Resource utilization of agricultural waste straw a new metho 2027 Minerals

The efficient and environmentally friendly utilization of low grade boron-bearing iron concentrate resources remains challenging due to the complex mineral composition and strong association between boron and iron minerals, coupled with high energy consumption and environmental impacts associated with conventional coal-based reduction processes. This study aims to explore the potential of corn straw as a biomass-derived reductant to replace conventional coal powder for the high temperature reduction and magnetic separation of boron-bearing iron concentrate. The pyrolysis characteristics of corn straw and its reduction behavior were investigated, followed by electric furnace reduction and magnetic separation experiments. The effects of reduction temperature, reduction time, and C/O molar ratio on iron metallization and boron iron separation were systematically evaluated. Characterization of the reduction products was conducted using ICP-AES, XRF, XRD, and SEM to elucidate the reduction and separation mechanisms. The results indicate that corn straw undergoes pyrolysis to generate H2, CO, and biochar, forming a gas-solid composite reduction system conducive to the conversion of iron oxides to metallic iron. Under optimal conditions of 1300 °C, a C/O molar ratio of 1.2, and a reduction time of 30 minutes, the iron metallization ratio achieved 91.47%, with an iron concentrate exhibiting an iron grade of 87.9% after magnetic separation.