Tag Archives: nickel

Pit N Portal receives Notice to Proceed at Mincor’s Kambalda Nickel Operations

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With funding now materially advanced and board approval in place, Mincor says it has issued a “Notice to Proceed” to its underground mining contractor, Pit N Portal, to start work at the Kambalda Nickel Operations in Western Australia.

In line with the binding contract executed in May 2020, Pit N Portal has 60 days to plan and mobilise for commencement of the contract.

The announcement of a final investment decision for the planned re-commencement of nickel mining at Kambalda by Mincor is supported by a credit approved term sheet agreed with two Tier-1 international banks to provide a secured A$55 million ($40 million) project finance facility. The facility, together with the company’s existing cash reserves of more than A$100 million, will allow Mincor to efficiently execute the delivery of its nickel restart plan in line with the definitive feasibility study (DFS) announced in March 2020, it said.

The contract with Pit N Portal encompasses a five-year pact for the new Cassini nickel mine, where early surface works were recently completed, and a three-year contract (plus one two-year option) at the Northern Operations (the brownfields Durkin North and Long nickel mines – both of which are on care and maintenance having previously operated). These two assets (Cassini and Northern Operations) make up the planned nickel operation.

Mincor says there are already several Pit N Portal personnel on-site following the commencement of an early works program.

“With all required key environmental and State Government permitting in place to commence, Mincor anticipates that mobilisation will ramp-up quickly over the coming weeks, with commercial mine development and surface construction expected to be in full swing during the December 2020 quarter,” the company said.

Subject to unforeseen delays, Mincor is targeting commencement of ore production early in the December 2021 quarter. First ore delivery to the BHP Nickel West Kambalda nickel concentrator and first nickel concentrate production is expected in the March 2022 quarter.

The “Mincor Nickel Operations” DFS from earlier this year confirmed the potential to develop a five‐year operation forecast to produce 71,000 t of nickel and 5,000 t of copper on a life-of-mine basis, with peak annual nickel-in-concentrate production of more than 16,000 t/y at a forecast life of mine unit cost of $2.35/lb.

Atlantic Nickel ready to delve underground for Santa Rita mine life expansion

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Atlantic Nickel has released a preliminary economic assessment (PEA) on its Santa Rita nickel mine, in Brazil, that shows the potential for the company to become one of the largest sustainable nickel sulphide producers in the world.

The announcement, made in concert with Appian Capital Advisory LLP (the owner of Atlantic Nickel), follows the recommencement of open-pit mining at Santa Rita in August 2019.

This new NI 43-101 technical report outlines a 34-year mine life for Santa Rita, in Bahia, with eight years of open-pit production, underpinned by proven and probable reserves of 50.6 Mt at 0.31% NiS, and 26 years of underground mining.

The open-pit mine plan was prepared to prefeasibility study level and encompasses a large open pit and a nearby, much smaller satellite open pit along strike. Both pits will be mined with conventional mining equipment, and the plan will be executed in 10 phases, the company says.

The open pit is scheduled over a period of eight years, ending in 2028, with operations using standard methods of drilling and blasting, loading, and hauling. It would produce 20,000-25,000 t/y of contained nickel equivalent at a C1 cost of $2.97/lb Ni and an all-in sustaining cost (AISC) of $4.12/lb Ni, the company says.

The Santa Rita process plant, having started production in 2009, was completely refurbished and recommissioned in the second half of 2019 in line with the mine restart. The plant consists of crushing, grinding, flotation, thickening and filtration unit operations to produce a saleable nickel concentrate. Flotation tailings are pumped to a tailings storage facility, while grinding is performed by a SAG mill, two ball mills and two pebble crushers. This is followed by a conditioning circuit and a flotation circuit, with the final concentrate thickened and pumped to storage tanks ready for filtration. Concentrate is filtered in a Larox (Metso Outotec) pressure filter. Following filtration, the final concentrate is trucked to the port of Ilhéus where it is loaded onto ships for transport to market.

The mineral resource estimate for the expansion case consists of 94.2 Mt of measured and indicated resources across open-pit and underground mining at average grades of 0.41% NiS, 0.14% Cu, 0.01% Co, 0.03 g/t Pd, 0.07 g/t Pt and 0.05 g/t Au, with 90.6 Mt of inferred resource at 0.54% NiS, 0.17% Cu, 0.02% Co, 0.04 g/t Pd, 0.09 g/t Pt and 0.06 g/t Au.

Sublevel Caving (SLC) was selected as the mining method for the underground portion of the deposit based on the amenable geometry of the deposit, and because productivity and cost advantages of SLC enable greater exploitation of the underground resource at greater margin than more selective mining methods, Atlantic Nickel said.

“The geometry of the deposit and the location below a mined open pit are similar to the Ernest Henry SLC, which is successfully operated by Ernest Henry Mining (a subsidiary of Glencore) in Queensland, Australia,” the company added.

The SLC mining method employs long-hole drilling and blasting techniques to extract mineralisation sequentially from the surface to the bottom of the deposit. The method does not require backfill and, therefore, relies on the overlying waste rock to cave and fill the mined void, the company explained. Caving of the overlying waste rock results in surface subsidence above and in the immediate vicinity of the underground deposit, but the subsidence will not interfere with open-pit mining since initial production from underground is planned to commence in 2028 when open-pit mining is completed.

Infrastructure capital and development of the underground project is planned to start at the beginning of 2026, with production from the underground ramping-up over a seven-year period until full production of 6.2 Mt/y is achieved.

The underground portion of the resource considered in the PEA plan consists of 43.5 Mt of indicated resources and 90.6 Mt of inferred resources. This resource was used to come up with a 40,000-45,000 t/y of contained nickel equivalent production profile for the underground operation over life of mine at a C1 cost of $2.17/lb Ni and an AISC of $3.92/lb Ni.

The SLC mining layout in the PEA comprises 37 mining levels spaced at vertical intervals of 25 m. Each level is made up of parallel and evenly spaced drill drives from which production drilling and blasting occur. Once blasted, the mineralisation is loaded from the drill drives using LHDs and loaded into trucks for haulage to the surface during the initial ramp-up phase, and later to ore passes feeding an underground crushing station and conveying to surface via an inclined tunnel.

“The SLC method employs a top-down mining sequence that enables production to ramp-up quickly once the top of the underground deposit has been accessed,” Atlantic Nickel says. “The method also enables high production rates as the mining cycle is simplified by the standardisation of development and production and with no backfilling required.”

While still early days in terms of the underground mine’s development plans, the company assumed the use of automated LHDs, longhole drilling and jumbo development drilling in the PEA, a spokesperson for Atlantic Nickel confirmed to IM. This saw Epiroc and Sandvik provide price inputs, with design layouts anticipating such equipment.

“Subsequent studies will optimise the equipment and layouts integration,” the spokesperson added.

And, while the current study assumes the use of a diesel-powered fleet, battery-electric vehicles will also provide upside in future studies and further reduce energy costs, equipment maintenance costs and ventilation power costs, the spokesperson said.

“Both tethered and battery will be look at for specific applications within the mine such as loading from drawpoints and feeding the underground crusher from the bottom of ore passes,” the spokesperson said.

The flotation test work gave similar results to those obtained with open-pit material; hence, plant performance is not expected to be significantly different for underground material, the company said. Underground feed will be treated in Atlantic Nickel’s existing process plant with only minor modifications required, likely to the grinding circuit.

New surface infrastructure associated with the underground mine would include the following:

  • A box cut and portal located to the west of the north end of the open pit;
  • A conveyor portal connecting to the bottom of the existing crusher installation;
  • A temporary construction portal in the west wall at the north end of the open pit on the 82 m RL bench;
  • Multiple ventilation raise surface collars on the western side of the open pit;
  • Ventilation adits on the west wall at the south end of the open pit on the 10 m RL bench;
  • Dewatering pond for storing, settling and recycling water from underground;
  • Electrical reticulation to the portals, adits and services; and
  • Shotcrete batch plant.

After completion of open pit mining, a new tailings storage facility would be required to store the additional 134 Mt of tailings to be produced from the underground mine over a period of 28 years. Like the existing tailings storage facility, raises will be constructed using a downstream method, the company said.

Total capital associated with the underground expansion amounts to $1.3 billion over the 34-year combined operation, with only $355 million of that being spent during the first five years of underground development commencing in 2026. The expansion is partially self-funding with cash flows generated from the open-pit mining operation, the company said.

Base metal price rise sparks nickel-cobalt laterite activity

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With the nickel price having recovered from the late March lows and now trading above the $15,000/t mark on the LME, those miners and developers tied to the base metal have been making moves in the last few months. Alan Taylor at ALTA 2020 Online recently highlighted some of the more significant news in the nickel-cobalt laterite sector.

It comes just two months prior to the start of the virtual conference.

Ravensthorpe restarts

Often viewed as an industry bellwether, the First Quantum-owned Ravensthorpe nickel mine (pictured) in Western Australia is continuing with a restart plan despite coronavirus challenges, the company recently reported.

The acid plant and atmospheric leaching operations restarted in March 2020, with the first high pressure acid leach (HPAL) circuit brought on stream in mid-April, followed by product drying and containerising of nickel mixed hydroxide product.

The second HPAL circuit is scheduled to come online in due course.

Director of Exploration, Mike Christie, said previously at Paydirt’s Africa Downunder conference in September 2019 that the mine plans to ramp-up production to between 20,000-30,000 t/y of nickel over the next few years.

Some 1,979 t of nickel was produced at the operation in the June quarter.

Ramu expansion engineering ready

Looking back to an ASX announcement on October 8, 2018, from Highland Pacific, a minority partner in the Ramu Nickel JV, a A$1.5 billion ($1.1 billion) expansion continues to be investigated.

Ramu is currently rated at 34,000 t/y nickel and 3,300 t/y cobalt as mixed hydroxide precipitate (MHP), achieved in 2017.

By way of an update, Craig Lennon, Executive Director of Highlands Pacific (now a wholly-owned subsidiary of Conic Metals Corp), advised Taylor that the expansion project is engineering-ready, although the final decision to proceed is dependent on factors including global markets and final permitting decisions in Papua New Guinea.

Indonesia projects slowed

There are several HPAL projects in Indonesia aimed at producing MHP for the electric vehicle battery industry. They received environmental approvals in January 2020, allowing them to proceed with construction, according to Jack Anderson of Roskill, however, their development depends on Chinese expertise and progress is likely to be slowed due to Chinese workers involved in the construction being quarantined.

Sunrise PEP progressing towards Q3 2020 completion

Fluor Australia Pty, as Project Management Contractor, is working with the Clean TeQ-owned Sunrise nickel/cobalt/scandium project team to develop a comprehensive Project Execution Plan (PEP) for the Sunrise project in New South Wales, Australia, according to reports.

The company expects that completion and announcement of the outcomes will be late in the September quarter.

Clean TeQ advises that the PEP capital estimate will likely be higher than the 2018 definitive feasibility study figure, while the operating costs indicate the project will remain extremely competitive because of strong cobalt by-product credits.

Queensland offers funding for Sconi

The Queensland government has offered Australian Mines a conditional financial support package for the development of the Sconi cobalt-nickel-scandium project in north Queensland, the mine developer says.

The package will be subject to a number of conditions including a timetable for securing an offtake agreement for all of the nickel sulphate and cobalt sulphate production (September 2020); delivery of a detailed execution plan, obtaining approved financing for construction and making a final investment decision; appointing an engineering, procurement, construction management contractor (end 2020); and completion of construction (July 2023).

It also includes conditions for employment of people and engagement of independent contractors working directly on the project.

Australian Mines, in August, became the first mineral resources company to be certified a “Carbon Neutral Organisation” under the Australian Government’s Climate Active program.

Piauí project granted preliminary environmental licence

Brazilian Nickel plc announced the granting of a Preliminary Environmental Licence by the Brazilian Piauí State Environmental Agency on October 22, 2019, for the mining and heap leaching processing plant to produce nickel and cobalt products for the battery industry at its Piauí nickel project.

The company says it is now ready to advance through a bankable feasibility study (BFS) enable financing and application for a construction permit.

An operating demonstration plant has leached 8,000 t of ore in full-height heaps and has achieved first sales of nickel and cobalt products. This will allow the company to expand the existing demonstration plant by a factor of 10 to 1,400 t/y nickel to jump-start the project to immediate producer status without the need for a BFS.

Process innovations

On the process innovation front, there have recently been two major stories from Pure Minerals and Metso Outotec.

Pure Minerals has secured a A$2.55 million grant via its wholly owned subsidiary Queensland Pacific Metals Pty Ltd (QPM) for the Townsville Energy Chemicals Hub (TECH) project. QPM and project partners Direct Nickel Projects Pty Ltd (DNi) and the Commonwealth Scientific and Industrial Research Organisation (CSIRO) successfully applied for the Federal Government grant.

The TECH project will process imported, high-grade nickel-cobalt laterite ore from New Caledonia to produce nickel sulphate, cobalt sulphate and other valuable co-products. If it proceeds it will be the first commercial application of the DNi Process™.

The next step is a pilot plant test work program on a bulk sample received from New Caledonia ore supply partners.

And, finally, Metso Outotec has introduced a new novel superheated steam sulphation process.

The process is a recent development of Metso Outotec, Finland, and has been successfully tested on a laboratory scale. It includes agglomeration of ground laterite with sulphuric acid, then superheated steam treatment at elevated temperature followed by water leaching. Nickel and cobalt are sulphated and solubilised. Iron dissolution is minimised by conversion from goethite to hematite. Sulphuric acid consumption is said to be moderate.

A paper on the process is to be presented by Metso Outotec in the ‘Nickel-Cobalt-Copper Conference’ at ALTA 2020 Online.

Pressure Acid Leaching for the production of nickel and cobalt for the battery industry is one of the key topics of the ‘Nickel-Cobalt-Copper Conference’ to be held on November 10-12 as part of ALTA 2020 Online.

This will be followed on November 13 by a short course ‘The ART of HPAL – The way of Success’. The course presenters played key roles as owner and engineering contractor in Sumitomo’s successful Coral Bay and Taganito HPAL projects in the Philippines.

International Mining is a media partner of ALTA 2020 Online

Barminco to take on Odysseus nickel mining gig for Western Areas

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Perenti’s hard-rock underground miner Barminco has been awarded a development and production contract at Western Areas’ Odysseus mine, in Western Australia.

The contract at Odysseus, part of the Cosmos nickel operation, is valued at around A$200 million ($146 million) over five years and follows on from the earlier rehabilitation works completed by Barminco at the mine.

Western Areas acquired Cosmos in October 2015 and commenced the redevelopment of Odysseus in January 2019. Once in production, Odysseus is expected to produce 14,000-15,000 t/y of nickel concentrate, becoming Western Areas third nickel mine in Western Australia.

Western Areas Managing Director, Dan Lougher, said today (September 8) that excellent progress had been made on the underground and surface infrastructure works at Odysseus, with minimal COVID-19 impacts.

“We have reached a critical milestone with the firing of the full-face development of the Odysseus decline, which is now heading across to the orebody,” he said. “A significant amount of preparation and support work has been delivered across the site to reach this milestone.

“We now have our eye on the delivery of the first ore tonnes mined from underground in the first quarter of financial year 2022.”

Barminco’s Chief Executive Officer, Paul Muller, said the company was excited to continue its relationship with the Western Areas team, which began in 2005 at the Forrestania mine and has now grown to include the Cosmos nickel operation.

“Odysseus is a significant project to bring on-stream, and the five-year term demonstrates the trust and confidence Western Areas has in Barminco to continuously improve and deliver for them,” he said.

MBV’s 3DPM system heads to Independence Group’s Nova nickel operation

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MBV Systems has received another order from the Australia mining sector for its 3DPM system, with the Sweden-based company set to deliver the online particle size distribution platform to Independence Group’s Nova nickel operation in Western Australia.

The order follows a trial at the nickel operation, which produced 30,436 t of nickel concentrate in the 12 months ending June 30, 2020.

The 3DPM system is used to increase knowledge and understanding of the material flow and hence improve the production efficiency and product quality at mine sites, MBV Systems says. It provides online particle size distribution measurements of rocks and bulk material through 3D measurements on conveyor belts.

“In this case (at Nova), the size distribution is used as a ‘disturbance variable’ in a model predictive controller for a SAG mill,” the company said. “The model can predict up to 100 seconds in advance the effect (of the material) on the SAG mill weight. This has greatly improved the stability of the grinding circuit as well as increased the energy efficiency of the mill.”

The rock bolt detection feature of the system detects rock bolts in real time, alerting the operator and allowing them to stop the feed to remove the rock bolt. This feature will enable IGO to act quickly and avoid unplanned downtime and costly damages, according to MBV Systems.

IGO control systems engineers are currently looking at other ways in which the measurement system can be used. One possible application is to use these measurements to track the wear of the jaw crusher liners, according to MBV.

“As the jaw crusher liners wear down, the average size of the crushed particles increases,” MBV Systems says. “This will allow IGO to do jaw crusher maintenance in a smarter way.”

The commissioning of the 3DPM system was carried out remotely due to COVID-19 restrictions, the company noted.

Lars Lindqvist, CEO at MBV Systems, said: “This is a very exciting order for us since IGO is a very interesting mining company which believes in a green energy future by delivering the metals needed for new-age batteries.”

The Nova contract follows a signed agreement with Rio Tinto from earlier this year that will see the mining company trial its 3DPM vision system at one of its mine sites in Western Australia.

Australian Mines makes history with certified carbon neutral status

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Australian Mines says it has become the first mineral resources company to be certified a “Carbon Neutral Organisation” under the Australian Government’s Climate Active program.

Climate Active is the most rigorous and credible carbon neutral certification available in Australia, according to the company, and meeting the “Climate Active Carbon Neutral Standard” means Australian Mines’ carbon neutral status is based on best practice, international standards and genuine emissions reductions.

Last month, the Queensland Government offered a conditional financial support package to Australian Mines’ 100% owned Sconi cobalt-nickel-scandium project in the north of the state. When fully developed, Sconi is forecast to be one of the most cost competitive cobalt-producing, nickel operations in the world, Australian Mines says.

The 2018 Sconi bankable feasibility study outlined a three open pit, 2 Mt/y operation that could produce some 8,496 t/y of cobalt sulphate, 53,301 t/y of nickel sulphate and 89 t/y of scandium oxide over the 18-year mine life.

“Australian Mines ability to maintain carbon neutral certification will underpin its position as a sustainable business that incorporates leading environmental, social and governance (ESG) practices,” it said. The company is already an approved member of the Initiative for Responsible Mining Assurance (IRMA), which independently verifies and certifies socially and environmentally responsible mining.

Australian Mines’ Managing Director, Benjamin Bell, said becoming the first Climate Active Carbon Neutral mineral resources company is consistent with Australian Mines’ commitment to leading on ESG.

“It follows the approval in March 2020 of our membership of IRMA and the Queensland Government recognising our commitment to the communities where we operate by granting ‘Prescribed Project’ status to our flagship Sconi project in 2019,” he said.

Australian Mines’ primary focus is to sustainably develop the Sconi project into a globally significant, ethical, reliable source of technology metals to meet the rapid growth in the electric vehicle and energy storage industries, it says.

A key part of sustainably developing Sconi is the company’s carbon neutrality plan designed to reduce greenhouse gas emissions by implementing energy saving initiatives coupled with offsetting any unavoidable emissions.

“Being certified Carbon Neutral by Climate Active is part of building a sustainable future for Australian Mines, long-term value for our shareholders and a better environment for all our stakeholders,” Bell said. “Members of the Climate Active Network are responsible for over 22 Mt of carbon emissions being offset, which is the equivalent of taking all of Sydney’s cars off the road for two years.”

MICROMINE’s Pitram solution takes control at Greece mine

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MICROMINE says it is making a strong foray into Europe’s mining sector with its Pitram fleet management and mine control solution now operating in Greece.

Already used at more than 50 mining operations across six continents, the installation at the Greece mine is Pitram’s third deployment in the Aegean region, following installations at two production projects in Turkey.

“Greece has a wealth of mineral and ore deposits including gold, silver, lead, zinc, copper, nickel and bauxite – and a history of mining that dates back to ancient times,” Pitram Product Strategy Manager, Chris Higgins, said. “Turkey also has abundant source of industrial raw materials, rare earth minerals and precious metals including gold, copper, zinc, chrome, nickel, iron, lead, mercury, tin and magnesium.

“As a result, international operators and miners are developing projects across the Aegean and Pitram is providing the data insights needed to ensure the operations are well controlled.”

More than 10 mining operations in Europe are currently using Pitram to record, manage and process mine data in real time, according to the company. The scalable solution has now been deployed at the three underground gold, copper and zinc mines in Turkey and Greece.

The Greece project is well advanced with Pitram playing a crucial role in a major refurbishment and expansion of existing operations, the company says.

“Comprising 11 modules – including materials management, OLAP analysis, shift planner and fleet management – Pitram is a sophisticated mine control and management reporting application enabling the miners to capture data, make quicker, evidence-based decisions and allocate resources more effectively,” MICROMINE says.

As production ramped up at the Greece underground mine, the operators chose Pitram, according to MICROMINE, because they needed a solution that would enable them to:

  • Improve development and production mining cycles;
  • Accurately track materials from source to processing;
  • Provide OLAP reporting and analysis;
  • Enhance reactions to, and minimise the impact of, unplanned events; and
  • Increase equipment availability and utilisation.

The implementation of Pitram voice and materials management modules ensured these objectives were met by adapting the solution to meet the specific needs of the site, the company said.

Higgins added: “At MICROMINE we committed to working with our mining clients to deliver the tailored software solutions they need to meet local requirements.

“This includes providing our solutions in the languages needed – that’s why Pitram has been translated into Turkish and Greek. So, with the functionality to switch between English and the local language, all staff on-site can use the application.”

Ivanhoe advances Platreef development studies after Moolmans completes sinking

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Ivanhoe Mines has announced another milestone at the Platreef platinum group metals project in South Africa, with construction complete at the 996-m level station of Shaft 1.

The achievement, completed well ahead of the contractual schedule, according to Ivanhoe, positions the company to equip Platreef’s initial production shaft, if it chooses to proceed with phased development of the mine on the Northern Limb of South Africa’s Bushveld Complex.

Sinking was carried out by contractor Moolmans, with the project remaining ‘Fall-of-Ground’ incident free since shaft sinking operations began in July 2016, the company said. On top of this, in June 2020, Moolmans and the Platreef team achieved South Africa shaft sinking industry leader status in terms of safety performance, according to Ivanhoe, which owns 64% of the project through Ivanplats.

Ivanhoe’s Co-Chairmen, Robert Friedland and Yufeng “Miles” Sun, said: “Given the flurry of recent transactions in precious metals markets, we are actively exploring a number of options that can help us unlock Platreef’s extraordinary value for the benefit of all Ivanhoe stakeholders.

“After all, Platreef is among this planet’s largest precious metals deposits.”

Platreef now has a completed shaft within a few hundred metres of the initial high-grade mining zone, according to Friedland and Sun.

“We have a mining licence, we have water and we have a team of highly-skilled employees,” they said. “The deposit has enormous quantities of palladium, platinum, rhodium, nickel and copper; and it has more ounces of gold than many leading gold mines.”

They concluded: “Given the current precious metals environment, I am confident that the pending studies will showcase the exceptional economics that one would expect from such a thick, high-grade and flat-lying deposit.”

Ivanhoe is updating the Platreef project’s 2017 definitive feasibility study (DFS) to account for development schedule advancement since 2017 when the DFS was completed, as well as updated costs and refreshed metal prices and foreign exchange assumptions.

The DFS for Platreef covered the first phase of production at an initial mining rate of 4 Mt/y, estimating Platreef’s initial average annual production rate would be 476,000 oz of platinum, palladium, rhodium and gold, plus 21 MIb (9,525 t) of nickel and 13 MIb (5,897 t) of copper.

Concurrently, Ivanhoe is finalising a preliminary economic assessment for the phased development production plan for Platreef. The plan targets significantly lower initial capital to accelerate first production by using Shaft 1 as the mine’s initial production shaft, followed by expansions to the production rate as outlined in the 2017 DFS, Ivanhoe said.

“The re-evaluation is being done in parallel with the ongoing mine development work to access the thick, high-grade, flat-lying Flatreef deposit that was discovered in 2010 and outlined in the Platreef 2017 feasibility study,” it said.

The new auxiliary winder for the 7.25 m diameter Shaft 1, which is scheduled to be delivered to Platreef later this year, will be used to assist in equipping the shaft; and thereafter for logistics, shaft examination and auxiliary functions. The auxiliary winder will provide a second means of ingress and egress from the shaft after removal of the stage winder.

Shaft 1 is around 350 m away from a high-grade area of the Flatreef orebody, planned for bulk-scale, mechanised mining.

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

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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.

OZ Minerals, Loesche team up following West Musgrave vertical roller mill test work

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OZ Minerals, following a successful prefeasibility study of vertical roller mills (VRM) at the West Musgrave project in Western Australia, has signed a “Partnering Agreement” with Loesche.

The agreement with the leading original equipment manufacturer (OEM) of VRMs will help the company as it moves to the next phase of the project, OZ Minerals said.

“By working in a collaborative, innovative and transparent way, we believe we will deliver superior outcomes for the project when compared to more traditional ways of engaging with suppliers,” OZ Minerals said.

In November 2017, OZ Minerals and Cassini, which owns 30% of West Musgrave, announced that the West Musgrave project would progress to a prefeasibility study. This prefeasibility study timeline was extended in 2019 to complete a detailed evaluation of additional value-add opportunities, the most significant of which was the use of a dry VRM to reduce power consumption.

The study, released earlier this year, showed off plans for a 26-year open-pit mine with “bottom quartile cash costs” and average production of circa-28,000 t/y of copper and circa-22,000 t/y of nickel in concentrates, OZ Minerals said.

It also included details of an “innovative mineral processing plant” that would be built on site.

The grinding circuit for West Musgrave was expected to consist of two stages of crushing followed by two parallel VRMs treating nominally 5 Mt/y each. The second stage of crushing and VRMs replaced a traditional SAG mill, ball mill and pebble crushing circuit.

OZ Minerals explained in the study: “Vertical roller mills are widely used in the grinding of cement plant feeds and products, slag, coal and other industrial minerals, with thousands currently in operation worldwide. The mill has benefits in reducing power consumption by circa-15%, no ball charge grinding media, higher flotation recovery and can be ramped up and down in response to the availability of low-cost renewable energy.”

The VRM uses compression-style comminution principles taking 75 mm rock to flotation feed size in the one machine, according to OZ, adding that the application of the VRM had reduced processing costs and provided a circa-2% improvement in nickel recovery compared with a previous scoping study.

“The technology has been peer reviewed for West Musgrave by an independent expert and has been substantially de-risked through a series of pilot tests whereby 5 t of West Musgrave ore has been tested,” the company said.

Reviewing the prefeasibility study, OZ Minerals Chief Executive Officer, Andrew Cole, said: “We have been able to achieve a further significant reduction in carbon emissions and power demand through the adoption of vertical roller mills as the grinding mill solution and a flotation flowsheet which achieves metal recovery at a much coarser grind size than was previously considered in the design.

“This lower power usage has resulted in a reduction in operating costs, while the use of dry grinding from the vertical roller mills has also resulted in an improvement in nickel recovery.”

Another innovation the company plan to use at West Musgrave include the use of hybrid renewables that could include a combination of wind and solar energy, battery back-up, and diesel or gas.

Mining at West Musgrave is modelled to be conventional drill, blast, load and haul and is assumed to be contractor operated during the first five years of operation, transitioning to owner operate in year six.

The haulage fleet will comprise up to 25 220 t haul trucks and optionality is being maintained to allow for these trucks to be fully autonomous in the future, OZ Minerals said.