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reamed May 3, 1938 ‘_ ‘ z,116,4i2, 1 UNITEDYSTATES, PATENT oFFicE ' 2,116,423 METHOD OF CBYSTALLIZATION AND CRYS TALLIZED PRODUCTS ‘Chester L. Baker, Berkeley, Calif., assignor to Philadelphia Quartz Company of California, Ltd., Berkeley, Calif., a corporation of Cali fornia I No Drawing. Application January 18, 1933, Serial No. 652,418 20 Claims. (01. 23-110) The present invention relates to an improved 551,785, ?led'Juiy 18, 1931, I have disclosed cer crystallizing process which is particularly‘ appli- tain ways and means for producing stable hy cable to systems where the solution from which drates of the alkali metal silicates, and the pres— the substance is to be crystallized is of a sticky 5 or syrupy nature and contains an alkali metal silicate. Such solutions though usually super saturated are difllcult to crystallize. My inven tion is especially applicable to the production ‘of crystalline hydrates of alkali silicates, although 10 .I wish it to be understood that the principles in ent invention, therefore, is somewhat in the na ture of a modi?cation of or improvement upon U1 the processes therein claimed. In this particular held the primary object of the present invention is to produce the desired crystal species by means of a process in which the necessary control is ex ercised through regulation of the seeding opera volved might equally well be used in the producé tion without particular control of the tempera tion of mixtures of alkali metal silicates with tures involved. To state the matter in another way, I have now found that if a liquid of the ap proximate composition of the desired hydrate be ' seeded in such an intimate and thorough ‘man ner as to cause crystallization to proceed from other materials. , - 1 The invention also relates to certain new prod ucts o'r compositions of‘ matter as will further appear. ' The invention, to a large extent, has been de veloped in connection with the production of so dium metasilicate, and the present disclosure, 20 therefore, will relate in large measure to such ' material, but, as before stated, it is not-to be lim ited to this ?eld. \ ' v In the prior art relating to the alkali metal sili cates, where crystals, if any, have been produced, they have been contaminated with supercooled vor uncrystalnzed liquid to an extent sumcient to re sult in an unstable end product which, if ground, has heretofore tended to agglomerate into a solid . mass di?lcult to handle. . 1 With the foregoing in mind, the primary ob ject of the present invention may be said to re side in the provision of a crystallizing process in which the solution from which the product is to be crystallized is so thoroughly and intimately seeded, i‘. e., where the fool of crystallization are fool much more numerous than heretofore con templated, cakes and/or masses can be produced ' in which the conversion from syrupy liquid to crystalline solid is sui'liciently complete to yield 20 end products which are stable and free-?owing even if the crystallization takes place at ordinary ,ambient temperatures, which temperatures, of course, are considerably under the melting tem peratures of the crystal hydrates involved in the 25 present invention. Furthermore, my invention contemplates and makes possible a marked de crease in the time required to convert the solu tion into crystal form.v A statement of the more detailed objects of 30 my invention,‘ therefore. may be said to involve ‘ (1) the provision of a method for the production of crystalline materials by means of which it is - unnecessary to give any particular consideration to the control of the temperatures involved so long 35 so greatly multiplied and distributed throughout as the particular compound sought does not melt - the mass ‘as to result in the production of an ,or decompose; (2) the provision of a method in which the conversion from syrupy liquid to a crys end product which is substantially free or uncon taminated with supercooled or uncrystallizedma . talline solid is more complete than with previous :3 in terial so that in granular or divided condition the processes known to the art; (3) the provision of 40 a method in which the foci of crystallization are 1 enormously multiplied so as to bringall portions will not tend to agglomerate into solid masses. _ The new method of promoting crystallization of the liquid into intimate contact with a focus _ product will be stable, dry' and free-?owing‘ and herein disclosed mayalso be used ‘in connection with systems which contain constituents other than‘ those which it is desired to-crystallize, such as soap for example. More ‘specifically considered, my invention has for its object the provision of an improved proc ess for producing stable hydrates of the alkali of crystallization; (4) the provision of a method which results in an end product of ?aked charac 45 ter which will remain dry, stable add free-?ow ‘ ing in storage; (5) the provision of a method which will result in considerable saving not only in the cost of manufacture but also in the amount, of time necessary to arriige at the desired end metal silicates, notably sodium metasilic'ata. In ‘ product; (6) the provisionoi' a method in which." ~ my prior applications, Serial No. 465,245, (of the transition from liquid to solid form' takes which the present application‘ is a continuation ' place in a much shorter interval of time than has in part) ?led July 1, 1930, and issued as Patent been possible heretofore, which feature, of course, No. 1,898,707 on February 21, 1933 and Serial No. lends itself particularly well to the development 2,110,428 of a continuous manufacturing process; (7) the provision of a method of the foregoing charac ter whereby mixtures of crystallized materials ‘maybe prepared, which mixtures are also stable and substantially free of any tendency to ag glomerate; and (8) the production of certain new compositions of matter in stable form. Other plicable to the production of other alkali metal silicates‘ in stable crystalline form, as well as to mixtures of these with other materials, ‘such, for example, as sodium sesqui-silicate, sodium meta borate (NaBOzAHzO) etc. By way'of example sodium sesqui-silicate can objects and advantages will appear hereinafter I 10 or occur to those skilled in the art. Various examples of the manner in whch my improved method can be carried out are as fol’ lows: I.—Method of producing NazSi0s.5HzO 15 To 5000 grams of a solution of sodium silicate containing 8.84% NazO- and 28.8% SiO2 are add ed 1378 grams of caustic soda containing 76% NazO. The solution is then evaporated until the total weight is reduced from 6378 grams to 5090 20 grams. This hot liquor shouldv test just under 63° Bé. This solution is allowed to cool to any convenient temperature below 70° C. It is then placed on a roll type ink grinding mill and 500 grams of powdered NazSiOa?HzO crystals added. 25 The mass is then ground on the two primary rolls of the mill for about one minute. The discharge roll is then moved into place and the entire mass discharged onto the knife of the, ma chine. The product will be white in color and 30 quite opaque. Immediately upon cooling it will become hard ‘and brittle, so that it may be ground into a dry, free-?owing powder. In case the evaporated liquid has been cooled to room tem perature, the mass may be discharged from the 35 mill in the form of a very heavy paste which solidi?es almost immediately. ‘ ' II.—Method of Producing NazSiO3.6'HzO 40 To 4525 grams of a solution of silicate of soda containing 8.84% NaaO and 28.8% SiO2 is added . 1245 grams of caustic soda containing 76% NazO. The solution thus formed. is evaporated until the total weight is reduced from 5770 grams to 5000 grams. .The liquid is then allowed to cool to 45 any convenient temperature below 62° C. and I placed on the two primary rolls of an ink grind~ ing mill. 500 grams of crystalline NazSiOaGI-EO are then added and the mixture ground for one minute. The third roll of the mill is then moved 50 into place and the mass discharged onto the knife of the machine. Upon cooling the mass will become hard and brittle so that it may be ground to a, dry, free-flowing, granular powder consisting of crystalline Na2Si03.6HzO. 55 III.—Method of producing Nazsioaszizo To 4500 grams of a solution of silicate of soda containing 8.84% M120 ‘and 28.8% SiOz is added '. 1240 grams of caustic soda containing 76% NazO, and 410 grams of water. The solution is brought to a boil and the small amount of water lost by evaporation replaced, so that the ?nal solution _ has a weight of 6150 grams. This liquid is cooled to any convenient temperature below 47° C. The 65 mass is then ground for about 1 minute. The third roll of the mill is then moved into place and the entire ma‘ss discharged onto the knife of the machine. The discharged mass will be white and creamy in consistency. Upon cooling 70 it will become hard and brittle so that it can be ground'to a dry, free-?owing, granular pow be produced in the following manner: IV.-—Meth0d of producing NGaHSiO4.5HzO To 3300 grams of a solution of silicateof soda 10 containing 8.84% NazO and 28.8% S102 is added 909 grams of caustic soda containing 76% NazO and the solution thus formed evaporated to a weight of 3360 grams. This solution should‘ then test just under 63°Bé. This solution isthen cooled 15 to a temperature of 70° C. or below and 640 grams of caustic soda containing 76% NazO dis— solved in it. The solution thus formed is allowed to cool to any convenient temperature below 78° C. and if necessary 500 grams of crystalline 20 Na3HSiO4.5I-I2O mixed in. The mass is then placed on the two primary rolls of an ink grind ing roll mill and ground for one minute. The third roll' of the mill is then moved into place and the mass discharged onto the knife of the 25 machine. The discharged mass will be white and ' opaque in color and will almost immediately harden into a brittle mass capable of being ground to a dry free-?owing stable granular pow der. More often, however, the mass will be dis 30 charged from the machine as thin white ?akes which immediately harden and can be used in the arts without further grinding. In the foregoing example the seeding by the addition of the 500 grams oi’ crystalline NaaHSlO4.5H'2O may not be necessary because experience has shown that after a period of cool ing a number of crystals may sometimes form spontaneously and these can be satisfactorily dis persed by the grinding’ operation or its equiva lent. My improved process gives rise to an additional and very important advantage in that it makes possible a state 01' more intimate relationship be tween crystals prepared from solutions which 45 crystallize with difficulty and other substances which modify and/or increase their usefulness. For example, a mixture of sodium carbonate and the pentahydrate 01' sodium metasilica’.e may be made in which the two substances are pres 50 ent, the sodium metasilicate as a crystalline product while the sodium carbonate appears as an amorphous solid, although undoubtedly be ing ?nely crystalline. But the two crystals are so intimately interlocked that they appear to 55 the eye or even under a low-power microscope as a homogeneous mass. The same is also true of mixtures of crystalline alkali metal silicates and soap and of salt mixtures where two crystal species are formed concurrently, such as the 60 phosphate silicate mixtures, the silicate meta borate mixtures and the mixtures of the di?er ent hydrates of sodium sesquisilicate withthe hydrates of sodium hydroxide. This intimate re lationship prevents the possibility of mechanical 65 segregation of the mixed substances and thusv of one of them acting in any sense independent of the modifying e?’ect of the other. Caustic soda, for example, is an extremely corrosive sub stance, but in such mixtures as here contem 70 plated its corrosive effect is modi?ed by the pres-' ence of the silicate compound and it is much der consisting'of crystalline Na2Si03.9H2O. The foregoingexamples relate to‘ certain of safer to use. Some of the silicate compounds are v the sodium metasilicates, but it should be under 73 stood that the principles of the invention are 8P too actively alkaline for certain uses,'as in con tact with sensitive fabrics or human skin, and 75 3 . ‘ “3,110,423 the presence of hydrates of thus intimately related exerts a modify!“ ‘ ef in the product being‘at least 90 per cent crys tallized. fect quite beyond expectation in; vie'wpof“ the prop ‘ ‘erties ofthe materials separately. ' '1 Insofar as mixtures are concerned, theffollow ing examples may be taken as typical methods of procedure:—- . ' To 5000 grams of a solution of sodium silicate‘ - containing 8.84% M120 and 28.8% $102 are added 1378 grams of caustic soda containing 76% NazO.‘ The solution is then evaporated until the total weight is reduced to 5090 grams. The solution is then allowed to cool to any convenient tempera ' V.—Method of preparing a mixture of 10 NdapollzHzO and NG2SiO3.9HzO To 4500 grams of a solution of silicate of soda containing 8.84% NazO and 28.8% S10: is added ture below 70° C. and 500 grams of granulated 1240 grams of caustic soda containing 76% NaaO soap, together with ,500 grams of Na2SlO3.5H2O, added. The mixture is then ground on the two primary rolls of an ink grinding roll mill for 15 ' ‘and 410 grams of water. The solution is brought to a boil and the small amount of water lost by evaporation-replaced so that the ?nal solution has a weight of 6150 grams. This liquid is cooled one minute. The third roll is then moved into place and the mass discharged as a heavy paste. This mass will harden upon cooling so that it may be ground into a dry free-?owing granular and stable powder. 20 -VIII.--Method of preparing a. mixture of to any convenient temperature below 47° C. To the liquid is then added 1000 grams of crystalline 20. trisodium phosphate (NaaP0a12HzO) and 500 grams of ‘crystalline NazSiOailI-IzO. The mix ture is then placed on the two primary rolls of 25 ‘ VIL-Method of preparing a mixture of soap and NazSiOs.5HzO NazSz‘OaQHZOT and NaBOzAHzO an ink grinding roll mill and ground for one minute. The third roll is then moved into place and the mass discharged onto the knife of the machine. The discharged material will be white and opaque in color and usually in the form of To'2250 grams of a solution of silicate of soda containing 28.82% S102 and 8.84% NaaO are 25 added 620 grams of caustic soda containing 76% NazO and 630 grams of water. The solution thin white ?akes which become hard and brit1 ' formed is Just brought to a- boil and any water lost by evaporation replaced. tle almost immediately. At times the discharged harden almost immediately and can be ground to dry free-?owing, non-caking stable granular powder. 35 The solution is then cooled to any convenient temperature be low 55° C. At a temperature above 55° C. 30 mass will come oil as a heavy paste which will NaBOz.4H2O . This ground product is in the form of granules of interlocking crystals of NaaPOalZI-laO and Na2SiOa.9HzO, said crystals being interlocked dur ing growth, being substantially free from super so’ transforms into NaBOaZI-IzO and since the former compound is desired, it is necessary to maintain the temperature below 55° C. To the solution is then added 1850 grams of borax ' cooled metastable liquid and being, substantially incapable of mechanical segregation, the compo 40 sition as a whole being at least 90 per cent crystal lized and having substantially no tendency to agglomerate into solid masses. VI .—Method of preparing a mixture of NazCOs and NdzSiOa?HzO ‘To 5000 grams of a solution of sodium silicate containing 8.84% Na20 and 28.8% S102 are added 1378 grams of caustic soda containing 76% NaaO. The solution‘ is then evaporated until the total weight is reduced to 5090 grams. 2000 grams of and 390 grams caustic soda containing'76% No.20. This addition is brought into solution by stirring, 40 care being taken to prevent the temperature rising above 55?’ C. The massis then placed upon the two primary rolls of an ink grinding roll mill and 100 grams of Na2SiOa.9HzO and 100 grams of NaBO2.4H2O added for seed. The mixture is 45 ground for about one minute and then discharged from the machine as a white, opaque material which solidi?es almost immediately‘ to a hard brittle product which whenground will remain commercial sodium carbonate are then mixed in dry, free-?owing and stable upon storage. ‘The and the mixture allowed to cool to any convenient temperature below 70° C. 500 grams of productwill consist of a de?nite mixtureof‘ ' NazSlOaSI-IzO crystals are then added andv the mixture ground on the two primary rolls of an ink grinding roll mill for about one minute. The third' roll is then moved into place and the material discharged. as 60 a heavy, white, opaque paste which solidi?es upon cooling, to a hard brittle mass which can be easily ‘ ground to dry free-?owing'granular stable pow der. The sodium carbonate remains, unchanged during the above procedure and. it occurs in the . ‘product in its original state, usually considered amorphous, but known to be finely crystalline. The ground product therefore consists of granules of interlocking crystals of Nil-2C0: and. NaBOafiHzO and NazSiOsBHaO. ' 1. IX.—-Method of preparing a mixture of ‘crystalline. 55 1450 grams oi caustic soda containing 76% NazO are dissolved in‘5250 grams of a solution of , ' silicate of soda containing 28.84% S102 and 8.84% 60 NaaO. ' - ‘ ‘ ' The solution thus formed is evaporated to a ' weight of 5476‘g1'ams and is then cooled to'any convenient temperature below 30° C.vv 4555 grams of-caustic soda containing 76% of NazO are then 65. added and the mixture ground for one minute on the two primary rolls of an ink‘ grinding roll - mill. The third roll is then brought into position > and the mass discharged from the machine as a thick white opaque paste which hardens within 70 in a dry,» stable, .non-caking free-?owing state, a short period of time into a brittle mass which said crystals being interlocked during growth, can be easily ground to a ‘granular, free-flowing, being substantially free from' supercooled me ' stable powder. tastable liquid and being substantially incapable Many other mixtures can be made in a similar 75 of mechanical segregation, and the NazSiOaM-IaO 7 way providing proper consideration be given to 75 4 2,116,428 equilibrium characteristics. For example, com binations or penta or monohydrates or sodium sesquisilicate vwith hydrates oi’ sodium hydroxide maybe made. It should also be noted that certain combina tions of the hydrates may be produced as stable mixtures, and by way of example I desire to cite the following: X.--Method of producing a mixture of 10 _ NazSiOaSIhO and NGzSiOs.6H2O To 5000 grams of a solution 01' sodium silicate containing 8.84% Nazo and 28.8% S10: are added 1378 grams 0! caustic soda containing ‘76% NazO. 15 The solution is then evaporated until the total weight has been reduced to 5310 grams. This ’ solution is then allowed to cool to any convenient temperature below 53° C. 250 grams of crystal-1 line NazSiOa.5I-Iz0 together with 25 grams of 20 crystalline NazSiOa?HzO are then stirred in. The mixture is then ground on the two primary rolls oi’ an ink grinding roll mill for about one minute. ‘.25 ‘The third roll is then moved into place and the mass discharged onto the knii'e of the machine. The mass- will be white and opaque in color and will solidify immediately upon cooling. ' In all of the foregoing examples it will be noted as arecommonly used as a breakfast cereal, ex cept, of course, that these ?akes are white. This flaked product or any ground or comminuted form into which the‘ crystallized mass may be converted by suitable mechanical means .will re main dry, stable and free-flowing in storage. One way in which to determine the degree of transition into crystal‘ form which may result when practicing the foregoing process is to resort to the heat of solution test. It is a fact well known to physical chemists that soluble sub stances, when dissolved in water, either give oil or absorb heat, and the quantity of heat thus in volved is referred to as “heat of solution” and is expressed in calories per gram molecule. Thus, 15 for example, when one gramv molecule of MgSO4.7HzO is dissolved in 400 gram molecules of water, the system "will absorb 3800 gram calories. On the other hand, one gram molecule of MgSO4.H2O will give off 13,300 gram calories 20 and one gram molecule of MgSOr will give off ' 20,280 gram calories. - A similar relationship exists between the heats of solution for the various hydrates of the alkali metal silicates, and with particular reference to 25 sodium metasilicate, the values indicated in the following table have been obtained by dissolving, that I have described the use 0! a roll type ink on the one hand, 10 (grams of the crystallized ma grinding mill for the purpose of grinding the seeded solution. I wish it to be distinctly under stood, however, that it is not essential to the spirit and scope of the invention that a machine terial‘in 150 grams of water, and on the‘other hand, 10 grams of the uncrystallized supercooled 30 liquid in 150 grams of water. - of this type is necessary, as other grinding or ’ subdividing machines such as paint mills, colloid I Temperature change when Ill) grams of material are dissolved in 150 grams of water 35 mills or dlsintegrators may very well be em Crystals ployed for accomplishing the same purpose. In Liquid iact other expedients may be adopted, within the scope oi’ this invention, for causing the necessarily NilgSlOLQHjO _________________ _l —3. 48 i0. 02 —0. 55 ill. 02 thorough and intimate subdivision and distribu NmSiO1.8H10 _________________ __ —3. 10 N8:SlOl.6HIO. -_ —2. 25 i0. 02 i0. 02 —0. 53 —0. l5 5:0. 02 :i;0. 02 NmSlO;.5H:O _________________ _ _ =l;0. 02 +0. 14 i0. 02 40 tion of the seed. The factor which is important is to greatly multiply the foci of crystallization by comminuting or subdividing the seed, as by the grinding operation described. . Insofar as my present knowledge is concerned, it would seem that the action involved is a dis tribution of the seed, together with su?icient multiplication of the loci of crystallization of such nature as will serve to bring substantially all portions of the liquid into intimate contact with a focus oi’ crystallization, and this in a reasonably short space of time. The grinding em ployed in my invention operates to break up, sub divide or comminute the seed and/or the crystals as they are formed so that the whole mass crystal limintothedesiredhydrateinsuchawayasto substantially preclude, in the end product, the ?raence of supercooled or uncrystallized mother quor. ' -- l. 85 35 40 If one examines the table above he will noticev that in the case of NazSiO3.9H2O the uncrystal llzed solution lowers the temperature by 0.55° 0., whereas the crystallized material lowers the tem 45 perature by 3.48° C. A similar relationship exists in the case of each material. It will thus be seen that if a mixture ofv crystals and uncrystallized solution of the same chemical composition are used in this experiment a value will be obtained 50 which is less than that given by the uncontami nated crystals. From the values thus obtained it is possible to make a rough calculation of the amount ,of crystalline material in the sample taken. For example: Should the sample taken give a temperature lowering of 2.95, the amount or the crystallized material can be expressed as - The uniform dispersal or distribution of the crystals or crystal fragments may be likened to the distribution of a pigment in a vehicle to form paint. _ In any event the‘ distribution should be - extremely thorough ‘and the number of nuclei (2.95-—.55)100 =81.8% 3.48— .55 60 In the several examples given above heats of solution tests of the character just described in dicated that the degree of crystallization was should be multiplied to a _very great extent in - upwards of 90% in every instance and generally 65 ranged between 93.5% and 95%. order to obtain the best results. ‘ , I I have discovered that the desired result can be brought about by adding seed crystals or the de sired hydrate to the uncrystallized solution at room temperature and grinding and dispersing .70 this seed in the solution on an ink grinding roll mill or other grinding device. Where a roll type grinding mill is employed, such as‘ the ink grinding mill mentioned in the examples, it is possible to produce'an end product 7: of ?aky character very similar to corn ?akes such vI also wish to point out that in connection with all of the foregoing examples involving the speci?c grinding operation described, consider able latitude is permissible in the grinding time. For example,.I have conducted a series of tests 70 in which the grinding time was varied from 10 seconds to 5 minutes and the heat of solution test showed that crystallization was substan tially the same throughout the entire range. The criterion, therefore, is the nature of the end 76 51, 2,116,423 product. Intimacy of seed distribution should ‘tion, ?nely grinding the resultingv mixture of vcrystals and solution while simultaneously dis- v be sufficient to ensure a conversion into crystal persing the crystals rapidly and uniformly line form which will result in a dry, stable, free ?owing end product andyas indicated above”, I, throughout said mixture while said mixture is prefer to ‘operate in a range which will yield a still in‘ a liquid condition in such manner as to product which is crystallized substantially 90% produce a resulting crystallized product substan tially free from supercooled‘ liquid and capable of being comminuted to a dry, stable, free-Howe or more. . _ It will be seen, therefore,.that I, ‘have provided a method for producing crystalline hydrates of s U) the alkali metal ‘silicates and compositions con ing powder. ‘ 2. The method er claim 1 wherein crystalliza 10 taining the same in which it is unnecessary to ~ tion is initiated by seeding with a quantity of give any particular consideration to the tempera sodium metasilicate pentahydrate crystals. , 3. In the production of a composition of mat stability and‘character of the end product are ter containing a crystalline hydrate of an alkali metal silicate,.the method which includes prep 15 15 determined by suitable control of the seeding step as herein described. The extremely thorough and‘ aration of a solution which corresponds substan T-intimate manner of seeding the solution ‘which tially to the composition desired, cooling the so lution to any convenient temperature below the I have described will yield an end product char melting point of the crystallinehydrate, initiat acterized by substantially complete transforma ing crystallization thereof, ?nely grinding the 20 tion into crystal form. Furthermore, my im resulting mixture of crystals and solution while proved process may be used to produce the var f ture at which crystallization takes place. The ious alkali metal silicate crystal hydrates in sub- > simultaneously dispersing the crystals rapidly and stantially pure form, ‘i. e.,‘ uncontaminated with other hydrates. In other words, the end product may be characterized by the predominance of a single hydrate, which fact, in cooperation with the substantially complete crystallization which uniformly throughout said mixture ‘while, said mixture is still in a liquid condition in such man nerv as to produce a resulting crystallized prod 25 uct substantially free from supercooled liquid and capable of being comminuted to a dry, stabl ' takes place, is largely responsible for‘ the dry, free-flowing powder. 4. The method of claim 3‘wherein crystalliza stable, free-flowing qualities which are so vital 30 to a satisfactory practical and commercial‘ tion. is initiated by seeding with a quantity of 30 the crystalline hydrate desired. _ article. . 5. The method of making crystalline hydrates From the foregoing examples it will‘ also be seen that the transition from liquid to crystal form takes place in a much shorter interval of 35 time than has been possible heretofore. This fact lends itself particularly well to application of the invention to continuous manufacturing of alkali metal silicates which includes prepar ing a solution substantially corresponding to‘ the composition of a predetermined hydrate, cool‘ 35 ing the solution to any convenient temperature below the melting point of the said hydrate, ini- I tiating crystallization, ?nely grinding the result processes, the economic advantages of which are ' . ing mixture of crystals and solution while simule very material. taneously dispersing the crystals rapidly and 40 I should also like to point out that when . uniformly throughout said mixture while said the crystals vhave been comminuted; thus estab lishing the rapid rate of transition, the mass mixture is still in a liquid condition in such man ner as to produce a resulting crystallized product may be allowed ,to solidify as a ?lm which will substantially free from supercooled liquid and produce an end product in the form of ?akes, capable of being comminuted to a dry, stable, 45 45 or it may be mechanically atomized to yield a powder directly without grinding or it may be free-?owing powder. 6. The method of claim 5 wherein crystalliza; ' extruded through suitable apertures to yield ver tion is initiated by seeding with a quantity of micular particles. In short, the process may be adapted to produce a ?nished product in any the hydrate desired. [The method of making a definite hydrate 50' 50 one of a great variety of physical shapes adapted of sodium metasilicate which includes prepar tov commercial requirements and all of which are ing a solution approximately corresponding to characterized by, the properties of free-?owing the composition of the desired hydrate, initiating and stability. This has not heretofore been pos crystallization, ?nely grinding the resulting mix sible and results in another advantage, 1. e., 55 with my process the ?nished article can be pro duced in particles of predetermined shape and size.‘ .In practice the advantages of the invention ture of ' crystals and solution while simultaneous ly dispersing the crystals rapidly and uniformly 55. throughout said mixture while said mixture is still in a liquid condition in such manner as to produce a resulting crystallized product substan may be realized even in instances where other tially free from supercooled liquid and capable 60 60 materials may be added for the purpose of modi of being comminuted to a dry, stable, free-?ow fying the behavior of the crystals sought. By. ing powder. . ~ way of example, for detergent or other purposes, 8. The method of claim 'I wherein crystal materials such as starch, rosin, mineral or vege table oils, colloidal silicates and/or other agents lization is initiated by seeding with a quantity , 65 05 may be introduced where desired to modify the of the desired hydrate. 9. The method of making a de?nite‘ hydrate behavior of the crystal species without depart ing from the spirit and scope of the present ‘of sodium metasilicate which includes preparing _a solution approximately corresponding to the invention. I claimt- - 1. In the production of ‘sodium metasilicate pentahydrate', themethod which includes pre paring a solution of the approximate. composie tion of the said hydrate, cooling the solution to any convenient temperature below the melting 75 point of the said hydrate, initiating crystalliza compositionof the desired hydrate, cooling the solution to any convenient temperature below the melting point of the said hydrate, initiat ing crystallization, ?nely grinding the resulting mixture of crystals and solution while simultane ously dispersing the crystals rapidly and uniform ly throughout said mixture while said mixture is 75 ' 6 - 2,116,498 still in a liquid condition in such manner as to produce a resulting crystallized product sub stantially tree from supercooled liquid and ca pable of being comminuted to a dry, stable, tree? ?owing powder. 10. The method of claim 9 wherein crystallisa‘ tion is initiated by seeding with a quantity or the desired hydrate. 11. The method of making a de?nite hydrate 10 01' sodium metasilicate which'includes prepar ing a solution approximately corresponding to the composition of the desired hydrate, initiating crystallization and grinding the mass to subdi vide the-crystals in such manner as to distribute 15 fool of crystallization so intimately and rapidly as to result in a dispersal of the order of the distribution of a pigment in a vehicle to form paint, whereby the resulting product is at least 90 per cent crystallized. 20 I 12. The method of claim 11 wherein crystal lization is initiated by seeding with a quantity of the desired hydrate. 13. The method of preparing a ‘mixture oi’ crystalline trisodium phosphate and crystalline 25 sodium metasilicate which consists in preparing a liquid mixture calculated to satisfy the water requirements in the proportions of the two ma- , terials as desired in the ?nished product, cooling the solution to any convenient temperature below 30 the melting point of the crystalline sodium meta silicate, initiating crystallization, ?nely grinding the resulting mixture of crystals and solution I while simultaneously dispersing the crystals rap ‘as idly and uniformly throughout said mixture while said mixture is still in a liquid condition in such manneras to produce a resulting crystallized product substantially free from supercooled liq uid and capable of being comminuted to a dry. stable, free-?owing powder. 40 14. The method of claim 13 wherein crystal lization is initiated by seeding with a mixture of crystalline trisodium phosphate and crystal line sodium metasilicate. 4 15. The method of' preparing a mixture of sodi-' 45 um carbonate and sodium metasilicate pentahy drate which consists in preparing a solution of sodium metasilicate pentahydrate, adding sodi um carbonate in the desired proportiorninitiat ing crystallization, ?nely grinding the-resulting mixture 01' crystals and solution while siimiltane ously dispersing the crystals rapidly and-uni i'ormly throughout said mixture while said mix ture is still in a liquid condition in such manner as to produce a resulting crystallized product substantially free from supercooled liquid and capable of being comminuted' to a dry, stable, tree-?owing powder. 5 16. The method of claim 15 wherein crystal lizationis initiated by seeding with crystals of sodium metasilicate pentahydrate. - 1'1, In“ the production of crystalline composi tions of matter containing a crystalline hydrate 10 of an alkali‘ metal silicate and another compatible alkali'metal compound, the process which com prises preparing aliquid mixture having a com position substantially corresponding to that of 15 the desired ?nished product, cooling the liquid mixture to a point below ‘the melting point of the desired crystalline alkali metal silicate, ini tiating crystallization, ?nely grinding the mix ture of crystals and solution while simultane 20 ously dispersing the crystals rapidly and uni iormly throughout the liquid mixture while said mixture is still in a liquid condition in such manner as to produce a resulting crystallized product substantially free irom supercooled liq 25 non-caking, tree-?owing powder. uid and capable of being comminuted to a dry, 18. The method of claim 1'7 wherein crystalliza tion is initiated by the introduction of seed crys tals into the liquid mixture. ' 19. As a new composition of matter, granules of interlocking crystals of an alkali metal sili cate hydrate and sodium carbonate in a dry non 30. caking, free-?owing state, said crystals being substantially free from supercooled metastable 35 liquid and being substantially incapable of me chanical segregation, the alkali metal silicate in said composition being at least 90 per cent crys tallized and having substantially no tendency to agglomerate into solid masses. 40 20. As a new composition of matter, granules ‘ oi’ interlocking crystals of an alkali metal sili cute-hydrate and Na:PO4.I2HzO in a dry, non caking, free-?owing state, said crystals being substantially free from supercooled metastable 45 liquid and being substantially incapable of me chanical segregation, the composition as a whole being at least 90 per cent crystallized and hav ing substantially no tendency to agglomerate into solid masses. - ' 60 LBAKIR. .