The lcl&l process: A sustainable solution for the treatment and recycling of spent potlining

Abstract

Spent potlining (SPL) is a hazardous waste produced by aluminum smelters. SPL is generated from the internal lining of A1 cells, constituted of carbon and refractory bricks and replaced after five to eight years in service. It is classified as a hazardous waste because of its contamination with fluorides and cyanides and its reactivity with water, generating explosive gases. Nowadays, the aluminum industry has made some progress with the SPL issue by recognizing that landfilling is no longer acceptable by most local communities. In 2008, Rio Tinto inaugurated a new plant in Jonquiere (Quebec) for the treatment of 80 kt of SPL annually, based on the low-caustic leaching and liming process (LCL&L, patent no. US 6,596,252) developed in the early 1990s. This paper describes the advantages of the LCL&L technology, including valorization routes for its by-products and the successful ramp-up of the plant to its nominal capacity reached in 2014.