Rapid and direct magnetization of goethite ore roasted by biomass fuel

Biomass is a renewable and carbon neutral solid fuel. Utilization of biomass in iron ore roasting process as heating agent and reducing agent contributes to energy conservation and emission reduction, and can partially replace for coal and coke. The biomass instead of coke was mixed together with iron ore powder from the north of Hainan province into ball roasting process to investigate the effects of mixture composition, reduction temperature, reaction time, the thermal reduction and magnetic properties of the mixture. The results show that the reduction temperature, reaction time and dosage of the biomass are correlated to the quality of the reduction and the magnetism of the iron ore, within the experimental conditions. The mechanism of the biomass reducing the weakly magnetic goethite into stronger magnetic iron oxide has been discussed. The results show that the goethite ores is dramatically reduced and magnetized by about 20 wt.% biomass at low roasting temperature. Application of biomass energy in iron ores roasting process is prospective to the effective use of biomass and for decreasing the consumption of fossil fuels in the steelmaking process.

► A novel direct reduction technology using biomass in goethite ores is presented.
► The effect reducing temperature is less than 650 °C.
► Goethite ore is directed reduced by biomass and converted into maghemite.
► The magnetization of product shows 96% ferromagnetic, Ms of 25.9 emu/g.
► The magnetic susceptibility of product is enhanced more than 30 times.