METHOD OF PROCESSING NATURAL AND MAN-MADE SILICON-CALCIUM-CONTAINING CONCENTRATE WITH PHOSPHORUS ADMIXTURE Russian patent published in 2001 - IPC

FIELD: inorganic compounds technology. SUBSTANCE: concentrate is treated with 2-12% sulfuric acid to achieve in liquid phase Ca/P/S weight ratio 1:(0.1-10):(0.02-0.4), after which precipitate is separated from liquid phase and washed out with water. Sulfuric acid treatment of concentrate and washing of petroleum precipitate are carried out in suspended bed by supplying, respectively, acid-air mixture and water-air mixture at velocity 5 to 50 cm/s and temperature between 5 and 18 C. Content of phosphorus impurity is thus reduced by 96.4-98.9% and sulfur trioxide level drops to 0.005-0.09%. EFFECT: improved purity of material enabling its use in welding electrode coating compositions. 2 cl, 1 tbl, 13 ex