Tag Archives: screens

FLSmidth improves water balance at Mozambique coal plant with thickener tech

FLSmidth has been chosen as the preferred provider for four large bolted thickeners for a large mining customer in Mozambique.

Two of the thickeners are designed to reduce water load on the filters allowing for a drier filter product, while the other two thickeners recover water from the plant tailings.

The installation, which includes E-Volute™ feedwell technology for superior flow distribution, will contribute to achieving optimal water balance at the coal plant in Mozambique, FLSmidth says.

“The thickeners measure 45 m in diameter and will control the density of material to the belt filters, improving the plant’s output,” Howard Areington, FLSmidth’s General Manager for Projects and Account Sales in sub-Saharan Africa and the Middle East, says. “The design was based on the test work we conducted on the customer’s material, allowing us to determine the best thickener solution.”

He emphasised that a bolted thickener is quicker and safer to construct on site, saving on costs and improving quality control; both of these factors suited the project’s remote location.

“The extent of welding in the construction of normal steel thickeners typically runs into kilometres,” Areington said. “By contrast, the amount of on-site welding required by a bolted thickener can be measured in metres.”

The E-Volute feedwell technology improves flow distribution, leading to lower flocculant consumption, better settling rates and improved overflow clarity for the optimal performance of the thickener, according to FLSmidth.

Despite the COVID-19 lockdown, good progress was made on the fabrication of the thickeners in South Africa, according to FLSmidth Project Manager, Kevin Kockott. This has been managed by leveraging FLSmidth’s global resources and the design teams’ ability to work remotely.

“Our local South African office collaborated closely with our engineering hub in Salt Lake City in the United States, ensuring that our engineering work on the project was able to continue without interruption,” Kockott said.

FLSmidth has been involved with this project for almost a decade and has provided a significant portion of the coal preparation equipment. To date, this has included reflux classifier technology, pumps, screens and feeders.

Weir Minerals wins large comminution order from Nigeria iron ore mine

Two of the largest screens built by Weir Minerals Africa are being designed and manufactured in South Africa as part of a process solution for an iron ore mine in Nigeria.

According to Tiisetso Masekwameng, General Manager Comminution at Weir Minerals Africa, the flowsheet accepted by the customer includes equipment for screening, washing, and grinding supplied by Weir Minerals.

“Within our scope of work are the two largest Enduron® double-deck banana screens built by Weir Minerals,” Masekwameng says. “This is made possible by the depth of design expertise in our Separation Technology Group, an eight-strong team conducting research and development.”

Steven Hunter, Separation Technology Group Leader at Weir Minerals Africa, says the two 51 t Enduron double-deck banana (DBHG 43/97) screens (one pictured) for this project were built upon the designs of the existing Weir Minerals screens range. These large machines measure 4.3 m wide and 9.7 m long and can process 1,750 t/h.

“The customer’s production requirements demanded this considerable size, so we optimised the design by minimising mass without compromising structural integrity,” Hunter says. “We conducted extensive finite element analysis on the whole machine but focused on the main structural elements, ensuring that the units were fit-for-purpose while still being light enough to be driven by the exciters.”

The size of the units still demanded the design and manufacture of Weir Minerals Africa’s largest exciter yet – the Enduron LTX 10. With 120 t of excitation force (at maximum setting), these units will drive the screens at a stroke of 9.4 mm and a gravitational force of 4.6 G.

Hunter said the screens are ready to be fitted with Weir’s IIoT platform, Synertrex. “This allows the machines to be monitored remotely; the system can measure the machine’s performance and any deviations arising that may require proactive attention,” he explained.

The order for Nigeria also includes two Trio® jaw crushers, two Trio cone crushers, two large 2 m by 8 m Trio apron feeders, two Trio pan feeders, eight Enduron vibrating screens and an Enduron HPGR.

For the clay washing circuit, Weir Minerals Africa will supply the mine with a Trio twin-shaft blade mill and Trio twin-shaft coarse washers as well as Warman® slurry pumps.

Kwatani branching out from South Africa roots

Vibrating screen and feeder specialist Kwatani says it is transitioning from equipment supplier to solutions provider, as it attracts customers from well beyond its South Africa headquarters.

According to Kwatani General Manager Sales and Service, Jan Schoepflin, the company’s strong in-house expertise and design capability – combined with the manufacturing quality it consistently achieves – ensures its customised solutions deliver optimal performance at the lowest possible lifecycle costs.

“Our recent orders show that our customer base in Southern Africa remains strong, while there is growing recognition of our cost-effective offerings in West Africa, East Africa and North Africa,” says Schoepflin. “At the same time, orders from countries like Canada and Russia indicate that our markets abroad continue to grow.”

Kwatani says it remains the market leader in the supply and servicing of vibrating screens and feeders on iron ore and manganese mines in South Africa’s Northern Cape province. It also counts platinum, coal, diamond and gold mines in its customer base. Its West Africa orders have been mainly to gold mines, and there is growing potential for gold mining in East Africa, Schoepflin says.

Over its four decades of operation, Kwatani has produced about 16,000 custom-designed screens, and is building, on average, 30 to 40 units a month in its ISO 9001:2015 certified facility close to OR Tambo International Airport in Johannesburg.

“Our reputation has been built on prioritising what our customers need, and doing business with integrity and trust,” Schoepflin says. “This means delivering on what we promise and making sure that customers achieve the expected value from our products.”

The company’s solution focus is underpinned by its significant and ongoing investment in local skills, ensuring that its designs leverage strong mechanical and metallurgical engineering expertise, according to Schoepflin.

“This confidence in our products allows us to offer a process guarantee to customers, to deliver the tonnage, throughput and fractions that they expect,” he says. “Depending on which country our customers operate in, they may also have different industry and quality standards/certification expectations and we work closely with them to understand these clearly and meet their requirements.”

Schoepflin also emphasises the company’s service capabilities, which include its local service centres closer to customers, and its support partners in other countries.

“The careful selection of these partners is vital to meet customers’ stringent technical expectations,” Schoepflin says. “In some countries, our partners can also manufacture components according to our drawings and specifications, should there be an urgent requirement from a customer.”

Kwatani collaborating with EPCMs, miners on bespoke screening options

Mineral process plant designs are favouring higher-capacity vibrating screens and a more holistic approach to plant optimisation, according to screen specialist Kwatani.

“These trends hold great potential for the mining sector, and Kwatani has been at the forefront of technologies driving this direction,” Annelize van der Walt, Kwatani’s Business Development Manager for Mining and Minerals, says.

Vibrating screens are essentially the “glue” that integrates various unit processes, from bulk materials handling to optimally liberated comminution and pre-concentration, according to the company.

“Larger, engineered-for-tonnage screens are growing in popularity, as they reduce the number of processing modules and hence the level of infrastructure required, especially on mega-projects,” van der Walt says. “Higher capacity is becoming the new design standard for greenfields projects.”

There is also an ever-greater demand for reliability and uptime in these mission-critical machines, as well as an expectation of longer lifespans. All this requires bespoke solutions that address site-specific conditions, van der Walt says, while leveraging digital technology for real-time monitoring and control.

“Kwatani’s metallurgists and engineers use their extensive on-site experience and in-house laboratory facilities to innovate from our proven technologies,” she says. “A cornerstone of our philosophy is close collaboration with engineering, procurement and construction management contractors and end-customers to customise solutions, from concept to construction, commissioning and operation.”

Annelize van der Walt, Kwatani’s Business Development Manager for Mining and Minerals

Specific conditions include waterless beneficiation in arid Mauritania, where Kwatani’s screens operate completely dry in an iron ore plant. In South Africa and Botswana, meanwhile, the company has retrofitted dewatering screens to reduce water consumption, while increasing output by 40% with the same footprint.

“We also recently designed screens for exceptional ore characteristics in a precious metal beneficiation facility in Canada,” she said. “This required a high level of customisation, not only in the screening media but in the mechanical design.”

Remote mine locations – which are difficult to access for maintenance and replacement purposes – also guide the design parameters. In a recent project, Kwatani innovated by selecting special hard-wearing materials for the construction of the screening equipment. The design included components that would provide early warning of wear.

Embracing a more holistic plant design approach, customers often invite Kwatani to participate in optimising the screening side of their chosen beneficiation technology, van der Walt says. A different screening approach would be taken, for instance, in a dry pre-concentration application than in wet dense medium separation.

“This holistic approach is also facilitating greater synergy between original equipment manufacturers,” she says. “This is a very positive trend, allowing us to consider the impact of different equipment on the performance of each – from mineral processing apparatus to transfer chutes.”

Underpinning Kwatani’s responsiveness to customer’s specific needs is its ongoing research and development.

“Our R&D unit is currently working on projects to suit our designs to novel crushing and grinding technologies, which are changing the whole approach to the process flow of future plants,” van der Walt says. “These are significant innovations for the mining sector, and we are excited to be at the forefront with our evolving screen designs.”

Kwatani is incorporating digital technologies to facilitate remote monitoring and control of its vibrating screens. It is also piloting a service app for mobile phones, which helps operations predict their maintenance needs more accurately. The app also helps to drive down the total cost of ownership by gathering data that can be used in future design improvements.

Latest Kamoa-Kakula copper studies reaffirm project’s world-class status

The latest economic studies on Ivanhoe Mines and Zijin Mining Group’s majority-owned Kamoa-Kakula project in the Democratic Republic of Congo have indicated the asset could become the world’s second largest copper mining complex.

First production at Kamoa-Kakula is less than a year away, but the project partners have continued with a series of economic studies that emphasise the world-class nature of the orebodies within their control.

The headline maker is the results of a preliminary economic assessment that has evaluated an integrated, multi-staged development to achieve a 19 Mt/y production rate at the mine, with peak annual copper production of more than 800,000 t.

At the same time, a prefeasibility study (PFS) has been carried out to look at mining 1.6 Mt/y from the Kansoko mine, in addition to 6 Mt/y already planned to be mined from Kakula, to fill a 7.6 Mt/y processing plant at Kakula.

A definitive feasibility study (DFS) has also evaluated the stage-one, 6 Mt/y plan at Kakula, which is currently being constructed and is less than a year away from producing first copper, according to Ivanhoe Co-Chair, Robert Friedland.

While the operation looks to have the scale of a world-class asset, it will also have top ranking ‘green’ credentials, according to Friedland.

“The Kakula mine has been designed to produce the world’s most environmentally-responsible copper, which is crucial for today’s new generation of environmentally- and socially-focused investors,” he said.

“Zijin shares our commitment to build the new mines at Kamoa-Kakula to industry-leading standards in terms of resource efficiency, water and energy usage, and minimising emissions. We are blessed with ultra-high copper grades in thick, shallow and flat-lying orebodies – allowing for large-scale, highly-productive, mechanised underground mining operations; and access to abundant clean, sustainable hydro electricity to power our mines – providing us with a distinct advantage in our goal to become the world’s ‘greenest’ copper miner and be among the world’s lowest greenhouse gas emitters per unit of copper produced.”

The project recently retained Hatch of Mississauga, Canada, to independently audit the greenhouse gas intensity metrics for the copper that will be produced at Kamoa-Kakula.

The Kamoa-Kakula Integrated Development Plan (IDP) 2020, as the companies refer to it, builds on the results of the previous studies announced in February 2019.

DFS to 6 Mt/y

The new DFS incorporates the advancement of development and construction activities to date, and has once again confirmed the outstanding economics of the first phase Kakula Mine, Ivanhoe said.

It evaluates the development of a stage one, 6 Mtpa underground mine and surface processing complex at the Kakula deposit with a capacity of 7.6 Mt/y, built in two modules of 3.8 Mt/y, with the first already under advanced construction (see photo). It comes with an internal rate of return of 77% and project payback period of 2.3 years.

The first module of 3.8 Mt/y commences production in the September quarter of 2021, and the second in the March quarter of 2023. The life-of-mine production scenario provides for 110 Mt to be mined at an average grade of 5.22% Cu, producing 8.5 Mt of high-grade copper concentrate.

The Kakula 2020 DFS mine access is via twin declines on the north side and a single decline on the south side of the deposit. One of the north declines will serve as the primary mine access, while the other decline is for the conveyor haulage system, which was recently commissioned.

The primary ore handling system will include a perimeter conveyor system connected to truck load-out points along the north side of the deposit. The perimeter conveyor system will terminate at the main conveyor decline.

The mining method for the Kakula deposit is primarily drift-and-fill using paste backfill (around 99%); with the exception of a room-and-pillar area close to the north declines, which will be mined in the early years of production. The paste backfill system will use a paste plant located on surface connected to a distribution system that includes a surface pipe network connected to bore holes located at each connection drive on the north side of the orebody, the company says.

The Kakula concentrator design incorporates a run-of-mine stockpile, followed by primary cone crushers operating in closed circuit with vibrating screens to produce 100% passing 50 mm material that is stockpiled.

At the end of August, the project’s pre-production surface ore stockpiles totalled an estimated 671,000 t grading 3.36% Cu, including 116,000 t of high-grade ore grading 6.08% Cu.

The crushed ore is fed to the high pressure grinding rolls operating in closed circuit with wet screening, at a product size of 80% (P80) passing 4.5 mm, which is gravity fed to the milling circuit.

The milling circuit incorporates two stages of ball milling in series in closed circuit with cyclone clusters for further size reduction and classification to a target grind size of 80% passing 53 micrometres (µm).

The milled slurry is pumped to the rougher and scavenger flotation circuit where the high-grade, or fast-floating rougher concentrate, and medium-grade, or slow-floating scavenger concentrate, are separated for further upgrading. The rougher concentrate is upgraded in the low entrainment high-grade cleaner stage to produce a high-grade concentrate.

The medium-grade or scavenger concentrate together with the tailings from the high-grade cleaner stage and the recycled scavenger recleaner tailings are combined and further upgraded in the scavenger cleaner circuit. The concentrate produced from the scavenger cleaner circuit, representing roughly 12% of the mill feed, is re-ground to a P80 of 10 µm prior to final cleaning in the low entrainment scavenger recleaner stage.

The scavenger recleaner concentrate is then combined with the high-grade cleaner concentrate to form final concentrate. The final concentrate is then thickened and pumped to the concentrate filter. Final filtered concentrate is then bagged for shipment to market.

The scavenger tailings and scavenger cleaner tailings are combined and thickened prior to being pumped to the backfill plant and/or to the tailings storage facility. Backfill will use approximately half of the tailings, with the remaining amount pumped to the tailings storage facility.

Based on extensive test work, the concentrator is expected to achieve an overall recovery of 85%, producing a very high-grade concentrate grading 57% copper. Kakula also benefits from having very low deleterious elements, including arsenic levels of 0.02%.

7.6 Mt/y PFS

The PFS evaluating mining 1.6 Mt/y from the Kansoko mine envisages an average annual production rate of 331,000 t of copper at a total cash cost of $1.23/lb copper for the first 10 years of operations, and annual copper production of up to 427,000 t by year four. This comes with an internal rate of return of 69% and project payback period of 2.5 years, according to Ivanhoe.

Development would see Kakula-Kansoko benefit from an ultra-high, average feed grade of 6.2% Cu over the first five years of operations, and 4.5% Cu on average over a 37-year mine life.

There are currently two mining crews at Kansoko, in addition to the 10 mining crews (three owner crews and seven contractor crews) currently at Kakula, with the ability to increase this number to fast-track the development of Kansoko, Ivanhoe said.

19 Mt/y option

The Kamoa-Kakula 2020 PEA presents initial production from Kakula at a rate of 6 Mt/y, followed by subsequent, separate underground mining operations at the nearby Kansoko, Kakula West and Kamoa North mines, along with the construction of a 1 Mt/y of concentrate direct-to-blister smelter. The smelter section of the study saw China Nerin Engineering act as the main engineering consultant with Outotec providing design and costing for propriety equipment.

The Kamoa North Area comprises five separate mines that will be developed as resources are mined out elsewhere to maintain the production rate at up to 19 Mt/y, with an overall life in excess of 40 years, Ivanhoe says.

For this integrated 19 Mt/y option, the PEA envisages $700 million in remaining initial capital costs, with future expansion at Kansoko, Kakula West and Kamoa North funded by cash flows from the Kakula mine, resulting in an internal rate of return of 56.2% and a payback period of 3.6 years.

This shows the potential for average annual production of 501,000 t of copper at a total cash cost of $1.07/lb copper during the first 10 years of operations and production of 805,000 t/y of copper by year eight, Ivanhoe said.

“At this future production rate, Kamoa-Kakula would rank as the world’s second largest copper mine,” the company said.

Kwatani screens and feeders tackle manganese ore in South Africa

As a vital aspect of a plant expansion at a manganese mine in the Northern Cape of South Africa, Kwatani says it is supplying four heavy duty vibrating screens and 10 feeders to help boost throughput.

According to Kwatani CEO, Kim Schoepflin, this large-scale equipment is custom-designed and engineered for tonnage to meet the mine’s challenging operational requirements.

“Manganese ore is very demanding on vibrating screens as it has a high specific gravity and is also very abrasive,” Schoepflin says. “Our machines are engineered to perform the application’s duty requirement while being robust enough to deliver maximum uptime.”

The units being supplied include a 3.6 m double-deck scalping screen, a 3 m double-deck screen, a 2.4 m screen and a 1.8 m dewatering screen. A local OEM that has designed and engineered vibrating screens for over four decades, Kwatani has built a reputation for world-class expertise and capability, it says.

“Customers choose us for our engineering track record – developing technology that can manage the tonnages they require,” Schoepflin says. “This means understanding each mine’s specific conditions, and then building a design to meet a range of complex mechanical and metallurgical factors.”

The order to the mine is being rolled out on time and on specification to the customer’s satisfaction, according to Kwatani COO, Kenny Mayhew-Ridgers.

“The efficiency and quality of our work process allows us to design, manufacture and deliver custom-designed screens in the same timeframes that other OEMs deliver standard models,” Mayhew-Ridgers said.

This is particularly demanding as custom-designed equipment undergo an intensive design process after being verified by rigorous finite element analysis in-house, Kwatani says. Prior to dispatch, all units endure intensive testing before being commissioned on a customer’s site. For this reason, Kwatani boasts its own in-house advanced testing facilities at its Kempton Park facility, in South Africa. Aligned to ISO 9001 standards, the testing protocols have been developed in-house with decades of experience. This allows full testing similar to cold commissioning, even before delivery to site.

Weba Chute Systems and Kwatani save the day at South Africa gold mine

Weba Chute Systems and Kwatani have come together to design and install ore silo chutes at a South Africa gold mine to reduce mill wear and other processing challenges caused by the uncontrolled flow of mined material into the mills.

The solution from Weba and Kwatani, a leading local manufacture of vibrating screens and feeders, must also deal with frequent large-size material as the mine has no crushing stage before the milling circuit, Weba said.

According to Weba Chute Systems Technical Advisor, Alec Bond, the over-feeding of material through the existing manually operated chutes is causing regular “mill vomit” in the mine’s four mills. The inconsistent feed exacerbates wear on mill bearings as the material’s weight shifts forwards and backwards inside the mill.

The waves of material causing the “vomit” carry insufficiently milled material out of the mill, including large chunks of rock. This leads to problems for the downstream mineral processing facilities, including inefficient recovery in flotation cells and even blockages in pumps, according to Bond.

“The challenge starts with the existing chutes needing constant supervision and control by operators, being opened and closed with a chain block device,” he says. “Our solution was to design a robust, self-controlling chute and feeder system that would ensure an even flow of material into the mills.”

He explained that the mine’s existing system has no means of closing the silo outlet; any maintenance at the chute area requires the emptying of the silo and the stoppage of the mill. Each of the four silos has three outlet chutes.

Weba Chute Systems Designer, Wesley Hunkin, says: “We therefore added a spile bar arrangement which seals off the silo. The Weba chute, which is choke fed, is placed under this installation. This allows the feed rate to be controlled by the Kwatani feeder, which has been integrated into the chute design.”

The vibrating action of the feeder controls the tonnage and feed rate to the mill, keeping the flow constant. New mounting structures have been designed to accommodate each chute and feeder. There will also be civils works below the silo to provide a solid foundation that absorbs vibrations from the feeder, according to the companies.

A serious challenge is over-sized rocks in the ore feed, which can be up to 800 mm in size. This makes it important for chute designs to accommodate the worst-case scenario of chutes choking, says Hunkin.

He highlighted that the flow of material is also controlled to prevent direct impact onto the conveyor belt feeding the mills, and to ensure central loading onto the centre of the belt.

“If the material from the feeder is biased to the one side, our chute brings everything to the centre of the conveyor,” he says. “This enhances the consistency of material flow into the mill.”

Bond emphasised that the customer motivated for a concept change to address the challenges being experienced with the silo feed.

“Given our materials handling experience, design expertise and high-quality local manufacturing facility, we were able to work closely with the customer and with Kwatani to turn this new concept into reality,” he said.

“Our solution promises direct savings in terms of mill bearings, as well as less mill downtime. There will also be significant gains in terms of recovery rates in the plant if the flow and size of milled material can be improved.”

Schenck displays continental comminution offering with Peru copper contract

Schenck Process has won a contract to design manufacture, supply and commission vibrating screens and feeders for the greenfield Mina Justa copper project, in Peru.

The order will see Schenck business units on four continents combine to deliver seven banana screens (across three models), five diverging pan feeders and one grizzly feeder.

Mina Justa, owned by Minsur and Empresas Copec through holding company Cumbres Andinas, is slated to produce around 100,000 t/y of copper when fully ramped up.

The screens and feeder contract will see all design completed at Schenck’s vibrating equipment design centre in Sydney, Australia, manufacture and testing in the company’s Chinese plant, custom-made screen panels from the South Africa production facility and commissioning by the aftermarket services team in Chile. The project is being managed and coordinated by the Australia-based Project Management team, Schenck said.

The screens include several mechanical and operational improvements developed on a prototype vibrating screen now undergoing site testing at an iron ore mine in Western Australia, according to the company.

“The five larger screens feature laminated side plates to maintain structural integrity and reduce stress concentrations associated with the projected process tonnages,” Schenck explained. “Additionally, machined transition flanges are welded in a low stress area to the cross beams to actively reduce fatigue, and a unique spring removal system has been fitted to facilitate and reduce downtime during spring change-outs.”

The six feeders have been designed to account for site conditions and feature a more robust design. They are also equipped with exchangeable liners and an upgraded transition hopper to improve operational availability and performance, the company said.

Each of the vibrating feeders and screens for Mina Justa is equipped with CONiQ, the company’s proprietary continuous six-dimension condition monitoring system, to track and alert operators to abnormal operating conditions. Feeder control systems have been electronically aligned with the screen’s installation, Schenck added.

Project manager, Lauren Williams, said: “This is a truly international project and, from our point of view, it is the best way to give our customer the equipment that will deliver higher process efficiency and longer service life.

“Although based on standardised platform designs for screens and feeders, each unit has been subject to a customising process to meet site and processing capacity requirements. We are delivering an integrated package of screens and feeders to optimise availability and productivity and represent the best value for money.”

Multotec ready for the mineral processing test

Mineral processing specialist, Multotec used a recent media visit to talk up the testing facilities at the heart of its Technology Division.

The South Africa-based company can carry out a range of testwork with its specialised equipment in Spartan, Gauteng, according to Multotec Technology Manager, Faan Bornman.

“Much of our testwork comes from customers who are in the early stages of project development,” Bornman says.

“They need to understand more about how their minerals or material will separate under given conditions. Often there is not a mathematical model that can predict accurately what they can expect.”

Testwork can reduce project risk significantly, providing a solid foundation for the subsequent design and optimisation of process facilities, Multotec says, with Bornman noting that physical testwork is usually the best way of finding out how particles will behave in a process plant.

The equipment available to Multotec customers includes laboratory-scale wet high-intensity magnetic separators, cyclone rigs, filtration equipment, centrifuges, spiral rigs and a screening research rig. There is even capacity to test water purification methods on mine effluent.

“Extensive test work is especially relevant when a customer is wanting to mine and treat less traditional minerals like lithium or graphite,” Bornman says. “As demand grows for commodities like these, we have had customers bring samples to test how our equipment would perform. In these tests, we trial various methodologies and scientifically record and compare the results.”

The R&D laboratory prepares samples and conducts particle size analysis using equipment such as pressure filters, drying ovens, sieves, shakers, sizers and separating funnels. When chemical analysis is required, samples are sent to outside laboratories.

Bornman said his division also receives enquiries from existing customers when they face challenges: “We research the application of different methodologies to customer material, often leading to the development of a new product or improvements to our existing products,” he said.

“In addition to providing a solution for the customer, we are also able to contribute to the efficiency of the industry as a whole, with an updated and commercialised product.”

Screening

When it comes to tests on mineral screening, a test rig – located at Multotec’s Spartan headquarters – delivers two primary benefits, according to Chris Oldewage, Technology Manager at Multotec Manufacturing. First, it facilitates the in-house development process of screening media products. Second, it allows screening media to be tested against customer requirements to ensure the right solution is delivered.

“The ongoing research and development behind our screening media products give the industry opportunities to optimise efficiencies and recoveries,” Oldewage says. “However, changing anything on a plant brings risk of unexpected downtime. Our screening test rig can considerably reduce operational risks by proving any changes before they are implemented on site.”

In the controlled environment provided by the screening test rig, customers can view the actual performance of screening media products with material from their mining operations, Multotec says, with the company’s testing protocols generating the data necessary for detailed process analysis. This facilitates well-informed subsequent decisions, the company said.

The screening rig is made up of three test platforms: a vibrating screen, a sieve bend and a static drain screen platform. The vibrating screen can conduct classification tests, wet and dry dewatering tests, product development tests and plant screen simulations. The static drain screen and sieve bend screening test platforms are wet classification, drainage and dewatering tests.

Multotec Process Engineer, PJ Pieters, said accurate scaling of a customer’s on-mine process is vital for achieving representative and relevant test results.

“We gather a range of key data from customers on our test work questionnaire,” Pieters said. “This includes their material tonnages, volumes of water, screen sizes in operation and aperture sizes on panels among other information.”

This ensures sample sizes are representative and the tests accurately reflect what is taking place in the mine’s processes. Tests, meanwhile, are conducted in triplicate runs to ensure a sound scientific basis for the findings.

Oldewage said: “By removing the risk that mines face in trying new solutions, our testing capability smooths the way for valuable innovation to improve screening performance.”

The screening test facility at Multotec also includes a small Lucotec screen and a small wedgewire trommel screen, both for small-scale verification test work.

Cyclones

Multotec’s large scale cyclone rig, meanwhile, can test the performance of a range of cyclone sizes, up to 450 mm diameter. Tests related to classification, desliming and dewatering, as well as dense medium separation using density tracers, can be conducted.

Among the benefits to customers is the ability to test large volumes of samples, as the rig includes a 1,750 litre sump and a 6/4 pump, Multotec said. Flexibility is provided by a variable speed drive connected to the pump, to vary the flow rates as required by the cyclone size.

Dry samples usually need to be blended before testing, and wet samples may need to be dried before blending. The resulting samples from the test must also be scientifically prepared for particle size and chemical analysis. The precision at each stage is vital, as bulk samples as large as 200 kg may need to be reduced to as little as 100 g.

The rig’s infrastructure also includes two Multotec vezin samplers, which are compliant with the highest design standards to provide reliable samples, according to Multotec. “These help to minimise the common errors of manual sampling and ensure that the integrity of the sample is retained,” the company says.

In addition to using the test rig to analyses the customer’s process flowsheet – with Multotec engineers identifying where its range of classification and other products can add value – the company also uses the cyclone test rig for its own product development.

“This on-going process has resulted in a range of cyclones that are lighter, more cost effective, environmentally-friendly and energy efficient,” the company said. “They all contribute to helping customers lower their cost per tonne in a low footprint, sustainable plant operation.”

Spirals

Multotec says its spiral test rig has been adapted in response to the industry’s need to re-treat chrome dumps and upgrade ultra-fine chrome.

Again, located at the company’s headquarters in Spartan, the rig allows eight to 10 different spirals to be erected at a time.

Jeantelle Rust, R&D Engineer at Multotec Process Equipment, said: “With the drive to process tailings in the chrome sector, we have been running tests on a more compressed spiral with a reduced pitch. This reduces the velocity of the very fine particles.”

This configuration works particularly well when dealing with fine material, hence its application in tailings, Rust said. The spiral could offer a cost-efficient way of separating ultra-fine chrome material and recovering valuable product, according to the company.

Rust said: “Such a solution presents an attractive commercial proposition to industry and will also address environmental concerns presented by tailings dumps.”

Using a “mouth-organ product box”, the material being tested on the spiral rig is split into eight product fractions, not just the usual three for product, middlings and tailings. This helps optimise the mass balance for reporting purposes, according to the company.

The spiral test rig has also been used to evolve designs that deal with coarser material, Multotec said. “Customers were looking for a solution to the ‘beaching’ of coarse coal product on the spiral’s surface, for instance,” it explained.

Rust said: “We were able to modify the angles and diameter of the trough to address this challenge. Our ability to make small adjustments to the equipment, and to test material repeatedly at full scale, is the key to finding practical solutions.”

Multotec has also conducted research for producers of mineral sands where head grades were steadily dropping. This necessitated the treatment of larger tonnages, requiring higher capacity spirals.

“Space constraints on the customer’s site meant that adding spirals to their process was not an option,” Rust said.

“Wider spirals were thus tested for higher throughput, with different angles to minimise losses.”

 

Weir’s Trio feeders, crushers and screens up production at Pattison Sand

Weir Minerals has delivered a custom designed plant that has boosted production and increased the product range at a sand and aggregates miner in Iowa, US.

Family-owned Pattison Sand produces a diverse range of products, servicing several industries including infrastructure and construction.

Weir said: “After successfully using a number of Weir Minerals products at their site, Pattison Sand wanted a custom designed plant capable of producing more than seven materials: concrete stone, road rock and base material, asphalt stone, asphalt chips, railroad ballast and manufactured sand. This was a challenging demand considering most aggregates sites in the region typically focus on producing only a few products.”

Eric Jones, Global Service Director of Comminution Aftermarket for Weir Minerals, said when Pattison Sand presented the plan for their sand plant, the company’s integrated solutions team “worked with them to make it a reality”.

The facility, comprising both an underground and open-pit mine, is located on the Mississippi River. It processes highly abrasive materials and, combined with the physical diversity of the site, presented a number of technical and engineering challenges to Weir. On top of this, the company had three months to deliver and commission the plant.

Chance Harvey, Director of Engineering at Pattison Sand, said: “We develop these solutions with Weir Minerals through a lot of trials, successes and failures, and end up getting the results that we need to continue to survive in the marketplace.

“A lot of the options that other equipment manufacturers supply are standard and by the book. Weir Minerals has the ability to work with us to create solutions for our individual issues.”

The site has a unique rail loadout setup where product is dispatched to customers as soon as gradation and quality data is approved. This meant Pattison Sand needed an efficient, dependable plant to meet stringent delivery requirements.

Weir Minerals supplied a number of products to create two primary and secondary crushing stations at the operation. These included a Trio® TF5220 vibrating grizzly feeder, two Trio EF3603 pan feeders and two Trio TP450 cone crushers. Trio scalping, incline and wet incline screens, as well as a Trio TSW4432 fine material washer, were also supplied.

Full training and support was provided, with Weir Minerals regularly on site to help Pattison Sand optimise their entire process and achieve the desired result, Weir said.

It continued: “The flexibility of the custom built plant has allowed Pattison Sand to operate more efficiently, exceed production target and increase their product range.”

Since commissioning the plant, Pattison Sand has been able to produce 500-800 t/H of high-quality aggregate material, which equates to around 2.5 Mt/y of raw product. Four hoppers provide a loadout rate of 500 t/h enabling Pattison Sand to produce a diverse range of products and still meet demanding customer delivery schedules, Weir said.

Jones said: “When customers purchase Trio products they are buying years of experience from people within an organisation that is dedicated to the industry and its customers. We constantly strive to be closer to our customers. It’s not always perfect, but we work through projects together and are honest with each other. It’s that transparency and working with customers like Pattison Sand which really drives the end solution.”