Tag Archives: SAG mill

Metso Outotec set for SAG mill Premier at Northern Star’s Thunderbox

Metso Outotec says it will deliver a high-capacity, high-powered Premier™ SAG mill to Northern Star Resources Limited’s Thunderbox gold mine expansion project in Western Australia.

The typical value of such a delivery is approximately €15 million ($17.7 million) depending on the final scope, according to the OEM. The order has been booked in the company’s Minerals’ first half of 2021 orders received.

On award of Northern Star Resources’ largest mill to date, Northern Star’s General Manager Processing, Simon Tyrrell, said: “The Thunderbox expansion increases the operation’s hard-rock processing capacity to 6 Mt per annum from the current 3 Mt/a, and decreases processing costs as outlined in our 2021 Investor Day Presentation.

“Northern Star’s selection of Metso Outotec for the mill supply is supported by their locally-based expertise, large mill supply history and ongoing collaboration with Northern Star.”

Earlier this month, GR Engineering Services executed an engineering, procurement and construction contract with Northern Star Resources in relation to the expansion project.

Christoph Hoetzel, Head of Grinding Business Line at Metso Outotec, said: “We are pleased to be chosen as a supplier for the Thunderbox expansion. The gear-driven Premier SAG mill to be delivered will feature 18 MW of motor power.

“With the Premier mill range, we advance our unrivaled innovation legacy providing our customers with most reliable technology, engineered to exceed their specific requirements. We are looking forward to continue the collaboration with Northern Star Resources and to be part of their success story.”

The Premier horizontal grinding mills are customisable solutions built on state-of-the-art grinding mill technology, process expertise and design capability, the company says. The Premier horizontal grinding mills are engineered to “excel and create vast possibilities” for customers and applications.

These mills can be integrated with Metso Outotec mill reline equipment and are supported by the company’s extensive services network to ensure optimisation during the mills’ lifetime, the company says.

Condor Gold looks to GRES’ Hanlon for SAG mill advice at La India

Condor Gold says it has selected Hanlon Engineering & Associates to develop a feasibility study level design for a new processing plant built around its recently acquired SAG mill at the La India gold project in Nicaragua.

A wholly owned subsidiary company of GR Engineering Services Limited (GRES), Hanlon is based in Tucson, Arizona. As lead engineer for this study, Hanlon will be responsible for the engineering designs, the capital cost and operating costs of the processing plant to a FS level of design.

Condor, earlier this year, entered into an agreement to purchase a completely new Metso Outotec SAG mill package from First Majestic Silver to serve La India.

The feasibility study design will develop costs to a +/- 15% level of accuracy for the design, capital expenditure and operating expenditure of a fully engineered processing plant package, which is normally a mandatory requirement of debt financing. The processing plant will be designed to a nominal capacity of 2,300 t/d, but have the built-in capacity in several key areas to potentially upgrade throughput to 2,850 t/d. At the 2,300 t/d rate, initial production is expected to be 80,000-100,000 oz/y of gold.

Hanlon is due to deliver the FS level engineering designs for a new processing plant within 12 weeks, working in conjunction with its GRES and using their extensive global experience with the design, construction and expansion of gold processing plants.

Mark Child, Chairman and CEO, said Hanlon Engineering was previously engaged by First Majestic Silver, the vendor of the SAG mill, to help design the new SAG mill recently purchased by Condor.

“Their knowledge of the SAG mill and involvement with many similar process plant designs completed to date will help fast track the delivery of the feasibility study design,” he said.

The Axora take on crushing and comminution

As we are continually told, comminution is one of the most energy intensive single steps in the resource extraction business.

One estimate is that it accounts for 36% of all the energy used in the extraction of copper and gold, which is only a shade over the 30% proposed as an average by another industry expert for all mining and mineral processing industries.

It also accounts for an estimated 3% of the global energy requirement for metal production.

These energy requirements are shocking from a sustainability and greenhouse gas emission perspective; they are also extremely costly regarding operating expenses on site.

It is with this in mind that IM touched base with Joe Carr, Industry Innovation Director of Mining at Axora.

A spinoff from the Boston Consulting Group, Axora has emerged as a business-to-business digital solutions marketplace and community for industrial innovators. It says it allows industrial companies to discover, buy and sell digital innovations and share knowledge in its community, powered by an advanced marketplace.

“We exist to transform industries to be digital, safer, more sustainable and efficient,” the company states on its website.

Having recently gone to press with the annual crushing and comminution feature (to be published in the IM April 2021 issue), IM spoke with Carr to find out what the Axora marketplace has to offer on the comminution and crushing front.

IM: What are the main issues/concerns you continuously hear from your mining clients when it comes to designing and maintaining comminution circuits? How many of these problems/issues can already be solved with existing technology/solutions?

JC: One of key issues in this area we hear from our customers at Axora is the blending quality of the input ores.

Joe Carr, Industry Innovation Director of Mining at Axora

This could be particularly relevant in the sulphide space, for instance.

I did some work years ago on Pueblo Viejo for Barrick. When I was there, one of the things we were working on was blending the sulphides as we were feeding the mill from numerous satellite pits with very different sulphide grades. Because we were processing the ore with an autoclave, high-grade sulphides would cause a temperature spike and the low-grade sulphides would lower the temperature. This constant yo-yoing of the feed into the autoclave was terrible for the recovery of metals against the plan.

Generally, the old school way of blending is setting up stockpiles of ore based on whatever variable you want to manage at your operation. You would put a defined amount of each into the primary crusher on the understanding this would create a ‘blended’ feed for the processing plant.

With the information we have at our fingertips today, this process seems outdated.

You could, for example, use HoloLens or another VR system in tandem with the shovel operator to be able to see exactly what material he or she is excavating. That can then be linked back to the geological block model, with this material then tracked in the trucks and onto the run of mine stockpile, before heading to the plant.

This is where something like Machine Max comes in. Machine Max is a bolt-on IoT sensor that tracks where your trucks are in real time – where they have been and where they are going. The processing piece requires block model integration into a mine plan system. If you have the building blocks in place – the networking, sensors, additional infrastructure, etc – Machine Max could, when integrated with this model, allow you to attempt real-time ore tracking.

“If you have the building blocks in place…Machine Max could, when integrated with this geological block model, allow you to attempt real-time ore tracking,” Joe Carr says

The issue is not that the technology doesn’t exist, but that the mining industry hasn’t yet cracked putting all of this together at an industry-wide scale, available to all miners.

You can carry out a project like this or go totally the other way and have a machine-learning or artificial intelligence algorithm in the plant that is constantly reading the incoming feed. These could be based around the block model inputs, or a digital XRF solution, which is able to constantly tweak or adjust the plant settings to the feed specifications. Process plants are generally setup to handle one type of feed. This is usually only tweaked in retrospect or for short periods of time when the mine plan moves into a different mining horizon.

We also have a comminution solution that understands the feed coming in and optimises the mill and power settings to get the optimal grind for flotation, maximising recovery at the back end. While the input is typically set up to be grind quality and hardness for optimal flotation, there is no reason why you couldn’t configure it for, say, sulphides going into an autoclave, tweaking the autoclave heat settings dependent on the feed.

Once that system is set up, it becomes a self-learning algorithm.

Saving operational costs is another pain point for mining companies we always hear about.

We have a solution on our marketplace from Opex Group, which is looking to optimise production while reducing power. Coming from the oil & gas space, this AI algorithm, X-PAS™, offers the operator an opportunity to adjust the settings while still achieving the same required outputs. This is tied to CO2 reduction, as well as power cost reductions.

Opex Group’s AI algorithm, X-PAS, offers the operator an opportunity to adjust the plant settings while still achieving the same required outputs

In mining, the plant is your largest drawer of power, hands down. Generally, if it is not powered on the grid, it is powered by diesel. Opex Group’s solution can save up to 10% of power, which is a significant amount of fuel and CO2.

The solution reads information from your pumps and motors, analyses the planned output of your plant using all the sensor feeds, and tweaks the variables while sustaining the required output. The algorithm slowly learns how you can change configurations to reduce power, while sustaining throughput. This results in lower power costs, without impacting the output.

Importantly, instead of automating the process, it offers the saving to the operator sat in the control room. Operators, in general, are incredibly reluctant to pass over control to an AI algorithm, but when faced with such power saving opportunities, they will often elect to accept such a change.

And, of course, plant maintenance is always on the agenda.

This is where Senseye, which has been used in the car industry by Nissan and the aluminium sector by Alcoa, is useful.

Essentially, this provides predictive maintenance analytics. It is also a no-risk solution with Senseye backed by an insurance guarantee. It is sold on the basis that if you do not earn your money back within the first 12 months, you get an insurance-backed refund.

There could also be openings in the plant for Razor Labs’ predictive maintenance solution, which is currently increasing the uptime of stackers, reclaimers and car dumpers for iron ore miners in the Pilbara.

IM: When it comes to future comminution equipment design, do you expect digitalisation, wear liner innovations, or equipment design to have more of a bearing on operational improvements at mine sites? Phrased another way; is more emphasis being given to refining and extending the life of existing products with digital technologies and wear solutions, than the design of brand-new equipment?

JC: We believe there is always going to be a focus on retrofit and extensions. Once a mill is built, changing the equipment, upgrading, etc is very hard and time consuming. The logistics of getting a new SAG mill to site, for example, are mind boggling. New technology will always come for new sites, but most of the world’s mining capacity is already in place. I would expect most digitalisation to focus on two areas:

  1. Getting more and longer life from all the assets. For example, extending liner life, reducing operating costs and shortening downtime between refits; and
  2. Drawing insights from the existing asset with a view to sweating it. No mill ever stays at nameplate; there is always an increase in production. One or two percent more throughput can put millions onto the bottom line of a company. No mill wants to be a bottleneck in the cycle. In a mine there are always two goals: the mine wants to produce as much ore as possible to put the pressure on the mill, and the mill wants to run as fast as possible to put pressure on the mine.

When it comes to extending liner life, we have a solution worth looking at.

One of the companies we work with out of Australia has an IIoT sensor all tied to wear and liner plates. It is a sensor that is embedded into a wear plate and wears at the same time as the wear plate itself wears. It provides this feedback in real time.

So, instead of the standard routine changeout, it gives you real-time knowledge of what it is happening to these wear parts.

We have a great case study from Glencore where they installed the sensors for around A$200,000 ($152,220) and it saved several million dollars. The payback period was just weeks.

Where I want to take it to the next level is pairing the wear plate monitoring technology on chutes and ore bins and looking into SAG mills and crushers. Relining your SAG mill or primary gyratory crusher is a massive job, which takes a lot of time and cuts your productivity and output by a huge amount. Wear plates are made as consumables, so if you can use 5% less over the space of a year, for instance, there are huge cost and sustainability benefits. You can also more accurately schedule in maintenance, as opposed to reacting to problems or sticking to a set routine.

IM: When compared with the rest of the mine site, how well ‘connected’ is the comminution line? For instance, are gyratory crushers regularly receiving particle size distribution info for the material about to be fed into it so they can ‘tailor’ their operations to the properties of the incoming feed?

JC: Generally, not really. The newer, better financed operations tend to have this. Taking the example above, when designing a plant flowsheet, the close side settings are used. But are they updated on the fly to optimise the plant? Not really. Most processes are designed with a set number of conditions to operate at their maximum.

Most plants dislike, and are not set up to handle, variation in their system, according to Carr

Most plants dislike, and are not set up to handle, variation in their system. They like consistent feed quality and grade to achieve maximum recoveries. Over the next few years, the companies that develop the best machine learning or AI models to run plants in a more real time, reactive way will see the biggest growth. A mill will always say it’s the mine that needs to be consistent, but the nature of geology means that you can never rely on this. As one geologist I knew said, “geology, she is a fickle mistress”.

IM: Where within the comminution section of the process flowsheet do you see most opportunity to achieve mining company sustainability and emission goals related to energy reductions, water use and emissions?

JC: In terms of emissions, at Axora we are actively looking at technology that can help across the entire plant. There was a great paper published in 2016 around this specific topic ‘Energy Consumption in Mining Comminution’ (J Jeswiet & A Szekeres). The authors found that the average mine used 21 kWh per tonne of ore processed. Given diesel produces 270 g per kWh, this means a plant produces 5.6 kg of CO2 per tonne of ore processed, on average. For a 90,000 t/day site, this might represent 510 t of CO2 per day (186,000 t/y), just for processing. To put that into context, you would need 9.3 million trees to offset that level of carbon.

If the industry is serious about lowering its carbon footprint, especially Scope 1 and 2 emissions, then the focus has to come into the process. There are easy wins available from proven solutions in other sectors for companies that want to take them.

Roxgold lays Séguéla groundwork with Metso Outotec, Lycopodium contract awards

Roxgold says it has awarded a SAG mill order for the Séguéla gold project in Côte d’Ivoire to Metso Outotec as part of its efforts to advance the project through to construction in the coming months.

The move comes ahead of the release of feasibility study on the project next month, which will build on a 2020 preliminary economic assessment (PEA) that outlined an operation capable of delivering over 100,000 oz/y of gold over eight years at average all-in sustaining costs of $749/oz. This study also incorporated a single stage primary crush/SAG milling comminution circuit with 1.25 Mt/y throughput.

At the same time as selecting Metso Outotec for the SAG mill contract, Roxgold has awarded preferred contractor status to Lycopodium Minerals Pty Ltd and is currently negotiating the engineering, procurement, and construction (EPC) agreement with the company for the 1.25 Mt/y carbon-in-leach processing facility and other supporting infrastructure to be constructed at Séguéla.

The fixed price agreement increases confidence in the total capital cost for the project, as it is by far the largest scope at Séguéla, Roxgold said.

“With this agreement in the final stages of negotiation and several other key scopes now tendered and priced, approximately 65% of the pre-production capital estimate has now been fixed or finalised,” the company added. “This level of detail provides increased confidence around the pre-production capital estimate, which is expected to be in-line with the previous estimate of $142 million, as outlined in the PEA.”

In terms of progressing work on long-lead time items, Roxgold said it had awarded the plant site bulk earthworks tender, with a contract expected to be executed and works commenced in the June quarter to support the project critical path.

The company has continued to advance its early works program at site including upgrading of the site access road and construction of the accommodation village. Contracts were awarded for camp bulk earthworks and camp construction, with first concrete poured last month, it said.

Surveying has been completed for the 33 kV and 90 kV power lines to tie into the existing 90 kV transmission line running across the property, which is connected to the 225 kV ring main system around the country. These early work activities will enable a rapid ramp up to full construction upon completion of the feasibility study and mine financing in the June quarter of this year.

Roxgold says it has undertaken a competitive tender process and has conducted a detailed assessment of the contract mining proposals received. It is currently completing diligence on the shortlisted parties and plans to award the mining contract later this year to allow for contractor mobilisation, site establishment,and commencement of pre-production mining early next year.

John Dorward, President and Chief Executive Officer, said: “The Séguéla project has rapidly become a cornerstone asset for Roxgold, and we believe that the project will provide significant value to all our stakeholders.

“The feasibility study is on track to be announced in the second (June) quarter, which we believe will demonstrate the ongoing evolution of the Séguéla PEA with an enhanced mine life and project economics with the inclusion of the high-grade Koula deposit into the mine plan.”

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

Condor Gold accelerates La India development with Metso Outotec SAG mill acquisition

Condor Gold has entered into an agreement to purchase a completely new Metso Outotec SAG mill package from First Majestic Silver to serve its La India project in Nicaragua.

The purchase consideration is around $6.5 million – made up of cash and shares – with the SAG mill representing a key item of the plant required to bring La India into production, Condor said.

The SAG mill is estimated by Metso Outotec’s technical support group to have a 2,300 t/d (800,000 t/y) throughput on a sustained basis, based on the metallurgical characteristics of the ore and mineralised material at La India. Based on internal technical studies and mining dilution studies conducted by SRK Consulting, initial production at La India is expected to be 80,000-100,000 oz/y of gold.

Condor says the SAG mill and parts are 90% ready to be shipped. The 2,300 t/d capacity forms “Stage 1 of production”, with capacity to be expanded materially after two to three years of production. Its delivery reduces the order time of this key long lead item by 12 months, fast tracking La India project into production. Condor said there is the possibility of increasing throughput by 22% to 2,850 t/d by installing a 4,100 kW motor (currently a 3,330 kW motor).

Mark Child, Chairman and CEO, said: “The key message is Condor has purchased and sized the mill at 2,300 t/d, significantly shortened the mill delivery time, set a trajectory for detailed project design and an accelerated path to production. What’s more, Condor has acquired a state-of-the-art, complete new SAG mill package with warrantees, manufactured and supplied by Metso Outotec, the premier manufacturer of grinding mills and entire grinding systems for the global mining industry.”

Condor plans to commence gold production at La India in 24 months.

The SAG mill agreement has come about as First Majestic ordered a complete new SAG mill package, which, Condor says, is now superfluous to its requirements.

The SAG mill has a mill diameter of 24 ft (7.3 m) and an effective grinding length of 18.5 ft and a structural charge mass of 315 t, Condor Gold said. The structural design ball charge is 11% with a structural design load volume of 35%. Specific gravity of the material is 2.55. The structural steel liner mass is 240 t; however, with the use of lighter composite liners, the weight and corresponding power requirement can be reduced significantly to 120 t.

The complete SAG mill package manufactured and supplied by Metso Outotec includes:

  • Mill shell fabricated in 8 x 90° segments;
  • Mill heads cast in 4 x 90° segments with demountable trunnions;
  • Ductile ring gear and carbonized pinion shaft;
  • Pinion shaft assembly equipment;
  • Erection cradles;
  • Bracket, coupling and guard;
  • Pinion bearings-2-pad polymer hydrostatic bearings;
  • Transformer for the mill;
  • Gear unit, steel guard and fasteners;
  • Allen Bradley variable speed drive;
  • Allen Bradley PLC mill local panel;
  • 3,300 kW WEG SCIM (motor);
  • Bearing housing;
  • Torque limiter and hubs;
  • Complete feed assembly. ‘Rock box’ feed chute with replaceable steel wear liners;
  • Complete discharge assembly. Fabricated discharge cone (no trommel screen) with replaceable rubber wear liners;
  • Discharge trunnion liner with replaceable rubber wear liners;
  • Installation materials and some spares;
  • Trunnion bearing;
  • Hydraulic torque wrench kit;
  • Liner handler; and
  • Howard Marten lubrication systems (trunnion oil lube, reducer/pinion oil lube, gear spray grease lube).

It is assumed that a pebble crusher will be used in the comminution circuit to provide some additional grinding power and to manage critical size fraction material, Condor said. The SAG mill is equipped with a variable speed drive to allow the mill to operate between 1,500 t/d and 2,300 t/d. Furthermore, it is possible to increase the daily throughput by increasing the motor size, as previously indicated. The 22% boost in throughput could potentially allow gold production to increase by a similar amount, the company said.

The SRK 2017 Technical Report on La India outlined an overall process flowsheet based on a single stage SAG comminution and conventional carbon-in-leach circuit.

Metso Outotec to supply SAG mill to Jervois Mining’s ICO operations

Jervois Mining has appointed Metso Outotec to undertake engineering and fabrication of a SAG mill for its Idaho Cobalt Operations (ICO) in Idaho, USA, which remains on track for first production from mid-2022.

Jervois awarded a contract for the design, fabrication and delivery of a 4.7-m-diameter and 2.5-m-long 750 kW SAG mill. The mill design will comfortably accommodate the nameplate 1,200 short tons/d (1,089 t/d) of ore Jervois applied in its recent ICO bankable feasibility study, the company said, adding that the mill will be delivered to site prior to end of 2021.

As part of the order, Metso Outotec will provide mill layout drawings to Jervois’s appointed engineering firm at ICO, M3 Engineering, so final site layout for upcoming site construction reactivation can be detailed and awarded in the June quarter of this year.

Jervois says it is working through a detailed design phase of ICO and will continue to award long-lead item packages in the coming weeks to schedule delivery to site of all major equipment by the end of 2021. This will enable it to meet construction schedule requirements and targeted commercial commissioning of mid-2022.

Metso Outotec to help modernise Nornickel’s Talnakh processing plant

Metso Outotec says it has signed an agreement to deliver its “industry-leading comminution equipment” to Norilsk Nickel’s refurbishment project at the Talnakh processing plant in Norilsk, Russia.

The contract includes delivery of one SAG mill and two ball mills with a total installed power of 36 MW, as well as two HP series pebble crushers. Metso Outotec will also supply spare parts and consumables, including metallic mill liners, and will supervise the installation of the equipment. The delivery is scheduled for 2022.

While the order value was not disclosed, Metso Outotec said the order has been booked in its December quarter 2020 orders received.

Sergey Dubovitsky, Senior Vice President, Strategy, Strategic Projects, Logistics & Procurement at Norilsk Nickel, said: “The modernisation of the Talnakh processing plant is one of the priority projects for Norilsk Nickel. Its implementation will significantly increase the volume and efficiency of production. To achieve this, we utilise the most modern technologies from Metso Outotec.”

Stephan Kirsch, President, Minerals business area, Metso Outotec, added: “We are pleased to continue our partnership with Norilsk Nickel. The supply of leading-edge equipment from Metso Outotec for the reconstruction of the comminution section at the Talnakh concentrator will enable an increase in the amount of ore processed. Our company has taken part in several projects with Norilsk Nickel to boost throughput rates of the processing facilities, and we are grateful for having been again selected to provide reliable solutions for a project as significant as Talnakh.”

DRA under budget and ahead of schedule at NST’s Jundee expansion project

DRA Global says it has completed its engineering, procurement and construction management (EPCM) contract under budget and ahead of time for Northern Star Resources at the Jundee gold mine, near Wiluna, Western Australia.

The Jundee mining operation is situated in the Northern Yandal Greenstone Belt, with the mine yielding a record 300,000 oz for Northern Star in the year ending June 30, 2020.

Jundee’s processing circuit comprises a two-stage crushing circuit, SAG and ball mill, and conventional carbon-in-leach plant. The ball mill upgrade, undertaken by DRA, increased processing plant capacity to a nominal design throughput rate of 2.7 Mt/y, from 2.2 Mt/y.

DRA delivered the EPCM project scope under budget and ahead of time, with ore commissioning achieved some six weeks ahead of schedule in a total duration of 35 weeks, it said.

“DRA’s project team achieved this outcome by working in close collaboration with the Northern Star project and operations team, the equipment vendors and construction sub-contractors,” it said.

Delivery of the project required overcoming challenges presented by the COVID-19 pandemic, including risk mitigation strategies being initiated to maintain the accelerated project schedule, according to the company.

Northern Star’s General Manager Processing, Simon Tyrrell, said DRA had consistently met and exceeded performance expectations through a collaborative approach to the Jundee ball mill project delivery.

DRA was engaged on the EPCM contract after having completed an engineering and cost study which included scope definition, design, planning, capital and operating cost estimation. The project follows several previous plant upgrades and studies successfully completed by DRA at the Jundee gold mine, which have contributed towards the continuous production growth seen at the mine over the last four-to-five years, DRA said.

The process plant shutdown and tie-in of the new ball mill was performed in conjunction with the Northern Star operations team and contractors without incident, and the process plant has since ramped up to run consistently above nameplate design capacity, the company added.

MACA receives early call up for Red 5’s King of the Hills gold project

Red 5 Ltd says it has taken another key step towards the development of its King of the Hills (KOTH) project in Western Australia, after issuing a notice of award for the engineering, procurement and construction (EPC) contract and the bulk earthworks for the process plant to MACA Interquip.

The EPC contract and bulk earthworks – which encompass the KOTH processing facility, equipping of the bore fields, high voltage power distribution, workshop, warehouse and bulk earthworks – will be undertaken as a fixed‐price contract, Red 5 said.

The KOTH feasibility study outlined a 16-year life of mine plan from open-pit and underground mining, whereby the company would produce 176,000 oz/y of gold over the first six years. The capital cost came in at A$226 million ($158 million) and life of mine all-in sustaining costs were A$1,415/oz.

MACA Interquip, a multi‐disciplined mineral processing provider, has a strong track record of the construction of similar carbon‐in‐leach processing plants to the 4 Mt/y process plant planned at KOTH, Red 5 explained.

Following execution of the EPC contract, commitments to‐date for the KOTH project will total A$143 million, compared with the capital budget of A$155 million for these items – which represent 82% of the total capital budget for processing infrastructure of A$188 million (excluding owners costs and contingency).

Commitments made to date include:

  • Purchase of 240‐bed camp accommodation, water and waste water treatment plants and central facilities;
  • Design and construction contract for a 450‐person village;
  • 6 Mt/y gyratory crusher and 4 Mt/y SAG mill;
  • Early works agreement with APA Group for the gas pipeline lateral; and
  • EPC contract for the process facility and bulk earthworks.

Construction of the village commenced in October 2020 and is on track to be operational in February 2021. The process plant bulk earthworks (for which equipment will be mobilised) are scheduled to commence on December 1, 2020, pending the final remaining permit (currently on schedule).

The EPC contract provides for two phases. The first is limited to A$50 million and Phase 2 is for the remainder of the contract value, which will be released at the discretion of Red 5, based on the status of debt financing.

The notice of award provides for the immediate commencement of the design and procurement activities for the process plant as well as mobilisation of earthmoving equipment to site, Red 5 said. It, however, limits commitments to A$10 million and is an interim measure to allow the plant design and mobilisation for earthworks to commence immediately while the contract is executed.

Once executed, the value of these contracts, together with the purchase of the 6 Mt/y gyratory crusher and 4 Mt/y SAG mill (already awarded to MACA Interquip), is A$129 million.

The purchased long‐lead items of the crusher and mill are currently being transported, in preparation for the planned delivery to Australia late in the June quarter of 2021.

The company is currently calling tenders for both the open pit and underground mining contracts, the independent power producer contract and the supply of gas. These contracts are expected to be finalised in the coming months, it said.

Red 5 Managing Director, Mark Williams, said: “Our decision to award these key contracts and make commitments to significant long‐lead items prior to completing project debt funding reflects our confidence in the robustness of the King of the Hills project.

“Importantly, the commitments made to date are below budget for this stage of the KOTH project, and should give our stakeholders confidence that we are well on track to progress the development of this major project, with production planned to start in June quarter of 2022.”