MechChem Africa September-October 2021

Conveyor innovation for platinum processing plant Danfoss, in support of engineering components provider BMG Electronics, an authorised DrivePro ® service partner, has helped to assist DryTech International in its development of a unique wet screw feeder for use by a local platinum processing plant and smelter in the Limpopo province.

Left: Riaan van Niekerk, DryTech. Centre: Stephen Brown, Danfoss. Right: Mick Baugh, BMG.

D ryTechprovides innovativedesign solutions for thermal processing problems, successfully develop- ing a variety of complex thermal processes ranging from mineral concentrate flash dryers to high-temperature reduction kilns and continuous vacuum dryers. The company recently developed a wet screw feeder for a platinumprocessing plant that was having to deal with unusual char- acteristics of the material being processed from platinum group (PGMs), chrome and

base metals. The material is extremely sticky, similar in constitution to clay, and needed to be transferred to a dryer. In addition, this material was received not only from mines within the immediate area, but also frommines in theMpumalanga province, a distance of over 300 km away. The plant found that, during the transit period, some composites dried out, while others remained wet. From a mechanical design perspective, the gears required for the feeder would

be large-scale, posing some practical chal- lenges when it came to physically fitting them into the unit without the screws clashing. Larger gears also substantially in- crease the costs of wet screw feeders. Ease of maintenance was a further requirement by the plant. The throughput needed from the first wet screw feeder was between 30 and 40 t/h, with 15 t/h required for the second feeder. A trial machine was built by DryTech for testing the application and a three screw

For the DryTech wet screw feeder a critical requirement was that all three shafts needed to rotate in a co-ordinated manner to help prevent mechanical damage. A Danfoss VSD solution was therefore adopted.

22 ¦ MechChem Africa • September-October 2021