Sulfur content reduction of iron concentrate by reverse flotation

In this study, the desulphurization of iron ore concentrate using reverse flotation was investigated. In this paper first, behavior of the flotation of both pure ? pyrite and iron oxides-pyrite with xanthate has been examined based on micro-flotation results and zeta-potential measurements. Then, an effort has been made to investigate the effect of pH, chemical reagent dosages, impeller speed, pulp density, flotation time and conditioning time parameters on desulphurization of actual iron ore concentrate using lab-scale mechanical flotation cell. Results of zeta-potential measurements displayed that iso-electric points (IEP) for pure and iron oxides-pyrite were around pH 7 and 8, respectively. Based on the micro-flotation results, the recoveries were highly dependent on pH. Both pyrite types showed high recoveries at pH 4.75 to 8, but in the flotation of iron oxides-pyrite, partial depression was found in the pH range of 6?7. The presence of iron ions in solution considerably depressed iron oxide-pyrite flotation in the pH range of 2.5?3. Recovery of both pyrites decreased dramatically when going from pH 10, due to the formation of iron hydroxides and the instability of dixanthogen. According to the data obtained from batch flotation tests, the maximum recovery of total sulfur was achieved when the operational parameters were set to the PAX dosage 200 gr/t, MIBC dosage 150 gr/t, CuSo(4) 75 gr/t, impeller speed 1500 rpm, pH 7.5, flotation time 7 min and pulp density 30%. With these optimum parameters, final concentrate with the grade of 69.48% Fe and 0.1% S was obtained.