According to Australian mining, recently Sandfire Resources, a gold and copper producer based in Western Australia, announced its new solar power plant will soon start powering its DeGrussa mine. By replacing diesel power, the 10-megawatt power station, with 34,000 panels and lithium storage batteries, is expected to reduce the mine’s carbon emissions by 15% .
“This is an exciting development because it realises an important potential that has long been recognised but not exploited. Two of Australia’s greatest resources – solar energy and minerals – are, as luck would have it, both highly concentrated in the same parts of Australia.”
In metal production, most greenhouse gases are generated when carbon (often coal) is used to produce metal from the rocky ore. Some of this carbon is used in the actual chemical reactions, but a large proportion is just providing energy for the process.
The next revolution
Mines are often isolated. There is typically limited natural gas and electricity supply, and in remote areas energy supply is limited to liquid fossil fuels. This is exactly the potential being exploited by Sandfire Resources at its mine facility 900km north of Perth.
Recent studies by CSIRO have identified the potential to use solar in high-temperature processing of ores such as bauxite, copper and iron ore. This process would use concentrated solar thermal (CST) energy as a heat supply. This heat can also be converted to electricity, known as concentrated solar power (CSP).
Solar thermal energy works best at temperatures between 800℃ and 1,600℃ – which can be achieved with existing technology that concentrates the sun’s heat. This is currently too hot for converting the heat to electricity, which generally operates below 600℃.
But processing minerals can make use of these high temperatures, because the heat is used directly for chemical conversion, rather than first being converted to electricity.