Refining an ancient art
Extracting metals from ore was one of the most profound advances prehistoric humans made in their evolution out of the Stone Age. Most metals naturally occur in mineral form and require smelting, a multistage process that involves oxidising and reducing chemical reactions at high temperatures, to extract the metal from its mineral ore.
Traditional smelting techniques are both energy and carbon intensive. Coking coal is often used to fuel the high temperatures and act as a chemical reducing agent, removing oxygen from the ore to leave the metal.
In an increasingly carbon constrained world, refinements to smelting methods that reduce carbon emissions are crucial for ongoing commercial and environmental viability of pure metal production and extraction.
Energy efficient smelting
We developed SiroSmelt, a high-intensity smelting process that uses a combustion lance submerged into the furnace chamber to provide efficient heat transfer and mixing in the molten ore bath.
SiroSmelt technology achieves very good environmental performance due to the relatively simple furnace geometry and small size of the reactor with very efficient sealing against fugitive emissions.
First developed in the early 1970s, SiroSmelt is now the basis of the most efficient and environmentally sensitive metal smelting technology in the world.
While it has been primarily used to increase the efficiency of lead and copper smelting from concentrates, it has also been adapted for nickel, zinc residues, iron and tin production and for unconventional processes such as recycling scrap metal, e-waste, lead batteries and waste processing.
SiroSmelt technology is used in over 70 metallurgical smelting plants around the world and has been successfully used for a wide variety of base metals smelting, for waste-treatment and for direct iron production (on the pilot scale).
The process is licensed to Glencore Technology, which markets it as Isasmelt, and to Finnish company Outotec as Ausmelt.
Glencore Technology and Outotec have taken SiroSmelt to the world. Outotec's expertise lies not just with copper and lead smelting but with a range of other metals. It has taken the technology to nickel smelting, zinc plants and tin smelters and has a major nickel- copper matte converting hub run by Anglo Platinum in South Africa, which concentrates platinum group metals for further hydrometallurgical recovery.