AngloCoal has awarded the contract for a 60tph fine coal flotation plant at Greenside Colliery to Dowding, Reynard & Associates (DRA).

The contract, valued at R30M, was awarded in September last year and is expected to boost coal production from the colliery by approximately 30tph of additional export product.

The flotation plant will treat the slimes from three existing dense media modules originally built by sDRA. Construction commenced at the end of October 2003 and commissioning is targeted for the end of June this year. The plant will make use of flotation cells that have been developed by AngloCoal. Slimes from two existing thickeners will automatically be diluted to the correct slurry density and distributed evenly to four sets of multi-cells. Mass flow will be measured, and collector and frother dosing added at a controlled rate for consistent, optimal flotation performance. Instrumentation on the flotation units will allow automatic control of the mass pull and product quality.

Flotation concentrates gravitate to a surge tank/thickener. The tails gravitate to a tailings thickener and are pumped to the existing tailings disposal system. Flotation concentrates are dewatered with spiral plant product using solid bowl centrifuges. The centrifuges are fitted with variable speed main drives and scroll drives, allowing the facility to optimise throughput and final product moisture. To avoid problems associated with reagent contamination, the flotation plant water circuit is independent of the water circuits in the dense medium plants.

Many of DRA’s clients are repeat clients and, in line with the company practice of developing long-term relationships with its client base, this contract is the fourth DRA has undertaken for Greenside Colliery in the past few years. “Our philosophy when tendering and designing plants is to focus primarily on efficient operation, as low operating costs generally have a greater impact on life-cycle costing than initial capital investment”, says Mike Salter, senior process engineer. “We use our significant experience to deliver a technically competent plant at a competitive cost, within or ahead of schedule.”