Tag Archives: Screening

Kwatani large vibrating screen customisation pays off

Process plant designers often underestimate the movement of large vibrating screens when these machines start and stop, a challenge for which Kwatani says it has found an innovative and cost effective solution.

According to Kwatani’s Chief Operating Officer, Kenny Mayhew-Ridgers, the company has achieved considerable improvements in many screening applications by selectively fitting torsional springs alongside coil springs.

“It is well known that the vibrating motion of a screen impacts on the building and structural accessories around it,” Mayhew-Ridgers says. “This vibration is addressed by fitting isolators between the screen and the plant floor, and by constructing the plant building to certain minimum structural specifications.”

However, the focus is often on the frequencies that the screen generates in its steady-state phase – or the normal running phase – rather than during the transient phases when the screen is starting up or slowing down to a stop, Kwatni says.

Mayhew-Ridgers highlights that it is during these transient phases that the screen’s movement becomes amplified and potentially most destructive. Isolators between the screen and the floor – common among which are coil springs and rubber buffers – are meant to absorb vibrations and prevent damage to surrounding infrastructure. However, the transient phases, especially when stopping, can generate considerable sideways movement of the screen, which must be avoided.

“Traditional isolators like coil springs usually perform well in controlling the up-and-down movement of the screen,” he says. “Our experience is that the sideways movement, which is induced most strongly when the machine stops, can be better controlled by torsional springs.”

However, he notes that coil springs retain the advantages of being cost effective and providing a good linear isolation of the screen from the building structure. In this respect, their isolation characteristics are generally better than rubber buffers which excel in terms of their damping qualities.

“The torsional spring provides the best of both worlds, giving a good linear range for compression during operation while also becoming non-linear like the rubber buffer during stopping,” Mayhew-Ridgers says.

Using its experience observing screens operating in the field, Kwatani has developed and trialled various solutions in its dedicated testing centre at its headquarters in Kempton Park, South Africa. By optimising the best combination of coil springs and torsional springs, the company says it has succeeded in achieving the best results for customers.

“It’s not that torsional springs are better than coil springs,” Mayhew-Ridgers says. “It is about finding the right combination – through intensive testing and adaptation – for the customer’s particular requirements; we have both the expertise and the equipment to do this.”

Metso Outotec to provide ‘unique’ sustainable screening tech to iron ore project

Metso Outotec says it will supply unique sustainable screening technology for an iron ore project in the Southern Hemisphere.

The order for the product screening and scalping application covers 12 Metso Outotec BSE Series™ (Banana Screen Elliptical) tandem screens and 4 MF Series™ screens, all equipped with 305PS screening media. In addition, the contract covers Metrics monitoring system for screens, expert support and installation services, the company says.

Metso Outotec explained: “The need to reduce water in iron ore production and other minerals processing is a critical global challenge. The innovative and patented BSE Series screens enable iron ore processing even with higher natural moisture content without adding water.”

The order value, which is not disclosed, has been booked in Minerals segment’s September quarter orders received. The start-up of the project is scheduled for the first half of 2024.

Jouni Mähönen, Vice President, Screening business line, Metso Outotec, says: “We are pleased that the customer chose Metso Outotec for sustainable screening solutions for their process. The BSE screen is an outstanding option for their needs. The elimination of process water ultimately results in lower processing costs, increasing the customer’s competitiveness and profitability in the iron ore global markets.”

Results the customer can expect after implementation, according to Metso Outotec, include:

  • BSE Series screens, which are part of the company’s Planet Positive solution, enable elimination of process water in the screening process;
  • A 93% reduction of the plant’s overall water consumption, elimination of the need for tailing dams;
  • Reduced energy consumption from the entire plant compared with the wet screening process: 18,000 MWh/y electricity saving;
  • 30% increase in screening capacity compared with traditional screening;
  • Increased safety during media change-outs using the Hammerless Attachment system; and
  • Reduced capital expenditure due to the adoption of high-performing BSE screens.

MOBISCREEN MS EVO screening plants hit the mark at Orissa Mining’s iron ore site

Wirtgen Group’s Kleemann MOBISCREEN MS EVO screening plants have been helping Kalina Commercial Corp and Orissa Mining hit their goals at the Keonjhar iron ore mine in Orissa, India, classifying material into the desired grain sizes.

Kalinga, which is responsible for iron ore extraction on behalf of the state-owned company Orissa Mining, has been using six MOBISCREEN EVO mobile screening plants from Kleemann to classify the iron ore in up to four fractions.

More than 20 excavators are deployed for extraction, handling and loading of the ore, with 140 large dump trucks transporting the material from the mines for further processing by the screening plants.

Five double-deck screening plants MOBISCREEN MS 952 EVO and a triple-deck screening plant MS 953 EVO make classification of the blasted and then crushed material into up to three or four (with the MS 953 EVO) fractions possible.

With the use of these six mobile classifying screens, Kalinga has achieved a continuous daily production target of 30,000 t in two shifts and the desired final grain sizes of 0-10 mm and 10-40 mm.

The MOBISCREEN MS EVO screening plants are able to operate precisely and efficiently under extreme conditions: in the open-pit mining site in Keonjhar, they process feed material with a moisture content of 6-7% without issue.

Dr SR Samal, Managing Director, Kalinga Commercial Corp, said: “We have been using Kleemann screening plants for more than two years. These plants have proved their value with regard to product quality and output. Over the years, they have become an indispensable element of our operation. The service, above all, is exemplary. The co-operation with the Wirtgen Group was crowned with success.”

The classifying screens in the EVO series provide high productivity, good transport properties and first-class screen results, according to Wirtgen. The product series includes the two double-deck classifying screens MS 702 EVO and MS 952 EVO, as well as the triple-deck classifying screens MS 703 EVO and MS 953 EVO. Thanks to the particularly large screening surfaces of 7 sq.m or 9.5 sq.m, high production outputs, combined with effective screening of up to four first-class final products, can be achieved, the company says. Depending on the application case, throughputs of up to 350 t/h (MS 702 and MS 703 EVO) or 500 t/h (MS 952 and MS 953 EVO) are possible.

With the MOBISCREEN EVO screening plants, Kleemann has also considered safety. The plants can be operated with an intuitive control system via a mobile control panel that can be attached at three different points of the plant. This increases work and operational safety.

Easily accessible work platforms mean service activities can be carried out quickly and screen surfaces can be replaced without any problems, the company says. All other service components can be accessed from the ground so maintenance tasks can be executed without complications.

TerraSource to highlight high-performance crushing and feeding equipment at MINExpo

TerraSource Global and its three flagship equipment brands – Gundlach, Jeffrey Rader and Pennsylvania Crusher – are gearing up to showcase new products at MINExpo International that, TerraSource says, are helping the company remain an innovation leader in durable, high-performance crushing and feeding equipment for the mining industry.

The company’s products are known to many in the sector, with a list of crushing and feeding solutions that include roll crushers, jaw crushers, hammer mills, impactors, cage mills, vibratory feeders and centroload feeders.

At MINExpo in Las Vegas – September 13-15, 2021 – TerraSource’s booth highlights will include the EnduraHog™ hammer mill, which takes the best of its Jeffrey Rader hammer mills and hogs for a new industry standard of flexible, durable, and low-maintenance crushing equipment; and its EnduraHog Flextooth® crushers, which couple unique hammer designs with patented Slant-Flow® screen grates – designed to facilitate more uniform sizing capabilities, faster material evacuation and longer wear than other types of grates.

“Not only are these machines designed for durability, high performance and energy efficiency, but our new EZ-Access™ housing design also makes these machines safer and easier to maintain than competitor models,” TerraSource said.

Also on show will be the company’s line of premium-performance Duralife® hammers and Brute Armor™ wear-resistant screen grates.

“Many of our mining customers have presented us with particularly challenging material sizing applications that require specialised hammers and striking surfaces with enhanced performance characteristics and wear resistance,” the company said. “TerraSource has met these challenges with our Duralife and Brute Armor premium OEM parts offerings, the result of years-long investment in patented chemistry and material compositions, advanced design features, and proprietary production processes to provide the highest-performing wear parts options – up to four times longer life than third-party offerings – for customers with the toughest material sizing requirements.”

And new Jeffrey Rader NFE vibratory feeders will also be displayed.

The Jeffrey Radar NFE provides additional size configurations along with the most-requested design upgrades to ensure even more precise feeding capabilities coupled with simpler and safer maintenance features, greater energy efficiency, and lower overall cost of ownership, the company claimed.

Finally, the redesigned Gundlach Cage-Paktor® maintenance cage mill (pictured) for finer grind, higher volume and fewer fines applications will be shown off to attendees. The redesigned Gundlach Cage-Paktor is equipped with, among other elements, thicker, more wear-resistant materials over the entire cage; improved resistance to breakage from tramp; and no-wear liners and bolted-on components for easier, faster and less-expensive maintenance.

Haver & Boecker Niagara’s Pulse Vibration Analysis to feature at MINExpo 2021

Haver & Boecker Niagara is to showcase its Pulse Vibration Analysis (VA) software at the upcoming MINExpo 2021 event in Las Vegas, USA.

Providing mining and aggregate operations insight into their equipment’s performance, Pulse VA is specifically designed to examine the health of a vibrating screen to ensure optimum screening performance and equipment reliability, according to the company. It detects irregularities that could translate into diminished performance, decreased efficiency, increased operating costs and imminent breakdown.

Pulse VA will be front and centre of the Haver & Boecker Niagara booth at MINExpo 2021, taking place on September 13-15.

Karen Thompson, President of Haver & Boecker Niagara’s North American and Australian operations, said: “We understand screening equipment is a significant portion of an operation’s budget, which is why we developed Pulse VA. Pulse VA offers operations the tools to optimise screening efficiency on a daily basis. This helps increase their operation’s profitability by minimising downtime as well as maintenance costs.”

Pulse VA is designed to be easy to operate, with components specifically chosen and engineered for the harsh environment where screening takes place. The system uses an industrial-grade tablet computer that connects wirelessly with eight tri-axial sensors, which attach to key places on the equipment and send up to 24 channels of data to the tablet. The table then displays a real-time view of the machine’s orbit, acceleration, deviations and more, Haver & Boecker Niagara said.

Beyond the real-time view on the screen, all information from the sensors is electronically stored in the database for an historical overview of the machine, with the information downloadable online in two report formats. The Orbit Report provides a visual of orbit and wave form, as well as data about acceleration, stroke, speed and phase angle. Fast Fourier transformation, or FFT, plots are processed by the software for values for three channels of data for each measuring point. The Tuning Report extrapolates deviations between measurement points while providing recommendations on balance, acceleration, stroke and speed. It provides feed and discharge analysis as well as diagonal measurements.

Haver & Boecker Niagara says it also offers its signature Pulse Vibration Analysis Service program to help customers achieve production targets, minimise unscheduled downtime and demonstrate sustainable improvements through online asset management, it said. The service program includes a complete vibrating screen inspection by a Haver & Boecker Niagara certified service technician, along with a Pulse Diagnostic Report.

Pulse VA technology, the company says, serves as a critical part of PROcheck, Haver & Boecker Niagara’s service process dedicated to keeping customers’ operations running at peak performance. PROcheck applies Haver & Boecker Niagara’s expertise in diagnostics, processing equipment, engineered screen media, original parts, rebuilds and upgrades, services, plants and process engineering to inspect customers’ screening processes in order to recommend best practices for processing proficiency.

Cedric Minería selects CDE EvoWash wet processing tech for Buin sand, gravel ops

Chilean mining and aggregates company, Cedric Minería, has announced a major overhaul of its aggregates business following a significant investment in advanced wet processing technology from CDE, the Belfast-based company says.

The family business, which expanded into aggregates production in 2003, has revealed plans for a new wet processing solution at its Buin operation.

Established in 1981, Cedric Minería specialised in the production of calcium carbonate and sulphur products before diversifying its interests and launching its silica operation, Mina Nancy, near the city of Calama in Antofagasta Region.

It soon secured listing as a strategic supplier of silica to state-owned copper mining company Codelco for its copper smelting plant in Chuquicamata, northern Chile.

Following the success of its silica business, Cedric Minería soon after commissioned its first aggregates processing plant in Buin which supplies the local market with a range of washed sand and gravel products for pre-cast concrete, asphalt, pipe bedding and more.

This summer, CDE will commission the EvoWash™ sand wash plant and an AquaCycle™ water management system at the company’s Buin site, replacing their existing washing screws.

Using CDE cyclone technology, the new plant will enable Cedric Minería to produce two grades of high quality, in-spec fine sands: 0-5 mm and 0-8 mm.

A compact, modular sand washing system, CDE’s EvoWash screens and separates the smaller sand and gravel fractions through an integrated high-frequency dewatering screen, sump and hydrocyclones which provide control of silt cut points and eliminates the loss of quality fines with significant commercial value.

An alternative to water extraction and the costly process of pumping water to the plant, CDE’s AquaCycle significantly reduces costly water consumption by ensuring up to 90% of process water is recycled for immediate recirculation, the company says. It helps to accelerate return on investment by maximising production efficiency, minimising the loss of valuable fines and reducing water and energy costs. A single, compact and user-friendly unit, it can be applied to high and low tonnages across many market sectors.

Cedric Minería owner, Cedric Fernández, says the investment in CDE technology is a significant step forward for the company.

“We’re making a huge technological leap forward with this new plant. Cedric Minería branched into the aggregates business almost two decades ago and throughout that time we have operated a traditional system,” Fernández said. “The existing plant has served us well, but we need a modern solution that is future-ready. Our latest investment in CDE wet processing technology represents the beginning of a new chapter for our company.”

Fernández says the COVID-19 pandemic had a significant impact on the construction industry but anticipates strong future demand for sand and aggregates to support the country’s public works investments.

CDE Business Development Executive, Gustavo Brasil, says older technology is very much under the spotlight for materials processors as they work to remedy inefficiencies.

“Recognising the limitations of the existing setup, the team at Cedric Minería are setting out on an ambitious transformation project to replace a traditional processing plant with a much more advanced and efficient technological solution,” he said.

The CDE solution engineered for Cedric Minería will revolutionise its current process, he added.

“CDE’s Evowash solution will enable Cedric Minería to produce superior fine sands with less moisture content while the AquaCycle water management system will deliver massive efficiency gains by recycling process water and driving down operational costs,” he said.

Pilot Crushtec and Metso Outotec extend partnership

After five years representing global leader Metso Outotec in southern Africa, South Africa-based Pilot Crushtec has renewed its distributorship for another half decade.

Pilot Crushtec, despite periods of challenging economic conditions in recent years, has earned global accolades within the Metso Outotec distributor network, with Francois Marais, Director Sales and Marketing at Pilot Crushtec, saying the company has already won annual awards for Best Aftersales Distributor and for Best Sales Growth.

“We value this partnership with one of the world’s leading brands and have demonstrated through our solid performance the positive synergies that we leverage,” Marais says. “The years from 2017 through to 2019, in particular, saw exceptional growth year-on-year for both our Metso Outotec offering and our business as a whole.”

He highlights that the two companies’ offerings in the crushing and screening market complement each other very well, and they share a commitment to high quality products, service and support.

“For customers, the renewal of our distributorship confirms their faith in our products and strengthens their security of investment going forward,” he says. “It assures the market once again that their capital investments are being well supported through our extensive parts holdings and service excellence.”

The new agreement covers additional products and territories within the region, facilitating a wider offering in terms of new equipment and aftermarket aspects. According to Adam Benn, Director Capital Sales, North EMEA, Russia & CIS and Southern Africa at Metso Outotec, there was no hesitation in renewing the distribution agreement with Pilot Crushtec.

“Having just celebrated its 30th anniversary in business, Pilot Crushtec has built a strong reputation,” Benn says. “This applies not only to their supply of equipment and associated services, but their experienced team’s hands-on knowledge and can-do attitude to opportunities and challenges.”

He emphasised Pilot Crushtec’s investment in time and resources training their teams and their customer base – an effective strategy for keeping skills current and for listening to customers’ development needs. With technical facilities that, it says, rank among the industry’s best, the company manufactures plant locally while also offering a one-stop repair and refurbishment solution.

“Having a distribution network that is close to its customers is a fundamental part of Metso Outotec’s group strategy,” he says. “In addition to being well located, our distributors need to keep a good inventory of equipment and parts, which is something that Pilot Crushtec prioritises as a vital cornerstone of their business strategy.”

Metso Outotec boosts end-user service offering in central, southern Sweden

Metso Outotec has signed a distribution contract with Mining and Construction Equipment Sweden AB and Värnamo Krosskonsult AB that will see the two Sweden-based firms distribute Metso Outotec’s mobile and stationary crushing and screening equipment, as well as crusher wear parts, to mining and aggregate customers in southern and central Sweden. The pair will also provide service support such as start-ups and repairs in the regions.

Roar Vasbø, who is heading Metso Outotec’s sales and service in the Nordics region, said: “We’re very pleased to enter this cooperation. For the customers, it means better and faster local service. For us, it means that we can improve customer experience and reach out to more potential customers in the region, especially contractors.”

Fredrik Wennberg, Managing Director of Mining and Construction Equipment Sweden, said: “Our aim is to serve the markets as one-stop-shop. We offer service, parts, equipment and know-how close to the customer.”

He added: “Flexibility is very important to our customers, especially for the contractors. We offer rental possibilities and stock units so that the customers are able to get their equipment quickly.”

Kristofer Almén, Managing Director of Värnamo Krosskonsult, concluded: “This is a great opportunity for us to be able offer Metso Outotec aggregate equipment to greenfield projects or to brownfield stationary plant projects. It will strengthen our competitiveness and help us serve the market better.”

The main location is Värnamo with equipment and parts stock, and a service workshop. Sales offices are in Stockholm, Värnamo and Ystad. The staff includes around 20 personnel in service, sales, and construction engineering.

MLG Oz bolsters NSR Jundee work, adds Norton Gold Fields and Mincor to contract mix

MLG Oz says it continues to experience historically high levels of tendering opportunities for its suite of mining services, with three new integrated site services and haulage contracts recently added to its remit across its Western Australia operations.

MLG, which listed on the ASX earlier this year, says it offers a range of value added services from bulk haulage, crushing and screening, aggregate and sand supplies through to export logistics.

At Northern Star’s Jundee gold operation in Western Australia, the company has been awarded preferred contractor status for an expansion of its services, providing integrated site support and haulage capacity at the mine. Subject to negotiation and execution, this new three-year contract is expected to commence around August and deliver some A$12 million/y ($9.2 million/y) in revenue.

The scope of works will consist of integrated site support to the company’s mill feed operations from both its Jundee central underground mines and its regional satellite operations, MLG said. It will see the ASX-listed contractor conduct all crusher feed, bulk haulage and site civil works for the operations under its integrated operating platform.

MLG has added two new clients to its roster, too – Norton Gold Fields and Mincor Resources.

Norton Gold Fields has chosen MLG as its successful tenderer to provide integrated site support services and haulage for its Paddington gold operation over a three-year period expected to commence in September. Revenue from this opportunity is estimated to be around A$14 million/y, with formal contract documentation anticipated to be finalised in the coming weeks.

And, in line with MLG’s desire to broaden its service offering across different commodities and, in particular, the battery metals space, it has executed a contract with Mincor Resources for the provision of the logistics services associated with its Kambalda nickel operation. The contract is expected to deliver approximately A$3 million/y in revenue over four years and is expected to commence in the March quarter of 2022.

Reviewing these contract awards, MLG Founder, Managing Director and majority shareholder, Murray Leahy, said: “We are very pleased to be given the opportunity to continue to support and grow with Northern Star which has been a long-standing customer of MLG.

“We are delighted that the Norton Gold Fields Board has selected MLG to support the Paddington processing facility. The mill is 35 km northwest of Kalgoorlie and aligns very strongly with our existing Kalgoorlie network.

“Our new contract at the Kambalda operations is an important first step for MLG in developing a longer-term relationship with Mincor in support of its goal of being a key supplier of nickel to the emerging battery metals market.”

In addition to announcing these contract awards, MLG also provided a market update on its crushing and screening activities.

It said: “MLG’s crushing and screening operations, which account for 20% of MLG’s forecast financial year 2021 revenue of A$241.6 million, have experienced a reduction in available material to process from several clients across the last quarter of financial year 2021, due to production constraints at various client operations. We anticipate this will negatively impact the crushing and screening revenue in the first half of financial year 2022. Despite this, and given the company’s current pipeline, including as evidenced above, the board expects the overall impact of this to be mitigated in the second half of financial year 2022.”

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