Tag Archives: tailings dams

Komatsu iMC dozers, drone tech help RHT Contracting revolutionise tailings dam build

When long-time friends Joe Riccardo, Mike Heddon and Mark Tyler set up RHT Contracting in mid-2018, they knew they needed a winning edge when bidding for contracts – so they went for the most innovative and technically advanced construction equipment available, a Komatsu Australia case study reports.

That saw them choose Komatsu’s intelligent Machine Control (iMC) dozer and excavator technology when bidding for a large contract to construct tailings storage facilities (TSFs) for a major mining operation in Western Australia.

Currently RHT runs four Komatsu iMC machines: two D65PXi-18 swamp dozers, a D155AXi-8 dozer, and a PC360LCi-11, as well as Komatsu wheel loaders, dump trucks, graders, and other excavators on the one site.

Not only does using iMC technology give RHT significant safety, productivity, efficiency and accuracy advantages in TSF construction, it also provides the company’s mining clients the security and peace of mind that their critical facilities have been built to the highest and most exacting standards.

Today that is essential for any mining operation, following catastrophic failures of tailings dams in South America in the past five years, which have killed many people and caused widespread environmental devastation.

To ensure their integrity and long-term performance, it’s essential that TSFs be constructed following an established process, which involves placing the dam material in 300 mm thick layers; these are then compacted, and the top 100 mm scarified to ensure a strong lock with the subsequent 300 mm layer.

Using Komatsu iMC machines in this application, each 300 mm layer can be placed, quickly and efficiently, within tight tolerances, ready for compaction.

And unlike conventional ‘bolt-on’ machine control systems, the iMC system prevents dozer blades or excavator buckets from ‘over-digging’ into the already compacted and scarified layers, ensuring they are not compromised during placing of the next layer.

When RHT was formed, Riccardo, Heddon and Tyler (the company’s name comes from their surname initials) saw the opportunity to use Komatsu’s iMC technology as a real competitive advantage.

“These days, you’ve really got to innovate,” Heddon says. “Clients want to see that you are innovative and you’re not a dinosaur.

“I’ve been going to shows like CONEXPO and BAUMA for years, and I see all the latest stuff, and I was wondering how good it actually was. Then we spent some time with Dean Jones and Colin Brindle (from Komatsu Perth), to find out what their iMC technology could do.

“We were convinced enough to buy a D65PXi-18 swampy and a PC360LCi-11 excavator, plus a Topcon base station, which were delivered in February 2019, and took them to the site.

“We also put on Fraser Mead, a young surveyor, who’s passionate about technology, plus he’s really into drones and how they can really help with the whole mine infrastructure construction process.”

As of mid-June, Mead and RHT are trialling Komatsu’s EDD (EveryDay Drone) technology, a high precision UAV (drone) survey system providing industry-leading super-fast on-site processing using Komatsu SMARTCONSTRUCTION’s Edge technology.

“Initially the operators weren’t convinced about the iMC machines; they said ‘stuff this, I’m an operator, I don’t need that’, but then after a few days of seeing what the technology could do, they were going ‘wow!’,” Heddon says.

“On the first dam we built, we never put a grader on it, did the whole batter with just our first D65EXi dozer and the PC360LCi excavator. I have never, ever done that before; they are exceptionally good. The dams look great, the batters look great, we’re never having to do rework, we get it right – from the start to the end. It’s always spot on.”

Expanded fleet

Following the success of its first D65PXi-18, RHT bought a second D65PXi-18 in September last year, and the D155AXi-8 in February this year.

“At the moment, we’ve got all these machines working on site, building up to three dams at one time,” Heddon says.

“With the dozers, we are using them for winning material from borrow pits, while the excavator is pulling up batters.”

Building tailings dams for larger mines requires large amounts of earthworks – with dam walls up to 4-6 km around, along with haul roads, so there is a lot of earth to be moved.

RHT’s two smaller iMC machines, with their swamp tracks, are proving ideal for the precision final trim work to millimetre level accuracy, while the larger D155AXi-8 (pictured) is being used for the bulk earthworks on the dams and haul roads, according to Komatsu.

“On the newer dams we are building, we are using clay oxide materials, which are heavier to work with, which is why we brought in the D155AXi,” Heddon says. “Plus, we can also use it for building haul roads. We can just map in a haul road route and design, and the machine can go out and build it, even in rock and clay.”

One thing RHT has found is that the D155AXi-8 has not so far been giving quite the final trim accuracy of the D65PXi-18s.

“Certainly, it is extremely accurate compared with any conventional dozer next to it, but because we have seen how precise the D65s are to a few millimetres, we were expecting that with the D155. However, because it is bigger, it corrects slightly differently,” Heddon says.

“It’s still good, still within coo-ee of what we need, but we know at the moment it’s giving a slightly rougher surface, so you’ve got to take things a bit slower, use a lower gear to get there.

“On the bulk side, Komatsu’s intelligent Machine Control works really well, absolutely on this bigger dozer. You can just set it, and it does exactly what we need. It’s on the fine control, where I think we can get it going even better.

“Because this is all so new, it’s something we are working with Komatsu to perfect.”

Heddon also says iMC ensures that rework and over-excavation never occurs – eliminating overruns and field survey work.

“With Komatsu’s intelligent Machine Control acting as a rover, we know we are always building to the exact specs; we are never over-building, and everything is always exactly level and ready for rolling.

“We don’t require anyone to go out there with a dumpy level checking levels and all that stuff,” he says.

No micro managemenent

The other big advantage is having all the works designs already in the machines, ready for the operators as soon as they need them.

“That’s a big saving because the operators have everything at hand in the machines to do the work,” Heddon says.

“In the old days, we’d have two teams out there pegging the site, one for the day shift, and another for the night shift.

“Now we just put in a couple of reference pegs, then once the operator has the levels, it’s all good to go.”

And, as each part of the job is completed, it can be immediately checked and audited – and the records remain readily available at any time in the future for clients or geotechnical engineers.

“This technology means that the as-built track mapping is all there from the start. When you’re building a tailings dam, it’s essential that layers go down in 300 mm lifts, before the next one goes on top,” he says.

“We can see all this on the computer and know that it was done precisely. So, in future, if there is ever a question with a dam, we can go back in there and show that it was done exactly right. There’s no need for anyone to go in and micromanage. It is a great system.

“The other great thing about these iMC machines is that essentially they act as a mobile rover because everything is done within the machine.

“So, the surveyor can be away on another mine site, and if the operator finishes a job, the surveyor can jump in remotely, and work together with the operator to set things up for the next job. So, people are not sitting around waiting for someone to get back after lunch to start up again.”

Greatly increased site safety is another huge advantage with iMC, according to Komatsu.

“Safety is paramount for us,” Heddon says. “And not having people working on the ground around dump trucks, excavators, wheel loaders, dozers and other machines, is a major safety component. It’s just unreal.”

Heddon has also observed interesting reactions from operators using the iMC systems, and RHT’s clients.

“When these machines first came to site, people said it was just more stuff to go wrong. But then after a few days, they all agree the benefits are countless.

“And our clients have been really impressed with the quality, efficiency and technology the iMC machines offer.

“With this technology, we have the trucks deliver to the site, the dozers push it out – and it’s so level that the trucks can keep working, whereas before we’d have to call in a grader to give the trucks access.

“Everyone is stoked with it, the whole concept. We’ve since bought a second base station, and we’re putting that in our second site.”

The future

Heddon sees tremendous potential for Komatsu’s iMC technology in future projects.

“This is really moving into the future, that’s the only direction we want to go now.

“And particularly after those catastrophic dam failures in Brazil, the more you can prove the quality of your work and show that to the geotechs and the clients, the more successful we can be.

“They really need the confidence that these dams are getting built correctly at all times, not just some of the time.

“It’s giving the mining companies that security and peace of mind that their dams are built right, so they know they have their dams constructed to worlds best practice.

“We’re very committed to this technology. We want to see it on all our earthmoving machines, and we are very keen to see it on the larger excavators, at least up to PC490 size,” Heddon says.

Seequent’s GeoStudio Core to help geotech engineers tackle major engineering challenges

Geoscience software company Seequent has announced the release of GeoStudio Core, a new, completely reformulated SIGMA/W product.

These upgrades allow geotechnical engineers to understand and tackle major engineering challenges for infrastructure and mining projects – from dams and levees to tunnelling and the stability of cuts in underground and open-pit mines, the company says.

Paul Grunau, President of Seequent’s GEOSLOPE, says GeoStudio Core 2021 is the most significant GeoStudio release in the past five years.

“SIGMA/W has been completely redeveloped from the ground up, delivering new levels of confidence and capability for geotechnical engineers needing to assess ground deformations and stability,” Grunau said. “The new strength reduction stability analysis in SIGMA/W complements the industry-trusted solutions in SLOPE/W to provide a rigorous understanding of slope failure mechanisms, allowing the engineer to design effective stabilisation measures. These products integrate with SEEP/W to include the impact of changing groundwater conditions, providing a comprehensive solution for stability problems.

“The combined GeoStudio Core solution runs in a single integrated environment, speeding up the project workflow and easily scaling with the user’s needs. All project data and analyses can be combined into a single project file, enabling smooth data exchange and simpler data management.”

GeoStudio Core, with SIGMA/W’s expanded material model library and new analysis types, allows for comprehensive modelling of a wider range of soil and rock behaviour, according to Seequent. For example, simulating the strain-softening behaviour of brittle clays enables stability control of a tailings dam or roadway cut.

The new GeoStudio multi-physics solver enables SIGMA/W to offer improved solver performance and enhanced modelling of rapid reservoir drawdown, open-pit mine dewatering effects on highwall stability, and solute transport from tailings ponds.

Mining network needs to align on safe tailings dam design, SRK’s Spies says

Safer tailings storage facilities (TSFs) – or tailings dams – can be achieved when mine owners, contractors and engineering consultants work closely together, says SRK Consulting’s Linda Spies.

Speaking after a recent Southern African Institute of Mining and Metallurgy (SAIMM) conference focusing on tailings dams, Spies, Senior Geotechnical Engineer at SRK Consulting, said that mining executives today required more assurance that their tailings dams are safe, with controls becoming much stricter. Greater transparency was also being demanded by other stakeholders such as investors and communities, she added.

“After several hundred lives were lost in two well-publicised tailings dam failures in Brazil, in 2015 and 2019, awareness of tailings dam risks has been raised within the mining industry and in the public eye globally,” she said. “These latest failures were especially significant insofar as senior management at the mining companies were for the first time being implicated directly with charges of manslaughter and environmental damage.”

She noted that while conferences on this topic usually involved mainly tailings dam practitioners and academics, this event had strong representation from owners; contractors, who are responsible for tailings dam construction; and consultants, who design TSFs and monitor their construction.

“This meant that the discussion was more holistic and valuable, enriched with insights from these various perspectives,” she said. “This is vital in promoting innovation, safety and environmental and social responsibility in the design, operation and closure of tailings dams.”

While the tone of the event was serious considering recent failures, there was also an optimism flowing from a showcasing of best practice in the field and how this was being successfully applied. In her own case study presentation on a lined tailings dam at a South African platinum mine (Impala’s Marula dam), Spies highlighted the complexities introduced by the liner requirement – and how good drainage design and quality assurance were an important part of the solution. (see Getting lined tailings storage facilities right below)

Among the key issues discussed at the conference was whether upstream tailings dams should be allowed – as this was one of the commonalities in the recent Brazil failures. High-level input was given in a panel discussion by senior leaders from a mining company, a law firm and an insurance firm, including technical opinions from tailings industry expert and specialist geotechnical engineer Adriaan Meintjes, a Partner and Corporate Consultant from SRK.

According to SRK Principal Hydrogeologist and Numerical Modeller, Sheila Imrie, who also presented at the event, tailings is rightly receiving considerable attention from a combined engineering and scientific perspective and will continue to do so in the future.

“The continued application of the latest technologies by the industry’s top experts is critical,” Imrie said. “Industry must also ensure that sufficiently detailed research, monitoring and numerical modelling informs the future design and current management of tailings dams.”

She presented a paper on ‘3D Seepage Modelling in Tailings Storage Facility Analysis and Design for Low Permeability Lined Basins’ with SRK Civil Engineer, Wesley Rouncivell. A key aspect of the safe operation of tailings dams into the future involves comprehensive and rigorous monitoring of these facilities on a regular and real-time basis, they said.

In another SRK presentation, GIS Specialist, Ansu Louw, and Civil Engineer, Riaan van der Colf, gave their insights on a ‘GIS-enabled, Web-based TSF Monitoring Solution’ by SRK to enhance monitoring of tailings facilities.

Getting lined tailings storage facilities right

The inclusion of a liner in a tailings dam brings many environmental benefits, but also increased complexity in design, construction and operation, Spies says.

In her presentation – ‘Design of an HDPE-lined platinum tailings facility in South Africa’ – at the SAIMM Tailings Storage Conference, in Gauteng, recently, Spies highlighted the importance of well-designed drainage systems. These are vital to drawing down the phreatic surface, reducing the seepage gradient and minimising the liquefaction potential of tailings, she said.

She also emphasised high construction standards to ensure tailings dams successfully limit seepage, and outlined a series of quality control and assurance measures.

‘World-first’ public database of mine tailings dams launched

Environmental organisation GRID-Arendal, with support from the UN Environment Program (UNEP), says it has launched the world’s first publicly accessible global database of mine tailings storage facilities.

The database, the Global Tailings Portal, was built by Norway-based GRID-Arendal as part of the Investor Mining and Tailings Safety Initiative, led by the Church of England Pensions Board and the Swedish National Pension Funds’ Council on Ethics, with support from the UNEP. The initiative is backed by funds with more than US$13 trillion under management, according to GRID-Arendal.

Professor Elaine Baker from the School of Geosciences is Director of the GRID-Arendal office at the University of Sydney. She said: “This portal could save lives. Tailing dams are getting bigger and bigger. Mining companies have found most of the highest-grade ores and are now mining lower-grade ones, which create more waste. With this information, the entire industry can work towards reducing dam failures in the future.”

The release of the Global Tailings Portal coincides with the one-year anniversary of the tailings dam collapse in Brumadinho, Brazil (pictured above – CREDIT:IDF/Flickr), which reportedly killed 270 people. After that event, a group of institutional investors led by the Church of England Pensions Board asked 726 of the world’s largest mining companies to disclose details about their tailings dams. Many of the companies complied, and the information they released has been incorporated into the database, GRID-Arendal said.

The database will allow users to view detailed information on more than 1,900 tailings dams, categorised by location, company, dam type, height, volume and risk, among other factors.

Kristina Thygesen, GRID-Arendal’s Program Leader for Geological Resources and a member of the team that worked on the portal, said: “Most of this information has never before been publicly available.”

When GRID-Arendal began in-depth research on mine tailings dams in 2016, very little data was accessible. In a 2017 report on tailings dams, co-published by GRID and the UN Environment Program, one of the key recommendations was to establish an accessible public-interest database of tailings storage facilities.

“This database brings a new level of transparency to the mining industry, which will benefit regulators, institutional investors, scientific researchers, local communities, the media and the industry itself,” Thygesen said.

GroundProbe extends Americas mine, tailings dam monitoring reach with Santiago centre

GroundProbe has launched a dedicated monitoring centre in Santiago, Chile, to, it says, provide 24/7 real-time radar and laser monitoring services for tailings dams and mines throughout North and South America.

The centre connects remote sites with industry experts in three languages, according to GroundProbe, with the facility monitoring live slope stability data and reacting to alarms to ensure the maximum safety of people and communities.

Crewed by 45 specialised geotechnical engineers, these centre provide 24/7 expertise to over 30 customers globally, GroundProbe says.

GroundProbe, owned by Orica, is a global leader in real-time technologies used to detect instabilities and predict when mine and dam collapses will occur.

From a launch event in Santiago, GroundProbe CEO Brian Gillespie said the new centre marked an important step for GroundProbe’s future growth, especially for South and North America.

“We’ve witnessed a boom in Brazil for continuous, real-time monitoring of tailings dams, with a huge increase in demand for our remote, 24/7 geotechnical expertise,” Gillespie said.

“We saw it as an absolute necessity to bolster our offering and extend our support services from Asia Pacific to the Americas.

“Placing the centre in Santiago and ensuring its tri-lingual capabilities allows us to do just that.”

GroundProbe has, for many years, been providing 24/7 assistance to customers from its Asia-Pacific monitoring centre. The addition of a second location, operating in Spanish, Portuguese and English, sees GroundProbe remain at the forefront of our industry, the company said.

David Noon, COO of GroundProbe, said: “Our Santiago remote monitoring centre is operational from day one, with our teams already monitoring many tailings dams, a massive hydro-electric dam and even a landslide on a national highway in Colombia.

“Not only is it essential to our customers that our team are native Spanish and Portuguese speakers, but having a centre in Latin America shows our level of commitment to the region and to creating jobs in the local communities we serve.”

To mark the launch, GroundProbe and Orica hosted an event with key customers, industry representatives and stakeholders (pictured).

GroundProbe’s monitoring centres are home to its Geotechnical Support Services (GSS) team and dedicated team of geotechnical support engineers.

The second monitoring centre in Santiago will provide the same services to customers, including: GSS-Remote, a 24-hour remote monitoring solution; GSS-Training, a SSR and laser training service; and GSS-Reporting, the company’s customised analysis and reporting service.

Vale’s Vargem Grande iron ore complex slowly coming back to life

Vale says Brazil’s National Mining Agency (Agência Nacional de Mineração – ANM) has authorised the partial resumption of dry processing operations at the Vargem Grande Complex in Minas Gerais.

The Vargem complex is comprised of three operating mines — Capitão do Mato, Tamanduá and Abóboras — and produces a mixture of fines, lump and concentrate products for the seaborne export market and the Vargem Grande pellet plant.

Vale said all operations of the complex were suspended by ANM on February 20, to prevent “occasional triggers” that could affect tailings dam stability as a result of ongoing activities at the complex.

Vargem was one of several operations that were suspended after one of Vale’s tailings dams ruptured at its Córrego do Feijão mine (Paraopeba complex) on January 25, 2019.

The decision will enable the partial resumption of dry processing operations at the complex within 24 hours, totalling about 5 Mt of additional production in 2019, thus increasing the supply of Brazilian Blend Fines, Vale said.

The Brazil-based miner reaffirmed its 2019 iron ore and pellets sales guidance of 307-332 Mt, as per previous announcements.

Twin Metals looks to avoid tailings dam concerns with dry stacking plan

The developer of the Twin Metals project, in the Iron Range region of northeast Minnesota, USA, has announced plans to use dry stacked tailings at the underground copper, nickel, platinum, palladium, gold and silver asset as the company looks to eliminate the perceived risk of a dam leakage or failure.

Twin Metals Minnesota (TMM), a company owned by Antofagasta, said the dry stack method eliminates the storage pond and dam associated with conventional tailings facilities and has been successfully used in four mines in the northern US and Canada with similar climates to Minnesota.

In 2018, an update of the prefeasibility study for Twin Metals outlined a 18,000 t/d ore project, producing an average of 42,000 t/y of copper, plus nickel and platinum group metals as by-products, the equivalent of some 65,000 t/y of copper.

TMM, like many other potential mine developers, said community concerns about copper-nickel mines have focused on fears of tailings dam failure or leaks that could threaten both nearby surface water and groundwater. This comes after several high profile dam failures in North and South America.

If all goes to plan, the company will use the dry stack method to store the leftover rock from its proposed underground mine on a lined ground facility near the plant site. This will allow reclamation of the tailing site to occur in stages, with the site capped or covered with natural vegetation.

Kelly Osborne, Chief Executive Officer of Twin Metals Minnesota, said: “Dry stack tailing storage is the most environmentally friendly tailings management approach for our site. The first key is that there’s no dam, no risk of dam failure. The moisture content of the filtered tailings is reduced to a material that we can compact and manage seasonally.

“Because there’s no risk of a dam failure, dry stack is considered the best available technology for tailings storage and, after a decade of study and consultation with concerned voices in our community, we determined that it will be an effective choice for our project.”

Equally important, TMM said, is the fact that the tailings from the Maturi deposit at Twin Metals will be non-acid-generating.

“The common concern about sulphides points to a basic misconception about our project,” Osborne said. “The geology of the Maturi deposit provides us with confidence that we can mine here safely and sustainably. The rock sandwiching the layer of copper, nickel and platinum group minerals in the deposit is almost completely free of sulphides. When the targeted minerals are removed during the concentration process and shipped to customers, only a minute amount of sulphides will remain in the tailings.”

Extensive testing over the past decade shows that Maturi deposit tailings will be non-acid-generating, the company clarified.

Dry stack tailings storage has been an option under consideration since Twin Metals began mine planning in 2010, the company said. “As technology has continued to advance, and the application of dry stack in cold, wet climates has proven successful at multiple locations, Twin Metals made the decision to move to it as the best available option,” TMM said, adding that The Minnesota Center for Environmental Advocacy hailed the advantages of dry stack tailings in a statement earlier this year.

Osborne concluded: “Dry stack is one of the ways we are making a 21st century mine that will be the most technologically advanced mine in Minnesota’s history and a model of how copper mining can be done safely and sustainably.”

The approach will be outlined in detail in TMM’s Mine Plan of Operation, to be submitted to state and federal regulators in the coming months. Regulatory review, including hearings for public comment, will cover compliance with regulations to protect water and air quality, drinking water, wetlands, endangered species, plant life and cultural resources. While the MPO is being reviewed the company will advance the feasibility study.

After reaffirming Twin Metal’s right to renew its two federal mineral leases, the Department of Interior reinstated the leases to TMM in May 2018. Antofagasta expects these to be renewed during 2019.

Anglo American’s FutureSmart Mining on its way to tangible technology results

“It’s clear that the pressures on us are unsustainable, whether it is around our carbon footprint, water footprint, or physical footprint, and we are always looking for different ways to push us in this future direction where our footprint will be very different.”

Tony O’Neill, Anglo American Technical Director, knows the company he works for is up against it when it comes to retaining its reputation as one of the world’s leading sustainable mining companies.

It’s clear from the company’s 2018 sustainability report – which saw it achieve a best-ever performance in terms of injuries, a cut in energy use and an increase in greenhouse gas emission savings – that Anglo is going down multiple paths to reach its goals. O’Neill, who joined the company almost six years ago, believes Anglo’s FutureSmart Mining™ programme will play a major role in confronting and overcoming many of the issues it (and the industry) is facing.

“If you look at FutureSmart Mining, at its absolute essence, it is about footprint; how do you change the footprint of mining? How do you have a mine that draws no fresh water? Mines without tailings dams? Mines that look very different?” he told IM.

“It’s getting people to believe there is a different way for mining in an industry that has, to this point, been quite traditional. It is not going to happen overnight, but I think we have a genuine vision that is, in my view, quite feasible.”

IM spoke with O’Neill and Donovan Waller, Group Head of Technology Development, this week to get to the bottom of how technology is making Anglo ever more sustainable.

IM: Could you explain how the Anglo operating model facilitates and fosters innovation within the context of FutureSmart Mining?

TO: The Anglo American operating model is the chassis that underpins everything, giving us certainty in the delivery of our work. When you have got that stability – and the lack of variability – in your business outputs, it is much easier to overlay new technologies and processes. When you then see a difference in operating or financial results, you can confirm it is down to what you have implemented, rather than the underlying processes.

I look at it a little bit like a three-legged stool: you have the operating model on one leg, the P101 benchmark-setting on another, and technology and data analytics on the third leg. They all co-exist in this system and work off each other. Without one, the stool falls over.

The operating model has given us a drumbeat of delivery, and we get the licence to innovate because of this drumbeat.

IM: Do you think FutureSmart Mining is starting to be understood and valued by investors?

TO: They’re awake to it now. I think it is still in the early stages of the story, but they can see what we are doing and the ambition behind it. Ultimately, it will result in a different investment profile, or more investors because of it, but I am not sure that it’s translated in full up to now. The recognition has been more around the general results of the company.

With all these technologies coming through – much of them driven by higher levels of data and the ability to interrogate that data – the vision we imagined way out into the future, I think, is a lot more tangible than when we started out four years ago.

IM: Out of all the tailings dam elimination work you are carrying out (around passive resistivity, fibre-optics, micro-seismic monitoring, coarse particle recovery, polymers, and dry stacking), which innovation will have an impact on Anglo’s operations in the next three-to-five years?

TO: All of them. We started out with our tailings programme in 2013; in fact, our group technical standards were re-issued at the beginning of 2014 and they are now one of the main guidelines the ICMM (International Council on Mining and Metals) uses.

Tailings dams have always been at the back end of the mining process and, in a way, the science behind them has never been part of the mainstream operation. Our view, internally for many years, is tailings dams are one of the industry’s greatest risks.

“Our view, internally for many years, is tailings dams are one of the industry’s greatest risks,” Tony O’Neill says

Ultimately our aim is to eliminate tailings dams. Period. Coarse particle flotation – getting that coarser particle size that drains much more freely – is core to that and you can see a development pathway there. For example, with some of these new flotation techniques, we now only need 1% exposure of the mineral for it to be effective. In the past, it was much higher.

When we upgraded the capability of our tailings organisation, it became clear we needed to get a lot more data off these tailings dams. About three years ago, we started putting fibre-optic sensors into the dams. We have since developed, through our exploration arm, passive resistivity seismic monitoring, which basically tells you where your water sits in the dams. And, we’re putting into Quellaveco micro-seismic measuring techniques, which will be more granular again. You can see the day coming really quickly where tailings dams are a real-time data source for mining companies.

We’re also, with our joint venture partner Debswana, building the first polymer plant in Botswana, which could have an impact on dry tailing disposal.

The thing we need to crack – both ourselves and the industry – is how to dry stack at scale. At the moment, that is still a work-in-progress, but it is doable in the long term.

IM: How is the bulk sorter you have operating at El Soldado, which is equipped with a neutron sensor, working? How has it made a difference to recoveries and grades at the operation?

TO: With the bulk sorter, we’re taking packages of tonnes rather than individual rocks to enable us to get both speed and volume. At El Soldado, we are sorting in four tonne packages. You can adapt the sorting profile by the characteristics of the orebody. We’re generally looking to sort tonnages that are less than you would put in a haul truck body or bucket.

If you step right back, in the past, most processing plants wanted to blend to get an average feed. We are going the other way. We want to use the heterogeneity of the orebody to its advantage; the less mixing we can get ahead of these sorting processes, the better it is for recoveries.

Being able to remove an orebody above the cut-off grade alongside waste tonnages and upgrade the latter has led to an effective lift in head grade. It has been enabled by new sensing technology with a particular type of neutron sensor.

What we have seen in early results has surprised us on the upside. We thought we would see a 5% uplift in head grade, but in fact we have seen about 20% – to qualify that, it’s in its early stages.

O’Neill says the bulk sorting trial at El Soldado has seen about a 20% uplift in head grade in its early stages

If you take this to its logical conclusion, you can see the day coming where you would cut the rock – no drilling and blasting – immediately sort the rock behind the machine cutting it and distribute said rock efficiently into its value in use; you don’t have stockpiles, you have plants sensing the material right through and adapting in real time to the change in mineralogy. I think there is another 3-4% increase in recovery in that whole process when we get it right.

Our sweet spot when we created FutureSmart Mining was always the orebody and processing plants, more so than automation (although that is part of the potential mix). That was different to a lot of the other players in the industry. This focus could lead to the development of different types of plants; ones that are flexible, more modular and you can plug and play.

IM: Do you see these type of neutron sensors being applied elsewhere across a mine site?

TO: Yes, through processing plants and conveyors. In fact, we’re preparing for this on conveyors right now.

What we have found with all this new technology is that, when we implement it, quite often another opportunity arrives. They end up playing off each other, and that is the context for the bulk sorting and coarse particle flotation.

IM: How have Anglo’s Open Forums played into these developments?

TO: We have held eight Open Forums on sustainability, processing, mining, exploration (two), future of work, energy and maintenance.

Out of those eight, I think we have got around 10,000 ideas from them. These forums have been specifically designed where only about a third of participants are from the mining industry, with the other two thirds coming from the best and brightest analogous industries we can tap into – automobile, oil & gas, food, construction, even Formula 1 racing and NASA.

The reality is that out of those 10,000 ideas, the success rate is about 1:1,000, but the one that makes it is quite often a game changer.

IM: Going back to the bulk sorters, am I right in thinking you plan to put these into Mogalakwena and Barro Alto too?

TO: The aim is to have them across our business. At El Soldado, the copper angle is very important. The technology – the sensing and using the data – is probably a touch more advanced in copper, but we are building one currently in our PGMs business at Mogalakwena and a bit behind that, but ready to be built, is one in nickel, yes.

In terms of our programme, you will see them spread across our business in the next, hopefully, 18 months.

IM: Where does your approach to advanced process control (APC) fit into the FutureSmart Mining platform?

TO: We want to have APC in some form across all our business by the end of this year. We have probably come from a little behind some of the other players in the industry, but we’re pushing it quite aggressively to give us the platform for data analytics. The upside we have seen just by putting the process control in so far has surprised me a bit – in a good way; power reductions, throughput, having this different level of control. All of it has been pleasing.

We spent about 12 months looking at the whole data analytics space to see how we were going to implement our solution. If you look around at the sector, everyone wants to be involved and profit share. If you add it all up, you could end up with not a lot of profitable pieces at the end. We have strategically chosen the pieces we think are important to us and our profit pool and have been happy to be a little looser on some of the non-core areas.

The other key plank to the APC is that we own the data. The reality is, in the new world, data is like a new orebody and we’re not willing to let go of that.

IM: Your Smart Energy project involving a haul truck powered on hydrogen has certainly caught the attention of the market: how did you come up with this innovation?

TO: Initially, we couldn’t make renewables work from an investment criteria perspective – it was always close, but never quite there. Donovan’s team then took an approach where they said, ‘forget the normal investment criteria. All we want to do is, make the business case wash its face.’ In doing so, it enabled them to oversize a renewable or photovoltaic energy source – the power plant – using that extra power to produce hydrogen and putting that hydrogen to use in the haulage fleet. Re-engineering the haulage fleet gave us the business outcomes we were looking for.

DW: These business cases bring you to temporary barriers. When you hit that temporary barrier, people normally stop, but what we said was, ‘OK, just assume it is not there and go forward.’ That brought the whole business case back again by looking at it differently again.

Anglo’s Smart Energy project is aiming to power a 300-t class truck with hydrogen fuel

IM: Where is this project likely to be situated within the group?

TO: We’re still not 100% fixed as the initial work will be done here (the UK). You are talking about quite specialist skills working with hydrogen.

When the system has gone past its initial testing, it will go to a site, probably in South Africa, but we are not 100% locked into that at this point.

IM: On the 12-month timeline you have given, when would you have to be on site?

TO: The infrastructure will be pre-built here in the UK. We’re effectively testing it here. In a way, the physical truck is the easy bit.

It’s going to be using a 300-t class truck. The guys have already done quite a bit of the detailed measuring and the design elements are well under way.

We’ve also taken the approach to use pre-approved technology, which Donovan can talk about.

DW: This minimises the risk on the first go and allows us to, later, tailor it. For example, if you don’t have a right sized fuel cell currently available off-the-shelf, you just use multiple standard-size fuel cells for now. Then, when you get into the final version you could tailor them into something more specific.

IM: On mechanised cutting, you recently mentioned the building of a “production-sized machine” for at least one of your mines in South Africa. Is this a variant of the Epiroc machine – the Rapid Mine Development System – you have been using at Twickenham?

TO: It’s the next generation of machines. It’s fair to say that, in the last 12 months, the technology has come to the point where we are confident it is viable.

What we’re looking for is a fundamental breakthrough where, for example, we can take the development rates up three or four times from what you would usually expect. That is what we’re chasing. It would involve some sort of pre-conditioning of the rock ahead of the cutting, but the cutting, itself, works.

For us, mechanised cutting is a real solution to some of the safety issues we have had on our plate. Regardless of whether it goes into South Africa or another underground mine, we see it as a key part of our future underground design and operation.

IM: What type of rock pre-conditioning is this likely to be?

TO: I think around the world, people are looking at electricity, microwave, laser, a whole suite of things. None of them have yet quite landed, but they all have potential.

IM: Where does haul truck automation fit into the pipeline for Anglo American?

TO: All the equipment we buy, going forward, will be autonomous-capable, which means we can run it in either format (manned or unmanned). You are then left with a number of decisions – have you got the design to retrofit automation? Is there a safety issue to be considered? Is there a weather issue to contend with? There are a whole series of gates that we’ll take it (automation projects) through.

It’s good to go back to P101 here. Where P100 is getting all of our key processes to world-class benchmarks, P101 is about establishing a new benchmark. By definition, if you get your operations to that point, the gap between that manned performance and autonomous performance is not that great.

Autonomy is part of our future armoury, but when and where and how, we’ll have to wait and see. For example, we are currently looking at the option of autonomous haulage trucks at one of our open-cut mines in Queensland.

When you look at our portfolio of operations, it’s often a more complex environment than when you are just working in the wide open Pilbara.

BHP establishes task force to handle tailings dams

BHP says it is establishing a dedicated Tailings Task Force to drive enhanced focus on internal dam management plus support the development of international best practice.

The announcement came during an environmental, social and governance briefing where the company also revealed it is “progressing the investigation of new technologies to further mitigate current dam risks and eliminate future risk”.

BHP has interests in 67 operated tailings facilities across all its sites. Of these, 13 operated facilities are active, (12 in Australia, one in Chile), 29 are operated upstream facilities (five of which are active). In addition, its non-operated joint ventures have nine facilities, five of which are upstream, of which all are inactive.

Back in 2016, the company carried out a Dam Risk Review, which identified no immediate concerns regarding dam integrity. This was undertaken to assess the management of tailings facilities following the failure of the Fundão dam at Samarco (a joint venture with Vale).

BHP has since undertaken Dam Safety Reviews which provide assurance statements on dam integrity, the company said.

The company said on the appointment of the task force: “Prior to Brumadinho we already had a significant focus on looking at how we could deliver a step change reduction in tailingsrisk. Brumadinho however has further strengthened our resolve.”

The new Tailings Task Force will be accountable for further enhancing the company’s focus on tailings including the continued improvement and assurance for BHP’s operated tailings storage facilities, the company said. It will also progress its technology efforts and ongoing participation in the setting of new international tailings management standards.

On the latter, BHP said it continued to work with the International Council on Mining and Metals its peers to “drive a step change in tailings management across the sector”.

Vale exploring dry stacking/magnetic separation to eradicate tailings dams

Vale has confirmed a Reuters news report from last week stating that it would spend an additional BRL11 billion ($2.5 billion) on dry iron ore processing over the next five years.

The company said it has invested nearly BRL66 billion installing and expanding the use of dry processing, using natural moisture, in iron ore production in its operations in Brazil over the last 10 years and it would carry on this trend.

“By not using water in the process, no tailings are generated and, therefore, there is no need for dams,” the company said, added that about 60% of Vale’s production today is dry, and the goal is to reach 70% in the next five years.

Dry processing is used in the mines of Carajás, Serra Leste and the S11D Eliezer Batista Complex (pictured), in Pará, Brazil, and in several plants in Minas Gerais. In Pará, in the Northern System, about 80%, of the almost 200 Mt produced in 2018 was through dry processing. The main Carajás plant, Plant 1, is in the process of conversion to natural moisture: of the 17 plant processing lines, 11 are already dry and the remaining six wet lines will be converted by 2022.

Serra Leste’s treatment plants, in Curionópolis, and S11D, in Canaã dos Carajás, also do not use water in ore treatment, according to Vale. In S11D, for example, the use dry processing, using natural humidity, reduces water consumption by 93% when compared to conventional iron ore production.

In Minas Gerais, dry processing increased from 20%, in 2016, to 32%, in 2018. Today, this type of processing is present in several units, such as Brucutu, Alegria, Fábrica Nova, Fazendão, Abóboras, Mutuca, Pica and Fábrica. “Over the following years, the objective is to roll it out at other locations in Minas Gerais, such as the Apolo and Capanema projects, which are currently under environmental licensing,” the company said.

Vale said: “Dry processing is linked to the quality of the iron ore extracted from mining. In Carajás, as the iron content is already high (above 64% Fe), the ore is only crushed and sieved, so it can be classified by size (granulometry).

“In Minas Gerais, the average content is 40% iron, contained in rocks known as itabirites. To increase the content, the ore is concentrated by means of wet processing (with water). The tailings, composed basically of silica, are deposited with water in the dams. The high-grade ore resulting from the process can then be transformed into pellets at the pelletising plants, increasing the added value of the product.”

The mills that operate dry processing in Minas Gerais depend on the availability of ore with higher levels – about 60% Fe – still found in some mines in the state. “In order to achieve the necessary quality, and be incorporated into Vale’s product portfolio, it is necessary to blend with Carajás ores, carried out at Vale’s distribution centres in China and Malaysia. The process allows Vale to offer excellent quality ore which can be tailored to meet the needs of our clients,” the company said.

The blending of the product with natural moisture does not eliminate the need for humid concentration of the low-grade itabirite used in the production of pellets. However, to reduce the use of dams, Vale plans to invest approximately BRL 1.5 billion on dry stacking technology in Minas Gerais between 2020 and 2023. This technique filters and reuses waste water and allows the latter to be stored in piles, thus reducing the use of dams. The goal is to achieve up to 70% of the waste disposed in the coming years, but success depends on the improvement of technology and external issues, such as environmental licences, Vale said.

“Today, Vale doesn’t have a dry stacking operation that can deal with the production quantity especially in a region with high rainfall indices, such as the Ferriferous four-side, in Minas Gerais. The available dry stacking technology is used on a small scale around the world – up to 10,000 t/d of tailings produced – in desert regions or with low rainfall. In Minas Gerais, Vale’s tailings production quantity is, on average, 50,000 t/d per unit,” Vale said. In 2011, the company developed a pilot project on the Cianita stack in Vargem Grande, after an investment of BRL100 million.

The studies were completed in 2018 and the technicians evaluated the geotechnical behaviour of piles under rainy conditions. The next tests will be applied on an industrial scale at the Pico mine in the municipality of Itabirito, Vale said.

“Another solution that has been studied is the dry magnetic concentration of iron ore based on the innovative technology developed by New Steel, a company acquired by Vale at the end of 2018 for BRL1.9 billion,” Vale said. “The dry magnetic concentration eliminates the use of water in the concentration process of the low-grade ore, which disposes the waste generated in sterile piles, similar to what happens in dry stacking. This technology, however, is in the industrial development stage and is not yet ready to be applied on a large scale.”