METHOD OF REDUCING CONTENT OF CALCIUM IONS IN WASTE WATER Russian patent published in 2011 - IPC C02F5/02 C02F1/58 C02F1/54 

FIELD: chemistry.

SUBSTANCE: invention can be used in mineral processing using a floatation method, where content of calcium in recycled water is limited. Calcium ions are removed from waste water through successive addition of a carbonate of an alkali metal and an alkali with subsequent separation of the residue which is difficult to dissolve. The alkali metal carbonate used is calcined soda. After adding an alkali to pH 11.0-11.5, an anionic surfactant - crude tall oil soap - is added to form floccule, and a coagulant - iron sulphate, is added. To intensify formation of floccule and increasing the rate of precipitation, concentration of anionic surfactants is 20-70 mg/l. To remove the formed floccule through floatation, concentration of anionic surfactants is 50-100 mg/l.

EFFECT: invention ensures content of calcium in purified water of up to 1 mg/l and rate of precipitation higher than 0,16 mm/s.

3 cl, 1 tbl, 6 ex