PRECONCENTRATION AND ORE SORTING
Because sorters operate on defined size fractions, mines can also retain coarse material that would otherwise be crushed away. This allows waste to be managed in a form that is immediately suitable for placement, while preserving processing capacity for mineralised material.
At Bluestone’ s Renison Bell operation in Tasmania, Australia, the value of sorting lies in confidence and control. XRT sorting is used to separate non-acid-forming from potentially-acid-forming( PAF) waste, allowing the operation to manage material according to its long-term environmental behaviour.
“ By separating non-acid-forming waste using TOMRA XRT sorting, we are able to place a large portion of our waste rock directly in long-term storage, reducing both environmental risk and the need to place underground,” the Bluestone Mining Tasmania Joint Venture says.
This segregation simplifies waste management and closure planning by ensuring that only chemically stable material is placed in long-term storage, while PAF material is isolated and managed appropriately.
At Kensington Mine in Alaska, USA( owned by Coeur Mining), XRT sorting reinforces the same principle: clean waste is usable waste. High-density particles containing sulphide minerals and associated gold are recovered into the concentrate stream, while low-density diorite pebbles, virtually devoid of sulphides, are rejected as waste. This process not only enhances gold recovery but also produces a barren waste fraction with minimal acid-generating potential, supporting environmentally responsible tailings management.
“ In the latest publicly available technical report, 4,216 oz of gold were recovered from the pebble sorting operation in one year,” Jordan Rutledge, Area Sales Manager at TOMRA Mining, says.
The Mt Carbine operation in Queensland, Australia, is a strong proof point for waste-toaggregate sorting, TOMRA says. At the EQ Resources operation, TOMRA XRT sorters are used to process tungsten-bearing ore, generating a barren waste stream that is repurposed as aggregate for sale.
“ Normally you would grind the waste down to 6 mm and put it through the jigs, but, by putting it through the TOMRA sorters, we are able to keep a whole range of aggregates on the coarser size fractions,” Kevin MacNeill, CEO of Mt Carbine mine, EQ Resources, says.“ The sorters remove any material containing acid-forming sulphides and the waste rock that comes out is incredibly clean. We are therefore able to use it in making all kinds of different quarry products – from road bases to concrete aggregates.”
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Pointing to value generation
At the Navachab Gold Mine in Namibia, sorting technologies from STEINERT are increasing gold recovery and reducing operating expenditure, according to the company.
Navachab is a low-grade gold ore operation that upgrades its resources using STEINERT’ s suite of dry sorting processes. It has been using STEINERT XSS T sorters since 2016. Over the last decade, these sorters have preconcentrated over 10 Mt of low-grade stockpiles and turned it into valuable ore. Navachab Gold Mine has now installed the next generation of STEINERT’ s sorting systems.
The next evolution being considered is a doubling of current treatment capability. Compared with previous processes using Dense Media Separation, SBS now runs at a quarter of the overall operational costs, while doubling throughput. For these reasons, and because this process does not require water, it plays a key role in the future.
Hildebrand Wilhelm, Navachab Ore Processing Manager, referenced the a higher chance for composite objects to be identified as only one particle. This can result in incorrect sorting decisions such as valuable ore being classified as waste, or waste being classified as a valuable material.
During the gold ore detection process, declustering ensures individual particles are detected separately for proper classification. This feature improves the accuracy and efficiency of the sorting system, while allowing higher throughputs to be processed.“ With STEINERT’ s Intelligent. Declustering, the software extracts the individual rock from the cluster, even if the particles are very close together, and analyses it,” the company says.“ The benefit of this process is that it now makes goals which were previously mutually exclusive compatible. Besides this, it is possible to upgrade existing units, quickly and easily.”
The Navachab Gold Mine has opted for a multi-sensor sorting solution and is now benefitting from updating the STEINERT KSS to the EVO 6.0 version, which significantly improves sorting system handling, according to the company. The operator can simply
To prevent the valve bank from becoming clogged during maintenance work on the KSS EVO 6.0 unit, the valve bar can now be swung up, STEINERT says
detection rate per second – and the fact that the dry sorting plant sorts 200 t / h to detect material falling below the carbonin-pulp plant cut-off grade.“ That is where the value is generated because then – with the doubled grade – the material can be profitably treated by the downstream processes,” he says.
The former sorting systems were robust, reliable and withstood 10 years of harsh and dusty mining conditions, but the newest STEINERT KSS EVO 6.0 sorters provide even more benefits, according to the company. Particle sorting technology typically analyses and makes decisions regarding individual defined particles on the conveyor belt. When increasing throughputs, there is walk into the machine to inspect it and the integrated rolling platform permits quick and safe access to the valve bar and conveyor belt.
During sorting, the valve bar ensures that the sorted material is ejected. To prevent the valve bank from becoming clogged during maintenance work, the valve bar can now be swung up. The pneumatic unit has also been re-arranged and is easy to access. The operator also benefits from a permanently integrated railing with ladders, allowing the 3D and colour sensors to be accessed quickly and safely without requiring climbing gear.
International Mining | MARCH 2026