铜渣转底炉直接还原回收铁锌工艺研究

为解决国内某铜渣的开发利用问题，以兰炭为还原剂、白云石为添加剂，采用模拟转底炉直接还原-磨矿-磁选工艺，对有价元素铁、锌的回收及杂质硫的脱除进行了研究。结果表明：在兰炭用量为25%，白云石用量为10%，还原温度为1 300 ℃，还原时间为35 min情况下，直接还原过程的锌脱除率为99.14%，可获得ZnO含量为79.59%的氧化锌粉，金属化球团经磨矿、磁选后，获得了铁品位为92.79%、铁回收率为88.12%、硫含量为0.08%的金属铁粉。机理分析表明，铜渣中的铁橄榄石、磁铁矿相大部分已转变为金属铁相，金属铁颗粒明显聚集长大，最大粒度超过100 μm，且与脉石矿物等存在清晰平滑的界面，有利于后续磨矿、磁选工序得到高品位的金属铁粉。

Study on Recovery of Iron and Zinc from Copper Slag by Direct Reduction Process in Rotary Hearth Furnace

In order to solve the problem of development and utilization of a copper slag in China， the recovery of valuable element iron and zinc， and as well as the removal of impurity sulfur were studied by direct reduction-grinding magnetic separation process in simulated rotary hearth furnace with semi-coke as reducing agent and dolomite as additive. The results showed that the removal rate of zinc in direct reduction process was 99.14%， the ZnO content was 79.59% in zinc oxide powder under the conditions of 25% semi-coke， 10% dolomite， 1 300 ℃ reduction temperature and 35 minutes reduction time， and the metallic iron powder with 92.79% iron grade and 0.08% sulfur content was obtained with an iron recovery of 88.12% by grinding and magnetic separation from metallized pellets. The mechanism analysis showed that most of the iron-bearing minerals in copper slag had been transformed into metallic iron phases， which presented obvious aggregation and growth. The maximum metal iron particles could reach more than 100 microns， and there was a clear edge between the iron and gangue minerals， which would be propitious to obtain high-grade metallic iron powder by subsequent grinding and magnetic separation processes.