Tag Archives: ore sorting

AusTin Mining weighing up ore-sorting at Taronga following positive tests

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TOMRA is continuing to win praise for its sensor-based ore sorting technology, with AusTin Mining being the latest company to say pilot test work indicated the process could remove a significant amount of waste and boost grades.

The company had previously carried out a 60 kg trial with TOMRA on material from the Taronga project in New South Wales, Australia, which indicated X-ray Transmission (XRT) ore sorting was effective.

The latest test work went a step further, with 1.6 t of material grading 0.15% Sn from the Northern Zone of the Taronga deposit being crushed and run through an XRT-1200 sorter in a series of tests for different sizes.

In summary, the latest result indicated:

  • Significant mass rejection (up to 66%) to waste may be achieved. This could either reduce the scale of the downstream processing plant and/or enable an increased plat throughput;
  • Uplift (up to three times) in the grade of sorted product, which could increase the tin units reporting to a downstream processing plant;
  • Increase (over three times) in the grade of fines (-8 mm) material, highlighting the potential for preliminary beneficiation in conjunction with ore sorting, and;
  • Consistent waste grades across all tests, indicating the potential to increase tin recovery with increasing feed grade.

CEO, Peter Williams said of the results: “Aus Tin Mining is encouraged by the benefits ore sorting could deliver for the Taronga tin project, not only including the potential uplift in grade, but also the scope for lower costs and the long-term potential opportunity to exploit more of the mineral resource.”

Williams added that the Stage 1 project at Taronga would provide an “ideal opportunity to test and optimise the technology”.

In 2015, the company announced it would commence a Stage 1 development comprising a 340,000 t trial mine within the Northern Zone ore reserves and pilot processing plant able to produce a saleable concentrate over an 18-24 month period. The company is currently in the process of progressing outstanding regulatory approvals and contractor negotiations for this project.

In the coming weeks, AusTin intends to evaluate whether to proceed with an ore-sorting trial in conjunction with the Stage 1 project, including considerations for additional costs and existing approvals.

“The company will also transport the residual material from the ore-sorting test work to the Granville tin project to assess the material for downstream gravity and flotation processes,” the company said.

The Taronga tin project comprises two major zones of quartz-cassiterite, sheeted vein-style mineralisation. The Northern Zone accounts for approximately 70% of the total mineral resource (27 Mt at 0.15% Sn for 40,100 t contained tin) and is open at depth. The Southern Zone (9.3 Mt at 0.19% Sn for 17,100 t contained tin) comprises a very coarse cassiterite demonstrating superior metallurgical properties plus contains higher tin, copper and silver grades.

Avalon, Cronimet proving sensor-based ore sorting thesis for East Kemptville tin project

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Avalon Advanced Materials has moved a step closer to incorporating sensor-based ore sorting into its plans at the East Kemptville tin project in Nova Scotia, Canada, after the latest testwork came back with positive results.

As recently as July, the company said ore-sorting technology had the potential to upgrade the feed material to the processing plant, thereby reducing both capital and operating costs and the volume of tailings generated, and it has stuck by that assessment after the latest batch of work.

Sensor-based ore-sorting (an example from Outotec shown above) is an emerging technology seeing increasing application in the mining industry. It involves the scanning of individual rock particles on a conveyor using various types of available sensor technologies.

Depending on the chemical, mineralogical or physical characteristics, the particles of value are individually identified and separated from the ‘rejects’ by applying either a mechanical, hydraulic or, in the case of East Kemptville, pneumatic process.

The most recent work, which comes on the back of similar preliminary work in 2017, was conducted by Cronimet Mining Processing, which is providing technical and metallurgical services to Avalon.

Drill core samples from the in-ground resources at East Kemptville were delivered in July to a test facility in Kentucky, US, in order to determine the amenability of East Kemptville tin mineralisation for beneficiation using sorting technology.

Samples varying from relatively high-grade to low-grade tin concentrations were scanned using a multisensory sorter platform. Based on these scans, an algorithm was developed to allow for the separation of the material during tests.

The feedstock used during the test campaign contained 0.11% Sn, 0.06% Cu and 0.11% Zn. The first step of the testwork produced an upgraded product containing 0.47% Sn and a product mass yield of 12%.

Recovery versus grade data also showed ore sorting can be used to recover the zinc ore mineral sphalerite (which also contains indium) from this resource. The zinc-indium feed was successfully upgraded to 0.23% Zn in the first step, while copper content remained low.

Similar positive results were achieved in a preliminary ore sorting test programme conducted in 2017 using material from the low-grade stockpile, Avalon said. This confirms the technology can be successfully employed to upgrade both the in-ground tin resource as well as the stockpiled material.

Based on these results, Cronimet has recommend a detailed sampling campaign be conducted on the low-grade stockpile, followed by an extensive bulk testwork programme using a pilot-scale ore sorting plant to test the recovery of valuable minerals on a pilot scale.

Cronimet will be visiting the East Kemptville site in September to meet with Avalon and site representatives in order to design and schedule the sampling programme likely to involve the extraction of a bulk (circa-10 t) composite sample sometime in October.

The test programme, including writing of the technical report, is expected to take five to six months to complete. This will be combined with a confirmation drilling programme on the stockpile, which will be used to finalise the small-scale site re-development model to the feasibility level of confidence, following which it is contemplated Avalon and Cronimet would enter into a partnership for the joint development of the project.

In July, Cronimet started carrying out the installation of ore sorting equipment at Almonty Industries’ Panasqueira mine in Portugal. This particular installation was aimed at reclaiming coarse fraction tailings and would result in a production increase of about 10%, according to Almomty.

Sotkamo Silver hopes XRT ore sorting technology will lead to upgrade

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Sotkamo Silver is looking to become one of the few precious metal operators using X-ray Transmission (XRT) ore sorting technology at its project in Kainuu, central Finland.

The project, which IM visited as part of the Finland Mine Safari for analysts and investors organised by Mining Finland this week, is expected to start production in the March quarter, ramping up to initial capacity of 350,000-450,000 t/y from a combined open-pit and underground operation.

At this rate, the mine should produce some 1.1 Moz/y of payable silver over a seven year life at all-in cash cost of around $9/oz, along with significant amounts of zinc, lead and gold within three saleable concentrates (Ag-Au-Pb, Zn-Ag and pyrite-Ag).

In order to cut processing costs and improve grades, Sotkamo is looking to install an Outotec-TOMRA XRT ore sorter at the operation. The machine, which will be acquired through a low interest loan from a Business Finland subsidiary, will be used after two-stage crushing (jaw and cone crushers) has taken place and the rock is some 30-70 mm in size.

Test work in 2015 on some 2,200 kg of Sotkamo samples showed the silver content from low-grade ore  increased some 1.9x to 116 g/t Ag, while the average silver content in ore was boosted 1.43x to 195 g/t Ag. Silver recovery from low-grade ore samples was 88%, while average ore-grade recoveries were 89%.

In addition to this, about 60% of the rock previously classified as low-grade ore was removed as gangue with the XRT trial at TOMRA’s facility in Germany, with some 43% of rock reporting as gangue from the average grade ore samples.

CEO Dr Timo Lindborg said the sorting technology did not locate the silver within the ore, but recognised lead. This would enable the company to upgrade the silver grade within ore reporting to subsequent grinding, flotation and filtration processes.

During the site visit, IM saw the mill building being constructed, witnessed pre-stripping of the openpit and works on the tailings facility, and saw the already-completed decline down to 350 m depth.

The company is currently in the process of selecting a mining contractor to carry out both openpit (conventional truck and shovel) and underground (longitudinal bench and fill, using cemented backfill where necessary) works.

The 2017 technical report envisaged using electric-hydraulic production drilling jumbos, diesel LHDs (remote controlled where possible) and diesel dump trucks underground for mining the 20 m high, 60-70 m long and 5-30 m wide stopes, along with backhoe excavators and articulated or dump trucks for open-pit mining.

Sotkamo Silver expects to extend the 2.6 km-long decline, which was constructed by Outokumpu back in 1993, down to the 750 m level in year three, while it is also weighing up the use of both solar and wind power at the operation further down the line.

Agnico Eagle Mines looks to roll out innovation across its operations

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Automation, ore sorting, continuous mining and renewable energy solutions are all being examined by Agnico Eagle Mines as the company looks to the future of its gold operations in Canada, Finland and Mexico.

The company is already in the process of installing a Long Term Evolution (LTE) network at its La Ronde Zone 5 (LZ5) project in northwestern Quebec, Canada, which will be rolled out with an autonomous loading and hauling pilot later this. This will make LaRonde the first operation to use Sandvik’s AutoMine® system with an LTE communication network underground on a production scale.

In a company update this week, Agnico Eagle said two production trucks, one scooptram and the required material for automated mining at LZ5 were expected to be on site this quarter and testing was expected to take place in the December quarter. Sandvik originally said it would provide one LH517 17 t LHD and one TH551i 51 t haul truck as part of the initial pilot.

Now, even before the pilot has started, Agnico has said it is examining the potential to use the same LTE infrastructure as part of an automated loading and hauling solution at its La Ronde Zone 3 (LZ3) project.

LZ3 is envisaged as a phased development that could extend mining at La Ronde from 3.1 km to 3.5 km below ground and provide two or three additional production levels through 2022.

At the same time as this, representatives from Agnico Eagle Finland said on a site visit to the Kittilä gold mine in the north of the country – organised as part of the Finland Mine Safari tour for analysts and investors – that the company was weighing up autonomous hauling and loading solutions as part of the €160 million ($185 million) expansion to increase production capacity at the mine to 2 Mt/y by 2021.

With Kittilä set to go down to around 1.15 km below ground and mining due to take place in four distinct zones as part of this expansion, an LTE network will most probably be required for effective use of this technology.

And, this is not all in terms of technology and innovation at Agnico Eagle.

In its latest corporate update, the company said it was evaluating the use of Rail-Veyor technology at its mines across the group. A 3 km underground Rail-Veyor system is already hauling tonnes at the Goldex operation in Quebec.

And, Agnico is preparing to implement a pilot plant for ore sorting technology to potentially boost low-grade ore, while it is closely following a technology pilot for mechanical cutting.

Lastly, the company said it is looking at renewable energy solutions for its operations in Mexico and Nunavut, Canada.

This is part of a global approach to reduce energy costs at select regions by up to 30% and lower greenhouse gas emission, Agnico said.

The areas of study in Nunavut, where the company is currently building out a major production hub, include wind and solar power, the use of LNG and potential hydro options. The power solutions are also likely to include some sort of battery storage.

In Mexico, meanwhile, where the company operates its Pinos Altos gold mine, it is looking to solar power as a way of cutting its greenhouse gas emissions.

MineSense welcomes ABB unit to register in latest equity financing

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Caterpillar, Mitsubishi Corp and ABB Technology Ventures have bought into MineSense Technologies’ real-time, sensor-based ore data and sorting solutions for large-scale mines in its latest equity raising.

The $18 million oversubscribed financing will be used to help commercialise the company’s digital offering and expand into key mining regions worldwide, MineSense said.

MineSense calls itself a pioneer in Industrial Internet of Things solutions, with its fast, scalable, and robust mineral sensing platform creating “transformational value by providing precise, accurate, real-time grade control and ore routing decisions at the point of extraction for maximum resource conversion and metal recovery”.

This technology can also reduce CO2 emissions and the consumption of wear materials, energy, water and reagents during the whole mining process, according to the company.

This is the second time Cat has invested in MineSense, with Cat’s Director of Mining Technology, Jim Hawkins, saying such technology could have a significant impact on the bottom line for mining companies.

“We are very pleased with the progress MineSense has made in the last 18 months to introduce its innovative technology and are excited to support the company into the next stage,” he said.

Mitsubishi Corp has provided support to MineSense since its late 2017 $4 million debt investment, converted to equity in this round, while this is a first investment for ABB’s strategic venture capital unit.

Brandon Spencer, Managing Director of Business Unit Process Industries at ABB, said the company was excited by the direct impact the MineSense technology may provide to its customers.

The financing also included existing investors Aurus Ventures, Chrysalix Venture Capital and Cycle Capital.

The British Columbia-based company says its system is the only one that can work with run-of-mine at “commercially relevant throughput”.

The MineSense ShovelSense™ system is designed for extreme environment conditions and to be easily retrofittable on any existing mobile equipment. The system comes equipped with a human machine interface that provides the operator with full information, including the ore type, within each dig cycle. It can also connect directly to fleet management or other existing control software systems.

The main application of ShovelSense is at the open-pit dig face or underground hauling point. It is equally effective working in stockpiles and in blending where mobile equipment is used, MineSense says.

Teck partnered with MineSense for the first full scale trial of the bucket-mounted ShovelSense technology in 2017 at its Highland Valley Copper Operations in British Columbia. The sensors are now in use on one shovel, and additional shovels could be considered for later in 2018.

MineSense’s BeltSense™ system can be operated in bulk, semi-bulk or particle sorting mode. Its typical use is post primary crushing prior to the mill, but it also has mill applications such as in the pebble circuit. BeltSense is also highly effective in blending operations, according to the company.

BeltSense can be used sequentially and in conjunction with ShovelSense to maximise the ore concentrating impact, taking a first cut at the haul point and second further downstream.

In addition to this recent financing, MineSense closed a $19 million equity deal in February 2017.

Two Mile Hill underground mine concept a step closer following ore sorting trials

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The stage two ore sorting campaign on drill core from Middle Island Resources’ Two Mile Hill tonalite gold deposit in Western Australia has confirmed the technology’s potential to improve gold grades and cut waste processing.

Two Mile Hill, part of the wider Sandstone gold project, comprises a “ubiquitously gold mineralised, tonalite (granite) plug or stock”. At surface, the deposit measures some 250 m in length, 80-90 m width and extends to at least 700 m depth. It is some 4km north of the company’s 600,000 tonne per year Sandstone processing plant.

Middle Island has been looking for ways to improve the economics of mining the deposit through the use of ore sorting technology. This followed recognition that more than 96% of the gold at Two Mile hill was hosted by quartz veins within the tonalite. The deposit hosts 391,000 ounces of gold inferred resources grading 1.35 grams per tonne, according to a 2004 JORC study.

Stage one trials, using X-ray and optical sensors, indicated sorting could deliver a 185-257% increase in feed grade, with gold recoveries in excess of 93%. Up to 64% of the sorter feed material could be rejected, delivering significant economic benefits.

While stage one focused on the concept of selective underground mining with open stoping – therefore, using diamond core intervals with a higher head grade – the latest trials envisaged sub-level caving and took into account core that was representative of the entire sample.

A series of four primary (fresh) composites and a single transitional (partially oxidised) composite comprising intervals of half HQ and half PQ diamond core from hole MSDD261 were selected for crushing prior to ore sorting.

The results from stage two trials, which involved initial sighter and scoping tests at both Steinert in Perth and TOMRA in Sydney before moving onto the latter’s commercial scale sorting equipment and a combination of colour and X-ray sensors, were “broadly in line with the earlier scoping trials”, Middle Island said.

Sorting of the primary composites (A, B and C) resulted in upgrades to the sorted concentrate in the range of 155-213%, with the majority of gold selected by way of colour differentiation. Sorting recoveries for primary composites ranged from 67-93%, while sorting yields (percentage of feed reporting to product) ranged from 39-51%.

Middle Island said: “Recoveries and yields are variable, and somewhat lower than demonstrated in the preliminary work, in part due to the higher proportion of fines generates by crushing the larger diameter core and in part by weaker oxidation and associated iron-staining in material comprising Primary Composite A.”

These results are a precursor to an updated resource estimate for the upper half of the 0.9-1.5 million ounce exploration target at Two Mile Hill and an underground mining study.

The company thinks further work is needed to ascertain the factors that give rise to the variance in recoveries between the samples, with stage three ore sorting testwork likely focusing on these aspects and anticipated enhancements using TOMRA’s recently commissioned, commercial-scale, laser sorting unit.

Almaden puts TOMRA XRT ore sorters to the test

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X-ray Transmission (XRT) ore sorting looks to be catching on in mining, with Vancouver-based Almaden Minerals the latest company to put the technology to the test.

Almaden, which is the majority owner of the Ixtaca gold-silver project in Puebla state, Mexico, recently engaged TOMRA Sorting Solutions to run a 2,200 kg sample of material from the project through a commercial scale XRT machine in Germany and the results speak for themselves.

The limestone sample, collected from fresh drill core in the Ixtaca Main zone, was crushed and screened at a McClelland metallurgical lab in Reno, US, and shipped to TOMRA in Wedel, Germany.

The results of the tests showed XRT could successfully reject 39% of waste rock from coarse rock (18-50 mm) at grades of 0.25 g/t Au and 12 g/t Ag, and 52% of waste rock from mid-size rock (12-16 mm) at grades of 0.22 g/t Au and 12 g/t Ag. These grades were below the anticipated mine cutoff grades, but Almaden was able to elaborate further on the impact.

The results showed including conventional XRT ore sorting technology could:

  • Increase average mill feed grades for the limestone unit by 39% for gold and 47% for silver
  • Push the average annual metal production above the 147,900 ounces per year of gold-equivalent envisaged in Almaden’s 2017 pre-feasibility study
  • Bolster the initial rate of return and payback economics of the project
  • Reject 36% of run of mine as waste rock at the crushing stage
  • Produce a 93% recovery for silver and 88% recovery for gold from the ore sorter
  • Reduce the environmental footprint over the life of mine by:
    • Reducing process tailings
    • Lowering process water usage
    • Cutting process energy requirements and CO2 emissions.

And, these benefits came with only a “modest impact on capital costs”, Almaden said.

XRT is becoming more prevalent in mining with several recent installations in gold, diamond and tin operations.

Morgan Poliquin, President and CEO of Almaden, said the Ixtaca deposit was particularly well suited to the technology as the occurrence of gold and silver in the limestone-hosted portions of the project is in the form of high-grade veins and veinlets that “branch and re-connect, as well as locally change strike and dip, pinch and swell”.

This can result in wireframe models that contain interspersed irregular zones of barren limestone host rock, leading to dilution.

The broad-band radiation that comes with sensor-based ore sorting and penetrates the crushed and screened mineralised rock can see beyond this and ‘reject’ what would be considered waste rock from further processing (see below graphic, credit: TOMRA).

The TOMRA test work will now go into the company’s feasibility study at Ixtaca, which is expected to be completed this year.

In the meantime, another precious metals focused company has already gone ahead and installed a commercial XRT unit in its operation.

Pantoro, in its June quarter production results, confirmed a Steinert XRT ore sorter was installed and commissioned at its Halls Creek gold mine in the Kimberley region of Western Australia.

Pantoro said: “The ore sorter will be the primary facilitator of continued production increases during the coming year. The full benefit will be achieved from the ore sorter as ore development and production from the Wagtail underground mine ramps up.”

The company is aiming for production rates of 80,000-100,000 oz/y by the end of 2018 as the ore sorter and Nicholsons process plant become fully utilised. The company produced 52,203 oz of gold in the 12 months to the end of June.

TOMRA XRT ore sorter goes to work at Renison tin mine

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Metals X and its joint venture partner Yunnan Tin have commenced commissioning of its new crushing and ore sorting facility at the Renison tin mine in Tasmania, Australia.

The ore sorting equipment, provided by TOMRA, is expected to increase annual tin production at Renison by 15-20%, according to Metals X.

Underground ore production at the 50:50 owned Bluestone Mines Tasmania JV is expected to increase to approximately 920,000 tonnes per year, while maintaining the processing plant at some 720,000 t/y.

The TOMRA X-Ray transmission ore sorter will reject an estimated 200,000 t/y of waste at the crushing stage, upgrading the ore before the processing plant.

In preparation for the introduction of ore sorting, additional areas within the underground mine have been developed, production rates have been increased and a significant surface stockpile of ore accumulated.

The purpose-built three stage crushing, screening and ore sorting plant has been constructed at a capital cost of some A$15 million. The payback is estimated to be less than 10 months at current tin prices.

With the commissioning of the ore sorter and the new tails dam already in operation, the major capital expenditure programme at Renison is complete.

“The operation is now set up for the long term future, with increased production capacity and additional flexibility to allow the … JV to exploit the large resource base at Renison,” Metals X said.

XRT sorting technology is increasingly being used in the mining sector in order to reduce the amount of waste processed through the comminution circuit. This, then, boosts the overall ore grade.