关键词: 磷尾矿, 碳化法, 氢氧化镁, 碳酸钙

Abstract: For the recovery of magnesium，calcium，and phosphorus in the phosphorus tailings，secondary water washing，and secondary carbonation were used for extraction of magnesium and calcium to prepare magnesium hydroxide and calcium carbonate respectively and meanwhile increase phosphorous content in the tailings.With 110 ℃ drying of phosphate tailings，it was crushed to 122~180 μm and calcined.The calcined phosphate tailings was added into distilled water，and washed at a constant temperature（first washing），and then filtrate it. Passed CO2 into the filter liquor for carbonization（first carbonization）， and then filtrated it to obtain calcium carbonate and the filter liquor return to the first washing; the filter residue was washed（second washing） again under the same conditions，while ventilating CO2 for carbonization，carbonized solution after vacuum filtration，and the filter liquor was magnesium bicarbonate，aqueous ammonia was added to form magnesium hydroxide precipitate，again by vacuum filtration separating solid magnesium hydroxide，and the residue was mainly phosphate ore.The results showed that the magnesium and calcium could be separated well from phosphorus tailings by secondary water washing and secondary carbonation and the final products of hydroxide magnesium and calcium carbonate could reach more than 96% and 99%（mass fraction），respectively，and the mass fraction of P2O5 in the tailings increased from 5.79% to 14.91%.

Key words: phosphate tailings, carbonation, magnesium hydroxide, calcium carbonate