1,990?751 3 tion containirig . 350 gallons of' watei, and 89 poutds of sodium@aluminate containing 58 per cent @ A1203 is mixed' thoroughly in. an agitation tank tvith a solution fbrrved by diluting@53 galIons of 43 degree Baum6 water glass (analysis corresponding to Na2O.3SiO2) with 300 gahons ,of water. Agitation or stirring is continued until reaction is coinplete and a fluid pulp containing precipitate suspended in mother liquor is pro-, 10 duced. The resulting pulp is of about the consistency of cream and it is pumped to a solar drying fleld provided with large concrete drying fl6ors or platforms havi-ng peripheral retaining walls. The pulp is placed on the drying.floors to 15 a depth of three or four inches and subjected to the heat of the sun's rays uiitil a brittle cake capable of decrepitating is produced. The pulp spreads evenly and a dried cake of uniform thickness is @ obtained. 20 During the early stages of the drying operation the p@ecipitate settles and is protected from the direct action of the sun's ra-ys by a layer of clear niother liquor. While the water contained in the c6vering liquid is evaporating, the precip2.,-, itate settles to form a compact mass or layer which has the appearance of a wet mass or layer of a crystalline substance such as salt or sugar. The pulp, when produced, contains more than twenty-five pounds of water per pound of solids 30 and it off ers little or no resistance to the passage of a knife blade until it has dried to an incipient cake containing about ten pounds 6r less of water per pound of solids. It, therefore, retains its homogeneity during drying better than any 35 previously known product. The cake, if undisturbed during drying, shrinks and cracks to form smaller cakes of different sizes and shapes before drying is completed. This may result in uneven drying which 4,0@ will make it difficult to have all of the material reach the most desirable decrepitating condition at the sanie time. In order to, overcome the tendency for the material to break into cakes of irregular shapbs and sizes, we find it advisable 45 to cut the mass into small cakes before drying has been completed and before cracking due to shrinkage has progressed to any considerable extent. A series of parallel vertical cuts may be made to produce a number of parallel strips 50 which will break into smaller cakes of rather uniform size in shrinking. Small cakes having no dimension greater than several inches will pass tbrough the final drying period without breaking further to any considerable extent and 55 drying wiR be uniform. in order to better explain our processes and without limiting the scope of our invention, the following hypothesis, based on accepted colloid theory, is advanced. If a sol is allowed to set 60 into a gel, the solution will be bound in a rigid structure made up of cells knowri as micellae. Authorities differ on whether the micellae ronsist of a closed honeycomb structure or whether the cell walls form a sponge-like structure 65 through which the intermicellar liquid can flow or drain. Probably different colloids vary. Some of the large single cells in wood are almost certainly closed. In the case of the zeolite gels, which resemble silica gels, the evidence is not 70 so clear. The cellular structure must be there, both in the complete jelly and in the gelatinous precipitate. A precipitate forms either from a very dilute mixture or from an ordinary mixture which is stirred during reaction. This feathery 75 precipitate entangles a great deal of mother liquor just as wet feathers can retain an immense amount of water. If a jelly is broken mechanically, many of the cell walls are ruptured and the mass reduces to a gelatinous precipitate. It seems reasonable to suppose that a @5 precipitee suspended in raother liquor would allow passage of the mother liquor to the surface for drying mgre easily than does a coinplete jelly whose cell-walls would tend to interfere with free passage of water. Tnis illustrati@s one 10 of the advantages of drying a gela inous precipitate in comparison with drying a complete jelly. We have noted another great advantage in drying a mush of precipitate. The jelly structure of a complete jelly is rigid ' as comb honey 15 is rigid, and in drying a mass containing 96% water to a cake containing 5OVo water, a shririkage to less than 10% of the o-riginal vblume occurs. Unequal drying causes the complete jelly to be put under strain and it tears apart 20 into unequally sized pieces during this shrinkage. The sr@ialler cakes,then overdry and do not decrepitate to the desired cor.,lmercial sizes while the large cakes under-dry and also will not decrepitate efficiently. i-he same is true of a fil- @5@ ter cake of precipitate as formed by heretofore customary processes, for ihe reason tha;t the cake is not eqlially compacted when Olaced in the &ier. In the case 6f a pi:ecipitate mush drying, the shrinkage cracks do not appear s 30, early. For the mixture given in the. 6xample above, a complete jelly begins to show shrir@kage cracks when the. average moisture of the drying jelly reaches about 11.5 to 12 pounds of water per pound of anhydrous solids. The saine mixture if reduced to a precipitate mush wfll not sho w shrinkage cracks uncil the moisture has bee n reduced to about 7 to 8 pounds of water p--T pound of anhydrous solids. By cutting the mus h with knives, as mentioned above, urliform- 40 ity of drying can be furthered. Also, if rapid dry' mg takes place only at one end of a cake, moi sture travels through the cake as through a wick and equahzes the differenece. As the mas s sets into a ha-rdem'ng mud, a profound re- 45 arra ngement takes place and the final dried cak e is similar in appearance toi the dried cakes pro duced by all other wet methods. s rearra ngement toward the end of drying is not so profound as a recrystallization but much 50 mor e profound than the hardening of drying mud . The cell walls of the gelatinous structure are probably collapsed. We claim,- 1. The method of preparing an artificial zeo- 55 lite which comprises mixing solutions of sodium alu minate and sodium silicate under conditions of thorough agitation to form a precipitate in fluid suspension, and subjecting the resulting pro duct to a.low temperature ' drying operation. 60 2. The method of preparing an artificial zeolite which comprises mixing solutions of sodium alu minate and sodium silicate under conditions of thorough agitation to form a precipitate in susp ension in mother liquor, and subjecting the 65 resu lting product to a solar drying operation. 3. The method of preparing an artificial zeolite which comprises mixilig solutions of reage nts under such conditions as to form a complet e jelly, breaking the jelly to produce a fluid 70 pulp , and subjecting the resulting pulp to a lowtem perature drying operation. 4. The method of preparing an artificial zeolite which comprises forming a complete jelly by mixing solutions of sodium aluminate and

4 1,990,751 sodium silicate, breaking the jelly to pr6duce a fluid pulp, and subjecting the resulting pulp to a low-temperature drying operation. 5. The method of preparing an artificial zeolite which comprises forming a pulp in which a gelatinous precipitate is suspended in mother liquor, and subjecting the entire pulp containing the mother liquor and the precipitate to a drying operation until a brittle cake is obtained. 10 @6. The method of preparing an artificial zeolite which comprises mixing solutions of sodium aluminate and sodium silicate under conditions of thorough agitation to form a precipitate in suspension in mother liquor, ai@dsubjecting the 15 entire pulp containing the mother liquor and the precipitate to a drying operation until a brittle cake is obtained. 7. The method of preparing an artificial zeolite which comprises mixing solutions of re20 agents under such conditions as to form a complete jelly, breakin- the jelly to produce a fluid pulp, and drying @he resulting pulp at a low temperatufe to obtain a brittle cake. 2r) 8. The method o@' preparing an artificial zeolite which comprises forming a completle jelly by mixing solutions 6f sodiuri alumip-ate and sodium silicate, breakin.- the jelly to produce a fluid pulp, and drying the resulting plilp at a low temperature to obtain a brittle cake. 30@ 9. The method of preparing an artificial zeolite which comprises i,-qixing solutions of sodium aluminate and sodium silicate underconditions of thorough agitation to form a precipitate in suspension in mother liquor, pumpinr,, the re35 sulting pulp to a suitable dryiiig receptacle, and drying the entire pulp at. a low temperature until a brittle cake is obtained. 10. The method of preparing an artificial zeolite which comprises mixing solutions of re40 agents under conditions of thorough agitation to orevent the forniation of A, jelly and to form a precipitate in fluid suspension, and subjecting the entire pulp containing the mother liquor and the precipitate to a low temperature drying operation. 5 11. The method of preparing an artificial zeolite which comprises mixing two or more reagents under such conditions that a gelatinous precipitate in fluid suspension is produced, and subjecting the entire resulting pulp containing 10 the mother liquor and the precipitate to a drying operation at a temperature not lower than about 70' F. and not higher than about 100' F. 12. The melhod of preparing an artificial zeolite which comprises mixing solutions of sodium 1,5 aluminate and sodium silicate under such conditiot-is that a gelatinous precipitate in fluid suspension is produced, and subjecting the entire resulting pulp containing the mother liquor and the precipitate to a drying operation at a temperature not lower than about 701 P. and not higher than about 100' P. 13. The method of preparing an artiflcial zeolite which conprises mixing two or more reagerts under such conditions that a gelatinous 25 precipitate in fluid suspension is produced, and subjectir-g the entire resulting pulp contairiin.the niother liquor and the precipitate to a dryinu operation at a temperature not higher than about 120' F. 30 14. The method of preparing an artificial zeolite which comprises mixing solutions of sodium aluminate and sodium silicate under such cond,'@t4@ons that a gelatinous precipitate in fluid suspension is produced, and subjecting the entire resultin.- pulp containing the mother liquor aiid the precipitate to a drying operation at a ten-perature not higher than about 120' F. OLIVER C. RALSTON. KENNETI-I MICHAEL BAUM. 40

Patented Feb. 12 1935 1 9 9 9 0 9 - 7 5 1 @ UNITED: STAT@E@S PATENT OFF@ICE 1,990,751 PR,,ODUCTION OF BASE EXCELALNGE AND SIMILAR MATERIALS Oliver C. Ralston, Clarkdale, and Kenneth IVL-chael Baum, Yuma, Ariz.; Emmett J. Oulligan, adnunistrator @of said Kenn@ih M. Bauini, deceased assignor of the entire right of said Batiro- to Arizona Minerals CorjDoration, Yuma, Ariz., a corporation of Arizona, No Drawing. : Application September 26, 1930, @Seiial No. 484,706 14 Claims. (Cl. 23-113) Tb-is invention i-elates to the p@-oduction of base exchange, adsorbent and cataiytic riiateri,qls and has for an object the pr6vision of @an @mproved process for piepa-ritig such materials. e par e on M6r ticularl@, the 'inv nti contemplates the provision of an iniproved wet @ r-,ieth6d of prepblring artificial zeolites. The invention further conteinpl@tes the productign of improl,,E@d ze6lite products. lo According to the heretofore cuslomary practices, zeolites hav6 been ireiared by fusion processes aiid wet processes. The fusi6n processes commonly used involve the @-neltin-- of suitable ingredients to produce fl-uid homo eiieous, I 9 glass-like w-@sses whi-ch I are subsequentl@ hardened and crushed or broken to. piodiice small graiiules and washed t6 remove free alkali sa,lts. The wet processes commonly ii I sed involve the procluction of gelatinous pi:eciijitates in liquid 20 susl:i6nsio@ or the pi,oduction 6f complete jellies 4y mixing solutioils of suitable rc-agents. The complete jellies are rigid structares embodying all of the s6lvents @Mployed and aU of the reaction products. 25 The fluid products c6ntaining the gel@tinous precipitates a-re usually filtered and the D-reci,3itates washed to rem6ve a portion of the free a'lkali salts f@ rmed by the -reacti6n resulting from the mixing of the solutions. The washed 30 proclu@ts are dried to form hard, @brittle cakes which are further washed and granulated to ]@roduce , particles of desired sizes. The complet e jellies pr6duced are sometimes dried withoilt washing to remove free alkali salts in an eff6rt 35 to produce material in the form of brittle cakes in Nvhich the gel stru6tures are retained. The cakes s6 prodiiced are v7 ashed and granulated to provid6 parti6les 6f - s'uitable sizes a'nd substantially identical wi'h -the granules produced 40 from dried precipitate cake. The glass-like substances -,jroduced by @the fusion, processes, and the dried cake ryisteria@i prodlice I d by the wet l@rocesses all ]@ave the p@opeity of @decrei)itatiiig into granui6s when I sub45 ject,ed to the action of water. In@ the case of prbducts of wet processes, i the chaiacter df the decrepitati6n appears to depend to some ey@'Gent upon the water content of the &ied cake. The material will not decrepitate un til drying@ has 00 proceeded to a certain extent, aiid, when &ying has been carried on for too long a period, decrepitati6n may resiilt in the production' of undesirable am6unts of very fine partlicles@ It is therefote d@sirable. to avoid o and io obt in @in eyenly @d@ied:produ is diffi cult to obtain an evenly dried product by the hereto fore 6ustoiiiiiry proces@e@ because the precip itates bnd jellies shrink and braelt in drying to produce c@kes of diffe@ent sizes which proce ed 'o the final dry condition at different 5 rates. Whi le no definite explanation 6f the property of decrepitati6n is known, it is gqiierally believe d'.that it may be at least @ pattly attributed to hyd@ation or swellin of the dried iriaterials 10 9 r(Dsl @lting f@6in.in,.mersion iii water and/or dis@oiution oi- the soluble alkali salts c6ntained in t@ie -dry materials. It is believed that anothek fact6 @ of gieat importance in producing decrepiis the @air pressure caused by the rush of 15 wate r into the sub-microscopic capillaries. Cons6qu ently, the size@ shaiie and number of these capiIlari-es are of great im-portance, and these featu res Eire no doiibt modified by the physical cha @racter 6f ti@e dr@ing mass and b@ the metliod 20 of d:ryillg. Th e prodess of our inventioi-i involves control of conditions under which the prodiicts @ resultiiig fi-om thE@ iiiixin,& 6f solutions of r,eagents are forin ed arid/or @ontrol of c ' onditions under which 25 ihe l@ioduct.1,@ are dri6d. The dry products of the heret6fore @iist6mary processes, whi@e capa@ -6 of gianulatin r @l g or dOc epitating to some extent upon tre4i@ent with wpter, are of such naiu're s the@t gi@anulation cannot be controlled sat- 30 isfact orily. in.@ome in.stances decrepitation proceed s@to such @n extent that large amounts of very fine @@rticies 'are produced. In other instanc es @ieer.epitatio3@ proce.eds only slightly, with tiie,,i esult that large amounts of relatively large 35 p-qrticie@, too lar@e for ordinary commercial purposes, are pr6duced, and it is necessary to subject the large particles thus produced to crushing or grinding operations to pr,oduc@ gr,anuies of suitable sizes. The natur6 of the d-ry products and 40 the 6hard.eter of the-available crushing o-r grinding m@'chinery a're' sucl@ that it is difficult to@ a,@oid the pr,oductioli of undesirable amounts of hne @particieswhen crushing or grindiug operations are necessary., @45 We'have discovered that a dry cake or material which granulates readily to produce higialy 4esirabl- quantities of su-itably sized particles may I 66 produ@ed by controlling the conditions under w-hich 6or4plete jellies and gelatinous pre50 cipitates a,re produced and/or dxied. Wd )@.ave f6iina that dry product@ -whi6h de6rel3itate ve:ty satisfactorily may be produced by drying com@ plete jpllies and gelatinous precipitates at 16w 1 50 tem@er,,@tiares. l@Tyirig m.@iy be, continiied unti

2 1,990)751- immersion in water of a sample of the material being dried indicates that a satisfactory decrepitating stage has been reached. In carrying out the processes of our invention we conduct the &ying operation witliin the temperature range of 321 F. to 120, F. and preferably between 70, F. and 1001 F. We have found that -improved results may be obtained when the heat is applied to the upper surface of the ma10 terial being dried. This may be accomplished by placing heating elements above the material bei-ng dried or by passing a current of heated air ove,- the surface of the material in suitable.containers. We have used solar drying with great 15 success, the products obtained being superior to those obtained in carrying out processes involv.ing the use of other heating means. In forming zeol',.tes for commercial purposes by first producing complete jellies, we may form the 20 jellies b3r mixing the usual reagents in suitable proportions with only sufficient stirring or agitation to cause thorough mixing-. After the complete jellies have been formed, the drying operat4.on may be commenced, and the drying may be 25 continued at- a low tempe-rature until tests indicate that it @s capable of decrepitating satisfactorily. The drying of complete jellies under the conditions and a@t temperatures within the range de30 scribed above results in the production of improved products, but we have found that better and more uniform products may be obtained bY forming and drying gelatinous precipitates unde-r controlled conditions. We, therefore, prefer to 35 produce and treat gelatinous precipitates as distinguished from complete jellies. The gelatinous precipitates may be ptoduced by first forming a, complete jelly and then breaking the jelly by means of an agitator or similar device to form a 40 fluid pulp, or by mixing reagents with water under conditions of thorough agitation to prevent the formation of a complete jelly. A complete preferred process of our invention involves the niixing of suitable reagents in suita45 ble proportions and with sufficient stirring or agitation to prevent the formation of a complete jelly, followed by gradual elimination of excess water by drying alone or by decantation and drying. The mixing operation should be so con50 ducted that the components of the resulting product wiR separate upon standing undisturbed to form a layer of precipitate covered by a layer of supernatant mother liquor. We prefer to dry the precipitate without any preliminary wash55 ing, but, if desired, washing of the precipitate after partial or complete decantation of supernatant liquid, br washing after partial drying and before the decrepitation stage has been reached, may be conducted. 6o We prefer to conduct the mixing operation in agitator tanks or other receptacles which are particularly suitable for that purpose and transfer the resulting product to separate pans or receptacles for drying. We have found it to be ado5 vantageous to produce a relatively thin or highly fluid product of the mixing operation in order to permit transfer by means of pumps from the mixing receptacle to the drying pan or receptacle. @ Proper fluidity nia@ be obtained by using 70 suitably dilute solution@ of reagents or by using concentrated solutions of reagents and adding water after the mixing operation has been completed. The product of the mixing operation is 75 pumped to the drying pans where separation of the components commences immediately. Upon standing, the precipitate settles to form a compact mass covered by mother liquor. Heat may be applied at any time after the material has been placed in the drying pans. When a satis- 5 factory separation of precipitate and mother liquor has been accomplished, the supernatant mother liquor may be with&awn, but we have found it to be advantageous to permit at least a portion of the mother liquor to remain in con- 10 tact with the precipitate during the early stages of the drying operation. The preferred process of our invention is particularly suitable for use in conjuncton with solar evaporation. The fluid product of the mix- 15 ing operation can be pumped readily long distances and we may, therefore, use large and extensive drying pans. Such drying apparatus may be of very simple construction, consisting essentially of large platforms having level sur- 20 faces covered with layers of impervious material and provided with suitable side walls for confining @he fluid. The drying platforms may be provided with roofs or not, as desired. Furthermore, since the heat for drying is available 25 without egst, no penalty is attached to the use i of sufftcient water to g,ve the desired ' Iuidity or to permitting the mother liquor to remai-n in contact v@,,ith the precipitate during the dryin.- operation. The quantity of water employed and 31) the procedare V.Lth respect to decantation will be governed to some extent at least by weather conditions and available drying pan area. The nature of our preferred process is such that rnany economies which cannot be achieved by the heretofore customary processes may be observed. Thus, for example, we have eliminated the filtering and washing operations which have been eniployed in the heretofore customary processes dealing with the production and drying 40 of gelatinous precipitates. Furthermore, the retention of the mother liquor in the precipitate mush permits pumping of the material directly from the mixing apparatus or from a storage receptacle to the drying pans or solar evaporati-n,- 45 fi-elds. The installotion and operating costs of pumps are tr-Lfling in comparison with those of filters, conveyors and their auxiliaries. The final products of the processes of our invention have higher base exchange capacities 50 than the products of the heretofore customary processes. The better commercial products of the heretofore customary processes could not be produced consistently with more than twelve thousand grains of CaCO3 baz-e exchange capacity per cub4ic foot of particles between 10 and 20 mesh in size. Our products have capacities expressed in grains of CaCO3 per cubic foot of 10 to 20 mesh particles, of over fourteen thousand and frequently of over sixteen thousand. 6( In carrying out the prefelted process of our invention, we prefer to form separate solutions of the different reagents and mix the solutions under such conditions that the production of a complete jelly is prevented. In forming sodium 65 aluminum silicates, we prefer to employ solutions of sodium silicate and sodium aluminate in such proportions that a reaction product containing five to six molecules Of SiO2 tO each complete molecule of the resulting compound is pro- i'O duced. Such a product will probably consist of a mixture of compounds having the formulae Na2O.Al2O3.5SiO2 and Na2O.Al2O36SiO2. The following example will serve to illustrate the preferred process of our invention. A solu- 75