ORE SORTING
reduce processing costs by rejecting around 70 % of the ore fed to the sorters , according to Tungsten West . This comes on top of recent sorting unit sales in chrome and manganese operations in South Africa , and iron ore in Brazil .
Up for the challenge
IMA Engineering has recently recorded some big ore sorting wins in Brazil and the iron ore sector , respectively .
The Brazil win is at a nickel operation where the results will be used as part of a much wider ore sorting research project for a large mining company , and the iron ore contracts will see two of the company ’ s on-line Fast Conveyor Analyzers ( FCAs ) installed at two CMP ( Compañía Minera del Pacífico ) iron ore mines in Chile .
Ilpo Auranen , Chairman of IMA , said of the CMP installations : “ We have had a rental unit there for some time and they have now signed off on two commercial units – one for each mine . We have just received an order from a mine where they will use IMA FCA for a bulk ore sorting study for analysing material after the primary crusher and then also the secondary crushed mill feed . With this application , there are intermediate stockpiles in between . This approach gives them an understanding of how the intermediate stockpiles homogenise the material and how it behaves throughout the process and where to place the bulk ore sorting system in the process .”
To this point , IMA ’ s focus has been on using XRF-based sensors for bulk sensing and sorting applications , but Auranen said the company is now working on combining its own offering with that of a particle sorting vendor .
“ We are looking into combining particle and bulk sorting , studying if we can do primary and secondary sorting via the two methods ,” he said . “ It ’ s the same principle as having primary and secondary separation in your processing flowsheet .
“ As always with these studies , we need to find a site . Our bulk sorting studies can easily be carried out by installing a sensor above the conveyor for data acquisition , but the particle sorting trial involves taking expensive equipment to site for testing . We are discussing collaborations and testing with the particle sorting companies at the moment .”
This move has been prompted by a specific client request , and Auranen said more miners have been coming to the company looking to solve specific operational issues on site with a range of solutions on the market .
“ We still believe the optimal solution is using bulk sorting , which might be improved slightly with something else like particle sorting ,” he said .
Auranen is hopeful that the increasing use of in-pit crushing and conveying ( IPCC ) technologies in mining applications – on the back of the need to reduce emissions and energy use – will provide more bulk sorting opportunities for companies like IMA .
“ An ideal application for bulk sorting is IPCC – you do the primary crushing , put the material on the conveyor and , in a typical open pit , you would need two conveyor lines , one for ore and waste ,” he said . “ With bulk ore sorting , you only need one line , and you can put ore and waste on the same belt and sort it outside of the pit limits . There are several potential existing sites that could utilise this solution right away .”
The company ’ s efforts to enter the IPCC space are being aided by the fact its FCA solutions can now carry out sensing in five-second intervals , compared with the previous generation ’ s 30- second capacity .
“ This means the minimum sortable mass is much smaller ,” he said . “ The shorter the analysis time and the smaller the batch size , the more grade variation you see . With the new detectors , there are fewer trade-offs than there were in the past with speed and accuracy . The accuracy evens out with time much faster in these fivesecond intervals .”
A further area of interest to many mines and to IMA is how to increase mill throughput .
“ The grinding mill is often the bottleneck for concentrator production , with mill production often varying significantly depending on the ore type ,” Auranen said . “ Mill capacity is dependent on ore grindability ( ie hardness ) and often waste rock is harder to grind than the ore . Another critical issue in mill efficiency is the mill feed size distribution .”
IMA believes it can address this area by combining ore grindability and mill feed size online measurements via sensor fusion to its bulk ore sorting solutions .
Ore stream sorting and digitalisation
Rados International also sees a strong business case for applying bulk sensing in IPCC applications , with the company having designed a specific offering for this market .
It is also abundantly aware of the need to incorporate both bulk ore sorting and particle sorting with a suite of XRF-based solutions that cover off both technologies .
The company says its proprietary Rados XRF + analysers conduct primary analysis of metal or proxy markers , rather than secondary analysis of
IMA Engineering is installing two on-line Fast Conveyor Analyzers at two CMP ( Compañía Minera del Pacífico ) iron ore mines in Chile
other characteristics . This sensing is complemented by a proprietary mechanical actuation system to facilitate a particle-byparticle sort for low volume applications of 500 t / h or below .
The company argues , in this case , that integrating its own mechanical sorting solution with its own XRF-based sensors ensures improved accuracy of the sorting process .
When it comes to bulk sorting for higher volume operations of more than 500 t / h , Rados highlights the “ unique ability ” of the proprietary Rados XRF + analyser to accurately measure ore grade in less than 10-second intervals ( notwithstanding large variations in run of mine ( ROM ) ore particle size distribution ) and leverage a proprietary actuation system that can actuate in less than 10-second intervals as market differentiators .
Rados is also advocating for increased use of ore sensing and sorting IPCC applications for volumes up to 10,000 t / h .
“ The Rados XRF + waterfall analyser , in combination with in-pit materials handling equipment ( continuous miners and in-pit crushing and conveying stations ), provides in-pit sorting solutions premised on the direct analysis of the grade of the ROM ore ( including preprimary crushed ore ), providing rapid and accurate data ,” it said .
This data can be used to facilitate separation into higher- and lower-grade streams using the specific materials handling process .
XRF may be the main sensing solution that Rados leverages to carry out the aforementioned processes , but the company says its “ XRF +” offering is both a “ highly differentiated ” and “ enhanced ” version of XRF technology that integrates proprietary software and algorithms , artificial intelligence ( AI ) and proprietary hardware .
46 International Mining | MARCH 2022