METHOD OF PRODUCTION OF CHROMITE CONCENTRATE Russian patent published in 2007 - IPC C22B34/32 

FIELD: complex processing of non-traditional kinds of raw materials - serpentinites and serpentinite waste of gaugue into chrysotile-asbestos and chromite deposits; production of chromite concentrate from lean chromium-containing ores.

SUBSTANCE: proposed method includes grinding of ore, heat treatment, leaching-out by mineral acid solutions followed by filtration of suspension, washing and drying of end product. Heat treatment is performed at temperature of 500-550^°C ; leaching-out and filtration processes are performed in two stages including additional treatment of solid residue by caustic soda solution followed by filtration. First leaching-out stage consists in treatment of roasted ore by acid circulating filtrate at concentration of 230-250 g/l or sulfuric acid of hydrochloric acid at concentration of 90-110 g/l followed by filtration of suspension and transfer of solid residue to the second stage. Second stage includes treatment of solid residue by solution of sulfuric or hydrochloric acid at concentration of 300-550 g/l and 110-220 g/l, respectively followed by filtration of suspension and transfer of filtrate to the first leaching-out stage.

EFFECT: extended field of application of use of lean ore mixtures at simultaneous complex extraction of valuable components from raw material.

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