Dundee Sustainable Technologies Inc. (DST) said it completed initial laboratory metallurgical testing in March, and the direct application of the CLEVR process on oxidised samples achieved gold extraction yields of 93.5% and 94.2% respectively for the distinct lots tested. 

In a previous announcement, DST had stated 95% or better as a target recovery rate for the process which uses sodium hypochlorite with a catalytic amount of sodium hypobromite in acidic conditions to put the gold into solution.

President and chief executive David Lemieux said: "Management of DST is very excited of the results obtained with our CLEVR process with the gold miner. Our team will continue working with the client to further develop this promising opportunity for DST." 

DST was mandated by the miner, based in the Asia-Pacific region, to conduct a metallurgical test program at its facilities in Thetford Mines, Canada.

The solid residues, produced as a result of the process, were tested successfully against the U.S. Environmental Protection Agency's toxicity criteria, confirming they can be considered as non-hazardous waste, DST added.

Contact time is short, and the process operates in a closed loop. All chemicals are recycled within the circuit and, sea water is also suitable where available.