In a compact and congested transfer point area in a Limpopo platinum mine’s screening house, Weba Chute Systems recently applied its transfer point experience to smooth out the operation.

According to Hilton Buys, regional manager at Weba Chute Systems, there had been an ongoing issue with fines spillage and skew belt loading from two conventional chutes. The chutes transferred fine material of minus 25 mm in size from the screen underpans to the conveyor belts.

"At the heart of the issue was a design problem, which we analysed and solved through structural modifications recommended by our in-house design office, and two new custom designed Weba chutes," says Buys. "We had long before supplied the chutes for the oversize material passing through this facility, and these chutes have been running smoothly for over 10 years."

The impact of implementing the new chutes and transfer point design was immediate, he says: no more skew belt loading and no more spillage. The belts are now running true and there is no longer any need for additional cleaning around the belts, he says.

"A key aspect of the solution was our cascade chute in a horse-shoe formation," he explains. "Our chute manipulates the material to stay in the centre as it leaves the chute."

Also, the chute design considered all the material characteristics like lump size, moisture content and bulk density, so the velocity of the material leaving the chute could be controlled. This allows the material to leave the chute at the same speed that the conveyor is travelling.

"By doing this, we did not need to have skirting as the material is kept in the middle of the belt," he says. "Neither did we need to install impact idlers, as the material was not dropped from a height; rather, there was a gentle transfer from chute to conveyor, which moved at comparable speed."

He argues that the focus in mineral processing plants is generally on relatively capex-intensive equipment like crushers, screens and apron feeders. Too often, however, the vital role played by chutes and conveyors in moving ore is ignored.

"It is a serious mistake to overlook the importance of a correctly designed transfer point," he says. "The problems that an inadequate design can cause are costly to the whole operation, and also have safety implications."