Synchronous Desulfurization and Desilication of Low-Grade and High-Sulfur Bauxite by a Flotation Process

Abstract

The existence of sulfur and silica in bauxite influence the product quality of Bayer alumina. The synchronous desulfurization and desilication of low-grade and high-sulfur bauxite through reverse flotation processes were studied using modified starch as depressants in this work. The effects of depressant dosage, modified depressant dosage and collector dosage on flotation performance were investigated. The results show that the sulfur and silica in bauxite were 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, modified depressant dosage of 50 g/t, copper sulfate dosage of 20 g/t, combined collector dosage of 220 g/t, and terpenic oil dosage of 120 g/t, the recovery of Al2O3 reached to 76.41%. The sulfur content of concentrate was decreased from 2.87 to 0.27%, with an aluminum to silicon ratio (A/S) increasing from 3.36 to 8.09.