Waste not, want not – using aluminium waste to create cement
Rio Tinto have partnered with leading sustainable construction materials company Lafarge Canada to create a cement product using waste from aluminium smelting.
Known as Alextra, it’s made from waste – from used potlining (an essential part of the electrolysis process, whereby alumina is turned into into aluminium) and uses less non-renewable resources, helping to reduce landfill and meet sustainability goals – it is also cheaper than other materials.
For the electrolysis process to work, potlining must be replaced every 5-8 years. The old lining contains hazardous materials, which requires careful handling.
In 2008, a treatment plant capable of removing the hazardous substances from used potling, rendering it safe, was established in Quebec, Canada. Currently all potlining waste from the Quebec treatment plant is treated to make it safe, and approximately 80% is recycled into new products. One of these new products in cement. It is anticipated that Lafarge Canada will make approximately one million tonnes of cement using Alextra.