A pioneer in large-cell technology, which reduces capital expenditures and increases energy efficiency, FLSmidth worked closely with Rio Tinto to fast-track the project by applying a broad range of engineering, construction and commissioning expertise. The world’s largest installed flotation cells to date, the SuperCells are used in the bulk copper-molybdenum flotation circuit.
Economies of scale force flotation cells to keep getting bigger – and more efficient. Until recently, the WEMCO® SmartCell™, developed in 2003, was the largest with a capacity of 257m³. But in 2004, FLSmidth decided to take this product line to the next level and started developing a new generation of flotation cells. Based on knowledge from collaboration with the CAST group (the Center for Advanced Separation Technologies, a partnership of seven mining schools in the US) FLSmidth created the SuperCells, the largest installed flotation cells in the world, with a capacity ranging from 300 m³ to 350 m³.
To design the enormous SuperCells, FLSmidth made CFD models of existing cells and scaled them up using dimensionless and hydrodynamic analysis. The results were then verified using updated CFD models. The SuperCells can use one of three FLSmidth mechanisms – WEMCO, Dorr-Oliver® and XCELL™ – and all three are being tested at the Rio Tinto Kennecott plant's Copperton Concentrator: the 300 m³ SuperCell with the WEMCO self-aspirated top-mounted rotor, the 330 m³ SuperCell with the Dorr-Oliver conventional bottom rotor and the 350 m³ SuperCell with the XCELL forced-air mid-rotor design.
Construction without stopping production
FLSmidth, in conjunction with its newly acquired CEntry Engineering Group in Salt Lake City, was responsible for project engineering, construction and commissioning at the Copperton Concentrator. The first phase included preparing infrastructure and installing the first SuperCell which incorporates the WEMCO rotor mechanism. This phase was completed in just 110 days thanks to a close working relationship between the Rio Tinto and FLSmidth teams. More importantly, the cell was installed and brought online without stopping concentrator operation.
Next, the second SuperCell was installed with a Dorr-Oliver mechanism and brought online – and because some equipment and controls had already been installed, the plant was able to keep operating during the entire 100-day process. Finally, the team constructed three 1.5 m3 pilot cells. These run parallel to the full-scale SuperCells and each uses a different rotor so that the scale-up, mechanical designs, hydrodynamics and metallurgical performance can be compared and verified.
It’s not just the scale of the SuperCells that the project team is proud of – the project has an outstanding safety record, which is an achievement in itself. Construction work began at the Kennecott site on 1 October 2008, and FLSmidth has logged more than 70,000 man hours without a single recordable incident.
Testing and installation
In the past, cell developments have involved four-to-six months of hydrodynamic and metallurgical testing before handing over to the production team. But FLSmidth's extensive modelling and development work meant that very little onsite testing was needed.
Following installation, the SuperCells' hydrodynamics were extensively tested on water. Then they were commissioned on slurry and went into production. And right from the start, the SuperCells have produced higher than expected recoveries and grades.
To compare and test performance, each SuperCell and corresponding pilot cell is fed the same feed, operates at the same residence time and with the same operational variables. This allows a full metallurgical evaluation of the SuperCells on different types of ore, and it fully tests FLSmidth's scale-up criteria.
Bigger is better
In the case of the SuperCell, bigger is proving better. Offering lower energy consumption, improved recovery and increased operational efficiency, the world’s largest installed flotation cells are outperforming their predecessor. With commissions now in the double digits, the future is looking bright.
Project scope for the Rio Tinto Kennecott plant
• Two SuperCells
• MillMAX® pumps
• Technequip™ valves
• Control systems