Streamlined coal supply is vital for South Africa’s power stations, so Weba Chute Systems is designing over a dozen replacement chutes for a Mpumalanga coal mine. The mine has been experiencing considerable downtime due to the high maintenance of its existing conventional chutes but needs to deliver on its power station contract.
Weba Chute Systems is currently busy with designs that will pave the way for the retrofitting of over a dozen chutes at the mine. Eight of the units are silo discharge chutes, transferring coal from the colliery’s run-of-mine feed to its coal processing plant. Another four chutes are to be replaced in the plant itself, while there is another chute located between two related feed conveyors.
“The main objective of the new bespoke chutes is to ensure stable supply to the plant, and from there to the nearby power station,” says Dewald Tintinger, Weba Chute Systems’ technical manager and designer. “The existing equipment is demanding too much maintenance, leading to unacceptable levels of downtime.”
Designers discussing the flow design of the transfer chute. Image credit: Weba Chute Systems & Solutions
The key to improved uptime and extended chute lifespan is the company’s flow control principles in its designs. The chutes in the plant, for example, must deal with oversize material of between 150mm and 500mm in size. “Handling these large particles, chutes are exposed to high levels of impact and wear,” says Tintinger. “With the controlled flow philosophy of our Weba ‘cascade’ chute system, we control both the velocity and the impact.”
Commenting on other aspects of the custom designs, Tintinger says the transfer points will include features such as dead-boxes which create a lining from the mined material itself. This reduces the wear on the chute’s metal surfaces, extending the maintenance intervals and delivering more uptime. He highlights that the processing plant feeds the power station directly through two overland conveyors. “This is a highly efficient model for delivering coal, but it demands that all elements of the materials handling system are working together,” he says. “Any disruption of coal flow caused by a transfer chute can cause costly delays and render coal delivery unreliable.”
Designer taking manual and 3D laser scanning measurements on site. Image credit: Weba Chute Systems & Solutions
He notes that the mine has had good experience from the many other Weba chutes already installed at this operation and is now standardising on this internationally accepted transfer point design for better results. Designs and engineering are conducted in-house by Weba Chute Systems’ experienced team, using the latest software and finite element analysis tools for testing.
The design work is expected to be completed around the middle of 2022. Thereafter the mine will be in a position to contract the fabrication and installation work.