Reduction roasting of lead-zinc-containing refractory hematite and limonite and evolution process of lead and zinc impurities synchronously

Magnetization reduction and roasting-weak magnetic separation is an effective method to treat refractory hematite and limonite, while lead and zinc are harmful impurities in blast furnace ironmaking, which can seriously affect the production of blast furnace.Aiming at the refractory hematite and limonite containing 0.39% lead, 0.30% zinc and 47.04% total iron(TFe), the mineral characteristics of lead-zinc impurities and the production characteristics of hematite and limonite are investigated by chemical analysis, rock-mineral determination and reduction roasting.Reduction roasting of lead-zinc-containing refractory hematite and limonite and evolution process of lead and zinc impurities synchronously is also discussed.The results show that hematite is 42.97% and magnetic iron is only 1.89%, lead oxide and plumbojarosite are 90.3% of lead impurities, and zinc oxide is 90.6% of zinc impurities.Microscopic characteristics show that there are three processes in the reduction process of hematite and limonite:magnetization roasting, fused body and deep reduction.Lead and zinc impurity minerals can be found in the magnetization roasting and fused body temperature range of iron ore, but lead and zinc impurity minerals cannot be found in the deep reduction stage.When reduction roasting temperature is 1 200 ℃, reducing agent C∶O=2.25 and roasting time is 60 min, the iron grade of weak magnetic separation concentrate is 89.63%, the recovery rate is 86.09%, and the removal rates of harmful elements Pb and Zn are 98.97% and 91.19%, which provides a new way for the separation and processing of this kind of iron ore and the removal of impurities of lead and zinc synchronously.