METHOD OF RECOVERING MAGNESIUM FROM SILICON-CONTAINING WASTES Russian patent published in 2004 - IPC

FIELD: nonferrous metallurgy.

SUBSTANCE: invention, in particular, relates to production of magnesium from electrolysis of molten salts. Silicon-containing waste is first ground and separated into fractions. The latter are leached with hydrochloric acid solution to form magnesium chloride suspension, which is separated into solution and precipitate. Solution is purified and concentrated, after which subjected to multistage dehydration to give anhydrous magnesium chloride raw material for electrolysis. Electrolysis produces magnesium, chlorine, and electrolyte. Chlorine is converted into hydrogen chloride sent to electrolysis raw material preparation stages. Electrolyte is also returned into raw material preparation stages. Novelty of invention resides in that separated precipitate is washed to remove chloride ions and dried to form silica concentrate; solution is purified in two steps: first to achieve pH 3.5-4.0 and then to pH 10.0-11.0, after which suspension is filtered to give magnesium chloride solution and iron-nickel-cobalt concentrate. Silicon-containing wastes utilized are coarse-grain grit and/or load streams, or broken rock, which are produced in the process of manufacturing asbestos fiber from serpentinite.

EFFECT: reduced amount of waste formed in production of magnesium, simplified procedure, and produced new commercial products.

12 cl