METHOD OF PRODUCING CALCIUM BROMIDE FROM NATURAL BROMINE-CONTAINING CALCIUM CHLORIDE-TYPE BRINES Russian patent published in 2012 - IPC C01F11/34 

FIELD: chemistry.

SUBSTANCE: invention can be used in chemical industry. The method of producing calcium bromide from natural bromine-containing brines involves oxidation of bromide ions contained in the brine with chlorine, desorption of bromine vapour, capturing bromine with a calcium reagent in the presence of a reducing agent. The calcium reagent used is calcium carbonate which is extracted from brine after crystallisation of CaCl₂·6H₂O with a MgCl₂·6H₂O impurity. To obtain calcium carbonate, a residue of CaCl₂·6H₂O and MgCl₂·6H₂O is used, which is dissolved in water and the solution is purified from magnesium hydroxide. After precipitation of calcium carbonate, the mother solution, which contains sodium chloride, undergoes electrolysis to obtain chlorine and a catholyte containing sodium hydroxide. Calcium carbonate is precipitated from brine using said catholyte with simultaneous carbonisation of the reaction mixture or with the catholyte after carbonisation thereof. Purification from magnesium hydroxide is also carried out with the obtained catholyte. Chlorine obtained from electrolysis is used to oxidise bromide ions to molecular bromine. The vapour-bromine mixture is used as the brominating agent for calcium carbonate pulp in a solution of a reducing agent. The reducing agent used is hydrazine or hydroxylamine or derivatives thereof.

EFFECT: invention enables to use highly mineralised brines to obtain reagents for producing calcium bromide in a single process scheme.

2 cl, 1 dwg, 1 tbl, 3 ex