分段还原—磁选法回收赤泥中的铁

以拜耳法赤泥为原料,首先采用氢气预还原,再配碳进行二次还原,最后磁选。探究了还原过程中氢气流速、还原温度、配碳量、保温时间等因素对还原铁粉回收率和品位的影响。结果表明,在赤泥与碳酸钠质量比为100∶5、氢气流速2600 mL/min、温度1000℃、保温时间120 min、碳粉与一次还原后的赤泥质量比为1∶5的条件下,可得到品位为93.19%、回收率为79.53%的还原铁粉。产品可直接用于粉末冶金领域及钛白粉行业。微观分析表明,气固反应和固固反应相结合更容易加深Fe₂O₃向Fe的转变程度,以碳酸钠为添加剂可以提高还原反应的效果。

Iron Recovery from Red Mud by Multiple-Reduction Magnetic Separation Method

Bayer process red mud was adopted as raw material,with process as follow:firstly hydrogen prereduction,then carbon secondary reduction,and finally magnetic separation,the experiment explored the impact of hydrogen flow rate,reduction temperature,carbon amount,soaking time and other factors on the recovery rate and grade of reduced iron powder.Results show that reduced iron powder grade of 93.19%and recovery of 79.53%at mass ratio of red mud to sodium carbonate was 100∶5,hydrogen flow rate of 2600 mL/min,reduction temperature of 1000℃,soaking time of 120 min,mass ratio of carbon powder to red mud after primary reduction was 1∶5.The resulting products can be used directly for powder metallurgy field and titanium dioxide industry.Microscopic analysis showed that the combination of gas-solid reaction and solid-solid reaction was easier to deepen the transition degree of Fe₂O₃ to Fe,and sodium carbonate was used as an additive could improve the effect of the reduction reaction.