METHOD OF PRODUCING A GYPSUM BINDER FROM WASTES OF METALLURGICAL PRODUCTION Russian patent published in 2021 - IPC C22B7/00 C01F5/30 C01F11/24 

FIELD: hydrometallurgy.

SUBSTANCE: invention relates to the hydrometallurgy of heavy metals and can be used to extract metal compounds to obtain commercial products based on them. Gypsum binder is obtained from metallurgical waste, which is 67-70 wt. % gypsum-containing sludge, 28-30 wt. % off-gas hydrochloric acid and 2-3 wt. % dolomite entrainment dust. Gypsum-containing sludge is treated in a reactor with off-gas hydrochloric acid to obtain a suspension containing ferric chloride and gypsum. The resulting suspension is separated into sludge containing gypsum and 20-25% ferric chloride solution, and a liquid coagulant in the form of ferric chloride solution. The resulting sludge is neutralized in a reactor with dolomite entrainment dust until a pH of 7.5-8.0 is reached with the formation of mixture containing magnesium and calcium chlorides with an admixture of iron oxide. The resulting mixture is cooled in a two-roll mixer to obtain a suspension containing crystalline hydrates of magnesium chloride and calcium chloride. Moreover, magnesium chloride crystalline hydrate is formed at temperatures below 116.9 ºC, and calcium chloride crystalline hydrate - at temperatures below 30.2 ºC. The suspension is dried at a temperature of 110-120 ºC for 15-20 minutes in a combined fluidized-bed dryer and ground to a size of 4-5 mm to obtain gypsum binder containing gypsum, magnesium chloride and calcium chloride.

EFFECT: method increases the strength of the resulting binder.

1 cl,1 dwg, 1 tbl