Tag Archives: Multotec

GETTING THE MOST FROM TREATING MINE EFFLUENT

Treating effluent on mines often makes use of reverse osmosis (RO) technology, but low recoveries can raise costs substantially; continuous counter current ion exchange can provide a fit-for-purpose solution.

This is according to Vincent Ridgard, process engineer at Multotec Process Equipment, who notes that RO was initially designed to remove monovalent salt molecules from sea water.

“However, wastewater on mines also includes divalent and trivalent elements, which cause scaling of membranes in RO systems,” Ridgard says. “This means that when a standalone RO plant is utilised to treat these waters, it is operated at lower recoveries to enhance the lifespan of the membranes.”

This results in large volumes of highly concentrated brine streams, he says, which are either recirculated within the system or require very expensive effluent treatment systems. To address these challenges, Multotec offers niche technologies that are suited to treat divalent and trivalent elements in water on mines.

“Through our close partnership with Clean TeQ Water in Australia, we offer mines across Africa a continuous counter current ion exchange technology,” he says. “This uses resin which is more selective to extracting larger molecules.”

As a result, these systems achieve high recoveries of over 90%, so that process water can be re-used within the mine’s process circuits or discharged safely to the environment. The resin-based chemistry removes target species, selectively extracting contaminants through exchanging ionic functional groups that are engineered on the resin beads.

Ridgard notes that, while these scientific principles are well accepted, there has previously not been a suitable technology to truly unlock the significant potential of resin chemistry. Clean TeQ’s ‘moving bed’ solution – supplied to the African market by Multotec – is therefore a game changer.

In contrast to the conventional fixed-bed systems, the use of resin transfer mechanisms allows the continuous ionic filtration (CIF) to handle up to 150 ppm of solids, whereas conventional systems need a 100% clean liquor. Total suspended solids (TSS) and total dissolved solids (TDS) can therefore be simultaneously removed.

It also optimises the inventory of resin, a significant cost contributor to the overall plant, and provides high water recoveries. Other benefits include its low power consumption and its ability to recover valuable trace metals as a by-product.

ENGINEERS LAUD MULTOTEC’S POPULAR ONLINE TRAINING

Restrictions on personal movement due to the Covid-19 lockdown have not stopped the learning process in the mining industry with Multotec seeing unprecedented numbers attending its online training in recent months.

For Wilna Hoffmann, business development manager at Multotec Process Equipment, the lockdown has, in fact, provided an unexpected opportunity to reach even more engineers with valuable technical content and insights.

“I started to adapt our training from conventional to online methods very early in the initial lockdown,” says Hoffmann. “In a series of presentations to a large mining company, we had 74 engineers attending our online session. They spent in total about 556 manhours with specialists from Multotec.”

Multotec’s training initiatives are nothing new; the company has conducted over 1,305 training interventions (2,054 manhours) at Design Houses over the past seven years. The difference, she says, has been the proactive harnessing of the power of digital communication platforms. This delivery channel is also much more efficient, requiring less logistical planning and taking much less time out of the delegates’ busy work schedules.

“The result is that our reach has been dramatically increased,” she says. “In fact, we estimate that in the first four months of lockdown, we have reached as many engineers as we did over the past seven years.”

In addition to the dedicated mining house training, over 2,380 hours of training was provided from April to July this year to more than 415 qualified engineers from about 74 design houses and engineering consultancies. The virtual platforms have also added a new, international dimension to the learning, with engineers attending from as far afield as Australia, Canada, the United Kingdom and India.

Hoffmann highlights that the sessions are not sales-focused, but rather concentrate on the fundamentals of equipment design and application, including formulas, models, efficiencies and losses.

“Sharing insights on the theory and physics of mineral processes – essentially university-level content – makes the training directly relevant to qualified and experienced engineers,” says Hoffmann. As a metallurgist herself, with many years’ experience in a design house environment, she says that none of the training would be possible without the collaboration of her specialist colleagues at Multotec.

The training engages with just about every aspect of a mineral process plant, from spiral concentrators, centrifuges and filter presses to hydrocyclones, dense media separation cyclones and magnetic separation. The sessions also look at the design, operation and selection of mill liners, pumps, sampling technology, trommel screens, static screens, scrubbers, wear linings and water treatment technologies.

“The success of the online training to date has certainly encouraged us to continue with our online learning programme,” she says, adding that the feedback from delegates has been overwhelmingly positive.

“We achieved about 85% approval ratings in the feedback, with delegates wanting to see more of this kind of training,” she says. “The responses rate the quality of knowledge sharing as excellent, and they value the fact that our presentations are unbiased toward any original equipment manufacturer.”

MULTOTEC OPENS NEW SCREEN PANEL PLANT IN CHINA

Bucking global economic trends, mineral processing equipment specialist Multotec has opened a new, larger manufacturing facility in China to meet growing demand.

The 3,200 m2 factory, based in the busy port city of Tianjin about 100 km south-east of Beijing, is over double the size of the previous premises, according to Ken Tuckey, one of the directors of Multotec Screening Systems (Tianjin) Ltd. It focuses on producing the company’s polyurethane screen panels, including specialised panels for fines dewatering and classification.

“The expanded facility was necessary to increase production capacity, as sales have grown rapidly since Multotec became directly involved in this business in 2017,” says Tuckey. “The investment in China is also an important part of Multotec’s global strategy to get manufacturing operations closer to end-customers wherever possible.”

Multotec had taken over the business from Tema Screening Systems in 2017, which had started up in 2006 and focused mainly on the aggregate and quarry sectors. Multotec’s sales have expanded mainly into China’s mining industry, but the factory’s increased capacity is also allowing it to produce for other parts of the world.

Running the operation on the ground since 2018 is general manager He Pu, a local expert with 20 years’ experience in mineral processing. “The new factory has taken careful planning over the past year, and had to obtain a range of strict government approvals,” he says. “Even though the Covid-19 pandemic did present some challenges to our schedule, we were still able to move into the new plant in May this year.”

He Pu highlights the importance of innovation as a key ingredient for any company to break into the Chinese market. This has been vital to the early success of Multotec, which has proven a range of product advances around Africa and other markets. He says that recent improvements in China’s manufacturing sector has also underpinned the success of the local business.

“The focus in the mining sector in China has shifted towards increased efficiencies and improved quality,” He Pu says. “Multotec is now well positioned to take advantage of this especially with the innovative screen panel technology that it can offer the market. This is underpinned by our quality manufacturing processes as well as our excellent local supply chain.”

Multotec’s Chinese company is ISO-accredited with strong in-house quality control expertise, he says. This makes it unnecessary to bring quality control personnel from Multotec head office in South Africa, demonstrating the business’s cost effective and sustainable foundation. The number of local staff members has increased and includes a strong sales team with good links into the mining sector. The company also has distributors and agents across China, bringing services and products closer to the mines.

With the new polyurethane moulding machines, the upgraded plant is running double shifts to optimise production levels. The latest technology equipment – combined with Multotec’s experience and ongoing training in factory – ensure a consistently world class quality of polyurethane panels. Accelerated in-house manufacture is also speeding up the delivery times to local customers.

“The opening of this plant marks the beginning of a new era for Multotec,” says He Pu. “We have ascended to a new level, not only by enlarging the area of the workshop but by adding new equipment.”

He concludes that the availability of Multotec’s innovative panels from the new plant will boost the company’s brand in the Chinese market and create a firm platform for continued growth.

MULTOTEC ADVOCATES JOINING HANDS TO ADVANCE PROCESS TECHNOLOGY

The age of digital technology holds huge potential for equipment performance in the field of mineral processing, but equipment suppliers will make little progress if they work only on their own.

“The inclusion of today’s technologies in mineral processing equipment demands collaboration on an unprecedented level,” says Thomas Holtz, group chief executive officer of Multotec. “To begin with, we need outside specialists to help build digital technology into our existing products. But we also need to cooperate with other process equipment suppliers to ensure that we feed into common systems that make customers’ plants more efficient.”

He highlights the power of sensors, digital data communication and computer analytics to transform how mineral processes are monitored and optimised. Technology can make the plant a safer place and can run processes more efficiently. This includes monitoring wear life, helping mines plan for better maintenance and improve uptime.

“At Multotec, we have invested considerably in applying sensor technology – especially the use of accelerometers,” says Holtz. “The real work, however, comes with the management and interpretation of the data these sensors generate.”

For this reason, data analytics becomes the real value when applying this monitoring technology. He notes that this aspect of product development must generally be conducted with a specialist service provider over a long period of time. Even then, the process is usually arduous.

“Our technology journey to date shows how challenging it is to analyse the data we collect in a way that we can draw conclusions that are useful for our purposes,” he says. “It is relatively easy to monitor vibration levels on a bearing and to generate a trend line on a graph. It is less simple, for example, to automate an operational response to that information.”

Much progress has indeed been made, he says. Through collaboration with a technology partner, Multotec is developing a machine learning process to analyse vibration data from a cyclone. Based on this real-time data, an artificial intelligence server generates alerts related to pre-defined condition levels. He makes the point, though, that each equipment supplier can only monitor those functions within a process circuit in which their equipment performs.

“To fully leverage today’s digital technology, a plant manager needs equivalent information from every item of equipment operating in the circuit,” he says. “This full range of data – coming in from all the equipment – then needs to be synthesised to fully optimise the running of the plant.”

One immediate challenge is that most existing process plants were not built to accommodate the latest technologies. Especially under current cost pressures, retro-fitting entire plants is seldom an option. Sadly, there are not many greenfield operations being opened which may provide an opportunity to apply new ideas and equipment from scratch.

Prevailing mindsets are also an obstacle, argues Holtz. Most suppliers jealously guard their intellectual property, frustrating any attempt at collaboration.

“We need to work toward a new approach, in which each player brings some input based on their area of expertise,” he says. “Many small innovations – when combined – can produce significant progress, and generate a meaningful advance for our mining customers.”

He highlights that all the equipment in a plant needs to talk to a central system or ‘brain’ that will drive the innovation that mines are looking for. Only in this way can mines gain efficiencies through technology and become more sustainable. This, in turn, provides the foundation of success on which their service providers can thrive.

In conclusion, Holtz emphasises the importance of gradual and sustained technological progress. Many new technology ideas are met with unrealistic expectations, and people are disillusioned when these are not immediately realised.

“Closer and ongoing collaboration with all stakeholders – including mines and design houses – will allow us to achieve the important long-terms benefits that technology can and must deliver to our industry,” he concludes.

TOOLROOM UPGRADES BOOST QUALITY, PRODUCTIVITY AT MULTOTEC

Continued growth in demand for Multotec Manufacturing’s screen panels has led the company to expand and upgrade the dedicated toolroom at its extensive manufacturing facilities in Spartan, Gauteng.

According to Ian Chapman, engineering manager at Multotec Manufacturing, these technology investments have accelerated the tool manufacturing process and delivered better tool finishes. This translates into enhanced product quality, greater speed to market and more cost effectiveness for the end-customer.

The tools required are mainly for rubber and polyurethane injection moulding, rubber compression moulding and cast polyurethane products. The wide variety of tooling produced includes ‘mother moulds’ and components such as frame bars, cores and inserts.

“By 2015, our success in growing markets had placed considerable demand on our toolroom,” Chapman says. “This led to the replacement of two CNC milling machines and adding two new wire electric discharge machines (EDMs) in recent years.”

The new milling machines use specialised Heidenhain controllers, which strengthen Multotec’s jobbing capability for customised tooling. Based on the specification from the sales team, drawings are created for the company’s tool and dye makers. They, in turn, convert these drawings using computer-aided manufacturing (CAM) software to create the tool-path for the CNC machine.

“Our experts’ familiarity with the Heidenhain language speeds up our work and avoids human error,” he notes.

Wire EDM machines are another key resource in the toolroom, using electrical erosion technology to cut relatively long tool-pieces accurately and finely.

“Unlike a milling machine – where there is contact between a tool and a work-piece – on the EDM there is no engagement with the wire and hence no forces to accommodate and few residual stresses,” Chapman says. “This allows us to cut pre-hardened steel without distorting its shape, creating very fine tolerances in our finished tooling.”

To augment the existing two EDMs, a third was acquired in 2018, with even larger wire spools than the previous models. This allows longer production runs of up to 90 hours, improving cutting strategies and productivity. So successful was this investment that a fourth wire EDM was purchased and installed in 2019.

INNOVATIVE PULPING CHUTE CUTS SCRUBBING COSTS AT EKAPA

A revolutionary new concept in fines scrubbing has been installed by Ekapa Minerals at its Combined Treatment Plant (CTP) in Kimberley processing both virgin underground kimberlite as well as tailings for retreatment , and it is proving itself as a game-changer.

The innovation, developed by Multotec Wear Linings, is a pulping chute that scrubs and washes the recrushed product after it has passed through the High Pressure Grinding Rolls (HPGR) interparticle tertiary crushing circuit. The important advantage here, according to Multotec Wear Linings projects sales manager John Britton, is that it performs the scrubbing action faster and more efficiently than a traditional rotary scrubber would, and at much lower cost.

Multotec commissioned two of these pulping chutes at Ekapa Minerals in late-2019, where they have been operating consistently and in line with expectations. With the use of patented wave generators, the pulping chute uses the gravitational energy from the slurry flow to create a constant turbulent mixing action that releases the mud, clay and slime sticking to the kimberlite particles.

According to KEM CEO Jahn Hohne, the pulping chutes are a welcome contribution to the company’s cost saving efforts, and a clear demonstration of Multotec’s expertise in developing value-adding solutions in the mining sector.

“The dual chute pulping plant is ideally suited to de-conglomerating the HPGR cake product and is exceeding expectations in efficiency and effectiveness at over 600 tph, which is a major relief on the existing overloaded pair of CTP scrubbers. The net result is a meaningful increase of up to 20% throughput capacity of the entire processing plant which substantially improves the economy of scale of CTP, feeding directly to the bottom line,” he says.

Britton highlights the efficiency of the system, which is able to aggressively scrub the material in just three to four seconds as it passes through the chute. This represents just a fraction of the usual retention time in a rotary scrubber, which is three to four minutes. He also emphasises the drastic reduction in running cost which the pulping chute achieves.

“From our experience of plant layouts and flow diagrams, it is clear that fines scrubbers are significant contributors to a plant’s capital, operating and maintenance costs,” he says. “Scrubbers are equipped with large drives with gears and gearboxes to rotate the drum. They are high consumers of power and require mechanical component maintenance which means higher operating costs.”

Substantial structures and supports are also needed for the scrubber and its drive mechanisms. In designing the pulping chute, Multotec sought a simplified solution, he says. In addition to improving scrubbing efficiency, the objective included reducing the cost of replacing scrubber liners and the downtime that this demanded. The cost of replacing the steel shell of a scrubber – which was constantly subject to stress, wear and fatigue – was another cost to be considered.

The pulping chute, by contrast, is a stationery and much simplified innovation, focused on the scrubbing of fines less than 32 mm in size. Slurry deflectors located at the top end of the scrubbing chute direct at least part of the slurry away from the scrubbing chute floor. This curls into an arched form which flows backwards into the approaching flow of slurry, creating theturbulent scrubbing effect.

“We custom-design the chutes to suit the application and can increase chute capacity to up to 800 tons per hour,” says Britton. “This is achieved with no moving parts, bearings, hydraulic packs or girth gears; the only power required is to supply material and water to the receiving chute. These actions are also required to feed the scrubber, then gravity takes over and provides the required energy”

Maintenance is also streamlined by designing the chute in segments. Should one segment be wearing more than others, it can be quickly removed and replaced – putting the chute back into operation while the original segment is refurbished as a spare.

Britton notes that the pulping chute has drawn interest from other diamond producers in southern Africa, Australia and Canada. It can also be applied in commodity sectors such as coal, platinum, chrome, iron ore and mineral sands.

NEW SPIRAL MEANS BETTER RECOVERIES FOR FERROCHROME – AND BEYOND

Following years of detailed test work in the ferrochrome sector, Multotec has successfully developed and proven a spiral concentrator that eliminates beaching and enhances recoveries in the 1 mm to 3 mm fractions of high density material.

Significantly, when compared to traditional spirals the new spiral has shown extraordinarily higher metal recoveries, even for minus 1 mm fractions in ferrochrome slag.

“Our SC25 spiral concentrator features steeper angles which facilitate the flow of material and increase separation efficiency,” says Hlayisi Baloyi, applications engineer at Multotec.

“It also widens the particle size range that can be treated by the spiral. Traditionally, spirals would struggle to efficiently treat material above 1 mm in heavy mineral applications, but this spiral can go well beyond that. The spiral has been a game changer even for the minus 1mm size range where higher separation efficiencies have been achieved on chromite ore.”

Baloyi says that this innovation has provided the minerals processing sector with an exciting alternative to jigs in the minus 3 to plus 1 size range, which have been one of the conventional methods of separating larger particles. The solution is cost effective as spirals use no electricity, and are also easy to maintain. So attractive is the new model that the first order for the commercialised version has already been placed.

“Taking ferrochrome samples from a number of mines over a period of two to three years, we conducted extensive test work on these at our well-equipped testing facility in Spartan near Johannesburg,” he says. “Leveraging this data with our in-house engineering design capacity, we were able to develop the optimal solution and locally manufacture the new spiral concentrator.”

The institutional knowledge within Multotec has been developed over more than four decades, including valuable expertise in fluid dynamics. Hands-on experience in test work and design allows the development of prototypes that solve customers’ specific challenges – followed by scaled-up local production of equipment to match market demand.

The economic benefits of the Multotec SC25 spiral for ferrochrome producers are substantial, as some plants were losing the value of their 1 to 3 mm material to the tailings storage facility. Many of those who used jigs to treat this fraction were also finding that their efficiencies were low.

“Ferrochrome is not the only commodity that we have successfully tested,” says Refentse Molehe, process engineer at Multotec. “We have even seen improved recovery in heavy minerals below 1 mm size, alluvial chrome, manganese slag and there is potential in industrial recycling.”

The recycling application opens up options for ‘urban mining’ – the recovery of metal particles from associated waste. Multotec has received a number of requests and conducted tests to recover metals from recycled electronic goods and from customers who intend to recover metal from industrial scrap.

CUSTOM SAMPLER SOLUTION FOR GUINEAN BAUXITE PRODUCER

Accurate sampling is key to the success of the valuable bauxite industry in the west African country of Guinea, and Multotec Process Equipment’s high-precision sampling equipment is playing its part.

Multotec has recently provided two tariff sampling plants to a major bauxite producer, including what is possibly one of the largest hammer samplers in the world. One of the plants is located at the bauxite mining operation itself, while the other is at the export facility where the high-grade bauxite is loaded onto ships.

According to Willem Slabbert, sampling and magnetics specialist at Multotec Process Equipment, the samplers serve a vital role in representatively measuring the quality of the material mined and then exported, as well as its physical characteristics.

“At the mine, the sampling plant gives the mining company and their third-party mining contractor a scientific basis on which to check compliance with their contractual requirements,” says Slabbert. “Similarly, the plant at the export facility assures the end-customer of the quality of bauxite they are purchasing.”

The solution designed for this specific application includes hammer samplers, double-roll crushers, rotating plate dividers, feeder conveyors and barcoded carousels to link the sampling plant’s hourly performance to the indexed samples produced. There is also protection equipment – a moisture analyser, overbelt magnet and metal detector – and inter-sampling plant conveyors.

“The plants were designed as a holistic solution, to deliver measurements in line with the international standard ISO8685 – ensuring that both sides of a contractual agreement can feel confident in the results,” he says. “They are also fully automatic and PLC-controlled for maximum efficiency.”

He highlights that the sampling and materials handling solution was based on extensive test work carried out at Multotec’s well-equipped facilities in Spartan near Johannesburg. Crusher tests were also done on the specific bauxite, which comprised a substrate material with very hard embedded nodules.

“We identified custom-designed, heavy-duty, double-roll crushers as the optimal solution to deal with the extreme hardness of the nodules in the material,” he says. “The abrasiveness and stickiness of the Guinean bauxite also required low-friction liners to be designed into each plant.”

Supporting its installations with highly experienced technicians, Multotec also has a West African branch in Ghana which sources local components for customers. The branch has capacity to deliver support and maintenance services as well as provide training to local operators, in English and in French.

Multotec Process Equipment has plenty of experience in sampling bauxite in Guinea, says Slabbert, with another sampling plant installed two decades ago for another bauxite producer.

SUCCESS FOR NEW CERADOX HIGH IMPACT SCREEN PANEL

Combining decades of experience with its leading R&D and manufacturing capability, Multotec has developed a high-impact screen panel that cuts plant downtime and boosts mine productivity.

The Ceradox panel – incorporating both Hardox blocks and alumina ceramic tiles – boasts more than double the wear life of traditional rubber panels. The innovation was developed during 2019 in response to a request from an iron ore mining customer in Australia’s Pilbara region. Three months of testing delivered results that exceeded expectations, said Multotec screening product manager Shawn Faba.

“The customer needed a panel with an extended wear life, so that they only needed to conduct replacements during the regular maintenance shut-down every 12 weeks,” says Faba. “Our testing demonstrated that the panels were lasting 24 weeks and longer.”

Through a close collaboration between Multotec South Africa, Multotec Australia and the customer, an innovative solution was developed and proved for a demanding application on scalper screens.

“Designed for the impact area of the scalper screen, the Ceradox panel must withstand the impact of material up to 300 mm in size, falling from a discharge height of up to three metres,” he says. “It must also resist high levels of abrasion from the ore.”

The resulting design leverages the impact strength of the Hardox blocks and the abrasion resistance of the ceramic tiles, embedded in Multotec’s proprietary rubber formulation which helps absorb the energy of the falling material. The panels are manufactured locally at Multotec’s high-volume facilities in Gauteng, which include a rubber mixing plant run by experienced rubber specialists.

Faba notes that the 305 mm square Ceradox panels can be manufactured to different thicknesses from 50 mm to 100 mm.

“With our local manufacturing capability, we can achieve short lead-times and deliver to anywhere in the world,” he says. Multotec already supplies about 35% of the screening media to the iron ore mines in the Pilbara area.

ON-SITE TESTWORK AT REFINERY PAVES WAY TO QUALITY BOOST

On-site testwork at a South African base metal refinery allowed Multotec to prove its sievebend solution for improving the quality of the customer’s product to market.

According to PJ Pieters, process engineer at Multotec, the refinery was looking for the most efficient way to reduce impurities to less than 200 parts per million in the product stream.

“As the contaminants were found mainly in a specific size fraction, the aim was to remove this fraction by classification using a sievebend,” says Pieters. “To test this proposal, we used our mobile sievebend test unit which we could take onto the customer’s site and link up to one of the product streams in the plant.”

This provided a convenient way to conduct testing under normal plant operating conditions. It also meant there was no need to remove any valuable mineral product from the site, which could demand onerous security compliance procedures. The tests took only a week to conduct, after the mobile units were installed.

“The tests were conducted to reduce impurities and to measure the effect of the sievebend on the downstream screen scroll centrifuge,” he says. “We managed to achieve the product quality goal, while also maintaining optimal centrifuge performance in terms of the customer’s product moisture requirement.”

The addition of a sievebend to the process will not increase the energy costs as the machine is operated under normal gravity conditions and is compact enough to fit inline between existing process equipment.

To withstand the highly corrosive application, the sievebend and its housing were manufactured in stainless steel. By using appropriate sampling techniques, the testwork was able to deliver very representative results. This gave the customer an accurate expectation of the precise results that a full-scale installation would deliver.

“This kind of testwork adds confidence to the customer’s decision to invest in a specific solution,” Pieters says. “It is also part of Multotec’s contribution to continually improve customers’ process efficiency; we work to provide the customer with the best knowledge and products to optimise their plants.”

Another element of the valued added by the sievebend, says Pieters, is that the refinery is likely to save on potential penalties arising from impurity levels in the saleable product. Multotec also provides after-sales optimisation and support to ensure on-going benefit from the innovations applied.