CSA Copper Mine gains significant benefits from flotation partnership

CSA Mine is an underground copper mine located in Cobar, Central Western NSW. Employing more than 300 people, CSA Mine is operated by Cobar Management Pty Ltd (CMPL) – a wholly-owned Australian subsidiary of Glencore International AG (Switzerland). CSA Mine extracts over 1,100,000 tons of copper ore and produces in excess of 180,000 tons of copper concentrate per annum. This concentrate is exported to smelters around the world.

Partnership Approach

The project, involving replacement of 30 existing scavenger flotation cells at CSA, was already underway when Outotec Services personnel became involved, in a team led by Peter Gillies, Project Manager, Outotec South East Asia Pacific.

“When I arrived on the project it was clear there was a lot to do before it could progress. Mid-December was our deadline and in April, when I started, we had our metallurgical production criteria, but had a lot to finalize, including the scope of works,” explains Derek Beehan, OreProcessing Superintendent at CMPL.

As CMPL and Outotec had already worked together in the past, most recently when Outotec replaced a thickener on a lump sum turnkey basis in 2005, it was recognized early that a collaborative, partnership approach would again benefit the project. This approach would deliver not only processing benefits, as the replacement flotation technology was state of the art – but equally importantly, a collaborative approach ensured open communication, with all parties having greater ownership in the project.

Expanded scope

Originally, Outotec was to replace aging scavenger cells in the flotation circuit with new Outotec TankCells (3 x TankCell 30s). Although the flotation circuit at CMPL incorporated equipment from other suppliers, flotation technology from Outotec was chosen for the upgrade.

Outotec TankCells are renowned in the industry for their performance, ease of operation, and reduced power and air consumption. This initial scope developed into a far more comprehensive supply, with CMPL soon requesting that Outotec supply engineering, design, installation and commissioning of the cells, plus additional ancillary support (instrumentation, external launders, and some piping).

Challenges

Concrete foundations were initially planned for the footprint, however they proved too costly. The most cost effective solution was to upgrade the existing steelwork for the cell installation. This change from civil to structural steel supports came late in the project, meaning that certain site elevations and dimensions were only confirmed six weeks prior to install so detailed planning and a dedicated teamwork approach was essential. The upgrade was further complicated by a limited footprint and also the layout of the installation, as demanded by the process.

“It is always tight working indoors in a mill environment – and here temperatures were up around 38 – 40 degrees,” said Mr Beehan. “Dust, confined space, and working in an operational environment made it difficult at times. So good teamwork, clear communication (and a sense of humor), and a group focused on achieving our goals were required.”

Further challenges arose due to factors such as limited crane access. The flotation cells, for example, had to bedesigned in sections no heavier than two tons to facilitate an overhead travelling crane. The restricted footprint also imposed a maximum height – thereby affecting not only the cells but also the support steelwork for the cells.

An appropriate design was also required from a maintenance perspective – ease of serviceability being a key consideration.

Results and benefits

Installation commenced mid-October 2010 and was completed by the end of December 2010, with commissioning early 2011. The installation was offline of normal production, apart from a tie in to the existing plant when the cells were dry commissioned. “Outotec pulled out all the stops to help CMPL meet its objectives – it was a big ask to bring it in on time – but this was achieved,” said Mr Beehan.

“The biggest benefit for CMPL is the reduced risk in cell structural failure causing unplanned downtime. Also, due to a more stable control system, we can accommodate the fluctuations in our feed grades and throughputs that we experience in the plant.

“Another big benefit is energy savings. We are using three 45 kW motors with the new technology, versus 15 motors drawing a total of 225 kW previously. We’ve saved ourselves nearly 90 kW (40%), which is very important.”

Furthermore, the site experienced significant savings on maintenance, with the 30 existing scavenger cell mechanisms replaced by only three Outotec mechanisms. Spare part costs have also been significantly reduced and there has been no unscheduled maintenance required on the new TankCells.

Since the time of the installation, copper feed grade decreased from an average 4.9% in 2010 to an average 4.0% in 2011. Both the overall copper recovery, at 96%, and the final concentrate copper grade remained constant, despite the lower feed grade. This is a significant result, indicating an improvement in circuit stability and performance. Copper recovery is also expected to improve when the copper feed grade returns to 2010 levels.

Conclusion

The close partnering relationship between CMPL and the Outotec Services team produced clear benefits in overcoming initial challenges and delivering a key project on time and on budget.

*This case study has been written prior to the merger of Metso and Outotec.