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Volume 13
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10.3390/pr13123935
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Article

A Sustainable Strategy for Co-Melting of Electroplating Sludge and Coal Gasification Slag: Metals Recovery and Vitrified Product Valorization

by
Wei Leng
1,
Nengwu Zhu
1,2,3,4,*,
Fei Li
1,
Xiaorong Wei
1,
Sihai Zhang
1,*,
Wanqi Li
1 and
Pingxiao Wu
1,2
1
School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
2
The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Cluster Ministry of Education, Guangzhou 510006, China
3
Guangdong Environmental Protection Key Laboratory of Solid Waste Treatment and Recycling, Guangzhou 510006, China
4
Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, Guangzhou 510006, China
*
Authors to whom correspondence should be addressed.
Processes 2025, 13(12), 3935; https://doi.org/10.3390/pr13123935
Submission received: 28 October 2025 / Revised: 16 November 2025 / Accepted: 2 December 2025 / Published: 5 December 2025
(This article belongs to the Topic New Research on Waste Treatment, Disposal and Valorization)
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Abstract

The high concentrations of heavy metals in electroplating sludge (ES) result in its dual properties as both hazardous waste and a potential secondary resource. Effective strategies are urgently needed for the simultaneous detoxification and utilization of ES. In this study, a sustainable strategy for co-melting of ES and coal gasification slag (CGS) was proposed. By optimizing the mass ratio of ES to CGS (m(ES)/m(CGS) = 1) and adding 7.5 wt% B2O3, a low-temperature vitrification system was established at 1250 °C, enabling the recovery of 97.31 ± 0.61% Cu, 99.17 ± 0.43% Ni, and 81.84 ± 0.33% Fe in the alloy phase within 90 min. Melt structure analysis indicated that CaO and [BO3] promoted the depolymerization of the silicate network, facilitating the amorphous phase transition and enhancing fluidity. Meanwhile, residual carbon from CGS functioned as a reductant, reducing metal minerals in the mixture to form alloys that were simultaneously separated during co-melting. Compared with the raw sample, heavy metals in the vitrified product were effectively immobilized, exhibiting low risk of heavy metal leaching. Furthermore, high-value-added glass-ceramic materials were successfully prepared from the vitrified product. Therefore, the proposed strategy could serve as a sustainable solution for the treatment of ES and CGS.
Keywords: electroplating sludge; coal gasification slag; co-melting; silicate network depolymerization; metals recovery; vitrified product electroplating sludge; coal gasification slag; co-melting; silicate network depolymerization; metals recovery; vitrified product
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MDPI and ACS Style

Leng, W.; Zhu, N.; Li, F.; Wei, X.; Zhang, S.; Li, W.; Wu, P. A Sustainable Strategy for Co-Melting of Electroplating Sludge and Coal Gasification Slag: Metals Recovery and Vitrified Product Valorization. Processes 2025, 13, 3935. https://doi.org/10.3390/pr13123935

AMA Style

Leng W, Zhu N, Li F, Wei X, Zhang S, Li W, Wu P. A Sustainable Strategy for Co-Melting of Electroplating Sludge and Coal Gasification Slag: Metals Recovery and Vitrified Product Valorization. Processes. 2025; 13(12):3935. https://doi.org/10.3390/pr13123935

Chicago/Turabian Style

Leng, Wei, Nengwu Zhu, Fei Li, Xiaorong Wei, Sihai Zhang, Wanqi Li, and Pingxiao Wu. 2025. "A Sustainable Strategy for Co-Melting of Electroplating Sludge and Coal Gasification Slag: Metals Recovery and Vitrified Product Valorization" Processes 13, no. 12: 3935. https://doi.org/10.3390/pr13123935

APA Style

Leng, W., Zhu, N., Li, F., Wei, X., Zhang, S., Li, W., & Wu, P. (2025). A Sustainable Strategy for Co-Melting of Electroplating Sludge and Coal Gasification Slag: Metals Recovery and Vitrified Product Valorization. Processes, 13(12), 3935. https://doi.org/10.3390/pr13123935

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