Tag Archives: Weir Minerals

Weir Minerals looks to keep slurry moving with new lubrication system

Equipment maintenance, Mineral processing, Mining equipment, Mining maintenance, Mining services, Water management, , , , ,

Weir Minerals has announced the global launch of a new lubrication system that, it says, can prevent bearing assembly failures, reduce maintenance downtime and promote safety.

The launch of Accumin™ lubricators follows international demand for the grease lubrication that has been ensuring optimal performance for equipment such as Warman® slurry pumps in Asia Pacific since 2014, Weir said.

Across more than 100 sites, the Accumin lubrication system has proven itself an efficient way of preventing expensive bearing assembly failures, reducing maintenance downtime and promoting safety by decreasing the amount of manual interface to keep equipment performing, the company said.

Making the move to Accumin lubricators helped one Australia iron ore mine save almost A$120,000/y ($73,705/y) in downtime reduction, pump rebuilds and bearing assembly replacements, Weir explained.

Michael Roinich, Accumin Specialist, Weir Minerals, said: “At Weir Minerals, we make the market-leading slurry pump for mining applications, but we can’t always control what happens when it gets to site. Between dust, overflow and gland seal leaks, lubrication is a vital tool in the constant battle to keep machinery going. Having an Accumin lubrication system fitted prevents over and under greasing, protects equipment from bearing failures and frees up man hours for more critical tasks.

“When we offer Weir Minerals equipment with an Accumin lubrication system installed, what we’re really doing is giving that equipment its best shot at a long and productive working life.”

Made in Germany, Accumin canisters are produced in 125 cm³ gas driven; 120 cm³, 250 cm³ and 500 cm³ electro-mechanically driven configurations, and can be deployed up to five metres away from the lubrication point, allowing easy and efficient access to the mount, Weir says. The electro-mechanical driven lubricator dispenses a consistent dosage of lubricant, regardless of ambient temperature. The system delivers 6 bar of operating pressure and can be monitored via an LCD display, flashing LED alert system and a transparent grease cartridge.

Roinich added: “Designed to meet the arduous demands of the mining industry, Accumin single-point lubricators set the global standard for lubricating Warman pumps and other grease-lubricated, mission-critical mining equipment supplied by Weir Minerals.

“We’re excited to share our market-leading, best-practice system with mines around the world who are embracing new technologies to simplify their operations.”

Weir Minerals bolsters Lewis pumps, valves range

Mineral processing, Mining equipment, , , , , , ,

Weir Minerals has made three new additions to its Lewis® range of pumps and valves for the sulphur, sulphuric and phosphoric acid industries.

The release of the Lewis VL Axial Pump, Lewis Horizontal Process Pump and Lewis Vertical High Pressure Molten Salt Pump marks a new chapter in the brand’s history of innovative product and material engineering, it said.

The three pumps have been designed to maximise wear life in some of the world’s most corrosive industrial applications while simplifying maintenance through their streamlined designs, according to Weir. This has significantly reduced the number of parts compared with previous pumps, without compromising their performance, it says.

Jerry Ernsky, Lewis Product Manager, Weir Minerals, said: “Although they’re designed to address different challenges, these three new pumps were guided by the same core design principles: using advances in material technology to achieve increased performance and wear life, while reducing complexity to simplify equipment maintenance and give us the flexibility to deliver more engineered to order features that benefit our customers.

“Fundamentally, Weir Minerals is in the business of solving tenacious problems that interfere with our customers’ operations, which is why every step of our product development is guided by our customers’ key challenges.”

The new Lewis horizontal process pump combines the long-lasting corrosion and wear resistance of Lewmet® alloys with the robust performance, efficiency and ease of maintenance associated with centrifugal pumps, Weir said.

“This single stage, end suction horizontal process pump is the product of years of experience and research, which perfectly complements the existing range of Lewis vertical acid pumps and valves,” the company added.

According to Ernsky, the pump is suitable for a wide variety of chemical processing applications, offering efficient performance and superior wear resistance to the growing number of acid plants and fertiliser complexes operating around the world.

“Our engineered to order horizontal pumps are customised to support our customers’ goals of reducing plant maintenance and achieving a lower total cost of ownership,” he said.

The new Lewis VL Axial Flow Pump offers heavy duty construction ideal for use in corrosive, high temperature chemical processing applications, such as evaporator and crystalliser circulation, according to Weir. Its design is highly flexible and can be customised to suit a wide variety of industrial applications, while its low component count makes servicing quicker and easier, the company said.

The Lewis Vertical High Pressure Molten Salt Pump has been designed to meet the needs of the burgeoning concentrated solar power industry, Weir said. This multi-stage vertical turbine pump can handle the multifaceted challenges that come with the extremely high pressures and temperatures associated with pumping molten salt for thermal energy storage, according to the company.

Weir Minerals solves ‘dirty water’ fluid transfer problem with Warman DWU pump

Environmental, Mining equipment, Water management, , ,

As IM goes to press on its March print issue and a feature on dewatering, sector leader Weir Minerals is stressing the importance of using a fit-for-purpose pump that can handle “dirty water”.

While the market offers specialised slurry pumps to handle thick and abrasive slurries, as well as submersible and sump pumps for pumping clean water, neither of these options provide an effective solution for pumping dirty mine water, Weir Minerals says.

The company has leveraged its extensive knowledge of pumping slurries and developed the Warman® DWU (Dirty Water Unit) pump, designed to handle both increased suspended solids in dirty water while operating at high discharge head pressures.

“The introduction of, and subsequent clogging from, suspended solids is one of the most common causes of premature failure in a dewatering pump,” Weir Minerals says. “‘Upset’ conditions during the underground mining process are the general cause of increased suspended solids levels entering the mine’s dewatering discharge water.”

The Warman DWU pump combats both these challenges, transporting the dirty mine water to its designated discharge point via single (140 m), multi-stage (480 m) portable, or permanent pumping solutions, the company says.

‘Dirty water’ is the name given to water with too high a percentage of suspended solids to considered be ‘clean’, but too low of a percentage to be classed as slurry, Weir Minerals says. “Dirty water becomes a problem onsite when the solids concentrate inside a dewatering pump collects around the motor frame, overheating the pump and causing the motor to fail.”

The Warman DWU pump is, Weir Minerals says, specifically designed to handle dirty water from onsite ponds and open pits with specific gravity of up to 1.05. Where a pump built to handle clean water will fail once dirty particles are introduced, the DWU pump will not, according to Weir. “That is because the DWU was designed using computational fluid dynamics and utilises Weir Minerals’ advanced material technology, allowing the DWU pump to process the fluid efficiently and minimise pump maintenance in the long run,” the company said.

Marnus Koorts, Product Manager for Pumps at Weir Minerals Africa, said: “In most circumstances, high-head clean water pumps will fail when they are required to process even a minute amount of particles. Once you have greater than 1% of particles, a site’s only other option is to install slurry pumps.”

Slurry pumps are commonly used to address the dirty water problem, but this solution is costly and inefficient, according to Weir Minerals.

“Without a specialised dirty water pump like the Warman DWU, up to three slurry pumps need to be sourced, installed, and maintained just to pump the dirty water as far as a single Warman DWU pump can,” the company said. “The pump utilises a new high-pressure casing to withstand pressures up to 7,000 kPa, enabling it to pump operating at maximum speed and achieve a head of 140 m at the best efficiency point.”

Koorts summarises: “This results in a lower total ownership cost and reduced downtime for the customer while providing them with increased efficiency and energy savings over using slurry pumps in the same application.”

The Warman DWU pump provides a solution to a fluid transfer problem that can quickly affect an entire operation, according to Weir Minerals. “By making use of the latest Warman WBH® mechanical end design, customers benefit from 90% common component interchangeability, allowing them to reduce stockholding of spares,” the company said. “In addition, the Warman DWU pump is available with either an electric or diesel motor and can be mounted on either a pontoon, skid, or trailer, which provides sites with the flexibility to move the pump around to where it’s needed.”

Koorts said: “Pontoon mounting an electric DWU pump allows for series pumping at base level or stage pumping out of an open pit. With Weir Minerals’ dewatering expertise we’re able to engineer a complete solution that places the suction end of the pumps into the water, while the pump and motor are mounted at an angle above the water line. This keeps the suction end of the pump submerged and eliminates suction problems. With a diesel driven pump, we install a vacuum assisted priming system that reprimes the pump when needed.

“Essentially, customers can set and forget.”

The Warman DWU pump provides a flexible dewatering solution to sites, not only in the portability around site, but in the range of fluids the pump is built to handle, Weir Minerals says. “In the nine years the pump has been on the market, Weir Minerals engineers have continued to improve the DWU’s capabilities.”

Although designed to handle dirty water, the Warman DWU pump is also able to process clean water with 78% efficiency, and the addition of a stainless-steel casing means the DWU pump is now suitable for highly acidic applications (pH >2), according to Weir Minerals.

Weir Minerals Africa putting newly designed vibrating screens to the test

Comminution of minerals, IoT, Mineral processing, Mining equipment, Mining services, , , , , , ,

Weir Minerals Africa, having over the last 40 years proven the credentials of its Enduron® range of vibrating screens, is now locally designing and manufacturing new-generation linear motion vibrating screens.

One of these new, modern screen designs is part of a recent Weir Minerals Africa complete comminution plant contract for a South Africa mining project. The scope included two crushing stations, a screening station and all the related feed chutes, bins and conveyors.

According to Christian Stehle, Head of Engineering at Weir Minerals Africa, the company’s design capability provides the flexibility to produce vibrating screens to suit each customer’s plant layout. At the same time, the designs will optimise cost, efficiency and performance. South Africa also hosts Weir Minerals’ global screening and separation technology group.

“This expertise ensures that our robust Enduron vibrating screens provide exceptional classification and dewatering screening performance,” Stehle said. The screens are deployed in a wide range of minerals processing applications.

He noted that vibrating equipment is generally more challenging to design than static equipment due to the high frequency cyclic loading to which the machines are subjected.

“The final design must address key criteria like screening efficiency, throughput and loading, while still operating within the acceptable fatigue life limits of the materials of construction,” he said.

Stehle highlighted that the use of finite element analysis (FEA) tools allow engineers to optimise screen life by obtaining the stress and deflection levels in the equipment and applying the appropriate structural design and utilisation of materials in the areas experiencing high stresses.

“Traditionally, screen designs used to be heavier in an effort to extend the life of the equipment,” he said. “Using FEA tools during the design stage allows us to retain structural integrity while actually reducing the overall weight of the machine.”

While there are areas of high stress on the equipment that need more strength, technology tools indicate where lower stresses occur. In these areas, less steel can be used to make the structure lighter, according to Weir Minerals Africa. Leveraging this technology, the weight of some new-generation screens has been cut by up to 15%, the company said.

Stehle noted that Weir’s Synertrex™ IoT platform can also be applied to monitor and improve the performance of the company’s vibrating screens. Synertrex technology is an industrial internet of things system that allows operators to monitor every aspect of their equipment’s operation, to prevent problems and increase throughput.

Weir Minerals improves plant uptime at mineral sands, gold mines

Comminution of minerals, Equipment maintenance, Industrial minerals, Mine operation news, Mineral processing, Mining consumables, Mining equipment, Mining maintenance, Precious metals, , , , , , , , ,

Two African mines are achieving increased production time and plant availability after converting to Weir Minerals rubber lining solutions, the company says.

A mineral sands operation in Mozambique approached Weir Minerals just over two years ago, after experiencing high wear on its pipe and launders. This was leading to frequent maintenance, leaks and downtime. The Weir Minerals team observed that part of the challenge was worn out and corroded metal work on the mine’s wet concentrator plants due to the proximity to the coast.

Access to reline the existing launders was difficult and posed safety risks necessitating a more effective solution, the company said.

The solution was to replace the competitors’ products – chemically-cured rubber – with Linatex® rubber and Linard® 60 rubber. This was done during the mine’s monthly shutdowns.

Whereas the competitors’ rubber lasted only two to three months, the Linatex and Linard linings are still in operation after 25 months, according to the company.

The Linard 60 rubber lining solution was also applied at a gold mine in South Africa’s North West province. The mine’s maintenance team had been replacing the rubber lining on mill feed hoppers and spouts every 10 days, but the Mechanical Foreman was looking for a more resilient solution.

The Foreman was not familiar with Linatex rubber products, so a trial using Linard 60 rubber was arranged, with the entire feed hopper and spout lined with this silica-reinforced natural rubber.

The results saw wear life increase to 12 weeks. With only the partially worn areas requiring relining, there was a reduction in relining costs. This, in turn, increased plant availability, resulting in fewer stoppages and reduced operating costs.

Linatex premium rubber is a proprietary vulcanised natural rubber produced through a process that uses high quality natural latex, according to Weir. “It has outstanding strength, resilience and resistance to cutting and tearing – with high performance in wet, abrasive conditions,” the company said.

Linard 60 rubber, which is silica reinforced, retains the natural strength and nerve of latex, while combining with the toughness needed for handling coarse materials, according to the company.

Weir Cavex hydrocyclones take a load off at OceanaGold Didipio mine

Base metals, Comminution of minerals, Equipment maintenance, Mine operation news, Mineral processing, Mining equipment, Mining maintenance, Mining services, Precious metals, , , , , , , , , ,

The installation of 19 Cavex® 400CVX10 hydrocyclones at OceanaGold’s Didipio gold and copper mine in the Philippines has led to savings of more than $800,000/y through a dramatic reduction in grinding circuit recirculation, according to Weir Minerals.

The Didipio mine, which employs more than 1,500 workers (drawn predominantly from the local community), has expanded throughput over the last few years in line with its transition from open pit to underground mining. This increased the incumbent cyclones’ feed density beyond what they could effectively manage, leading to a circulating load of up to 700%, according to Weir.

The Cavex 400CVX10 hydrocyclones significantly improved separation efficiency due to their finely tuned spigot liner diameter and the strength and corrosion resistance provided by its cast housing, according to Weir.

Thanks to these qualities, the introduction of the Cavex hydrocyclones reduced the circulating load from 620% to 374%, with the direct savings in power consumption, ball consumption, cyclone and pump maintenance costs exceeding $815,000/y.

Gary Webb, Processing Manager, OceanaGold Didipio project, said: “Having had good performance from Cavex hydrocyclones at our New Zealand sites (Macraes and Waihi), we were confident that retrofitting Cavex hydrocyclone cluster at Didipio, with an increased number of smaller cyclones than we had at the time, would help reduce our problematic circulating load and lever multiple benefits in doing so.

“The changeover to Cavex hydrocyclones has exceeded our expectations, enabling higher throughput and lower consumable costs without being penalised in grind size.”

The performance of Cavex hydrocyclones can be attributed to the 360° laminar spiral inlet geometry design, which provides a natural flow path into the hydrocyclone, Weir said. This shape allows the feed to blend smoothly with rotating slurry inside the chamber, reducing turbulence.

Mike Arakawa, Philippines Country Manager, Weir Minerals, said: “Working with customers across the globe, our expert engineers are constantly looking at how they can maximise separation efficiency, hydraulic capacity and extend the wear life of not just the hydrocyclone, but our customers’ overall processing plants.

“I’m proud of the results we’ve achieved together with OceanaGold. Reduced circulation means reduced power draw, fewer balls consumed and less equipment wear, creating a more sustainable mine.”

Didipio produced 114,985 oz of gold and 14,999 t of copper in 2018, with 120,000-130,000 oz and 14,000-15,000 t of copper slated for 2019.

Weir Minerals Pumped Up by new dewatering game for miners

Environmental, Mining equipment, Water management, , , , , , , , , ,

Weir Minerals says it has created a “fun and simple game” to educate its customers on the OEM’s dewatering capabilities.

Pumped Up! uses a variety of Weir Minerals dewatering equipment to move water around a fictional mine site, according to Ian Ross, Global Product Manager for Dewatering at Weir Minerals.

Each of the 10 levels present players with a different dewatering obstacle to overcome, from recycling, to flooding, to underground mines and long distance pump requirements. Levels increase in difficulty, and the number of points awarded is determined by how long each level takes to complete.

Products included as part of Weir Minerals’ dewatering solution in Pumped Up! include Warman®, Geho®, Floway®, and Multiflo® pumps as well as Isogate® and Delta® valves, and Linatex® hoses.

The game was released as part of Weir Minerals’ 2019 Take Control Of Your Water dewatering solutions campaign. Through articles, expert profiles, and case studies, the campaign demonstrates how Weir Minerals use its engineering and project management capabilities, together with a wide range of equipment, to deliver an optimised dewatering solution unique to every customer site, the company said.

Head to www.dewateringsolutions.weir to play the game.

Weir to expand tailings dewatering offering with new ‘innovative’ solution

Bulk handling, Environmental, Mining equipment, Mining services, Water management, , , , , , , ,

As the Global Tailings Review prepares to issue a new industry standard in 2020, Weir Minerals has chosen now to examine the subject of dewatering tailings.

The company, already offering solutions to help dewater tailings, says it is developing an “innovative tailings dewatering solution” to allow operators to pump slurry containing an extremely high percentage of solids. It says it plans to launch the new technology in 2020.

Mike Swintak, Regional Senior Product Manager for Weir Minerals, said dewatering tailings can be a difficult process, yet, when undertaken successfully, “it can deliver significant benefits to mine operators”.

The foremost benefit of dewatering tailings is the reduction of water that needs to be transported from a process plant to a tailings storage facility (TSF).

Reduced water content means tailings slurry volume is decreased, allowing for smaller pipelines and pumping equipment to be used. This can also minimise power requirements.

Thickened tailings and paste can improve the stability of TSFs and diminish their footprint. In some instances where existing TSF capacities are limited by regulatory or other environmental considerations, thickened tailings can help to extend the life of the mine, Weir says.

“Proper containment of tailings reduces the risk to people and the environment, and when decommissioning a mine, thickened tailings facilities are easier to rehabilitate,” the company added.

To a growing extent, thickened tailings are also used for underground mine backfill. This can increase productivity and reduce mine cycle times as well as surface TSF disposal volumes. Underground mining conditions can also be improved due to decreased water and slimes handling.

Important considerations and challenges

“When tailings are not properly managed, the results can be lethal. It is vital that mine operators have a clear understanding of key risks and considerations related to this process, in particular, tailings dewatering,” Swintak said.

Every mine site is different and subject to varying environmental, regulatory, capital and operating cost constraints.

Cost is a key consideration for many operators and can adversely affect the viability of a mine site, according to Weir. Therefore, it is necessary to implement a tailings management strategy that provides both reliability and value for money.

“Environmental limitations are also a major factor when establishing a TSF,” Weir says. “In parts of the world where there is challenging topography, such as mountainous regions or other environmentally sensitive landscapes, TSFs may need to be built further away from the process plant. This can result in slurry being transported across longer distances or higher elevations. Dewatering of tailings is a viable option in these scenarios as less slurry needs to be moved, in turn reducing operational costs.”

Some operations produce highly diluted tailings that require extensive dewatering to reach the desired level of thickness. Other slurries may contain extremely fine particle solids that are also difficult to manage. Large mine sites, or those with complex orebodies, can produce many types of tailings waste slurries, which may require varying methods of treatment.

“Across this multitude of situations, the operator must determine all associated costs and assess the level of dewatering required to confirm the most suitable solution for their site,” Weir says.

“While some mines are in a position to increase the size of their TSFs, many are not, and must implement a viable dewatering process, which can involve significant capital expenditure.”

If dewatering tailings to the highest possible degree, operators also need to develop a suitable strategy for transporting the waste material. Tailings that are too thick to be pumped may need to be transported by either a conveyor system or truck.

Finally, when a mine site reaches the end of its life and moves into the decommissioning phase, TSFs must be dealt with in accordance with regulatory and legislative requirements. As many mine sites need to be rehabilitated and restored to a natural state, a key benefit of producing thickened tailings is its ability to be covered with overburden and re-planted with suitable vegetation.

Weir Minerals offering

“Weir Minerals realises dewatering tailings can be a daunting process for many operators,” it says. “In order to provide the highest level of support and service, the company has invested heavily in its tailings management capabilities. More than just a supplier, every mine site is assessed on a case by case basis to provide a complete tailings dewatering system customised to the customer’s applications and constraints.”

Swintak added: “From developing flow sheets and process requirements to supplying equipment including dewatering systems incorporating our Isodry thickeners and filters, Multiflo floating and mobile pump systems for use on tailings ponds, or GEHO positive displacement pumps capable of transporting high density slurries up to 200 km, we provide customers with peace of mind through our tailings solutions.”

A key point of difference, according to Weir, is the intensive pilot plant testing Weir Minerals can perform at the Weir Technical Centre in Australia. This facility is designed to test tailings samples from around the world to help ascertain the best way to process them in line with the customer’s requirements. Testing is conducted using thickeners/clarifiers, hydrocyclones, filters and centrifuges, as well as a comprehensive pipe loop facility for determining high density slurry pipeline design.

Weir Minerals can also conduct testing at customer mine sites to assess the viability of various tailings management strategies.

As the mining industry gains a better understanding of tailings, it is vital new and improved methods of containment and storage are developed.

“Weir Minerals believes that the dewatering of tailings has a fundamental role to play in this, and continues to push the boundaries of possibility,” it said.

Weir GEHO pumps keep up the pressure at SIMEC’s Whyalla steelworks

Comminution of minerals, Mine operation news, Mining equipment, Mining services, Steel and iron ore, Water management, , , , , , , , ,

Weir Minerals’ GEHO® positive displacement pumps are helping SIMEC Mining keep up its production goals at the Whyalla steelworks in South Australia.

SIMEC produces iron ore concentrate for the steelworks from a 10 Mt/y iron ore mine in the Middleback Ranges of South Australia, with the GEHO pump’s responsible for transporting the slurry 67 km from the plant to Whyalla, where it is then dewatered and converted to pellets for the steelmaking process. SIMEC has two GEHO PD pumps on site, which, through high pressure pumping, ensure the material stays suspended in the pipeline throughout the journey.

“The GEHO pumps transport the slurry about 250 cubic metres an hour, 300 tonnes an hour into town,” Chris Stanton, Senior Process Engineer, SIMEC Mining, said. “They run every day, all day and are very powerful pumps. They have defined maintenance intervals that allow us to run each pump for the nominal amount of time without any risk of breakdown.”

As the pumps are critical for both the plant and steelworks, it’s crucial they are well maintained to continue to perform year after year. This is made possible through the close partnership between Weir Minerals and SIMEC Mining, according to Weir.

Anthony Sheely, Concentrator Operations Coordinator, SIMEC Mining, said: “If the GEHO pumps didn’t operate properly then the pipeline would be at risk, and that would be a major issue as the pipeline is the lifeblood for both our operation and the entire township of Whyalla.”

Pumping long distance is a critical requirement at many mines around the world, but often comes with challenges and key design considerations that operators must be mindful of.

Peter Thissen, Global Product Manager for GEHO pumps at Weir Minerals, said: “The biggest challenge of long-distance pumping is generating slurry with a suitable particle size distribution for the application. Operators must concentrate the particle size distribution to make it a pumpable slurry whilst trying to minimise the amount of water used in the process.”

He added: “We deal predominantly with high solids concentrations, which is becoming more important in both a water constrained and environmentally sensitive industry. Our depth of experience and knowledge together with the delivery of innovative designs has provided effective solutions to meet our customers’ needs around the world.”

Designing a pipeline like the one for Whyalla is a complex balancing act between the rate of flow, the concentration of slurry and the size of particles, according to Weir. For solids in slurry to remain in suspension, they need to be moved by the liquid at a minimum velocity.

Another challenge operators are faced with is the pipeline route. This must be the most economic means of transportation and suitable for the flow behaviour of the material.

Thissen says: “It’s much easier to build a pipeline on flat land as it stays horizontal and the operational condition for the materials is constant, as long as we can keep the particles in suspension. However, if we have to cross rivers, mountains or valleys then the pipeline will be built on an angle and great consideration must be given to the design of the pipeline, transport velocities and starting and stopping the pipeline.”

Weir Minerals’ GEHO crankshaft driven pumps are among the world’s most advanced positive displacement pumps, according to Weir. They are designed to transport slurry over long distances, reaching up to 550 km and more than 2,000 m uphill.

Thissen says: “Our GEHO pumps are designed to handle high-density slurry with solids up to 85%. With extremely high availability, low energy consumption and operating costs they ensure uninterrupted, trouble-free operation.”

The diaphragm in the pump separates the abrasive slurry from the operating components, with the exception of the valves, protecting them from wear and ultimately prolonging the life of the pump, according to Weir.

“What this means for the operator is significant savings for wear parts, resulting in a very economic and extremely reliable product for pipeline transportation,” Weir said. “If maintained properly the GEHO pumps continue to run year after year, 24 hours a day; with references of GEHO pumps in operation for 30+ years.”

Thissen concluded: “As long as the make-up of the slurry doesn’t change and pumping conditions remain the same, our GEHO pumps will continue to operate indefinitely. Combined with long maintenance intervals and highly dedicated service engineers, they keep processing plants operating at peak performance while delivering a low total cost of ownership.”

Weir Minerals gives its skew view on HPGRs

Comminution of minerals, Environmental, Equipment maintenance, Mineral processing, Mining equipment, Mining maintenance, Mining services, Power supply for mines, , , , , ,

With industry demand for high pressure grinding rolls (HPGR) on the up, Weir Minerals is arguing that skewing is a vital feature for modern HPGRs to reduce wear, save downstream energy and ensure optimal grinding across the whole feed.

The company was sharing its findings following the publication of a new white paper.

Weir said: “With their excellent throughput capacity, low maintenance requirements and energy efficiency, HPGRs are fast becoming a go-to for greenfield projects looking to maintain their margins despite commodity price pressures and declining ore grades.”

The mineral processing company said, in the June quarter, that it had registered strong demand for its Enduron® HPGR technology during the three-month period, later on in the year confirming a major order, which included this comminution equipment, from Fortescue Metals Group for its Iron Bridge magnetite project in Western Australia.

Henning Knapp, HPGR Process Team Leader for Weir Minerals, said the applications from this equipment have evolved from the cement production days of the 1980s and are increasingly being deployed as tertiary and quaternary crushers in mineral comminution circuits, dealing with tougher ores including iron, gold, copper and diamonds.

“As any engineer will tell you, it’s almost impossible to eliminate feed variance and segregation completely. In the past, this has posed a critical challenge for HPGR operators – but dynamic skewing such as that featured in the Enduron HPGR, maintains optimal pressure across the entire feed.”

Traditionally, HPGR manufacturers have shied away from skewing designs, for fear of roller misalignment creating unfavourable load distributions, and preventing the use of flanged guards to reduce the edge effect, the company said. “However, Weir Minerals’ unique roller bearings design allows for skewing alongside effective edge guards, reducing wear and promoting better grinding.”

The downside of static rollers

A HPGR reduces particles by compressing and crushing the feed between two equally sized, parallel rollers rotating in opposite directions, with a small gap between them. This compresses the feed to 80% of its solid density, where the force of the rollers pushes the rocks against each other and exceeds their compressive strength.

“Inter-particle comminution avoids the direct component wear caused by conventional comminution techniques, and applies immense pressure, up to 27,000 kN, across the entire particle size distribution, which creates the higher proportion of fines HPGRs are renowned for,” says Knapp.

However, segregated feeds can result in markedly uneven particle sizes across the width of the feed, creating high, abrasive pressure on one side of the roll and insufficient pressure on the other. It will also produce a coarser product, requiring more work downstream, according to Weir.

“To compensate for the edge effect, a lateral wall or ‘cheek plate’ is deployed on either side to prevent material exiting the gap between the rollers sideways. The closer this is to the rollers, the better – but that has prevented engineers from introducing the flexibility needed to cope with feed segregation,” explains Knapp.

How Enduron HPGRs skew to maintain optimum pressure

To accommodate this uneven pressure Enduron HPGRs use a spring-loaded lateral wall which not only reduces the edge effect (maintaining a gap of as little as 1 mm) but is specifically designed to facilitate roll skew.

As shown above, an uneven feed will lead to high pressure on one side and not enough on the other. Having one roller skew will facilitate larger material at one end while ensuring the smaller particles on the other side receive enough pressure to be ground down: it maintains an even pressure distribution across the entire feed, saving energy and reducing wear, Weir says.

“The degree to which the Enduron HPGRs skew is largely dependent on the width of the roll, with longer rolls skewing about 5 mm for every metre the roll is wide. However, the effect of even small changes can be significant on local pressure peaks,” says Knapp.

“The skewing should be managed by an advanced control system, which steers the rolls to satisfy the desired output pressure. This system also ensures the skew isn’t too great or maintained for too long, which both disrupt the compressive bed.”

In the case of prolonged or excessive skewing, Enduron HPGRs send a signal notifying the supervising control system and operating staff. Prolonged skewing generally is indicative of a disturbance or fault in up-stream facilities, such as low bunker filling, upstream crusher wear, screen deck wear, or conveyor failure, Weir says.

“Where static rolls suffer from differential pressure, creating undesired product, consuming more energy and suffering additional wear, Enduron HPGRs maintain optimum pressure across the entire feed thanks to their skewing, spring-loaded lateral walls,” Weir said.

Knapp concluded: “When dealing with competent mineral feeds in real-world conditions, there’s simply no substitute for the Enduron HPGR’s ability to maximise performance with skewing.”