US1436228A - Process of separating mixtures of salts - Google Patents

Description

H. P. BASSETT.

` PROCESS 0F SEPARATING MIXTURES 0F SALTS.

APPLICATION FILED AIR I4. 192i.,

Patented Nov. '21, 1922.,

Patented Nov. 2li, i922.

HARRY P. BASSETT, OF CYNTHIANA, KENTUCKY.

PROCESS OF SEPARATING MIXTURES 0F SALTS.

Application filed April 14, 1921.

To all wlmi/i. it may conce-rn:

Be it known that l, HARRY l. Bassi-rrr, a citizen ot' the linited States, residing-at C vnthiana. in the county of Harrison and State of Kentucky, have invented certain new and useful Improvements in lrocesses of Separating Mixtures of Salts. of which the following is a specification.

This invention relates to a process of separating a mixture of two 0r more salts in solid or crystalline form.

l have discovered that a mixture of two or inoie salts in solid or crystalline form can be separated by washing the mixture with a solution .of a salt containing the predominating acid ion or the predominating alkali ion in the mixture of salts, combined with an ion of the opposite cliaractei other than the ion with which it-is combined in the sait in the mixture in which it occurs.

The predominating acid and alkali ions in the salts in the mixture are determined as follows: Letting N represent the number of iinivalent molecules, i. e., molecules composed of univalent ions, as for example, NaCl. in which the ion is present, and V the valencyv of the ion. the redominating acid ion will be the acid ion in the mixture whose NXV exceeds the NXV of the other acid ion present, or if more than two acid ions are present. whose NXV exceeds the collective or combined NXV of the other acid ions in the mixture of salts, and the predominating alkali ion will be the alkali ion whose NXV exceeds the NXV of the other alkali ion present in the salt, or if there are more than two alkali ions present` whose NXV exceeds the collective or combined NXV of the other alkali ion's contained in such salts.

In this determination, a dibasic molecule,

such as (`aS(),. is to be considered as the equivalent of two univalent molecules and a trvalent molecule such as FeCla, as the equivalent of three univalent molecules and so on.

I have discovered that if a mixture of two solid or crystalline salts is washed with a wash liquor made up or composed of'a solution of the predominating acid ion or the predominating alkali ion `in the mixture combined with an ion of the opposite character, other than the ion with which it is combined in the salt in the mixture in which it occurs, the salt in the mixture whose NXV, i. e., the sum of the NXV Serial No. 461,366.

of its ions, is 'less than that of the other salt, will be removed or washed out, or if more than two salts are present one of which predominates to the extent that its N XV is greater than the collective or combined I\. V of the other orminor salts in the mixture. all of the minor salts will be removed and the predominating salt will remain, and that if there be added to a mixture ot' two or more salts, a suflicient quantity of a minor salt to make it the predominating salt., such salt in the practice of my process will remain and the other salt or salts including the salt which was formerly the predominating salt, will be washed out and removed so that by making such addition` the particular salt in mixture which it is desired to have remain'in the washing tank can be retained irrespective of. which is the predominating salt in the original mixture, and the other salt or salts washed out.

The practical application of my process will be understood from the following examples:

Ea'ample No. L n a mixture of solid or crystalline potassium chlorid and sodium sulfate, present in the ap roximate proportions ot 3KC1 to 1Na2S 4, chlorine is the predominating acid ion and this I employ combined with the alkali ion sodium, which, it will be noted, is a different alkali ion from that with which it is combined inthe salt in which it occurs in the mixture. The use of solium chlorid, b reason of its cheapness, is particularly advantageous.

Other solutions of salts of either of the two predominating ions present in the mixture combined with an lon of the opposite character other than the ion with which it is combined in the salt in which it occurs in the mixture, might be used, the selection being ordinarily determined by the availability or cheapness of the salts adapted for use in the wash liquor.

In treating 1000 pounds of this mixture to be separated, I preferablyemplo 160 to 320 pounds of sodium chlorid in t e wash liquor. Y

The sodium chlorid is referabl though not necessarily, employedpat a boi ing'temperature, in a solution substantially saturated at the temperature employed and the washing operation continued until the Na. ,S0, is substantially completely Washed out.

If, in the treatment of the two salts referred to, the quantity of NazS()4 be increased so that the salts are present in the mixture in approximately the proportion of lKCl to 1Na2SO sodium, which is one of the ions combined in the salt in solution in the wash liquor, ybecomes the predominating alkili lion and washing with the NaCl solution vwill result in KCl being washed out and the NazSO4l remaining in the washing tank. From this, it will be apparent that a minor ion may be made the predominatin ion b increasing the proportion of the sa t'in w ich it is contained and that if neither or none of the acid or alkali v ions predominates in the mixture, an acid and an alkali ion maybe made to predominate so that the salts in the mixture can be separated by my process, by increasing the quantity of the salt in which such acld or alkali ion is present whereby the salt selected to be left in the washing tank will remain and the other will be washed out.

E :temple N o. In separating a mixture of potassium chlorid, sodium sulfate and sodium carbonate in the approximate rochlorine is the predominating acid ion, and its NXV is greater than the combined NXV of the other acid ions present; consequently in the treatment of the mixture with a substantially saturated solution of sodium chlorid both the NazSO4 and NaZCOs will be washed out. f

In the treatment of 1000 pounds of this mixture, I preferably employ from 80 to 160 pounds of sodium chlorid in my wash liquor and conduct the operation under the conditions described in Example'v No. l, except that in this case I may advantageously employ the wash liquor at 33 C. which is the temperature of maximum solubility of both sodium sulfate and sodium carbonate.

In the practice of my process, the wash liquor is ordinarily preferably applied while heated to at or near 1ts boiling point and the temperature of such liquor should be maintained substantially at its initial temperature throughout the washing operation. If either sodium sulfate or sodium carbonate is to be removed by the wash liquor, I prefer to conduct, the operation at or about 33O C.

The wash liquor ordinarily consists of the salt selected for use in a solution which is concentrated to at or near the point of saturation at the temperature at which the washing operation is conducted and such temperature should not be materially altered during the operation as such alteration in temperature if considerable, would cause the solution to fall materially below the point of `saturation or cause a portion of salt therein to precipitate out.

It sometimes happens in the application 4oi my process to the separation of a mixture of more than two salts, as for example where two salts are present having the acid 0r alkali ion in common, and the other salt or other salts is or are predominated thereby, that only the minor salt or salts, and in many cases a single minor salt, will be removed by the useI of the selected wash liquor. In such case, the operation, is repeated, the remaining solid or crystalline salts being again treated as described using an appropriate wash liquor in each separation, and the operation successively carried out until only a single salt remains. In this wa by the use of my rocess, the salts washe out of a mixture o salts frequently can be successively removed andv recovered separately from the other salts in the mixture.

In the treatment of a mixture of two or more saltsit sometimes happens that neither or none of the acid or alkali ions predominates. In such case, theJ ions of one of the salts, i. e., the one which is to remain in the washing tank, are made to predominate either by the addition to the mixture of more of such salt whereby the NXV of its ions will be increased to the required degree or by the use of a wash liquor which by its reaction upon one or more of the salts to be separated, will suilicientl increase the NXV of the ions of the salt w ich is to remain in the washing tank or sufficiently decrease the NXV'of the ions of one or more of the salts to be removed, so that the NXV of the ions of the salt which is to remain in the washing tank after the operation, will predominate in the mixture.

The proportion by weight of the salt ir; the wash liquor to that of the salt or salts to be separated may be varied within such wide limits that the quantity of salt to be used therein can be determined by considerations of economy and convenience of operation. Letting M represent the molecular weight of the individual salts in the mixture to be separated, it has appeared from my experiments that the proportion by weight ofthe salt in the wash liquor to that of the salts to be separated may be `varied from approximately zero if the amount of the salt to be removed is very small, upward to an amount such that the NXVXMof the salt y.in the wash liquor plus theN V M of the salt or salts to be removed shall not equal or exceed the NXVXM of the predominating salt, i. e., the one to be left in the washing tank. This, however, as a practical matter, is considered to be relatively unimportant as considerations of economy and convenience of operation will indicate the use of a quantity of salt in the wash liquor well within these limits.

I ordinarily employ a substantially saturated solution of the selected salt as my wash liquor, but this is not necessary, providing the mixture of salts to be separated contains sium salt is in addition to the principal salts therein, a. quantity of the salt which is in solution in the wash liquor. In such case, only such quantity of the selected salt need be dissolved in the wash liquor that it will become saturated by dissolving the like salt present in the salts under treatment.v For example, if the mixture contains potassium chlorid, sodium sulfate and a limited amount of sodium chlorid, I dissolve only such an amount of sodium chlorid in the wash liquor that the sodium chlorid in the mixture will be dissolved and the wash liquor thereby rendered saturated. The potassium chlorid and sodium sulfate will then be separated by the action of the saturated solution of sodium chlorid as explained in Example No. l.

I ordinarily employ as a wash liquor in my process, a solution of a single salt but I have found it advantageous in some cases to make use of a salt solutionV containing the particular salt which I desire to use and which also contains a solution of some other salt having no disturbing effect upon the separation. In such case, for reasons of economy, I make use of such solution without first removing the second salt.

It will be apparent that two or more salts in solution may be separated by my process by first separating the salts from the liquid i'n which they are dissolved by evaporation or otherwise and the salts in the resulting solid or crystalline mass treated as described herein.

It will be apparent froml the foregoing description and examples, that the wash liquor will in all cases, be a solution of a salt other than the salt which it ,is desired to remove from the salt mixture.

While my process is perfectly adapted for use in separa-ting all salts in solid or crystalline form, I have found that a particularly valuable application of it is to the separation of the constituents, as for example, the potassium content, of potassium containing liquors, such as brine from certain lakes in Nebraska, southern California, Utah, and elsewhere, the leachings of Wood or kelp ash, vinnasse cinders or flue dust or any other natural orar-artificial liquor in which a potasresent.

In 'the pre erred practice of my process as applied' to the treatment of brine containing, for example, 7 per cent by weight of solids consisting approximately of 35 per cent potassium chlorid, 35 and 30 per cent sodium carbonate, the proportions being by weight, I first evaporate the solution to the point of saturation in one evaporating tank, transfer the solution v while hot to a second evaporating tank where it is further evaporated and a portion of the salts in solution, preferably about onethird of the-total salts in solution, crystallized out.

r cent sodium sulfate SES The mixture in this precipitate consists principally of sodium sulfate and sodium carbonate with a relatively small percentage of potassium chlorid. In a series of experiments on brines from lakes near Antioch, Nebraska, this mixture in each instance was found to contain about per cent sodium sulfate, 14 per cent sodium carbonate and 16 per cent potassium chlorid, the proportions being by weight.

The remaining solution is then transferred to a third tankwhere the hot solution is cooled, preferably to about the temperature of the atmosphere, (although it may be refrigerated to any desired low temperature), thereby causing the precipitationof a portion of the remaining salts, ordinarily about one-third of such remaining salts. The last mentioned precipitate consists principally of potassium chlorid. In a series of experiments, above referred to, this precipitate was found to consist of about 60 per cent potassium chlorid, the balance being sodium sulf fate and sodium carbonate in about the proportions of 29 per cent of sodium sulfate and 11 per cent of sodium carbonate, the proportions being by Weight.

The remaining solution is then returned to the first tank and the operation is repeated in the manner described, additionalbrine being ordinarily added thereto. Whatever salts are being separated and whatever wash liquors are used, I prefer to add the Wash liquor after its final use to the liquid under treatment whereby the salts, or the more valuable of the salts, in the used wash liquor may be recovered.

The solid or crystalline salts crystallized out of the solution in the second tank are then treated to separate the potassium chlorid from the remainin salts. This I preferably accomplish by t e use of a wash liquor containing a substantially saturated solution of thepredominating alkali ion in the mixture, sodium, combined with an ion of the opposite character, i. e., an acid ion, other than the ion with which it is combined in the salt or salts in the mixture in which it occurs, and, for reasons of economy, prefer to em loy a substantially saturated solution,

of so ium chlorid as the wash liquor.

The wash liquor is preferably applied at approximately boiling temperature and the washing continued until allor practically all of the potassium chlorid is washed out. The-wash liquor after the washing operation will consist principally of sodium chlorid solution containing a minor portion of potassium chlorid dissolved therein. The potaium content of this Wash liquor may if desired, be recovered by adding such used' wash liquor to the liquor under treatment in the first evaporating tank, but the practice hereinafter set forth is ordinarily followed.

The solid or crystalline salts in the third tank are then treated to remove the sodium sulfate and Sodium carbonate. In the mixture of salts in the third tank, chlorine is the predominating acid ion and in the wash liquor, this is employed combined with sodium, which is an alkali i011 different from the ion with which chlorine is associated in the salt in the mixture in which it occurs. Inasmuch as the-MNXV of the chlorine ion in the mixture is'greater than the combined NXV of other acid ions in such mixture, the use of sodium chlorid as theV ..-W'ash liquor will result in washing outboth of the sodium salts from the mixture, leaving the potassium chlorid. In this operation, the sodium chlorid is employed in a substantially saturated solution, preferably at a temperature of 33o C., and the operation is continued until the potassium chlorid is Washed free or practically free from sodium sulfate and sodium carbonate.

, I may advantageously employ the wash liquor which has been used in Washing the salts in the second tank to wash the salts in the third tank and in practice, this I prefer to do. Whe-re this is done, the salts in the third tank, after the treatment described, may be and preferably are, washed with a saturated solutionof pure sodium chlorid "and by such treatment the potassium chlorid may be practically freed from the sodium sulfate and sodium carbonate.'

In the practical application of my process, as applied to the treatment of potassium containing brine of the character referred to, I may advantageously employ the apparatus shown in elevation, with arts in section, in the accompanying drawing. In the drawing, the numeral 1 designates a pipe connected with a source of supply (not shown) of the brine to be treated. This pipe which is provided with a valve 2, serves to conduct the liquor t'o the first eva-porating tank 3. Tank 3 is provided with a water jacket 4, adapted to receive superheated steam'or other heating agent to effect the evaporation of liquor in the tank. From the bottom-of the tank 3, a valve controlled pipe 5 leads to the second evaporating tank 6, a pump 7 being inserted in the' line to effect the transfer of liquor from tank 3 to tank.

Tank 6 is provided with a water jacket 7', adapted to receive superheated steam or v other heating agent by mea-ns of which the liquor in the tank 6 is evaporated.

The-bottom of the tank 6 is connected by means of valve controlled pipes 8 and 9 with salt boxes 10 and 11, as shown, the valves in such pipes permitting of either of such salt boxes being separately used in connection with the tank 6. The salt boxes 10 and 11 are supplied with doors 12 and 13 through wfhich the salts crystallized or precipitated out of the liquor in tank 6 may be removed from time to time. From the bottom of the tank 6, pipe 14 leads to the bottom of tank 3 and is provided with a valve controlled branch pipe 15, also connectingr it with the bottom of a cooling or refrigerating tank l6. Interposed in the pipe 14 between tank 6 and the branch 15, is a pump 17 designed to transfer liquor from tank 6 to either tank 16 or tank 3. and interposed in such pipe between the branch 15 and the tank 3 is a pump 18, adapted to effect the transfer of liquor from tank 16 to tank 3.

Tank 16 is provided with a. jacket 19, adapted to receive a cooling or refrigerating agent such as Water at atmospheric temperature or below by means otl which the contents of tank 16 is cooled. From the bottom of tank 16. valve controlled pipes 20 and 21 lead to salt boxes 22 and 23, the valves in the pipes 2O and 21 permitting either salt box 22 or 23 to be separately connected with the tank 16 so that either or both salt boxes may be used in connection therewith.

The salt boxes 22 and 23 are provided with doors 24 and 25, through which the contents of the boxes may be removed from time to time.

A pipe line 26 is connected by valve controlled pipes 27, 28, 29 and 30, with the bottom of salt, boxes 10, 11, 22 and 23, and by means of valve controlled pipes 31, 32, 33, and 34, with the top of salt boxes 10, 11, 22, and 23, as shown. The pipe line 26 leads to apump 35, and is provided with a valve 36 located adjacent the pump as shown. The pump 35 is connected by means of a pipe 37 with the bottom of a tank 38. This pipe isp provided with a valve 38, adjacent the pump 35, as shown. Pipes 26 and 37 are connected by meansof valve controlled by-pass pipes 4() and 41, by-pass pipe 40 leading from pipe 26 betweenY branch pipe 34 and valve 36 and connecting with pipe 37 between the pump 35 and the valve 39 and the valve 39 and bypass 41 leading from the pipe 26 betweenthe pump 35 and the valve 36 and connecting with the pila 37 between the tank 38 and the valve 39. y this arrangement, the pum '35 may be used to pump liquor in either d1- rection as will be readily understood. Pipe 37 is provided with a branch pipe 42 which extends over tanks 38 and 43, and is provided with two valve controlled branches 44 and 45, whereby liquor can be pumped through the pipe 42 into either of the tanks 38 or 43. A second branch pipe 46 leads from the pipe A37 and is connected with the bottom of tank 43 by a valve controlled connection 47. Pipe 37 is provided with a valve 48, located between the tank 38 and the branch pipes 42 and 46.

The tanks 38 and 43 are storage tanks for the Wash liquor used in separating the solid or crystalline salts in salt boxes 10, 11, 22 and 23 and are provided `with jackets 49 and 50 adapted to receive superheated steam or other heating agent, 'whereby the contents of these tanks can be maintained at a desired elevated temperature.

Connected with the pipe 37 below the branch pipes 42 and 46 is a valved olf-take pipe 51 leading into a third storage tank 52. This tank is connected at its bottom with Y the brine intake pipe 1 by means of a pipe line 53, providedl with a valve 54, adjacent the tank 52 and a valve 55, adjacent the intake pipe 1. A pump 56 connected in this line of pipe serves to transfer liquor from tank 52 to the intake pipe 1, through which it is run into the first evaporating tank 3.

In the use of the apparatus illustrated, the brine to be treated is conducted from the source of supply to the first evaporating tank 3. Here it is evaporated until it is substantially saturated. It is then pumped by means of the pump 7 to the second evaporating tank 6, where it is heated until a substantial part, ordinarily about one-third by Weight of the salts in solution, is crystallized out. If the valves in pipes 8 and 9 are both open, the salt crystallized out will settle into the salt boxes 10 and 11 or if the valve in one of the pipes 8 or 9 is closed, the salt' will settle through the pipe which is open into the salt box connected therewith. It is advantageous to provide each of the tanks 6 and 16 with two salt boxes so that one of them may be cut o' from the tank in connection with which it is used and such salt box emptied Without interfering with the continuous operation of the process.

The liquor remaining in tank 6 is then pumped into tank 16 where it is refrigerated and an amount of salt equivalent to about one-third by Weight of t e remaining salts in the liquor is precipita ed, the salts settling into either salt box 22 or 23er both, as desired.

The substantially saturated salt solution to be used as the wash liquor for the salts in salt boxes 10 and 11 is placed in tank 38 and heated therein to the desired temperature, preferably to its boiling point, and is then pumped by means of pump 35 through pipes 26 and 31 or 26 and 32 into the top of salt boxes 10 and 11, oryif the valves in pipes 31 and 32 are open into both salt boxes, and the crystals therein subjected to the action of a washliquor. Then by opening the valves in the connecting pipes 27 and 28, the Wash liquor can be withdrawn by means of the pump 35 and returned, and the operation repeated until the desired degree of washing is completed. When the salts in salt boxes 10 and 11 have been sufficiently washed, the resultin wash liquor is pumped l into tank 43 where its temperature is maintained b means of the heating agent in the jacket 5 The washed salts in the salt boxes 10 and 11 will consist of sodium sulfate and sodium carbonate, substantially free from potassium chlorid and these salts may be withdrawn for use or sale.

The salts in the salt boxes 22 and 23, connected with the third or refrigerating tank 16 is then washed and I may employ as the wash liquor a freshly prepared solution of sodium chlorid butv prefer to employ the solution already used in washing the contents of salt boxes I10 and 11, the small amount of potassium chlorid therein not interfering with the operation of the second washing process. In this operation, the wash liquor in tank 43 is pumped by means of the pump 35 through pipe 26 and pipes 33 or 34 into the salt boxes 22 or 23, or if the valves in pipes 33 and 34 are open into both salt boxes and the Washing operation carried out in the manner-described until the sodium sulfate and sodium carbonate in the salt mixture are substantially wholly removed therefrom. The Wash liquor, after the final washing, is pumped by means of pump 35 through pipes 26, 37 and 51 into the storage tank 52, Where it may be advantageously returned by means of pump 56 through pipe 53, into the intake pipe 1 and from there tothe irst evaporating tank 3.

If it should be found in any case that the mixture of solid or crystalline salts in salt boxes 10 and 11 or in salt boxes 22 and 23 contains no predominating ion, the proportion of a salt in the mixture may be increased so that it will be made to predominate and the separation elected as described. From the foregoing description, it will be understood that an important feature of my process consists in separating' salts from a solution thereof, successively in a plurality of operations, the resulting salts being obtained in a plurality of batches in which the proportions of the salts are such that different salts predominate in different batches l whereby the predominating salt in each instance can be separated as described from the other salt.or salts and will remain .in solid form in the vessel in which the washing operation is conducted.

It will be understood by .those skilled in the art that, in the practice of my process, the salts to be separated should preferably be in a more or less finely divided condition to facilitate solutionof the salts to be removed.

This application is in part, a continuation of my application Serial No. 274.085, filed January 30, 1919, allowed May 21, 1919, renewed January 10, 1920, Serial No. 387,990, for process ofseparating mixtures of salts, and in part a continuation of my application Serial No. 274,087, filed January 30, 1919, for process of treating potassium containing liquors.

" l-`While Ihave illustrated my process by reference to certain specific salt mixtures, it is to be understood that my process is not limited to the separation of these salts or salts of a generally similar character thereto, but is of general application and that the details of procedure as herein before set forth may be widely varied as by conducting the washing operation under superatmospheric pressure which is contemplated as within my invention though ordinarily unnecessarily expensive, repeating a washing operation as many times as required to obtain a desired degree of purity ofthe major salt and the like, all without departing from the principle or spirit of my invention or the scope of the subjoined claims.

Having thus described my invention, I

claim:

1. The herein described process of separating salts which consists in subjectingr a mixture of salts in solid or crystalline form to the action of a substantially saturated solution of a salt other than a saltto be removed, containing one of the predominating ions present in such mixture combined with an ion of the opposite character other than the ion with which it is combined in the salt in which it occurs in such mixture and separating the liquid from the solid portion of the resulting mass.

2. The herein described process of separating salts which consists in washing a mixture of salts in solid or crystalline form with a wash liquor comprising a substantially saturated solution of a salt other than a salt to be removed, containing one of the predominating ions present in such mixture combined with an ion of the opposite character other than the ion with which it is combined in the salt in which it occurs in such mixture whereby the salt in which such predominating ion is present will be separated from the other salt or salts in the mixture.

3. The herein described process of separating salts which consists in washing a mixture of salts in solid or crystalline form with a wash liquor comprising a hot substantially saturated solution of a salt other than a salt to be removed, containing one of the predominating ions present in such mixture combined with an ion of the opposite character other than the ion with which it is combined in the salt in which it occurs in such mixture whereby the salt in which such predominating ion is present will be separated from the other salt or salts inthe mixture. v

4. The herein described process of separating a mixture of solid or crystalline salts wherein there is no predominating ion, which consists in increasing the quant-ity of one of the salts in the mixture until its ions predominate over the ions of the other salt or salts in; the mixture and washing such mixture with a substantially saturated solution of a salt other than a salt to be removed,

containing one of the predominating ions present in such mixture combined with an ion of the opposite character other than the ion with wlnch it is combined in the salt in which it occurs in such mixture whereby the salt in which such predominating ion is present will be separated from the other salt or salts in the mixture.

The herein described process of separating a mixture ot' salts in solid or crystalline form in which such salts are presentl in a predominati'ng and in a minor proportion therein which consists in washing such mixture with 'a substantially saturated solution of a salt other' than a salt to be removed, comprising an ion present in the predominating salt in such mixture combined with anion of the opposite character other than the ion with which it is combined in such predominating salt. and separating the liquid from the solid portion of the mass.

6. The herein described process of separating a plurality of salts in solution` one of which salts is of superior value, which consists in separating` from the liquid in which such salts are dissolved a mixture of salts in which mixture the salt of superior value is present in a minorfproportion, then separating from the liquid from which the first mixture of salts was separated, a mixture of salts in which mixture the salt of superior value is present in a major proportion, and subjecting each separated mixture of salts to the action of a wash liquor containing a substantially saturated solution of a salt other than a salt to be removed, comprising,r a predominating ion present in the mixture combined with the ion of the opposite character other than the ion with which' it is combined in the salt in the mixture in which it occurs.

7. The herein described process of separating a potassium salt from a sodium salt occurring in a solution thereof which consists in first separating from the liquid in which such salts are dissolved, a mixture of salts in which mixture the potassium salt is present in a minor proportion, then separating from the liquid from which the first mixture of salts was separated, a mixture of salts in which theppotassium salt is present in a major -proportion and subjecting each of the two mixtures of salts to the action of a wash liquor comprising a substantially saturated solution of a salt, other than a salt to be removed, comprising a predominating ion present in such mixture combined with an ion of the opposite character other than the ion with which it is combined in the salt in the mixture in which it occurs.

8. The herein described rocess of separating potassium chlorid om the sodium` sa ts otherthan sodium chlorid, the salts being in solution, which consists in first separating from the liquid in which the salts 1 ,aaazae are dissolved, a mixture of salts in which the roportion of potassium chlorid is relative v small as compared with the sodium salts. then separating from the liquid from which the first mixture of salts was separated. a mixture of salts of which the major portion consists of potassium chlorid and subjecting each mixture to the action of a wash liquor com )rising a substantially saturated solution vo sodium chlorid.

9. The herein described process of separating otassium chlorid from sodium salts other t an sodium chlorid, thev salts being in solution, which consists in first separating from the liquid in which the salts are dissolved, a mixture of salts in which the proportion of potassium chlorid is relatively small as compared with the 'sodium salts, then separating from the liquid from which the first mixture of salts was separated, a mixture of salts of which the major portion consists of potassium chlorid, subjecting the mixture first separated to the action of a substantially saturated solution of sodium chlorid and subjecting the second mixture to the action of the solution used in treating the first mixture.

10. The herein describedV process of separating potassium chlorid from sodium salts other than sodium chlorid, the salts being in solution, which consists in first separating from the liquid in which the salts are disso ved, a mixture of salts in which the proportion of potassium chlorid is relatively small as compared with the sodium salts, then separating from the liquid from which the first mixture of salts was separated, a mixture of salts of which the major portion consists of potassium chlorid, subjecting the mixture' first separated to the action of a substantially saturated solution of sodium chlorid, subjecting the second mixture to the act-ion of the so'- lution used in treating the first mixture, adding the wash liquor to the solution under treatment, and repeating the operation.-

11. The herein described process of separating potassium chlorid from sodium sulfate and sodium carbonate, the salts being in solution, which consists in first separating by evaporation a mixture of salts in which mixture the proportion of potassium chlorid is relatively small as compared with the sodium salts, then separating byV refrigeration of the solution from which the first mixture. was separated, a mixture of salts in which the major portion consists of potassium chlorid, subjecting the mixture first separated to the action of a substantially saturated solution of sodiumc-hlorid and subjecting the second mixture tothe action of the solution used in treating the first mixture.

12. The herein described process of separating potassium chlorid from sodium sulfate and sodium carbonate, the salts being in'solution, which consists in first separating by evaporation a mixture of salts in which mixture the proportion of potassium chlorid is relatively small as compared with the sodium salts, then separating by refrigeration of the solution from which the first mixture was separated, a mixture of salts in which the major portion consists of potassium chlorid, subjecting the mixturefirst separated to the action of a substantially saturated solution of sodium chlorid, subjecting the second mixture to the action of the solution used in treating the first mixture, adding the Wash liquor to the solution under treatment and repeating the operation.

y 18. The herein described process of separating a plurality of salts in solution, which consists 1n separating a mixture of dissolved salts from the liquid in which the salts are dissolved and subject-ing the mixture to the action of a wash liquor containing a substantially saturated solution of a salt other than a salt to be removed, comprising an ion present in the predominating salt in the mixture combined with an ion of the opposite character other than the ion with which itis combined in such predominating salt.

14. The'herein described process of separating a plurality of salts in solution, which consists in separating a mixture of dissolved salts from the liquid in which the salts are dissolved and subjecting the mixture to the action of a wash liquor containing a hot, substantially saturated solution of a salt other than a salt to be removed, comprising an ion present in the predominating salt in the mixture combined with an ion of the opposite character other than the ion with which it is combined in such predominatf ing salt.

In testimony whereof I affix m si ature.

" P. B S

HARRY TT.

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