Flotation separation of pyrite from refractory high-sulfur bauxite

Abstract

The existence of pyrite results in high soda consumption, iron pollution of alumina oxide and pipeline corrosion in the utilization of high-sulfur bauxite during the production of Bayer alumina. The flotation desulfurization of high-sulfur diasporic bauxite with modified 2-mercaptobenzimidazole (MBI) collector was studied in this work. The effects of pulp pH, collector dosage, activator dosage and frother dosage on flotation performance (the sulfur content in concentrate and Al2O3 recovery) were examined. The results indicate that the sulfur in bauxite was successfully decreased through the reverse flotation. With an optimal condition of 10% solid density, particle size of −74 µm of 75%, pulp pH 9, temperature 30 °C, collector dosage of 120 g/t, copper sulfate dosage of 20 g/t, and terpenic oil dosage of 120 g/t, the recovery of Al2O3 reached to 77.58%. The sulfur content of concentrate was decreased from 2.87 to 0.66%, with an aluminum to silicon ratio (A/S) increasing from 3.36 to 4.43.