Application of the response surface method (RSM) based on central composite design (CCD) and design space (DS) to optimize the flotation and the desliming conditions in the recovery of PGMs from mine sludge

This investigation focuses on the application of the response surface methodology (RSM) through central composite design (CCD) and design space (DS) to study and optimize the desliming impact on the flotation recovery of platinum group metals (PGMs) from mine sludge. The correlation between independent and dependent variables were determined. pH and pulping effect for the desliming and pH, MIBX, CuSO₄, (NH₄)₂SO₄, mixt depressants, and flotation time for the flotation were investigated to evaluate PGMs recovery and grade as responses. The desliming and flotation sensibilities through ANOVA were assessed. Suitable models for predicting the optimum operating conditions, parameter contributions and interactions during PGMs recovery and Design Space were generated. A satisfactory recovery of 79% (17.82 g/ton PGMs) was obtained after the desliming at optimum pH and pulp density of 10.29 and 25.08 Wt.%, while a satisfactory recovery of 39% (45 g/ton PGMs) was obtained after rougher flotation at optimum pH of 9.94 with MIBX, CuSO₄, (NH₄)₂SO₄, mixt depressants of 150.51, 39.697, 60, and 50 g/ton, respectively. Results revealed that RSM through the SSD and the DS play a significant role in monitoring the desliming and flotation process by showing impacting parameters, degree of contribution and correlation within parameters.