Get it sorted

Paul Boughton

Kai Bartram looks at the use of sensor sorting technology in the mining industry and how it can to 'unlock' additional value from the minerals.

Sensor sorting technology developed in Germany by STEINERT Elektromagnetbau GmbH has been applied in the scrap metal and waste recycling industries for more than a decade.

Now, says, Johan van Zyl, Product Manager of STEINERT Australia, this technology has been adapted and redesigned to suit the mining and minerals industry.

Van Zyl explains: “Ore sorting is a process for upgrading mineral bearing rock at large particle sizes, typically between 250mm and 10mm and involves evaluating the mineral content of individual rocks as they pass through a sensor, then separating them into Accept and Reject fractions, based on pre-determined selection criteria. Ore sorting requires a property specific to an ore to be sensed and then optimised for each application.”

Depending on the particle size range of the material being treated ore sorting machines can operate at throughput rates up to 200 tonnes per hour per machine. It is possible to adjust machine sensitivity and the cut-off grade for the accept/reject split. This fine tuning gives flexibility to operating requirements, for example, high upgrade ratios or maximum recoveries. Then the crushed rock or gravel is screened into size ranges.

A recent example is the installation of a 2m wide x-ray transmission (XRT) sensor sorting system at the Wolfram Camp Mine (WCM) in Northern Queensland for the removal of waste rock after the primary crusher in order to reduce the load on downstream processes. 

Why use sensor sorting?

Van Zyl says: “A sensor sorter does not require water in its operations, therefore eliminating the possibility of acid water. It is also energy efficient as it accurately detects the location of the mineral in the ore and ejects the waste, reducing the amount of material that must be crushed and transported – hence using less energy. By doing this, only the ore containing mineral needs to be transported from site. This contributes to major savings on transport costs.”

This technology has the potential to produce better quality and more consistent coal/mineral product in the industry, adding that the desired product does not need to be seen in the ore by the naked eye as the machine will detect it.

With this in mind - projects can be brought onto the market quicker and junior coal miners and small coal operators have the opportunity for a quick start-up – bringing coal standards up to required specifications.

The STEINERT XSS T can be modified and the software used will be unique to each application.

Van Zyl says this technology is not to be a replacement for conventional technologies. He hopes that the STEINERT XSS T can be seen to work in conjunction with traditional technologies – thereby providing an additional step in the mining process – but also assisting in the reduction of operating costs.

Kai Bartram is Business Development Manager, STEINERT Elektromagnetbau GmbH,  Cologne, Germany.

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