Sulfate Ion → Calcium Sulfate Dihydrate

Participants

Reaction Steps

A brine containing 0.77% lithium in the form of lithium chloride, and 0.28% boron, as well as magnesium and sulfate impurities, was treated with a slurry of slaked lime to a pH of 11.2 to precipitate magnesium as magnesium hydroxide and then treated with a sufficient amount of a 20% solution of calcium chloride to form calcium tetra borate (CaB2O4.6H2O), and gypsum. At pH 11.2, only gypsum precipitated and boron was reduced to 0.15%B due to a dilution effect. Upon concentrating the brine by evaporation, to 40% Li, calcium tetraborate hydrate precipitated and the boron was maintained at 0.13%B.

Provenance & Evidence