The effect of column flotation operational variables on desulfurization of iron ore concentrate

Fine particles of pyrite are not recovered completely by magnetic separators in presence of iron ores such as magnetite and hematite. Reverse flotation is an effective method to reduce sulfur from magnetic separators concentrate. The aim of this study is to investigate the effect of operational variables on flotation column performance in desulphurization process from iron concentrate and to optimize operational conditions for the sake of achieving the maximum sulfur recovery with the minimum iron waste. To do so, by conducting 45 tests, based on a central composite design (CCD), the effect of important operational factors including gas flow rate, froth depth, slurry solids percent, frother/collector dosage and pH was considered. The iron ore sample was collected from magnetic separators concentrate stream of Gole Gohar iron ore complex with d80 equal to 90µm. Sulfur and total Fe contents of the sample were found to be 0.48% and 63.3%, respectively. Optimized operational conditions were predicted to obtain the minimum and maximum values for concentrate and tailing sulfur grades respectively via the use of significant factors and variance analysis. Based on the results of ANOVA, the optimum values of column operation parameters were 150 gr/t of PAX, 200 gr/t of MIBC, 20 cm froth depth, 1.6 cm/s of air flow rate, pH of 4.9 and a solid concentration of 30%. By applying operational optimum conditions, concentrate sulfur grade at significant level of 95%, tailing sulfur grade and iron recovery were equal to 0.08%, 34% and 98%, respectively.