Patent ID: 7638109

Claim:
A process for the production of crystalline sodium sesquicarbonate and sodium carbonate from a solution minewater stream comprising (a) withdrawing an aqueous minewater stream containing sodium carbonate and sodium bicarbonate from a solution mining cavity in a subterranean alkali ore deposit; (b) crystallizing, in a first crystallizer operation, sodium sesquicarbonate from the aqueous minewater stream, the crystallization being carried out in the sodium sesquicarbonate region of the sodium carbonate-sodium bicarbonate-water system phase diagram without significant co-crystallization of other alkali species, and wherein the aqueous minewater stream introduced into the first crystallizer is substantially free of added sodium carbonate calcinate selected from the group consisting of calcined sodium sesquicarbonate and calcined trona ore; (c) separating crystalline sodium sesquicarbonate from mother liquor in the first crystallizer slurry and recovering crystalline sodium sesquicarbonate as a first product; (d) converting at least a portion of residual dissolved sodium bicarbonate in the separated first crystallizer mother liquor to carbonate, in a treatment sufficient to permit crystallization of sodium carbonate monohydrate from the treated first crystallizer mother liquor as the sole crystalline species; (e) crystallizing, in a second crystallizer operation, sodium carbonate monohydrate from the separated and treated first crystallizer mother liquor, wherein the separated first crystallizer mother liquor introduced to the second crystallizer is substantially free of added sodium carbonate calcinate selected from the group consisting of calcined sodium sesquicarbonate and calcined trona ore; (f) separating crystalline sodium carbonate monohydrate from mother liquor in the second crystallizer slurry and recovering the crystalline sodium carbonate monohydrate; and (g) drying the recovered crystalline sodium carbonate monohydrate to produce dense soda ash, as a second product.