US2983453A

US2983453A - Method of pulverization

Info

Publication number: US2983453A
Application number: US721162A
Authority: US
Inventors: Jean M Bourguet; Robert D Drew; Louis P Evans; Jonas P Harrison
Original assignee: Socony Mobil Oil Co Inc
Current assignee: ExxonMobil Oil Corp
Priority date: 1958-03-13
Filing date: 1958-03-13
Publication date: 1961-05-09
Anticipated expiration: 1978-05-09
Also published as: DE1254440B

Description

J. M. BOURGUET ErAL 2,983,453

METHOD oF PULVERIZATION May 9, 1961 Filed March 13, 1958 2 Sheets-Sheet 1 FRESH; FEED HUMIDIF'IED l Hann/uws 2 Sheets-Sheet 2 METHOD OF PULVERIZATION J. M. BOURGUET EIAL /G/ xmms. man 103011... w\ Imm Om\ V^\ Imm Z MMWV\\ W\ \\\m May 9, 1961 Filed March 13. 1958 .LNE-LNOU EUQ'LLSiOl/Q BY ATTO ' t to improve the eciency of a uid jet pulverizing operaf 1 tion of the type hereinabove described. Another object y 2,983,453 of the invention isto increase the capacity of'a pulverv izing apparatus'utilizing fluid jet action to-faiord'a highf METHOD 0F PULVERIZATIQN 5 throughput of materialunde'rgoing treatment. A furtherl Jean M. Bourguet, Woodbury, Robert'D. Drew, Weno- Objectis to provide a method fortreating'a4 feedcharge nah, and Louis P. Evansraud Jonas P. Harrison, Wood'` of solid, porous, pulverulent vmaterial by. exposing the bury, NJ aSSglOlS t0 SMOBY M0bil 'Oil COmP'mlya 'same to the'energy of high Vvelocity fluid jets in a man'- 'Inco 3 @mongol 0f New York ner to accomplish size reduction of said charge material Filed Man 13;,195'8 serjNm 721,162 l 10v by the combination of explosive forces, as Well as vby the j j j aforementioned particle impact and attrition.' A very 5 Clallls- (Cl- 241-1) .t important vobject 'of the present invention is the provision of a'method for increasing the grinding capacity Y v 1 of a pulverizer of the type described in which the ma- This invention relates to an'improved methodffor 15 terial to beground is aV porous, friable adsorbent solid.

effecting pulverization of fragmented solid porous friable having a pore volume fraction of at least 0.1. The material. More particularly, the present invention is term po-re volume traction, yas utilized herein, desig- -concerned with a method for increasing thecapacity `or nates the fraction of total volume of a porous solid which Vthroughputof a pulverizer wherein solid pulve'rulent feed is attributable to the volume of the pores therein. material in the form of small particles is ground to a 20. j The above andothe-r'objects which will be apparent predetermined size by the action of jets of gaseous ud to those skilled in the Yart are realized in accordancl' introducedatsuperatrnospheric pressure into a confined v with the method of this invention. Broadly stated, the zione containing said material, causing the particles of` present invention affordsva method for increasing the said material .to be entrained in the atmosphere of said eiciency of a jet'pulverizer to achieve greater throughgaseous uid and to be recirculated to such jets until put by control of the particle size'and moisture content reduced to thedesired degree of neness. j t of the solid, porous,` pulverulentl charge material under- Pulverizers of the type, to which the present invention, going' treatment in said pulverizer. Thus, it has been is applicable, involve thoseadapted'for pulverizingsolid discovered, in accordance with the present invention, materials by Huid iet action. In such pulverizers, jets that the rate in production of finely divided material of gaseous uid are introduced at high velocity into lan 30 of predetermined size can' unexpectedly be increased annulargrinding zone, which grinding zone contains the by 'controlling the particle size of the porous charge ma-V material to bepulverized inrthe form of discrete small terial to Vgreater than about 200, mesh (Tyler) and by particles. An atmospherefof gaseousVv iuid is produced controlling the water content or said porous chargeI andrnantained as the consequence of the 'operation of rnateriahin` an `.amount 'not in excess of that correshejets gnl'allywth Superheafed Steam 0f COIIPTCSSed pondinggto the pore-volume fraction of said material, air. Whenv the nature of the material to'be ground Itf` but sufficient tor bring about sudden Vexplosion of the 'CIUI'S it, other QOD'IPI'SSQ@ gases, Such 'SzfT Kampl? controlled size particles of the Vsolid porous charge ma-v Cl'bbll dOXd 0f HUTOCIIIIIZY llllseflfk These gaSeOuS terial when the. same are subjected to elevatedl tem y' lowpredeterni-ined size, ranges;.iscontinuously eXhausted uds" UCIUSVeOf Such VaPOl'S-fasmay b@ Present in' perature insthe A. grinding zone substantially in excess of Spirale the Particles 0f S01id m?1te.al which are @be thetboiling'pointof waterand, generally at least about.

ewund and Cause-'themto be Suspend in .the Streams sofgF. above lwid boinngyloim. .The contact of the* Qf gaseous id-and PamlQS-SO createdv wva'ter-containingil charge .particles with .the grinding uid The high V610 ity, fluid jets rf? gePerauY-dlfctedfor at suchfelevat'ed temperature causes theA particles to ex- Wafdv'ir Q9? directas@ mail@ efe afdvrf 45 moderne to. sudden evaporation@ the watenfrhffhe of paltlcllfz ,Of-g m'flnftl un??? treatmfen-ft-Hbyr lm, rptparticles. Thenexplosive forcesrthus'generated, in compac-.t 'and -a-mmon O,- sr agtn'sthgpg dq' er an binationWith,the,-no1mal grinding action ofthe jetl pulagam-St the* chamba-"walls"enclosmg "t e m'mg Zone" veri'zerrhas,"in-accordanceegwith the-present invention,\ Y been' tfoundto'lresult inifa 'considerable increase iny throughput'of the pulverizer. t

rection ofthe;circulating,fluid .Diieltolthel rotationalr il effects resulting frm the rapid 'circulationA of Lthe/,charge within thegrindingzonerthe largerparticles are caused' to concentrate in such; )Zonel where they ortie' repeatedl vvIn s "ne -emb' diffrent, "thev present t. invention is :directed :'ed'uction iin.particle'sizeof partially comminuted; 'v erulent"solid"having'A alp'article isizel greaterf a jet pulverizer by' conf l solid Piorto its intro-V sufnciemiy manfred ige- 1 actiona produced.,` `The mate from the gn'ndingvzpneibyentrainment ,inlthe gaseou'szfx y fluid l'eavingthe same.H Comfninutionuandfgr Y ding, aso indicated, (take Placet'ogaconsiderabledegreein such rmlverizing OperationibilftheAeiemiy'mengt-'may .be` improvedl inaccordanceV with rthe presentfinvention --t the attainment vkof" paneles for@ extremely miute. lsiZeSg-*65 A zeolites.

rected to a method for effectively grinding to an average particle size of less than 10 microns, a solid, porous, riable material having an initial particle size in the approximate range of 2 to 200 mesh (Tyler) and a pore volume fraction in excess of about 0.1 in a pulverizer utilizing uid jet action and provided with a grinding zone maintained at least 50 F. above the boiling point of water by controlling the water content of such charge material to an `amount of at least l percent by weight but insuicient to produce an aqueous slurry of said charge material.

In a further embodiment, this invention is directed to a method forincreasing the throughput of a porous, friable, particle-form solid in a jet pulverizer wherein such solid is subjected to the grinding action of high velocity jets of gaseous fluid at a temperature generally in the `range of 300 F. to 600 F. by'conducting to said pulverizer a charge of said solidof 2 to 200 mesh size (Tyler), suspended in a stream of said fluid and having a minimum water content of 5 percent by weight.

in a still further embodiment, this invention is directed to an improved method for grinding a porous inorganic4 oxide gel characterized by an initial particle size of between about 2 and about 200 mesh (Tyler) and a pore volume fraction in the approximate range of 0.1 to 0.9 and a water content between about and `about 90 percent -by weight by subjecting the same `to the grinding action of high velocity jets of steam in a confined zone of a jet pulverizer maintained at a temperature between about 300 F. and about 600 F. to effect reduction in thek average size of said introduced gel particles to less than about 10 microns.

The' charge material undergoing pulverization in accordaince with this invention is a porous, friable solid, generally characterized by a .pore volume fraction in excess of about 0.1 It is contemplated that any solidrnaterials meeting the Vabove ldefinition may be effectively treated by the method of the invention. Representative materials include clays, activated carbon, porous metals, porous glasses, gelatinous precipitates, gels and the like. Inorganic oxide gelsware particularly suitable as feed materials for pulverization in accordance with the method described herein. The particular chemical composition of the gel feed or other material does not appear to be critical. Thus, gels of silica, alumina, molybdena, magnesia, chromia, zirconia, thoria, titania, manganese ox# ide and composites thereof are suitably pulverized by the present method. .The resulting pulverized material gen erally having an average particle size of less than l0 microns and more usually in the range of 1 to .5 microns is useful in the form of or in the manufacture of catalysts, catalyst supports,` adsorbents, desiccants, and

` Onthe other hand, the physical characteristics of 'the' charge material are important to the success'of the 'method ofthe invention. Thus, the charge material should necessarily-be of a porous pulverulent nature and have sufficient porosity such that the Hquantityl of adsorbed water willE charge material.

tainable by following the methodof the invention. Thus,

it has been established, in accordance with the present invention, that an increased throughput of porous pulverulent solid material may be achieved in a jet pulverizer with an increasing Water content of such material provided that the particle size of the feed material to such pulverizer is maintained greater than about 200 mesh (Tyler). When the particle size of the lfeed material is liner than about 200 mesh (Tyler), it has been observed that the throughput of such material unexpectedly decreased with an increasing water content. It is accordingly an essential and critical `feature of the invention that the particle size of feed material be greater than about 20() mesh (Tyler). Under normal conditions of operation, the particle size of the feed will be in the approximate range of 2 to`200 mesh (Tyler). The reason for the above notedreversal phenomena is not, known with certainty. It would appear, however, without being limited by any theory that particles of feedmaterial liner than about 200 mesh in the presence of adsorbed water have the tendency tocohere or stick together requiring a lfurther grinding effort to obtain the desired product of predetermined line size and thereby imposing a greater burden on the jet pulverizer with ,the consequent `observed decreasein the rate of throughput.V

The water content of the particle-form charge material is necessarily sufficient to effect explosive shattering of the particles -due to sudden Vevaporation of such water upon contact with the gaseous iluid at the elevated temperature prevailing in the grinding chamber of the jet pulverizer. Generally, the amount of water present is at least about 5 percent by weightV but not in excess of an `amount of waterrcorresponding to the pore volume fraction of the More-particularly, the minimum water content of the charge material will be about 10 percent by weight, usually within the approfximate'range of l0 to 90 percent. by weight and preferably between Vabout 20 and about 40'percent by weight. Itfwill befunderstood tha't the amount of water.v in each instance, however, is less than an amount equivalent to the pore volume fraction of the charge material so that all of the water .present is in an` adsorbed state. An aqueous slurry rof the particle-form charge material, )for examplerhas not been@ found to be suitable for accomplishment lof the'objectives'y of the invention sincel the lparticles in the form of ysuchf slurryl are not, ar'nenabl'el to the sudden evaporation .of' waterA with accompanying explosive shattering.suoliasA achieved i'n thevmethod of the'invention.' "Thewater con! tent of the charge'materialcan bei controlled,in"any`s1it able 4manner either by dryingV the charge material `to the requisite water' content or by the addition'- of Water tov the charge materialgbefore the same enters the-grinding chamber of; thejetpulverizen :for example,by the', ad-V dition of water to theffe'ed'-lineenteringsuch chamber.

upon sudden evaporation thereof upon exposurev to ele'.

vatedtemperatures prevailing inthe grinding chamber be suticient to causeexplosivev shattering of such jmateriala The material undergoing pulverization generally has a, pore ,volume fraction. greater lthan about l01 @andrnoref usually within the approximate range of.0.l to0.9. l,r' 1he particle size of theporous charge materialshould neceseen established,`"as *willl be evident from data pre?v ed hereinafter, that if the 4partielesize ofthe porous ,charge material is finer thaniabout 200'rmesl1`, the'effect'f of'wate-r contentof the charge lmaterial. on'the rate. ofiV throughput of such material in'th'e-j'et pulverizer lil-ien# pectedly `hasea vreve'rsedor- 'opposite' effect'from 'that lobcontenti'. ,i t

VThe water' may be rfadded 'in' ay controlled amount in 'the' form ofpasprayforfa'sla contnonsstream'ofliquid 'mixed inthe yfeed line 'with the particle-for'ml charge." 'Alter-r, natively, Vthe, particlesbf charg'e 'material may 'befcon- .tacted,eithe`r' onV a'sttic or continuous-basis, with highly humiditiedA `a'ir toaiford a" product` of therequisite'water t"fl`he particle 'f charg'ematerialcontainingadsorbed:

' water tlienenterstlie grindingchafnbervof a jietpnlveriz'enf il suitably L 'suspendedV "in" a; stream" of the gaseous "ginding vllui'd' a't' ahighvelocitf where" it islthrown in theV radal path of `lthegrinding,iiui'd eritering'said chamberjat aftenif" perature 'aboveftheboilirrg lpoint of waterahd gen-rally,i ati'aV temperature sumcientlyhight" effect :sudder'if eya'pdfration of theadsorbediwater-wtih accompanying e'rplofsifl'eA sfiaftterir'igV A he particle eharge-'btat atemperture lliiid'ente'ring 'the grinding `chamberwithin the-vrange duced to a 'predeterminedl degree of neness.

Example 7 Gel product'- prepared as in Example 1 was preground Vto D/150 mesh and huinidified in air to Ya Water content of l'6 percent by weight. The resulting material after pulverizing under-conditions identicalwith those of Exa'rr'lplt;A 2; showeda production'of 4.5 micron size material of 'aliout pounds per hour. i

' "Gel product prepared as in Example lwas preground to a particle size' smaller than 325 mesh and thereafter humidiiiedto'a water content of 27 percent by weight. The'resulting material after pulverizingunder conditions identical with those of Example 2' showed-a production off about 3.35 pounds per hour.

` Example i 'Gel p'roduct'-V identical with that'of Example 8 was 'humidied to a water content of 16 percent by Weight. The resulting material after pulverizing'under conditions identical with those of Example 8 showed the production of lll-S'rnicronV size material of aboutv 4.2 pounds per hour. The'results of the foregoing illustrative examples are shown graphically in Figure 3. ItA will be noted from such iigure that the production index i.e. the production of 4;5V micron si'z'e material in'pounds per hour increases with increasing moisture content utilizing a charge material having a particle sizeof 24/ 35 mesh. Likewise, the production index for Vcharge material lhaving la particle size of 10,0/'150 meshiincreasedjwithan increase in moisture content. The: charge vvmaterial having a particle size sniallerlthan 32,5 mesh; however, gave a smaller productionrindex with increasing moisture contentindicating that the-rate of throughput of` such charge material in the jet pulverizer. decreased as the Water content thereof ine creased. This, aswill be apparent, is the exact opposite of the effect observed with charge material having a particle size of 24/ 35 mesh `and`-l0O/`l50 mesh. l It is 'accordingly essential'to thegsuccessof themethodof Ithe invention 'that the particle size of the charge materialbe largerthe boiling point of water, causing the particles of' said material to he entrainedy in the atmosphere of saidV gaseous fluid and to be recirculated to such jets until reduced to a predetermined degree of tineness which comprises introducing to' said pulverizer, particles of said material of a size greaterthan about 200 mesh characterized by a Water contentY in an amount not exceeding that corresponding to the ypore volume fraction or said material but sufficient to etlect explosive shattering of said particles' upon contact with said gaseous fluid maintained at said elevated temperature in said grinding zone.

3. A method for increasing the throughput in a jet pulverizer of a porous, friable, particle-form solid feed material having a pore volume of at least 0.1 wherein'sfaidfeed material is subjected to the grinding action of high velocity jets of gaseous fluid in a confined zone maintainedV at a temperature at least 50 F. above the boiling point of water, causing the particles of said material to be entrained in the atmosphere of said gaseous fluid and to be recirculated to said jets until reduced to a predetermined degree of neness which comprises introducing to said pulverizer, particles of saidmaterial of a size between abouty 2 and about 200 mesh characterized by a Water content o'f at least about 5 percent by weight but not in' excess of an amount corresponding to the pore volume fraction of'said material.

4. A method for eftectinga reduction in the particle size of inorganic oxide gel particles characterized by an initial particle size of between about 2 and about 200 mesh Vand a` po're volume-fraction in the yapproximate range of 0.1 to 0.9 and a water content between about 10 andV about 90 percent by weight whichcomprises introducing-*said particles of gel to a jet pulverizer wherein said gel particles are subjected to the grinding action of high velocity jets of gaseous iluid in a conned zone maintained at a temperature between about 300 and about 6Q0 F. to" eectl reduction in the average size of said introduced gel particles to less than l0 microns.

5. A method'for effecting a reduction in particle size of partially comminuted porous pulverulent adsorbent solid having a particle size in v'the approximate range of 2 to 200`mesh ina jet pulverizer wherein said'solidis subjected to the grinding act-ion of high velocity Vjets of gaseous fluid in a com'ined zone which comprises controlling the Vwater content` of said `solid prior to its'introduction to'thefgrinding' zone of said pulverizer in an amount of at leastabout 5 Ypercent by weight but not exceeding an amount equivalent to the pore volume fractionof the porous solid, introducing the solid of such o'l'par'tially comminutdjporous pulveulerit solid having a I solidpror toitsy intro uc ion-'to he grinding zoneof said pulverizeiif in-an""ani'ou`ritiof at least"about5fpercent;byV Weight but not exceeding an amount equivalent to the pore volume yfraction ofth'eprous solid, introducing the solid of such controlled moisture content.to-thegrinding f particlel size greater `thanabout 200 mesh in a jet pulver l izerivlherein said solid is` subjectedftoffthe grinding action 'e'locitiy jets" rif-gaseous*fluidina 'contined zone controlled'moisture contenttothe grinding zone of said pulverizer maintainedl at' atemperature within the 'approximate range of 300 lto 600 F. thereby effectingexplosiveshattering of saidiparticles ydue to the Asudden evaporation-ofjthe. water from said particles 'andthereafterl subjectingfthe. shattered. particlesztolimpact and attrition attributable 1to'the'frotational action of-saidthigh velociy jetsV until-"said solid; is reduced .to 'a `predetermined `degree otn'eness. f i. y;

-6. A method for. increasing thethroiughput. ofaporous inorganictoxdejgelhaving a pore volume fraction in the` range of1 l to 0.9 in' a jetplllvcrizer whereinfsaid gel is" 660 vwhich-comprises.introducing to said pulyerizer,. particles of s'aidyv gel of a'.s ize within .the approximate range of Y2 to200 meshcharacterizedbya watercontent, between' about ZOfand aboutAQpercent byweigh excedingfan arnuntcorrespondingte. thepofrevolume;

fraction of vsaid ge'lftherebyfeftecting explosive shattering 0f l said gel' particles upon. contact,with saidgaseous fluid `vt t'giittblel othefro atonal 'actionr of said high velocity 1 jets to yield a resulting 'product subj tingtlie shattered gelA particles, Y

having an average particle size Within the range of 1 t 5 FOREIGN PATENTS mcrons Y 528,163 Great Britain Oct. 23, 1940 References Cited in the le of `this patent OTHER REFERENCES y UNITED STATES PATENTS 5 ultrafine Grinding and ciassicatinn with Fluid Jet 2,032,827 Andrews Mar. 3, 1936 Pulverizers, by M. F. Dufour and I. B. Chatelain, Mining 2,392,866 Stephanoff I an. 15, 1946 Engineering, March 1952, pages 262264. 2,393,783 Kridel Jan. 29, 1946 Comparison of Fine Sieves, RJ. 3766, United 2,515,541 Yellott July 18, 1950 10 States Bureau of Mines, July 1944, page 3.

2,636,688 Singh vApr, 28, 1953 7 2,856,268 Young Oct. 14, 1958