Patent ID: 7392848

Claim:
A method for separating sulfate from saline water to produce nearly sulfate-free saline stream and gypsum, said method comprising the steps of: (a) removing sulfate from said saline water by (i) concentrating said saline water by membrane system to produce an intermediate concentrate comprising at least gypsum, said gypsum having an increased concentration in said intermediate concentrate; (ii) pressurizing said intermediate concentrate into a precipitator at pressure between about 400 psi and about 1,200 psi through at least one nozzle to produce a jet stream of said intermediate concentrate; (iii) pressurizing amine solvent or amine solvent with modifier into said precipitator at pressure between about 400 psi and about the critical pressure of said amine solvent or said amine solvent with modifier through at least one nozzle to form micron-size precipitates comprising said gypsum from said intermediate concentrate; (iv) removing said micron-size precipitates from said intermediate concentrate by filter to produce gypsum slurry; (v) removing at least most of said amine solvent or said amine solvent with modifier from said intermediate concentrate by stripper to produce said nearly sulfate-free saline stream; (b) injecting said nearly sulfate-free saline stream into subterranean formation for hydrocarbons recovery; (c) producing gypsum boards or gypsum materials from said gypsum slurry by (i) separating said gypsum slurry into moist solid gypsum and liquor stream by filter; (ii) removing at least most of remaining said amine solvent or said amine solvent with modifier from said liquor stream by stripper; (iii) recycling said liquor stream to said intermediate concentrate; (iv) molding said moist solid gypsum to produce said gypsum boards or said gypsum materials; (v) allowing said gypsum boards or said gypsum materials to dry; or (d) producing potassium sulfate from said gypsum slurry by (i) adding potassium chloride to said gypsum slurry to produce intermediate liquor stream; (ii) adding said amine solvent or said amine solvent with modifier to said intermediate liquor stream to form precipitates comprising said potassium sulfate; (iii) removing said precipitates from said intermediate liquor stream by filter; (iv) removing at least most of said amine solvent or said amine solvent with modifier by stripper; and (v) recycling said intermediate liquor stream comprising at least dissolved calcium chloride to said intermediate concentrate.