Abstract:

Using high-magnesium phosphate tailings as raw materials,the carbonization method was used to separate phospho-rus,magnesium,and calcium in the phosphate tailings,and basic magnesium carbonate and phosphate concentrates were ob-tained through processes such as calcination,digestion,carbonization,and pyrolysis treatment.The experimental results sho-wed that the digested slurry after calcining the high-magnesium phosphate tailings was firstly carbonized at atmospheric pre-ssure and then carbonized under pressure.The conditions of the pressure carbonization were that the mass concentration of the slurry was 12.0~13.5 g/L and the partial pressure of carbon dioxide was 0.18 MPa,carbonization end temperature was 25 ℃, under these conditions the recovery rate of magnesium reached 87%~90%,the mass fraction of phosphorus pentoxide obta-ined from the phosphate concentrate reached 28%~30%,and the recovery rate of phosphorus was 60%~65%;The heavy magnesium water obtained after two-step carbonization was pyrolyzed.The pyrolysis conditions were that the mass concentra-tion of heavy magnesium water was 10~12 g/L,the vacuum degree was 0.085 MPa,the pyrolysis temperature was 60 ℃,and the pyrolysis time was 50 minutes,the mass concentration of magnesium oxide in the filtrate obtained under these conditions was 0.7 g/L,and the recovery rate of magnesium was 93%.Using high-magnesium phosphate tailings as raw materials,basic magnesium carbonate was prepared by carbonization method.The quality of the product was analyzed to meet the requirements of HG/T 2959—2010 “Industrial Hydrated Basic Magnesium Carbonate”.The carbonization method was used to treat high-magnesium phosphorus tailings,and the recovery rate of phosphorus and magnesium was high.This method provided an effec-tive technical approach for the recovery and utilization of high-magnesium phosphate tailings in China.

Key words: high-magnesium phosphate tailings, carbonization method, basic magnesium carbonate, phosphate concentrate