Float cell breakthrough

A Wemco Smartcell has been integrated into the tailings line at Stratford Coal.

A Wemco Smartcell has been integrated into the tailings line at Stratford Coal.

The first installation of its type in the Australian coal industry, the cell has increased saleable product by some 60,000 tonnes per year.

Primary fine coal processing at Stratford is through two Jameson Cells. Variations in the overall quality of the feed into the Jameson Cells were resulting in significant variations in fine coal yield and the decision was taken to investigate the tailings for coal content.

The investigation project, which saw FLSmidth Minerals (Dorr-Oliver Eimco) install a 6m3 pilot cell to scavenge coal from the Jameson Cells tailings, was initiated by Stratford Coal’s CHPP Manager Tony James.

“We were keen to ensure we were maximising the output from the processing circuit,” said Tony, “The pilot trial results, which proved very successful, gave us the detail of the float cell we would require and the subsequent cost-benefit analysis was sufficient encouragement for us to take the next step — installing a specially-designed float cell into the tailings line.”

The cell installed at Stratford is a 130m3 Wemco SMARTCELL, designed and engineered by FLSmidth Minerals. Already well known in the hard rock processing sector, the cell at Stratford would be a first for float cells in coal tailings processing.

The Smartcell combines a near-surface, self-aspirating rotor with a false bottom/draft tube arrangement which eliminates blowers from the cell — a configuration which, according to design engineers, means cost savings and the highest slurry circulation rates in the industry.

The cell also incorporates bevelled bottom tanks for improved slurry circulation and suspensions, along with radial and peripheral launders and baffles to stabilise the froth surface and increase grade and froth transport rate – design improvements proven to improve overall efficiency and productivity.

Installed and commissioned at Stratford in October 2007, the cell has increased overall fine coal yield by some 2% – which is giving the mine an additional 60,000 tonnes per annum of saleable product.

The introduction of the new float cell has also meant other benefits for the fine coal processing circuit at Stratford.

According to Tony James, the Smartcell has cleaned-up the overflow on the tailings thickener, which has meant big benefits for the complete clarified water circuit. It is also actively removing any residual frother from the tailings, which had been causing cavitation within the pumps in the tailings co-disposal system.

The Smartcell’s ability to remove residual frother has meant that Stratford can increase the dose of frother into the Jameson Cells, increasing the efficiency and output of the two cells.

“Installing the float cell has made the whole processing and disposal circuit much easier to manage and more profitable,” said Tony James.

“The results are much better than we expected: certainly the increase in saleable product was predicted but also the upstream and downstream operational improvements the new cell has given us.”

Jeff Euston

FLSmidth Minerals

02 4320 4700

jeff.euston@flsmidth.com

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