The main sites of ion-adsorbed clay deposits of rare earth elements are in South Australia. These clays contain four key elements used in magnets for electric cars and wind turbines: neodymium, praseodymium, dysprosium and terbium.
Flour And Grain Packing Machine For Open Mouth Bag
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Typical NdFeb magnets in electric vehicle (EV) motors consist of 29 to 32 per cent neodymium and praseodymium, with another 4 to 9 per cent of mass being terbium and dysprosium. However, the latter two elements increase the maximum operating temperature of the magnet from about 60 degrees Celsius to 240 degrees Celsius, a key factor for electric vehicle traction motors.
This means that the economics of ionic clays are more attractive than hard-rock rare earth deposits. Unlike hard-rock deposits, these clay deposits are shallow, require negligible blasting, involve no crushing or grinding, and have no radioactive tailings of uranium or thorium to dispose of.
That's why Christopher Ecclestone, a mining analyst at London-based Hallgarten & Co, recently called ionic clay deposits the "holy grail" of the rare earth industry.
The relative ease with which these clays can be mined, and the improved economics of rare-earth element production that this brings. Meanwhile, China is running out of heavy rare earths. The supply crunch was foreseen in a 2013 paper from Peking University's Department of Environmental Science and Engineering, which suggested that China's heavy rare earths would run out in 10 to 15 years.
Clay deposits were discovered in Ganzhou, Jiangxi Province, in 1970 and subsequently in other southern provinces such as Guangdong, Fujian, Zhejiang, Hunan, Guangxi and Yunnan. The main ore bodies are located between 5 and 30 meters above the surface, so rare earths can be extracted by open pit mining followed by heap leaching.
Although these clays account for only 2.9 percent of China's total rare earth reserves, they are vital to the country; Between 1988 and 2007, these clays accounted for 26 percent of total rare earth production, rising to 35 percent in 2009. However, production has dropped recently as the country has implemented stricter environmental controls and cracked down on illegal mining.
The breakthrough in South Australia comes against a backdrop of China tightening its grip on rare earths, now tightly controlled by the merger of three Chinese producers - China Minmetals Rare Earth Corporation, China Aluminum Rare Earth Metals Corporation and China Southern Rare Earth Group.
Earlier this month, Taruga Minerals reported that samples from its Morgan's Creek project in the Adelaide Fold belt had confirmed the presence of high-value rare earths in clays. The average recovery rate for total rare earth oxides (TREO) is 85 percent, and 93 percent for high-value magnets, the company said.
South Australia's ionic clays are more attractive than hard-rock rare earth deposits. Also this month, Resource Base announced what it called "excellent" results from shallow hollow drilling at its Mitre Hill project in the Murray Basin straddling the border between Victoria and South Australia.
The drill found mineralides 3 m above the surface, with 1 m TREO at 1421ppm and another borehole intersecting 1 m at 1090ppm (5 m above the surface).
In mid-May, iTech Minerals also had success with its Ethiopian kaolin mine on Eyre Peninsula. Reporting results from the first 23 of 115 boreholes, the company said they confirmed significant levels of rare earth elements in the clay, including 1057ppm at 12 meters at 7 meters. These discoveries have made South Australia a hot spot.
