Title: Copper Slag Processing and Recycling: A Comprehensive Literature Review
Authors: Mutalibkhonov S.S., Khudoymuratov Sh.J., Riskulov D.D.
Volume: 9
Issue: 11
Pages: 23-29
Publication Date: 2025/11/28
Abstract:
- Copper slag is a major byproduct of pyrometallurgical copper smelting, with global production estimated at 45-70 million tons annually. Only about 15% of this waste is currently recycled, while the remainder is stockpiled, posing environmental hazards due to heavy metal leaching and land occupation. This comprehensive literature review synthesizes research published between 2010 and 2025 on copper slag processing, metal recovery technologies, and utilization in construction materials. The review evaluates pyrometallurgical methods such as coal-based direct reduction, reduction-sulfurizing smelting, and emerging hydrogen-based reduction, which achieve iron and copper recovery rates above 90% and 98%, respectively. Hydrometallurgical technologies-including sulfuric acid leaching, high-pressure oxidative leaching, organic acid dissolution, and bioleaching-demonstrate selective recovery of copper, cobalt, zinc, and iron with efficiencies exceeding 75-95% under optimized conditions. Additionally, beneficiation techniques such as flotation, magnetic separation, and gravity separation enable pre-concentration of valuable metals and reduction of residual copper in tailings to below 0.4%. Beyond metal recovery, copper slag utilization in cement, concrete, glass-ceramics, and geopolymer composites offers sustainable material alternatives. Replacing 40-50% of fine aggregates with copper slag in concrete enhances compressive strength by 5-17% and improves durability against carbonation, freeze-thaw cycles, and chloride penetration. Life cycle assessment (LCA) studies reveal that copper slag recycling reduces CO? emissions by 8-37% compared to conventional landfill disposal and virgin material extraction. Furthermore, the economic valuation of metals in historical slag stockpiles highlights significant potential for secondary resource recovery aligned with circular economy principles. This review concludes that integrated processing technologies, standardization of slag-based products, and policy support are essential to fully realize the environmental and economic benefits of copper slag recycling. Future research should focus on low-energy processing, selective recovery of critical metals, and development of high-value engineered materials.