Tag Archives: ore sorting

BHP, Norton Gold Fields and Saracen join forces for screening and particle sorting study

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A collaborative study with Australia mining companies BHP, Norton Gold Fields and Saracen on the integration of screening and particle sorting techniques is set to deliver benefits across the resources sector, according to CRC ORE.

The Integrated Screening and Particle Sorting Collaborative (ISPS) study aims to develop a robust and scientifically rigorous framework for collecting, testing and reporting results for integrated screening and particle sorting techniques in a variety of ore domains.

The study, which began in August 2019, is currently underway at BHP’s Cliffs nickel mine, Norton Gold Fields’ Paddington gold site and Saracen’s Carosue Dam gold operation, all in Western Australia. It is expected the study will further expand during its 15-month tenure to include an additional two sites, according to CRC Ore.

CRC ORE ISPS Study Program Manager and Discipline Lead – Metallurgical Engineering at Curtin University’s Western Australian School of Mines, Dr Laurence Dyer, said the opportunity existed to use particle sorting to upgrade ores.

“Trials have recently been conducted at several gold mining operations in the Goldfields region of Western Australia,” Dr Dyer said. “What commonly fails to be taken into consideration is the benefit of first assessing the natural deportment of metal to a size fraction through grade-by-size screening test work, prior to undertaking particle sorting test work.”

He added: “Missing this step has two impacts. First, there is a risk that particle sorting test results will be misinterpreted as being representative of the full sample without considering the mass balance impact of high-grade material that might have been lost in the fine fraction. This fine fraction will not be detected through the particle sorter.

“Secondly, the opportunity may exist to upgrade feed first through determining if there is a concentration of high grade to the fine (or coarse) fraction which can be separated through screening. Undertaking screening in the preparation stage of the particle sorting process will enable analysis and separation of the fine or coarse fractions of a rock mass.”

Dr Dyer said the study outcome would be a blueprint for understanding the opportunity for upgrading ore feeds, including an assessment of operational impacts, economic valuation and implementation approaches.

The three mining companies would benefit from insights and improvements generated from other sites, while CRC ORE will benefit from developing a broader understanding of the application and opportunity for applying particle sorting on a range of deposit types, he said. In CRC ORE’s case, this will be integrated with natural deportment grade-by-size screening opportunities to maximise value for mining operations, he said.

The ISPS study forms part of the CRC ORE Grade Engineering® program, which is focused on extracting metal more efficiently by separating ore from waste before the comminution process commences.

“Current industry perception is that declining feed grade is an unavoidable consequence of ore deposit geology and mass mining technologies for increasingly mature mining operations,” the CRC ORE said.

In typical crush-grind-float operations, value recovery only takes place at around the 100-micron particle size involving three to four orders of magnitude size reduction compared with run of mine feed, according to the organisation.

“For increasingly low-grade deposits, the cost of energy and capital intensity required to process and reject worthless material at micron scale drives poor productivity,” it said. “An alternative is to deploy a range of coarse rejection technologies.”

Grade Engineering is an integrated approach to coarse rejection that matches separation technologies to ore specific characteristics and compares the net value of rejecting low value components in current feed streams with existing mine plans as part of a system view, according to CRC ORE.

Dr Dyer said the Grade Engineering program and the ISPS study would be conducted through CRC ORE’s Kalgoorlie-Boulder Mining Innovation Hub and Curtin University’s Western Australian School of Mines.

“Particle sorting is an important lever of Grade Engineering,” Dr Dyer said. “Through this project, CRC ORE is looking to develop a better understanding of the value of particle sorting to upgrade mill feed, particularly when combined with grade-by-size screening.”

A not for profit organisation funded by the Australia Federal Government and the global minerals industry, CRC ORE commenced in mid-2010 and, after its initial five-year funding term, was awarded a further six years of funding until July 2021.

TOMRA sensor-based ore sorters shine at quartz operations

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TOMRA says its patented multi-channel laser sorting technology is helping unlock the “full potential” of quartz deposits.

Quartz is one of the most common minerals found in all forms of rock, but it does not exist in high purity in nature, according to TOMRA. The challenge for mining operations serving the metallurgical and engineered stone industries is to reliably deliver quartz of consistently high chemical purity.

The scattering effect of the multiple laser beams from TOMRA’s ore sorting technology can be used to separate quartz-bearing rock from waste rock, with the sensors recognising the glowing crystals that are the tell-tale sign of quartz or quartz veins.

TOMRA says large and pure crystals can be clearly discriminated from other rocks or minerals with a smaller crystal structure, regardless of the colour or chemical composition.

“TOMRA’s laser sorter also stands out for being a gravity system rather than the conventional conveyor belt, so that both sides of the material are scanned and multiple characteristics such as surface structure, size, shape, brightness and colour distribution are processed simultaneously,” the company said. “Laboratory tests and field experience have shown that the recovery of valuable rocks can be increased by 20% while improving the quality of the product.”

Jens-Michael Bergmann, Industrial Mineral Segment Manager at TOMRA Sorting Mining, said the advantages for mine operations are multiple, “from a longer life of the mine to lower operating costs and a reduction of waste, with consequent lower haulage costs”.

He added: “It also enables them to guarantee consistent high-quality of product to their customers.”

TOMRA’s laser sorting technology also has environmental benefits due to the reduced waste and low water use, as only a small quantity of water is required for wet washing the rocks at the beginning of the process to avoid dust in the processing plant.

Laser sorting also eliminates the need for hand picking, which is required with colour sorting in order to achieve the high purity levels demanded by the metallurgy and engineered stone industries, according to TOMRA. This has a positive impact on the mining operation’s health and safety initiatives, as personnel are not exposed to silicon dust in the sorting process.

Spanish company Erimsa, part of Elkem ASA, one of the world’s leading suppliers of silicon-based advanced materials, has over 30 years’ experience in quartz extraction using an environmentally friendly method, according to TOMRA.

It specialises in the production of aggregates for the construction industry and metallurgical quartz, which means a consistently high chemical purity of the quartz is paramount. It originally achieved this level of quality through manual sorting, but, in 2000, the company introduced colour sorting technology.

TOMRA said: “However, in order to achieve the high level of purity they required, the sorters were calibrated in a way that resulted in high rejection rates of material containing quartz. This meant that hand picking was still required in order to improve the recovery and ensure the stability in the quality of the quartz that is key for Erimsa.”

Carlos Forján, Quality Manager at Erimsa, turned to TOMRA for its laser technology, which he thought would enable the company to sort good quality quartz regardless of the colour: “The main problem we have is in the complexity of sorting automatically when the quartz and the rejectable minerals have the same colour. I thought that laser technology would be the way to address this.”

In 2016, following tests conducted at TOMRA’s Centre in Wedel, Germany, a PRO Secondary LASER Dual sorting machine was installed at its processing plant in Salamanca.

At this operation, the quartz is extracted and washed to avoid dust in the plant, then it is screened by size. Materials over 70 mm are hand-picked by four operators; materials under 20 mm are shipped to aggregates and quartz sand customers; materials between 20 and 70 mm are fed to the TOMRA multi-channel laser machine, which sorts out the waste material. A final quality check is conducted by two operators to remove the rare pieces with quartz content that may have been ejected in the waste by the sorter, as it is calibrated to maximise recovery.

Forján said: “The TOMRA machine has enabled us to reduce costs while increasing our yield; our production has easily increased by 20% compared to when we used colour sorters combined with hand picking. Material that, in the past, was lost to the waste pile is now generating profit for us.

High quality quartz after TOMRA’s laser ore sorting

“The stability of the quality is an important goal, and we have achieved this with the laser sorter. It has been such a game-changer in our operation; we are planning the purchase of a second laser machine to replace an existing colour sorter.”

TOMRA’s laser sorters can also be combined with other sensors depending on the requirements.

This is the case for Mikroman Mining Company, which uses a combination of TOMRA laser and TOMRA colour sorters to differentiate products according to four qualities: white and light grey quartz with low iron oxide content for engineered stones; grey and yellow quartz for the glass industry; coloured quartz for ferrosilicon used in the metallurgical sector; and coloured gravel, also for ferrosilicon, which currently goes into the waste pile.

These precise distinctions, resulting in higher product quality, were not possible before the acquisition of the TOMRA machines, and today the company operates 13 colour sorters and three laser sorters in its various plants, according to TOMRA.

TOMRA’s XRT ore sorting aids recoveries, costs at South Africa chrome mine

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One of TOMRA’s X-ray Transmission (XRT) sensor-based ore sorters is helping improve recoveries and lower costs at a South Africa chrome operation.

As South Africa chrome mining operations have increased production in the face of rising demand from stainless steel buyers, the cost of using traditional methods for separating low-grade chromite material, such as dense media separation (DMS), cyclones and spirals, has increased. XRT ore sorting, an established technology in physical separation that has proved extremely effective in mining operations for a variety of minerals, including chrome, is another pre-concentration route they are looking into.

“Its benefits are significant: less complexity in the process, considerably lower costs, higher productivity and profitability – and the added advantage of a lower environmental impact,” TOMRA, a supplier of XRT solutions, said.

The X-ray sensor accurately establishes the density of each particle in the feed, and high-speed pneumatic ejectors separate ore with high chromite content from barren or low-grade ore at throughputs between 60-200 t/h. “The resulting output is a high-grade product that is ready to sell, with no need for additional comminution,” the company said. “It is a dry process that requires no water or reagents, and is frugal in its energy consumption, resulting in a fraction of the capital expenditure and running costs of traditional methods, as well as a smaller footprint.”

Engineering and project management company P2E Consulting has first-hand experience of the advantages of TOMRA’s XRT technology in sorting chrome ore at Eastern Chrome mines, in South Africa. It was looking for a solution to improve the efficiency of the sorting plant and turned to TOMRA.

“We have installed TOMRA sorters on diamond and copper plants in the past and we believe their technology is ahead of their competitors,” Craig Meadway, Business Development Executive of P2E Consulting, said.

P2E Consulting commissioned a TOMRA COM XRT 2.0 sorter to replace an existing drum DMS plant.

“The mine used the DMS plant to produce saleable small lumpy product from the mine’s LG6 Chromite run of mine and dumps at a minimum grade of 38%, but it was very inefficient,” Meadway explains. “The TOMRA XRT sorter has resolved this issue. It is used to upgrade under value material with a head grade of 20-28%, to produce a saleable product at a minimum grade of 38% Cr2O3. It does this efficiently and at a low cost of production.”

The TOMRA COM XRT 2.0 sorter has exceeded Meadway’s expectations, with grades being achieved in excess of 40% Cr2O3 and mass recoveries of 25-30% from scalped waste resulting in chrome-in-tails as low as 12%.

“No other technology has given us such a high recovery rate. Not only that, with TOMRA’s XRT there was no water usage at all, and we didn’t need to spend on expensive reagents, so that we are producing small lumpy product for approximately 50% of the cost compared to a DMS plant,” he said.

The environmental benefits of TOMRA’s XRT solution were also an important factor in P2E Consulting’s choice of technology. “We are looking to introduce greener technologies into the mining industry. The fact that no water or chemicals are used is a major advantage,” Meadway said. “Also, South Africa has major power limitations, and the lower energy consumption when compared to DMS is a huge driving force.”

The ease of operation of TOMRA’s XRT sorters proved to be a further advantage: “It is very easy to use: once the sorter and feed system control philosophy is set up correctly, the plant runs with very little input from the operators,” Meadway said.

TOMRA’s collaborative approach and all-round support was also an important factor in P2E Consulting’s decision to turn to them for this project, according to Meadway.

“We knew from our experience in previous projects that the support from TOMRA is very good, and with the installation of this machine in a relatively new application, it was excellent,” he said. “The local team has bent over backwards to help us make this happen.”

TOMRA’s SRC ties to open new North America ore sorting markets

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TOMRA Sorting Solutions is gearing up for major sensor-based ore sorting orders from the North America mining market after signing a co-operation agreement with the Saskatchewan Research Council (SRC).

The company has won mining work across the globe over the last five or so years, moving from Africa diamond operations to a phosphate mine in Saudia Arabia – its largest installation to date (pictured) – to tin in South America and gold in Australia.

One of its more significant regional wins came in Canada, where it recently received a purchase order from Vital Metals’s Cheetah subsidiary to supply COM Tertiary X-ray Transmission (XRT) 1220/B ore sorting equipment to the Nechalacho rare earth project, in the Northwest Territories.

In announcing the order in January, Vital Metals said: “The ore sorting test work highlighted that the Nechalacho rare earth oxide (REO) project is one of the few and the first REO project to successfully use ore sorting to produce a high grade plus-35% REO concentrate without the use of reagents and water. This will substantially reduce the cost and the lead time to bring the Nechalacho REO project into production.”

Harold Cline, Area Sales Manager, Mining, TOMRA Sorting, said this win was significant as it was the first contract the company had sealed in North America following the agreement with the SRC.

SRC is now offering TOMRA clients sensor-based ore sorting process development work, testing and piloting as part of its full suite of SRC Mining and Energy services. The SRC also plans to expand these services further with the creation of the SRC Minerals Liberation Centre.

Up until recently, TOMRA had to send material from North America mining operations back to its test centre in Germany. While the TOMRA facilities in Europe are world-class, Cline said, having a location in North America could prove decisive when it comes to converting enquiries from miners to contracts.

“SRC was able to provide results to Cheetah in just four weeks,” he told IM on the side lines of the recent SME MineXchange Conference and Expo in Phoenix, Arizona.

This testing turnaround time could help TOMRA grow its mining sales in North America at a time when the region’s gold, industrial minerals, copper and lead-zinc mines are looking into sensor-based ore sorting solutions, according to Cline.

TOMRA strengthens southern Africa ore sorting ties with new regional HQ

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TOMRA says it has opened new regional headquarters in Johannesburg, South Africa, to strengthen its commitment to customers in southern Africa.

The initiative is designed to enhance customer care through even better technical support, service and training, and to ensure prompt availability of spare parts, it said. The move will also improve operational efficiencies by bringing together under one roof all three TOMRA business divisions: Mining, Recycling, and Food.

TOMRA’s new facilities are housed in a two-story, 1,800 sq.m building which accommodates offices, a warehouse, spare parts area, two training rooms, and three meeting rooms connected to TOMRA’s global network of more than 4,000 employees. There is also the space here to demonstrate TOMRA’s sensor-based sorting technologies.

The building’s location on the edge of the Longmeadow Business Estate, Edenvale, to the northeast of Johannesburg, is conveniently close to major road networks and the city’s airport.

The most senior executive at the new headquarters is Albert du Preez, Senior Vice-President and Head of TOMRA Mining. Du Preez said: “This investment affirms TOMRA’s wholehearted and long-term commitment to southern Africa. This is a growing market, and one we take very seriously. The 26-strong team operating out of our new headquarters will support customers in South Africa and all other countries in Sub-Saharan Africa.”

With the mineral industry such a valuable source of export earnings, it is hugely important to national economies in Sub-Saharan Africa, TOMRA said. The African continent can produce up to 500 t/y of gold and accounts for a large share of the world’s diamonds, according to the company.

In April last year, a 1,758 ct diamond, one of the largest in recorded history, was recovered in Botswana through TOMRA X-Ray Transmission (XRT) sorting technology. South Africa is also a crucial global supplier of chrome ore and ferrochrome, exporting 8.5 Mt of ferrochrome annually, mostly to China, and TOMRA’s sorting solutions are ideal for the production of these minerals, it said.

Speaking from TOMRA’s new South African headquarters, Helga van Lochem, Sales Manager of TOMRA Sorting Mining, said: “Opening new premises confirms TOMRA’s belief in southern Africa as a big player in the global market, and our commitment to supporting mining businesses here in the long term. Investment in sorting solutions pays back handsomely and now our new training facility in Johannesburg can empower customers to get the most from our profit-enhancing technologies.”

TOMRA says it manufactures sensor-based sorting solutions for almost every mineral application: diamonds, industrial minerals, ferrous metal, non-ferrous metal, slag metals, and coal and other fuels.

XRT ore sorting shows promise at Vendetta Mining’s Pegmont project

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Following positive X-ray Transmission (XRT) ore sorting test work on the Pegmont asset, in Queensland, Australia, Vendetta Mining is looking to apply this technology in its next mining study at the lead-zinc project.

The test work, conducted at TOMRA’s testing facility in Sydney, Australia, concluded that the XRT sorters could distinguish between high-density/high-grade feed and lower-density waste material at Pegmont, the company said.

Vendetta said: “At Pegmont, the potential advantages of XRT material sorters is that they could allow plant feed material to be screened prior to grinding and flotation, removing lower density external dilution (waste) and lower-grade internal dilution (material below cutoff).”

Potential capital cost savings occur through the reduced mill throughput while potential operating costs savings occur through reduced water and reagent usage, less pumped tails and lower energy requirements, it said.

The test work envisages that sorted waste product would be ejected and stacked for dry disposal (dry stack tailings).

Vendetta said: “Flotation recovery often improves with increasing head grade. Such a relationship exists in the metallurgical test work performed at Pegmont to date. The higher head grades obtained from the ore sorted product are anticipated to result in enhanced flotation recovery.”

The testing involved material from two drill hole intersections from Zone 5 and one from Zone 2 at Pegmont. The sulphide intersections were selected in order to test different lead to zinc ratios (Zone 5 vs Zone 2) and internal grade distributions, it said. All samples included diluting quartzite material from the hangingwall and footwall.

The conclusions of the XRT ore sorting preliminary test work on the three drill intervals are it can successfully remove the external dilution from the samples; and successfully remove internal diluting material from within the higher-grade intervals.

The total mass tested amounted to 139.2 kg, with the mass pull (weight % of feed recovered) ranging from 44.3% to 70.6% (a weighted average of 62.3%).

The lead grade improved from 18% to 88%, a weighted average of 42%; zinc grade improved from 21% to 72%, a weighted average of 38%; lead recoveries ranged from 83.2% to 90.2%, a weighted average of 88.5%; and zinc recoveries ranged from 76.4% to 92.2%, a weighted average of 85.9%.

Vendetta said that while these results were highly encouraging, they are preliminary. “In order to apply material sorting results in an updated preliminary economic assessment (PEA) study, pilot scale test work is necessary,” the company said.

TOMRA recommends 600 kg of material is required for each ore type at Pegmont. Vendetta plans to pursue this test work and expects these samples will be obtained from the next drilling program. Samples will be obtained from Zone 1 transition, Zone 2-3 sulphide and Zone 5 sulphide.

Michael Williams, President and CEO, said: “At Pegmont, the XRT sorter can clearly differentiate between high density/high grade feed from lower density waste material at Pegmont. We are excited by the prospects of advancing to pilot scale test work and applying this commercially available technology to the next mining study.”

The existing Pegmont PEA contemplated a production rate of 1.1 Mt/y, which corresponds to two TOMRA COM XTR 1200 – generation one ore sorters, Vendetta noted.

Steinert ore sorting tech picks up the Beaton’s Creek gold fine print

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Novo Resources says initial laboratory-scale tests using Steinert mechanical ore sorting technology indicates an upgrade of gold into significantly reduced mass is achievable at the Beaton’s Creek project in Western Australia.

The mechanical sorting tests carried out in Australia on the Beaton’s Creek bulk sample showed that nuggety gold occurring in Beaton’s Creek conglomerates is finer grained (generally sub 1 mm) than gold at Novo’s Egina and Karratha projects (generally over 1 mm), the company said. The company is also considering using ore sorting at these two projects.

Test work was conducted on a 2.8 t split of crushed (-50 mm) and screened Beaton’s Creek bulk sample material, with analyses conducted as part of this sorting test work generating a calculated head grade of 5.72 g/t Au for the bulk sample. The vast majority of gold reported to mechanically sorted concentrates in each of the three size fractions tested, with 90.2% of gold recovered in 54.5% of the mass of the +18/-50 mm fraction; 68.8% of gold recovered in 42.4% of the mass of the +6/-18 mm fraction; and 95.5% of gold recovered in 20.3% of the mass of the +2.3/-6 mm fraction.

Material finer than 2.3 mm, comprising 17% of the total mass of the bulk sample, was not tested due to excessive dust issues, the company said. “Novo believes such material is treatable by means of gravity concentration,” it added.

“Test results are considered indicative, and Novo and Steinert see additional opportunity to optimise sorting conditions and parameters that may result in further efficiencies,” the company said. “Nevertheless, these tests indicate robust potential for upgrading nuggety conglomerate gold mineralisation, and perhaps, a broader spectrum of gold mineralisation types.”

A second 2.8 t split of the same bulk sample material has been delivered to TOMRA Sorting’s mechanical sorting test facility in Castle Hill, New South Wales, where it will soon undergo similar testing using various TOMRA mechanical sorters, the company said.

Rob Humphryson, CEO and Director of Novo Resources, said: “We are highly encouraged by these initial results. We are already fully confident about the outcome of Egina mechanical sorting test work, which demonstrated excellent recoveries into very small concentrates. Our Beaton’s Creek test work is more investigative in nature owing to the finer gold grain size, so to achieve such levels of upgrade in first phase testing is remarkable.”

He added: “Test work is being developed and supervised by Novo staff specialising in mining engineering, metallurgical processing, and importantly, our geology team. This means those people engaged in exploration are fully aware of the profound impact that mechanical sorting potentially imparts on the economic viability of our prospects. Mechanical sorting test work is likely to become an integral part of future exploration and economic modelling as we hopefully progress each of our projects towards production should the economic viability and technical feasibility of the project be established.”

DRA to run the ore sorting numbers at Nova Minerals’ Korbel gold deposit

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Nova Minerals has engaged DRA Global to conduct Phase 1 and 2 ore sorting test work at the Korbel gold deposit, in Alaska, USA.

This work will help continue Nova’s progression of the deposit towards a future low strip, bulk minable, heap leach operation, it said.

This is not the first ore sorting remit the engineering firm has had. Back in November, DRA was instructed by Snow Lake Resources to look into ore sorting options at the Thompson Brothers lithium project, in Manitoba, Canada. Snow Lake Resources was previously spun out of Nova Minerals.

The objective of the study through 2020 is to assess the suitability of sorting applicable to the specific style of mineralisation contained at Korbel. It will also involve test work, design, management and supervision to determine ore sorting amenability. Additionally, the study will assess the overall impact of the ore sorting circuit in a future flowsheet. This will include completion of a dynamic simulation in phase 2 to establish ore sorting stockpile and ore sorting requirements for the optimal capital expenditure (capex), operating expenditure, operability and maintainability of the overall process plant.

High level deliverables will include generation of process mass and water balances, mechanical equipment list, and a concept level (AACE Class 5) capex estimate for the entire plant.

The company said: “Nova recognises the need for sorting studies early on in the mine development cycle. These kinds of studies help to keep moving the project towards prefeasibility.”

In addition, the sorting study will run concurrently with the 2020 resource drilling program. Subject to drilling and positive results, Nova sees various processing options at Korbel. These options include heap leach, carbon-in-pulp (CIP) circuit, or a combination of the two.

Nova Minerals Managing Director, Avi Kimelman, said: “We are very pleased with the progress that the company is making towards delivering on its plan to rapidly unlocking the Estelle Gold District through both significantly increasing resources and fast tracking the Block B ‘Starter Pit’ to development. This sorting test work commencing simultaneously with our drilling maintains our strategy of saving time, resources and money by streamlining data and productivity to deliver strong shareholder returns in as short a timeframe as possible whilst still ensuring that the technical and economic possibilities are fully understood and progressed.”

Kimelman said Nova’s greatest accomplishment in 2019 was proving up 2.5 Moz of gold in the inferred resource category in a very short period of time and demonstrating “exceptional” gold leach recoveries averaging 76% at the Korbel deposit (one of 15 known prospects).

“We look forward to amplifying our exploration and project development efforts in 2020 and are committed to keeping our shareholders constantly updated on our progress.”

Vital moves towards REO production with mining, road construction and ore sorting contracts

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Vital Metals says it has agreed multiple development and supply contracts that will assist it in rapidly becoming North America’s next rare earth mining company.

The ASX listed company’s Cheetah subsidiary has signed preferred mining contractor and ice-road construction contracts for its Nechalacho rare earth project, in the Northwest Territories of Canada, with Det’on Cho Nahanni Construction and Aurora Telecom Services, respectively. These contracts allow for the mobilisation of plant and equipment to site over the winter to enable site establishment works to be completed in preparation for operations to commence in 2020.

In addition to this, it has also issued a purchase order to acquire COM Tertiary X-ray Transmission (XRT) 1220/B ore sorting equipment from TOMRA Sorting Inc for C$1.4 million ($1.07 million).

All three of these moves follow close on the heels of the delivery of a 95 Mt JORC-compliant resource at Nechalacho and positive concentration and hydrometallurgy test work.

Vital Metals Managing Director, Geoff Atkins, said: “The signing of these agreements marks an important milestone in the development of the Nechalacho rare earth project as they provide the foundations for enabling Vital Metals to become a producer of rare earths in 2020 through the processing of material from the North T zone. These contracts and agreements also provide prospective customers with a far greater level of confidence in potential delivery dates to progress offtake negotiations.

“Further, by confirming the use of sensor-based ore sorting technology to produce a concentrate, it will remove the requirement for traditional reagents, process water and tailing facilities used in typical ore beneficiation.”

The decision to acquire the TOMRA ore sorter follows excellent results achieved from the recently completed ore sorting test work that produced a high grade (+35%) concentrate, Vital Metals said.

The COM Tertiary XRT 1220/B ore sorter is the same machine used in test work to produce the high-grade product, it said. The purchase order includes supply, installation, commissioning and spare parts, with delivery of the sorter to Yellowknife scheduled for June 2020.

“The ore sorting test work highlighted that the Nechalacho REO project is one of the few and the first REO project to successfully use ore sorting to produce a high grade +35% REO concentrate without the use of reagents and water,” the company said. “This will substantially reduce the cost and the lead time to bring the Necalacho REO project into production.”

TOMRA XRT leaves its mark on Minsur San Rafael tin mine

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TOMRA Sorting Mining says Peru’s Minsur SA has felt the benefit of its X-ray Transmission (XRT) sensor-based ore sorting technology, with its San Rafael tin mine having seen an increase in reserves, plant capacity, overall recoveries and mine life since it was introduced.

Part of the Breca Group of companies, Minsur owns and operates the largest underground tin mining operation in the world, San Rafael. Located in the Eastern Mountain chain of the Andes in Peru at an altitude of 4,500-5,200 m above sea level, the mine contributed about 6% of the total world production of tin in 2015, with about 1 Mt of ore at an average grade of 2.13% mined and processed, resulting in 20,000 t of tin concentrate.

That same year, Minsur initiated a number of activities to ensure the future value of its asset, addressing challenges that included declining head grades and rising operating costs, according to TOMRA.

One of these activities involved an ore sorting project.

Started in 2015, in collaboration with TOMRA Sorting Mining, the project’s objective was to reject low-grade material in coarse particle size.

“By separating sub-economic material before entering the more cost-intensive wet processing, the project would address the bottleneck at the wet section and improve productivity by increasing the feed grade,” TOMRA explained. An added benefit expected from the project would be the longer life of the mine.

Three main factors indicated that sensor-based particle sorting for waste rejection would be effective at San Rafael:

  • The high absorption of transmitting X-rays of tin contained in cassiterite;
  • The structures of cassiterite, which are large enough to be detected by XRT technology; and
  • The significant degree of liberation of sub-economic waste on the particle level that may be subject to sensor-based particle sorting.

In order to assess the feasibility of the project, TOMRA conducted metallurgical tests on geological samples from San Rafael, followed by performance test work. The tests showed the deposit to be amenable to XRT ore sorting due to the presence of 70-80% of uneconomic particles that can be rejected over a wide size range, from 6 to 70 mm, TOMRA said.

The project was approved and, in view of the significant economic potential, was fast tracked and completed in just 14 months. TOMRA and its partner in Peru, which supplied and installed the XRT sorting system, worked closely with Minsur throughout the six-month ramp-up period.

The ore sorting project with TOMRA’s XRT system has delivered significant financial benefits from the beginning, with Minsur realising payback on its capital expenditure in just four months, according to TOMRA. In 2017, the ore sorting project contributed around 36% of Minsur’s total production with about 6,000 t of tin concentrate, the company said.

The project has reduced capital and operating costs at San Rafael in a number of ways:

  • Added value – TOMRA’s XRT sensor-based ore sorting is converting uneconomic waste material into economic ore, as material below the cutoff for the main plant can be treated with lower operating costs and converted into reserves;
  • Increased plant capacity – The main plant capacity has gone from 2,950 t/d before implementation to 3,200 t/d today, as a result of the crushing operation at the XRT sorting plant;
  • Significant improvement in the overall recovery in the main plant – from 90.5% to 92.5%. This is due to sensor-based ore sorting rejecting particles with very fine mineralised cassiterite that is too small for detection by the XRT system, resulting in higher grade and size of mineralisation;
  • Extended life-of-mine – today, about 24% of the feed to the sensor-based ore sorting plant come from low grade ore from underground, which in the past would have been below the cutoff. This increase in reserves significantly extends the life of mine;
  • Elimination of liabilities through the treatment and proper disposal of 100% of the stockpile; and
  • Decreased tailings disposal due to the sensor-based ore sorting system reducing the amount of waste by increasing the grade in the feed to the plant.

TOMRA concluded on the San Rafael case study: “The success of the project has demonstrated the high potential of TOMRA’s XRT technology, and as a result, the company plans to include XRT sensor-based ore sorting as a possible process route in all future projects.”