Tag Archives: ore sorting

CRC ORE and Canada’s NRC to move LIBS mineral analysis to the mine site

The Cooperative Research Centre for Optimising Resource Extraction (CRC ORE) and the National Research Council of Canada (NRC) have partnered on a project to bring the benefits of laser-induced breakdown spectroscopy (LIBS) chemical element analysis to the mine site.

LIBS, a rapid chemical element analysis technique, is used in a variety of applications including analysis of soil, effluents, scrap metal, alloy and molten metals. It works through a focused laser pulse striking the sample surface and removing an amount of material to generate a high-temperature plasma plume. Atoms and ions are excited to higher energy levels and, while returning into their ground state, emit characteristic energy signatures for each element.

The robustness of LIBS is well suited for real-time minerology analysis and at all stages of the mining production cycle, according to CRC ORE, with commercially available laboratory-based quantitative mineral analysers (QMA) – such as QEMSCAN and MLA – historically used in mining.

“However, these technologies are not suited for in-stream or on-belt applications due to their meticulous sample preparation and measurement protocols,” the centre said. The analysis is limited to costly lab-based sampling, which requires the extraction of extensive samples and the transport of these to lab facilities, sometimes many hundreds of kilometres away from the mine site, according to CRC ORE.

To provide a timelier solution to the mining industry, the CRC is working with the NRC to explore the use of LIBS sensor technology for applications such as mineral characterisation across a conveyor belt. Additionally, the use of LIBS is being examined as an industrialised elemental and mineralogical analyser for scanning coarse rock streams.

CRC ORE Program Coordinator, Dr Greg Wilkie, said the two organisations are taking LIBS use in the mining industry to the next level by putting the technique to use in operating mine sites.

“By applying LIBS in a real-time application, such as across an operating conveyor belt, operators are empowered with high volumes of rapid analysis provided in real time,” Dr Wilkie said. “Analysis in real time speeds up the mineralogy process, providing operators with detail they may have previously had to wait days or weeks to obtain.”

He added: “We are proudly putting the minerology back into process minerology.”

The NRC’s Senior Research Officer, Dr Alain Blouin, said the NRC and CRC ORE are working on a long-term LIBS project, which is nearing the end of an intensive two-year study.

“We are developing a novel application of a LIBS rapid on-line mineralogical characterisation instrument suitable for deployment on mine sites,” Dr Blouin said. “LIBS can measure a large number of elements simultaneously with the ability to detect light elements beyond the capability of many other techniques.”

Dr Wilkie said since LIBS can perform analysis several metres away from what it is measuring and still detect extremely low concentrations it is well suited technology for the mining industry.

“Beyond cross-belt scanning, LIBS can work in a variety of settings from in-pit muckpiles, underground draw points and on-line slurries,” Dr Wilkie said.

It is anticipated that the real-time LIBS solution be used in conjunction with CRC ORE’s Grade Engineering® – an approach to the early separation of ore from waste material. Grade Engineering is minimising the impact of declining grades and productivity in the Australian and global minerals sector, according to CRC ORE.

NextOre’s ore sorting tech shows potential at Magnetite Mines’ Razorback project

Magnetite Mines Ltd says a study looking at applying NextOre’s on-belt magnetic resonance ore sorting solution at its Razorback Iron project, in South Australia, has shown the potential for a significant increase in plant throughput at the asset.

The ASX-listed company said results to date indicated that Razorback ores are especially well suited to bulk ore sorting with substantial improvements to ore mass recovery demonstrated in the study, completed by NextOre (a partnership between CSIRO and industry players Advisian and RFC Ambrian).

NextOre’s solution uses an on-conveyor magnetic resonance sensor to continually sense the grade of the material on the belt. This information is used to control a diverter gate that separates material above the selected cutoff grade (accepted material) from material below that grade (rejected material).

Magnetite Mines and NextOre, in October, signed an agreement that allows the development company exclusivity over any magnetite processing applications, Australia-wide, and all iron ore applications in the Braemar (including New South Wales) for a period of four years.

NextOre’s Razorback report demonstrates that the heterogeneity of the Razorback and Iron Peak resources allows for the potential for significant upgrading from ore sorting, Magnetite Mines said.

“For example, at a 50% rejection level (corresponding to a cutoff grade of approximately 16% Fe at Iron Peak and 14% Fe at Razorback), the grade of the accepted material would be increased by a factor of about 1.4,” the company said.

Were this to be implemented as part of a development of the project, by increasing mining rates, and pre-concentrating the plant feed, the throughput of a given plant capacity could be increased by some 40%, the company said. This would create significant savings in capital and operating costs per tonne of concentrate product, it added.

In order to assess the potential for bulk ore sorting at Razorback, NextOre used data drawn from the overall geological model for the Razorback and Iron Peak resources (the two resources that make up the Razorback project). The Razorback project currently has an inferred and indicated resource of 2,732 Mt at a grade of 18.2% Fe, but Magnetite Mines intends to produce a 68.8% Fe concentrate from the project.

NextOre then applied a fractal model, applying a mixing model to assess the predicted grade variation or heterogeneity of ‘pods’ of ore as they would present to an on-conveyor bulk ore sorting implementation, Magnetite Mines explained. Various sorting cutoff grades were selected to demonstrate a range of grade improvement scenarios, the company noted.

Magnetite Mines said: “Following the recently completed scoping study for a low capital cost, staged development of the Razorback project resources, this study highlights the applicability of NextOre’s magnetic resonance bulk ore sorting technology to the processing of the Razorback ores.

“When applied to a large, heterogeneous, low strip ratio deposit, such as Razorback, bulk ore sorting represents a pre-concentration technology ahead of the concentrator that can enhance throughput, improve economic efficiency and reduce tailings and water use.”

Magnetite Mines Chairman, Peter Schubert, said: “While our scoping study results for a low capital, staged development have been highly encouraging, we are now confident that the use of leading edge ore sorting technology can further enhance results, providing the company with a sustainable competitive advantage.”

Hastings, TOMRA see potential for XRT ore sorting at Yangibana rare earths project

TOMRA’s X-ray Transmission (XRT) ore sorting innovation has another positive industry reference to hand after Hastings Technology Metals said off-the-shelf technology had proven extremely effective at removing dilution on samples used in the testing program at its Yangibana rare earths project in Western Australia.

Testing on a 1.8 t sorted bulk sample had seen a 95.1% recovery of contained Nd2O3+Pr6O11 (neodymium and praseodymium), a 52% increase in head grade from 0.71% to 1.08% Nd2O3+Pr6O11, and a 37.1% mass rejection, Hastings said.

This shows XRT technology could be applied to separate out a barren waste stream from the ore, according to the ASX-listed company, presenting an opportunity to remove waste dilution material from the mining process before the material is fed into the processing plant – resulting in energy and reagent savings in the beneficiation circuit.

The testing involved the crushed bulk ore sample of 1.8 t being screened into two size fractions (10.5 mm) and (plus-10.5mm), with the sortable fraction (plus-10.5 mm)after being diluted with waste material at either 35% or 60% proportions screened on a TOMRA commercial sorter using XRT technology at 32 t/h feed rate.

In the base case, sorted ore samples, crushed and screened to plus-10.5 mm and diluted with 35% waste material, a total of 37.1% of the sample mass was rejected at a grade of 0.09%Nd2O3+Pr6O11, representing a loss of Nd2O3+Pr6O11 of just 4.9%, or an overall recovery of 95.1%Nd2O3+Pr6O11 in the ore. A corresponding 52% increase or upgrade in the ore head grade was achieved from 0.71% to 1.08% Nd2O3+Pr6O11.

In the sorted sample diluted with 60% waste material, the ore sorting test work program achieved an upgrade factor of 2.16 taking the feed grade from 0.43% Nd2O3+Pr6O11 to 0.93%Nd2O3+Pr6O11, while recovering 90.6% of the Nd2O3+Pr6O11, the company said.

Hasting said: “The full opportunity for including ore sorting technology into the Yangibana process flowsheet is still being assessed. Based on these test work results, technical and engineering programs will continue to investigate the benefits that can be realised across the project.”

The proposed beneficiation and hydro metallurgy processing plant at Yangibana will treat rare earths deposits, predominantly monazite, hosting high neodymium and praseodymium contents to produce a mixed rare earths carbonate that will be further refined into individual rare earth oxides at processing plants overseas, according to Hastings.

A definitive feasibility study in 2017, based on a 5.15 Mt reserve, detailed a production rate of 1 Mt/y to produce up to 15,000 t/y of mixed rare earths carbonate at Yangibana.

Snow Lake, DRA and Steinert investigate ore sorting at lithium project

Snow Lake Resources is the latest company to eye up ore sorting to reduce costs and increase productivity, with the exploration company asking DRA Global to come up with an effective strategy for its Thompson Brothers lithium project, in Manitoba, Canada.

Brent Hilscher of DRA will be in charge of this ore sorting project, examining the best laser or X-ray method to help separate out waste material from the spodumene pegmatite at Thompson Brothers, thereby increasing the overall grade of the final product at a low cost per tonne.

Snow Lake has collected 120 scoping samples from the company’s drill core library as part of this test work, with these samples to be sent to Steinert in Kentucky, USA, for analysis.

The company also created four bench test “bulk samples” from the existing core library, which will be used as trial material at Steinert on a full-scale ore-sorting machine once DRA Global concludes the appropriate algorithm for sorting, it said.

As part of the ore-sorting strategy, the company says it will need a higher degree of understanding of the mineral assemblage of the spodumene pegmatites at its project.

The company has, so far, collected nine core samples from the company’s core library and left them with the Saskatchewan Research Council (SRC) in Saskatoon, Canada. These samples will go through QEM-SCAN petrography analysis at SRC, providing DRA with a report on the mineral assemblage of the pegmatite.

From the nine samples, the company will select three samples for microprobe analysis of the various mineral phase.

Snow Lake said: “These studies will give the company an understanding of the mineral chemistry of the feldspar phases. This will help support the X-ray sorting works, as there may be a chemical element that the X-ray sorter can focus on to eliminate the feldspars from the spodumene pegmatite feed.”

As part of a bulk sample program for 2020, the company will also provide samples to SRC to conduct acid–base accounting testing to help assess the acid-producing and acid-neutralising potential of rocks prior to large-scale excavations at the project.

Snow Lake is expecting to publish a maiden indicated resource on the Thompson Brothers project in the near term, given that the company, its consultants and external laboratories have all the data in hand for the study.

Magnetite Mines and NextOre sign ore sorting exclusivity pact

Magnetite Mines Ltd says it has entered into an exclusivity agreement with ore sorting technology company NextOre to use its leading-edge magnetic resonance ore sorting technology for pre-concentration of magnetite and iron ore projects.

The terms of the agreement include exclusive use for any magnetite processing applications Australia-wide and all iron ore applications in the Braemar (including New South Wales) for a period of four years.

Formed in 2017 by RFC Ambrian, Advisian Digital and the CSIRO, NextOre aims to commercialise magnetic resonance ore sorting technology, an on-belt mineral sensing technology developed by the CSIRO. The technology uses a magnetic resonance analyser (MRA), a form of radio frequency spectroscopy, for the quantitative measurement of target ore minerals.

The use of the MRA allows for a high throughput, high accuracy bulk sorting application that is typically added to the front-end of a processing flow sheet to divert waste ores away before processing, according to Magnetite Mines. “This has the effect of improving mining grades by pre-concentrating the ore that will be subject to processing, whilst rejecting significant tonnages of low-grade material to tailings via a diversion method such as a chute flop gate or dead box diverter.”

The theorised result of ore sorting is a reduced volume of upgraded ore that performs better in the processing plant while reducing processing costs as nil-value material that would ordinarily be subject to downstream processing is rejected early on, according to the company.

“Unlike traditional ore sorting technologies that are based on X-ray or infra-red transmission, NextOre’s on-belt MRA ore sorting solution allows for the grade of high throughput ore to be measured at industry-leading accuracies and speeds. Due to the high speed of the technology, the integrative system is able to perform the analysis, computation and physical diversion of waste ores down to 1 second intervals allowing for fast diversion or high resolution sorting.”

Magnetite Mines Chairman, Peter Schubert, said: “We see great potential for technology to unlock a step change in competitiveness of our Razorback iron project (pictured). NextOre has completed an initial mathematical assessment based on our extensive geological data and the results are encouraging.”

Schubert said the company was moving to bulk test work to prove its application in its Razorback iron project, which has generated some 3,900 Mt of iron ore resources and has over 110 km of unexplored strike. The company believes it will be able to produce a 68.8% Fe concentrate from the project.

He added: “NextOre’s magnetic resonance sorting technology, developed over many years in conjunction with the CSIRO, has a rapid response time allowing unprecedented selection accuracy and speed.

“The result is a substantial increase in the head grade of plant feed, resulting in lower unit operating costs and a significant improvement in capital efficiency. But the application of this technology also gives environmental benefits, with enhanced water efficiency and lower tailings levels.”

Razorback already has advantages of scale, proximity to established ports, proximity to rail and shallow stripping, according to Schubert, “but the NextOre technology takes the competitiveness of the resource to another level”.

The company has initiated a desktop study of NextOre’s ore sorting solution with initial results to-date being very positive, it said.

Initial analysis of the macro-scale heterogeneity of the Razorback iron project JORC 2012 mineral resources indicates that the orebodies are suited to the application of ore sorting.

“The highly selective technology is particularly well suited to magnetite measurement and can be calibrated for several mineral types,” it said. “Further test work is envisaged in the near future in aid of refining the existing flowsheet.”

Chris Beal, CEO of NextOre, said: “The Braemar Province is really an astonishingly vast mineralogical system and represents an incredible potential for value. Owing in large part to the way nature arranged its geology, the system appears particularly well suited to the application of bulk ore sorting systems.

“In terms of reductions in water and electricity consumption, tailings dam size reductions, and overall plant efficiencies, the application of bulk ore sorting has the potential to impact developments in the region in a significant way.”

Vista Gold sorts Mt Todd ore processing issues with TOMRA’s XRT technology

Vista Gold has turned to TOMRA Sorting Mining’s ore sorting technology to reignite the Mt Todd gold project, in the Northern Territory of Australia.

Mt Todd, which was acquired in 2006, hosts one of the country’s biggest undeveloped gold resources. A recently completed prefeasibility study outlined a 50,000 t/d operation producing 413,400 oz/y of gold over the 13-year mine life at Mt Todd, with average all-in sustaining costs of $746/oz.

Mt Todd briefly operated in the 1990s, but is known for having hard ore that can prove tricky when finding an efficient processing route.

Fred Earnest (pictured below), President and CEO of Vista Gold, said: “We had a desire to find a way to only be spending money to process the rock that had gold in it. We started looking for ways that we could get rid of the non-mineralised host rock prior to the grinding circuit.”

The company looked at different technologies to address the issues at Mt Todd and contacted TOMRA to find out about its sensor-based sorting technology, Earnest said.

TOMRA invited the Vista Gold team to visit its testing facility in Germany with a sample from the project to see first-hand what could be achieved, TOMRA said.

The test was an eye opener for Fred Earnest, according to the technology company: “In every evaluation of new technology, we have ‘aha moments’. For us it was the day we were at the facility in Germany watching our rock be sorted on a production-scale machine. When we saw how fast it was happening, when we saw the product sorted and rejected, and when we were able to pick it up and look at it – we realised that this was not just a dream, this was real technology being applied at a production rate to our rock.

“All of a sudden, we realised that this was technology that would work for us at Mt Todd and that we needed to evaluate more seriously.”

Following extensive testing, Vista Gold has integrated TOMRA’s two-stage sorting solution in its planned flowsheet at Mt Todd: the system sorts 20 t/h, using X-ray Transmission (XRT) technology to remove particles containing sulphide minerals and subsequently lasers to remove particles containing quartz and calcite.

The benefits of TOMRA’s solution to the Mt Todd project are two-fold, according to the company.
On the one hand, operating costs have been reduced: “We’re getting rid of material and we’re not spending money grinding rock that has no value,” Earnest explains. On the other hand, gold recovery has improved: “We’ve been able to make design changes in the plant. Because we’re processing less material, we’re now able to do a finer size. With finer grind, our gold recovery has gone up. This has resulted in improvements of grade by 10%. Our feed grade to the mill has gone up from 0.84 g/t to now 0.91g/t.”

What’s more, the savings in operating costs have paid for the improvements to the plant, according to TOMRA.

Earnest said: “We’ve been able to achieve all of this on a capital-neutral basis. We’ve been able to incorporate the equipment for the sorting to add fine grinding equipment, all with the money that we’ve saved from the ball mills.

“And, so ore sorting has opened up a whole new window of opportunity for us with the Mt Todd project. We’re very excited about what this technology means to the mining industry and specifically to our projects in the future. And we look forward to seeing this technology grow and become even more efficient and of greater value to us.”

TOMRA says it worked closely with Vista Gold’s team to identify the best solution for the Mt Todd project – from testing rock from the mine at its facility in Germany, to analysing the situation at the project and advising on how its sensor-based sorting technology could fit in its operation to deliver the best results.

Earnest added: “We have been thoroughly impressed with the team at TOMRA. We’ve done a number of tests with them, we’ve worked with them closely. The people at the [testing] facility in Germany have been very accommodating. We’ve been able to be there on the floor, watching the test, looking at the results, asking questions. It’s helped us immensely to have this open exchange with the team at TOMRA and we look forward to a very long relationship with them.”

De Beers diamond XRF technology optimises sorting at emerald mine

De Beers Group Technology has adapted one of its X-ray fluorescence (XRF) diamond sorting range of machines to create “a secure and efficient sorting solution for emeralds”, it says.

According to De Beers Group Technology head, Gordon Taylor, the company’s sorting technologies have been applied to a range of minerals apart from diamonds, and these include gemstones like rubies to lower value commodities like manganese and coal.

“We are always on the look-out for new applications for our sorting equipment, which also employ X-ray luminescence, X-ray transmission, laser, magnetics and ultra-violet technologies,” Taylor said.

“So, we were excited by the opportunity to collaborate with Magnum Mining and Exploration on their Gravelotte emerald project in Limpopo province.”

In its trial mining and processing phase, Gravelotte has been gathering data to confirm the historic grades previously recovered at the project. In operation for much of the 20th century, total recorded production from this area was estimated at nearly 113 Mct. It was reportedly the world’s largest emerald mine of its type in the 1960s, employing over 400 sorters, De Beers said.

General Manager of Operations at Gravelotte, Wessel Marais, said the traditional manual method of sorting carried an associated security risk and led to less than optimal recoveries.

“Various mechanical sorting options are available on the market today,” Marais said, “and Magnum approached De Beers Group Technology to determine whether their diamond sorting technology could be adapted to emerald sorting.”

He says testing of samples provided by Magnum came out with successful results.

“This led to Magnum leasing an XRF machine from De Beers Group Technology for the duration of our trial mining, and the results to date have been very encouraging,” he says. “With the machines now deployed in the operational environment, research and development work is continuing in conjunction with De Beers Group Technology to refine the process.”

Taylor noted that constructive collaboration with customers is often an important element in extending the application of De Beers Group Technology’s equipment.

“On this project, we were able to conduct some fundamental investigation on the properties of emeralds to guide us in developing the most effective solution,” he said.

The De Beers Group Technology emerald sorting machine can make a potentially significant contribution to the success of the Gravelotte operation, according to De Beers, with its high recoveries combined with excellent processing security. The project aims to reach a target of around 3 Mct/y as its initial production rate.

Before the run-of-mine material reaches the De Beers Group Technology XRF machine, it is crushed to -30 mm and put through a trommel screen for cleaning and further size reduction. After material containing emeralds is ejected from the material stream by the sorter, it is further sorted by hand and graded.

“De Beers Group Technology is constantly pushing the boundaries where our equipment can be applied and has had significant successes in non-diamond commodities. Whether removing the value product or the waste from the process stream, our sorting technologies can be the game-changer in the viability of many projects,” Taylor concluded.

Mine sites testing out CSIRO, Mining3’s precision mining concept

CSIRO and Mining3’s wide-ranging precision mining concept looks to be gaining momentum with multiple mining companies testing out aspects of this innovative notion to reduce the footprint of future mine sites.

Among the headlines from the organisations’ latest report on this technology was its ore sorting technology, NextOre, has three trials underway at mine sites, with up to three more systems to be delivered this year.

A Chilean copper mine is testing up to 10 types of sensors, complementing other recent trials in Australia and CSIRO desktop studies. Another study found that a mining company could make the same profit as it is now, but with a 30% reduction in capital and operating costs.

In this pursuit, the mining industry can learn a lot from medical science, according to CSIRO Research Director in Precision Mining and Mining3 Research Leader, Ewan Sellers.

As the CSIRO rock mechanics specialist says, modern medicine has used technology to better understand and treat illnesses and injuries while reducing the impact on people. Sellers is now working towards creating low impact “zero entry mines”.

CSIRO explains: “Precision mining is the industry’s version of keyhole surgery. Once a deposit is discovered, precision mining aims to target the ore and extract the deposit as economically and sustainably as possible.”

CSIRO and Mining3’s shared vision is for mines of the future to be mostly underground, remotely operated by robotics, with minimal or remote offices and a very small environmental footprint. All waste would be used to make other products.

Sellers believes this vision could become a reality for most mines within 20 years, as vast mining operations that leave large scars are consigned to history.

Minerals 4D

Key to enabling precision mining is a concept CSIRO is leading called Minerals 4D.

Minerals 4D ‘intelligence’ aims to image minerals in the subsurface and predict their distribution. By integrating sensors and specialised imaging techniques tied with data analysis and machine learning, miners can better understand the orebody and quantify the rock mass at multiple scales.

Precise cutting, blasting and in-mine processing techniques can then accurately target the ore and leave the waste behind. Miners can focus on the most economic part of the deposit, reducing the need to move, crush and process massive amounts of rock, saving significant amounts of energy, water and waste.

CSIRO said: “Although information about the grade of the material and type of rock may currently be known over a block or at mine scale, Minerals 4D aims to add information about the mineralogy at a much smaller scale. This will enable companies to target the orebody and characterise the rock mass more accurately to increase efficiency at the processing plant.”

Rob Hough, the Science Director for CSIRO Mineral Resources, says Minerals 4D is about adding a time series to three-dimensional (3D) data. Essentially, it’s about tracking mineralogy over time.

The mining industry is now capable, through its geophysical sensing technology, to create extremely accurate 3D spatial models of orebodies, but 4D adds in the critical time element – tracking that mineralogy through the metal production line as if it were a barcode in a manufacturing circuit.

The concept involves linking modular mining operations to sensors – including fibre optics and systems attached to robots – to precisely characterise material in the subsurface before mining, through to a mine face, bench, conveyor, stockpile, truck, train or a ship.

Then you can measure the chemistry, mineralogy and rock structures at a range of scales, and provide unprecedented detail and volumes of data that capture ore and waste variability. Measuring the mineralogy is critical to understanding the quality, so where the value is created and lost.

This is like the artificial intelligence algorithms that companies such as Petra Data Science are developing to track ore from the pit to the processing plant.

A focus on value, rather than volume, means less waste and emissions in this context.

“If you have the knowledge of what you’re dealing with in a 3D picture you can then start to make predictions as to how minerals will perform when you go to mine, through to process and beneficiation,” Hough says.

“Operators can choose one set of mining or processing systems over another, knowing the texture and hardness of a material. We need to understand what is in the rock mass in terms of the minerals, but also how hard it is, its strength and how it breaks up to best separate the ore from the waste rock.”

Drone-deployed sensors

It is now possible to produce a detailed face map of a mine, fly a drone with spectral sensors to image surface mineralogy and use data analytics to identify correlations between ore types and rock strength. X-ray diffraction is also being used for analysis. These instruments are applied to samples in the field, drill holes and at bespoke laboratories that run thousands of samples at a low cost in order to build a 3D mineralogy model.

“We have a range of sensors available, but we don’t yet have a fully ‘sensed’ mine,” Hough adds.

“What we’re missing is all sensors in place, in a given operation. We’re also missing the assembling of data to inform decision making throughout the process as it happens – we need that information conveyed in real time and viewed in our remote operations centres.”

Advanced sensor-based ore-sorting

CSIRO partnered with RFC Ambrian and Advisian Digital to launch joint venture, NextOre, to deliver a sensor that intelligently directs a conveyor – sorting valuable ore from waste. CSIRO said NextOre has three trials of the sensor system underway at mine sites, with up to three more systems to be delivered this year.

“On the back of better data, we should be able to take advantage of applied mathematics that will then allow us to move to artificial intelligence and machine learning,” Hough says. “I can see a real-time conveyor belt start making automatic decisions about what is coming down the line. It’s the ultimate sensing and sorting solution.”

Reducing energy and water use

Sellers believes a move to precision mining can improve the conditions for communities living nearby mines, and even improve the social acceptance of mining.

He said several companies are testing out the value cases of sensors and data integration, and he understands they need to see proof that precision mining works on the ground. The economic benefits of sensing were demonstrated recently at a Western Australia iron ore mine, where A$25 million ($17 million) of additional resources were discovered using data provided by a relatively inexpensive hyperspectral sensor, according to CSIRO.

A Chilean copper mine is testing up to 10 types of sensors, complementing other recent trials in Australia and CSIRO desktop studies, it said. Another study found a mining company could make the same profit as it is now, but with a 30% reduction in capital and operating costs.

“Once miners gain confidence that we can actually do this, I think it will take off very quickly,” he says.

Precision mineral exploration and discovery

Beyond the mine itself, tracking minerals over time – in 4D – will also benefit greenfields exploration upstream.

According to CSIRO Digital Expert, Ryan Fraser, implementing the Minerals 4D concept is at its most challenging at the exploration and discovery stage – the point where data are sparse, and little is known about a potential target orebody.

“For example, we know a lot about a deposit such as Mount Isa, including how it forms. So, can we use the intelligence we have of that mineral system to foresee where the next Mount Isa will be?” he asks.

Fraser says if we understand how mineralogy evolves over time and the overall geological process, we can then look for signatures across the Australian landscape that help to identify similar things.

“Normally you drill in these spots, take back samples, check data and then in about two years you might have some idea of what’s under the surface and have some idea of mineral boundaries.”

The new sampling techniques will be far quicker and more efficient, he says.

“Instead of sampling a sparse, evenly spaced grid, we use machine learning to reduce uncertainties and guide where to sample and that will enable us to do much smarter edge detection of mineral boundaries,” Fraser explains.

Already this kind of predictive work has been tested in a project for the South Australian (SA) government at Coompana in SA with surprisingly accurate results and significant cost savings over traditional methods, according to CSIRO.

Other key challenges that researchers and the industry are working to address to make this a reality, include designing and developing sensors robust enough to work effectively in the mining environment (for example, in robotic cutting machines) and across rock types, and understanding which sites in the mine process are most suitable for sensors.

CSIRO concluded: “These sensors will be linked to precise and automated drilling, cutting and blasting technologies under development through Mining3 to transform the way that mining is performed.”

Novo looks to scrap metal industry for Egina gold nugget separation options

Novo Resources says it has completed encouraging processing trials on gravels extracted from its joint venture Egina gold project, in the Pilbara of Western Australia, at Steinert’s testing facility in Cologne, Germany.

Phase one of the company’s joint venture with Sumitomo Corp at the Egina gold project centres around gaining a better understanding of geology (grade, continuity, controls, gold particle size distribution, gold location within gravels, gold genesis, etc.) but also involves high level desktop studies and trials to develop potential future processing and mining methodologies.

Preliminary tests of eddy current separator (ECS) technology indicate promising potential to directly extract gold nuggets from gravel, the company said. This is one of several dry processing methodologies being considered by Novo for gold recovery at the project.

Tests conducted on a spectrum of nugget sizes ranging from 1-10 mm demonstrated consistently high gold nugget recovery via ECS technology. Nuggets that underwent testing were recently extracted from gravels at Egina, the company said.

ECSs are predominantly used to recover select metals in the scrap metal industry. Material is fed onto a conveyor, the head pulley of which contains an adjustable high-powered magnet spinning at very high rotation rates, 4,000 rpm in Novo’s tests, independent of the speed of the conveyor, Novo said. This spinning magnet induces an alternating magnetic field that differentially repels non-magnetic metals such as gold.

This magnetic repulsion causes gold nuggets to lift, or fling, off the end of the conveyor belt where they can be separated from waste material by a steel plate. These trials were designed to establish whether Egina gold nuggets react sufficiently to reliably be separated from waste material.

Novo said: “Gold at Egina predominantly occurs as free nuggets of which most are above 1 mm in size. This presents opportunity to explore innovative technologies, some used commercially in other applications such as ECS technology, to assess their efficacy for use at the Egina gold project.”

In addition to ECS technology, Novo conducted initial testing of Steinert mechanical sorting technology to detect small gold nuggets utilising an Argos EM electro-magnetic sensor, it said. Fine gold nuggets, around 1 mm, were consistently and readily detected indicating potential for direct mechanical sorting of gold nuggets, Novo said.

As a result, a combination of mechanical sorting and ECS technology is also being considered as a potentially viable means of dry processing at Egina, the company said.

Rob Humphryson, CEO and Director of Novo, said: “We are very encouraged by these initial laboratory test results utilising ECS technology. Our mantra when testing new technology and its application to our projects is to ‘test quickly and test cheaply’, and we now have in hand sufficient encouragement from these tests to consider ECS technology highly prospective for application in the field.”

The company said this preliminary testing shows ECS technology can play an important role at Egina, with potential application as a processing solution or an exploration tool, or both. “This technology generates significant inherent advantages: it requires no water, no chemicals, is of low capital cost and is readily mobile. It can also be employed along with other technologies and is scalable,” the company said.

Novo thinks field tests are warranted at larger scale to better understand recovery efficiencies, operating costs and throughput rates and the Company plans further work with Steinert to study schemes in which ECS machines, or ECS machines in combination with mechanical sorting technology, can achieve efficient recovery of gold nuggets at Egina.

The company concluded: “As Novo learns more about gold size particle and mass distribution of gold in Egina gravels, the company can then begin to estimate gold recovery.”

Vista Gold Mt Todd PFS points towards use of ore sorting, fine grinding

Following extensive metallurgic test work carried out over the past year, Vista Gold looks like it has settled on a flowsheet for its Mt Todd gold project in the Northern Territory of Australia that includes ore sorting and the selection of the FLSmidth VXP mill as the preferred fine-grinding mill.

The company detailed this in an updated prefeasibility study (PFS) for the project, which factored in the results of metallurgical optimisation test work, a redesign of the fine grinding circuit, construction and ramp-up schedule changes and a comprehensive review of all aspects of the project.

The process improvements resulted in improved projected gold recovery and increased estimated gold production at Mt Todd, Vista Gold said.

According to the PFS, a 50,000 t/d operation at Mt Todd could see the operation produce 413,400 oz/y of gold over the 13-year mine life at average all-in sustaining costs of $746/oz.

The estimated initial capital requirement came in at $826 million, with the project offering an after-tax net present value (5% discount) of $823 million at a $1,350/oz gold price and a $0.70=A$1.00 exchange rate.

In the company’s metallurgy, processing and infrastructure section, it detailed the processing side of Mt Todd, saying that recent metallurgic test programs had confirmed the efficiency of ore sorting across a broad range of head grades and the natural concentration of gold in the screen undersize material prior to sorting. The company carried out such test work at TOMRA Sorting Solutions in Germany, where two-stage (X-ray Transmission and laser) sorting tests were completed using production-sized and commercially available equipment.

It also said such test work had confirmed the efficiency of fine grinding and improved gold leach recoveries at an 80% passing grind size of 40 microns, in addition to the selection of the FLSmidth VXP mill as the preferred fine-grinding mill.

The company previously sent samples to Core Metallurgy Pty to obtain fine grinding data simulating grinding in the horizontal IsaMill and to the FLSmidth Minerals Testing and Research Center to obtain data simulating grinding in the vertical VXP Mill.