Method for the preparation of lactic acid and calcium sulphate dihydrate

Abstract

The invention relates to a method for the preparation of lactic acid and calcium sulphate, in which (a) an aqueous solution that contains lactate is reacted with sulphuric acid at a temperature that is essentially higher than the transition temperature of calcium sulphate dihydrate (CaSO4.2H2O), with the formation of a mixture that contains calcium sulphate hemihydrate and lactic acid, (b) the mixture from step (a) is subjected to at least one recrystallisation step at a temperature that is essentially lower than the transition temperature of calcium sulphate dihydrate, with the formation of a precipitate of calcium sulphate dihydrate and an aqueous solution of lactic acid, and (c) the precipitate of calcium sulphate dihydrate is separated off from the aqueous solution of lactic acid.

Dependencies are inferred from the claim text.