METHOD OF PRODUCING MAGNESIUM AND CALCIUM CHLORIDE CRYSTAL-DYDRATES FROM INDUSTRIAL WASTES Russian patent published in 2019 - IPC C01F5/30 C01F11/24 

FIELD: chemistry.

SUBSTANCE: invention relates to chemical engineering. Method of producing crystalline hydrates of magnesium and calcium chloride from industrial wastes involves neutralization of a solution of hydrochloric acid with carbonates. Hydrochloric acid used is spent hydrochloric acid etching solutions. Carbonates used are dolomite production wastes – dolomite dust. Reaction is carried out at temperature of 90–95 °C. After completion of the neutralization reaction from the obtained suspension in the hot form, iron hydroxide is separated on the filter, which is processed into yellow and red iron oxide pigments. Obtained filtrate is evaporated at 130–140 °C to contain 46 wt% magnesium chloride, followed by crystallisation at 40–50 °C. Precipitated crystals are separated by a centrifuge, dried and ground in a combined drier at 120–130 °C to obtain magnesium chloride crystalline hydrate. Centrifuge-separated filtrate containing calcium chloride is subjected to crystallisation by spraying at 300±0.5 °C in a spray dryer, wherein crystal calcium chloride is obtained.

EFFECT: efficient method of producing crystalline hydrates of magnesium and calcium from industrial wastes at low power consumption.

1 cl, 1 dwg, 3 tbl, 2 ex