Precious and Base Metal Recovery or Electrowinning
With environmental concerns increasing, heavy metal-containing effluent from the mining and electroplating industries is under much more stringent government control. Electrowinning is a means by which the residuary metals from waste-water streams are recovered to be re-used or sold.
The metals that can be recovered by this method are copper (Cu), nickel (Ni), zinc (Zn) and cobalt (Co), and used in the recovery of cyanide-based electrolytes of gold (Au), silver (Ag), copper (Cu), zinc (Zn) and cadmium (Cd)- cyanide is electrochemically destroyed, due to the enhanced anode efficiency.
Different metals plate out at different voltages, so application of the different voltages will allow all metals to be recovered from a mixed metal effluent. Our Mixed Metal Oxide and Platinised Titanium Anodes have already gained acceptance in the Metal Electrowinning Industry and become the anodes of choice. This technology has all but replaced lead anodes offering a far cleaner alternative together with significant power and cost savings.
The CHEMELEC™ metal recovery system can also be used for the efficient recovery of metals from dilute solutions where conventional electrolysis (the driving of a non-spontaneous reaction with DC to discharge ions into electrolyte) cannot be considered.
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WHO?
- Mining Houses
- Metal Plating Industry
- National Government Mints
- Jewellers
WHY CHEMELEC™?
- Efficient Metal Recovery: typically 99%
- Minimal effluent treatment, with destruction of cyanide
- Minimal Labour & Maintenance Costs: simple process, minimal maintenance
- Compact with minimum requirements for installation
- Environmentally Beneficial: water recycled
- No Contamination of Process Solution
- Flexible Unit and Reservoir Sizing to suit specific application
THE PROCESS OUTLINED
- The Chemelec™ Cell, comprised of closely spaced Mixed Metal Oxide coated and expanded metal Platinised Titanium Anodes, is connected to the reservoir of dilute solution to be treated by a recirculating pump.
- The Cell itself is immersed in the solution through a patented, Fluidised Bed System, containing an appropriate quantity of inert/non-conducting ceramic/glass beads.
- As the electrical current is applied, metal is deposited upon the cathodes due to the dramatically enhanced plating efficiencies obtained by this patented system.
- When sufficient metal deposit is formed, the cathodes are removed and replaced by a stand-by set. Similarly. With enhanced anode efficiency, cyanide is electrochemically destroyed.
- In a plating application, the laden electrodes are directly re-used as anodes in the plating bath. In other applications, the recovered metal can be peeled off the electrode and the foil/sheets sold/re-sold.
NMT® also manufactures Mixed Metal Oxide Anodes for other metal recovery systems and fabricate these anodes to customers’ specifications.