KU Leuven researchers, together with members of Aurubis AG, critically reviewed the topic of sustainable and comprehensive utilisation of copper slag. The paper was published in the Journal of Sustainable Metallurgy. The findings show that considering the multiple options for the application of copper slag, proven examples of copper slag being in use today and wide possibilities of slag cleaning recycling and utilisation of copper slag worldwide can be increased, if politics, society, industry, and science pull together.
Origin and Application of Copper Slag
Annually more than 45 Mt of copper slag is produced worldwide from pyrometallurgical smelting and refining of copper sulphide ores. During the copper production process, iron and sulphur are oxidised, and silica (SiO2) is added to form a liquid ferric or ferrous silicate slag.
Only 15% of the slag from copper production worldwide is used as a product, whereas the rest is landfilled, although copper slag is a valuable resource of minerals and metals. The slag still contains both valuable and hazardous metals, which are chemically dissolved in the slag or entrained as metal or matte particles. Typically, treatment processes are applied to recover or remove these elements from the slag.
Prospect of Increased Copper Slag Utilisation
The valuable aspect of the study is that the issues of copper slag treatment and utilisation are viewed from many perspectives. Potential slag treatment routes are proposed, where their benefits and drawbacks with respect to ecologic, operational, and economic aspects are discussed.
It was found that slag treatment processes that have been investigated show the potential to increase the metal recovery compared to conventional industrially-applied processes such as slag settling and flotation. Recently the understanding of the elution behavior of copper slag and the utilisation of Cu slag as supplementary cementitious material was improved. Additionally, several ways of utilising slag are already demonstrated in industrial practice. Therefore, the authors conclude that metal recovery from copper slag and valorisatin of copper slag as sustainable aggregate can be increased.
Full reference of the paper
Eric Klaffenbach, Victor Montenegro, Muxing Guo, Bart Blanpain (2023), Sustainable and Comprehensive Utilization of Copper Slag: A Review and Critical Analysis, Journal of Sustainable Metallurgy, https://doi.org/10.1007/s40831-023-00683-4