Tag Archives: Multotec

MULTOTEC’S NEW SPIRAL FOR RETREATING ULTRA-FINES

Multotec has taken another innovative step to help customers recover more of their valuable ultra-fine material so that it does not go to waste in the discard.

As a leading designer and manufacturer of spiral concentrators, Multotec has released its UX7 spiral which focuses on recovering material in the particle size range of 75 microns and smaller. Refentse Molehe, process engineer at Multotec, says the success of the Multotec UX7 is based on extensive in-house test work, which has led to improvements and around 13% better recovery.

“Much of the testing was conducted on chrome, manganese and iron ore, but the UX7 spiral can be as easily applied to copper, platinum and other metals,” says Molehe. “This is an exciting development for the sector, as we have seen growing interest from our customers in gaining financial value from material which has traditionally ended up in tailings storage facilities.”

She notes that efforts to improve the recovery of ultra-fines have used a range of technologies, but spirals have always been regarded as a highly reliable and energy efficient solution. Multotec’s continuous improvement of its spiral technology to suit customer needs now opens the door for customers to cost effectively re-treat their tailings dams to recover valuable ultra-fine material. 

“In addition to its ability to recover ultra-fines, the Multotec UX7 spiral benefits from the various advantages shared by spiral concentrators,” she says. “These include the lower environmental risk and cost due to the absence of chemicals, and the low maintenance of this technology as a result of having no moving parts.”

Multotec’s decades of on-the-ground experience in mineral processing – and its depth of expertise in a range of related disciplines – equip the company to provide a customised, full flow sheet solution. Molehe emphasises that each application of the Multotec UX7 spiral will be based on an in-depth understanding of the customer’s operating conditions, fine-tuned by extensive testing of material to ensure the optimal result.

“Once we can confirm that the UX7 spiral is the appropriate solution for the customer’s operation, then we build in the throughput and capacity requirements and accordingly design the flowsheet to accommodate the specifications to be achieved,” she concludes. 

MULTOTEC LEADS THE WAY IN COMPOSITE LINERS FOR LARGE SAG MILLS

As the mining industry moves to larger semi-autogenous grinding (SAG) mills for higher productivity, Multotec is developing and applying innovative liner designs to optimise liner performance, mill efficiency and liner wear life.

“Our strong analysis capabilities in the design process – including discrete element analysis (DEM) and finite element analysis (FEA) – allow us to continuously evolve the application of our composite liners,” says Sam Hearn, global sales and business development manager, Multotec. 

Hearn highlights how Multotec uses DEM software to simulate the interaction between the mill charge and the liners, and to evaluate liner profile over the life of the liner. 

“The DEM analysis considers a range of variables such as the ore’s bond work index, its specific gravity, the size of the grinding media, the mill speed and the slurry density,” he says. “Sophisticated simulation capability allows us to accurately model the performance and wear of our mill liners. This includes predicting the liners’ wear life, to avoid unscheduled downtime and to extend the time between replacements.”

Emphasising that no two mill liner applications are identical, Hearn says that this simulation can guide very specific refinements in the liner design for each customer. A detailed understanding of the operating conditions is vital to ensure that the final solution delivers optimal results.

He notes that the traditional use of steel liners in large SAG mills presents a number of challenges. For instance, there may be bending stress inside the steel liner due to inexact fitting on the mill’s curved surface, and the higher rigidity of steel compared to rubber makes it less than optimal for absorbing the energy of rock material inside the mill.

“This is where our composite liners come into their own,” he says. “These innovative liners combine the impact resistance of Hardox 500 steel inserts and the absorption capacity of our specially formulated wear-resistant rubber compound. Through the simulation, the structural integrity of the liners can be verified, while the geometric layout of the liners can be optimised.”

The composite liners are locally manufactured at Multotec’s extensive facility in Spartan, Gauteng, in an advanced process that includes its unique submerged cutting technique to preserve the surface hardness of the liners.

“We combine our innovative design capacity with the latest tooling capability and production technology for large-scale manufacture,” says Hearn. Following the design and manufacturing process, Multotec conducts field trials to compare to the relative performance of composite liners and steel liners. 

“We are confident that, given our product improvement processes and simulation ability, the wear‑life of our liners will achieve and often exceed expectations,” he says.

EVOLUTION OF CYCLONES TO IMPROVE COAL FINES RECOVERY

Continuous improvement of Multotec classification cyclones helps customers meet both commercial and environmental imperatives in the coal sector, according to Ernst Bekker, product specialist cyclones at Multotec. 

“Today, there is an intense focus on the beneficiation of coal fines, which in the past were generally discarded,” says Bekker. “There is greater awareness of the environmental impact, and it also makes good economic sense to recover more.”

He highlights, however, that dewatering of fines can be costly. Multotec’s efforts to make the process more cost effective have included the investigation of alternative inlet designs, which achieve more efficient separation, especially with fine coal. Also, important has been the incorporation of alternative wear materials, to extend the life span of these cyclones.

“Our focus is on the mechanical life of our units and their physical ability to last, but we also want to extend their efficiency life cycle, so that they perform well for longer,” he says. Ongoing wear creates undulations on the inner surface of a cyclone, for instance, and this causes inefficiencies. 

“Ceramic tiles might last longer, but other materials might retain a smoother surface for better separation,” he says. “Using these alternative materials, we can design custom solutions to suit the application; this ensures the customer is always getting optimal value throughout our cyclones’ entire lifespan.”

He also notes that the company’s overall sensor development programme is giving attention to monitoring wear lining thickness and performance conditions in classification cyclones. 

“With sensor technology, we will be able to pick up roping conditions in the spigot, for example,” he says. “We believe there is even scope with these units to leverage artificial intelligence to help us achieve optimal operating conditions.”

MULTOTEC PIONEERS INTRICATE DESIGNS IN SOLID CERAMICS

An innovative ceramic-based solution from Multotec has opened the door for a range of componentry to be shaped using pressed alumina ceramics – for high wear resistance and longer wear life.

According to Boyd Butterworth, sales engineer at Multotec Wear Linings, the opportunity arose when a chrome smelter in the Steelpoort area of South Africa’s Limpopo province was searching for a more cost-effective solution for certain wear parts in their rotary dryer multi-cyclone arrangement. 

“The customer initially required the fabrication and ceramic lining of steel components in the multi-dryer cyclones,” says Butterworth. “The units are employed in the process of drying chromite ore particles and other feed material on its way to the pelletising section of the plant.”

The units are essentially dust cyclones – rather than the process or separation cyclones that Multotec supplies – and are subject to aggressive wear. The feed to these multi-dryer cyclones typically consists of chromite ore, reductants such as anthracite, char, coke and coal and fluxes like quartzite, dolomite and lime. 

“The multi-dryer cyclone has four main components, made initially of steel and later lined with ceramics in response to the rapid replacement rate,” he says. “The wear rate is exacerbated by the high velocity of the material, which is required in order for it to remain in suspension while passing through the system.”

The customer’s eagerness to find a more effective solution allowed Multotec to present an unusual – perhaps unique – concept: solid ceramic components custom-shaped for this specific purpose. 

Butterworth notes that the previous installation of standard ceramic tiles by a competitor did not adequately protect the components from the highly abrasive material which, moving at about 18m/s, was still leading to frequent component replacements.

“Our proposal was to produce a solid ceramic blade and dome arrangement, as well as to provide the rest of the tube and inlet sections with engineered ceramics, installed at a very high standard,” he says. 

Paving the way for this solution was this local manufacturing facility’s highly specialised and innovative new fabrication technique.  The ceramics are shaped into various complex and intricate designs while they are in the ‘green phase’ of production, using state-of-the art CNC technology.

“Thanks to this technique , we can produce solid  alumina ceramic machine  components,” he says.

Butterworth concludes that the company’s research to date suggests that this might be the first time that components like these have been produced from pressed alumina ceramics – making them a pioneering achievement. 

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.