Modern Mining: Featured News

Leading vibrating screen expert Kwatani is supplying one of South Africa’s biggest coal mining operations with 44 screens and feeders. The contract is probably the biggest of its type to have been awarded in South Africa in recent years and the biggest ever secured by Kwatani. A number of the screens boast widths of up to 4,3 m.

The vibrating screens and feeders are for a new coal treatment facility that will produce an added coal fraction destined both for local consumption and export, and which will rely on expanded rail provision by Transnet.

Kwatani PIC 01

The pride and joy of Kwatani, the 4,3 m wide scalper exhibited during a recent open day at Kwatani’s premises.

“The size of the order demonstrates not just the faith that the customer places in our custom-engineered products but also the capacity and expertise that resides in our business and extensive facilities in Spartan,” says Kwatani CEO Kim Schoepflin.

The total order includes two large double-deck run-of-mine screens measuring 3 m wide by 9 m long and three 2,4 m by 6 m degradation screens which will be installed in the mine’s drum plant. Kwatani is also supplying 20 screens and three feeders for the cyclone plant, including five 3 m wide by 7 m long desliming screens.

Among the largest units are the drain and rinse screens; four of the 16 supplied machines boast dimensions of 4,3 m by 7 m. In a further indication of scale, each of the units is driven by two large gearboxes which deliver a centrifugal force of over 460 kN each.

The company’s capability allows it to handle contracts of this magnitude while continuing to service all its customers to the level that they expect, says Schoepflin.

“Compliance to the mining charter is also increasingly important in the coal sector, and Kwatani – as the first and only vibrating screen company to meet and exceed charter requirements coupled with a BBBEE Level of 3 – offers this assurance to stakeholders as well as contributing to our customers’ BBBEE points when they tender for local coal supply contracts,” she says.

The company was also able to offer the customer an attractive commercial package, according to Kenny Mayhew-Ridgers, Kwatani’s Chief Operating Officer.

“We were able to cover all the bases for the customer, from design and fabrication to engineering and commissioning – all conducted within a strict framework of ISO quality standards,” he says. “With our commitment to engineering for tonnage, we ensure that our machines are robust and built to last – while doing the duty expected by the customer with minimum downtime.”

Kwatani’s 17 000 m2 premises in Kempton Park near Johannesburg includes modern facilities for fabrication and assembly, as well as repair and testing facilities for vibrating equipment including exciter gearboxes and electrical motors. It has 160 tonnes of combined crane capacity and extensive warehousing.

“To allow us to produce this number of machines over a relatively short period of time, we rely on a well-managed and highly efficient internal logistics system and supply chain,” says Schoepflin. “This is especially important when there are so many different machines in the order, each with its own specifications and requirements. In this case, we were dealing with over a dozen variations or machine types – adding to the complexity of the materials management process.”

She also highlights the extensive testing process that each machine and exciter drive undergoes before being dispatched and commissioned.

“Our test bench must be built up specifically for each type of machine, where they must run optimally for respective periods of about an hour before being passed and certificated,” she says. “As a company that specialises in custom engineering, our processes are set up to manage the production of a range of machine sizes in quick succession.”

A vital aspect of the testing, says Mayhew-Ridgers, is that readings and measurements can be taken on the test bench – such as the stroke and acceleration – to ensure that the test performance aligns with the expected parameters defined in the design. Having the design expertise in-house, which includes finite element analysis (FEA), Kwatani is able to seamlessly align and monitor the design and manufacturing processes to best effect. The FEA allows the structural and mechanical integrity of each custom design to be checked and proved on the test bench before it leaves the facility.

As importantly, this test data can be applied during the commissioning process at the mine site to ensure that the machine is performing to specification – substantially reducing the mine’s risk of any commissioning delay.

“This means that we can issue products in a perfect state, and test on the bench to check for any inconsistencies between our design parameters and our manufactured result,” says Schoepflin. “We then begin all these tests again once the machine is installed on site in a ‘cold’ condition and again under the load of real material.”

She emphasises that Kwatani’s quality control processes are an integral part of the custom-engineered focus, as each machine has to be checked against its own specific design requirements. This, in turn, gives customers peace of mind that the machines supplied are both designed and manufactured with scientific accuracy to suit their on-mine duty.

“It is also worth noting that the testing of large scalper screens is not a task that many OEMs are in a position to tackle, as it requires substantial facilities with sufficiently high levels of input power,” she adds. “Most companies can’t test this size of unit because they don’t have the requisite cranage capacity, electricity supply or specialised test facility.”

Kwatani has developed the technical capability to handle scale – both in terms of the contracts it wins and the dimensions of its custom-engineered screens and feeders. However, says Schoepflin, this does not prevent it from tackling smaller projects and treating them all with the same level of meticulous attention.

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