Tag Archives: vibrating screens

Kwatani large vibrating screen customisation pays off

Process plant designers often underestimate the movement of large vibrating screens when these machines start and stop, a challenge for which Kwatani says it has found an innovative and cost effective solution.

According to Kwatani’s Chief Operating Officer, Kenny Mayhew-Ridgers, the company has achieved considerable improvements in many screening applications by selectively fitting torsional springs alongside coil springs.

“It is well known that the vibrating motion of a screen impacts on the building and structural accessories around it,” Mayhew-Ridgers says. “This vibration is addressed by fitting isolators between the screen and the plant floor, and by constructing the plant building to certain minimum structural specifications.”

However, the focus is often on the frequencies that the screen generates in its steady-state phase – or the normal running phase – rather than during the transient phases when the screen is starting up or slowing down to a stop, Kwatni says.

Mayhew-Ridgers highlights that it is during these transient phases that the screen’s movement becomes amplified and potentially most destructive. Isolators between the screen and the floor – common among which are coil springs and rubber buffers – are meant to absorb vibrations and prevent damage to surrounding infrastructure. However, the transient phases, especially when stopping, can generate considerable sideways movement of the screen, which must be avoided.

“Traditional isolators like coil springs usually perform well in controlling the up-and-down movement of the screen,” he says. “Our experience is that the sideways movement, which is induced most strongly when the machine stops, can be better controlled by torsional springs.”

However, he notes that coil springs retain the advantages of being cost effective and providing a good linear isolation of the screen from the building structure. In this respect, their isolation characteristics are generally better than rubber buffers which excel in terms of their damping qualities.

“The torsional spring provides the best of both worlds, giving a good linear range for compression during operation while also becoming non-linear like the rubber buffer during stopping,” Mayhew-Ridgers says.

Using its experience observing screens operating in the field, Kwatani has developed and trialled various solutions in its dedicated testing centre at its headquarters in Kempton Park, South Africa. By optimising the best combination of coil springs and torsional springs, the company says it has succeeded in achieving the best results for customers.

“It’s not that torsional springs are better than coil springs,” Mayhew-Ridgers says. “It is about finding the right combination – through intensive testing and adaptation – for the customer’s particular requirements; we have both the expertise and the equipment to do this.”

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.

MBE Minerals expanding vibrating screen sales in southern Africa

Leveraging decades of industry experience and in-house design expertise, MBE Minerals says it is strengthening its footprint of vibrating screens across a range of commodities.

Sales Manager, Graham Standers, says the company has recently supplied 15 new screens to mining customers in coal, diamonds, iron ore and manganese. These operations are based in South Africa, Botswana and Australia. MBE Minerals has also fully refurbished a further four screens to ‘as new’ condition as they approached the end of their planned lifecycle, the company said.

“We place high priority on design capacity, to ensure that every screen suits the application and material it must screen,” Standers said. “Five of the screens supplied were newly designed to suit changing customer needs and processes.”

Each screen is designed by the company’s design office, and the design is then confirmed by finite element analysis through highly specialised software using data from the drawing model, according to the company.

“We have also introduced a range of screens designed specifically for fine coal dewatering, using a design which has proven to be cost effective, efficient and reliable,” Standers says. “Focus was placed on the design of the screen deck support system and screen drive, with a view to reducing downtime by minimising maintenance and enhancing reliability.”

The design is efficient in terms of the required spares stockholding, further reducing the screen’s overall lifecycle costs, according to the company.

“Our unique T-Lock pinless panel fastening system for polyurethane screen panels also significantly reduces the need to hold spares in stock, while reducing the changeout time for screen panels,” he says.

Technical and sales staff conduct regular on-site visits to customers to carry out inspections of equipment in operation. The teams report on equipment condition and performance, and provide customers with value-adding feedback and advice.

MBE Minerals – previously known as Humboldt Wedag – has been designing, manufacturing, installing and servicing vibrating screens in southern Africa for over 40 years.

“Our record for reliability is well known, with some of our units having been in service for over 20 years,” Standers says.

Weir Minerals Africa putting newly designed vibrating screens to the test

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

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

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

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

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

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

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

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

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

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

Kwatani upskills Northern Cape contractor to carry out maintenance work

Specialist vibrating equipment manufacturer, Kwatani, says it leveraging a recent multi-year service contract with a large mining customer in the Northern Cape of South Africa to further boost the area’s local economy.

Kim Schoepflin, CEO of Kwatani, said: “Our branch near the customer’s mining operation has for many years employed and developed local expertise. Our latest initiative takes this further, by upskilling a local sub-contractor to conduct certain maintenance work on our behalf.”

A lengthy selection process was conducted by Kwatani to find a suitable sub-contractor, followed by ongoing training to empower artisans and other workers with specialised skills. Schoepflin says it was also important to involve the mine itself, so that it remained confident in the strength of its supply chain.

“Promoting local employment, skills and sustainability cannot be a tick-box exercise,” Schoepflin says. “It has to be based on proper engagement, hands-on training and the sub-contractor’s own commitment.”

Mining legislation and regulatory pressure can tempt stakeholders to rush such a process, she warned. “This would be a mistake; rather, it should be treated as an opportunity to strengthen the capability of all stakeholders.”

Kwatani’s 35 years of experience in heavy duty minerals applications means the OEM now has around 800 vibrating screens and feeders in the Northern Cape. The maintenance contract is an ideal opportunity to involve and foster the technical capability of local players, Schoepflin says.

It was vital that the chosen sub-contractor already had considerable experience and capacity, equipment and relevant expertise, according to the company.

“As a South Africa OEM with our own technologies and intellectual property, we are able to certify the sub-contractor and their quality of work,” Schoepflin says. “Phase 1 of our initiative will see them conducting basic service and maintenance functions.”

Kwatani retains responsibility for all work conducted, and continues with services such as detailed technical inspections, engineering support, on-site testing and diagnosis. It also supplies OEM spare parts, ensuring quality control, increased lifecycle time and reduced downtime, the company said.

Schoepflin noted that communities countrywide are eager to see more benefits from economic activity, and the country’s Mining Charter provides clear guidance on how mining companies can contribute to this process. “Kwatani’s mining customer is therefore also eager and incentivised to promote local businesses, both directly and through the supply chains of its main local contractors,” Kwatani said.

Schoepflin highlights the importance of supporting local firms to build sustainability in the local economy. This also strengthens the skills base for this economy to diversify, making it less dependent on mining and more resilient to commodity cycles and eventual mine closure.

“Our own business is local from the ground up, sourcing 99% of direct purchases from inside South Africa,” she says. “So, we understand the positive role that local procurement and skills development can play.”

It also makes financial sense to root the company’s cost base in the local currency, making it less vulnerable to foreign exchange fluctuations and allowing more affordable and consistent pricing.

“Working collaboratively with our mining customers and businesses close to their operations, we can help spread local economic benefits,” she says. “In turn, we can continue to develop our focus on leading-edge technology and quality manufacture.”

Kwatani registers global mining demand for vibrating equipment

Kwatani’s vibrating screens and feeders are continuing to find a market in the mining industry, with a number of orders recently secured from diamond, coal, zinc and platinum operations.

The company’s custom engineered products are now in some of the world’s largest mines, and many customers have standardised on their screens to ensure lowest cost of ownership and high performance, according to General Manager, Sales and Service, Jan Schoepflin.

“While our base and core market are in Africa, the global demand for Kwatani products has grown rapidly. A leading diamond mining company in Russia is very pleased with Kwatani screens at their newest operation and specified Kwatani for future projects,” Schoepflin says.

In another order from a large diamond operation, this time in South Africa, the customer replaced the last of its competitor screens with a Kwatani unit. Schoepflin says this is because it has enjoyed years without unplanned stoppages by using Kwatani screens.

At a local brownfield diamond expansion project, the company’s multi-slope banana screens were matched to the available plant footprint, raising throughput from 250 t/h to 500 t/h and, later, breaking the mine’s tonnage record.

“While screening in heavy minerals is Kwatani’s stronghold, the company has moved extensively into coal, supplying the country’s (South Africa’s) leading coal producer with no fewer than 45 items of large screening equipment, including out-sized 4.3-m-wide units,” the company said.

Other recent coal-related orders included run-of-mine screens for a medium-sized coal mine in Mpumalanga, South Africa. Again, competitor equipment was replaced by custom designed screens with optimised deck angles, which significantly increased tonnage, according to the company.

“The positive results achieved with the Kwatani equipment also led to additional orders for the mine’s expansion,” Kwatani said.

For world largest zinc mine, Kwatani was contracted to supply all the screens, while, at Africa’s largest iron ore mine, the company recently completed two projects, renewing existing equipment with updated solutions and replacing 24 items of competitor equipment.

“The platinum sector is also keeping Kwatani busy, not just in South Africa but over the border in Zimbabwe too,” Kwatani says. A recent turnkey solution focused on platinum by-product chromite, where the company supplied a complete solution which included feeder, dryer and screen to treat chromite of 45 micron size at 15 t/h.

Schoepflin said: “Our screens have been a popular choice for modular gold plants going to West Africa as well as Central and South America. We also supplied to two of Africa’s largest copper producers in Zambia, to a tanzanite producer in Tanzania, and repeat orders to a manganese mine in Ghana.”