Application of Response Surface Methodology on the Optimization of Chromite Recovery from the South African Middle Group Chromite Seams

Abstract

The aim of this study was to optimize the recovery of chromite from the chrome plant tailings of the South African Middle Group chromite seams using a Wilfley shaking table. The optimization process employed the response surface methodology in conjunction with the central composite design. The independent variables considered in the investigation included the tilt angle (°), sample feed rate (g/min), table vibration (Hz), water flow rate (L/H), and particle size range (µm). On the other hand, the recovery (%), grade (% Cr₂O₃), Cr/Fe ratio, and separation efficiency (SE) (%) were determined as the response variables. Based on the characterization results, the sample was identified as a low-grade chromite containing 19.86% Cr₂O₃ and 18.12% Fe₂O₃ with a Cr/Fe ratio of 1.07. The bulk gangue material was well-liberated and rich in MgO (10.45%), Al₂O₃ (12.10%), and SiO₂ (33.70%). The particle size distribution of the sample was 80% passing 106 µm. The optimal values for recovery, grade, Cr/Fe ratio and SE were found to be 71.59%, 36.97% Cr₂O₃, 1.52 and 30% respectively. The corresponding operating conditions were a tilt angle of 5.88°, a sample feed rate of 175 g/min, a table vibration of 44.5 Hz, a water flow rate of 366.16 L/H, and a particle size range of − 106 + 53 µm.

Graphical Abstract