GYPSUM PREPARATION METHOD Russian patent published in 2010 - IPC C01F11/46 

FIELD: chemistry.

SUBSTANCE: invention relates to chemistry and can be used in production of gypsum. Calcium carbonate and sulphuric acid are simultaneously added to water. Sulphuric acid is taken in concentration of 60-93% in stoichiometric amount of 103-120% and the obtained gypsum pulp is held at 70-85°C for 3.5-5 hours, filtered and washed and gypsum residue is separated and dehydrated. Calcium carbonate is taken with particle size of up to 250 mcm or in form of a suspension - chalk production wastes with solid to liquid ratio of 1:(0.5-1.5). Gypsum residue is dehydrated by drying at temperature not higher than 60°C or by centrifuging followed by pressing. When dehydrating gypsum through centrifuging with subsequent pressing, neutralising agents such as chalk or lime are added at the step for holding the gypsum pulp before filtration. The calcium carbonate used is in form of conversion chalk.

EFFECT: invention simplifies the process and enables to obtain gypsum with minimal impurity content.

5 cl, 4 tbl, 1 ex