The importance of ore sorting

Ore sorting is an important facet of the mining industry and it’s on the up. Australian Mining looks at two Australian companies that are collaborating on the cutting edge of the industry.

Ore sorting is an increasingly prominent way for mine sites to maximise uptake. In recent years, a wide array of sensor technologies has come to the fore, each tailored to a different mineral or sorting application.

X-Ray Transmission technology (XRT), LASER, near-infrared (NIR), colour scanning and electromagnetic sensors (EM); these and other technologies are at the forefront of mineral separation technology.

Typically, high-performance ore sorters of the type found at modern sites, work by scanning passing material via a belt or chute feeding system and identifying mineral properties with the scanner of choice.

Material that passes one or more selection criteria is identified by the scanner and separated into two chambers via a precise burst of air.

XRT scanning, possibly the most common type of ore scanning technology in mining applications at the moment, scans the internal mineralogy of the rock in minute detail, with X-ray penetration with the unique ability to show the makeup of particles within the rock.

LASER scanning is another popular method, particularly for the identification and subsequent grading of quartz or gold-bearing quartz via the diffusion, dispersion and diffraction of the LASER light through the material.

TOMRA Sorting Solutions, an ore sorting-focused subdivision of the company TOMRA, is constantly pushing such technologies further. In the last few years its XRT technology has evolved from being able to scan rocks down to a detail of just 0.8mm, when just a few years ago 4mm was considered an impressive feat for the technology.

Anthony Sacca, Managing Director of TOMRA Sorting Solutions Australia, compares the speed of the sensor and ore sorting technology’s evolution to the likes of smartphones, digital cameras and computer hardware, which all tend to see large leaps in capability in a relatively short time frame.

“In terms of development we’re starting to push our LASER and XRT tech, getting higher and higher resolutions of material as it goes through the machine at higher and higher speeds,” Sacca tells Australian Mining.

“It gives us an amazing ability to be very selective and discriminating, which gives our customers great capacity and throughput on the machine with a very high degree of recovery and selectivity of what gets pulled out.”

TOMRA is one of the leading ore sorting providers in the country, offering full-scale indoor test centres for prospective customers to get a hands-on for the company’s machines and learn more about the process.

“We can actually run full scale demonstration — real, full size mining machines in our test centre,” he says. “We don’t scale them down. We could pull them out of the test centre, put them in the field and they would run.”

When implemented well, ore sorting machines can greatly improve plant efficiency, reducing downstream crushing requirements and costs, and resulting in much improved grades. It can even benefit the operator’s carbon footprint since waste is rejected at an early stage, which in turn reduces the need for tailings treatment.

TOMRA Sorting even includes a ‘green counter’ on its website that measures the levels of carbon dioxide saved through the adoption of its machines at mine sites in metric tonnes. From January 1, 2018 to the time of writing, it stands at just over 56 million tonnes (Mt), roughly 9.3Mt a month.

“We have the ability to remove and clean up legacy issues associated with high sulphide and acid forming and partially acid forming waste ores,” says Sacca. “We can help clean up all those areas as well. One of the nice things we’re also looking at today is because of all those that we are giving mining operations a much smaller carbon footprint.”

Over the past three years, the company has developed a solid working relationship with Ore Sorting Australia (OSA), a company that grew from Crushing Services Solutions (CSS) in 2015 as a uniquely placed mobile platform for site-to-site ore sorting.

OSA carried out its first large project in December 2016 and has continued to grow since, firmly establishing itself as a turnkey, cost-per-tonne provider of ore sorting solutions, particularly for low-grade stockpiles that might otherwise be ignored.

If the ore sorting is applied to deposits, there may be an opportunity to lower cut off grades therefore increasing the overall return and/or make lower grade deposits profitable,” explains Darren Tarrant, Operations Manager at OSA.

“OSA has developed a business model in which we can provide a ‘one-stop shop’ for companies, either for treatment of low-grade stockpiles that may not be otherwise cost effective to process, or development and installation of ore sorting into existing plants to improve performance on a short-term contract basis.”

Together, TOMRA Sorting and Ore Sorting Australia, while separate companies, have worked together to keep abreast of the times, communicating on upcoming projects and assisting clients in ways that are of mutual benefit to each others’ operating strategy.

“We have had a very strong working relationship with the CSS and OSA guys over the last couple of years,” explains Sacca. “We built that on an open and honest relationship where we looked at applications jointly and where they fit in nicely to our business models.

“We are quite complementary to each other; OSA’s model is unique in its ability to mine the material, haul it, crush it, screen it, wash it, sort it and then dispose of, stockpile or treat material.”

Both companies have noted an upward trend regarding consumer interest in ore sorting technology in the last year to 18 months. It seems the word is getting out.

Ore Sorting technology has come a long way in the past five to seven years and is becoming more accepted within the industry — “It’s an exciting time,” concludes Tarrant.

 

This article appears in the August 2018 issue of Australian Mining.