RECYN III – THE NEW GENERATION OF GOLD PLANTS- REPLACING CARBON. By Malcolm Roy Paterson
PT GreenGold Technology, Indonesia Presenter and Corresponding Author Malcolm Roy Paterson malcolm@greengoldtechnology.com
ABSTRACT The Merrill-Crowe process, introduced at the turn of the 19th century, was for decades the standard method of recovering gold from cyanide solutions through the addition of zinc, and it is still in limited use today. In the 1970's Merrill-Crowe met competition from activated carbon, which overcame the need for solid-liquid separation and was suited to low-grade oxide ores. Carbon circuits are now the most widely used recovery method, with Merril-Crowe mainly restricted to high silver ores. Both carbon and Merrill-Crowe systems use cyanide as the gold lixiviant. The negative perception of cyanide as a toxic, environmental contaminant has encouraged researchers to look for an alternate lixiviant. However, there has been a limited success, and cyanide continues to be the mainstay of gold processing (1) . The public perception of cyanide as the bad boy of gold processing is not wholly justified, as the reputation mainly stems from its use in different historical applications and further degraded with several significant dam failures releasing toxic tailings. GreenGold Technology, (GGT), has taken the view that rather than continue an arduous and time-consuming search for an alternative lixiviant, the effort is better directed to enhancing what is a proven, cost-effective, and efficient product. GGT initially aimed the commercialisation of the ReCYN process at recycling cyanide from gold plant tailings to reduce the quantity of cyanide purchased (ReCYN I) and detoxifying CIL tailings before discharge to a storage facility (ReCYN II). Both these objectives result in a nett revenue instead of the high cost of destructive detox methods. Clean-up of plant tailings with the ReCYN process also involved the scavenging of residual solubilised gold escaping the carbon circuit. The question coming back from mining companies is "Can ReCYN fill all three objectives of recovering cyanide, detoxifying tailings, and being the primary circuit for recovering gold"? Hence ReCYN III, which combines active (Free) cyanide recycle, complexed cyanide metal recovery and gold/silver recovery in a single, simplified circuit. Two previous ALTA papers, (2017, 2019), have described ReCYN I and ReCYN II. The following article describes the ReCYN III process and its application to the Mt. Morgan Tailings Project in Queensland.
Keywords: Cyanide, gold, copper, resin, carbon, detoxify, recovery, economic and environmental.
ALTA 2020 Gold-PM Proceedings
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