Optimizing the pathways of industrial solid waste recycling under multiple perspectives: a case study of copper smelting slag

To mitigate the environmental and climate impacts of industrial solid waste management and disposal processes, and to enhance recycling efficiency, this study developed a multidimensional optimization method for the recycling of industrial waste. The method integrated three indicators: environmental-resource interaction attribute, life cycle assessment, and economic resource value assessment. The findings indicated that compared to landfill methods, recycling pathways through upcycling and downcycling of industrial solid waste significantly reduced ecotoxicity and human health toxicity by 96.86% and 98.53%, respectively. The method can also diminish soil pollution and preserve soil ecological health. It was anticipated that by 2035, the proportions of upcycling, downcycling, and reuse of copper smelting slag would reach 30%, 50%, and 10%, respectively, achieving optimal target values. However, an increased proportion of upcycling would lead to higher carbon emissions and reduced overall benefits. Based on these results, downcycling could process a large volume of industrial solid waste in the short term but was constrained by the construction industry and product quality management. Therefore, long-term planning requires rationally allocating the proportions of industrial solid waste recycling pathways to maximize environmental and economic benefits.