中国有色冶金

The stockpile of red mud in China has exceeded 1 billion tons, and the main type of red mud is Bayer method red mud, which contains iron up to 30% or more, and is an iron resource with high economic value. The current method of recovering iron resources in red mud is mainly high-temperature reduction roasting-magnetic separation, with solid carbon-based reductant and gas-based reductant as the main reductant, which requires a large amount of energy consumption and cost. China is a large agricultural country, the annual output of the main crop residues is 700 million t. These biomasses have the advantages of carbon neutrality, high reactivity, low ash content, high storage capacity, renewable, etc., and the pyrolysis temperature is much lower than the solid carbonaceous reductant, and the temperature of its reduction of trivalent iron is only 300~800℃, which belongs to the low-temperature pyrolysis, so that the use of biomass reduction roasting of red mud can greatly reduce the energy consumption and cost. This paper focuses on the comparison of the parameters of trivalent iron reduction by solid carbonaceous reductant, gas-based reductant and biomass reductant, and elaborates in detail the pyrolysis process of biomass and the mechanism of reducing Fe₂O₃ in red mud, and concludes that the biomass reduction roasting-magnetic separation technology can realize the reduction and high-value utilization of solid wastes, such as red mud and agricultural straw, and has very high economic value and environmental benefits. Finally, the following suggestions are made for the future study of iron resource recovery in red mud: to strengthen the exploration of technology coupling to achieve the industrialized disposal of red mud; to recycle the gas and heat produced by the pyrolysis of biomass; to explore the ways to comprehensively utilize the tailing slag; and to enhance the research on the separation of iron and aluminum minerals in order to achieve the continuous and dynamic production of iron ore concentrates.