Development of a novel process for recovering fluoride from spent pot-lining as AIF2(OH) using industrial waste solutions (2010–2013)
Every 6-7 years the carbon cathode lining of Al smelting pots needs to be replaced which gives rise to a hazardous waste known as spent pot-lining (SPL) containing significant levels of leachable fluoride and cyanide. With no accepted treatment technology, SPL is currently stockpiled under controlled conditions. This project aims to develop a process that recovers the fluoride as AIF20H which can then be converted to AIF3; a compound that is constantly added to smelting pots to maintain bath chemistry. This will be achieved through controlled manipulation of iconic equilibria to achieve optimum AIF20H yield, particle size and purity. The expected outcome is a decision on whether the process should progress to pilot plant stage.