从不锈钢粉尘中选择性提取Cr、Ni和Zn重金属

基于热力学计算结果,通过配碳还原-熔分工艺,从不锈钢粉尘中选择性分步提取了Cr、Ni和Zn重金属元素.配碳还原实验结果表明,不锈钢粉尘的最佳配碳量为20%,粉尘中Fe、Ni和Zn的最低还原温度为1050℃,Cr的最低还原温度是1 400℃,与热力学计算结果一致,通过控制温度实现了对粉尘中金属的选择性分步还原.直接还原熔分实验说明,Fe-Cr合金最佳熔分温度为1550℃,粉尘中金属以Fe-Ni-Cr合金形式被提取出来,渣金分离状况良好,反应时间5min时金属提取率已达到75%左右,15 min时Fe和Cr收得率达到85%以上,Ni超过90%.通过控制配碳量、还原时间与反应温度,在不改变现有工艺的条件下,不锈钢粉尘直接返回炼钢主流程回收其重金属完全可行.

Selective extraction of heavy metals Cr,Ni and Zn from stainless steel-making dust

Heavy metal elements such as Cr,Ni and Zn were extracted from stainless steel-making dust through the direct reduction and melting process on the basis of thermodynamic analysis.Carbon deoxidization experiment results show that the optimal carbon addition percentage in the dust is 20%,and the lowest reduction temperature is 1 050 ℃ for Fe,Ni and Zn and 1 400 ℃ for Cr,which are in agreement with the thermodynamic calculation results.These metals can be selectively reduced through controlling the temperature.According to direct reduction and melting experiment results,the optimal melting temperature of the Fe-Cr alloy is 1 550 ℃,metals in the dust are extracted as the Fe-Ni-Cr alloy,and the slag is separated from the metals quite well.The metal extraction rate is about 75% after 5 min reaction;but after 15 min reaction the Fe and Cr extraction rates surpass 85%,while the Ni extraction rate is over 90%.These experimental results indicate that it is completely feasible to return the stainless steel-making dust to the steel-making main flow and recycle its heavy metals by controlling the carbon content,reduction time and temperature without modifying the present process.