Tag Archives: COVID-19

NextOre’s magnetic resonance tech up and running at First Quantum’s Kansanshi

Australia-based NextOre is onto another ore sorting assignment with its magnetic resonance (MR) sensing technology, this time in Zambia at First Quantum Minerals’ Kansanshi copper mine.

NextOre was originally formed in 2017 as a joint venture between CSIRO, RFC Ambrian and Worley, with its MR technology representing a leap forward in mineral sensing that provides accurate, whole-of-sample grade measurements, it says.

Demonstrated at mining rates of 4,300 t/h, per conveyor belt, the technology comes with no material preparation requirement and provides grade estimates in seconds, NextOre claims. This helps deliver run of mine grade readings in seconds, providing “complete transparency” for tracking downstream processing and allowing operations to selectively reject waste material.

Having initially successfully tested its magnetic resonance analysers (MRAs) at Newcrest’s Cadia East mine in New South Wales, Australia, the company has gone onto test and trial the innovation across the Americas and Asia.

More recently, it set up camp in Africa at First Quantum Minerals’ Kansanshi copper mine where it is hoping to show off the benefits of the technology in a trial.

The MRA in question was installed in January on the sulphide circuit’s 2,800 t/h primary crushed conveyor at Kansanshi, with the installation carried out with remote assistance due to COVID-19 restrictions on site.

Anthony Mukutuma, General Manager at First Quantum’s Kansanshi Mine in the Northwestern Province of Zambia, said the operation was exploring the use of MRAs for online ore grade analysis and subsequent possible sorting to mitigate the impacts of mining a complex vein-type orebody with highly variating grades.

“The installation on the 2,800 t/h conveyor is a trial to test the efficacy of the technology and consider engineering options for physical sorting of ore prior to milling,” he told IM.

Chris Beal, NextOre CEO, echoed Mukutuma’s words on grade variation, saying daily average grades at Kansanshi were on par with what the company might see in a bulk underground mine, but when NextOre looked at each individual measurement – with each four seconds representing about 2.5 t – it was seeing some “higher grades worthy of further investigation”.

“The local geology gives it excellent characteristics for the application of very fast measurements for bulk ore sorting,” he told IM.

Mukutuma said the initial aim of the trial – to validate the accuracy and precision of the MRA scanner – was progressing to plan.

“The next phase of the project is to determine options for the MRA scanner to add value to the overall front end of processing,” he said.

Beal was keen to point out that the MRA scanner setup at Kansanshi was not that much different to the others NextOre had operating – with the analyser still measuring copper in the chalcopyrite mineral phase – but the remote installation process was very different.

“Despite being carried out remotely, this installation went smoother than even some where we had a significant on-site presence,” he said. “A great deal of that smoothness can be attributed to the high competency of the Kansanshi team. Of course, our own team, including the sensing and sorting team at CSIRO, put in a huge effort to quickly pivot from the standard installation process, and also deserve a great deal of credit.”

Beal said the Kansanshi team were supplied with all the conventional technical details one would expect – mechanical drawings, assembly drawings, comprehensive commissioning instructions and animations showing assembly.

To complement that, the NextOre team made use of both the in-built remote diagnostic systems standard in each MRA and several remote scientific instruments, plus a Trimble XR10 HoloLens “mixed-reality solution” that, according to Trimble, helps workers visualise 3D data on project sites.

“The NextOre and CSIRO teams were on-line on video calls with the Kansanshi teams each day supervising the installation, monitoring the outputs of the analyser and providing supervision in real time,” Beal said. He said the Kansanshi team had the unit installed comfortably within the planned 12-hour shutdown window.

By the second week of February the analyser had more than 90% availability, Beal said in early April.

He concluded on the Kansanshi installation: “There is no question that we will use the remote systems developed during this project in each project going ahead, but, when it is at all possible, we will always have NextOre representatives on site during the installation process. This installation went very smoothly but we cannot always count on that being the case. And there are other benefits to having someone on site that you just cannot get without being there.

“That said, in the future, we expect that a relatively higher proportion of support and supervision can be done through these remote systems. More than anything, this will allow us to more quickly respond to events on site and to keep the equipment working reliably.”

Austmine to offer ‘complete’ industry access to conference and exhibition

Austmine is ensuring all participants from the Australian and international resources sector can gain access to the upcoming Austmine Conference and Exhibition in Perth, Western Australia, irrespective of COVID-19 travel restrictions.

The mining equipment, technology and services industry organisation is hosting its conference and exhibition from May 25-27, with expectations it will be one of the largest gatherings of the industry since COVID-19 emerged.

Austmine CEO, Christine Gibbs Stewart, said Austmine knows how important this event is to the industry and wants to ensure everyone is able to get complete access, even in these uncertain times.

“To make sure no one misses out, if borders close in your state during the conference, we will be providing an alternate conference experience virtually that will give you access to view and engage with the conference from your home or office,” Gibbs Stewart said.

“We understand virtual attendance is not quite the same as getting to experience the in-room atmosphere and opportunity for conversation and collaboration, which is why we are giving 25% refunds to all who are pushed to join virtually due to border restrictions.

“We are, however, encouraging everyone to purchase full-access tickets to Austmine 2021 to embrace the full experience as we hear from industry experts and explore the importance of optimising our technology, processes and collaboration across the industry.

“We are really conscious of the unprecedented times we face, and although travel is opening up and restrictions are easing, we are wanting to implement a solution ahead of time should any further restrictions arise.”

More than 80 exhibiting companies will attend the 2021 conference, along with a line-up of world-class speakers, interactive workshops, educational and networking opportunities, live demonstrations, the collaborative Ideas Exchange, Meet the Miners and the Austmine Industry Leaders’ Dinner and Awards, Austmine says.

International Mining is a media sponsor of Austmine 2021

Interact Analysis forecasts slow haul truck electrification uptake in open-pit mining

The electric revolution looks to be well and truly underway in the mining space, with underground mines of all sizes planning, trialling, or ordering various battery-electric machines to help them decarbonise their operations. Yet, the latest report on the off-highway vehicle market from Interact Analysis has indicated the transition above ground will take a little longer than many anticipated.

Homing in specifically on the 85-t-plus global hauler/dump truck market – broadly applicable to the medium-large construction space and the small-large open-pit mining sector – the market research firm laid out estimates for the annual number of new truck deliveries to 2029.

The surprising aspect of this research was the continued dominance of internal combustion engine (ICE) vehicle deliveries over this time frame.

The team at Interact Analysis expected the adoption rate/market share to go from 100% in 2020 – when 1,330 new vehicles were delivered – to 96.2% in 2029 – when it expected 1,716 units to be delivered.

The growth is slightly extreme in this comparison, but is partially accounted for by a drop off in deliveries in 2020 due to the effects of COVID-19. For reference, in 2019, 2,065 units were delivered.

Included within the ICE stats are biofuel vehicles, which have been gaining prominence in the mining space as miners realise they can both reduce diesel costs and emissions by incorporating biofuels into their operating mix.

Over the same time frame – 2020-2029 – the analysts see “hybrid” trucks commanding zero percent market share, with no sales.

Fully-electric trucks fare better, moving from zero deliveries in 2020 to two in 2021, five in 2022, six in 2023; to 72 in 2028 and 67 in 2029. The fully-electric adoption rate moves from 0% in 2020 to 3.8% in 2029.

Among these new fully-electric dump trucks is an XCMG EDF531 90 t battery-electric truck that was on show at the Bauma China show late last year (pictured below).

Jan Zhang, Senior Research Director at Interact Analysis, based in China, said this dump truck has already been delivered to a customer.

“In fact, quite a few dump fully-electric trucks below 100 t have already been used in China (in Guangdong),” she told IM. “Many of these have payloads of below 60 t, but a few are 90 t, and are in trial runs, and a few have also been exported to New Zealand, using the LiFePO4 battery from CATL.”

There has been much talk about hydrogen haul trucks taking hold in the mining space. This has been catalysed by Anglo American’s plans to test a 291 t fuel cell electric vehicle, a conversion to hydrogen fuel cell and lithium battery operation of a diesel-powered Komatsu 930E, at the Mogalakwena platinum mine in South Africa. If successful, these tests could lead to a rollout of 40 FCEVs across the global miner’s operations, it says.

Despite this, Interact Analysis’ research has no plus-85 t payload hydrogen trucks included in its forecasts to 2029.

Alastair Hayfield, Senior Research Director at Interact Analysis, based in the UK, explains: “Our statistics only look at new builds and not retrofits. My understanding is that the Anglo American vehicles would be retrofit (although there is limited detail at this point).

“Should some be new build, then we would update our forecast accordingly once we have better visibility.”

It’s worth asking the question: what about hydrogen trucks in mining beyond 2029?

Zhang said: “At present, mining trucks are mainly used in medium and large-scale coal and metal mines, and the use scenario is mainly for downhill heavy payload applications. That is to say where mineral resources are situated in a high up location, and it is necessary to load them from the mountain to the conveyor belt or transfer vehicle (the short distance transportation path is generally 2-3 km).”

She said mining truck electrification is mainly driven by two factors, with the first being operational cost advantages.

Jan Zhang, Senior Research Director at Interact Analysis, based in China

“For example, a mine truck with a total weight of 90 t will cost $45,000-75,000 in standard fuel annually, whilst the cost of electricity is only a third of the cost of fuel under the same circumstances, which means that $30,000-45,000 can be saved in the annual cost, not to mention other costs which are also higher for ICE mine trucks such as repair and maintenance,” she said.

The second factor is environmental protection and policy promotion.

“In China, the ‘National Green Mine Construction Specification’, issued by the Ministry of Natural Resources, has been implemented since October 2018,” Zhang explained. “This measure will surely help to grow the market share of hydrogen trucks in China, although the overall percentage will remain small.”

The last category included in Interact Analysis’ research was “Others” in the global hauler/dump truck market for 85-t-plus vehicles.

No deliveries for this category were registered in 2020, but the company anticipates one delivery in 2021, followed by three in 2022 and five in 2023. This gets as high as eight deliveries in 2025, but, by the end of the forecast period (2029), this category still commands 0.0% of the total.

So, what trucks fit into this category?

Hayfield explained: “We’re talking about diesel-electrics that will enter service into a trolley line operation – we essentially have to make an estimate on how we think the vehicle will predominantly be used. This is analogous to what we do in our on-highway research where we have to make estimates on how class 8 trucks are used for different applications ie long haul, distribution, vocational applications.”

This is not to say there will be no trolley assist trucks coming into the mining space, but, as far as Interact Analysis is concerned, these will not be new trucks coming out of the factory destined to head onto trolley lines. They will more likely be AC drive trucks that are retrofitted later for trolley assist operation.

When consolidated, these numbers show an underlying trend.

Back in 2019, there were 2,065 truck units delivered to the market in this 85-t-plus category, but, even out to 2029, this level is not reached, according to Interact Analysis.

Alastair Hayfield, Senior Research Director at Interact Analysis, based in the UK

In 2020, total deliveries dropped to 1,330 and, in 2021, Interact Analysis sees this rising to 1,545 units. A continual rise is expected in the years following, but it only reaches 1,783 in 2029.

What about beyond this timeframe?

Hayfield answered: “You have two fundamental pressures: a growing, resource-intensive population and a need to re-use/cut consumption because of environmental and/or legislative pressure. I suspect we will continue to see the growth of new mines throughout the 2030s in developing regions, fuelling demand for new trucks. However, I suspect we will see increasing pressure in Europe and North America on sustainability and the need to re-use materials and, hence, a slowing in the opening of new mines.”

This means demand for new trucks could start to drop during the 2030s in Europe and North America, he deduced.

This is not an exhaustive look at trends in the open-pit mining dump truck market – it is more of a taster – but Interact Analysis plans a detailed, mining specific study later in 2021. Such analysis could include forecasts for the retrofit market, providing the complete picture mining industry onlookers are after.

FLSmidth high density thickeners optimise recoveries at DRC copper-cobalt mine

FLSmidth says it has delivered a thickener solution to help double production rates at one of the world’s largest copper and cobalt producers in the Democratic Republic of the Congo (DRC).

The order for the solution, which included six of FLSmidth’s high density thickeners, was placed in 2020, with delivery now completed.

The mine already had FLSmidth thickeners on site, with the company’s proposal for the mine’s expanded requirements  based on test work to confirm the characteristics of the material to be treated, according to FLSmidth General Manager Projects and Account Sales, Howard Areington.

“The tests confirmed that we could use a similar design to what we had installed on the mine some years previously,” he says. “This solution included six counter current decantation (CCD) thickeners and one pre-leach thickener, each measuring 31 m in diameter.”

These units deliver high solids underflow to optimise the recovery of dissolved metals, according to FLSmidth. In addition to the steeper floor slope, these thickeners were designed with a high torque ring gear drive design, with high tolerances that make for minimal maintenance over long periods of time, the company says.

“Our high density thickener design ensures consistently high underflow densities which allows the operator to sustain high production rates and better recoveries,” Areington says.

These CCD thickeners are manufactured from LDX2101 duplex stainless steel. This provides mechanical benefits without compromising chemical resistance, allowing the mass of each unit to be reduced, the company explained. The pre-leach thickener, which was not exposed to corrosive conditions, is constructed from carbon steel.

“We also designed and supplied five impurities removal thickeners, which are high rate thickeners, also in LDX2101 stainless steel,” Areington says. “The sizes of these units ranged from 20 to 30 m in diameter.”

Fabrication of the equipment was carried out in South Africa while accommodating the demands of the COVID-19 lockdown, which required careful planning and flexibility. With components and platework delivered to site, the welding and construction was conducted by the mine with installation assistance from FLSmidth and its agent in the region.

Hycroft Mining continues evaluation of novel sulphide heap oxidation/leach process

After testing out a “novel” oxidation and leaching process at the Hycroft Mine in Nevada, USA, Hycroft Mining Holding Corp is making plans to go back to a conventional oxide leaching setup in 2021.

The company produced 27,392 oz of gold and 178,836 oz of silver in 2020, an almost three-fold increase over 2019. It hit these numbers while operating at a pre-commercial scale using the novel process, which oxidises sulphides ahead of leaching.

It is now planning for run-of-mine production of 45,000-55,000 oz of gold and 400,000-450,000 oz of silver in 2021 using conventional cyanide heap leach.

It is anticipated that mining in the first four months of 2021 will be performed using the existing Hycroft fleet and a rental fleet, moving approximately 1.5 Mt/mth of ore and waste. For the remainder of the year, Hycroft intends to mine some 500,000 t of oxide and transitional ore and waste per month with a more cost-effective mining fleet.

Diane R Garrett, President & Chief Executive Officer, reflected on the results: “2020 was an important year for Hycroft as the company continued to focus on the restart of the Hycroft Mine. Throughout the year, we advanced work on the proprietary two-stage sulphide heap oxidation and leach process and made several important findings that will need to be addressed prior to our implementing the novel technology on a commercial scale.

“In 2021, we expect to mine predominantly oxide and transition material, which are more economic when treated using a conventional run-of-mine heap leaching method, which gives us the opportunity to continue to refine the operating parameters and flowsheet for the new heap leach pad and novel process. While the company continued to make significant progress in better understanding this proprietary process and its application on a commercial scale, the past year also presented some operational challenges, including learning to navigate in a newly emerged COVID-19 world.”

In the last few months, Hycroft says it has worked alongside consultants to identify and investigate opportunities for improvements in operating parameters for the two-stage sulphide heap oxidisation and leach process. The result of the work to date has identified several items that were not considered or included in the original plan and design but are critical to the success of this process. These findings include:

  • Adding a forced air injection system for the leach pad which is a key component of the oxidation process;
  • Developing a system for segregating solution flows to and from the heap leach pad to avoid co-mingling of solutions among heap lifts and ore processing stages that negatively impact recoveries and conditions on the leach pads;
  • Identifying that the finer crushed material requires agglomeration in order to achieve optimal permeability and gold/silver recoveries;
  • Understanding that higher soda ash, caustic soda, and cyanide consumption will be required which Hycroft experienced throughout the 2020 pre-commercial test pad programs and recently confirmed through the review of the test work;
  • Determining that some transitional ores are more economically attractive when processed as direct leach, run-of-mine material; and
  • Concluding that additional variability metallurgical and mineralogy studies will be required to better understand each of the geometallurgical domains in the orebody. While there was some variability work completed in the past, the recent test work has revealed that additional variability test work and compositing is necessary to fully understand the geometallurgy of each domain, and that additional sampling, including sampling below the water table where the predominance of the sulphide resources exist, is required given the complexity and variability of the large orebody.

The additional variability test work will also include detailed mineralogy studies as it is important to understand the role other minerals may play in the overall oxidation process and to enhance Hycroft’s ability to measure oxidation rates accurately and consistently, it said.

The team at Hycroft has developed an approximate $10 million program for drilling and additional metallurgical and mineralogical studies in 2021. This program of work has been approved by the Board of Directors of Hycroft and can be funded from existing cash and Hycroft’s current operating plans.

Hycroft expects to mine and stockpile at least 300,000 tons (272,155 t) of sulphide ore in 2021 that, once sufficient additional work on the novel process has been completed, will be available for testing to further refine operating parameters and measure its performance for large scale application of the oxidation heap leach.

Garrett added: “2021 is a foundational year designed to advance the work necessary in preparation for larger-scale sulphide operations. The team is working diligently to optimise current and future heap leach mine plans and to evaluate all opportunities for more profitable mine plans in the near and medium term. This work involves taking a ‘ground up’ approach working from the orebody out. The company’s prior plan was developed using a $1,200/oz gold price pit shell which leaves profitable ore behind in the current gold and silver price environment. By running pit shells at recent gold and silver prices, we have identified additional areas of oxide mineralisation that can generate cash flows over the next several years and we have already begun to identify areas of higher-grade mineralisation that will become important for mine sequencing and further improving cash flows prior to accessing sulphide material.”

As the company considers life-of-mine development and planning for the Hycroft deposit, particularly in the current gold and silver price environment, Hycroft says it is prudent to evaluate proven processing technologies for treating some ore types that may be more profitable than only using the two-stage sulphide heap oxidation and leaching process.

Potential opportunities being examined by the company in 2021 include: developing an understanding of the grade range distribution of the sulphide material; completing on-going work on the higher-grade areas of Hycroft; and following up on historical high-grade intercepts.

In order to capitalise on these potential opportunities, which take advantage of the current commodity price environment, Hycroft believes that it should also evaluate the benefits of a multi-process operation. Long-term operating scenarios may include conventional run-of-mine cyanide heap leaching for the oxide and transitional material, sulphide heap oxidation and leaching using the novel process, and an appropriately sized milling and flotation plant for processing the higher-grade ranges of sulphide material.

“The company believes that the plan it has put in place for 2021 will provide the new team the time to fully consider and evaluate these opportunities and make any necessary changes to improve the leach pads, process plants and process flowsheet, maintain and develop its workforce, and advance the project, in order to further enhance the value of the project,” it said. “As the test work advances and alternative processes are considered, the company expects to perform technical studies and trade-off evaluations which may result in an updated feasibility study.”

Master Drilling continues diversification plan in uncertain market

Master Drilling Group continued to add to its client and service base over the course of 2020, with bright spots reported in exploration drilling and the West Africa gold sector.

Its 2020 financials were hit by COVID-19, with revenue dropping 17% year-on-year to $123.1 million and operating profit declining to $12.3 million, from $24.1 million in 2019.

Danie Pretorius, CEO of Master Drilling, said: “Master Drilling’s overall performance for the year was weighed down by the weak global economic growth environment entering 2020, which was compounded by the material impact of COVID-19, across the 23 countries in which we operate, from a human, financial and operational perspective.

“Although the group experienced a significant decline in revenue in the South American operations, primarily due to government-imposed COVID-19 restrictions, this was offset by regions such as India, Africa and Scandinavia which remained operational and received various stimulus packages.”

Despite a decrease in revenue, the company’s net cash generation increased 72.7% to $25.5 million as it contained capital expenditure by balancing maintenance with emerging opportunities.

In the second half of the year, Master Drilling was awarded new exploration projects and mobilised an additional fleet to service existing clients, with a considerable turnaround in drilling and exploration activity becoming more apparent and creating a healthy pipeline, it said.

Around a year ago, Master Drilling fulfilled the conditions to acquire Geoserve Exploration Drilling, increasing the South Africa-based company’s ability to offer exploration drilling, reverse circulation drilling, geotechnical investigations and grade control drilling services.

Its commitment to Africa saw the continent become the largest contributor to the group in terms of revenue and profits over the course of the year. Aggressive expansion into West Africa continued as part of the group’s diversification strategy, with a specific focus on gold, which has seen a surge in demand since 2019.

Master Drilling also continued to grow its presence in new markets, including Australia, Russia and Central Asia. It secured new contracts with a focus on raiseboring and mechanised mining services, too.

As at December 31, 2020, Master Drilling’s sales pipeline totalled $539.9 million with a stable order book of $212.8 million (2019: $142.1 million).

“In the short to medium term, the sales pipeline is expected to normalise and increase with further tactical acquisitions and joint ventures supporting performance,” it said. “Opportunities to diversify outside of the traditional drilling business into areas such as artificial intelligence will also continue.”

Although capital has been tightly managed in response to the uncertain environment, Master Drilling says technological innovation remains a key priority for the company.

Aligned to this, Master Drilling announced a 40% investment in AVA Solutions, a specialist in data-driven mining fleet management solutions, this month.

Commenting on the investment, Pretorius said: “Our recent investment in AVA is aligned with our strategy to diversify our services and invest in businesses that help us meet our clients’ demand for increased mechanisation and digitisation. Other opportunities with low capital requirements and short return cycles are currently under review.”

He concluded on the annual results: “Although the shape of recovery remains uncertain, we have seen a turnaround in the past six months across the commodities and regions that we are already exposed to. Having made significant investments in our fleet, technology and geographical diversification over the past couple of years, we are now positioned to capitalise on the predicted commodities bull run without requiring additional capital investment.”

eHPCC: the future of grinding in mining?

A lot has been made of the potential of high pressure grinding rolls (HPGRs) to facilitate the dry milling process many in the industry believe will help miners achieve their sustainability goals over the next few decades, but there is another novel technology ready to go that could, according to the inventor and an independent consultant, provide an even more effective alternative.

Eccentric High Pressure Centrifugal Comminution (eHPCC™) technology was conceived in 2013 and, according to inventor Linden Roper, has the potential to eliminate the inefficiencies and complexity of conventional crushing and/or tumbling mill circuits.

It complements any upstream feed source, Roper says, whether it be run of mine (ROM), primary crushed rock, or other conventional comminution streams such as tumbling mill oversize. It may also benefit downstream process requirements through selective mineral liberation, which is feasible as the ore is comminuted upon itself (autogenously) in the high pressure zone via synchronous rotating components. Significant product stream enrichment/depletion has been observed and reported, too.

As IM goes to press on its annual comminution and crushing feature for the April 2021 issue – and Dr Mike Daniel, an independent consultant engaged by Roper to review and critique the technology’s development, prepares a paper for MEI Conferences’ Comminution ’21 event – now was the right time to find out more.

IM: Considering the Comminution ’21 abstract draws parallels with HPGRs, can you clarify the similarities and differences between eHPCC and HPGR technology?

MD & LR: These are the similarities:

  • Both offer confined-bed high-pressure compression comminution, which results in micro fractures at grain boundaries;
  • Both have evidence of preferential liberation and separation of mineral grains from gangue grains at grain boundaries; and
  • Both have an autogenous protective layer formed on the compression roll surfaces between sintered tungsten carbide studs.

These are the differences:

  • eHPCC facilitates multiple cycles of comminution, fluidisation and classification within its grinding chamber, retaining oversize particles until the target product size is attained. The HPGR is a single pass technology dependent on separate materials handling and classification/screening equipment to recycle oversize particles for further comminution (in the event subsequent stages of comminution are not used);
  • Micro factures around grain boundaries and compacted flake product that are created within HPGRs need to be de-agglomerated with downstream processing either within materials handling or wet screening. In some instances, compacted flake may be processed in a downstream ball mill, whereas, in eHPCC, preferential mineral liberation is perfected by subsequent continuous cycles within the grinding chamber until mineral liberation is achieved within a bi-modal target size (minerals and gangue). The bi-modal effect differs from ore type to ore type and the natural size of the minerals of interest;
  • The preferential liberation of mineral grains from gangue grains generally occurs at significantly different grain sizes, respectively, due to the inherent difference in progeny hardness. eHPCC retains the larger, harder grains, hence ensuring thorough stripping/cleaning of other grain surfaces by shear and attrition forces;
  • eHPCC tolerates rounded tramp metal within its grinding chamber, however does not tolerate high quantities of sharp, fragmented tramp metal that create a non-compressible, non-free-flowing bridge between roll surfaces, which risks the damage of liner surfaces;
  • The coarse fraction ‘edge effect’ common in HPGR geometry is not an issue with eHPCC. In fact, the top zone of the eHPCC grinding chamber is presumed to be an additional portion of the primary classification zone within the grinding chamber. The oversize particles from the internal classification process are retained for subsequent comminution;
  • The maximum size of feed particle (f100) entering the eHPCC is not limited to roll geometry as is the case with HPGRs (typically 50-70 mm). eHPCC f100 is limited to feed spout diameter (for free flow) and dependent of machine size ie eHPCC-2, -5, -8 and -13 are anticipated to have f100 60 mm, 150 mm, 240 mm and 390 mm, respectively. The gap between rolling surfaces is greater than the respective f100; and
  • eHPCC technology shows scientifically significant product stream enrichment.

IM: What operating and capital cost benefits do you envisage when compared with typical HPGR installations?

MD & LR: Both operating and capital cost benefits of the eHPCC relative to HPGR technology are due to the eHPCC not requiring the pre-crushing and downstream classification equipment required by HPGRs.

The eHPCC operating cost benefits are associated with eliminating maintenance consumables, downtime, reliability issues and energy consumption associated with the equivalent HPGR downstream equipment listed above.

The eHPCC capital cost benefits are associated with eliminating the real estate (footprint) and all engineering procurement and construction management costs associated with the equivalent HPGR upstream/downstream equipment listed above. eHPCC flowsheets are likely to be installed as multiple ‘one-stop’ units that maintain high circuit availability due to ongoing cyclic preventative maintenance.

IM: Where has the design for the eHPCC technology come from?

LR: It was invented in early 2013 by me. I then pioneered proof-of-concept, prototyping, design and development, culminating in operational trials in a Kazakhstan gold mine in 2020. A commercial-grade detailed design-for-manufacture has since been undertaken by a senior team of heavy industry mechanical machine designers and engineers.

IM: In your conference abstract, I note that the eHPCC technology has been tested at both laboratory and semi-industrial scale with working prototypes. Can you clarify what throughputs and material characteristics you are talking about here?

LR: The first iteration of the technology, eHPCC-1, was tested at the laboratory scale from 2013-2015. This proof-of-concept machine successfully received and processed magnetite concentrate, copper-nickel sulphide ore, alkaline granite, marble and a wolfram clay ore dried in ambient conditions. The typical throughput was between 200-400 kg/h depending on the feed size, particle-size-reduction-ratios (dependent of grain size) and target product size. The feed size was limited to a maximum of 25 mm to ensure free flow of feed spout.

Alkaline granite: eHPCC-2 coarse product (left) and fine product (right)

MD & LR: From 2016-2020, we moved onto the semi-industrial scale testing with the eHPCC-2 (two times scaled up from eHPCC-1). This was designed for research and development (R&D) and tested on magnetite concentrate, alkaline granite, and hard underground quartz/gold ore. The throughput capabilities depended on the geo-metallurgical and geo-mechanical properties of feed material, such as particle size, strength, progeny (grain) size and particle size-reduction-ratios (subject to confined bed high pressure compression). Larger-scale machines are yet to be tested against traditional ‘Bond Theory’ norms.

The eHPCC, irrespective of the outcomes, should be evaluated on its ability to effectively liberate minerals of interest in a way that no other comminution device can do. The maximum feed size, f100, at the gold mine trials was limited to 50 mm to ensure free flow through the feed spout. R&D culminated in pilot-scale operational trials at the Akbakai gold mine (Kazakhstan), owned by JSC AK Altynalmas, in 2020, where SAG mill rejects of hard underground quartz/gold ore were processed. The mutual intent and purpose of the tests was to observe and define wear characteristics of the eHPCC grinding chamber liners (roll surfaces). These operational trials involved 80% of the feed size being less than 17 mm and a variety of targeted product sizes whereby 80% was less than 1 mm, 2 mm, 2.85 mm and 4.8 mm. The throughput ranged from 1-5 t/h based on the size.

IM: What throughputs and material characteristics will be set for the full-scale solution?

LR: There will be a select number of standard eHPCC sizes. Relative to the original eHPCC-1, the following scale-up factors are envisaged: -2, -3, -5, -8, and -13. These are geometrical linear scale-up factors; the actual volumetric capacity is a cube of this factor, with adjustments for centripetal acceleration. Currently -13 times seems to be the maximum feasible size of the present detailed design philosophy, but there are no foreseeable limitations in terms of feed materials with exception to moist clay. Clay was successfully processed after drying the feed in ambient temperatures during testing. Further testing of moist clays blended with other materials that can absorb the moisture as they comminute would be desirable.

IM: Other HPGRs can also be equipped with air classification technology to create dry comminution circuits. What is the difference between the type of attrition and air classification option you are offering with the eHPCC?

MD & LR: Two modes of comminution occur in the particle bed of eHPCC repetitively and simultaneously. First, confined bed pressure compression breakage occurs at a macro level that promotes shear/compression forces greater than the mineral grain boundaries. Second, Mohr-Coulomb Failure Criteria (shear/attrition) that completes the separation of micro fractures on subsequent cycles takes place.

The nip angle between the rotating components of eHPCC technology never exceed 5°. During the decompression and fluidisation portion of the cycle, the softer species – which are now much smaller – are swept out of the fluidised particle bed against centrifugal and gravitational forces by process air. The larger species, influenced by centripetal acceleration, concentrate at the outer diametric and lower limits of the conical rotating grinding chamber, continuing to work on each other during each subsequent compression phase.

HPGRs are limited to one single-pass comminution event, requiring downstream external classification and subsequent recycling/reprocessing of their oversize and/or flake product.

IM: How will it improve the mineral liberation and separation efficiency compared with other grinding solutions that combine both?

MD: eHPCC technology could compete with the Vertical Roller Mill and Horomill, however, eHPCC is likely to be more compact with high intensity breakage events contained within the all-inclusive system of breakage, classification and removal of products.

IM: When was it most recently tested and over what timeframe?

LR: The eHPCC-2 pilot plant was mobilised, setup and commissioned in March 2020, but its operation was suspended until June 2020 due to COVID-19 quarantine restrictions and a need to cater to abnormal amounts of ball fragments in the feed, the latter of which pushed the treatment of tramp metal to the extreme. The machine operated for the months of June and July using liners constructed of plasma transferred arc welded (PTAW) tungsten carbide (TC) overlay. During this period, a total of 795 t was processed at various targeted product sizes, with, overall, an average throughput of 3 t/h (nominally 265 operating hours) processed.

Side view of pilot system including feed hopper and weigh-scale feeder (right), feed conveyor (middle foreground), control and auxiliaries (middle background), eHPCC-2 (left foreground), dust bag-house (left background) and product conveyor and stockpile (not shown left background)
Front-end loader filling feed hopper with SAG mill rejects f80 18 mm

The PTAW-TC overlay was deemed unsustainable as it was consumed rapidly and demanded continuous rebuilding due to the high pressure intensive abrasive wear on the convex cone. The pilot plant operation was mostly suspended during the month of August while an alternative tungsten carbide studded liner, analogous to HPGR studded rolls, was manufactured for simulating a trial of this studded liner philosophy. The studded liner philosophy was operated in the eHPCC-2 in Kazakhstan for sufficiently long enough to ascertain the creation of the autogenous protective wear layer of rock between the studs, with the simulation trial deemed a success. The design philosophy shall be adapted on the commercial-grade eHPCC.

eHPCC-2 TungStud™ as-new (left) high-pressure-air-cleaned (middle) and brushed (right)

The pilot plant was demobilised from the Akbakai site laydown area on September 10, 2020, to release the area for construction of a non-related plant expansion. The operational experiences of the pilot plant at Akbakai provided valuable knowledge and experience pertaining to mechanical inertia dynamics and design for eliminating fatigue within eHPCC components.

IM: Aside from the test work on trommel oversize at the Kazakhstan gold mine, where else have you tested the technology?

LR: eHPCC has no other operational experiences so far. Investment and collaboration from the industry to progress the commercialisation of eHPCC is invited. The commercial-grade eHPCC-2.2 is designed and ready for manufacture.

IM: Is the technology more suited to projects where multiple streams can be produced (fines, coarse piles, etc)?

LR: eHPCC is configurable to meet the demands and liberality of a diverse spectrum of feed materials and the potential downstream extractive processes are complementary to eHPCC product streams. Therefore, it would be incorrect to categorise it as more suitable in any one niche; it is configurable, on a case-by-case basis, to meet the liberality of the specific progeny of the feed.

IM: What energy use benefits do you anticipate by creating a one-step comminution and classification process over the more conventional two-step process?

MD & LR: The energy saving benefits include:

  • Elimination of tumbling mill grinding media consumption;
  • Elimination of the liberal wastage of randomly directed attrition and/or impact events that indiscriminately reduce the size of any/all particles (gangue or precious mineral) with the conventional tumbling mill; and
  • Elimination of energy consumption of the materials handling systems between the various stages of comminution and classification, be it dry belt conveying, vibrating screens, classifiers, cyclone feed pumps, cyclones and their respective recirculating loads that can be upward of 300% of fresh feed.

IM: Do you anticipate more interest in this solution from certain regions? For instance, is it likely to appeal more to those locations that are suffering from water shortages (Australia, South America)?

MD & LR: We suspect the initial commercialisation growth market to be from base metals producers seeking to expand or retire existing aged/tired comminution classification capacity, followed by industry acknowledgement of the technology’s potential to shift the financial indicators of other potential undeveloped projects into more positive territory. This latter development could see the technology integrated into new projects.

In general, the technology will appeal to those companies looking for more efficient dry comminution processes. This is because it offers a pathway to rejection of gangue at larger particle sizes, early stream enrichment/depletion and minimal overgrinding that creates unnecessary silt, which, in turn, hinders or disrupts the integrity of downstream metallurgical extraction kinetics, and/or materials handling rheology, and/or tailings storage and management.

LR: There are a number of rhetorical questions the industry needs to be asking: why do we participate in the manufacture and consumption of grinding media considering the holistic end-to-end energy and mass balance of this (it’s crazy; really why?)? Why do we grind wet? What are the barriers preventing transition from philosophising over energy efficiency, sustainability etc and actually executing change? Who is up for a renaissance of bravely pioneering disruptive comminution and classification technology in the spirit of our pioneering forefathers?

The more these questions are asked, the more likely the industry will find the solutions it needs to achieve its future goals.

Dr Mike Daniel’s talk on eHPCC technology will be one of the presentations at the upcoming Comminution ’21 conference on April 19-22, 2021. For more information on the event, head to https://mei.eventsair.com/comminution-21/ International Mining is a media sponsor of the event

Vuzix Smart Glasses keep Rio global teams connected at Oyu Tolgoi Underground

Rio Tinto has deployed Vuzix Smart Glasses at the Oyu Tolgoi copper-gold mine in Mongolia to continue progressing the development of the underground project in the face of travel restrictions tied to COVID-19.

Vuzik, a supplier of smart glasses and augmented reality technology and products, says the company is using its smart glasses to enable technical experts from all over the world to work with local teams on the underground project.

Rio, in its 2020 Annual Report, said it had been increasing its use of drones and mine pit cameras, and introduced video headsets (including smart glasses) to conduct visual inspections of tailings facilities and equipment while complying with travel restrictions and physical distance requirements.

“Vuzix Smart Glasses usage continues to expand across an ever-widening array of industry verticals,” Paul Travers, Vuzix President and Chief Executive Officer, said. “Companies like Rio Tinto, which is a global leader in its field, continue to provide validation of the value and effectiveness of our products in real world situations.”

Anglo’s Quellaveco to receive the coarse particle recovery treatment

Anglo American has approved the construction of a coarse particle recovery (CPR) plant at its in-development Quellaveco copper project in Peru.

The announcement came within the company’s 2020 financial results, which showed Anglo generated underlying EBITDA of $9.8 billion and a profit attributable to equity shareholders of $2.1 billion for the year.

CPR, Anglo says, is one of many significant breakthrough technology initiatives that has the potential to increase throughput and productivity, while simultaneously reducing environmental footprint, through rejection of coarse gangue (near-worthless waste material), dry stacking of sand waste, minimising the production of traditional tailings and reducing overall water consumption.

The CPR plant signoff at Quellaveco follows a full-scale demo plant installation at the company’s El Soldado mine in Chile – which is ramping up to full capacity by mid-2021 – and the decision to construct a full-scale system at the Mogalakwena North PGM concentrator in South Africa.

The El Soldado plant used the HydroFloat™ CPR technology from Eriez’s Flotation Division. Here, a single 5 m diameter HydroFloat cell, the largest in the world, treats 100% of mill throughput, with the objective of proving the waste rejection process at full scale.

Anglo said of the Quellaveco CPR plant: “This breakthrough technology will initially allow retreatment of coarse particles from flotation tailings to improve recoveries by circa-3% on average over the life of the mine. This investment will also enable future throughput expansion which will bring a reduction in energy and water consumption per unit of production.”

The capital expenditure of the CPR project is around $130 million, with commissioning of the new plant expected in 2022. DRA Global previously carried out a feasibility study for the CPR plant at Quellaveco.

In terms of Quellaveco project progress, Anglo said today that, despite the COVID-19-related slowdown, first production was still expected in 2022. This was, in part, due to the excellent progress achieved prior to the national lockdown, and based on optimised construction and commissioning plans, Anglo said.

Key activities in 2021 include the start of pre-stripping, which will see the first greenfield use of automated hauling technology in Peru; progressing construction of the primary crusher and ore transport conveyor tunnel to the plant; completion of the 95 km freshwater pipeline that will deliver water from the water source area to the Quellaveco site; completing installation of the shells and motors for both milling lines; and completion of the tailings starter dam.

The mine, owned 60% by Anglo and 40% by Mitsubishi Corp, comes with a production blueprint of 300,000 t/y over the first 10 years of the mine.

From compliance to commitment: a key opportunity for the global mining industry

In the lead up to the AusIMM Underground Operators Conference in March, Roy Slack, immediate past President of the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) and Underground Operators keynote speaker, has shared his insights on the future of underground mining and the positive impact technology can have on safety.

With 35 years of global experience in mine construction, design and development, Slack is passionate about securing the mining industry’s place as a global leader for change.

“Our industry is on a journey from compliance to commitment,” he said. “From a state where we strive to just meet regulatory requirements, to a place where we meet and far surpass those requirements – not because we are legally required to do so, but because it is a moral imperative.”

Slack discusses how young professionals have an exciting opportunity to build the future of underground mining.

“Today’s youth are entering the industry, or have the opportunity to enter our industry, at a time of great change,” he said. “Change in technology, change in how we deal with people, change in the overall business model that is mining.”

As the mining industry rapidly transforms with new technologies and exciting innovations, Slack believes the whole sector needs to get on board with a fresh way of thinking.

“We need people that thrive on change, that embrace and know what to do with it.”

After such a challenging year, Slack is confident in the resiliency of the mining industry.

“What we continue to see during this pandemic is our industry recognised as an essential service, and mining companies taking the lead when it comes to establishing protocols to protect their people from the virus,” he said.

The industry’s reaction to COVID-19 displayed its agility in adjusting to circumstances, Slack says.

“Productivity did not suffer, and employees were able to better deal with work and home needs.”

Slack has been active in numerous safety initiatives over the years, as well as being appointed to the Province of Ontario’s first Prevention Council, advising the government on workplace safety. He also chairs the CIM Safety Committee.

He says new technologies will create a real sense of support and safety in the workplace for all professionals.

“I am excited about the huge potential of emerging technologies to make our workplaces not just safer, but safe,” he said. “Technology has always been an important part of safety, but the more recent applications of the technology available to us add a whole new perspective on our journey to zero injuries.”

Slack looks forward to the positive and safer benefits technology can create for on-site workers, with the pandemic in some cases speeding up the implementation of automation, remote operations and more.

Ultimately, Slack sees best practice in safety as a three-part equation: “Process, culture and technology; together protecting our people and ultimately achieving a safe workplace,” he said.

AusIMM’s Underground Operators Conference will be held from March 15-17, 2021, via a hybrid format, which offers an opportunity for delegates to attend face-to-face in Perth, Australia or online.

Find out more at https://www.ausimm.com/conferences-and-events/underground-operators

International Mining is a media sponsor of the event