provide reliable quantitative in-situ analysis because of the need for sample preparation. Relatively long return times also limit the use of these analytical methods. Furthermore, the apparatus used in methods involving XRF is large and can not be used in typical holes .
The invention aims to provide a method of chemical analysis which is adapted for use in analysis of chemically heterogeneous rock formations and which can be used in-situ to determine efficiently and in real time the location, distribution and concentration of a mineral in a rock formation.
It als.o aims to provide an apparatus and a device adapted for use in such methods . Summary of Invention
The invention provides, in a first aspect, a method of spatial analysis of a chemically heterogeneous rock formation, comprising determining a chemical analysis of a man-made surface of the rock formation, the method comprising the steps of : providing the man-made surface; providing a device which is adapted to emit a beam of laser light so as to generate a plasma at a first point on the surface, and a light collector; taking a first measurement by generating a plasma at the first point, collecting light from the plasma with the light collector, transmitting it to a spectrophotometer and determining a chemical analysis of the surface at the first point.
A second aspect of the invention provides an apparatus for use in carrying out spatial analysis of a chemically heterogeneous rock formation, the apparatus comprising: (a) a laser which is adapted to generate a beam of laser light;
(b) a device adapted to emit a beam of laser light and comprising (i) a focus means adapted to focus the laser light before emission so that a plasma is generated at a surface adjacent the device, (ii) a light collector positioned so as to collect light from the plasma, (iii) an outer housing containing the focus means and the light collector,
(c) a spectrophotometer (d) light guidance means adapted to guide light from the laser to the focus means
(e) light guidance means adapted to guide light from the light collector to the spectrophotometer and
(f) a movement controller adapted to move the point at which the plasma is emitted relative to the surface.
The device which is the part of the apparatus which emits the laser light is a third aspect of the invention.
The invention uses laser induced plasma spectroscopy (LIPS) to carry out chemical analysis. By so doing, the invention has many advantages, especially in a mining or exploration operation. For instance, no sample removal from the rock formation is required and thus minimal or no sample preparation is needed and there are no special requirements as to the state of the sample surface (in particular porosity, whether the surface is wet or dry) . In some cases it may be advantageous to remove dust or mud from the surface before taking measurements but no other special preparation is required. In addition, there is no need for provision of a special atmosphere such as inert gas, a vacuum or dry air. The ability to analyse without removing samples from the surface greatly increases the accuracy of determining the distribution of the ore mineral within the formation and further facilitates spatial analysis
(ie determination of aspects of low chemical composition varies across the rock analysed) .
Furthermore, LIPS can give real-time analysis meaning that the time between operating the laser and analysing the composition of the rock surface is less than 60 minutes, usually less than 30 minutes and can be below 15 minutes or 5 minutes but is most preferably between 30 seconds and 1 minute.
The device, apparatus and methods of analysis of the invention are advantageous in the mining industry as they are particularly adapted for use in relatively narrow openings having high length to diameter ratio
(eg above 10 or even above 20) . In particular the invention allows determination of the chemical analysis of the inner surfaces of drilled holes in rock formations.
LIPS has been used in the past with respect to analysis of soil (which is rather soft in comparison with rock formations, and in which mobility of elements is generally greater than in rocks) , in particular to determine the level of contamination of soil (see US Department of Defence Environmental Security Technology Certification Program published April 2003) .
A further example of use of LIPS is disclosed in Yamamoto et al . , Applied Spectroscopy, 50(2) , 222-33 (1996) which describes a portable LIPS instrument for analysis of metals in soil and lead in paint using a nanosecond pulsed laser which fits into a small suitcase .
We believe that LIPS may also have been used for exploration methods but only for rather homogeneous rock faces and not in such a manner as to generate a spatial analysis .
However, the prior art does not address the particular problems which arise with analysing a chemically heterogeneous rock formation or the requirements for analysing an inner surface of a hole in a rock formation.
In the invention we analyse rock formations, which have hard surfaces . The rock is generally consolidated sedimentary rock or igneous rock.
The man-made surface can be made by grinding, drilling, sawing, ploughing, blasting, hammering or by fracturing caused by man-made explosions or tensions . The invention is particularly useful for analysis of openings with relatively high ratio of length to diameter, as it is particularly difficult to analyse these accurately and efficiently using conventional methods. Examples of such openings are: holes used for pre- extraction exploration and prospecting of metals or minerals, where the depth is usually 0.1 to 1000 meters but can be up to 1500m and the diameter is 1 to 70 cm at the narrowest point; holes used for blasting in the mining industry, where the depth of the hole is usually 0.1 to 50 meters and the diameter at the narrowest point is 1 to 20 cm,- and channels made by sawing or grinding the surface of a rock formation used for pre-extraction exploration and prospecting of metals or minerals, where the depth of the channel is usually 1 to 100 centimetres and the width at the narrowest point is 0.1 to 10 centimetres.
The depth of the opening is preferably between 0.1 - and 1000m and the width of the opening at the narrowest point is preferably between 1 and 100cm, more preferably 1.5 and 50cm, most preferably 1.5 and 16cm.
Preferably the opening in the rock formation has a diameter which is not more than 200% of the diameter of the device.
The invention makes use of the known laser induced plasma spectroscopy (LIPS) technique for chemical analysis.
By chemical analysis we mean the obtaining of information about the presence (qualitative) or amount, absolute or relative (quantitative) ,of one or more chemical elements. For instance, the presence of a single element can be detected, or the ratio (s) between two (or more) elements, or the amount of one or more elements .
The LIPS technique uses a pulsed laser to generate a laser spark which rapidly heats a sample causing vaporization, dissociation into atomic species, and ionisation, which produces a plasma. As the plasma cools, the excited species relax and emit optical energy at characteristic wavelengths. The emission can be spectrally resolved to identify the elemental species that are present in the sample based on the presence of characteristic spectral lines. The concentration of the elemental species present may be proportional to the intensity of the spectral lines produced or, if it is not proportional, may be calculated by descent calibration. The invention does not require any specific type of LIPS, meaning that any suitable type of laser, duration of laser pulse, type of detector or spectrophotometer to resolve the emitted energy, etc. can be used. The plasma can be generated using repetitive single spark laser pulses or repetitive double spark laser pulses. Examples of such pulsed lasers are Nd:YAG and Excimer lasers. Typically a Nd:YAG laser is used with 532 or 1054nm wavelength. Laser pulse duration can range from femtosecond laser pulses to 50 nanoseconds. Pulse energy can be from 5 mJ upward, for instance up to around 25OmJ and is preferably 20 to 50 mJ. Pulse frequency can be from 1 Hz but is typically from 5 Hz upwards, for instance up to about 50 Hz and is preferably between 10 and 50 Hz, most preferably about 20 Hz. LIPS can be used both as a quantitative and qualitative analytical method for chemical analysis. Entire spectra can be analysed in order to make a quantitative chemical analysis. Alternatively only a narrow part of the spectrum can be analysed in order to gain qualitative information about the presence of a single component, a selection of components, ratio between components or combinations thereof.
The analysis involves taking a measurement by generating a plasma at a point, collecting light from the plasma with the light collector, transmitting it to a spectrophotometer and determining a chemical analysis of the rock at the point on the surface.
The laser beam is generated by a laser. The beam of laser light is emitted from the device which is adjacent the surface. The laser may form part of the device. Alternatively, it may be positioned away from the rock surface being analysed and connected to the device by light guidance means which transmit the laser light to the device. Examples include optical fibres. Generally, and in the second aspect of the invention essentially, the device comprises a focus means which focuses the laser light. The focused light .is emitted from the device and generates a plasma at the surface. The focus point of the laser beam may be at or slightly behind the surface.
The invention requires collecting the light generated by relaxation of the species in the plasma. Generally the light collector is a lens and the collected light is transmitted to the spectrophotometer by light guidance means, such as optical fibres.
The LIPS technique uses a spectrophotometer as a means of analysing the light from the plasma. The spectrophotometer can be any suitable type. Preferably an Echelle spectrograph is used.
Generally the spectrophotometer is located away from the surface to be analysed. The invention generally also uses a detector such as a CCD or ICCD (intensified CCD) . The data from the spectrophotometer should be translated into a chemical analysis by using suitable software provided, for example provided in a PC. The spectrophotometer may have an input into a user- interface or a feedback system. The detector is positioned between the spectrophotometer and the analysis software. The detector transmits the data from the spectrophotometer to the software and can store information from the spectrophotometer.
The invention provides spatial analysis of the chemical content of the rock formation. That is, it provides a determination of the variation of the chemical analysis over a region of the rock formation. To achieve this, the method requires that measurements are taken at at least two different points on the man- made surface, and preferably at least 10, more preferably at least 100 points and usually even more.
The apparatus used in the invention includes a movement control system which moves the point at which the plasma is generated relative to the rock surface. The chemical analysis of the surface can be made along the length direction of openings such as holes, cores or tracks in order to describe features of the chemical composition and variations thereof. Alternatively a number of spots within an area, around the perimeter of an opening or at the edge of a track can be analysed in order to establish features of the chemical composition at a certain position.
The movement control system is used to move the device to enable measurements to be taken at different points on the surface.
There are at least two different and complementary mechanisms by which the movement control system can operate. The device usually includes an outer housing so that the point at which the plasma is generated is adjacent to the outer housing. • •
In a first mechanism, the movement control system moves the outer housing relative to the rock surface. This is particularly useful when the device is carrying out a scanning operation (as discussed below) .
In a second mechanism, the movement control system moves the point at which the plasma is generated relative to the outer housing. This is a fine movement and can be used during a more detailed analysis of the surface. This allows the point at which the plasma is generated to be moved without moving the outer housing of the device itself.
The movement control system can be any suitable design, for instance using a spindle to achieve movement of the point at which the plasma is generated relative to the outer housing.
Generally the movement controller includes control software which can be operated by a user distant from the device and the surface to be analysed.
The device preferably comprises an outer housing which is preferably made of plastic, metal, ox any material which is rigid and strong enough to withstand any accidental knocks against the surface. Examples are stainless steel, Inconel ®, bronze and titanium. The outer housing usually has an opening or window through which the laser beam can be emitted from the device.
Within the outer housing is preferably an inner housing which is typically made of a plastic or metal material . The inner housing also usually has an opening or window in it through which the laser beam can pass.
If located within the device, the laser is generally located within the inner housing, preferably in a fixed position relative to the inner housing. Preferably the inner housing is moveable relative to the outer housing. This is typically achieved by use of the movement control system.
The outer housing and the inner housing can each be pressurised in order to prevent dust from entering the device. Alternatively, the windows in the inner and outer housing can be covered in glass through which the laser'beam can pass, to prevent and debris evtering the housing. The glass is usually spherical. In addition, the device may contain an air nozzle or vent to blow away dust from the point to be analysed.
The device preferably includes a positioner which is adapted to maintain a predetermined distance between the outer housing and a rock surface. The positioner is preferably one or more spacers which are connected to the outer housing and which maintain a predetermined distance between the outer housing and the rock surface.
The device preferably includes at least two spacers. Preferably also the device has a longitudinal axis and longitudinal sides substantially parallel to the longitudinal axis. Preferably there is at least one spacer on a first longitudinal side of the device and at least one spacer on a second, opposite, longitudinal side of the device. At least one spacer can be resiliently biased so as to create a force holding the device against the inner surface of an opening in a rock formation.
Where the man-made surface is a drilled hole then the hole can be of a size predetermined to be of diameter slightly greater than that of the device, so that there is no need for spacers.
The spacers can be made of any suitable material which is capable of withstanding handling and possible impact on a rock surface.
When the device is in use, it preferably moves across the rock surface in a direction parallel to its longitudinal axis. Preferably the point at which the plasma is generated also moves in a direction parallel to the longitudinal axis of the device. Alternatively or in addition, the point at which the plasma is generated can be moved so that it rotates about the longitudinal axis of the device. This latter option is particularly useful when the surface is a drilled hole. Preferably the rock surface comprises sulphide minerals, oxide minerals or metallic alloys. The method of the invention is particularly useful when the mineral and/or the ore is invisible with the naked eye. This is often the case for precious metals such as gold and platinum group elements. The need for chemical analysis and in particular accurately and efficiently targeted chemical analysis increases if the mineral and/or ore is not visible to the naked eye.
The invention is also particularly useful when the concentration of the mineral in the rock is low. The invention is particularly useful when the mineral forms less than 50% of the composition of the rock, preferably less than 20%, more preferably less than 10% and most preferably less than 1%. The invention is suitable for use in mining in a rock formation in which there is a heterogeneous (non- continuous) distribution of elements to be analysed. The invention is particularly useful for mining and exploration activities related to platinum group metals, gold, silver, zinc, copper, vanadium, nickel, chromium, cobalt, titanium, lead, niobium, molybdenum, tantalum, tungsten, tin, antimony, bismuth and rare earth elements (and combinations thereof) . The invention is particularly useful for precious metals, for example platinum group metals, gold and silver, because these precious metals are very high in value. The invention is also useful in diamond mining or exploration as diamonds are known to be associated with certain mineral compositions. The most common mineral compositions indicating a higher possibility of the presence of diamonds are, olivine (Fe/Mg) where the iron to magnesium ratio is important, ilmenite (Fe/Ti) the iron to titanium ratio is important and garnet (Cr, Mg, Ca, Fe) where the content and ratios are also important.
The invention is useful in exploration methods These include searching for deposits of useful minerals and in establishing the nature of a known mineral deposit, preparatory to development. It may also be used during mining operations, that is processes of extracting mineral deposits from rock formations.
The invention can also be useful in oil exploration and drilling.
The invention also provides preferred processes which are particularly efficient. The size of a spot analysed using LIPS can have a volume of approximately 1 μm3 but may have a much larger volume, of between 0.05 and 0.2 mm , preferably around 0.1mm . This is typically smaller than a grain or crystallite in a mineral. However, as the chemical composition can vary between grains or crystallites, an average must be taken from a number of measurements to get an accurate result . Typically the average should be taken from a large number of measurements (over 100) from a small area (of about 100 cm2) to give a very accurate reading. Over a large surface, this can be very slow.
The heterogeneous distribution of rock formations generally means that the distance between grains, inclusions and/or crystallites is typically between 10 and 10000 times higher than the size of the plasma generated by LIPS. The apparatus and the method of the invention allow for inclusion of a feedback system. This can be used in conjunction with the movement controller to determine the movement of the device over the surface . Measurements can then be taken at points along the surface. The feedback system also allows for analysis to be done in stages of increasing accuracy so that detailed analysis of the entire surface is not necessarily carried out . A scanning stage can be used to identify areas likely to contain the ore and then subsequent stages concentrate the analysis to determine the concentration of the ore and mineral in these areas. Hence, the efficiency can be greatly improved.
The apparatus and device of the invention preferably comprise a feedback system which is adapted to control the movement controller- in accordance with input from the spectrophotometer. The input is produced using the information obtained from the spectrophotometer when its signal has been processed. The feedback system of the invention ensures efficiency and quality of the chemical analysis . The feedback system can determine the speed of the device relative to the surface of the sample, the number of points to be analysed, the position of the points and the number of measurements to be taken at each point.
The aim of this system is to identify areas where the ore is present by making a highly reduced number of measurements as compared to a detailed analysis of the chemical compositions with high spatial resolution along the length of the surface.
The feedback system can also make use of conventional statistical methods for geological exploration and sampling such as semi-variogram and Kriging or the use of an optical system for visual inspection of the sample surface or the use of a reduced number of measurements combined with conventional statistical methods or the use of knowledge obtained from pre-exploration studies and geology in general or combinations thereof. A preferred method involves the device being used to analyse features of the composition of the surface in a number of stages.
In a preferred embodiment, the method additionally uses a feedback system which controls the movement of the device in accordance with input from the information obtained from the spectrophotometer and wherein the method additionally comprises the steps of; scanning by moving the point at which the plasma is generated over the surface and taking measurements at predetermined scan points; using the feedback system to compare the chemical analysis at the scan points with predetermined criteria, selecting a number of sample areas on the surface where the chemical meets predetermined criteria, and within each- sample area; moving the point at which the plasma is generated over the surface within the sample area, and taking measurements at predetermined fine measurement points. Hence, the first step is typically scanning. This involves moving the device over a macroscopic area and taking measurements at scan points to identify the types of minerals that are present in the rock. The scan points are preferably between 0.1 and 1 m from each other.
From this scanning stage, main mineral phases of the rock can be identified, for example whether the rock comprises carbonate, quartz, feldspar, amphibole etc.
The results are then compared by the feedback system with predetermined criteria, for example, if the mineral is associated with a sulphide phase the feedback system will ""choose ' ' sample areas which comprise a sulphide phase to undergo subsequent more detailed analysis.
At the scan points the aim is to determine the general type of the rock rather than accurate levels of particular elements. Therefore, the detection limit does not need to be particularly ' high compared to later analytical stages and a smaller number of measurements
(typically less than 100, preferably less than 10) need to be made at each scan point. This means a large surface can be scanned in a relatively short time.
The sample area chosen varies according to the nature of the mineralization. However, a typical width is between 0.01 and 1 m. The sample area is significantly larger than the typical size of grains or crystals .
The next stage typically is a more detailed analysis or fine measurement within each sample area. Within the sample area, a number of measurements on a microscopic scale are carried out at fine measurement points on the surface. This means that the fine measurement points are between 0.5 and 1000 μm from each other, preferably between 1 and 50 μm from each other. The fine measurement points should be spaced throughout the sample area to ensure that the measurements are made on a large number of different crystals. This enables an accurate result to be obtained.
The feedback system works by taking an average of a number of measurements at the fine measurement points to get an accurate determination of the overall chemical analysis within each sample area. Preferably there are at least between 1 and 20 fine measurement points within each sample area, but there can be at least 50, at least 100, or even at least 150.
To improve the detection limit of the device typically many measurements or spectra are taken at each fine measurement point. This allows taking into account the background noise in the spectra and to ensure that the spectrophotometer can pick up a low level of the mineral. The detection limit should be below lOOppm, preferably below 50ppm. To achieve this, typically more than 100, preferably more then 200, most preferably more than 300 measurements are taken at each fine measurement point .
In the present invention, other analytic techniques can be used in combination with LIPS, for example an optical system for ' visual inspection of the sample surface. Other suitable techniques include geophysical methods such as magnetic field measurements (eg Fluxgate magnetometer) , inclination sensor (accelerometer) , electrical resistance measurements, acoustic methods and radiation detection devices.
Brief Description of the Drawings
Figure 1 shows a cross section through a device according to a preferred embodiment of the present invention. Figure 2 shows a device according to a preferred embodiment of the present invention. Detailed Description of the Drawings
The Figures both show a device (21) within a man- made hole drilled in a rock formation (20) . The device is adjacent to the inner surface (1) of the hole.
The device has outer housing (2) with spacers (4) attached to it . The spacers are located above and below the opening (3) in the outer housing (2) through which the laser beam is emitted. The spacers (4) maintain a predetermined distance between the outer housing (2) and the rock surface (1) .
The spacers (4) on the opposite side of the housing have a bias mechanism (5) . This ensures that the spacers on the opposite side of the housing from the opening (3) are in contact with the surface of the hole. The device comprises an inner housing (6) in which the laser (8) is located. The inner housing can be moved with respect to the outer housing by means of one aspect of the movement controller (7) . The device comprises an optical system (11) and a lens (10) which directs the laser beam through an opening . (12) in the inner housing (6) and the opening (3) in the outer housing (2) . In an alternative embodiment windows rather than openings are present in both the inner and the outer housing through which the laser beam can pass. The laser beam is directed at the rock surface (1) and the optical system (11) , lens (10) , laser (8) and outer housing (2) are positioned so that the focus point of the laser beam is at or behind the surface. The device also comprises a light collector (9) which, in this case, is an optical fibre and is positioned so that it can collect light from the plasma generated by the laser at the surface. The device includes a sealing means (14) which prevents dust from entering the space between the inner and outer housing.
The device includes a power cord (15) which supplies power to the parts of the device that need it such as the laser (8) and the fine movement controller (7) .
A cable (17) is shown in Figure 1 which is part of a movement controller and moves the device relative to the rock surface.
Signal wire (16) is a part of the feedback system and relays information about the location of the device relative to the surface and the location of the point at which the plasma is generated.
As shown in Figure 2, the spectrophotometer (23) is located, in this embodiment, on the ground outside the hole.
In the embodiment in Figure 2, the movement controller (24) is located above the hole and a user interface (22) is located above the hole and the feedback system can be controlled from here. The movement controller can also be controlled from the user interface and the results of the chemical analysis from the spectrophotometer can be reviewed via the user interface. Examples Example 1 The method of the invention is used in the investigation of a mineralisation of platinum in chromite present in pyroxenite. The platinum is known to be located in a sulphide phase in the chromite .
The sulphide content in the chromite is known to be between 0 and 5% and the sulphide phase typically contains 0 to 100 ppm platinum.
A minimum average concentration of 1 ppm platinum is required for a profitable mining operation in this location. The presence of chromium, magnesium, aluminium and silicon indicate a pyroxenite mineral. A hole which is 500 meters long is made in the rock formation by grinding.
The information relating to the hole, the mineral and ore and feasible concentrations is fed into the feedback system via the user-interface. The inner surface of this hole is analysed by a method of the invention. The surface is divided into 1 meter segments along the length to give a total of 500 segments. A reasonably accurate determination of the concentration of chromium, magnesium, aluminium and silicon is achieved by taking 200 measurements per segment (i.e. having scan points every 0.5 cm) . One measurement per scan point is taken. A 10 Hz pulsed laser is used which takes 10 measurements per second and the device has a speed of 5 cm/s relative to the sample surface. The scanning operation has a duration of approx. 3 hours.
The result is the identification of 50 meters pyroxenite, which needs to be further characterised.
The next step is the positioning of a number of sample areas within the chromite-containing phase is such way that the results of the measurements in these positions results in a meaningful description of the phase. The feedback system will often position a number of sample areas equidistantly over the phase of interest. In this case 10 sample areas with a length of 10 cm and a width of 10 cm are positioned equidistantly over the 50 meters of the pyroxenite phase. The size of the sample area is significant larger than the size of the grains or crystals on the surface to ensure that the fine measurement points within the sample area hit a high number of different grains or crystals (a high number of fine measurement points on the same grain or crystal would not result in the average chemical analysis within that sample area) .
The number of fine measurement points that should be analysed within each sample area depends on the required accuracy. In this case 150 fine measurement points are analysed within each sample area and the fine measurement points are positioned equidistantly within the sample area.
200 plasma are created at each fine point to give a detection limit below 50 ppm. The detector creates a spectra from the 200 measurements which has. a very high level of accuracy.
The average chemical composition within the sample area is calculated from the results from the 150 fine measurement points analysed.
The results from one sample area are 1 fine measurement point with 80 ppm platinum, 1 fine measurement point with 60 ppm platinum, 1 fine measurement point with 50 ppm platinum, 1 fine measurement point with 40 ppm platinum, and 146 fine measurement points with no platinum (or a platinum content below the detection limit) .
The average platinum content is then calculated as (80+60+50+40) /150 ppm = 1.53 ppm platinum within this sample area.
The duration of this step is approx. 7 hours, meaning that the 500 meters long surface is characterised within a day. Example 2 In this example a method of the invention is used to investigate the spatial concentration of platinum from example 1. This example additionally involves use of an optical feedback system.
Once the pyroxenite has been identified (scanning step) , then the presence and position of the sulphide within the pyroxenite is investigated using an optical system. Such a system consists of a source of light with a wavelength that is mainly reflected by the sulphide phase and not by the pyroxenite. This reflection is used to direct the device to the sulphide phase and is a very efficient way to clarify whether the sulphide phase is present and if it contains any platinum.
Once it is established that the sulphide phase contains sufficient amounts of platinum to be of interest, the feedback system selects a high number of fine measurement points to be analysed in order to determine the average content of platinum and sulphide. Example 3 In this example a method according to the invention including a feedback system is used in the investigation of the spatial concentration of gold in a blasting hole in a mining operation.
A minimum concentration of 2 ppm gold is required for a profitable mining operation in this location. The aim of the investigation is to ensure that only rocks with a gold content of minimum 2 ppm are released at the blasting.
The blasting hole in this example is 3 meters deep and it is thought to be possible that the gold content drops below 2 ppm at a certain depth within the hole. This information is entered into the feedback system. No information about the distribution or grain size is- available. In this case it is important to minimise the standard deviation of the calculated gold content . A sufficiently high number of fine measurement points need to be analysed within each sample area. Only 20 spectra are taken at each fine measurement point, as gold is most often located in grains with a fairly high gold content. The number of fine measurement points is chosen to be 1000 and the size of the sample area is 4 cm by 10 cm (width by length) . The analysis of each sample area takes approx. 35 minutes when the 10 Hz pulsed laser is used. After the first sample area is analysed the feedback system is used to evaluate whether 1000 fine scan points within a sample area results in a sufficiently accurate determination of the gold content within that area. During the analysis of the blasting hole, the first sample area is positioned at the bottom of the hole (i.e. at a depth of 3 meters) . If the result showed a gold content above 2 ppm no further analysis is needed and the explosives can be positioned at the bottom of the blasting hole. If the gold content is found to be 1.0 ppm at the bottom of the hole, the next sample area is positioned 1 meter from the bottom (i.e. at a depth of 2 meters) .
If the gold content is 1.8 ppm, in this case one can assume a linear variation in the gold content and use linear extrapolation and estimate that the gold content should be above 2 ppm at a depth of 1.75 meters
(had the result showed a gold content of 2.5 ppm then the estimated depth would have been 2.33 meters) . The bottom 1.25 meters of the blasting hole could then be closed (e.g. by a solid stick made from wood) and the explosives positioned at a depth of 1.75 meters.
Alternatively the sample area is positioned at a depth of 1.75 meters in order to verify that the gold content is above 2 ppm. In order to decide whether or not the verification measurement is needed, the results are compared with other nearby blasting holes in order to evaluate whether the results seem reasonable. If one blasting hole showing a gold content of 2 ppm at a depth of 3 meters is surrounded by blasting holes showing no gold at a depth of 3 meters, then the result showing 2 ppm is likely a faulty measurement, and is repeated. Example 4
This example relates to the investigation of the concentration of platinum in an exploration hole in relation to an ""invisible ore1' type of mineralisation. This means that the ore is not visible to the naked eye.
In this particular mineralisation, the platinum content is related to the ratio between cobalt and nickel. A scanning stage has been carried out and it is known that the cobalt and- nickel are uniformly distributed within the sample and the concentration is 0 to 100 ppm. An atomic cobalt/nickel-ratio > 2.5 indicates a platinum content above 1 ppm. In this case the sample areas are positioned at 1 meter intervals. Each sample area is analysed at 20 fine measurement points and 200 spectra are taken at each fine measurement point to have a sufficiently low detection limit for cobalt and nickel. Using 10 Hz laser pulses (i.e. 10 spectra measured per second) , the time for analysing each sample area is
400 seconds. Further chemical analyses are carried out once areas with a potential platinum content above 1 ppm have been identified.

Claims

1. A method of spatial analysis of a chemically heterogeneous rock formation, comprising determining a chemical analysis of a man-made surface of the rock formation, the method comprising the steps of: providing the man-made surface; providing a device which is adapted to emit a beam of laser light so as to generate a plasma at a first point on the surface, and a light collector; taking a first measurement by generating a plasma at the first point, collecting light from the plasma with the light collector, transmitting it to a spectrophotometer and determining a chemical analysis of the surface at the first point, and taking at least one further measurement at a further point on the surface.
2. A method according to claim 1 which is carried out during a mining operation.
3. A method according to claim 1 which is carried out during an exploration operation.
4. A method according to any preceding claim wherein the device includes an outer housing and a laser within or the outer housing so that the point at which the plasma is generated is adjacent to the outer housing.
5. A method according to any of claims 1 to 3 wherein the device is connected to a laser which does not form part of the device and the device includes an outer housing and a focusing element the outer housing so that the point at which the plasma is generated is adjacent to the outer housing.
6. A method according to claim 4 or claim 5 comprising taking at least one further measurement at a further point on the surface by moving the point at which the plasma is generated relative to the outer housing.
7. A method according to claim 4 or claim 5 comprising taking at least one further measurement at a further point on the surface by moving the outer housing relative to the surface.
8. A method according to any preceding claim additionally comprising operating a feedback system wherein the method additionally comprises the steps of; scanning by moving the point at which the plasma is generated over the surface and taking measurements at predetermined scan points; comparing the chemical analysis of the surface at the scan points with predetermined criteria, selecting a number of sample areas on the surface where the chemical analysis meets predetermined criteria, and within each sample area; moving the point at which the plasma is generated over the surface within the sample . area, and taking measurements at predetermined fine measurement points.
9. A method according to claim 8 wherein the scan points are between 0.1 and 10 m from each other, the width of the sample area is between 0.1 and 1 m and the fine measurement points are between 10 and 1000 mm from each other.
10. A method according to claim 8 or claim 9 wherein there are at least 50, preferably at least 100, more preferably at least 150 fine measurement points within each sample area.
11. A method according to any preceding claim wherein at least 100 measurements are taken at each fine measurement point, preferably at least 200, more preferably at least 300.
12. A method according to any preceding claim wherein the time between operating the laser at the first point and determining the chemical analysis of the surface at that point is less than 30 minutes, preferably less than 15 minutes, more preferably less than 5 minutes.
13. A method according to any preceding claim which is a method of mining for an ore mineral which is invisible to the naked eye.
14. A method according to claim 13 wherein the ore mineral forms less than 50% of the composition of the rock formation, preferably less than 20%, more preferably less than 10% and most preferably less than 1%.
15. A method according to any preceding claim wherein the rock formation contains metallic ore mineral, preferably selected from the. group consisting of platinum' group metals, silver, gold, zinc, copper, vanadium, nickel, chromium, cobalt, titanium, lead, niobium, molybdenum, tantalum, tungsten, tin, antimony, bismuth and rare earth elements.
16. A method according to any preceding claim wherein the spectrophotometer is located away from the man-made surface.
17. A method according to any preceding claim wherein the laser light is generated by a laser located away from the man-made surface.
18. A method according to any preceding claim wherein the device has a longitudinal axis and during the method the device moves across the surface in a direction parallel to the longitudinal axis.
19. A method according to any preceding claim wherein the device has a longitudinal axis and the point at which the plasma is generated moves in a direction parallel to the longitudinal axis of the device.
20. A method according to any preceding claim wherein the man-made surface is the inner surface of an opening having a ratio of length to diameter of at least 10, preferably at least 20.
21. A method according to claim 20 wherein the opening has a diameter which is not more than 200% of the diameter of the device, preferably not more than 150% of the diameter of the device.
22. A method according to claim 20 wherein the diameter of the width of the opening at its narrowest part is between 10 and 1000 mm, preferably 15 to 500 mm, more preferably 15 to 160 mm.
23. A method according to claim 20 wherein the opening is a drilled hole in a rock formation.
24. A method according to any preceding claim wherein the device includes an outer housing and the outer housing does not come into contact with the surface .
25. A method according to any preceding claim wherein the device includes an outer housing and connected to the outer housing are spacers which maintain a predetermined distance of the outer housing from the surface .
26. A method according to claim 20 wherein the device includes an outer housing and at least two spacers and wherein the device has a longitudinal axis and longitudinal sides substantially parallel to the longitudinal axis and there is at least one first spacer on a first longitudinal side of the device and at least one spacer on a second longitudinal side substantially opposite the at least one first spacer, and at least one spacer is resiliently biased so as to create a force holding the device against the inner surface of the opening.
27. A method according to any preceding claim wherein the surface is treated prior to generating the plasma, preferably wherein the treatment includes removing dust or mud.
28. An apparatus for use in carrying out spatial analysis of a chemically heterogeneous rock formation, the apparatus comprising:
(a) a laser which is adapted to generate a beam of laser 1ight; (g) a device adapted to emit a beam of laser light and comprising (i) a focus means adapted to focus the laser light before emission so that a plasma is generated at a surface adjacent the device, (ii) a light collector positioned so as to collect light from the plasma, (iii) an outer housing containing the focus means and the light collector,
(h) a spectrophotometer
(i) light guidance means adapted to guide light from the laser to the focus means (j) light guidance means adapted to guide light from the light collector to the spectrophotometer and
(f) a movement controller adapted to move the point at which the plasma is emitted relative to the surface.
29. An apparatus according to claim 28, wherein the movement controller is adapted to move the point at which the plasma is emitted relative to the outer housing.
30. An apparatus according to claim 28, wherein the movement controller is adapted to move the outer housing relative to the surface.
31. An apparatus according to any of claims 28 to 30 additionally comprising (g) an inner housing within the outer housing.
32. An apparatus according to claim 31 wherein the inner housing is moveable relative to the outer housing.
33. An apparatus according to any of claims 28 to 32 in which the device comprises (h) a positioner which comprises at least two spacers, at least one of which is resiliently biased so as to create a force against a surface adjacent the device.
PCT/EP2005/007931 2004-07-23 2005-07-21 Analysis of rock formations by means of laser induced plasma spectroscopy WO2006008155A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
AU2005263614A AU2005263614B9 (en) 2004-07-23 2005-07-21 Analysis of rock formations by means of laser induced plasma spectroscopy
CA002574867A CA2574867A1 (en) 2004-07-23 2005-07-21 Analysis of rock formations by means of laser induced plasma spectroscopy
EP05788676A EP1779095A1 (en) 2004-07-23 2005-07-21 Analysis of rock formations by means of laser induced plasma spectroscopy

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0416512.2 2004-07-23
GB0416512A GB0416512D0 (en) 2004-07-23 2004-07-23 Analysis of rock formations

Publications (1)

Publication Number Publication Date
WO2006008155A1 true WO2006008155A1 (en) 2006-01-26

Family

ID=32922720

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2005/007931 WO2006008155A1 (en) 2004-07-23 2005-07-21 Analysis of rock formations by means of laser induced plasma spectroscopy

Country Status (6)

Country Link
EP (1) EP1779095A1 (en)
AU (1) AU2005263614B9 (en)
CA (1) CA2574867A1 (en)
GB (1) GB0416512D0 (en)
WO (1) WO2006008155A1 (en)
ZA (1) ZA200701442B (en)

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7490664B2 (en) 2004-11-12 2009-02-17 Halliburton Energy Services, Inc. Drilling, perforating and formation analysis
WO2011120086A1 (en) * 2010-03-29 2011-10-06 Datatrace Dna Pty Limited A system for classification of materials using laser induced breakdown spectroscopy
US8424617B2 (en) 2008-08-20 2013-04-23 Foro Energy Inc. Methods and apparatus for delivering high power laser energy to a surface
US8464794B2 (en) 2009-06-29 2013-06-18 Halliburton Energy Services, Inc. Wellbore laser operations
US8571368B2 (en) 2010-07-21 2013-10-29 Foro Energy, Inc. Optical fiber configurations for transmission of laser energy over great distances
US8627901B1 (en) 2009-10-01 2014-01-14 Foro Energy, Inc. Laser bottom hole assembly
US8662160B2 (en) 2008-08-20 2014-03-04 Foro Energy Inc. Systems and conveyance structures for high power long distance laser transmission
US8684088B2 (en) 2011-02-24 2014-04-01 Foro Energy, Inc. Shear laser module and method of retrofitting and use
US8720584B2 (en) 2011-02-24 2014-05-13 Foro Energy, Inc. Laser assisted system for controlling deep water drilling emergency situations
US8783360B2 (en) 2011-02-24 2014-07-22 Foro Energy, Inc. Laser assisted riser disconnect and method of use
US8783361B2 (en) 2011-02-24 2014-07-22 Foro Energy, Inc. Laser assisted blowout preventer and methods of use
US9027668B2 (en) 2008-08-20 2015-05-12 Foro Energy, Inc. Control system for high power laser drilling workover and completion unit
US9074422B2 (en) 2011-02-24 2015-07-07 Foro Energy, Inc. Electric motor for laser-mechanical drilling
US9080425B2 (en) 2008-10-17 2015-07-14 Foro Energy, Inc. High power laser photo-conversion assemblies, apparatuses and methods of use
US9089928B2 (en) 2008-08-20 2015-07-28 Foro Energy, Inc. Laser systems and methods for the removal of structures
US9138786B2 (en) 2008-10-17 2015-09-22 Foro Energy, Inc. High power laser pipeline tool and methods of use
FR3022029A1 (en) * 2014-06-10 2015-12-11 Centre Nat Etd Spatiales DEVICE FOR SPECTROSCOPIC ANALYSIS OF DRILLING CARROTS
US9244235B2 (en) 2008-10-17 2016-01-26 Foro Energy, Inc. Systems and assemblies for transferring high power laser energy through a rotating junction
US9242309B2 (en) 2012-03-01 2016-01-26 Foro Energy Inc. Total internal reflection laser tools and methods
US9267330B2 (en) 2008-08-20 2016-02-23 Foro Energy, Inc. Long distance high power optical laser fiber break detection and continuity monitoring systems and methods
US9347271B2 (en) 2008-10-17 2016-05-24 Foro Energy, Inc. Optical fiber cable for transmission of high power laser energy over great distances
US9360631B2 (en) 2008-08-20 2016-06-07 Foro Energy, Inc. Optics assembly for high power laser tools
US9360643B2 (en) 2011-06-03 2016-06-07 Foro Energy, Inc. Rugged passively cooled high power laser fiber optic connectors and methods of use
US9562395B2 (en) 2008-08-20 2017-02-07 Foro Energy, Inc. High power laser-mechanical drilling bit and methods of use
US9664012B2 (en) 2008-08-20 2017-05-30 Foro Energy, Inc. High power laser decomissioning of multistring and damaged wells
US9669492B2 (en) 2008-08-20 2017-06-06 Foro Energy, Inc. High power laser offshore decommissioning tool, system and methods of use
US9719302B2 (en) 2008-08-20 2017-08-01 Foro Energy, Inc. High power laser perforating and laser fracturing tools and methods of use
US9845652B2 (en) 2011-02-24 2017-12-19 Foro Energy, Inc. Reduced mechanical energy well control systems and methods of use

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2702332A1 (en) * 1977-01-21 1978-07-27 Deutsche Forsch Luft Raumfahrt Crystallographic analyser for geological investigations - has laser optical system lowered into borehole to test reflection characteristics of rock under investigation
US5757484A (en) * 1995-03-09 1998-05-26 The United States Of America As Represented By The Secretary Of The Army Standoff laser induced-breakdown spectroscopy penetrometer system
US5798832A (en) * 1994-05-02 1998-08-25 Nis Ingenieurgesselschaft Mbh Process and device for determining element compositions and concentrations
US5847825A (en) * 1996-09-25 1998-12-08 Board Of Regents University Of Nebraska Lincoln Apparatus and method for detection and concentration measurement of trace metals using laser induced breakdown spectroscopy
US6008896A (en) * 1998-07-01 1999-12-28 National Research Council Of Canada Method and apparatus for spectroscopic analysis of heterogeneous materials
WO2000014516A1 (en) * 1998-09-04 2000-03-16 Generation Technology Research Pty. Ltd. Laser-induced ionisation spectroscopy, particularly for coal
US6147754A (en) * 1995-03-09 2000-11-14 The United States Of America As Represented By The Secretary Of The Navy Laser induced breakdown spectroscopy soil contamination probe

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2702332A1 (en) * 1977-01-21 1978-07-27 Deutsche Forsch Luft Raumfahrt Crystallographic analyser for geological investigations - has laser optical system lowered into borehole to test reflection characteristics of rock under investigation
US5798832A (en) * 1994-05-02 1998-08-25 Nis Ingenieurgesselschaft Mbh Process and device for determining element compositions and concentrations
US5757484A (en) * 1995-03-09 1998-05-26 The United States Of America As Represented By The Secretary Of The Army Standoff laser induced-breakdown spectroscopy penetrometer system
US6147754A (en) * 1995-03-09 2000-11-14 The United States Of America As Represented By The Secretary Of The Navy Laser induced breakdown spectroscopy soil contamination probe
US5847825A (en) * 1996-09-25 1998-12-08 Board Of Regents University Of Nebraska Lincoln Apparatus and method for detection and concentration measurement of trace metals using laser induced breakdown spectroscopy
US6008896A (en) * 1998-07-01 1999-12-28 National Research Council Of Canada Method and apparatus for spectroscopic analysis of heterogeneous materials
WO2000014516A1 (en) * 1998-09-04 2000-03-16 Generation Technology Research Pty. Ltd. Laser-induced ionisation spectroscopy, particularly for coal

Cited By (49)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7490664B2 (en) 2004-11-12 2009-02-17 Halliburton Energy Services, Inc. Drilling, perforating and formation analysis
US7938175B2 (en) 2004-11-12 2011-05-10 Halliburton Energy Services Inc. Drilling, perforating and formation analysis
US8936108B2 (en) 2008-08-20 2015-01-20 Foro Energy, Inc. High power laser downhole cutting tools and systems
US9284783B1 (en) 2008-08-20 2016-03-15 Foro Energy, Inc. High power laser energy distribution patterns, apparatus and methods for creating wells
US10036232B2 (en) 2008-08-20 2018-07-31 Foro Energy Systems and conveyance structures for high power long distance laser transmission
US8511401B2 (en) 2008-08-20 2013-08-20 Foro Energy, Inc. Method and apparatus for delivering high power laser energy over long distances
US9719302B2 (en) 2008-08-20 2017-08-01 Foro Energy, Inc. High power laser perforating and laser fracturing tools and methods of use
US9669492B2 (en) 2008-08-20 2017-06-06 Foro Energy, Inc. High power laser offshore decommissioning tool, system and methods of use
US8997894B2 (en) 2008-08-20 2015-04-07 Foro Energy, Inc. Method and apparatus for delivering high power laser energy over long distances
US9562395B2 (en) 2008-08-20 2017-02-07 Foro Energy, Inc. High power laser-mechanical drilling bit and methods of use
US9360631B2 (en) 2008-08-20 2016-06-07 Foro Energy, Inc. Optics assembly for high power laser tools
US8636085B2 (en) 2008-08-20 2014-01-28 Foro Energy, Inc. Methods and apparatus for removal and control of material in laser drilling of a borehole
US8662160B2 (en) 2008-08-20 2014-03-04 Foro Energy Inc. Systems and conveyance structures for high power long distance laser transmission
US8424617B2 (en) 2008-08-20 2013-04-23 Foro Energy Inc. Methods and apparatus for delivering high power laser energy to a surface
US9267330B2 (en) 2008-08-20 2016-02-23 Foro Energy, Inc. Long distance high power optical laser fiber break detection and continuity monitoring systems and methods
US8701794B2 (en) 2008-08-20 2014-04-22 Foro Energy, Inc. High power laser perforating tools and systems
US9027668B2 (en) 2008-08-20 2015-05-12 Foro Energy, Inc. Control system for high power laser drilling workover and completion unit
US8757292B2 (en) 2008-08-20 2014-06-24 Foro Energy, Inc. Methods for enhancing the efficiency of creating a borehole using high power laser systems
US9089928B2 (en) 2008-08-20 2015-07-28 Foro Energy, Inc. Laser systems and methods for the removal of structures
US9664012B2 (en) 2008-08-20 2017-05-30 Foro Energy, Inc. High power laser decomissioning of multistring and damaged wells
US8820434B2 (en) 2008-08-20 2014-09-02 Foro Energy, Inc. Apparatus for advancing a wellbore using high power laser energy
US8826973B2 (en) 2008-08-20 2014-09-09 Foro Energy, Inc. Method and system for advancement of a borehole using a high power laser
US8869914B2 (en) 2008-08-20 2014-10-28 Foro Energy, Inc. High power laser workover and completion tools and systems
US9244235B2 (en) 2008-10-17 2016-01-26 Foro Energy, Inc. Systems and assemblies for transferring high power laser energy through a rotating junction
US9080425B2 (en) 2008-10-17 2015-07-14 Foro Energy, Inc. High power laser photo-conversion assemblies, apparatuses and methods of use
US9138786B2 (en) 2008-10-17 2015-09-22 Foro Energy, Inc. High power laser pipeline tool and methods of use
US9347271B2 (en) 2008-10-17 2016-05-24 Foro Energy, Inc. Optical fiber cable for transmission of high power laser energy over great distances
US9327810B2 (en) 2008-10-17 2016-05-03 Foro Energy, Inc. High power laser ROV systems and methods for treating subsea structures
US8540026B2 (en) 2009-06-29 2013-09-24 Halliburton Energy Services, Inc. Wellbore laser operations
US8528643B2 (en) 2009-06-29 2013-09-10 Halliburton Energy Services, Inc. Wellbore laser operations
US8534357B2 (en) 2009-06-29 2013-09-17 Halliburton Energy Services, Inc. Wellbore laser operations
US8678087B2 (en) 2009-06-29 2014-03-25 Halliburton Energy Services, Inc. Wellbore laser operations
US8464794B2 (en) 2009-06-29 2013-06-18 Halliburton Energy Services, Inc. Wellbore laser operations
US8627901B1 (en) 2009-10-01 2014-01-14 Foro Energy, Inc. Laser bottom hole assembly
WO2011120086A1 (en) * 2010-03-29 2011-10-06 Datatrace Dna Pty Limited A system for classification of materials using laser induced breakdown spectroscopy
US8571368B2 (en) 2010-07-21 2013-10-29 Foro Energy, Inc. Optical fiber configurations for transmission of laser energy over great distances
US8879876B2 (en) 2010-07-21 2014-11-04 Foro Energy, Inc. Optical fiber configurations for transmission of laser energy over great distances
US8720584B2 (en) 2011-02-24 2014-05-13 Foro Energy, Inc. Laser assisted system for controlling deep water drilling emergency situations
US9291017B2 (en) 2011-02-24 2016-03-22 Foro Energy, Inc. Laser assisted system for controlling deep water drilling emergency situations
US9845652B2 (en) 2011-02-24 2017-12-19 Foro Energy, Inc. Reduced mechanical energy well control systems and methods of use
US9074422B2 (en) 2011-02-24 2015-07-07 Foro Energy, Inc. Electric motor for laser-mechanical drilling
US8783360B2 (en) 2011-02-24 2014-07-22 Foro Energy, Inc. Laser assisted riser disconnect and method of use
US8783361B2 (en) 2011-02-24 2014-07-22 Foro Energy, Inc. Laser assisted blowout preventer and methods of use
US9784037B2 (en) 2011-02-24 2017-10-10 Daryl L. Grubb Electric motor for laser-mechanical drilling
US8684088B2 (en) 2011-02-24 2014-04-01 Foro Energy, Inc. Shear laser module and method of retrofitting and use
US9360643B2 (en) 2011-06-03 2016-06-07 Foro Energy, Inc. Rugged passively cooled high power laser fiber optic connectors and methods of use
US9242309B2 (en) 2012-03-01 2016-01-26 Foro Energy Inc. Total internal reflection laser tools and methods
WO2015189286A1 (en) * 2014-06-10 2015-12-17 Centre National D'etudes Spatiales Spectroscopic analysis device for drilling cores
FR3022029A1 (en) * 2014-06-10 2015-12-11 Centre Nat Etd Spatiales DEVICE FOR SPECTROSCOPIC ANALYSIS OF DRILLING CARROTS

Also Published As

Publication number Publication date
CA2574867A1 (en) 2006-01-26
AU2005263614B9 (en) 2009-03-05
AU2005263614B2 (en) 2009-01-15
GB0416512D0 (en) 2004-08-25
ZA200701442B (en) 2009-03-25
EP1779095A1 (en) 2007-05-02
AU2005263614A1 (en) 2006-01-26

Similar Documents

Publication Publication Date Title
AU2005263614B9 (en) Analysis of rock formations by means of laser induced plasma spectroscopy
Harmon et al. Laser-Induced Breakdown Spectroscopy–A geochemical tool for the 21st century
Harmon et al. Applications of laser-induced breakdown spectroscopy for geochemical and environmental analysis: A comprehensive review
Craigie Principles of elemental chemostratigraphy
Harmon et al. LIBS analysis of geomaterials: Geochemical fingerprinting for the rapid analysis and discrimination of minerals
Harmon et al. Geochemical fingerprinting by handheld laser‐induced breakdown spectroscopy
US20130169961A1 (en) System for classification of materials using laser induced breakdown spectroscopy
EP1937937B1 (en) A method and apparatus for elemental analysis of a fluid downhole
De Giacomo et al. Laser induced breakdown spectroscopy on meteorites
McMillan et al. Geological applications of laser‐induced breakdown spectroscopy
Díaz Pace et al. Analysis of minerals and rocks by laser-induced breakdown spectroscopy
Gonçalves et al. Laser-induced breakdown spectroscopy applied to environmental systems and their potential contaminants. An overview of advances achieved in the last few years
Lemière et al. New developments in field-portable geochemical techniques and on-site technologies and their place in mineral exploration
Haavisto et al. Laser-induced breakdown spectroscopy for rapid elemental analysis of drillcore
Lemière et al. XRF and LIBS for Field Geology
Elhamdaoui et al. Measuring the concentration of gold in ore samples by laser-induced breakdown spectroscopy and comparison with the gravimetry/atomic absorption techniques
Galbács et al. A study of stalagmite samples from Baradla Cave (Hungary) by laser induced plasma spectrometry with automatic signal correction
Uvarova et al. Top-of-holes sensing techniques: developments within Deep Exploration Technologies Cooperative Research Centre
Senesi et al. Field-portable and handheld LIBS
AU2007209544B2 (en) Sub-surface analysis of particulate substrates
Balaram et al. Developments in analytical techniques for chemostratigraphy, chronostratigraphy, and geochemical fingerprinting studies: Current status and future trends
Veneranda et al. Portable XRF and LIBS combined with chemometrics: a novel method for the in-situ geochemical sourcing of obsidian artefacts
Rukhlov et al. Rapid identification of sand-size mineral grains using portable XRF: A new method for indicator mineral surveys
Lemiere et al. Introduction: New developments in field portable geochemical techniques and site technologies and their place in mineral exploration.
Lemiere et al. Status and new developments in field portable geochemical techniques and on-site technologies for mineral exploration

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KM KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NG NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SM SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): BW GH GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LT LU LV MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 2574867

Country of ref document: CA

Ref document number: 2005263614

Country of ref document: AU

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 2005263614

Country of ref document: AU

Date of ref document: 20050721

Kind code of ref document: A

WWE Wipo information: entry into national phase

Ref document number: 2005788676

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 2005263614

Country of ref document: AU

WWE Wipo information: entry into national phase

Ref document number: 200701442

Country of ref document: ZA

WWP Wipo information: published in national office

Ref document number: 2005788676

Country of ref document: EP