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Weir Minerals Africa showcases engineering nous with Cavex cyclone cluster build

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Weir Minerals Africa has manufactured a 20-way cluster of Cavex® 500 CVX hydrocyclones for a gold project in West Africa.

This hydrocyclone delivers exceptional operational efficiencies, reduced wear and consistent metallurgical performance, the OEM said. With a design built for longevity, this unit is anticipated to exceed a 20-year lifespan because of its easily replaceable wear parts that ensure peak performance throughout its service life, it added.

The hydrocyclone cluster was specifically tailored to the classification and processing requirements the project, with Lerato Ramanala, Product Manager Hydrocyclones at Weir Minerals Africa, saying it will be used in a milling application as part of a flowsheet with an HPGR and ball mill – the Cavex hydrocyclones will classify the mill discharge. Operating at a relatively low pressure of 73 kPa, the hydrocyclones are engineered to minimise equipment wear under demanding conditions, the company says.

Ramanala said: “Our design process considered factors such as port sizes and pipe schedules, ensuring obstruction-free operation, even under challenging conditions in which the hydrocyclones have to contend with a wide range of particle sizes. The feed and discharge pipes were engineered to accommodate the required flow rate and pressure, maintaining a launder geometry that ensures optimal slurry levels during regular operation, without any spillage during normal and design operation.”

The hydrocyclone cluster operates efficiently: the overflow goes to the trash screen, the underflow launder diverts the discharge, returning some to the ball mill for further grinding, while the other portion is fed to a gravity circuit.

Ramanala says the hydrocyclone cluster is custom-engineered featuring Cavex hydrocyclones, Linatex rubber linings and Isogate WR valves. The Cavex hydrocyclone features a 360⁰ laminar spiral inlet that significantly enhances separation performance, she notes.

“To prolong wear life and reduce the need for frequent replacements, we’ve used R55 rubber, a patented Weir Minerals material, in the hydrocyclones’ rubber inserts,” she adds.

To address abrasion resistance, Linatex premium rubber, known to consistently outperform other rubber materials in abrasive wet processing applications, Weir Minerals says, was selected. The integration of Linatex rubber minimises maintenance requirements and guarantees optimal equipment performance.

The Isogate WR valve is a lightweight valve designed for a hydrocyclone cluster of this size, featuring advanced rubber sleeve technology for improved wear life and full bore design for unrestricted flow, the company says.

“Notably, this is the first greenfield cluster to incorporate Synertrex IIoT technology for performance monitoring, specifically to detect any roping or splashing events,” Ramanala says. This proactive performance monitoring platform enhances the overall effectiveness of the Cavex hydrocyclones by providing accurate data on cyclone performance, supporting the operator in maintaining optimal operating conditions and enabling proactive intervention for unforeseen incidents, the company explained.

Ramanala added: “Synertrex is much more than a condition monitoring system for individual pieces of equipment. As the technology continues to develop and Weir Minerals works to leverage the equipment and process data it alone has as the OEM, its customers are increasingly seeing it as the preferred partner for intelligent solutions and digitally-enabled services.”

Even with its substantial size, a cyclone cluster of this magnitude maintains a more compact overall footprint, facilitating space optimisation within the process plant while still achieving the necessary cut point, according to the OEM.

Weir Minerals Africa says its experienced local team carefully analysed operational requirements, flow rates and pressure differentials when designing this Cavex hydrocyclone cluster to maximise efficiency and meet required throughput rates. Structural integrity was a primary focus due to the cluster’s large size, and extensive use was made of computer-aided design to ensure a robust design capable of withstanding demanding conditions. The structural design includes walkways, support beams and bracing mechanisms.

The large cluster was manufactured at Weir Minerals Africa’s facility, undergoing trial assembly and quality checks before being disassembled and packaged for shipment to the customer. Installation on site will be part of the greenfields process plant construction project, with Weir Minerals Africa specialists readily available for installation and commissioning support.

Weir Group marks Minerals and ESCO progress in H1 results

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The Weir Group has issued its half-year results to June 30, 2023, noting some significant achievements across its Minerals and ESCO divisions.

Headline numbers for the six-month period included a 19% year-on-year jump in revenues to £1.3 billion ($1.67 billion) and a 26% rise in operating profit to £212 million.

Weir Minerals continued to execute on key strategic growth initiatives, and during the first half gained market share in its core mill circuit product categories, it said.

The company said: “We converted 100% of our competitive field trials for large mill circuit pumps, and also rolled-out our latest cyclone technology.”

One highlight in the period came at a large Brazilian iron ore mine, where Weir Minerals upgraded the cyclones to its latest Cavex® 2.0 solution. The new cyclones, which are Synertrex®-enabled, have improved separation and increased mineral recovery by more than 400,000 t/y, according to the company.

Cavex 2 cyclones were launched in 2020, introducing new geometric features to offer performance unmatched by any cyclone in operation at that point, the company claimed. The advanced LIG+ design (patent pending) enables the Cavex 2 hydrocyclones to classify up to 30% more feed slurry, while occupying the same footprint as competitor hydrocyclones, according to Weir.

Weir Minerals says it also made good strategic progress in sustainable solutions during the six-month period and delivered year-on-year growth in comminution. New orders included a pebble crushing plant for a large copper mine in South America and a crushing solution for a potash mine in Canada.

The company also said it saw “very encouraging interest” from customers for its Redefined Mill Circuit, securing orders from large copper mines in South America for coarse particle flotation (CPF) pilot circuits, in partnership with Eriez.

“Through this strategic alliance, we have integrated CPF technology with our latest generation Warman® mill circuit pumps and Cavex cyclones to provide significantly improved recoveries and process efficiencies for our customers,” it said. “Once operational in the September quarter, these plants will be important reference sites for the industry.”

Around a year ago, Weir Minerals and Eriez Flotation announced a cooperative agreement to design and develop CPF systems. This allows both companies to better connect the Eriez equipment with the slurry classification and conveying expertise of Weir Minerals, according to Ricardo Garib, Division President of Weir Minerals.

Weir Minerals also launched its new, proprietary digital intelli-solutions for pumps, cyclones and high pressure grinding rolls which, coupled with its Synertrex 2.0 platform, captures critical machine health data and enables remote condition monitoring.

It concluded: “We continued to invest in research and development of our core technologies including new materials and polymers, and upgrades and range expansions for our industry leading Warman slurry pumps.”

Weir ESCO, meanwhile, reported that the number of mines using Motion Metrics™ AI-enabled vision technology increased during the first six months of the year, with new orders including a package of five ShovelMetrics™ and five LoaderMetrics™ systems to be deployed across all large mining machines at an iron ore mine in Western Australia.

“The division made excellent progress in growing market share in mining attachments, with a 37% year-on-year increase in orders,” it said. “A particular highlight included converting four cable shovel buckets from competitor products to ESCO technology for a large North American copper miner.”

The division also provided an update on trials of its proprietary ore characterisation technology, which has been leveraging the BeltMetrics™ solution from Motion Metrics positioned above a conveyor directly after the crusher in the flowsheet at an unnamed mine. As well as using the rugged vision technology Motion Metrics has previously used, the company is also incorporating hyperspectral imaging into the mix for this trial.

It reported: “Field trials of our proprietary ore characterisation technology were successfully completed during the first half. Tests enabled critical data to be collected and validated the performance of the technology in a real-world environment.”

Development has now progressed to the next phase focused on exploring “novel illumination” technologies to enhance minerals characterisation, it added.

New Motion Metrics capabilities and functions were launched during the six-month period, including an upgraded lens cleaning solution that enhances machine vision capability and improves response times.

“Other technology investments included development of a new series of mining attachments that, once launched, will expand our addressable market,” it said.

Weir Minerals expands local presence in Kazakhstan with new service ‘Supercentre’

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Weir Minerals says it has opened a new service “Supercentre” in Almaty, Kazakhstan, marking a strategically important milestone that expands local capabilities of its engineering and service expertise to accelerate customer support in the region.

The new facility includes a customer service office; a workshop for maintenance, repair and assembly of Warman® pumps, Cavex® hydrocyclones and Isogate® knife-gate valves; and a warehouse holding strategic equipment and spare parts under Vendor Managed Inventory (VMI) contracts. The 3,300 sq.m Weir Minerals Supercentre is fully equipped to perform rubber lining with premium Linatex® rubber in both cold and hot bonding, the company added.

Weir Minerals service capabilities in Kazakhstan include a complete range of services, such as installation supervision and commissioning, operational support, maintenance and troubleshooting, assistance in developing a maintenance strategy and equipment condition monitoring and analysis.

The official opening of the Supercentre was carried out by Carola Schulz, Managing Director of Weir Minerals NATCA (North Africa, Turkey and Central Asia); Gavin Dyer, Regional Managing Director of Weir Minerals ENACA (Europe and NATCA); and key customers and partners of Weir Minerals in Central Asia.

Schulz said: “Our new Supercentre in Kazakhstan will support our key customers in the region, as well as manufacture Linatex hoses and execute rubber-lining activities. This £1 million ($1.1 million) investment is core to our localisation strategy and we will continue to invest to support our ambitious growth plans in Central Asia. We have a very close strategic partnership with our customers in Kazakhstan; and we have recently been very successful with new projects in Uzbekistan. This facility will initially be supporting our customers in Uzbekistan.”

Dyer continued: “We are guided by the philosophy of supporting the local economy and always being located close to our customers. We strive to be able to contribute to our customers’ value chain and support their success; and for me the local employees are the main pillar ensuring that we are successful. It is our people that create our legacy, and we are heavily investing in the development of our employees to support our growth and the growth of our customers.”

George Sweiha, Group Procurement Director at KAZ Minerals Group, said: “From the very beginning of the mineral extraction projects at the Bozshakol and Aktogay sites, KAZ Minerals Group has been striving to ensure that original equipment manufacturers are represented in Kazakhstan to develop local capabilities; by this I mean hiring and developing local specialists and building best-in-class facilities. I am glad to see that Weir Minerals shares our vision and recognises the huge benefits of localisation for business partners, but most importantly for the country and society in which we operate.”

Weir Minerals and Andritz expand tailings processing collaboration with IsoDry

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Weir Minerals and Andritz have signed an agreement at MINExpo 2021 expanding their shared commitment and strategic cooperation to supply equipment for processing tailings in the mining industry.

The foundations of this agreement have been built on a shared understanding and vision to enable the sustainable and efficient delivery of the natural resources essential to create a better future for the world, they say.

Since 2018, Weir Minerals’ and Andritz’s partnership has seen them collaborate on joint tailings projects. This shared history as partners has reinforced their abiding belief that, together, both Weir Minerals and Andritz are stronger, they said.

This shared success has led both Weir Minerals and Andritz to renew their ongoing commitment and announce they’ll be expanding their offer to all regions around the globe.

Using Andritz’s proven separation and dewatering technologies, Weir Minerals says it has strengthened its whole-of-mine capabilities, showcasing market-leading products from extraction to comminution, mill circuit and tailings management.

“Weir Minerals has been providing tailings solutions for decades; we have dedicated research facilities – the Weir Technical Centre in Melbourne, Australia, and the Sustainable Mining Centre in Venlo, Netherlands – that are challenging conventional ways of thinking about tailings, while also developing practical, innovative and sustainable solutions that will reduce operating costs and improve safety,” Ricardo Garib, Weir Minerals Division President, said.

“Decreasing ore grades mean that mines are producing more tailings than ever before. One of the challenges with tailings management is that there cannot be a one-size-fits-all approach; each mine requires a tailored solution that carefully considers the minerals being processed, as well as the site’s climatic and geological conditions. Weir Minerals prides itself on having both the expertise and equipment that allows us to partner with miners everywhere to plan and implement tailings solutions based on their operations’ unique challenges and this agreement with Andritz enhances those capabilities,” he said.

Steve Huff, President Andritz Separation, said: “Andritz has a long history working across a range of different industries. We are very proud of the work we’ve done with Weir Minerals; together, we’re excited about continuing to provide a joint offering of sustainable and value-added tailings solutions. Both companies bring a different expertise and know-how to the partnership; we complement one another and ultimately, it’s our customers who’ll benefit.”

Tailings management forms an important element of Weir Minerals’ broader integrated solutions approach, which considers problems and challenges from all perspective and draws on a range of experts – process engineers, design engineers, product experts and materials scientists, among others – to identify potential challenges and opportunities and provide tailored solutions.

Charlie Stone, Weir Minerals VP Sales and Business Development-Mill Circuit, said: “This latest agreement enhances our overall tailings offering and enables us to provide our customers with a complete tailings solution. Under the brand name IsoDry, we will continue to offer customers a range of mechanical separation technologies, such as thickeners, filter presses, centrifuges, and vacuum belt filters.”

Weir Minerals has strengthened its tailings team to support the market and ensure that it can provide innovative solutions based on each customer’s specific requirements.

The agreement provides the opportunity for potential future collaboration on technology, harnessing Andritz’s separation technology in conjunction with Weir Minerals’ minerals and tailings processing technology. Many of these products – Warman® pumps to transport fluid tailings, GEHO® pumps to handle paste, Cavex® hydrocyclones to dewater tailings and the Multiflo® range of dewatering solutions – have been integral to helping miners manage their waste for generations, they said.

Weir Minerals and Andritz have also reiterated their shared commitment to sustainability; it is an essential part of both their business and corporate strategies. Both companies say they have outlined ambitious plans to reduce their carbon emissions, while their approach to ESG initiatives extends to all aspects of their organisations.

Weir adds aftermarket and service contract to Iron Bridge remit

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The Weir Group says it has won a £95 million ($127 million) order to provide aftermarket components and service to the Iron Bridge magnetite project in Western Australia.

The aftermarket contract follows Weir’s success in winning a record £100 million order for original equipment for the Iron Bridge project in 2019, including its Enduron® High Pressure Grinding Rolls (HPGRs, pictured) that, it says, will enable dry processing of ore and use at least 30% less energy than traditional alternatives.

The Iron Bridge magnetite project is a $2.6 billion joint venture between Fortescue Metals Group’s subsidiary FMG Magnetite Pty Ltd and Formosa Steel IB Pty Ltd located in the Pilbara region, around 145 km south of Port Hedland.

Both the aftermarket order and revenues will be recognised over the seven-year period of the agreement, which starts in 2022, in line with the 22 Mt/y project’s initial production.

Ricardo Garib, President of Weir Minerals, said: “This is another landmark order for Weir. Having helped design an energy and water efficient magnetite processing plant, we are delighted to provide operational support for Iron Bridge from 2022. It is an excellent example of the value that Weir’s innovative engineering and close customer support can create for all our stakeholders and reflects the key role we have to play in making mining operations more sustainable and efficient.”

Weir’s Enduron HPGRs are increasingly replacing conventional mills in comminution circuits, Weir says. In addition to their energy and water savings, they also reduce grinding media consumption, while their wearable components last longer, reducing maintenance costs. Additionally, HPGRs contribute significantly to carbon dioxide emission savings.

Stuart Hayton, Managing Director of Weir Minerals Netherlands, where the Enduron HPGRs are designed and manufactured, said: “This is an important project for Weir and for the broader mining industry. We know comminution is one of the most energy intensive parts of the mineral process and, with our Enduron HPGRs, we have a unique ability to offer significant cost, energy and water savings to customers around the world. As the mining industry evolves, we are commited to continuing to innovate, reducing miners’ costs and environmental impact.”

This latest contract award means Weir now has more than £200 million of orders from the Iron Bridge project including its Enduron HPGRs, GEHO® and Warman® pumps, Cavex® hydrocyclones and Isogate® valves.

To support the project and future growth, Weir says it will build a new service centre in Port Hedland, Western Australia, thereby providing employment and training opportunities in the area, with a particular emphasis on supporting greater Aboriginal representation in the broader mining workforce.

New Weir Minerals Sand Wash Plant to boost recoveries

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Weir Minerals has released a complete sand wash solution that draws on its long experience in the sand and aggregate industry.

The Weir Minerals Sand Wash Plant comes with Linatex® lining, produces more saleable product than conventional sand screw plants, with fewer moving parts, and has an optimised process that produces a drier, higher-quality product with less fines, according to the company.

The solution has already proven effective at sites like Coimbatore Minerals in Tamil Nadu, India, Weir says, where a custom-built wash plant reduced its total cost of ownership by 51%, while offering a 23% reduction in fines that helped the company consistently meet the industry’s high standards for a saleable product.

Bruce Cooke, Global Product Manager – Sand Wash Plants for Weir, said: “We know the most important thing for quarry operators in washing is recovering as much sand as possible to maximise their sales, which is why we’ve designed an integrated solution for washing their product, with a hydrocyclone which can deliver greater recovery than sand screws. In addition, every component has been selected by our expert engineers for its long-service life, interoperability and ease of maintenance.”

The compact solution features a range of Weir Minerals equipment designed for high efficiency in sand and aggregate applications, including Warman® WGR pumps, Cavex® hydrocyclones, Enduron® dewatering screens, Linatex hoses and Isogate® knife gate valves.

The Warman WGR is a popular pump in the sand extraction industry, according to Weir, combining top of the line hydraulic design with an adjustable impeller, long bearing life and a simplified wet end, making replacement predictable and cost effective.

Precision moulded and lined, Linatex premium rubber is used for wear zones throughout the plant due to its proven wear performance in wet sand applications in operations around the world, Weir said.

Cavex hydrocyclones provide “exceptional classification efficiency” thanks to their unique 360° laminar spiral, delivering more saleable product than a sand screw solution would, the company said. Enduron dewatering screens, meanwhile, reliably separate product with a high degree of efficiency. And, finally, Isogate knife gate valves contribute to the plant’s straightforward maintenance.

Surendra Menon, President, Weir Minerals India, said: “For the new sand wash plant, we focused on making it quick and easy for quarry operators to get up and running. Its straightforward design means it can be assembled in just two days while its compact skids make it easy to drag into any operation.

“Efficient, reliable and easily integrated into flowsheets, we think the plant is a game changer for quarry owners.”

Weir Cavex hydrocyclones take a load off at OceanaGold Didipio mine

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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.

MATSA wins quick payback from Weir Cavex hydrocylone installation

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Weir Minerals says the introduction of a Cavex® hydrocyclone cluster at MATSA’s processing plant, in Spain, has delivered payback in just three days.

MATSA is a modern Spanish mining company based in the north of the Iberian Pyrite Belt, a mining district that has been active for more than 2,500 years. The company, owned 50:50 by Trafigura and Mubadala Investment Company, owns and operates three mines in the province of Huelva, Spain: Aguas Teñidas and Magdalena, located in Almonaster la Real, and the Sotiel mine, in Calañas.

The processing plant, in Almonaster, recently went through a €236 million ($266 million) expansion that saw capacity go from 2.2 Mt/y to 4.4-4.7 Mt/y through the addition of a second plant. The plant now has the capacity to treat copper and polymetallic ores through three grinding lines.

Weir Minerals says it has been working with MATSA to optimise its minerals treatment plant’s primary and secondary grinding circuits.

Seda Kahraman, Regional Process Engineer Manager for Weir Minerals, said: “We have been working with MATSA for 12 years and our service team has built a solid partnership with them. We opened a service site close to MATSA and employed a full-time Service Engineer on site to provide adequate support.

“Their success is our success, and working on this particular project was both very challenging and very rewarding. They needed to increase their grinding circuit capacity from 275 t/h to 307 t/h, whilst reducing the quantity of ultrafines in the final overflow of the second hydrocyclone cluster.”

Antonio Gamiz, MATSA Plant Technical Director, said: “To maximise our plant productivity we needed a Cavex hydrocyclone cluster that was specifically designed to our application. This was achieved without an extension of the plant area and with minimal capital expenditure.”

Weir Minerals took a holistic approach to this challenge by first creating a simulation of the entire primary and secondary grinding circuit. This enabled it to visualise how the process should be running, and the most appropriate way to deliver this.

Following the simulation, the best operating conditions were calculated to support the required capacity increase and elimination of slimes, Weir said. This included the ball mills, mill liners and hydrocyclones. Using 3D laser scanner technology, the team at Weir Minerals developed a suitable layout for the equipment, including modification and steel structures.

Kahraman said:“This truly was a turnkey solution; the team had to pull together all their smarts, capabilities and tools to ensure MATSA’s grinding capacity was raised, whilst simultaneously reducing the quantity of ultrafines from their overflow. We achieved this with a range of tools and techniques including engineer design, subcontract management, and manufacturing of steel.”

To deliver the solutions MATSA required, Weir Minerals replaced the primary hydrocyclone cluster, as well as the spare parts on the secondary hydrocyclone cluster; redesigned the steel structure and walkways; installed new hydrocyclone feed pumps and piping configurations, installing and commissioning the entire project, Weir said.

The modification to the steelwork and piping, as well as the assembly of the new three-way Cavex 650CVX hydrocyclone cluster were completed in less than four days without any production interruptions, according to Weir.

Upon analysing samples from various points in the grinding circuit, it was confirmed the feed capacity had successfully increased to 300-307 t/h.

Kahraman said: “In addition to the desired increase in grinding capacity, we also improved circulating load in the primary ball mill and restored the feed pressure to the Cavex hydrocyclones to 85 kPa. We are thrilled that MATSA achieved payback in just three days due to the increase in production by 500 t/d, and achieved additional revenue of €2,751/h.”

Weir Minerals Africa on the Cavex CVXT hydrocyclone

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Weir Minerals Africa says its locally-manufactured Cavex® CVXT tile lined hydrocyclone features unique laminar spiral inlet geometry designed to deliver sharper separation, maximum capacity and longer wear life.

The CVXT tile lined hydrocyclones are available in a large range of sizes to process any feed tonnage requirement, the company said. All components are designed for ease of maintenance and efficient operation, it added.

“This innovative design provides a natural flow path into the cyclone body, allowing the feed stream to blend smoothly with the rotating slurry inside the chamber,” Weir said. The result is greatly reduced turbulence through the whole cyclone, dramatically improving the separation efficiency of the hydrocyclone, according to the company. It is also offers a much longer wear life than conventional involute and tangential feed inlet designs, the company added.

The Cavex® CVXT hydrocyclone can be fitted with an extended barrel which, again, increases efficiency by increasing the residence time in the hydrocyclone. This is especially for use with ores carrying a high content of near-density materials. The hydrocyclone is also available with different overflow configuration options to suit operational needs.

To maintain separate efficiency at different operating yields and spigot sizes, a wide range of vortex finder sizes ranging from 0.4 to 0.5 are available. “These are designed to maintain a strong air-core at the different sizes. The spigot sizes range from normal to extra high capacity to accommodate low yield ores. These can also be manufactured in different material to prolong the hydrocyclone life and efficiency,” Weir said.

Weir Cavex hydrocyclones prove their worth at South Africa diamond mine

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Weir Minerals’ Cavex® hydrocyclones have been put to the test at a diamond mine in South Africa’s Northern Cape Province, proving the technology can be applied in dense medium separation (DMS) plants treating diamondiferous material, according to the company.

In her presentation to the Southern African Institute of Mining and Metallurgy (SAIMM) diamond conference in Johannesburg in 2018, Weir Minerals Africa’s Senior Process Engineer, Boitumelo Zimba, said the hydrocyclones improved plant efficiency and produced 40% more tonnage than the mine’s target.

“As the Cavex hydrocyclone is tried and tested in hard-rock mining and coal classification, the Cavex 360° laminar spiral inlet profile was used as a basis for the development of a dense medium cyclone,” Zimba said. “Individual casting patterns were developed and produced in order to fabricate the Cavex dense medium hard chrome cyclone with the exact laminar spiral feed chamber that exists when moulded out of rubber.”

The customer required a solution that could offer at least six months wear-life, and a probable error of separation (Ep) of no greater than 0.08 at a cut density of 3.1 t/m³. Tracer tests were used to monitor the efficiency of the separation achieved by the Cavex hydrocyclones to ensure all of these requirements were met.

“Ep values achieved were 0.042 for the 4 mm tracer tests and 0.035 for the 8 mm tracer tests, which were below the set maximum target of 0.08 from the mine,” Zimba said. “This highlighted the benefits and improved efficiencies of the Cavex laminar spiral feed inlet.”

The lower the Ep – or probable error of separation – the more efficient the separation; it is defined as half the difference between the density at which 75% is recovered to sinks, and that at which 25% is recovered to sinks, Weir said.

“The customer’s tracer tests on the Cavex hydrocyclones showed that cut points of 3.08 t/m³ were achieved for both the 4 mm and 8 mm tracers,” Zimba said. “This was within the performance levels of 3.1 t/m³ that the customer had specified.”

Initially, the hydrocyclones were commissioned to treat only fines at the diamond plant – the minus 8+1 mm material. Later however, the mine decided to run a combined DMS, after which the full DMS size range of minus 20+1 mm was treated through all the fines DMS hydrocyclones.

“The unique design of the laminar spiral inlet geometry delivers sharper separation and maximises capacity while delivering a longer wear-life than conventional involute or tangential feed inlet designs,” Weir says. “By providing a natural flow path into the hydrocyclone body the design allows the feed stream to blend smoothly with the rotating slurry inside the chamber, reducing turbulence and improving separation efficiency.”

Zimba explained: “Combining our cone and spigot components in the hard metal range is an important contribution to the reduction in turbulence. Another vital factor is the Cavex inlet design with 360° scroll; this design was proven through extensive computational fluid dynamics analysis as well as our multiple installations to date.”

Weir Minerals also conducts ongoing research and development on methods to minimise turbulence on assembled casted components. The Cavex hydrocyclones are designed with a variety of inlet sizes to accommodate a wide top size at specified medium-to-ore ratios. The inlet sizes range from 0.2 to 0.33 as a function of the hydrocyclone diameter.

“The Cavex CVX hydrocyclone also has a wide range of vortex finder sizes to maintain separation efficiency at different operating yields and spigot sizes. The vortex finder sizes range from 0.4 to 0.5 as a function of cyclone diameter, and are designed to maintain a strong air-core at different spigot sizes,” Weir says.

To prolong life and efficiency, the hydrocyclones can also be manufactured with different materials.

“Cavex CVXA hydrocyclones are hard-wearing and are cast in 27% chromium iron for maximum abrasion resistance; components are designed for ease of maintenance, with all surfaces joined with a layer of epoxy cement,” the company says.

Weir Minerals Africa operates two foundries in South Africa – one at its Isando facility and the other at its Heavy Bay Foundry in Port Elizabeth. “This allows the organisation to cast items in-house leveraging its local foundry personnel’s knowledge, experience and expertise, ensuring that the highest standards are maintained,” Weir says.

“This approach ensures optimal life of the hydrocyclone in operation, and reduced maintenance costs by replacing worn parts in situ. It also eliminates the risk of any adverse effects on performance arising from mixing old and new hydrocyclone components. Further, safety on site is enhanced by minimising the maintenance work necessary on the installed hydrocyclones.”

Zimba said future work will include the investigation of various alloys to combat high wear rates on some of the hydrocyclone components, in particular the vortex finder and the cone sections. “This will allow longer operation and plant stability,” she said.