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 South African platinum mine processing plant and smelter situated in the Bushveld Region, within the Limpopo province
It is being processed from platinum group metals (PGMs), chrome and base metals. The material is extremely sticky, similar in constitution to clay and needed to be transferred into a dryer. In addition, this material was to be received from mines within the immediate area and also from mines in the Mpumalanga province of South Africa, around 300km away.
During the transit period, the plant had found that some composites dried out, while others remained wet. The gears required for the feeder would be large-scale, posing some practical challenges when it came to physically fitting into the unit synchronisation without the screws clashing. Larger gears would also substantially increase the costs of the wet screw feeders and easing of maintenance was a further requirement by the plant. The throughput needed from the first wet screw feeder was between 30 and 40 tonnes per hour, with 15 tonnes per hour required for the second feeder.
For application testing, DryTech built a trial machine and a three-screw shaft solution was found as most effective. While the three screw shafts were mechanically linked to one other during this trial, the client favoured a solution with independent shafts, using the preferred Danfoss FC 302 22kW units controlling a 22kW motor/gearbox on each shaft, with electronic synchronisation between them. All three shafts needed to rotate in a co-ordinated manner to help prevent mechanical damage. If any of the shafts go out of synchronisation, the machine must be stopped.
According to DryTech, the motors are mounted above the gearbox driving each screw shaft, which means that the motor drives the gearbox via a belt drive. The results showed tighter speed and operation control.
Danfoss, in support of BMG Electronics, has helped to assist DryTech International for use by a South African platinum mine processing plant and smelter situated in the Bushveld Region, within the Limpopo province.
