Operating zone identification of an auxiliary electrode electr 2027 Minerals

Ilmenite recovery from heavy mineral sand processing rejects was investigated using an auxiliary electrode electrostatic roll separator (AEERS). The AEERS incorporates an independently positioned lower electrode beneath the grounded rotating drum, which is intended to extend electric field control into the particle discharge region relative to a conventional high-tension roll separator. A representative reject sample containing 11.97% ilmenite and 66.20% garnet, along with minor amounts of rutile, zircon, and sillimanite, was characterized and used as feed. A six-factor Central Composite Design (CCD) comprising 30 experimental runs was employed to evaluate the effects of feed rate, feed-roll speed, separation-roll speed, feed temperature, splitter position, and applied voltage on ilmenite recovery. A quadratic response surface methodology (RSM) model was developed and validated by analysis of variance (ANOVA), leading to a statistically significant model (F = 58.19, p < 0.00001, R2 = 0.9987). The maximum ilmenite recovery of 52.3% at a concentrate grade of 90.4% was achieved under specific operating conditions. Further analysis using decision tree regression and SHapley Additive exPlanations (SHAP) helped in classifying the operating space into zones and identifying the contributing variables impacting the recovery process.