Abstract: Although U.S. Pat. No. 8,182,784 teaches the recovery of potassium chloride from schoenite end liquor (SEL) using dipicrylamine as extractant, and consequently simplifies the recovery of sulphate of potash (SOP) from kainite mixed salt employing the scheme disclosed in U.S. Pat. No. 7,041,268, the hazards associated with this extractant have thwarted practical utilization of the invention. Many other extractants for potash recovery have been disclosed in the prior art but none has been found suitable so far for practical exploitation. It is disclosed herein that the bitartrate ion, and particularly L-bitartrate, precipitates out potassium bitartrate very efficiently from SEL with ca. 90% utilization of the extractant. In contrast, recovery of potassium bi-tartrate from sea bittern directly is relatively much lower. It is further disclosed that this precipitate can be treated with magnesium hydroxide and magnesium chloride to throw out magnesium tartrate with ca.

Abstract: Although U.S. Pat. No. 8,182,784 teaches the recovery of potassium chloride from schoenite end liquor (SEL) using dipicrylamine as extractant, and consequently simplifies the recovery of sulphate of potash (SOP) from kainite mixed salt employing the scheme disclosed in U.S. Pat. No. 7,041,268, the hazards associated with this extractant have thwarted practical utilization of the invention. Many other extractants for potash recovery have been disclosed in the prior art but none has been found suitable so far for practical exploitation. It is disclosed herein that the bitartrate ion, and particularly L-bitartrate, precipitates out potassium bitartrate very efficiently from SEL with ca. 90% utilization of the extractant. In contrast, recovery of potassium bi-tartrate from sea bittern directly is relatively much lower. It is further disclosed that this precipitate can be treated with magnesium hydroxide and magnesium chloride to throw out magnesium tartrate with ca.

Abstract: The present invention relates to a process for the recovery of sulphate of potash (SOP) from bittern. Kainite is obtained by fractional crystallization of the bittern. Kainite is converted into schoenite with simultaneous removal of NaCl and the filtrate (SEL) is used for production of KCl. Schoenite is reacted with aqueous KCl to yield SOP and the filtrate (KEL) is recycled in the kainite to schoenite conversion step. The production of KCl from SEL is carried out with the aid of dipicrylamine (DPA). Lime is treated with DPA in water for the production of highly soluble Ca (DPA)2, which in turn treated with SEL to produce insoluble K(DPA). K(DPA) is treated with HCl to produce KCl and insoluble DPA, which can be recycled for the production of Ca (DPA)2. The aqueous KCl thus obtained is treated with schoenite to prepare SOP. The KEL obtained along with SOP is recycled to generate schoenite.

Abstract: The present invention relates to a process for the recovery of sulphate of potash (SOP) from bittern. Kainite is obtained by fractional crystallization of the bittern. Kainite is converted into schoenite with simultaneous removal of NaCl and the filtrate (SEL) is used for production of KCl. Schoenite is reacted with aqueous KCl to yield SOP and the filtrate (KEL) is recycled in the kainite to schoenite conversion step. The production of KCl from SEL is carried out with the aid of dipicrylamine (DPA). Lime is treated with DPA in water for the production of highly soluble Ca (DPA)2, which in turn treated with SEL to produce insoluble K(DPA). K(DPA) is treated with HCl to produce KCl and insoluble DPA, which can be recycled for the production of Ca (DPA)2. The aqueous KCl thus obtained is treated with schoenite to prepare SOP. The KEL obtained along with SOP is recycled to generate schoenite.