METHOD OF RECYCLING GYPSIFEROUS RAW MATERIALS Russian patent published in 2008 - IPC C01F11/46 B03D1/02 

FIELD: construction.

SUBSTANCE: method of recycling gypsiferous raw materials involves re-pulping gypsiferous waste product, cleaning it, re-crystallisation of the gypsum in an autoclave into a hemihydrate of calcium sulphate, drying and grinding. Boric gypsum, a waste product of boric production is used as the gypsiferous material. There is extraction of dehydrate of calcium sulphate through floatation in foam material using floatation reagents. The reagents used are a mixture of sodium salts of fatty acids:- natrium oleat, natrium stearate and natrium palmitate, with mass ratios 2:1.5:0.5 respectively, added in quantities of 0.1-0.3 kg/t of boric gypsum sludge, and liquid sodium glass, added in quantities of 0.02-0.05 kg/t of boric gypsum sludge. Dehydration of the dehydrate of calcium sulphate is done after processing of sulphuric acid and the calcium hydrate in the pH range 2-7.

EFFECT: invention allows for recycling of gypsiferous waste products from boric production and increased technological effectiveness of the process.

6 ex, 1 tbl, 1 dwg