Aluminum production paths in the new millennium

In the last two decades, the aluminum industry has seen the demise of the ASP chloride process as an alternative production path and a reduction of papers on carbothermal production options. At the same time, there has been a steady stream of articles proposing the use of drained-cathode technology (by a wettable titanium-diboride coating) and others extolling the virtues and potential materials for inert-anode technology. There was also a rush of smelter technology papers in the early 1980s claiming an achievable energy consumption of less than 12.5 kWh/kg. However, the recent emphasis has been a shift to high amperage technologies that are less energy efficient but more cost efficient. Current efficiencies in excess of 96 percent can be routinely obtained by new technologies, and even aged technologies can be retrofitted to perform at 95 percent. The challenge is to lower cell voltages, but one of the key limitations is the need to maintain adequate superheat to avoid sludge formation and electrolyte-concentration gradients. Electrochemical technologies face the same problems and challenges as present technology; the requirements are even more acute and demanding. These challenges can probably be met, however, and the industry is undoubtedly faced with interesting times as it continues to strive to be competitive.