[ TECHNOLOGY OPPORTUNITY 2005-016]

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A Novel Thiosulfate/Thiocyanate Gold & Silver Recovery Process
2005-016

Description:
A researcher at Queen’s University has developed a novel process for the recovery of gold or silver (as a solid) from thiosulfate and thiocyanate leachates. The process, which uses a low-cost, environmentally inert reagent, is suitable to pre-existing or green-field industrial leaching processes and results in the rapid and almost complete recovery of the precious metal.

By employing a reductive, co-precipitation process this novel method may provide a cost-effective alternative to existing recovery techniques such as carbon/resin adsorption and zinc/copper cementation. Bench testing has validated the effectiveness of this process as is demonstrated in the example below.

Effect of Ferrous Sulfate Consumption on Gold Recovery:

[Au] – 21.27ppm, 50ml
[(NH4)2S2O3] – 0.2 mol/L
[CuSO4] – 300 mg/L
[NH3] – 0.9 mol/L
[FeSO4] – 50 g/L
FeSO4 – 1.6 ~ 6.4 kg/m3
Agitation – 5sec @ 210 rpm

Advantages:
Additional advantages of the process include (1) minimum copper loss; (2) absence of any thiosulfate loss in the recovery process; (3) no introduction of harmful ions into the leachate; and (4) the barren solution can be easily recycled.

Status of Commercialization:
The technology is protected by international patent application PCT/CA2007/000566, "Precious Metal Recovery from Solution." PARTEQ Innovations, the technology transfer office of Queen’s University, is seeking industrial partners interested in licensing the intellectual property.

Contact:
Jason Hendry
Manager, Commercial Development
Phone: 613. 533. 2342
Fax: 613. 533. 6853
Email: jhendry@parteqinnovations.com

Ref tech ID 2005-016