Mechanical Technology September 2015

⎪ On the cover ⎪

Above: ThyssenKrupp’s most current success, a state-of-the-art ThyssenKrupp tandem rotary tippler at the Port of Nacala. These systems require deep bunkers underneath the rotary tippler to accumulate the material. Left: Rotary tipplers are designed so that the turning point coincides with the axis of rotation of the wagon couplings in the tippler. Right: Side tipplers are the simplest random tippler option.

Positioners and clamping Before tippling, the wagons need to be accurately positioned into the tippler so that they can be securely clamped and safely rotated. A positioner fitted alongside the railway line performs this function. A hydraulic arm swings down onto the wagon couplings between wagons and pushes the train or the rake of wagons along the track, moving the empty wagons out of the tippler and the following loaded wagons in. “Modern positioners are driven on a rack and pinion system by a hydraulic or electric drive. These systems move the entire train and position the wagons to within a centimetre,” Tellier informs MechTech , “and this is all done automatically with the positional accuracy being ensured by an advanced control algorithm and feedback sensors”. “Multi-body dynamic simulations are used to correctly size the positioner drives and to optimise the positioner control algorithm,” he says. Once positioned, the wagons are locked onto the tippler using a clamping system. “We are globally renowned for our hydraulic clamping system, which is a lightweight, flexible and efficient modern system, but gravity clamping has become preferred in South Africa – and as world leaders in tipplers, we can offer gravity clamping solutions just as easily,” Göing assures. Gravity clamping works off mechanical linkages and coun‑ terweights, which cause clamps to lock onto the top edges of the wagon as soon as the tippler begins to rotate. Showing a Scada image on a wagon tippler, Tellier points out the feeder bins underneath a rotary tippler. “Each tip‑

– two wagons hard coupled together with a rotary coupling between each pair. This arrangement allows for tandem tippling, where two hard-coupled wagons are unloaded simultaneously,” says Tellier. At the Majuba power station, one of Eskom’s largest power plants (4 110 MW) and one of the few without its own dedi‑ cated coalmine, a random rotary tippler is being used to accommodate rail delivery of 0.42 Mt/month (14 000 t/d) from coalmines in Ermelo. A further 0.74 Mt is delivered less efficiently by road, us‑ ing approximately 700 trucks per day. “Trucking is currently necessary because of the inadequate railway infrastructure to power stations, but it does not help the overall efficiency and productivity of our plants,” Göing suggests. Rotary tipplers are designed so that the turning point coincides with the axis of rotation of the wagon couplings in the tippler. “These systems require deep bunkers underneath the rotary tippler to accumulate the material. Both single and tandem rotary tipplers are available, depending on throughput requirements and coupling arrangements on the unit- trains,” he explains. Adds Göing: “There are two types of rotary tipplers, the O-type and the C-type. The C-type design has an open‑ ing to the one side to allow the wagon positioner to pass through the tippler unhindered. If using an O-type tippler, the wagons need to be pushed into and out of the tippler from further up or down. There is a small time savings associate with a C-type tippler, because the positioner can operate closer to the wagons being pushed into the system.”

ping action is depositing 80 t (single) or 160 t (tandem) of material into the bins below, and you want to make sure that the material is able to flow smoothly and continuously onto the conveyors and that the bulk does not hammer directly onto the vibratory, apron or belt feeder below. So the levels of the bins and the belt loading rate is carefully controlled to optimise material flow and to best match the wagon unloading rate,” he explains. The ore from the wagon tippler is channelled into separate bins below the system, and the level of each of these is carefully monitored – typically by using 3D radar measuring technology from Indurad – and automatically controlled to balance the output flow with the batch unloading of the wagons. “These systems can deliver at 6 500 t/hr, so several feeders are required to match the unloading speed and remove the material fast enough,” he adds. “We are a local OEM capable of de‑ signing and manufacturing entire wagon tippler systems – the tippler, positioners, bins, apron feeders and conveyors – to smooth the flow of material while al‑ lowing wagons to be emptied as fast as possible,” says Göing. “And in addition to ThyssenKrupp’s wagon tippler offering, we can offer solutions from the mine stockyards and load-out stations, through the rotary tipplers and all the way to the stackers, reclaimers and ship loaders. Our modern solutions enable efficient transportation of bulk materials that can significantly improve the competitiveness and long term sustainability of local mining opera‑ tions,” he concludes. q

Mechanical Technology — September 2015

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