CA1334721C - Method for the production of potassium sulfate - Google Patents
Method for the production of potassium sulfateInfo
- Publication number
- CA1334721C CA1334721C CA 560414 CA560414A CA1334721C CA 1334721 C CA1334721 C CA 1334721C CA 560414 CA560414 CA 560414 CA 560414 A CA560414 A CA 560414A CA 1334721 C CA1334721 C CA 1334721C
- Authority
- CA
- Canada
- Prior art keywords
- sulfate
- potassium
- fact
- solution
- k2so4
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 229910052939 potassium sulfate Inorganic materials 0.000 title claims abstract description 64
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 title claims abstract description 62
- 238000000034 method Methods 0.000 title claims abstract description 46
- 235000011151 potassium sulphates Nutrition 0.000 title claims abstract description 29
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims abstract description 95
- 239000001103 potassium chloride Substances 0.000 claims abstract description 47
- 235000011164 potassium chloride Nutrition 0.000 claims abstract description 47
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims abstract description 37
- 150000003839 salts Chemical class 0.000 claims abstract description 18
- 150000001450 anions Chemical class 0.000 claims abstract description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims abstract description 6
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 claims description 21
- 238000005342 ion exchange Methods 0.000 claims description 21
- 239000011347 resin Substances 0.000 claims description 15
- 229920005989 resin Polymers 0.000 claims description 15
- 238000006243 chemical reaction Methods 0.000 claims description 12
- 229910052943 magnesium sulfate Inorganic materials 0.000 claims description 12
- 235000019341 magnesium sulphate Nutrition 0.000 claims description 10
- 239000000047 product Substances 0.000 claims description 9
- 229920006395 saturated elastomer Polymers 0.000 claims description 7
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims description 6
- 239000007832 Na2SO4 Substances 0.000 claims description 5
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 5
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 5
- 235000011152 sodium sulphate Nutrition 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims description 5
- 229910052602 gypsum Inorganic materials 0.000 claims description 3
- 239000010440 gypsum Substances 0.000 claims description 3
- GMLLYEDWRJDBIT-UHFFFAOYSA-J magnesium;dipotassium;disulfate Chemical compound [Mg+2].[K+].[K+].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O GMLLYEDWRJDBIT-UHFFFAOYSA-J 0.000 claims description 3
- 239000002244 precipitate Substances 0.000 claims description 3
- 150000003467 sulfuric acid derivatives Chemical class 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 2
- 239000000725 suspension Substances 0.000 claims 2
- WZISDKTXHMETKG-UHFFFAOYSA-H dimagnesium;dipotassium;trisulfate Chemical compound [Mg+2].[Mg+2].[K+].[K+].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O WZISDKTXHMETKG-UHFFFAOYSA-H 0.000 claims 1
- KKXBBXAHWYSVBG-UHFFFAOYSA-L dipotassium sulfate hydrochloride Chemical compound Cl.[K+].[K+].[O-]S([O-])(=O)=O KKXBBXAHWYSVBG-UHFFFAOYSA-L 0.000 claims 1
- 238000001556 precipitation Methods 0.000 claims 1
- 239000000243 solution Substances 0.000 description 63
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 10
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 8
- 229910052700 potassium Inorganic materials 0.000 description 8
- 239000011591 potassium Substances 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- 238000005349 anion exchange Methods 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 5
- 239000011780 sodium chloride Substances 0.000 description 5
- 239000012452 mother liquor Substances 0.000 description 4
- 238000011068 loading method Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 229910001414 potassium ion Inorganic materials 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 239000012266 salt solution Substances 0.000 description 2
- 238000009738 saturating Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 229910020324 KCl—K2SO4 Inorganic materials 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- 238000006887 Ullmann reaction Methods 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- ZLCCLBKPLLUIJC-UHFFFAOYSA-L disodium tetrasulfane-1,4-diide Chemical compound [Na+].[Na+].[S-]SS[S-] ZLCCLBKPLLUIJC-UHFFFAOYSA-L 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 229910052928 kieserite Inorganic materials 0.000 description 1
- 229910001629 magnesium chloride Inorganic materials 0.000 description 1
- 239000010446 mirabilite Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 1
- 230000003134 recirculating effect Effects 0.000 description 1
- 239000012047 saturated solution Substances 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- RSIJVJUOQBWMIM-UHFFFAOYSA-L sodium sulfate decahydrate Chemical compound O.O.O.O.O.O.O.O.O.O.[Na+].[Na+].[O-]S([O-])(=O)=O RSIJVJUOQBWMIM-UHFFFAOYSA-L 0.000 description 1
- WBHQBSYUUJJSRZ-UHFFFAOYSA-N sodium;sulfuric acid Chemical compound [H+].[H+].[Na+].[O-]S([O-])(=O)=O WBHQBSYUUJJSRZ-UHFFFAOYSA-N 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Saccharide Compounds (AREA)
- Preparation Of Compounds By Using Micro-Organisms (AREA)
- Processing Of Solid Wastes (AREA)
- Treatment Of Water By Ion Exchange (AREA)
Abstract
A description is given of a method for the production of potassium sulfate in which a potassium chloride solution is first reacted with an anion exchanger loaded with sulfate ions, as a result of which sulfate ions are desorbed and chloride ions are adsorbed and the resulting solution containing potassium chloride and potassium sulfate is reacted with a sulfatic double salt and potassium sulfate is formed.
Description
-1- 1 33472~
The state of the art (cf. "Ullmanns Encyklopadle der technischen Chemie" [Ullmann's Encyclopedia of Industrial Chemistry], 4~h edition, 1977, vol. 13, p. 480) includes methods for the production of potassium sulfate in which a sulfatic double salt, containing MgSO4 or Na2SO4 in addition to K2SO4, is reacted with a potassium chloride solution at one stage in the process. This gives rise to the formation of a crystallizate of potassium sulfate. The following are double salts from which potassium sulfate is obtained in this manner in industrial processes:
- Leonite : K2SO4 . MgSO4 4H2O
- Schoenite : K2SO4 . MgSO4 ~ 6H2 - Langbeinite : K2SO4 . 2MgSO4 - Glaserite : 3K2SO4 Na2S4 The reaction takes place, for example, according to the following equation:
3K2SO4 . Na2SO4 + 2KCl c 4K2SO4 + 2NaCl.
In all cases involving the above-mentioned methods of producing potassium sulfate, solutions are formed which in addition to MgCl2 and NaCl also contain considerable quantities of KCl and also of sulfate ions. These solutions must either be discarded, which results in considerable losses of valuable materials, or they must be evaporated, thereby recovering salts containing potassium and sulfate. This requires a high input of heat energy and therefore is very costly.
Methods for obtaining potassium sulfate in anion exchange processes are known in which an exchanger is loaded with sulfate ions and these ions are then desorbed by reaction with a potassium chloride solution and replaced by chloride ions.
The state of the art (cf. "Ullmanns Encyklopadle der technischen Chemie" [Ullmann's Encyclopedia of Industrial Chemistry], 4~h edition, 1977, vol. 13, p. 480) includes methods for the production of potassium sulfate in which a sulfatic double salt, containing MgSO4 or Na2SO4 in addition to K2SO4, is reacted with a potassium chloride solution at one stage in the process. This gives rise to the formation of a crystallizate of potassium sulfate. The following are double salts from which potassium sulfate is obtained in this manner in industrial processes:
- Leonite : K2SO4 . MgSO4 4H2O
- Schoenite : K2SO4 . MgSO4 ~ 6H2 - Langbeinite : K2SO4 . 2MgSO4 - Glaserite : 3K2SO4 Na2S4 The reaction takes place, for example, according to the following equation:
3K2SO4 . Na2SO4 + 2KCl c 4K2SO4 + 2NaCl.
In all cases involving the above-mentioned methods of producing potassium sulfate, solutions are formed which in addition to MgCl2 and NaCl also contain considerable quantities of KCl and also of sulfate ions. These solutions must either be discarded, which results in considerable losses of valuable materials, or they must be evaporated, thereby recovering salts containing potassium and sulfate. This requires a high input of heat energy and therefore is very costly.
Methods for obtaining potassium sulfate in anion exchange processes are known in which an exchanger is loaded with sulfate ions and these ions are then desorbed by reaction with a potassium chloride solution and replaced by chloride ions.
According to German patent AE~ tion (~ (Offer~ ss~hrift) No.
33 31 416 of Superfos A/S, ~lhli~;he~ March 8, 1984, a Cl-lo~
exchanger is bmught into contact with a sll~nsi~n of gypsum (calcium sulfate) and loaded with sulfate ions. I~e sulfate ions are ~l~s~r~l using a 25% sL~ylh ~6Cl solution and cryst~ te of pot~sillm sulfate is precipitated out by saturating the solution with KCl.
According to German patent ~ ~tion No. P 36 07 641 of K~li und Salz AG, plhl;~hetl ne~rnhPr 4, 1986, anion e~c~hangers are loaded with sulfate ions by reacting them with MgSO4 solutions. The sulfate ions are desorbed from the resin by means of a saturated potassium chloride solution which at the same time is saturated with potassium sulfate. In this case, potassium sulfate crystallizes out during the exchange reaction.
According to European Patent Specif ication No . 0 ,199 ,104 of R. Phinney, published October 29, 1986, anion exchangers loaded with sulfate are reacted with an approximately 5096 solution of potassium chloride. The result is a potassium sulfate solution which still contains potassium chloride. ~rom this solution potassium sulfate is precipitated out by dissolving potassium chloride. The resulting approximately 5096 solution of potassium chloride, which is saturated with potassium sulfate, is again used to desorb sulfate ions from the ion exchanger.
These anion exchange processes have the advantage that they make extremely efficient use of the raw materials. In particular, a very high yield of potassium can be achieved. On the other hand, high investment and operating costs are incurred for a plant used for the production of K2SO4 according to the ion exchange process.
It has now been discovered that it is advantageously possible to combine an anion exchange process for the production of potassium sulfate with other potassium 6ulfate production methods in which sulfatic double salts are dec rsed with potassium chloride olutions in one rtage of the process, with potassium sulfate -_3_ 1 33472 1 crystallizing out. This method makes use of the highly efficient utilization of raw materials possible with the ion exchange process. At the same time, however, the process can be considerably simplified by the fact that procedural steps of both production processes can be jointly carried out, and also by the fact that complicated recycling of solutions is not needed for the ion exchange process.
The method according to the invention makes use of the fact that on the one hand in various processes for the production of K2S04 sulfatic double salts are reacted with a potassium chloride solution and the product potassium sulfate forms; but on the other hand, when an anion exchange is carried out with a potassium chloride solution, sulfate ions are desorbed from the exchanger which is loaded with sulfate ions, and this also produces potassium sulfate according to the equation R2S04 + 2KCl = 2RCl + K2S04.
The amount of potassium chloride solution used to desorb sulfate ions from the exchange resin is no more than the amount which is in any case needed for the reaction with the double salt, therefore a "sulfate mother liquor" forms only for the amount of K2S04 resulting from the reaction with the double salt. This liquor must either be directly disposed of or recycled for further processing, at the end of which some liquor still has to be disposed of and valuable materials are lost as a result. The valuable materials potassium and sulfate can only be recovered to any great extent by carrying out a very expensive evaporation process. The amount of K2S04 which is obtained via the ion exchange process on the other hand does not create any accumulation of "sulfate mother liquor" and thus avoids all the problems associated with the disposal or further use of such liquor. Thus, ion exchange offers an opportunity to increase the --4- 1 ~ ~4721 production of K2SO4 without having any consequences on the liquor economy of the process.
In one variant of the method, the sulfate-loaded exchanger is reacted with a concentrated solution of potassium chloride. This produces a solution depleted of KCl and saturated with K2SO4, together with solid K2SO4. Most of the dissolved K2SO4 is precipitated out by saturating the solution with KCl and a KCl solution is obtained of the kind required to decompose the double salt in the other production process. The solution can be saturated with KCl while the ion exchange is taking place by adding solid KCl to the KCl solution right at the start. As the double salt breaks down, the K2SO4 still remaining in the solution crystallizes out so that finally all the sulfate ions desorbed from the ion exchanger are obtained in the form of K2SO4-crystallizate in addition to the K2SO4 derived from the decomposition of the double salt.
In the variant described here, K2SO4 precipitates out during the exchange process. This requires a difficult procedural step to separate the KCl-K2SO4 solution together with the K2SO4 crystallizate from the resin. However, in another variant, the procedure can be greatly simplified while avoiding these difficulties. In this case a solution which is not saturated with KCl is used to desorb the sulfate; this solution can take up more K2SO4 than a saturated solution. The process is carried out advantageously at an elevated temperature of approximately 50 to 80C because - while the overall concentration of potassium ions stays the same - the ability of the solution to take up K2SO4 increases with temperature.
The solution coming from the exchanger and still undersaturated with K2SO4 is saturated with KCl, as described above, and used to decompose the double salt.
The potassium~sulfate which ac~, IAtes in the dec_ -sition ~tage of both processes is jointly further processed in the 601ids-liquids-separation and the drying phases of the production method.
One najor advantage of combining an anion exchange process for obtaining potassium sulfate with another potassium sulfate process is that the potassium chloride 601ution merely runs through the ion exchange process, as it were, and that as a result fresh RCl solution is constantly supplied to this process. This does away with complicated recycling of solutions of the kind raquined in the methods described in German patent application No. OS 33 31 416, p7hlich~ Mb$~h 8, lg84, and in Germ~n patent Arpl~~tion No. P 36 07 641, published rerPr~er 4, 1986.
The enrichment of impurities, 6uch as 60dium chloride in the recirculating ~Cl solution, is also avoided and it is possible to use a potassium chloride which is highly contaminated with NaCl, provided that this NaCl does not disrupt the process of breaking down the double salt. Since it is constantly necessary to prepare a new RCl solution, the thin solutions containing potassium salt which ac~, ~Ate in the ion exchange process may be used for this purpose and dilution effects can be compensated for in solutions used for building up or reducing concentrations. Practically no loss of potassium occurs. Nor is any 6ulfate lost in this part of the process. As a result, the half-cycle of desorption of sulfate ions from the resin can be carried out efficiently and simply.
When selecting the sources of sulfate for loading the exchanger with sulfate ions, preference i8 given to those which are also used in the methods combined with the ion exchange. The sources may, for example, be kieserite (MgS04 . H20), if leonite or 6choenite are formed as inte ~di~te products, or thenardite (Na2S04) or Glauber's salt (~a2S04 . 10~20) with glaserite forming as the intermediate product.
-Of course, the loading of the exchanger can also be carried out with natural waters containing sulfates in solution, as is the case for example in lakes containing Na2S04 and MgS04.
It is, however, fundamentally possible to use various sulfate sources, e.g. calcium sulfate (gypsum) for the ion exchange and Mg or Na sulfates in the procedure combined with the ion exchange.
The following examples provide further explanations of the method.
~7 1 334721 r !~ 1 .. " *
100 L of the weakly basic exchange resin Duolite A 374, loaded with Cl ions, was 85% loaded with sulfate ions in an exchange column filled with a solution containing 120 g MgSO4/L adjusted to pH 3.
Once the saliniferous solution had been displaced from the resin bed bymeans of water, the exchanger was transferred to a stirring vessel.
Once the water had been drained from the pore space the resin was reacted with 100 L of a RCl solution having a temperature of 55C and containing 362 g XCl/1.3 g K2SO4/L (Solution 1) and 17.7 kg RCl crystallizate, while stirring carefully. During the reaction sulfate ions were desorbed from the resin, the RCl solution took up R2SO4 until the saturation point was reached and further R2SO4 precipitated out as a crystallizate.
The R2SO4-saturated RCl solution which was formed (Solution la), the fine R2SO4 crystallizate and the unused RCl were separated from the resin by screening; the resin was then returned to the exchange column using Solution la. Next, the following solutions were added one after the other:
2) 30 L containing 240 g KCl/L
33 31 416 of Superfos A/S, ~lhli~;he~ March 8, 1984, a Cl-lo~
exchanger is bmught into contact with a sll~nsi~n of gypsum (calcium sulfate) and loaded with sulfate ions. I~e sulfate ions are ~l~s~r~l using a 25% sL~ylh ~6Cl solution and cryst~ te of pot~sillm sulfate is precipitated out by saturating the solution with KCl.
According to German patent ~ ~tion No. P 36 07 641 of K~li und Salz AG, plhl;~hetl ne~rnhPr 4, 1986, anion e~c~hangers are loaded with sulfate ions by reacting them with MgSO4 solutions. The sulfate ions are desorbed from the resin by means of a saturated potassium chloride solution which at the same time is saturated with potassium sulfate. In this case, potassium sulfate crystallizes out during the exchange reaction.
According to European Patent Specif ication No . 0 ,199 ,104 of R. Phinney, published October 29, 1986, anion exchangers loaded with sulfate are reacted with an approximately 5096 solution of potassium chloride. The result is a potassium sulfate solution which still contains potassium chloride. ~rom this solution potassium sulfate is precipitated out by dissolving potassium chloride. The resulting approximately 5096 solution of potassium chloride, which is saturated with potassium sulfate, is again used to desorb sulfate ions from the ion exchanger.
These anion exchange processes have the advantage that they make extremely efficient use of the raw materials. In particular, a very high yield of potassium can be achieved. On the other hand, high investment and operating costs are incurred for a plant used for the production of K2SO4 according to the ion exchange process.
It has now been discovered that it is advantageously possible to combine an anion exchange process for the production of potassium sulfate with other potassium 6ulfate production methods in which sulfatic double salts are dec rsed with potassium chloride olutions in one rtage of the process, with potassium sulfate -_3_ 1 33472 1 crystallizing out. This method makes use of the highly efficient utilization of raw materials possible with the ion exchange process. At the same time, however, the process can be considerably simplified by the fact that procedural steps of both production processes can be jointly carried out, and also by the fact that complicated recycling of solutions is not needed for the ion exchange process.
The method according to the invention makes use of the fact that on the one hand in various processes for the production of K2S04 sulfatic double salts are reacted with a potassium chloride solution and the product potassium sulfate forms; but on the other hand, when an anion exchange is carried out with a potassium chloride solution, sulfate ions are desorbed from the exchanger which is loaded with sulfate ions, and this also produces potassium sulfate according to the equation R2S04 + 2KCl = 2RCl + K2S04.
The amount of potassium chloride solution used to desorb sulfate ions from the exchange resin is no more than the amount which is in any case needed for the reaction with the double salt, therefore a "sulfate mother liquor" forms only for the amount of K2S04 resulting from the reaction with the double salt. This liquor must either be directly disposed of or recycled for further processing, at the end of which some liquor still has to be disposed of and valuable materials are lost as a result. The valuable materials potassium and sulfate can only be recovered to any great extent by carrying out a very expensive evaporation process. The amount of K2S04 which is obtained via the ion exchange process on the other hand does not create any accumulation of "sulfate mother liquor" and thus avoids all the problems associated with the disposal or further use of such liquor. Thus, ion exchange offers an opportunity to increase the --4- 1 ~ ~4721 production of K2SO4 without having any consequences on the liquor economy of the process.
In one variant of the method, the sulfate-loaded exchanger is reacted with a concentrated solution of potassium chloride. This produces a solution depleted of KCl and saturated with K2SO4, together with solid K2SO4. Most of the dissolved K2SO4 is precipitated out by saturating the solution with KCl and a KCl solution is obtained of the kind required to decompose the double salt in the other production process. The solution can be saturated with KCl while the ion exchange is taking place by adding solid KCl to the KCl solution right at the start. As the double salt breaks down, the K2SO4 still remaining in the solution crystallizes out so that finally all the sulfate ions desorbed from the ion exchanger are obtained in the form of K2SO4-crystallizate in addition to the K2SO4 derived from the decomposition of the double salt.
In the variant described here, K2SO4 precipitates out during the exchange process. This requires a difficult procedural step to separate the KCl-K2SO4 solution together with the K2SO4 crystallizate from the resin. However, in another variant, the procedure can be greatly simplified while avoiding these difficulties. In this case a solution which is not saturated with KCl is used to desorb the sulfate; this solution can take up more K2SO4 than a saturated solution. The process is carried out advantageously at an elevated temperature of approximately 50 to 80C because - while the overall concentration of potassium ions stays the same - the ability of the solution to take up K2SO4 increases with temperature.
The solution coming from the exchanger and still undersaturated with K2SO4 is saturated with KCl, as described above, and used to decompose the double salt.
The potassium~sulfate which ac~, IAtes in the dec_ -sition ~tage of both processes is jointly further processed in the 601ids-liquids-separation and the drying phases of the production method.
One najor advantage of combining an anion exchange process for obtaining potassium sulfate with another potassium sulfate process is that the potassium chloride 601ution merely runs through the ion exchange process, as it were, and that as a result fresh RCl solution is constantly supplied to this process. This does away with complicated recycling of solutions of the kind raquined in the methods described in German patent application No. OS 33 31 416, p7hlich~ Mb$~h 8, lg84, and in Germ~n patent Arpl~~tion No. P 36 07 641, published rerPr~er 4, 1986.
The enrichment of impurities, 6uch as 60dium chloride in the recirculating ~Cl solution, is also avoided and it is possible to use a potassium chloride which is highly contaminated with NaCl, provided that this NaCl does not disrupt the process of breaking down the double salt. Since it is constantly necessary to prepare a new RCl solution, the thin solutions containing potassium salt which ac~, ~Ate in the ion exchange process may be used for this purpose and dilution effects can be compensated for in solutions used for building up or reducing concentrations. Practically no loss of potassium occurs. Nor is any 6ulfate lost in this part of the process. As a result, the half-cycle of desorption of sulfate ions from the resin can be carried out efficiently and simply.
When selecting the sources of sulfate for loading the exchanger with sulfate ions, preference i8 given to those which are also used in the methods combined with the ion exchange. The sources may, for example, be kieserite (MgS04 . H20), if leonite or 6choenite are formed as inte ~di~te products, or thenardite (Na2S04) or Glauber's salt (~a2S04 . 10~20) with glaserite forming as the intermediate product.
-Of course, the loading of the exchanger can also be carried out with natural waters containing sulfates in solution, as is the case for example in lakes containing Na2S04 and MgS04.
It is, however, fundamentally possible to use various sulfate sources, e.g. calcium sulfate (gypsum) for the ion exchange and Mg or Na sulfates in the procedure combined with the ion exchange.
The following examples provide further explanations of the method.
~7 1 334721 r !~ 1 .. " *
100 L of the weakly basic exchange resin Duolite A 374, loaded with Cl ions, was 85% loaded with sulfate ions in an exchange column filled with a solution containing 120 g MgSO4/L adjusted to pH 3.
Once the saliniferous solution had been displaced from the resin bed bymeans of water, the exchanger was transferred to a stirring vessel.
Once the water had been drained from the pore space the resin was reacted with 100 L of a RCl solution having a temperature of 55C and containing 362 g XCl/1.3 g K2SO4/L (Solution 1) and 17.7 kg RCl crystallizate, while stirring carefully. During the reaction sulfate ions were desorbed from the resin, the RCl solution took up R2SO4 until the saturation point was reached and further R2SO4 precipitated out as a crystallizate.
The R2SO4-saturated RCl solution which was formed (Solution la), the fine R2SO4 crystallizate and the unused RCl were separated from the resin by screening; the resin was then returned to the exchange column using Solution la. Next, the following solutions were added one after the other:
2) 30 L containing 240 g KCl/L
3) 30 L containing 120 g RCl/L
4) 60 L water.
During the reaction and by using Solution 2 to displace saturated RCl/R2SO4 solution from the resin, a product fraction consisting of - 100 L solution containing 356 g RCl/L and 15 g R2SO4/L (Solution la) - 13.5 kg R2SO4 crystallizate and - 4.7 kg unused KCl was obtained.
After the product fraction, the following solutions were obtained as eluates:
* Trademark --8- 1 33472~
2a.) 30 L containing 246 g RCl/L and 6 g K2SO4/L, 3a.) 30 L containing 129 g KCl/L and 4 g R25O4/L, 4a.) 30 L containing 12 g KCl/L.
30 L of water remained in the exchange resin which was ready for the next loading with MgSO4 solution.
By dissolving 24.6 kg KCl, 100 L of KCl reaction solution (Solution 1) was prepared for the next exchange cycle from Solutions 2a.) to 3a.).
In addition, in each case 30 L of Solutions 2.) and 3.) were freshly prepared by dissolving 7.2 and 3.6 kg RCl respectively.
Since only traces of potassium ions remained in the exchanger, the potassium yield of the process was more than 99~.
The 100 L of product fraction (Solution 1a.) from the ion exchange process was then reacted with 64.5 kg schoenite (K2SO4 . MgSO4 . 6H2O).
The following were obtained:
- 115 L of "sulfate mother liquor" at a temperature of 39C and containing 215 g KCl/L, 87 g Mgcl2/L and 58 g MgSO4/L and - 61.2 kg K2SO4, of which 15.0 kg was from the ion exchange process.
Thus for one part of K2SO4 product obtained from the decomposition of schoenite, 0.32 parts of K2SO4 were obtained from the ion exchange.
r ~xample 2 100 L of weakly basic Kastel 102 A exchange resin loaded with Cl ions was 90% loaded with sulfate ions in an exchange column using a solution containing 40 g Na2SO4/L and 3 g NaCl/L which was adjusted to pH 4.
The salt solution was displaced from the resin bed by means of water.
Next, 170 L of solution at 50C containing 162 g KCl/L at 50C and 2 g R2SO4/L, followed by 90 L of water, were applied to the bed.
The following solutions were eluted:
1.) 17 L salt-free water, 2.) 30 L containing 2.5 g KCl/L and 2.9 g R2SO4/L, 3.) 183 L containing 83 g KCl/L and 76 g K254/L, 4.) 30 L containing 12 g RCl/L and 9 g K25O4/L-The low-salt solutions 2.) and 4.) were used to produce new KCl solution to use in the following exchange cycle. By dissolving 27.1 kg RCl in these solutions and water, 170 L of solution for charging into the exchange process was obtained.
The potassium yield was more than 99%.
The product solution 3.) of the ion exchange process contained 13.9 kg K25O4. This solution was reacted with 95.1 kg of a glaserite product having the composition Na2SO4 . 2.8K2SO4 and 56.3 kg KCl-crystallizate.
The reaction yielded the following:
- 203 L of a "sulfate mother liquor" having a temperature of 30C and containing 241 g KCl/L, 87 g NaCl/L and 25 g K2SO4/L and - 108.6 kg ~2SO4, of which 13.9 kg came from the ion exchange process.
Thus, for one part of K2SO4 from the glaserite process, 0.15 parts of K2SO4 were obtained from the ion exchange.
* Tr~m~rk
During the reaction and by using Solution 2 to displace saturated RCl/R2SO4 solution from the resin, a product fraction consisting of - 100 L solution containing 356 g RCl/L and 15 g R2SO4/L (Solution la) - 13.5 kg R2SO4 crystallizate and - 4.7 kg unused KCl was obtained.
After the product fraction, the following solutions were obtained as eluates:
* Trademark --8- 1 33472~
2a.) 30 L containing 246 g RCl/L and 6 g K2SO4/L, 3a.) 30 L containing 129 g KCl/L and 4 g R25O4/L, 4a.) 30 L containing 12 g KCl/L.
30 L of water remained in the exchange resin which was ready for the next loading with MgSO4 solution.
By dissolving 24.6 kg KCl, 100 L of KCl reaction solution (Solution 1) was prepared for the next exchange cycle from Solutions 2a.) to 3a.).
In addition, in each case 30 L of Solutions 2.) and 3.) were freshly prepared by dissolving 7.2 and 3.6 kg RCl respectively.
Since only traces of potassium ions remained in the exchanger, the potassium yield of the process was more than 99~.
The 100 L of product fraction (Solution 1a.) from the ion exchange process was then reacted with 64.5 kg schoenite (K2SO4 . MgSO4 . 6H2O).
The following were obtained:
- 115 L of "sulfate mother liquor" at a temperature of 39C and containing 215 g KCl/L, 87 g Mgcl2/L and 58 g MgSO4/L and - 61.2 kg K2SO4, of which 15.0 kg was from the ion exchange process.
Thus for one part of K2SO4 product obtained from the decomposition of schoenite, 0.32 parts of K2SO4 were obtained from the ion exchange.
r ~xample 2 100 L of weakly basic Kastel 102 A exchange resin loaded with Cl ions was 90% loaded with sulfate ions in an exchange column using a solution containing 40 g Na2SO4/L and 3 g NaCl/L which was adjusted to pH 4.
The salt solution was displaced from the resin bed by means of water.
Next, 170 L of solution at 50C containing 162 g KCl/L at 50C and 2 g R2SO4/L, followed by 90 L of water, were applied to the bed.
The following solutions were eluted:
1.) 17 L salt-free water, 2.) 30 L containing 2.5 g KCl/L and 2.9 g R2SO4/L, 3.) 183 L containing 83 g KCl/L and 76 g K254/L, 4.) 30 L containing 12 g RCl/L and 9 g K25O4/L-The low-salt solutions 2.) and 4.) were used to produce new KCl solution to use in the following exchange cycle. By dissolving 27.1 kg RCl in these solutions and water, 170 L of solution for charging into the exchange process was obtained.
The potassium yield was more than 99%.
The product solution 3.) of the ion exchange process contained 13.9 kg K25O4. This solution was reacted with 95.1 kg of a glaserite product having the composition Na2SO4 . 2.8K2SO4 and 56.3 kg KCl-crystallizate.
The reaction yielded the following:
- 203 L of a "sulfate mother liquor" having a temperature of 30C and containing 241 g KCl/L, 87 g NaCl/L and 25 g K2SO4/L and - 108.6 kg ~2SO4, of which 13.9 kg came from the ion exchange process.
Thus, for one part of K2SO4 from the glaserite process, 0.15 parts of K2SO4 were obtained from the ion exchange.
* Tr~m~rk
Claims (11)
1. A method for the production of potassium sulfate by means of production processes in which a sulfatic double salt accumulates, which is then decomposed in a potassium chloride solution with K2SO4 crystallizing out, characterized by the fact that the potassium chloride solution is reacted with an anion exchanger loaded with sulfate ions, and in the course of this reaction sulfate ions are desorbed from the resin and chloride ions are adsorbed, and further characterized by the fact that the resulting solution containing potassium chloride and potassium sulfate, and possibly also solid K2SO4, reacts with the sulfatic double salt and potassium sulfate is formed.
2. A method according to Claim 1, characterized by the fact that solid KCl is added to the solution flowing from the exchanger and as a result K2SO4 is crystallized out.
3. A method according to Claim 1, characterized by the fact that the chloride-loaded anion exchanger is converted to the sulfate form by using solutions of alkaline or alkaline earth sulfates.
4. A method according to Claim 1, characterized by the fact that the chloride-loaded anion exchanger is converted into the sulfate form by means of a gypsum [calcium sulfate] suspension.
5. A method according to Claim 1, characterized by the fact that the sulfate-loaded exchanger is reacted with a solution saturated with potassium chloride, and crystallizate of potassium sulfate precipitates out.
6. A method according to Claim 1 or 5, characterized by the fact that the concentration of potassium chloride solution is maintained during the exchange process by the addition of solid potassium chloride.
7. A method according to Claim 1, characterized by the fact that the sulfate-loaded exchanger is reacted with a solution unsaturated with potassium chloride and having a concentration such that no crystallizate of potassium sulfate precipitates out of the potassium chloride-potassium sulfate solution forming during the ion exchange.
8. A method according to any one of Claims 1, 2, 3, 5, 6 or 7, characterized by the fact that the ion exchange is carried out at temperatures between 10 and 80°C.
9. A method according to Claim 1, characterized by the fact that after separation of the anion exchanger, saturation with potassium chloride and precipitation of potassium sulfate, without removing the crystallizate of potassium sulfate, the reaction solutions and the suspensions containing a crystallizate of potassium sulfate which forms in accordance with the method of any one of Claims 2, 3, 5, 6 or 7, are reacted with sulfatic double salts, with further crystallizates of potassium sulfate forming.
10. A method according to Claim 1, characterized by the fact that the double salts leonite (K2SO4 . MgSO4 . 4H2O), schoenite (K2SO4 . MgSO4 . 4H2O . 6H2O), langbeinite (K2SO4 . 2MgSO4) or glaserite (3K2SO4 . Na2SO4) are reacted with the potassium chloride solution containing crystallizate of potassium sulfate from the ion exchange process.
11. A method according to any one of Claims 1-7 or 10, characterized by the fact that the potassium sulfate products from the ion exchange process and from the reaction of the double salt in another production process are jointly obtained and further processed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19873707406 DE3707406A1 (en) | 1987-03-07 | 1987-03-07 | Process for preparing potassium sulphate |
| DEP3707406.7 | 1987-03-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1334721C true CA1334721C (en) | 1995-03-14 |
Family
ID=6322542
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 560414 Expired - Fee Related CA1334721C (en) | 1987-03-07 | 1988-03-03 | Method for the production of potassium sulfate |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1334721C (en) |
| DE (1) | DE3707406A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| PL445498A1 (en) * | 2023-07-06 | 2025-01-07 | Politechnika Wrocławska | Method of producing potassium sulfate(VI) and magnesium chloride using the double ion exchange process |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4214951C2 (en) * | 1992-05-06 | 1994-06-09 | Kali & Salz Ag | Process for the production of potassium sulfate |
| ES2197736B2 (en) * | 2001-01-12 | 2004-10-16 | Minera De Santa Marta, S.A. | IMPROVED PROCEDURE FOR THE PRODUCTION OF POTASSIC SULPHATE BY THE GLASERITE METHOD. |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NZ205348A (en) * | 1982-09-02 | 1985-07-12 | Superfos As | Converting gypsum into potassium or sodium sulphate by ion exchange |
| DE3607641A1 (en) * | 1985-03-09 | 1986-12-04 | Kali Und Salz Ag, 3500 Kassel | Process for preparing potassium sulphate from potassium chloride by means of ion exchangers |
| IL78178A0 (en) * | 1985-03-27 | 1986-07-31 | Phinney Robin | Production of potassium sulphate |
-
1987
- 1987-03-07 DE DE19873707406 patent/DE3707406A1/en active Granted
-
1988
- 1988-03-03 CA CA 560414 patent/CA1334721C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| PL445498A1 (en) * | 2023-07-06 | 2025-01-07 | Politechnika Wrocławska | Method of producing potassium sulfate(VI) and magnesium chloride using the double ion exchange process |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3707406C2 (en) | 1990-10-04 |
| DE3707406A1 (en) | 1988-09-15 |
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