Effect of sulfur and sodium sulfate on phase transformation and microstructure on carbothermic reduction of Indonesian ilmenite

Utilization of ilmenite and pulverized biomass of palm kernel shell is a beneficial solution to deal with the depletion of high-grade titanium minerals and manage of palm oil waste. The purposes of this research are to analysis the phase transformation and microstructure with additive addition. Sulfur and sodium sulfate have used an additive with an additional dosage of 0%, 1.5%, 3.0%, and 4.5%, and the reductant was the pulverized palm kernel shell biomass. The ilmenite concentrate was reduced at 1200 °C for 60 minutes in inert condition (N₂ atmosphere). Testing methods performed are Optical microscope (OM), X-Ray diffraction (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), and Energy Dispersive X-ray spectroscopy (EDX), calculating of the average particle size, and metal recovery. The results showed that the active additive used was sodium sulfate compared to sulfur. At the addition of 4.5 wt.% sodium sulfate, it was obtained phases of titanium suboxide, Ti₆O₁₁ and Ti₃O₅, with very high intensity. Recovery and grades of the reduced sample with 4.5 wt.% sodium sulfate are reached 70.91% and 94.20% Fe, respectively. Moreover, the average particle size of metallic iron increased from 11.96 μm to 38.36 μm with the addition of 4.5wt.% sodium sulfate.