MINING and Process Solutions (MPS) has been awarded an exclusive licence for the GlyLeach Process, a leaching technology developed by Curtin University in Western Australia for leaching of base and precious metals. The rights cover Australasia, North and South America, and Asia, with options to expand to other countries upon satisfying agreed criteria.

GlyLeach is an alkaline based process that will leach copper from copper oxide, mixed oxide and supergene sulphide ores, and even primary copper sulphide ores. It will also leach gold when the temperature of the Glycine is raised to 60 degrees.

Process inventor, Professor Jacques Eksteen from Curtin University’s Department of Mining Engineering and Metallurgical Engineering, said, “The process has a number of immediate applications including leaching of low grade ores, differentially leaching of copper and gold ores, upgrading concentrates, and tailings retreatment.”

The major reagent is Glycine, the simplest and cheapest of the amino acids, and is available in bulk ranging from food grade to technical grade. It has a number of attractive chemical and physical properties that gives it significant advantages over other copper or gold Lixivants:

• It is an environmentally safe and stable reagent. It is biodegradable and easily metabolized in most living organisms;
• It is active as a selective leach agent only when used in an alkaline based circuit between pH 8 and 12;
• It provides a step change in copper leaching with enhanced solubility of copper ions in aqueous solutions and forms stable complexes with copper. The work undertaken at Curtin University has shown it is a very effective leaching agent for almost all copper minerals apart from Chrysocolla, a copper silicate mineral;
• It is easily recovered and recycled. Apart from normal process losses (usually expected to be less than 5%), +99% of the Glycine is recoverable.

MPS technical director Frank Trask says it is a simple process that requires no new equipment to be designed, has low operating costs due to regeneration of principal reagents, and is expected to provide high copper recoveries with almost all copper minerals even Chalcopyrite; long considered the ‘Holy Grail’ of copper leaching. It will also offer the gold industry a non-toxic method of leaching gold, something that is becoming more important in many jurisdictions.

MPS managing director Ivor Bryan said the addition of the GlyLeach Process was an important addition to the portfolio of technologies it had assembled and could support. MPS also had exclusive agency rights in Australasia for Continuous Vat Leaching (CVL), a Canadian developed mechanical leaching process, and it was expected that the two technologies would be synergistic for a range of deposits.