Effect of Temperature in Carbothermic Reduction of Indonesian Limonite Ore Using Printed Circuit Boards as Reducing Agent

Abstract

In recent years, there have been increases in the production of electronic waste, such as Printed Circuit Board (PCB), because of the rapid advancement of technology. PCBs are highly valuable, as they contain metals such as copper, silver, and gold. This research aims to investigate the feasibility of using PCB, discarded from laptops as the reducing agent for the carbothermic reduction process of Indonesian limonite ore and the effect of temperature on the carbothermic reduction process, specifically on the phase transformation and the differences in microstructure. Based on the TGA-DSC result, the mixture of limonite and PCB have three endothermic peaks at 90 °C, 290 °C, 450 °C and one exothermic peak at 910 °C, whereas the mixture of limonite and coal has the same trends but the exothermic peak occurs at 1070 °C. To investigate the effect of PCB powder on the reduction of limonite ore, a carbothermic reduction experiment was carried out through the mixing of 8.0 g of limonite ore with 2.0 g of PCB powder (20 wt.%), which was then further compacted. The experiment was carried out at temperature variations of 700 °C, 900 °C, 1100 °C for 1 hour in an inert atmosphere furnace. The products of the reduction process were magnetically separated and then characterized using SEM/EDS and XRD to evaluate the differences in microstructure. This research found that PCB powder is a feasible reducing agent for the reduction of limonite ore.