China Nonferrous Metallurgy

Lead and zinc oxide slag with high zinc content was synthesized at high temperature using high lead slag as raw material, and anthracite was added as reducing agent for direct reduction experiment. The experiment studied the effects of reducing coal amount, reducing temperature, reducing time, Fe/SiO₂, CaO/SiO₂ on the recovery rates of Pb, Zn, and Cu in lead and zinc oxide slag. The experimental results showed that the recovery rates of Pb, Zn, and Cu of lead and zinc oxide slag increased with the increase of reduction coal amount, reduction temperature, and reduction time. However, excessive coal ratio and reduction temperature are not conducive to the improvement of Pb and Cu recovery rates; The recovery rates of Pb, Zn, and Cu of lead and zinc oxide slag increased with the increase of Fe/SiO₂ and CaO/SiO₂. However, as Fe/SiO₂ increased to 0.78 and CaO/SiO₂ increased to 0.8, continuing to increase Fe/SiO₂ and CaO/SiO₂ would reduce the recovery rates of Pb, Zn, and Cu. The suitable conditions for the reduction of lead and zinc oxide slag were: coal ratio of 1.2~1.4, reduction temperature of 1623~1673K, reduction time of 90~120minutes, Fe/SiO₂=0.78~1.17, CaO/SiO₂=0.5~0.8. Under the above process conditions, the recovery rates of Pb, Zn, and Cu in lead and zinc oxide slag could reach 84.01%, 94.51%, and 85.8%, respectively.