MBS has developed a new process for the recovery of copper from concentrator tailings. To demonstrate the process, MBS will build a pilot plant, which will process tailings to produce cathode copper using their novel leaching process followed by solvent extraction and electro-winning (SX/EW). This will not only be the first demonstration of the MBS leaching process at scale, but it will also be the first copper SX/EW plant to operate in Bulgaria.
"With more than thirty years experience in the hydrometallurgical recovery of copper using the environmentally clean SX/EW technology, we are a world leader in this area of plant design. Our expertise includes many in-house developments in SX contractor design, mixer design and plant arrangements, so we look forward to working with MBS on this SX/EW pilot plant design," said Malcolm Oliver, President of AK Engineering Services, part of Aker Kvaerner's European engineering and construction business.
The pilot plant is the pre-cursor to a full size pilot plant, which is scheduled to be built in 2004/5.
ENDS
For further information:
Vanessa Mourant, Aker Kvaerner, London, UK: Tel: +44 (0)20 7339 1064 or Email: vanessa.mourant@akerkvaerner.com
Sue Ledgerwood, Aker Kvaerner, Stockton-on-Tees, UK: +44 (0)1642 602221 or Email: susan.ledgerwood@akerkvaerner.com
NOTES TO EDITORS
1. Aker Kvaerner is a leading global provider of engineering and construction services, technology products and integrated solutions. Group activities span a number of industries, including Oil and gas upstream and downstream, Process, Pharmaceuticals, Metals, Power, Chemical Pulping, Environmental and Shipbuilding. Aker Kvaerner is a multi-local group of businesses with nearly USD 6 billion of annual revenues and around 34 000 employees in more than 30 countries.
AK Engineering Services
is one of the core businesses of Aker Kvaerner in Europe. It provides total asset life cycle solutions including conceptual design, engineering, procurement, project management, construction and commissioning, through to operation and maintenance services, modifications and process improvements. Also offered are consultancy services in reliability, business modelling and environmental, health, safety and risk management.
2. The SX/EW process
The aim of the Solvent Extraction (SX) plant is to produce a high grade, pure copper sulphate solution suitable for Electrowinning (EW).
Dilute, impure Pregnant Leach Solution (PLS) from the leach stage is contacted with an organic copper extractant, which has been diluted with a low volatility kerosene based carrier in a mixing tank. The immiscible aqueous and organic phases form an emulsion in the mixer, which allows for extremely efficient surface contact. Copper in the PLS is extracted into the organic phase during this contact by an ion exchange reaction.
The emulsion then flows into a settler where the two phases separate as they flow towards separate discharge launders. The aqueous phase, stripped of copper, is now called Raffinate and discharges to the Raffinate pond where it will be returned to the leaching operation as leach solution. The organic phase, now loaded with copper, discharges to the loaded organic storage tanks. From here it is pumped to the strip stage mixer/settler.
In the strip stage the loaded organic is contacted with spent electrolyte solution, which has been returned from the EW tankhouse. This solution contains 30-40g/L copper and 180g/L sulphuric acid. The spent electrolyte strips (removes) the copper from the organic phase into the aqueous phase during contact in the mixer. The strip reaction is the reverse of the extraction reaction.
The stripped organic is then separated from the electrolyte in the settler and discharged from the strip settler to the extraction stage mixer/settler where it is again contacted with PLS to extract more copper. The electrolyte is now called strong electrolyte and contains 40-50g/L copper and 160g/L acid.
The strong electrolyte is almost ready to be pumped into the EW tankhouse, but first it has to be thoroughly clean of any organic carryover (entrainment) and fine solid particles, both, of which, can lead to problems in the electrowinning circuit.
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