USRE17212E - Mokinley stockton - Google Patents

Description

Feb. 12, 1929.

M KINLEY STOCKTON PROCESS OF AND APPARATUS FOR TREATING MINERAI 2 Sheets-Sheet 1 Original Filed July 20, 1925 /'7c 17/11. EV 6706K 7'0/Y INVENTOR.

' ATTORNEY:

Feb. 12, 1929. M KlNLEY STOCKTON Re. 17,212

PROCESS OF ANfi APPARATUS .FOR TREATING MINERALS 2 Sheets-Sheet 2 Original Filed July 20, 1925 Mc/(mus Y 6700c TON INVENTOR.

ATTORNEY.

Reissued Feb. 12, 1929.

' UNITED STATES PATENT OFFICE.

MoKINLEY STOCKTON, OF LOMPOC, CALIFORNIA, ASSIGNOR TO THE CELIT DE COMPANY, 0] LOS ANGELES,'GALIFORNIA, A CORPORATION OF CALIFORNIA.

r-nocnssor ANDAAPPARATUS FOR TREATING lumnmns.

Original lq'o. 1,611,791, dated December 21, 1926, Serial No. 44,896, filed July 20, 1925. Application for reissue filed December 12, 1928'. Serial No. 325,611.

This invention pertains to the art of milling, disintegrating or crushing of mineral bodies to astate of fine division. a classification or separation of such milled mineral without the loss of the finest constituents, and also provides for the drying dehydration and calcination, or both, of such minerals.

The principal object of this'invention is to provide a method of milling a mineral, drying or calcining such milled mineral, and then separating the milled product into desired grades of fineness without the loss of the exceedingly fine particles produced by the milling operation. This method or process of operation may be effected in relatively simple, inexpensive apparatus, also disclosed and claimed by me. i

-Many mineralsand clays which it is desired to dry and mill, such'as, for example, diatomaceous earth, kieselguhr or infusorial earth, orsuch earths combined with'clay, contain high amounts of absorbed or combined water or both forms of moisture. In the case of diatomaceous earth, the raw or crude mineral contains as much as 65% absorbed moisture. It has. been found that most porous minerals in lump form, or minerals originally found with a high moisture content, resist a drying operation, after a portion of the Water has been removed, because of the fact that the outer surfaces of the material insulate the inner portions, and thereby prevent the rapid penetration of drying heat. It is, therefore, seen that if the drying operation is performed r on minerals in a finely divided form, the dry-.

ing heat may be applied to much greater benefit. The most effective drying operation, therefore, is that in which the mineral material is first ground to a suitable state of division and then exposed to or suspended in a heated medium or'gas so that each individual particle is surrounded by the heating or drying medium, The latter mode of operalion has been used on certain particular prod,

ucts by blowing the powdered or granular product into a receptacle or chamber, a heated gas being generally used. There has been dificulty experienced, however, in the subsequent separation of the powdered material from the gasp The dust problems arising from this 'method necessitating the use of electrical dust collectors, spraying systems and the like.

It is acknowledged that certain units of equipment similar to those comprising the apparatus herein disclosed have,been disclosed by the prio r'art, for example, conical air separating chambers have been used for such purpose, but to the bestof my knowledge, such units have never been connected, as shown by me, nor was it possible to heat, dry, separate, and mill or disintegrate a mineral in a closed circuit, and eliminate the loss which the dust is absorbed and retained. In

this manner a dust loss is not created and the use of expensive or elaborate dust collecting machinery is obviated, the form of apparatus which has been found to be adapted to the process being comparatively simple and inexpensive. My process is particularly adapted ations. encountered in the treatment of diatomaceous earth, kieselguhr or infusorial earth, or the like. It has been used with entire success in the production ofpowdered grades. of diatomaceous earth of such fineness that only 15% is left on a 150-mesh screen. while about 2040% of the material is less than 0.001 mm.- in size. Inasmuch as the dried, powdered diatoinaceous earth in this state of division weighs but 8 to 10 lbs. per cu. ft. great diificulty had hitherto been encountered 1n separating the dust of such product, from the gas or other fluid used in conveying or separating apparatus. 1

. The accompanying drawings give a diagrammatic illustration of my process and one 80 to the milling, drying, and separating opermodification thereof and at the same time fineness. Fig. 2 shows a modification of the process in which a mineral material is disintegrated, ,dried, calcined and separated into various grades of fineness. I

In Fig. 1 the raw or crude mineral (containingmoisture) is fed from a suitable bin 4 to a preliminary milling machine 5 which in this case may be spiked rolls. The partly crushed mineral may then be fed through a tourniquet, scroll, or other feeding device 6 into an enclosed milling or disintegrating apparatus 7 of any appropriate design, for example, a swing hammer mill, from which the milled material is discharged by suitable means such "as pipe means 8 into a fan, blower, or disintegrator 9 adapted to the conditions. This blower or disintegrator discharges the milled material through pipe means 10 into an air separator or cyclone 1 which is equipped with an outlet. means 2 through which all excess air or gas or other fluid may be discharged. The base of the cyclone or separator 1 into which the milled mineral settles, may be provided with a tourniquet, scroll, or other feeding device 12 which discharges from means 13 into suitable pipe or gylindrical means 14 which constitutes a drying chamber, of requisite length and whichmay be made of cast iron, refractory tile, etc. A furnace, heater, or other sultable source of heated air, gas, o'rother fluid, for example, waste heat from another operation (provided such gas is at a temperature above 212 F.), indicated at 1-5 discharges into means 14 and the moist, milled' material from cyclone 1 is thereby surrounded or suspended in means 14 with a heated gas or drying medium. This mixture of milled material and gas is discharged into a blower or disintegrator 16 which in turn discharges through means 17 into a second cyclone air separator or other suitable device 2 wherein the suspended matter is separated from its gaseous carrier by a gravity gas-separation operation. The discharge pipe 18 from this second cyclone leads back to the milling or disintegrating apparatus 7 and thereby forms a closed circuit.

The above process and apparatus pertain directly to my invention and the dried and milled mineral maythen be discharged through suitable feeding device 19 from the bottom of cyclone 2 but inasmuch as it has been heated during the drying operation in its passage through means 14, blower 16, and means 17, it may \be desirable to cool said material before bagging or otherwise preparing the material for shipment. The milled and dried mineral may be, therefore, discharged from the base of cyclone 2 through suitable feeding mechanism such as a tournie quet 19 into means 20 leading into pipe means 21, provided with an inlet for cold air as indicated at 22. The finely divided and dried mineral matter is then sucked into a fan or impeller 23 of suitable design, and discharged through means 24 into cyclone 3, from whlch the coarser material is discharged through a valve, or scroll, or tourniquet, etc. 29, into stocking dust collector made of tubular fab-1 ric open-end containers, through which the air is blown, the dust being left on the interior of said tubular membranes, Eventually the dust fallsto the base 28 of said stocking dust collector and may be withdrawn therefrom periodically and also bagged or otherwise prepared forshipment as a distinct and exceedingly fine grade of material.

The temperatures of the gases discharged into the atmosphere from the separating chamber 1 must not be too high, else a certain amount of very finely disintegrated material is lost through this outlet. The temperature of the exhaust gases at which the most effective operation takes place varies with the percentage of moisture in the crude or raw material being treated, the temperature to which the material is heated, the percentage of moisture in the material entering that separating chamber which exhausts into the atmosphere,

and the velocity of the gases. For example. in the manufacture of disintegrated or finely divided dlatomaceous' earth from natural diatomaceous earth, which originally con-' cal conditions; that is, the degree of milling v and velocity of gases was kept constant. Temperature of the gases going through blower 16 were approximately 500 F. while the gases being returned to the primarydisintegrator 7 were about 225 so that somedry- 10, since the finely divided moist material is held in suspension for a substantial period of time in these means. Supplies of heated gas may be introduced at disintegrator 7 or to pipe means 8', in addition to the gases introduced by heater or other source15, whenever the material being fed into the system at 4 contains very large quantities of moisture.

Referring to Fig. 1, it is seen that the gas discharged thru the exhaust 18 from chamber 2 contains dust which is absorbed or retained by the moist material disintegrated in the mill 7 and that there is no dust loss from exhaust 11 from chamber 1, by reason of the moisture resent in the material at this stage, also, as above noted, this gas is heated and terial in the mill.

mg action also took place in means 8, 9, and

calcining zone.

much'the same manner as described in Fig. 1. The calcination disclosed by the following modification-may be made on the raw, disins tegrated mineral either with or without the addition of suitable salts or chemicals; for

' example, it has been found that calcination of finely divided diatomaceous earth 7 in the presence of salts of alkali metals produces a white, flufly, and very desirable product.

In Fig. 2 the raw mineral is fed from a bin 55 or other suitable source of supply, to a suitable crushingcnachine 56, for example, spiked rolls. The partly disintegrated mineral is then fed by a suitable mechanism 57 (which may be a scroll or belt conveyor), to an enclosed disintegrating apparatus 58 which may be a swing hammer mill or the like. The disintegrated mineral is then passed by suitable pipe means 59 through a fan or impeller 60 (which may be so designed as to give a certain amount of disintegrating action), through pipe means 61 to a suitable aii;- separating chamber 51. said air separating chamber discharges into the atmosphere while the disintegrated material discharges from the air separatingchamber 51 through a tourniquet, scroll, or other suitable means 62. into and through pipe means 63 into pipe means 64, which lead to -a fan or impeller 65., The last mentioned fan discharges, through pipe means 66 into a secondary air separating chamber 52. The

gas containing fine particles of matter is discharged from the air separating chamber 52 through pipe means 67 and lead back to the closed chamber con taining the disintegra-i tor 57. v i

The disintegrated material from air separatin chamber 52 is discharged through a suitab efeeding mechanism 68 which may be a tourniquet, scroll, or the like, into pipe means 69, which discharge directly into a tures employed.

suitable chamber 70 in which the materialis subjected to a calcining temperature. The chamber 70 may be made of any suitable material capable of withstandin the tempera- For examp e, it may bti made of'fire clay, tile, or brick,'0r it may be made of a heatresistin metal. Chamber 70 is connected directly with a source of heat 71" which may be "an auxiliary furnace, having a mixing or combustion chamber, into which a draft of diluting air or air to support com- The exhaust 51' i from.

bustion is supplied by means of blower 73.

One furnace used by me had preheating passages in the furnace walls with adjustable openings so as to give thorough control of air inlets and give complete combustion. A

feeding mechanism 72 may discharge into said fan 73 to supply salts of alkali from metals, although such salts may also be introduced at any other point in the system, for example, at 68. In passing through chamber 70 the hot gases calcine or either heat the disintegrated material and discharge into a third air separating chamber 53, from which the hot gases are discharged through pipe means 74 into-the above mentioned pipe means 64. The newly calcined, finely divided mineral contained in air separating chamber 53 is discharged through a, feeding valve or,

mechanism 75 into pipe means which lead into pipe means 77 ,which in turn discharge into a fan or impeller 78 which discharges into a fourth air separating chamber 54 by means of pipe 79. Fan or impeller 78 may have a means of admitting cold air thereto as indicated at 76 so as to further, cool the recently calcined material discharged from chamber 53. Chamber 54 discharges the finely divided calcined mineral through a feeding mechanism such as a tourniquet 84 into a storage bin or other suitable receptacle 85, from which such material may be withdrawn through means 86 for bagging or other disposition. The gases leaving the air separating chamber 54 through plpe means 80,

such gases containing exceedingly minuteparticles of mlneral matter, are led into a suitable dust collecting or air separating system, such as is indicated at 82, and which ma be a stockin dust collector in which the minute partities are retained and collected in the bottom of said collector in bin 83.

' It is to be remembered that Figs. 1 and2 are merely diagrammatic representationsof the fundamental ideas embodied in my invention and thatthe angle at which the various pipe means connect the units may be varied to a large degree, and the number or location of fans or impellers may be changed with the conditions encountered in practise. For example in Fig. 2, the calcining chamber 70 may be placed vertically and the calcined material discharged into a fireproof storage in which it is cooled before being passed through air separating chamber 53 or 54 or both. The addition of salts or alkali metals during or before the calcining operation is ly divided mineral matter may be accomplished without such salts. Furthermore,

the fans or impellers used in this invention may readily accomplish a certain amount of milling or disintegration, particularly when an easily reduced mineral, such as diatomaceous earth, is being treated. Whenever fans 'not necessarily followed in. all cases, inasmuch as a purely calcining operation on fincearth by or impellers are therefore specified they may be understood to function not only as means of blowing but also as secondary disintegrators.

What is claimed is: 1

1. In a milling and drying process, the prevention of dust loss by disintegrating material containing moisture, passing such dis-- integrated material by pneumatic means into a separating apparatus, discharging the substantially dust-free air from such separating apparatus, discharging the disintegrated material from the separating apparatus into a heated gas, passing such gas and disintegrated material into a second separating apparatus and circulating the partly spent gas containing dust from the second separating apparatus to the moist disintegrated material.

2. In a combined milling and heating process the prevention of dust loss by disintegratlng material containing moisture, passing such disintegrated material by pneumatic means into a'separating chamber, discharging the dust free gas from such chamber into the atmosphere, discharging the milled material from such chamber into a current of heated gas, conveying the milled material and gas'to a second separating chamber and discharging the dust laden gas from such second chamber into the moisture-containing material so as to conserve such dust.

3. In a combined milling and heating process employing disintegrating apparatus, and

primary and secondary air separating chambers, the circulation of partly spent heated gases containing dust from the secondary air separating chamber to the disintegrating apparatus so as to conserve such dust, and dis charging dust free air from the primary air separating chamber.

4. In a combined milling and heating process, the prevention of dust 'loss by disintegrating diatomaceous earth containing. moisture, passing such disintegrated diatomaceous pneumatic means into a separating chamber, discharging the dust free gas from such chamber into the atmosphere, discharging the milled diatomaceous earth from such chamber into a current of heated gas, conveying the milled diatomaceous earth and gas to a second separating chamber and discharging the dust laden gas from such second chamber into the disintegrated moist diatomaceous earth so as to conserve such dust.

5. An apparatus for disintegrating and drying minerals Without loss of dust comprising a substantially enclosed disintegrator, 'ineumatic means of conducting disintegrated mineral to an air separating chamber, gas discharge means from said chamber and discharge means for disintegrated mineral from said chamber leading to a source of heated gas, means of conducting such heated gas and disintegrated mineral to a second separating means of conducting moist disintegrated diatomaceous earth to an air separating chamber, gas discharge means from said chamber and discharge means for disintegrated diatomaceous earth from said chamber leading to a source of heated gas, means of conducting such heated gas and disintegrated diatomaceous earth to a second separating chamber, and means for conducting the dust containing gases fromsuch chamber into the moist disintegrated material.

7. The herein described process of removing dust from dust laden air or gases produced in the milling and heating of moist siliceous material and the like; consisting in milling the siliceous material, heating the milled material, and. returning the dry dust laden air or gases produced by such treatment into the moist material being treated previous to the drying thereof, whereby the dust is deposited on and retained by the Wet or moist material.

and drying moist diato-maceous earth, con- 7 v sisting in first disintegrating the raw diatomaceous earth, discharging the disintegrated diatomaceous earth into a suitable heater; and returning the dust laden gases or air produced by such treatment into the moist diatomaceous earth being. treated before the latter reaches the heater.

9. In a combined milling and heating proeess, the prevention of dust loss by disintegrating moisture-containing diatomaceous earth, passing earth y pneumatic means into a separating chamber, discharging substantially dust-free gas from such chamber into the atmosphere, discharging the .milled diatomaceous earth from such chamber into a current of gas at a temperature above 300 F., conveying the milled diatomaceous earth and gas to a second separating chamber by pneumatic means, and discharging the dust containing gas from such second chamber into the initial disintegrator containing moisture-containing material so as to conserve such dust.

10. A continuous process for the combined milling, drying, and separating of moist mineral materials and the like which comprises milling the moistmaterial to reduce it to a finely divided form, suspending the finely dividedmaterial in a heated gas whereby drying of the suspended particles is effected, subjecting the gas With the dried particles suspended therein to a gravity-separation operation to separate the dried particles from the gaseous carrier, passing the dust laden such disintegrated diatomaceous gas resulting from said separation operation into contact with moist material treated in the milling operationto retain the dust and utilize any available heat in the gas for par- ,tial drying of the moist material, continuously withdrawing moisture laden gas from the system, and replacing said withdrawn gas by gas heated to an elevated temperature and I terials and thelike comprisin moist material to -reduce it to nely divided adapted for drying,

11."An apparatus for the combined mill ing, drying, and separatingof moist mineral materials and the like, which comprises a disintegrator or mill forreducing thema terial to a finely divided form, a drying chamber for drying finely divided material from the mill while suspended in a heated gas, a gravity gas-separating device tor separating the dried material from its gaseous car- 'rier, and means for conducting dust laden gas produced in said separating device to the dlslntegrator thereby forming a closed c1rcu1t, and means for supplying heated gas to said circuit. I

In a process for the combined milling, drying, and separating of moist mineral mamilling the form, suspending the finely divided material in a heated gas whereby drying of the sus pended particles isveiiected and separating the drled material from its gaseous carrier 'by a gravityseparation operation, the imti'al drying of the moist material.

13. A process for disintegrating, drying,

and separating moist mineral materials and. the like which comprises, milling "the material to reduce it to a finely divided form, suspending the finely divided material in a current of heated gas whereby drying of the suspended particles is effected, and subjecting the gas together with the dried particles suspended therein to a gravity separation operation whereby the dried particles are collected and separated from the gas.

14. A process for disintegrating, drying, and separating moist mineral materials and the llke which comprises, milling the material to reduce it to a finely divided form, suspendin'glthe'fin'ely divided material in acurrent of eated gas whereby drying of the suspended particlesis efiected, and passing the; as together'with the dried particles suspended thereln thru a gas separator of the cyclone type whereby the dried particles are collected and separated from the gas.

15. A process for disintegrating, drying, and separating moist mineral materials and the like which comp-rises, milling the material to reduce it to a finely divided form, suspending the finely divided material in a current of heated gas whereby drying of the suspended particles is effected, subjectin the gas together with the dried particl therein to a gravity-separation operation es suspended whereby the dried particles are collected and separated fronithe gas, and passing the dust V laden gas thus separated into contact with moist material treated in the milling opera tion whereby the dust is absorbed on the moist material. v t

16. A process for disintegrating, drying, and separating moist mineral materials and the like which comprises milling the material to reduce it to a finely divided form, suspending the finely divided material in a current of heated gas whereby drying of the suspended particles is effected, subjecting the gas together with the dried particles suspended 'therein to a gravity-separation operation whereby the dried: particles are collected and separated from the gas, and passing the dust laden gas thus separated and still retainmg an elevated temperature intocontact with moist materialqentering the process Whereby the dust is absorbed on the moist material and partial dryin of said material eiiected.

17 A process tor the disintegration and drying "of moist mineral material and the like, which comprises milling the moist material to reduce it to a finely divided form,

forming a gaseous suspension of the finely divided particles by passing a current of heat ed gas thereover, maintaining the particles in suspension for a period whereby drying is afl'ected, and subjecting the gas having the suspended particles therein to a gravity:

separation operation whereby the gas andv the suspended matter are substantially separated. g

18. An apparatus for the disintegration and drying of mdist mineral material and the like, which comprises a disintegration or mill to reduce the material to a finely divided form, means for introducing a'current oi heated gas into the disintegrator to produce a suspensionof the finely divided particles,

a gravity gas-separatorto separate the sus-- pended matter from its gaseous carrier, and

s a conduit connecting said mill and gas-sepa rator for conducting the gas having the suspended material therein from said mill to they.

gas-separator and for maintaining the, susension for a suflicient period of time to efect drying of the suspended matter. I

19. An apparatus for the disintegration and drying ofmoist mineral material and the like, which comprises a disintegratoryvor mill to reduce the material to a'finely dii vided form, means for introducing a current of heated gas into the disintegrator taproduce a suspension of the finely divided particles, a 'gravity gas-separator to separate the suspended matter from its gaseous carrier,

a conduit connecting said mill and gas-sepa rator for conducting the gas having the suspended material therein from said mill to the gas-separator and for maintaining the suspension for a suflicient period of time to efl'ect drying of the suspended matter, a discharge'pipe, inter-connecting said separatorand said means for introducing heated air, to conduct heated dust laden gas from the separator to said means. i

20. An apparatus for disintegrating, dry- 'ing, calcining, and separating moist mineral materials and the like which comprises, a disintegrator or mill for reducing the material to a finely divided form, a drying chamber for drying finely divided material from the mill while suspended in a heated gas,a

gravity gas-separating device for separating the dried material from its gaseous carrler, a chamber having heatlng means associated therewith, for receiving and calcining the dried material from said separator, and

means for introducing hot waste gases from iaid calcining'chamber into the drying cham-' 21. An apparatus for disintegrating, drying, calcining, and separating moist mineral materials andthe like which comprises, a disintegrator or mill for reducing the material to a finely dividedform, a drying chamber for drying finely divided material from the mill while suspended ina heated 'gas, a gravity gas-separating device for separating the integrator or mill for reducing the material to a finely divided form, a drying chamber for drying finely divided material from the mill whilesuspended in a heated gas, a gravity gas-separating device for separating the dried material from its gaseous carrier, a

chamber for receiving dried material from said separator, means for passing .a current of hot gas thru said chamber into contact with said dried material to produce calcination thereof, a gravity gas-separating device for receiving the hot gases discharged from sald calcining chamber and for separatlng calcined material carried in suspension therein, and means for introducing the hot Waste gas separated in thelast mentioned separator into the drying chamben' In testimony whereof I have hereunto subscribed my name this 1st day of Dec. 1928.

McKIJNLEY STOCKTON.

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