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Solvent extraction of nickel and cobalt

Solvent extraction with advanced Outotec VSF® System gives superior operational results compared with conventional systems. It ensures maximum recovery of high-grade metal product.

In the solvent extraction phase of the process, incoming pregnant leach solution (PLS) is concentrated and purified, and a pure electrolyte is then used in electrowinning to produce chemically and physically high-quality product.

For nearly 30 years, Outotec has been developing its wide range of solvent extraction technologies, delivering both equipment and processes to its customers in the metals processing industries. This long history of dedicated research and development began in response to increasing demands for lower operation and investment costs, together with more reliable and stable production where health and safety issues are given high priority in plant design.

The results have been impressive, and today the plants that use the ground-breaking Outotec VSF® (Vertical Smooth Flow) mixer-settler technology are among the most profitable in the world. Since launching the VSF® technology for copper applications more than a decade ago, Outotec has gained a leading market share of new copper solvent extraction capacity.

The main benefit of the VSF® technology is that minimal entrainment levels can be achieved without compromising reaction and settling rates. The use of the Outotec settler design together with the novel VSF® pumping and mixing technology ensures a high specific settler throughput with low entrainment values. The Outotec DDG® picket fence design allows a thick and dense dispersion layer at the front end of the settler. This dispersion band filtrates small droplets and ensures low entrainment values.

Low entrainment brings value in terms of

  • Low investment costs, due to smaller settler sizes and less organic inventory
  • Low operating costs, due to low copper and reagent losses
  • Flexibility, enabling constant cash flow during varying leaching conditions

Fire safety

Solvent extraction with Outotec VSF® design includes the following precautions to reduce the risk of inflammability:

  • Smaller settler sizes and less organic inventory due to the Outotec settler design and VSF® technology
  • Low velocity of the solution transported through the pipelines and low agitation rate for decreasing the risk of static electricity emergence
  • Low surface temperatures of electric motors and speed reducers
  • Covering of all tanks with hoods to decrease the possibility of evaporation
  • Maintaining 100 % filling of pipelines

Outotec recommends the Marioff Hifog fire extinguishing system for solvent extraction plants. The Hifog system is based on high-pressure water mist and is not harmful in the organic phase of a solvent extraction plant.