Method for preparing sodium chloride and magnesium sulphate heptahydrate with brine

Abstract

The invention discloses a method for using brine to produce sodium chloride and heptahydrate magnesium sulfate, comprising the steps that: (1) brine is taken as a raw material, the molar ratio of SO4<2->:Mg<2+> in the brine is 0.1-0.8, and the molar ratio of SO4<2->:Na<+> is 0.025-1; and the pressure is decreased for boiling evaporation, the pressure is controlled to make the boiling temperature be 75 DEG C to 50 DEG C after the evaporation, and the molar ratio of SO4<2>:Na<+> in the solution is 0.4-2.5; (2) solid-liquid separation is implemented, and the solid phase is washed with saturated sodium chloride aqueous solution and is then dried for obtaining the sodium chloride; (3) a mother liquid of salt production is added with water to prepare a mixture; (4) the mixture is cooled and guided into a crystallizer, then crystals are separated out; and (5) solid-liquid separation is carried out for obtaining a crude product having a solid phase of heptahydrate magnesium sulfate. The method has advantages of simple equipment, simple process, complete separation of sodium chloride, high purity and yield of heptahydrate magnesium sulfate, having no miscellaneous salt removing link in the process, and realizable joint production of sodium chloride and heptahydrate magnesium sulfate.

Description

technical field

[0001] The invention relates to the field of salt production, in particular to a method for producing sodium chloride and magnesium sulfate heptahydrate from brine. Background technique

[0002] Brine salt is currently widely used to make salt by beach-drying evaporation, or beach-drying saturated brine to make salt by vacuum evaporation. The salt-making mother liquor of the existing salt-making method is either discharged or comprehensively utilized by traditional methods. The way of using discharge is not friendly to the environment. The traditional comprehensive utilization method is centered on the production of potassium chloride by adding brine. The main products are potassium chloride, magnesium chloride (halogen flakes, halogen powder), sodium sulfate, bromine, etc. The salt making mother liquor is mixed with the bromine extracting mother liquor with magnesium chloride as the main component so that the concentration ratio of magnesium sulfate and ma...

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