Implications of renewable energy sources in metallurgy: Utilization of concentrated solar energy in recycling metallurgical wastes

Abstract

Solar energy, when it is concentrated, can reach temperatures as high as 3000 °C and generate heat without producing pollutants such as carbon dioxide or other harmful agents. Additionally, solar energy is virtually free and can be utilized in remote areas not connected to the electrical grid. However, slags, a by-product of metallurgical industries, are not commonly used due to the cost of processing them. This manuscript proposes studying the use of concentrated solar energy to extract metals from four types of slags: basic oxygen furnace (BOF) slag, copper slag, silicomanganese slag, and ferromanganese slag, each containing important metals. Experimental work at the Odeillo solar furnace suggests that iron oxides in the BOF slag transform into magnetic phases, while copper slag experiences changes in fayalite (that partially transforms into magnetite) and copper oxides and sulfides (that also convert into metallic copper nodules). The ferromanganese and silicomanganese slags become more refractory, making the extraction of manganese more challenging. Overall, the study suggests that at least part of the metals might be collected in a usable form.