Global engineering company FLSmidth has upgraded its latest-generation tailings dewatering press (TDP) system used in coal tailings applications, the company announced in December.

The new TDP design includes several enhancements, which recognise critical design considerations that make a positive difference to the belt press operation, performance and operating expenditure.

“We have now taken proven TDP technology to the next level,” says FLSmidth filtration technology specialist Jefrey Pilusa.

FLSmidth products sales manager Ricus van Reenen says that, over the years, the company has noticed competitive designs that have emulated older FLSmidth designs.

“As part of FLSmidth’s global programme and using its global resources and experience to review all our products, we decided to take another look at the belt press technology and upgrade it, with a focus on the tailings market. By offering better performance, a user-friendly design and more-cost-effective solutions, FLSmidth hopes to provide its customers with an enhanced solution as well as the company’s total service offering for its diverse customer base.”

Benefits
Pilusa says the most significant advantage of the FLSmidth TDP technology is that it offers improved cake dryness owing to its S-roll design.

Traditional S-rolls are configured in a horizontal mounting arrangement, which leads to visually discernible water pooling between the S-rolls, resulting in rewetting of the filter cake. In order to avoid the problem, TDP S-rolls are configured vertically, which means the belt travels upwards and the filtrate, which has been removed from each S-roll, goes into its own drip trays, thereby avoiding pooling and rewetting.

“This produces consistently drier cake than horizontal designs.”

Another significant advantage is increased safety and a more user-friendly design owing to the low location of the gravity drainage zone. “FLSmidth regards health and safety as one of its topmost priorities,” Pilusa says.

With the TDP design, it is no longer necessary to use a ladder or to build expensive platforms for the purpose of monitoring the gravity drainage zone, where 80% of the dewatering work takes place, as was the case with traditional designs.

“This reduces working-at-height hazards by allowing operators to inspect and monitor such critical areas from ground level,” he asserts.

Further, as with any belt press, if solids are not properly gravity-drained, the performance of the whole machine is degraded. “If the gravity drainage zone is ‘out of sight and of mind’, how can any operator do his job properly?” Pilusa asks.

Reducing the operating expenditure is always a priority. “One of the ways of doing just that is to focus on increasing the life of the belts, which is what the TDP press has done,” he points out.

The TDP design includes three unique features, including a rack-and-pinion belt take-up arrangement, which ensures that each side of the belt travels the same distance on each revolution, eliminating belt biasing and misalignment problems that lead to premature belt failures.

Secondly, each TDP frame is a built-in structure ensuring that the integrity of the unit remains as it was when it was first installed. Finally, each bearing is located with locating stops, which ensure that all rolls are parallel, both when leaving the factory and when rolls are removed and reassembled in the field. These features enhance belt life by eliminating belt biasing and belt alignment problems, while reducing maintenance costs.

The TDP technology also features a high cake discharge, which reduces installation costs, as the filter is located on ground level along with the conveyor. Other designs call for special platforms for the filters and conveyors to accommodate any discharge below ground level.

“The TDP technology obviates this additional capital expenditure, which lowers operating costs, as all areas of the filter and conveyor are easily accessible for any future planned maintenance,” Pilusa highlights.

Another advantage is that the TDP technology can be factory-assembled and delivered to site as a single unit. “The frame provides a rigid structure that will withstand maximum anticipated stresses and provide the best geometry for cloth tracking, extending cloth life,” Pilusa says.

All support bearings are self-aligning and antifriction, with triple-lip nitrile seals.

In terms of FLSmidth’s ‘One Source’ approach, Van Reenen says it can provide automated solutions ranging from panels for controlling local dewatering equipment to large plantwide control system solutions.

“We deliver state-of-the-art technology solutions for cost-effective operation and increased plant availability, accompanied by comprehensive modernisation, optimisation and maintenance services,” he concludes.