PRE-CONCENTRATION AND ORE SORTING
The
concentration case
As industry conservatism creeps in, those in the pre- concentration and ore sorting game are sensing both a challenge and an oppor tunity, Dan Gleeson reports
The gulf between an ore characterisation project and an ore sorting project in an underground mining context is vast. There are plenty of options on the market when it comes to sensors able to measure grade directly or by proxy, all of which come with different sensing durations, accuracies and caveats. There are also companies able to offer the entire package – a sensor and a diverter – to enable a sort to take place on the likes of a conveyor belt.
Yet, the issue holding many mining operations back from such a diversion is the existing processes at hand.
The thought of shutting down a conveyor belt – one of the main arteries of any mine – for even a few hours to fit a diverter on is too much to bear for some. The idea that the conveyor may have to be stopped on several occasions soon after a restart for calibration purposes is another major headache for operations staff. This is even before one looks at what happens to the diverted‘ waste’ after the‘ sort’ is carried out.
Many companies in the ore sensing and sorting space have overcome these hurdles –
physical and mental – by highlighting the waste rock dilution inherent from the typical mining process in an intuitive interface or showcasing how much ore is being left on the table in transition zones that are not being fed through to the concentrator.
IMA Engineering is one such company, having developed an X-ray Fluorescence( XRF) platform for ore sensing / characterisation and sorting called the FCA, or Fast Conveyor Analyzer.
The Finland-based company has made significant headway in the industry by leveraging XRF-based sensor equipment placed over the top of existing conveyor belts to show the variability of the ore being fed through to the concentrator. It now has sensors installed across the globe in various commodities, some of which are being used in an ore sorting setup.
Much of the company’ s ore sensing and sorting success has been on surface where the tonnages are higher and the ability to change either up- or down-stream processes to benefit from the analysis typically comes with less challenges.
IMA has been looking for further options in the
10 sorters – four TOMRA XRT COM TER for fines, three TOMRA XRT COM2.0 for mid-sized particles, and three TOMRA PRO Primary Color for coarse-
sorting circuit underground mining space, too.
sized par ticles – are in the Pil lgangooraore
Its latest advance below surface has been in a mine hoist skip-based sorting application in Europe where it has been collaborating with a mining operation to install XRF-based FCA sensors on existing infrastructure. Ville Hakala, Vice President at IMA, told IM:“ This is a compelling idea as the sorting mechanism is already in place in the mine hoist infrastructure. You can effectively discharge that skip-load of material on surface in one direction
as ore or another direction as waste.”
The operation in question sees the primary crusher underground crush material before it is fed onto a conveyor belt feeding 16-t capacity skips. The FCA sensor is fitted to these skips taking, on average, four 20-second readings
between the skip being loadedd and the hoist lifting the skip to surface. An average of these four readings is calculated and fed through to the hoist control system for the hoists to enact the‘ sort’. There could be 30 skipss going to surface every hour, meaning some 400-500 tonnes of material can be analysed over that duration.
Hakala said IMA, the client and the supplier of
66 International Mining | APRIL 2025