FLSmidth said four of its 3.8 metre disc filters, each comprising 14 vacuum discs, will prepare tailings slurry for the backfill application at the DRC project.

The filters have been installed in two modules, with two units in each, as part of a dewatering strategy aims to create a cake dry enough to be mixed with cement and other additives before being conveyed underground to be placed in mined-out workings as backfill.

"The efficacy of the vacuum filter in this application allows the mine to consistently achieve its targeted level of dewatering," said Howard Areington, general manager projects and account sales at FLSmidth. "This, in turn, means that the amount of cement and additives can be optimised, keeping operating costs down."

Areington said his company's product was the most cost-effective form of vacuum filtration per square metre of footprint.

Ancillary equipment included a liquid-ring vacuum pump with capacity to pump almost 15,700 m3/h at a pressure of 67 kPa, as well as filtrate receiver and a filtrate pump of 32 m3/h capacity. FLSmidth also supplied a 1060 gallon snap air receiver, a 750 kPa air compressor, a plant air receiver and an air drier.

The water used in the filter vacuum pump needs to be potable so it was important for the design to recycle as much as possible. It is therefore recirculated through a closed circuit, with a cooling tower added to dispel heat from the water before it is re-introduced to the system.

"With disc filters delivering a drier product with more water savings, FLSmidth has provided this technology to many projects around the world," says Areington. "With FLSmidth's global reputation in the field for vacuum filtration backfill applications, we have secured a significant portion of this market - also supplying some of the largest vacuum disc filters in use today."