Tag Archives: Kwatani

KWATANI’S HUGE SCREEN ORDER INCLUDES LARGEST UNITS YET

In the single largest order for vibrating screens secured from any mine in the past two years, Kwatani has shown its mettle by supplying some of the largest vibrating screens in Africa to the world’s leading opencast coal complex.

According to Kwatani CEO Kim Schoepflin, the contract comprised 44 large screens boasting widths of up to 4,3 metres.

“Our equipment may be large and heavy, but each individual unit has been customised for its specific application, to efficiently handle the ore required,” says Schoepflin. “Moreover, the vibrating unit must be engineered to seamlessly fit into a new or existing building, and must operate in harmony with the rest of the processing plant.”

Among the larger units in the order were two double-deck, run-of-mine screens measuring 3 metres wide by 9 metres long, as well as three 2,4 metres by 6 metres degradation screens which will be installed in the mine’s drum plant. Also being supplied are twenty three screens and three vibrating pan feeders for the cyclone plant.

There are sixteen drain and rinse screens in the contract, four of which are generously sized at 4,3 metres by 7 metres, driven by two large gearboxes which deliver a centrifugal force of over 460 kN each.

“The successful handling of this magnitude of contract is a testament to Kwatani’s technical capability,” she says, “as we can handle these larger contracts while continuing to service all our other customers.”

Schoepflin highlights the skills and passion of the company’s family of 160 employees, combined with its extensive and well-equipped manufacturing facility in Spartan near Johannesburg.

“The vibrating screen comprises of thousands of different parts and components, each requiring precision engineering and a number of fabrication processes, which at the end are carefully assembled by dedicated staff,” she says.

She adds that Kwatani is the only OEM of vibrating equipment to engineer, assemble and test its exciter gearboxes in-house and at full load on its fit-for-purpose test bench – ensuring that every gearbox performs optimally before dispatch to a customer.

KWATANI SCREENS FOR ELIKHULU RETREATMENT PLANT

Engineering group DRA has ordered six large screens from Kwatani for the R1,6 billion Elikhulu gold tailings retreatment plant facility at Pan African Resources’ Evander operation in Mpumalanga.

“Kwatani was involved from an early stage in this project, so we were able to custom design this equipment at the study phase, allowing the EPC to readily integrate the design into the plant design,” says Kwatani CEO Kim Schoepflin. “Our focus here was to deliver a cost effective, fit-for-purpose solution to the customer that is technically appropriate to their needs; which is to retreat 1 million tonnes per month of gold tailings.”

Cognisant of the price pressures on all stakeholders, Kwatani was able to hold the price from the original quote date through to final agreement. Making the customer’s purchasing decision easier was also Kwatani’s substantial reference base in the gold sector, as well as at the Evander operations.

“We also helped the EPC with designs for ancillary equipment, assisting in holding down costs for the overall plant structure,” says Schoepflin.

Four of the six screens – the two trash screens and two carbon safety screens – are in excess of three metres wide, feeding 1,500 tonnes per hour. The remaining units comprise one regenerated carbon screen and one loaded carbon screen, through which some 2,000 m3 of slurry will pass per hour.

“We designed these six large screens to facilitate a commonality of spares in the plant, so that parts will be easily interchangeable. This will reduce the necessity for a holding a large inventory of these items,” she says.

She emphasised the low margins inherent to gold retreatment operations, highlighting the importance of reliability in the way that Kwatani equipment is designed, tested and maintained.

“Uptime of the plant is a key factor in sustaining a profitable operation in this sector, so we place high priority on both the process duty that our units must achieve and their mechanical durability to achieve low cost of ownership over their life-times,” she says.

KWATANI TAKES RUGGED SCREEN DESIGN TO NEW HEIGHTS

Spartan-based vibrating screen specialist Kwatani is building one of its strongest and heaviest screens yet, to undertake punishing duty at a South African iron ore mine.

The 54 tonne scalping screen – measuring over 10 metres in length and with a 3,7 metre width – is a single-line unit that will handle about 7,000 tonnes of run-of-mine iron ore per hour. It will take feed from a primary crusher with a top size of 400 mm, although the dimension of these boulders may still be up to 800 mm long.

“This run-of-mine feed will place tremendous load on the screen, particularly due to the impact and weight of the oversize rocks,” says Kwatani CEO Kim Schoepflin. “Significantly, a large portion of the material – as much as 50% of the feed – will move over the full length of the screen without passing through the apertures, so the screen must effectively ‘convey’ these heavy boulders without incurring damage.”

This also means that the bed depth will be relatively high, requiring the design to accommodate a bed of about 800 mm of material on the feed end and about 500 mm on the discharge end. Iron ore is a heavy material, so a bulk density factor of 2,5 has been applied to the design specifications.

Vibrating with a stroke that applies around five times the gravitational acceleration (5G’s) on the material, the mass of the rocks is effectively increased by five times, according to the Kwatani’s chief operating officer Kenny Mayhew-Ridgers.

“This places a very high requirement on the machine’s technical specifications and durability, so the mine has been very careful to choose a supplier that they trust completely to design and manufacture a unit of this capacity,” says Mayhew-Ridgers. “Even the panels had to be designed with internal structures so they could withstand the magnitude of these forces.”

Kim Schoepflin, ceo of Kwatani.

Schoepflin emphasises that the unit’s single-line status makes it a key item of equipment on site, with several parts of the process plant heavily reliant on its throughput.

“It is therefore vital that the screen runs reliably and continuously, as any stoppage will in turn disrupt the whole plant,” she says. “Uptime is an absolute non-negotiable.”

She highlights Kwatani’s capacity to design, manufacture, test, commission and maintain screens of this capacity and ruggedness.

“Our depth of expertise and experience in the field, combined with our substantial facilities and quality standards, equips us to custom-design and engineer fit-for-purpose machines that handle high tonnages reliably while doing the duty that customers demand,” she says.

KWATANI SAYS ON SPEC AND ON TIME ARE KEYS TO SERVING EPCS AND MINES

Faced with the ongoing challenge of being price sensitive in new capital projects, original equipment manufacturers (OEMs) must also ensure that their product and service offering helps create a sustainable foundation for the end customer’s ongoing profitability and efficiency.

“Being cost competitive upfront includes delivering on time and on specification,” says Kim Schoepflin, CEO of vibrating screen specialist Kwatani. “Once equipment is operational, however, OEMs still need to make sure that their equipment provides the lowest total cost of ownership.”

Meeting all the necessary performance criteria means both the process ‘duty’ requirements – managing the required throughput and product – as well as the structural and mechanical demands of durability, ease of maintenance and reliability.

Kwatani’s extensive in-house technical capacity to custom design and manufacture vibrating screens for a range of different applications allows it to align its equipment not only to closely meet the customer’s process requirements, but also to accommodate the existing plant infrastructure.

“We work closely with the EPC or the mine on the interface between the infrastructure and our equipment,” she says. “This may involve optimising the dynamic loading of a screen, taking into account the features and capacity of the plant structure, to avoid costly and time consuming plant modifications.”

It may even extend to offering advice on resonance issues where there are a number of vibrating screens operating in close proximity. The company’s experts have also been requested on occasion to assist with an appropriate chute design, which can influence the performance and life-span of the screen.

“At Kwatani, we are keenly aware that engineering costs on a mining project must be contained at every opportunity, so we minimise the impact that our equipment has on the number of hours that an EPC must invest in project engineering and implementation,” says Schoepflin. “We work to accommodate the client’s plant design by matching the footprint of our machines to those constraints wherever possible.”

She emphasises that this kind of adaptation is only possible with custom designed equipment, which is a key factor in Kwatani’s focus on engineered solutions rather than off-the-shelf products. Schoepflin also highlights reliability as non-negotiable when it comes to meeting project deadlines, as tight schedules are usually the order of the day in any capital project.

With an extensive reference base across the mining sector, Kwatani has recently constructed a heavy-duty grizzly feeder and a sizing screen for Vedanta Zinc International’s Gamsberg zinc project near Aggeneys in the Northern Cape. Another recent contract will see the company delivering six large screens to Pan African Resources’ Elikhulu gold retreatment plant at Evander.

HEAVY KWATANI SCREEN FOR GAMSBERG

Spartan-based vibrating screen specialist Kwatani, driven by its aggressive cost leadership strategy, is supplying a large exciter-driven grizzly feeder and a sizing screen to the Gamsberg zinc project near Aggeneys in South Africa’s Northern Cape Province.

As the flagship of miner Vedanta Zinc International/Black Mountain Mining, Gamsberg is set to exploit one of the largest known, undeveloped zinc ore bodies in the world, with SA-based ELB Engineering Services conducting the engineering, procurement and construction (EPC) services.

Kwatani was contracted to supply a heavy-duty grizzly feeder capable of feeding over 750 tonnes per hour of ore. Built with cast manganese grizzly bars for durability, this robust unit will withstand maximum lump sizes of up to 1,5 metre in size. Also supplied is a single-deck, motor-driven sizing screen of the same throughput capacity.

“Kwatani has a significant reference base especially in the Northern Cape, where we supply most of the mining vibrating screens,” says Kwatani CEO Kim Schoepflin. “Our installations are particularly well recognised in those areas with arduous applications.”

While price was a key consideration, Schoepflin highlights the customer’s insistence on robust equipment that is fit-for-purpose. Kwatani has been able to meet the project’s tight roll-out schedule, not just with the delivery of equipment but with all the necessary product documentation that will facilitate compliance and safe installation.

“We have completed our part of the project, and are ready to commission the equipment in line with the overall plant construction schedule,” she says. “We also assisted our client with the design of the chute that will feed the grizzly.”

After fabrication, the equipment was fully tested on Kwatani’s in-house test bench at its 17,000 m2 facilities near OR Tambo airport.

The supply of the equipment will come with an extended warranty which will include regular visits by field experts from Kwatani’s fully-fledged branch in the Northern Cape. The capacity of this facility will allow it to conduct both the commissioning of the equipment and the follow-up inspections and interventions.

GROUND RULES FOR REDUCING MAGNETITE LOSSES IN DENSE MEDIUM PLANTS

While the evolution of dense medium separation (DMS) technology has seen various advances since the mid-1900s, there are still a number of “fundamentals” that will allow users to reduce magnetite losses over the life of a DMS plant.

Speaking shortly after the Southern African Coal Processing Society’s biennial conference in Secunda recently where Kwatani, represented by Jeremy Bosman, presented a paper addressing the impact of appropriate screen selection on dense medium recover and highlighted the importance of adhering to certain ground rules.

“Across the different processes, there are basic principles that are common, such as the use of drain and rinse screens to recover magnetite from the product and reject streams,” says Kim Schoepflin, CEO of Kwatani.

She says a concentration of magnetite in the dilute medium must also be achieved to give a suspension of high relative density, or overdense, medium using wet drum magnetic separators.

Schoepflin outlines the fundamentals to be observed in restricting magnetite losses, regardless of which screening arrangement is chosen.

“The feed arrangement onto the screen must ensure that the full width of the screen is utilised,” she says. “Low feed velocities are also critical, as this maximises the drainage rate on sieve bends and multi-slope screens.”

She emphasises that the drain section, which includes both static and vibrating screens, must have sufficient area to recover 95% of the medium being fed to it, and that allowance must be made for potential blinding which will reduce the open area of the screen.

“It is vital to take the average particle size and bed depth into account when selecting the screen width,” she argues. “Running at too high a bed depth will increase medium carry-over from the drain to the rinse section, and will also reduce the efficiency of the rinse water in washing off the medium; this in turn will lead to an increase in magnetite losses.”

Another important aspect to observe is that sufficient rinse water must be used to wash off the adhering medium, without overloading the wet drum magnetic separators. Provision must also be made at the end of the screen – after rinsing – for the clean coal and reject material to dewater before being discharged off the end of the screen, says Schoepflin.

LONGEVITY AND LOW OPERATING COSTS MAKE KWATANI IDEAL FOR IRON ORE OPERATION

A cost leadership strategy driven through continuous product improvement and the on-going optimisation and streamlining of its engineering and production facilities have seen Kwatani screens maintain their reputation for robustness and longevity, while being cost competitive.

Jan Schoepflin, general manager sales and service at Kwatani, previously Joest South Africa, says this is one of the primary reasons why an iron ore operation in the Northern Cape placed an additional order on the company for 24 of its vibrating screens.

“Being cost competitive is not just about the capital purchase price, it is actually about the owning and operating costs of equipment,” Schoepflin says. “To Kwatani, this is about producing a quality product at a marketed related cost that will achieve the highest throughout with the lowest total cost of ownership.”

Kwatani has gained a reputation as a vibrating equipment solutions provider and not just an equipment supplier. Schoepflin explains that the company’s technical team offers a depth of expertise and experience that is largely unmatched in the mining sector.

“Our modus operandi is to spend time with the customer so that we understand specific plant conditions and application requirements. This investment is essential as it also allows for the flexibility needed to provide a vibrating screening solution that takes both the capital outlay as well as the operating cost into account,” he says.

Kwatani has a strong relationship with this customer built on the back of the successful operation of its vibrating screens on the plant for decades. The vibrating equipment replacement programme saw 100 Kwatani screens installed across the plant in recent years.

The order for the 24 new vibrating screens will complete the plant upgrade. The first two orders were for a combination of double and single deck machines, while the latter were all for single deck screens. All screens are 2,4 metres wide with a length of 4,8 metres.

Retrofitting vibrating screens does require a dynamic approach, and Schoepflin says that in this instance Kwatani engineered a solution whereby the bottom sections of the previous existing screens were used as counter balance frames. This, he says, will reduce the dynamic loads into the existing structure where these replacement screens will be installed. In addition to this, it saved costs as there was no need to manufacture new counter balance frames.

“The existing sub frames were closely inspected for structural integrity to ensure that these would be able to handle the load, and this is all part of our overall approach when working closely with customers on retrofit projects such as this,” Schoepflin says.

All the Kwatani vibrating screens being supplied are exciter driven, and a significant aspect of this turnkey project was that the customer specifically requested Kwatani gearboxes.

Derrick Alston, director at Kwatani, says that majority of the vibrating screens operate in very wet conditions with high humidity which makes a mechanical driven system such as a gearbox the preferred option.

Locally manufactured Kwatani gearboxes are known for their robust construction and reliable performance even under the harshest operating conditions. These components are produced at Kwatani’s facility in Spartan under stringent quality control conditions. The company is ISO 9001 accredited.

Delivery of the screens will be phased with the first three already delivered and the last unit scheduled for delivery in December 2017. This turnkey operation includes the supply of peripherals and piping, and on-going support will be provided by Kwatani’s service centre in Kathu.

“Having an established presence in Kathu is a major advantage to all our customers in the region, and ensures that the highest levels of support can easily be maintained,” Schoepflin concludes.

A Kwatani scalper screen being installed for an iron ore application.

VIBRATING SCREEN MAINTENANCE NEEDS COLLABORATION, NOT A CATALOGUE

Cost pressures often force mines to make difficult decisions about how they approach the maintenance of their vibrating screens; OEMs can ease the trade-offs by offering solutions that match customers’ specific needs and resources, according to Kwatani CEO Kim Schoepflin. The OEM was previously known as Joest.

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