Canada-based NanoStruck Technologies has recovered as much as 96% of 9.1g per tonne, or 0.32oz per tonne, of gold from tailings samples, as part its tests during the last three months.
The company used nanotechnology technique and industrial collaboration for specific milling, pryometallurgy and hydrometallurgy processes, combined with proprietary organic compounds.
The testing involved careful roasting of tailings in laboratories.
On application of the Nanostruck techniques to tailings that were earlier roasted at the source site, the recovery rate was 88%. Multi-fold higher than earlier attempts by other firms using alternative technologies like cyanide leaching.
From the same already roasted sample, conventional carbon in leach processes had resulted in less than 10% recovery of gold.
The volume of tailings at the source site is estimated to be between 450,000t and 500,000t. NanoStruck is in talks with the owners of the source site regarding potential contracts for processing the mine tailings at the source site.
A Swiss testing services firm carried out the head assays and sampling, while an optical microscopic study was performed by Petrolab, to verify the representativeness of the tailing samples as well as the percentage of precious metal contained in them.
NanoStruck interim CEO and board chairman Bundeep Singh Rangar said: "We are very excited to announce these tremendously high recovery rates, involving non-cyanide hydrometallurgy and nanotechnology based processes, which could be transformative for the mining industry."
Bg Partners senior mining consultant Brian Mok said: "High-value refractory ore and tailings would be very well-suited for this process as well as jurisdictions where the use of toxic materials such as cyanide is undesirable or unacceptable."
Image: Recovery rates of gold from mine tailings are much higher than expected by industry observers. Photo: courtesy of Ponsulak.