College of Environmental Science and Engineering, Donghua University, Shanghai 201620, PR China.
College of Environmental Science and Engineering, Donghua University, Shanghai 201620, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China.
Sci Total Environ. 2022 Sep 10;838(Pt 3):156453. doi: 10.1016/j.scitotenv.2022.156453. Epub 2022 Jun 2.
Electroplating sludge is a hazardous waste and secondary metal resource because of its heavy metal content, which poses a huge threat to environmental safety if not properly disposed. An innovative process of oxidizing roasting followed by water leaching and smelting reduction to recover Cr, Cu, and Ni from electroplating sludge was proposed in this research, in which other two hazardous wastes of spent cathode carbon combustion dust and copper refining slag were co-treated. The NaF from spent cathode carbon combustion dust could convert CrO to NaCrO using the oxidizing roasting process, resulting in a Cr recovery through the subsequent water leaching. The NaCrO formation was promoted by CaO owing to it transferring the Cr spinel phase of FeCrO [1+] to CaCrO and then to NaCrO. Under optimal conditions, the Cr recovery reached 97.1 %, and most 'F' was solidified into CaF. In the next smelting reduction of the leaching residue, the Cu and Ni were recovered mainly in the form of Cu-Ni alloy. The addition of copper refining slag promoted their recovery, due to it modifying the molten slag and alloy structures and increasing the Cu-Ni alloy separation from molten slag. Some generated high-melting-point Cu-Ni-Fe and Ni-Fe alloys were converted to a Cu-Ni alloy with a low melting point in presence of Co from the copper refining slag, simultaneously with which the Fe was transferred out from Cu-Ni-Fe and Ni-Fe alloys and combined with Co to form a Fe-Co alloy. It increased Cu-Ni alloy droplets aggregation from molten slag and decreased their contents in the residual slag. Under optimized conditions, the Cu and Ni contents in the residual slag decreased to 0.37 and 0.06 wt%, respectively. Besides, the residual slag mainly composed of CaO, CaF and SiO could be used to prepare building materials rendering it harmless.
电镀污泥因其重金属含量而成为危险废物和二次金属资源，如果处理不当，会对环境安全造成巨大威胁。本研究提出了一种从电镀污泥中回收 Cr、Cu 和 Ni 的创新工艺，即氧化焙烧-水浸-熔炼还原，同时处理另外两种危险废物——废阴极碳燃烧灰和铜精炼渣。废阴极碳燃烧灰中的 NaF 可在氧化焙烧过程中将 CrO 转化为 NaCrO，随后通过水浸回收 Cr。CaO 促进了 NaCrO 的形成，因为它将 Cr 尖晶石相的 FeCrO [1+]转化为 CaCrO，然后转化为 NaCrO。在最佳条件下，Cr 的回收率达到 97.1%，大部分“F”被固化为 CaF。在下一个浸出残渣的熔炼还原中，Cu 和 Ni 主要以 Cu-Ni 合金的形式回收。添加铜精炼渣可促进其回收，因为它可以改变熔渣和合金的结构，增加 Cu-Ni 合金与熔渣的分离。一些生成的高熔点 Cu-Ni-Fe 和 Ni-Fe 合金在铜精炼渣中的 Co 存在下转化为低熔点的 Cu-Ni 合金，同时 Fe 从 Cu-Ni-Fe 和 Ni-Fe 合金中转移出来与 Co 结合形成 Fe-Co 合金。它增加了 Cu-Ni 合金液滴从熔渣中的聚集，降低了其在残余渣中的含量。在优化条件下，残余渣中 Cu 和 Ni 的含量分别降低到 0.37 和 0.06wt%。此外，主要由 CaO、CaF 和 SiO 组成的残余渣可用于制备建筑材料，使其无害化。
