Tag Archives: grade engineering

CRC ORE simplifies complexity for value

“There are a lot more variables to bulk ore sorting than just the technology,” Jon Rutter says.

The Principal Geologist of the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE), Rutter knows his stuff. He has worked underground in both narrow-vein and mass-mining operations, as well as at large scale open-pit mines; in the base and precious metal arena.

During a presentation at International Mining Events’ IPCC Virtual event in early-February, he shared a slice of this knowledge while reviewing a recent installation project CRC ORE had been involved in at a platinum group element (PGE) operation.

“The intrinsic value of bulk ore sorting comes from the delivered heterogeneity,” Rutter said. “We have got to be able to sense and divert a higher-value pod of material versus an adjacent pod of lower-grade material on a conveyor.

“You essentially want to put more material into the mill that adds value – and not what destroys value.”

Looking at the wider bulk sorting opportunity in mining, Rutter explained the sensor diversion units (SDU) in bulk ore sorting were smaller than what the mine itself can typically offer in the form of a selective mining unit (SMU), which may be comprised of a dig block totalling around 15,000 t.

A truck offers a 100-300 t opportunity, while a shovel typically comes with a 50-100 t opportunity.

Even with a modest conveyor running at a 2,000 t/h rate, an on-board sensor (eg PGNAA or PFTNA) running at a 30 second integration time (the time to analyse one grade) would provide an SDU of 16.7 t. A sensor with lower integration time (eg XRF at 10 seconds) comes in at 5.6 t.

The ability to provide analysis down to this level has enticed several major companies into testing bulk ore sorting solutions.

Anglo American has trialled bulk ore sorting solutions at copper and platinum group metal mines, while BHP recently engaged CRC ORE to examine deployment of cutting-edge preconcentration techniques under its Grade Engineering® platform at the Olympic Dam mine, in South Australia.

The SDU with bulk sorting may be that much smaller than the SMU of a typical mine plan, but lab-level precision is not required for these solutions to work, according to Rutter.

“What I need is the ability to measure the metal content adequately,” he said. “When I say adequate, this incorporates the entire error bar of the system. That system includes the inherent geology, the mineralisation style and heterogeneity. We also need to consider the precision, accuracy and integration time – which is the technology constraint; but we also need to include the weightometers, the flop gates, the diversion gates, as well as that entire mining and materials handling process right from the start – from blasting, loading, hauling and dumping to the plant.

“But for bulk ore sorting what I end up requiring from this combined data is usually a binary decision: am I above or below a certain threshold?”

He expands on the bulk ore sorting (BOS) assessment process: “The other way of looking at this is simply considering it as planned ore loss and dilution. If we go back into that dig block, in that 15,000 t of material, I’ve already incorporated planned ore loss and dilution decisions or parameters into that SMU decision. So, if we look at bulk ore sorting, I am just talking about those different attributes – the error bars of a BOS system – as the inputs or parameters for BOS planned ore loss and dilution – it’s now just at a smaller and more precise opportunity.”

The company took a two-phase approach to the BOS opportunity at the PGE operation in question.

The first phase involved carrying out heterogeneity analysis of the orebody; correlation analysis of PGEs to base metals; selection of sensor technologies (XRF and PGNAA were selected in this case), design, layout and equipment selection for the bulk ore sorting plant; natural deportment analysis of the orebody; development of a preliminary business case; the ore type selection and sampling strategy; and project planning and management.

CRC ORE and the company in question settled on a solution where a Caterpillar 992 wheel loader dropped material off to a system using a combination of grizzly, feeder, sizer, conveyors, diverter, stackers and associated equipment from MMD, used in conjunction with an ore sensing system equipped with both PGNAA and XRF sensors to continuously measure the elemental composition. The PGNAA sensor provided a “penetrative” analysis calculation whereas XRF provided a “surface” sensing calculation, Rutter explained.

An incline conveyor ahead of the diverter gate and the accept/reject stream provided the 30 second integration time the PGNAA analyser required.

Phase two of the project involved online and offline (pre-install) work; sensor calibration; proving the technology; and proving the technology can drive physical separation.

Rutter said the completion of static calibration of the sensors saw the PGNAA sensor 20-30% calibrated, and the XRF sensor 70-80% calibrated.

This outcome harked back to Rutter’s assertion that “bulk ore sorting implementation is not a plug and play opportunity”.

A dynamic calibration in online mode completed under normal conditions was required to get the PGNAA sensor up to speed. This process, meanwhile, solidified the operation of the XRF sensor.

While the two sensors were calibrated in different ways, Rutter showed data that confirmed both were in unison when it came to reading the ore/waste that came through the conveyor (see right-hand graph below).

“The two sensors are independent of each other and fundamentally very different, but they can work well together, or separately,” he said.

CRC ORE was able to prove the technology by running the same sample through the circuit a number of times, as Rutter explained: “We fed 15-20 t of run of mine material into the hopper and repeated the process 15 times, putting the same 15-20 t sample through the system. We could then start to determine the precision and accuracy of the sensors and the system.”

For further verification, the sample was crushed, sub sampled and assayed.

“We wanted a binary response to ore and waste to build confidence,” Rutter added.

Phase three involved the ramp up to production scale, going from, say, 500 t/h to 1,000 t/h; carrying out validation by campaign; and finally integrating with the operation.

There were several lessons all mining companies – and bulk sorting vendors – should keep in mind from such a project, Rutter said.

Operations need to assess the impact of mixing across the entire materials and mining handling process as soon as possible, for one.

“The earlier we can put this data into the system, the better,” Rutter said. “Without a heterogeneity signature, we cannot implement bulk ore sorting.”

He also stressed the importance of timely feedback. Sensor calibration, a secondary crushing/sampling plant and assaying were all required to build confidence in the solution.

Rutter added: “The proper calibration of sensors does require a considerable and ongoing effort…but that is no different from any other process plant or equipment.”

Operators also need to be wary of where they set these solutions up in mines, recognising this heterogeneity dynamic.

“Bulk ore sorting is quite unlikely to be universally suited to the entire deposit,” Rutter said. “The analogue for this is a flotation plant; there are ore types in the mine where you achieve better performance in the flotation plant and others where you get worse performance.”

Hatch to commercialise CRC ORE’s Grade Engineering services

CRC ORE says it has taken an exciting step forward with Hatch, signing a deal that allows the multidisciplinary management, engineering and development consultancy to commercialise its Grade Engineering® Consulting Services.

Developed by the Brisbane-based Cooperative Research Centre for Optimising Resource Extraction (CRC ORE), Grade Engineering enables miners to reduce their energy, water and waste signatures while enhancing the productivity and profitability of their operations, according to CRC ORE.

It is an integrated approach to coarse rejection that matches a suite of 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.

Grade Engineering makes it possible to more efficiently treat lower grade ores and waste to extract valuable minerals, significantly increasing the life of mines and reducing their environmental footprint.

Achievable outcomes for mines, when deploying Grade Engineering at production scale, include significantly improved return on investment and lower capital intensity, according to CRC ORE.

BHP recently engaged CRC ORE and the Grade Engineering solution at its Olympic Dam mine, in South Australia, a location where the mine is actively examining bulk ore sensing and sorting opportunities.

“As Hatch adopts Grade Engineering and extends its reach into the mining industry, the value of such outcomes will increase for operations, clients and communities globally,” it added.

CRC ORE Chief Executive Officer, Dr Ben Adair (pictured signing the agreement on the left), said: “Hatch is a valued a long-term participant in CRC ORE and has actively championed Grade Engineering and its benefits to the industry. As a CRC ORE innovation, we are pleased that Grade Engineering will continue to be delivered by such a capable and engaged team.”

Dr Adair added: “At CRC ORE, our goal has been to develop our solutions to the highest possible standard and then ensure these are then managed by the most capable practitioners to take them to industry. Hatch is the perfect partner to ensure the long-term future of Grade Engineering.”

Under the terms of the commercialisation arrangement, Hatch will use Grade Engineering Intellectual Property for its consulting services.

Hatch Managing Director Australia and Asia, Jan Kwak (pictured signing the agreement on the right), said it was an honour to provide Grade Engineering consulting services.

“Being able to offer Grade Engineering as service is an exciting and positive step forward for Hatch and the mining industry,” Kwak said. “Grade Engineering enables miners to reduce their energy, water and waste signatures while enhancing the productivity and profitability of their operations.

“It also brings us a step closer to our vision for process intensification.”

The Grade Engineering team at Hatch will be headed by Dr Sevda Dehkhoda who has been working closely with CRC ORE since 2019.

“We look forward to continuing the legacy of CRC ORE by enabling the mining industry to intensify operational performance and minimise environmental footprint of the process by refining less waste,” Dr Dehkhoda said. “Adopting Grade Engineering into Hatch’s end-to-end value chain optimisation service offering strengthens Hatch’s position and its commitment to making positive change for mining operations and their communities.”

To facilitate the transition, CRC ORE’s Grade Engineering team will relocate to Hatch’s Brisbane office, supporting Hatch with current and potential users of Grade Engineering.

BHP engages CRC ORE for Olympic Dam bulk ore sorting study

BHP has engaged the services of Australia-based research consortium, the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE), to examine deployment of cutting-edge preconcentration techniques.

Olympic Dam, 560 km north of Adelaide, is one of the world’s most significant deposits of copper, gold, silver, and uranium. This large BHP site is made up of underground and surface operations and conducts fully integrated processing from ore to metal.

The South Australia operation is one of the locations where BHP is actively examining bulk ore sensing and sorting opportunities – techniques within the CRC ORE Grade Engineering® suite of preconcentration technologies.

Grade Engineering is an integrated approach to coarse rejection that matches a suite of 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.

CRC ORE was requested by BHP to assist in the assessment of bulk ore sorting opportunities at Olympic Dam, it said.

BHP Principal Technology, Lee Bolden, said that as a CRC ORE participant, the diversified miner had watched with interest the sorting and sensing work that CRC ORE is undertaking in open-pit and underground operations.

“It made sense for us to have CRC ORE provide us with valuable insights on this work and input into our bulk ore sorting plans,” Bolden said.

BHP received a high-level bulk ore sorting deployment strategy from CRC ORE for Olympic Dam, along with a framework and calculator for the quantification and ranking of bulk ore sorting strategies at the operation.

CRC ORE also identified the critical work and data required to strengthen the evaluation of bulk ore sorting with the Olympic Dam Project team.

CRC ORE Chief Operating Officer, Dr Luke Keeney, said there were several deployment options among the opportunities assessed.

“We explored sublevel open stoping under the current mining environment, along with block caving as part of future-state mining options,” Dr Keeney said.

As part of the assessment, BHP received a high-level estimate of value from these deployment options.

Dr Keeney said the engagement of CRC ORE at Olympic Dam demonstrated the commitment of big miners to apply innovation to their processes.

“With the need for valuable minerals continuing to grow and mining these minerals becoming ever more difficult, mine operators need to think differently,” Dr Keeney said.

“Bulk ore sorting, and other Grade Engineering opportunities become increasingly competitive and complementary solutions where mined grades decline and mining dilution increases.”

Kalgoorlie-Boulder Mining Innovation Hub uncovers a fraction of processing value

Extensive testing conducted by a Kalgoorlie, Western Australia-based research hub has found Western Australian Goldfields mine sites can add value to their operations by focusing on small size fractions.

In recent decades, the primary driver to maximise profitability of mining operations has been to mine and process as much material as possible to exploit economies of scale. This has led to bigger equipment, higher throughput and greater production, but not necessarily efficient use of resources.

With the concerns of declining grades, more complex orebodies, greater haulage distances, higher energy costs and water usage, any approach that can alleviate the impact of these issues is highly desirable.

The Kalgoorlie-Boulder Mining Innovation Hub recently explored use of a pre-concentration technique known as “Grade by Size Deportment”.

“This technique exploits the propensity for some ores to exhibit preferential breakage leading to concentration of minerals in specific size fractions,” it explained.

Several sites within the Goldfields region of WA showed significant potential for separation by size to provide value to their operations, according to the hub. This is particularly the case where either marginal grades are present or growing distances from face to surface, or, from mine to mill, are subject to increasing transport costs, it said.

Research and test work by the hub show that natural grade by size deportment during coarse rock breakage and screening is a key lever for generating high-value coarse separation, it said. This, in turn, can drive better productivity and returns for mine operators.

The Kal Hub, established in 2018 by the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE), enables focused collaboration between researchers; mining equipment, technology and services suppliers; and mining companies to unlock value for Australian mining through technology development.

CRC ORE Chief Operating Officer, Dr Luke Keeney, said: “In a short amount of time, the hub has been able to bring together some of the most innovative people in industry and research, enabling collaborative innovation to occur.

“This collaboration is good for the Goldfields, and for the wider mining industry, as it demonstrates the benefits mine sites can experience by deploying various aspects of Grade Engineering®, including grade-by-size deportment.”

Grade Engineering is a system-based methodology developed by CRC ORE designed to reject low value material early in the extraction value chain and pre-concentrate processing plant feed. A key lever for successful Grade Engineering is grade-by-size deportment, the hub said.

The Kal Hub Technical Advisor, Dr Laurence Dyer, said the objective of the Grade-by-Size Deportment project was to undertake initial representative sample testing to determine natural deportment Response Rankings at a range of deposits in the Kalgoorlie-Boulder region.

“This project provided an introduction for industry participants to Grade Engineering and an indication of potential opportunities that grade-by-size deportment may present,” Dr Dyer said.

“A number of companies came on board and we were able to obtain diamond drill core and reverse circulation (RC) drilling samples from a variety of sites in the Goldfields to crush, screen and assay to develop a snapshot of responses to this approach.”

Samples were crushed where necessary and screened into up to six size fractions, with a finer set of screens used for the RC samples to accommodate the difference in particle size distribution.

As expected, gold sites displayed significant variation in response, while all nickel sites tested showed significant upgrade in the finer fractions of both nickel and cobalt, the hub said.

“RC samples were a compelling sample option due to their prevalence and self-preparation for screening, however there remains a question as to the legitimacy of the results they generate,” it added.

Dr Dyer said: “Gold samples produced varied data with the majority of sites producing low to moderate upgrades on average.

“The RC samples generated greater variation and often decreased in grade at the finest size fractions, likely due to particles being below liberation size, creating issues with the response ranking fit.”

The Kal Hub research also showed nickel produced far more consistent behaviour with all sites producing moderate to high responses for both nickel and cobalt. While for some samples the nickel and cobalt response rankings matched well, in others, the nickel upgraded significantly better, it said.

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

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.

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.

CRC ORE grade engineering trial pays off for Minera San Cristóbal

A successful full-scale production trial of Australia-developed grade engineering techniques is paying dividends for a South American mine, and its local workers, according to CRC ORE.

Once fully implemented, this is expected to generate an additional A$451 million ($312 million) in profit for the mine and reduce its energy consumption, it said.

Located in the south-western Bolivian province of Nor Lípez, and owned by Sumitomo, Minera San Cristóbal (MSC) is the country’s largest mine. Operating since 2007, the mine produces around 1,500 t/d of zinc-silver and lead-silver concentrates. To achieve this result, MSC needs to move a daily average of 150,000 t of rock – ore and waste.

Part of MSC’s vision is to “develop a model mining operation through safe operations, at low cost, with innovative technology”.

Through its wholly-owned subsidiary, Summit Mining International, Sumitomo is a participant of the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE). Based in Brisbane, Australia, CRC ORE works to minimise the impact of declining grades and radically improve the productivity, energy and water signatures of mining operations, CRC ORE said.

The centre is jointly funded by what it calls ‘Essential Participants’, which includes mining companies such as Sumitomo; mining equipment, technology and services (METS) companies; research organisations; and the Australia Government.

One of CRC ORE’s key solutions developed for the mining industry is grade engineering. “This solution deploys a range of waste rejection technologies that integrate with a suite of separation technologies relevant to ore specific characteristics,” CRC ORE said. “A deeper understanding of the orebody can be achieved, leading to the ability to exploit inherent ore deposit heterogeneity and variability.”

For mining operations such as MSC, this involves an innovative approach to the early separation of ore from waste material, minimising the impact of declining grades and productivity.

CRC ORE and MSC teams conducted site studies and analysis in 2017 to determine the level of opportunity available at the mine by deploying grade engineering, and a great deal of potential was evident.

Since late 2018, CRC ORE and Sumitomo have been working together on a full-scale production trial of grade engineering using screening at MSC. A Metso Lokotrack ST2.8 mobile screening plant, which can process up to 450 t/h, was deployed on site to assist in providing a production-scale testing capability.

The trial focused on upgrading mineralised waste from the pit to determine if grade engineering could efficiently produce a new economic stream of valuable material that could then be combined with run of mine feed through to the concentrator and produce a positive net smelter return.

CRC ORE Chief Executive Officer, Ben Adair, said initial results of the trial were impressive and encouraging, with 66% of value now contained in just 25% of the grade engineered mass.

“So far, results show that by applying grade engineering to areas previously designated as ‘mineralised waste’, the value of grade engineered feed to the mill can be increased by over 2.5 times,” Adair said.

“This has the potential to convert this waste material into high-grade ore feed with associated opportunity to increase metal production and reduce process power and water intensities.”

A 15-20% reduction in energy has been evident in the mine’s SAG mill when processing a combined grade engineered and direct run-of-mine feed, according to CRC ORE.

The success of the grade engineering trial has led to Sumitomo considering deployment of grade engineering techniques for life of mine extensions, CRC ORE said.

MSC Operations Director, Dave King, said: “The big benefit of grade engineering is its potential ability to extend the life of the mine and add over A$451 million in profit to its value.”

To fulfil its goals of knowledge transfer and for its technology to directly benefit the local mining industry, CRC ORE says it has recently commenced similar production trials at Australia mining operations.