# US 9,517,943 B2 · Integrated process of production of potassium sulphate and ammonium sulfate from kainite mixed salt > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,517,943 B2 - Document ID: US9517943B2 - Status: Granted - Kind: B2 - Application number: 14/424,938 - Filed: 2013-09-02 - Published: 2015-08-13 - Granted: 2016-12-13 - Earliest claimed: 2012-09-02 - Assignees: Council of Scientific and Industrial Research - Applicants: Council of Scientific and Industrial Research - Inventors: Pushpito Kumar Ghosh; Pratyush Maiti; Maheshkumar Ramniklal Gandhi - Web page: https://patentgrep.com/patent/US9517943B2 ## CPC - C01D 5/00: Sulfates or sulfites of sodium, potassium or alkali metals in general {(sulfites in general C01B17/62)} - C01C 1/24: Sulfates of ammonium (C01C1/14 takes precedence) - C01D 3/04: Chlorides - Y02P 20/10: Process efficiency - C01D: COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides C01B17/22; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia and cyanogen, containing nitrogen and other non-metals C01B21/082}; metal amides C01B21/092; nitrites C01B21/50; phosphides C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20) - C01C: AMMONIA; CYANOGEN; COMPOUNDS THEREOF ({metal hydrides, monoborane, diborane or addition complexes thereof C01B6/00}; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; azides C01B21/08; {compounds other than ammonia or cyanogen, containing nitrogen, non-metals and optionally metals C01B21/082}; metal imides or amides C01B21/092; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; compounds containing silicon C01B33/00; compounds containing boron C01B35/00) - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract The present invention provides an integrated process for the recovery of sulphate of potash (SOP) and ammonium sulphate fertilizers from kainite mixed salt dispensing with magnesium hydroxide production. The process comprises, among other steps, producing calcium chloride from calcium carbonate through addition of hydrochloric acid; the calcium chloride being used for desulphatation of schoenite end liquor (SEL) obtained as liquid stream during decomposition of kainite mixed salt with water to obtain solid schoenite; using the resultant gypsum and carbon dioxide together with ammonia for the production of ammonium sulphate liquor and solid calcium carbonate, the latter being recycled in the process; producing carnallite from desulphated SEL; decomposing the carnallite to recover carnallite decomposed product (CDP) which is further refined under ambient conditions to obtain pure potassium chloride (KCl) utilized in the preparation of SOP from the schoenite. Except for ammonium sulphate recovery in solid state, where required, all operations are carried out at ambient temperature. ## Claims ### Claim 1 An integrated process for the production of potassium sulphate and ammonium sulfate from a kainite mixed salt, dispensing with magnesium hydroxide production, the process comprising the steps of: i. adding hydrochloric acid in calcium carbonate to produce 30-40% w/v concentrated calcium chloride and pressurized carbon dioxide (CO2); ii. decomposing the kainite mixed salt with water to obtain solid schoenite and schoenite end liquor (SEL) as a liquid stream; iii. desulphatizing the SEL as obtained in step (ii) using the calcium chloride as obtained in step (i) to produce desulphated SEL and gypsum; iv. subjecting the gypsum as obtained in step (iii) and the pressurized CO2 as released in step (i) together with ammonia for the production of ammonium sulphate liquor and solid calcium carbonate, the latter being recycled in step (i); v. producing carnallite from the desulphated SEL as obtained in step (iii), decomposing the carnallite to obtain carnallite decomposed product (CDP) along with carnallite decomposed liquor (CDL), the latter being recycled in desulphated SEL; vi. wet sieving the CDP as obtained in step (v) followed by aqueous leaching of fines fraction, obtained upon wet sieving, to obtain potassium chloride (KCl) (purity >98%); vii. utilizing the potassium chloride, as obtained in step (vi) in the preparation of sulphate of potash (SOP) from the schoenite as obtained in step (ii). ### Claim 2 (depends on 1) The process as claimed in claim 1, wherein the CO2 gas generated in step (i) is auto-pressurized to 2 kg/cm2g without additional energy input, wherein the auto generated pressure is adequate for the purpose of a subsequent Merseberg reaction. ### Claim 3 (depends on 2) The process as claimed in claim 2, wherein the auto-pressurized CO2 is used in a Merseberg reaction. ### Claim 4 (depends on 1) The process as claimed in claim 1, wherein the CDP is refined by wet sieving based on differences in the sizes of NaCl and KCl crystals, respectively, the former being significantly larger. ### Claim 5 (depends on 1) The process as claimed in claim 1, wherein the KCl separated by wet sieving is further refined by aqueous leaching of residual NaCl. ### Claim 6 (depends on 1, 5) The process as claimed in claim 5, wherein the CDL as obtained in step (v) is recycled back in step (v) of claim 1 to minimize KCl loss. ### Claim 7 (depends on 1) The process as claimed in claim 1, wherein the steps related to recovery of the KCl from desulphated SEL, comprising steps (v) & (vi), are carried out under ambient temperature. ### Claim 8 (depends on 7) The process as claimed in claim 7, wherein the ambient temperature range is 26-30° C.