A coal waste management system handling 7000 tonnes per hour at a coal mine in South Africa.

Many industrial facilities, mines and power stations rely too much on dust suppression and extraction systems, when the real answer is to improve the flow of material through well-designed chutes. This is the opinion of Weba Chute Systems technical director Alwin Nienaber, based on decades of experience in this field. 

His view is that 50% to 80% of the dust problem around conveyors and transfer points can be resolved by applying the right chute system design and positioning equipment correctly.

Bifurcated chute in operation for the past 23 years at a coal mine in South Africa. 

“Many of the dust suppression and dust extraction systems that are applied in these applications are expected to do more than they are capable of,” says Alwin. “A preferable approach is to get the chute design right first, and then apply these other systems to deal with the residual dust load.”

Material discharge onto conveyor showing centralised belt loading.

Waiting to settle

He explains that the advantages of doing so extends well beyond health and safety benefits. He has seen more than a few situations where the dust created by a poorly-designed chute can prevent personnel from moving or working in that area. This often prevents the checking or maintenance of critical equipment during operating hours, requiring more downtime to wait, literally, for the dust to settle.

“In such examples, excessive dust can reduce an operation’s efficiency, so there is an opportunity to improve overall productivity by fixing the dust problem,” he adds. “Other equipment in these areas also gets heavily coated with dust, and needs regular cleaning to ensure optimal performance. Cleaning becomes yet another avoidable cost.”

The Weba cascade system.

Lack of control

To address excessive dust creation, a good chute design is based on understanding the physics of material flow, and avoiding uncontrolled velocity and impact. A lack of control over the way material flows will degrade the material and create higher levels of aeration is what leads to dust dispersal. 

“Our philosophy is to ensure that material flows more easily and remains consolidated as a homogenous stream,” Alwin concludes. “We base our designs on the ‘supertube’ effect, which also allows the controlled transfer of material onto the conveyor belt. Not only does this reduce dust, but it also cuts down on the wear rate of the belt itself.”


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