Patent ID: 7789159

Claim:
A method for separating sulfate from saline water to produce nearly sulfate-free saline stream and inorganic materials, said method comprising the steps of: (a) removing sulfate from said saline water by (i) mixing calcium chloride rich formation water with said saline water to allow the concentration of the calcium ion to exceed the concentration of the sulfate ion in said saline water to produce intermediate concentrate; (ii) pressurizing said intermediate concentrate into a precipitator at pressure between 50 psi and 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 50 psi and the critical pressure of said amine solvent or said amine solvent with modifier through at least one nozzle to form precipitates comprising gypsum from said intermediate concentrate; (iv) removing said 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; or (c) feeding said nearly sulfate-free saline stream into conventional seawater desalinations plants and auxiliary equipments; or (d) producing de-ionized water from said nearly sulfate-free saline stream by membrane distillation; (e) 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 (f) producing potassium sulfate and calcium chloride from said gypsum slurry by (i) adding sylvite or sylvinite 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; (v) recycling said intermediate liquor stream comprising at least dissolved calcium chloride to said intermediate concentrate; or (vi) recovering said intermediate liquor stream comprising at least calcium chloride brine.