METHOD FOR PRODUCING MAGNESIUM OXIDE FROM BISCHOFITE Russian patent published in 1997 - IPC

FIELD: chemical industry. SUBSTANCE: starting natural bischofite is subjected to filtering to eliminate mechanical impurities, followed by precipitating magnesium hydroxide from liquor by treating latter with ammonia gas or with ammonia water at pH=10.0-10.5. Precipitated magnesium hydroxide is separated from mother liquor and latter is treated with ammonium carbonate at pH=11.0-11.5 to precipitate all remaining magnesium. Precipitates recovered at both process steps are washed and subjected to heat treatment at 500-700 C for 1-2 h to produce MgO. Magnesium chloride solution formed in magnesium hydroxide precipitation step is treated to remove from it ammonia excess and pumped back to borehole, from which natural bischofite is extracted. Proposed method can be used for processing other chlorine- and magnesium-containing solutions and liquors. EFFECT: simple process for producing magnesium oxide.