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Outotec Vane Feedwell in more than 50 installations worldwide

At the end of 2008, Outotec launched a high-performance feedwell designed to significantly increase efficiencies in thickening and clarifying applications. Since then, in an industry where success is often measured over decades, Outotec’s Vane Feedwell has been well received, with more than 50 installations spanning 17 countries in just over a year.

Efficiency improvements can be significant. One particular site, after a retrofit of a 7m Vane Feedwell, reduced flocculant costs by 20%, while improving underflow density by 2% w/w, says Outotec Global Technology Manager for Thickening, Brandt Henriksson.

“The technology is the first major industry innovation in thickener feed systems since self-diluting systems such as Outotec’s Autodil were introduced in the 1990s. This feedwell enables thickeners at higher unit area throughput and has measurable process advantages, especially at feedwell diameters of 4m and greater.”

The Outotec Vane Feedwell – incorporating seven global patents – is the result of many years of internal research and rigorous site testing, followed by Computational Fluid Dynamics (CFD) analysis by CSIRO.

The technology has since been applied in 53 applications in diverse nations including Australia, Brazil, Canada, Chile, Finland, Ghana, New Zealand, South Africa, Peru, Russia and Sweden. Benefits can include

* Reduced plant operating costs
* Reduced flocculant consumption
* Increased underflow density
* Higher solids throughput
* Improved water recovery and clarity
* Increased reagent/mineral recovery
* Stable operation and less downtime

The design is suitable for both greenfield installations and also retrofits and is now the global standard for Outotec thickeners,” said Henriksson.

One of the main design features of Outotec’s Vane Feedwell is the interconnected upper and lower zones. The upper zone, into which feed, dilution water and flocculant are added, provides enhanced mixing and energy dissipation.

This maximises flocculant adsorption, eliminates the possibility of coarse/fines segregation and ensures all particles are aggregated together by the flocculant. Efficient operation is maintained in this upper zone over varying feed rates.

The lower zone promotes gentle mixing for continued aggregate growth, with the option for secondary flocculant dosing. This zone also enables aggregates to uniformly discharge under low shear conditions.

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