Utilization of uncarbonized palm kernel shell (PKS) in ilmenite (FeTiO₃) carbothermic reduction process

Biomass as a green reducing agent in the carbothermic reduction process is still a developing and research-worthy area. Low carbon content and the rapid decomposition rate of biomass at high temperatures are considered and disadvantages of fresh biomass as a reducing agent. However, the volatile matter and tar content from fresh biomass has the potential to be a reducing agent. In this study, carbothermic reduction of ilmenite (FeTiO3) has been carried out with an activated Palm Kernel Shell (PKS) as a reducing agent and the process was carried out simultaneously, using uncarbonized PKS. Treatment of ilmenite calcination and chemical activation of PKS was carried out in this study. The result show that the calcination of ilmenite and chemical activation of uncarbonized PKS effectively increased the surface area and porosity sufficiently to increase the contact zone during reduction. Chemical activation with phosphoric acid in an attempt to hydrolyze short-chain polymers and monomers in PKS resulted in the loss of the diffraction pattern of the sucrose phase. During the activation process, cross-linking reaction between phosphate ion and lignocellulose was occurred. Cross-linking reaction converted PKS to be more stable at high temperature. The FTIR results also show the same thing, specifically a decrease in the intensity of the hydroxyl group (-OH) at wave numbers 3000-3400 cm-1, which indicates the loss of combined water and volatile matter of calcined ilmenite and activates PKS. Based on XRD data, calcination of ilmenite resulted in the loss of the goethite phase and increased the ilmenite phase significantly. The loss of the goethite phase and sucrose was reported to have a good effect, specifically an increase in porosity due to the release of combined water and volatile matter. The highest metallic iron content and degree of metallization, precisely 15.5% and 51.5%, were obtained at a temperature of 1200°C with a holding time of 1 hour and a stoichiometric amount of activated PKS. The insignificant difference in the percentage of total Fe in raw ilmenite, which is 26.1%, with total Fe in the reduced composite shows that the carbothermic reduction using uncarbonized PKS succeeded in separating Fe into the form of iron oxide from the Fe mineral complex in ilmenite.