铜渣碳热还原提铁研究及尾渣资源化应用分析

Research on Iron Recovery from Copper Slag by Carbothermic Reduction and Resource Utilization of Residual Slag

摘要: 以某铜冶炼厂炼铜尾渣为原料，采用高温碳热还原工艺开展提铁试验研究，重点考察碳粉用量、CaO与CaF₂助熔剂、还原温度与时间对铜渣提铁率、金属铁品位及渣–铁分离效果的影响规律，并对还原尾渣的物化特性与资源化利用潜力进行了分析。结果表明：碳用量过低会导致还原不充分，过量则易造成金属铁弥散析出；额外添加CaO对提铁效果提升有限，额外添加CaF₂可改善熔体流动性，明显提升提铁率，提高铜渣碳热还原温度(1380℃至1460℃)可显著强化还原与分离过程。在碳用量12%、添加10% CaO与10% CaF₂、1420℃保温80 min的条件下，提铁率达到89.73%，金属铁品位87.72%，尾渣全铁含量降至5.61%。该条件下金属铁呈致密块状聚集、渣–铁界面清晰，尾渣以均匀硅酸盐玻璃体为主，化学成分与发泡陶瓷、水泥及微晶玻璃等硅酸盐材料体系具有一定相似性，表现出潜在资源化利用价值。

Abstract: Using copper smelting tailing slag from a copper smelter as raw material, experimental investigations on iron recovery were conducted through a high-temperature carbothermic reduction process. The effects of carbon dosage, CaO and CaF₂ flux additions, reduction temperature, and holding time on the iron recovery rate, metallic iron grade, and slag-iron separation behavior were systematically examined. In addition, the physicochemical properties and potential resource utilization of the reduced slag were analyzed. The results indicate that insufficient carbon addition leads to incomplete reduction, whereas excessive carbon promotes the dispersed precipitation of metallic iron. Additional CaO showed limited improvement in iron recovery performance, while CaF₂ addition effectively enhanced melt fluidity and significantly increased the iron recovery rate. Increasing the carbothermic reduction temperature of copper slag from 1380˚C to 1460˚C markedly promoted both the reduction reaction and slag-iron separation process. Under the optimum conditions of 12 wt% carbon addition, 10 wt% CaO, 10 wt% CaF₂, and holding at 1420˚C for 80 min, the iron recovery rate reached 89.73%, the metallic iron grade reached 87.72%, and the total iron content in the residual slag decreased to 5.61%. Under these conditions, metallic iron aggregated into dense bulk phases with a distinct slag-iron interface, while the residual slag mainly consisted of a homogeneous silicate glass matrix. Its chemical composition exhibited certain similarities to silicate material systems such as foamed ceramics, cement, and glass-ceramics, demonstrating potential value for resource utilization.