A novel method for effective solidifying chromium and preparing crude stainless steel from multi-metallic electroplating sludge

Wang Heng; Yu Yong; Hu Jianhang; Wang Hua

doi:10.1016/j.jhazmat.2023.133068

A novel method for effective solidifying chromium and preparing crude stainless steel from multi-metallic electroplating sludge

J Hazard Mater. 2024 Mar 5:465:133068. doi: 10.1016/j.jhazmat.2023.133068. Epub 2023 Nov 24.

Authors

Wang Heng¹, Yu Yong², Hu Jianhang¹, Wang Hua¹

Affiliations

¹ Engineering Research Center of Metallurgical Energy Conservation and Emission Reduction, Ministry of Education, Kunming University of Science and Technology, Kunming, China; State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, China; National Local Joint Engineering Research Center of Energy Saving and Environmental Protection Technology in Metallurgy and Chemical Engineering Industry, Kunming University of Science and Technology, Kunming, China; Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, China.
² Engineering Research Center of Metallurgical Energy Conservation and Emission Reduction, Ministry of Education, Kunming University of Science and Technology, Kunming, China; State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, China; National Local Joint Engineering Research Center of Energy Saving and Environmental Protection Technology in Metallurgy and Chemical Engineering Industry, Kunming University of Science and Technology, Kunming, China; Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, China. Electronic address: yuranrui45@163.com.

PMID: 38043422
DOI: 10.1016/j.jhazmat.2023.133068

Abstract

Electroplating sludge (ES) is a globally prevalent hazardous waste that primarily contains Cr, Cu, Ni, and Fe. However, the residual Cr phases within the slag potentially poses an environmental risk in current vitrification. A novel method for effective recovering and solidifying Cr in ES is proposed in this work. ES was desulfurized and subsequently co-treated with ferrosilicon (Fe-Si) and spent carbon anode (SCA) for enhancing the recovery of Cr, Cu, Ni, and Fe to prepare crude stainless steel. Under optimal conditions, the recovery ratios of Cr, Cu, Ni, and Fe reached 96.96%, 99.45%, 99.92%, and 99.20%, respectively, signifying improvements of 21.4%, 0.2%, 1.5%, and 2.8%, respectively, compared with existing research. Meanwhile, the fluoride in SCA yielded CaF₂, further progressing to the Si-Ca-F-Na-Al-O phase, with a solidification ratio of 97.87%. The Cr leaching content of the residual Cr-Cu-S phase in the slag remained below 5 mg/L across a pH range of 2-4, demonstrating enhanced stability compared to prior alloy, oxide, and chemically dissolved phases. An innovative approach for solidify Cr by forming matte holds implications for the treatment of Cr-containing solid wastes such as chromium slag, tannery sludge and stainless steel slag.

Keywords: Co-treatment; Cr efficient solidification; Cr, Cu, Ni, and F transformation behaviors; Electroplating sludge; Slag toxic leaching mechanism.