PRECONCENTRATION AND ORE SORTING
GEOSCAN-M for bulk ore sorting of nickel laterite ore at Barro Alto in Brazil
In 2010, Xstrata( now under Glencore) used a GEOSCAN-M on lead-zinc ore feeding the Mount Isa Heavy Medium Plant to improve the existing preconcentration process performance. This was possible because the change in density set point could be adjusted as the quality of the feed ore varied. This improved on the previous practice of using a“ 30 % by volume” discard rate independent of feed quality, which resulted in too much ore reporting to the waste stream when feed quality was higher quality and too much waste being recovered when feed quality was lower, Scantech explained.
GEOSCAN-M performance was improved from typical two-minute analysis parcels to average analysis of each 30 seconds of flow in the mid-2010s.“ This significantly improved selectivity as the parcel size could be reduced in many cases to < 10 t, which is smaller than most loader buckets,” the company explains.
GEOSCAN-M analysers were installed in copper operations in 2017 and 2018 to assess bulk ore sorting improvements on mine-to-mill flows at New Afton in Canada( 1,300 t / h) and multiple Anglo American copper sites with mobile bulk sorting plants including El Soldado( 500 t / h) as part of a multi-commodity BOS evaluation process. Sensing every 4 t of material flow resulted in reject rates of 5 % to plus-20 % of material, which would otherwise have been sent to the mill.
Further analysers were installed in Anglo American nickel and platinum operations soon after for bulk ore sorting on flows from 300-4,500 t / h. Installations followed at Cu- Au sites with Highland Valley Copper, Telfer and Cadia. At Los Bronces, Carrapateena and Antamina, the throughputs got up to 8,500 t / h, according to the company.
“ In many cases the analysers were installed to assess flow quality variability as part of a BOS evaluation process,” Scantech said.
The success in copper-gold ores for copper measurement applications led to the development at Cadia and Telfer of
“ 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 direct gold measurement capability rather than using proxies such as sulphur or copper for gold as was done previously. Direct gold measurement in ores as low as 0.2 parts per million was successful but at longer measurement times, typically 5-10 minutes, which was not considered useful for bulk ore sorting, but extremely relevant for ore reconciliation and metal accounting, according to Scantech.
Further applications of BOS were evaluated for several projects for waste processing to segregate acid-generating waste or“ hazardous” waste from clean waste suitable for construction applications. These needed to be considered where storage could cause potential drainage problems, or where stacking the waste could cause instability in a dam or pile.
The key aspect of the technologies Scantech has applied to BOS, or preconcentration, is that the data is used for that purpose in addition to other purposes concurrently.“ In other words, the technologies are not point solutions for a specific application, but digitalisation tools where one application of the data collected is for parcel identification and diversion decision making.”
Other uses of the same data may have significant value to the operation which may be combined with the bulk ore sorting benefits to create a much faster payback period, the company says, adding that the high quality of the representative measurement data minimises the misallocation of material typically resulting from poorer measurement quality methods.“ It also provides additional confidence in using the data in the mine-to-mill process for effective ore reconciliation, possible downstream blending of different stockpiles, feed forward control to processing and metal accounting for the process operations,” it added.
Clean waste is usable waste
Amid mounting pressure on global supply chains, TOMRA Mining’ s XRT-based sorting technology is, the company says, helping mining companies recover valuable resources once considered waste – extending mine life, boosting efficiency and driving more sustainable critical mineral production.
The company’ s solutions allow mines to remove acid-forming material from waste rock early in the process, creating a detailed image of each rock, detecting fine-grained inclusions such as base metal sulphides, it explains. High-value, acid-forming particles are ejected from the feed stream, leaving barren, low-sulphide material that can be managed with confidence, whether it is placed in long-term storage, used on site, or sold as aggregate.
International Mining | MARCH 2026 69