Primary aluminium production is an energy intensive electro-chemical process. On average, it takes 13.7 kWh to produce one kg of metal, and over decades this value has little improved due to the significant scientific and technical challenges to be addressed. Over the last years, energy scarcity and price trends have nonetheless triggered a market demand for lower consumption technologies.
Rio Tinto used high performance R&D development tools and its unique European Technology piloting facility in France in taking up this challenge. Between 2010 and 2014, an intensive program based on modelling and tests has been launched. In cooperation with an international University Network (Ecole Polytechnique Fédérale de Lausanne, Coventry University, Polytechnique Montréal, Université de Quebec à Chicoutimi) Rio Tinto has developed a unique suite of inter-connected models able to simulate the full behaviour of the Electrolysis Cell and to deliver optimised designs. These specific designs have been successfully tested at the Saint Jean de Maurienne (France) pilot facility.
The APXe prototype cells in St Jean de Maurienne are now operating in a range of 500 to 520 kA with energy consumption as low as 12.0 kWh/kg, achieving in 2016 - for the first time in the industry - a simultaneous benchmark for energy consumption and productivity. The object of the next stage of development of these high amperage and low energy cells is to achieve 11.8 kWh/kg or less by 2020. APXe has already been selected as the technology of choice for a potential greenfield smelter in Asia.