Tuesday, 11 October 2011

US firm to 'mine' lithium from geothermal plant brines

3 Oct 2011

A US company is looking to geothermal power plants as a source of valuable metals such as lithium which is crucial for manufacturing electric vehicles and portable electronics like smart phones. Its success could better position the US in the fast growing electric vehicle (EV) and broader battery markets. The US supplied roughly 75% of the world's lithium through the late 1990s, but now that figure is now closer to 5%. Worldwide lithium production is currently dominated by Chile, Argentina and Bolivia. But that could all change.

California based Simbol Materials says that it has begun producing 'the world's highest purity' lithium carbonate for use in electrolytes for EV batteries and other energy storage applications. The company has opened a demonstration facility near the Salton Sea in Imperial Valley, California, that can extract lithium and other components of lithium-ion batteries from the wastewater of geothermal plants. This is the first facility of its kind in the US, though other companies operate two similar ones in Japan and China.

'For the US, this is a nice move forward in lengthening the supply chain for the components that go into electric vehicles,' Simbol's CEO, Luka Erceg, tells Chemistry World. Simbol taps a nearby geothermal power plant for its brine by-product, which is laden with metals. After removing silica, Simbol's end product is a pristine brine that is loaded with lithium, manganese and zinc. 'Once we have separated out the metal we want, we have got it in a chloride form and we start the conversion to the products that the market wants,' Erceg says. But such separation is no simple task. The brine that Simbol works with contains half the periodic table. 'We can surgically extract the elements that we want, and that is where we differentiate ourselves from the majority,' Erceg says.

Proprietary processes
Simbol's proprietary processes involve membrane separation, absorption media and direct precipitation techniques. 'These are all very conventional tools in a chemical engineer's toolkit, but what we have done is develop processes and specific materials that help us more efficiently do these separations,' Erceg explains. Not only is brine based production of lithium economical because it integrates directly into existing geothermal power plants, it also eliminates traditional methods of invasive mining or evaporation ponds that require significant land, water and energy use. Additionally, it produces virtually zero waste.

The process could be applied to other geothermal plants, although some have far lower concentrations of lithium. But, theoretically, Erceg says it could replace all other forms of lithium mining because it is significantly cheaper than building or expanding new solar evaporation processes and plants. The geothermal plant supplies power to free the brine, excess steam, condensate and CO₂ that Simbol uses in its processes. The US Geological Survey (USGS) estimates that the US produces less than 15% of the world's lithium, but it is the largest importer of lithium carbonate. Worldwide consumption of lithium carbonate is about 125,000 tonnes annually, and the US consumes roughly 8000 tonnes a year.

David Summers, who directs the Missouri University of Science and Technology's rock mechanics and explosives research center, says Simbol's work represents a 'logical' development. 'Increasingly, lithium is being used for batteries and the market for that is growing,' he says. 'If we can produce this stuff domestically, we achieve a certain measure of independence...not held to a degree hostage by those who supply the product.' The company's current demonstration plant will be followed by commercial-scale plants that will produce lithium, manganese and zinc. It expects to break ground in late 2012.