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Sensor-based sorting solutions provider for the mining industry, CommodasUltrasort, is the mining division of internationally renowned Norwegian-listed Tomra Systems ASA, and will exhibit at Electra Mining under its new name Tomra Sorting Solutions.

Tomra Sorting Solutions South Africa’s general manager, Lütke von Ketelhodt, says he is pleased with the name change as it unequivocally identifies his operation as part of the one of the world’s biggest and most technologically advanced sensor-based sorting companies.

“We are part of a financially powerful group, which not only emphasises the importance of ongoing R&D, but has the muscle to make this a reality. As a result, we are constantly ahead of the game with respect to new sensors and improved technical designs of the equipment and the mines we are supplying to are proving this to be the case,” von Ketelhodt says.

Chrome

SS’s X-ray Transmission (XRT) sorting technology is producing is better than expected results in the separation of lumpy chrome ore from waste rock at a chrome operation situated on the western limb of the Bushveld Complex.

Its XRT chute sorter has been operating on a full production plant at the mine processing 70 tph at >90% availability. After blasting and trucking, the ROM is crushed and screened, and the -60 mm to +20 mm material is delivered to the XRT sorter, while the rest of the material is transferred to a conventional beneficiation plant.

The feed grade into the XRT sorter averages approximately 32% chrome and the process upgrades the saleable product to 36% or better, at 97% efficiency.

Diamonds

Another TSS success has been on one of the largest diamond mines in the world based in the Southern African region. Between March and August 2011, a pilot study was conducted on a prototype XRT belt sorter, feeding material with various throughputs and size ranges, and producing a total recovery greater than 98%.

The mine was seeking a new method of recovery for large diamonds, prior to tertiary crushing.

The main advantage of the XRT technology in this application is that it sorts on an atomic density rather than according to physical characteristics or properties such as relative density and luminescence. As the luminescence properties are not always consistent in diamonds, a technology was required that would recognise all diamonds, regardless of their physical properties.

“Our XRT is able to see the atomic make-up of each particle going through the detection zone of the machine. A diamond, which consists of covalently bonded atoms forming so-called ‘diamond molecules’, appears in a distinct light-grey X-ray image,” explains Von Ketelhodt.

Coal

On one of South Africa’s leading coal mines, the company’s PRO Secondary XRT sorter reduces the ash content of coarse raw coal from an average 37.3 to 17.8%. The sorter also improved the coal calorific value from 17.9 to 25.0 Mj/kg and simultaneously reduced the sulphur content.

“In the process we also proved that our PRO Secondary XRT sorter is capable of processing up to 150 tph of coarse raw coal, effectively removing the bulk of the contaminant stone in the raw coal with all the associated benefits.”

Robust and environment-friendly

No slurry is produced with XRT technology, resulting in reduced groundwater pollution due to acid drainage and salt accumulation in water circuits. It is also less capital intensive because it does not require the extensive infrastructure and water handling requirements associated with dense medium separation.

The TSS sorting technologies are also relevant to today’s mining conditions. “Increasingly we face challenges such as low-grade ore reserves, high energy costs, water shortages and stringent environmental legislation. Sensor-based sorting is a very significant innovation in mineral processing technology and upfront beneficiation.”

Sidebar:

Tomra Sorting Solutions provides sensor-based sorting solutions to the mining industries. Over the past 20 years, it has installed more than 10 000 sensor-based systems in more than 80 markets worldwide. This includes more than 180 sensor-based sorting machines in mining and mineral processing applications across the globe, successfully sorting a variety of minerals and ores including coal, industrial minerals, platinum, gold, diamonds and tanzanite.

TSS products are incorporated into three main product lines: the ROM series of belt sorters, suited to coarse primary ROM material up to -300 mm; the Industrial Processing (PRO) Series, comprising chute-fed free fall sorters for primary, secondary and tertiary ROM material; and the Gemstone (GEM) Series, comprising sophisticated wet-dry sorters for diamonds, emeralds, tanzanite and other gemstones.

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