Resource World Magazine

50 www.resourceworld.com o c t o b e r / n o v e m b e r 2 0 1 5 MININGWORLD ToMRA ore sorting machine increases grades and profits Founded in 1972 by brothers Tore and Petter Planke, TOMRA Systems ASA [TMRAY-OTC; TOM-OSE] is a Norwegian multi- national corporation. Interestingly, the company's technologies cover a variety of industrial sectors, including food, recycling and for this article – mining. The company's business area, TOMRA Sorting Solutions, man- ufactures ore sorting machines that utilize several different types of sensors, including X-rays, to differentiate different grades of ore; waste rock is discarded or low-grade ore is separated from high-grade ore. It is well-known that some diamond mines use X-rays to separate diamonds from the waste host rock, kimberlite. The TOMRA ore sorting machine uses related technology on base metal ores, precious metal ores and industrial minerals. In an interview, Harold Cline, Area Sales Manager Mining, for TOMRA in Denver, Colorado, spoke to Resource World. "TOMRA's ore sorting technology is becoming much more popular for base metals mines," said Cline. "We can use a tech- nique similar to what they use for diamond sorting called X-ray transmission. With diamonds, you are looking for pieces of car- bon which have a very consistent atomic density, whereas with base metals, we are looking directly for base metal sulphides of lead and zinc that show up very well with X-ray transmission. It's also a possibility that they could show up with color which can separate gangue minerals from ore or some sort of alteration." Cline explained that we can look inside the rock and see sulphides, just like we can X-ray a human and see their bones, "However, because we can see inside the rocks, they don't need to be washed. If we can separate, say non-valuable feldspars or other waste rock that is difficult to crush and grind, we can save the mining company a lot of money." After the rocks are X-rayed, anywhere from 100 to 200 air injectors are used to separate the ore from the waste as it moves quickly along a conveyor belt at about three metres per second. Air blasts then send the ore and waste to the appropriate bin. "The best crushed rock size to X-ray depends on what size the mine is getting good liberation of the valuable metal or mineral," said Cline. "So, if they are getting a good liberation at fairly coarse particle sizes, say 75 to 150 mm, then we would use the X-rays on that size of rocks. Although sorting would be slower, we could go down to 10 to 15 mm in size, if needed, to get a better separation for the customer." Cline noted that TOMRA has been standardizing the technol- ogy to a large degree, making it more cost-effective; however, TOMRA tests the client's ore samples at its testing facilities to customize how the machine responds and how the sorting is executed to suit the ore deposit's particular characteristics. "We can increase the head grade of the ore going to the mill," said Cline. "The cost of the TOMRA sorting machine varies according the specific application requirements." Over 200 TOMRA ore sorting machines are in use around the world for various minerals includ- ing diamonds, base metals, gemstones, limestone, coal, gold and industrial minerals. Minera Alamos plans on using a TOMRA ore sorting machine at its Los Verdes copper- molybdenum project in Sonora, Mexico – see article page 44. n An example of a typical TOMRA ore sorting machine. Illustrations courtesy TOMRA Sorting Solutions. Cross-section of TOMRA ore sorting machine.

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