METHOD OF MAGNESIUM OXIDE PRODUCING FROM SERPENTINITE Russian patent published in 1994 - IPC

FIELD: chemical technology. SUBSTANCE: method involves melting of serpentinite with ammonium sulfate at 250-400 C, product is leached with water, and impurities of Ca, Fe, Ni, Co, Si etc. from magnesium sulfate obtained are removed by precipitation in the form of hydroxides by fractional neutralization. Precipitate is separated by filtration, and Mg(OH)₂ is precipitated firstly from the filtrate with ammonia at pH 10.0-10.5, and then magnesium carbonate is precipitated with ammonium carbonate at pH 11.0-11.5. Both precipitates are washed off from sulfate ions and subjected for thermal treatment at 750 C with magnesium oxide production. The solution of ^Mg(OH)2 prepared at the stage of (NH₄)₂SO₄ precipitation is concentrated by evaporation, granulated and directed to the caking stage with serpentinite. Ammonia evolved at this stage is condensed and recirculate to the stage of Mg(OH)₂ precipitation. Degree of Mg(OH)₂ precipitation is 98-100% . EFFECT: improved method of magnesium oxide producing.