Smelting operations across Africa are among the most energy-intensive industrial processes, consuming vast amounts of electricity and fuel to extract metals from ore. Yet, a large portion of this energy is lost as waste heat through furnace off-gases, hot slags, and cooling circuits. Harnessing this thermal energy through Energy Recovery Systems (ERS) presents an opportunity for mining companies to reduce operational costs, improve efficiency, and decrease carbon emissions, all while supporting sustainable industrial and Environmental practices.
Pioneering Examples Across the Continent
Several African mines already demonstrate the benefits of ERS. In Zambia, First Quantum Minerals’ Kansanshi copper mine has implemented an off-gas recovery system in its smelter through a sulphuric acid plant. By capturing high-temperature off-gases, the system converts them into sulphuric acid while simultaneously reducing emissions. This demonstrates how energy that would otherwise be wasted can be repurposed, creating both environmental and economic value.
Similarly, Zimbabwe has explored ERS in platinum processing. Researchers designed a system to capture heat from smelter off gases, producing approximately 1.03 MW of electricity and improving furnace efficiency by 8.5%. While still at the design stage, this project illustrates the technical feasibility and potential benefits of retrofitting mid-sized smelting operations with ERS technology. Collectively, these examples show that energy recovery is spreading across Africa, beyond the traditional South African focus.
Heat Recovery in Southern Africa’s Smelters
Southern Africa’s ferroalloy and base-metal smelters also highlight ERS potential. Studies indicate that 25–75% of heat from smelting and heating processes can be recovered, particularly from off-gases and high-temperature slags ranging between 1,200 °C and 1,800 °C. Technologies such as waste heat boilers, steam turbines, Organic Rankine Cycle (ORC) systems, and slag heat recovery units convert thermal energy into electricity or pre-heated feed materials. For older plants, retrofitting these technologies significantly improves efficiency without replacing entire smelters.
Pre-Heating and Process Integration
ERS can also be integrated into broader process improvements. By using recovered heat to pre-heat ore or feedstock, smelters can reduce the energy required in the furnace itself. Companies like Metso Outotec have demonstrated pre-heating solutions in African plants, saving tens of kilowatt-hours per tonne of metal produced. Retrofitting existing plants with pre-heating systems or integrating recovered heat into existing workflows allows mines to improve efficiency while leveraging their current equipment base.
Overcoming Retrofitting Challenges
While ERS offers clear benefits, retrofitting older smelters comes with technical challenges. Integrating waste-heat boilers, turbines, or ORC systems into existing plant layouts requires careful engineering to avoid disrupting production. Skilled personnel must be trained to operate and maintain new systems, and careful planning is essential to optimize the flow of recovered heat through the plant. However, the long-term benefits reduced energy consumption, lower emissions, and improved process efficiency make these retrofits a worthwhile investment for forward looking mines.
Energy Recovery Systems represent a big opportunity for African smelting operations. From Zambia to Zimbabwe and across Southern Africa, ERS can capture thermal energy lost in furnaces, off-gases, and slags, converting it into electricity, pre-heating feedstock, or industrial products like sulphuric acid. In addition to improving efficiency, ERS enhances environmental sustainability by reducing greenhouse gas emissions, lowering harmful off-gas pollutants, and enabling real-time monitoring of gas composition and temperature to ensure compliance and optimize operations. For mining companies, retrofitting older plants with ERS not only reduces costs but also reinforces sustainability commitments.
Read More About Mining systems HERE
