Effect of Biochar as Reductant on Magnetizing-roasting Behavior of Pyrite Cinder

The effect of biochar substituted for anthracite as reductant on magnetizing-roasting pyrite cinder was investigated. The key of magnetizing-roasting is the gasification reaction between reductants and CO2. Since biochar could react with CO2 more rapidly at lower temperature, the reactivity of biochar is better than that of anthracite. The gasification of biochar could produce reducing condition of φCO / (φCO + φCO2) about 10% – 20% between 700–800 °C, which is in accord with the atmosphere and temperature of Fe2O3 reduction. So it is beneficial to the reduction of iron mineral of pyrite cinder. Compared with anthracite, biochar could decrease the roasting temperature from 825 to 750 °C and roasting time from 20 to 15 min, which shows that a better effect of magnetization could be obtained in the condition of lower temperature and shorter time. Using biochar as reductant, iron concentrate extracted from pyrite cinder as about 61% iron grade could be produced, and the recovery is over 90% under the condition of above 90% grinding particle less than 0.045 mm and magnetic intensity of 0.121–0.194 T.