The electrolytic production of aluminium is undertaken in large smelters containing carbon-lined pots in which carbon acts as the cathode, the pots having a life typically of 2 to 6 years. Eventually the potlining is incapable of performing electrically and a toxic waste product of enormous tonnage is created. The potlining is heavily contaminated with metals, fluorides, cyanide and other compounds. The carbon content is reduced to less than 50%. Spent potlining (SPL) has been dumped in rivers, at sea and on land, creating major environmental problems. Today most spent potlining is stored at great expense awaiting a safe treatment process. The paper describes a low temperature chemical extraction process which has been demonstrated to recover valuable by-products from the SPL, leaving an environmentally acceptable landfill solid product. A demonstration plant has been built and plant trials have been performed. Cyanide is adequately removed in the water wash stage and fluoride is recovered as CaF2. The acid washes remove the rest of the fluoride and a significant quantity of this is recovered as AlF3.