New smelter could save energy

Materials World magazine
,
1 Jun 2008

Following the acquisition of Alcan last year, Rio Tinto has announced the evolution of Alcan’s aluminium production (AP) technology through a smelting process that consumes up to 20% less energy. The system will be scaled up next year at the company’s pilot plant in St Jean de Maurienne, France.

The AP-Xe project is based on heat recovery, low resistance cathode blocks and drained cathodes, which are ‘cells which operate with little or no liquid aluminium in the bottom. The metal is “drained” from the cathode,’ explains Stefano Bertolli, Spokesman for Rio Tinto.

‘They allow cells to operate at a smaller distance between the anode and the cathode, reducing the energy [needed to run it].’

Both Rio Tinto and Alcan have investigated these cells in the past. However, their structure relies on a composite of titanium diboride, which, while able to withstand high temperatures and resist molten aluminium and electrolyte, is expensive to produce.

Rio Tinto worked with the Australian Commonwealth Scientific and Industrial Research Organisation to create a low-cost method for manufacturing high-quality titanium diboride for aluminium smelting.

The AP-Xe process also builds on Alcan’s AP50 technology, which is ‘the highest productivity cell design in the world’, says Bertolli. The AP50 smelter uses only one potline (336 pots), with a larger electrolytic pot than previous technologies, operating at 500,000 amperes of electricity. It is estimated to produce around 485,000t of aluminium a year.

‘Integrating [Rio Tinto and Alcan’s] programmes and teams of scientists will accelerate the industrialisation of this technology,’ he adds.

Tests of the high amperage cells will begin next year in France, with the separate components of AP-Xe progressively combined in trial groups over the next three to five years.

 

Further information:

Rio Tinto