Efficient Extraction of Iron and Chromium from Laterite Residue Through Molten Reduction Employing Biomass Reductant

Abstract

With the rapid development of the new energy industry and the stainless steel sector, the demand for nickel has significantly increased, driving substantial advancements in nickel hydrometallurgical technology in recent years. However, the hydrometallurgical process generates a large amount of leaching residue, which contains valuable metals such as iron and chromium. Currently, due to the high processing costs, laterite residue is often directly discarded on land or into the deep sea, which not only causes severe damage to terrestrial and marine ecosystems but also results in the wastage of valuable resources. This study proposes a biomass-based smelting reduction ironmaking technology, utilizing biomass as a reducing agent, aiming to efficiently and sustainably recover iron and chromium from leaching residue. Sawdust, as a biomass resource, is not only cost-effective and abundantly available but also possesses excellent capability for reducing iron oxides, making it an ideal reducing agent. The characterization and microscopic morphology of the products and leaching residue were examined to investigate the phase transformation behavior during the reduction process. The optimal conditions for molten reduction were determined as follows: a mass ratio of sawdust to leaching residue of 0.85, a reduction time of 80 minutes, and a temperature of 1500 ℃. Experimental results showed that under the optimal conditions, the iron and chromium content in the products reached 96.71% and 2.72%, respectively, with recovery rates of 95.80% for iron and 98.56% for chromium.

Keywords: Laterite residue, iron recovery, chromium recovery, biomass reduction, thermodynamic analysis