Process for Recovery of Sulfur from Gypsum.
U S Pat 3 591 332 1971 Jul; :
S and na2co3 are produced from gypsum, nacl, and c by a stepwise process consisting of (1) roasting a mixture of gypsum and c to form cas; (2) treating the cas with h2s and h2o to prepare an aqueous ca(hs)2 solution; (3) bringing the solution into contact with a strongly acid cation-exchange resin in the na form to prepare an aqueous nahs solution free of ca; and (4) carbonating the solution to liberate h2s and precipitate nahco3. The h2s is converted to s or h2so4 and the nahco3 to na2co3 by usual methods. The spent ion exchange resin is regenerated with aqueous nacl solution.
U.S. Pat. 3,591,332; July 6, 1971; Chem. Abstr. 75:78,670M