Principles and Economic Considerations of Electrochemical Treatment of Cyanide-Laden Wastewater

Abstract

The mining industry is a global economic driver that produces the metals and minerals required to sustain our expanding technological advancements. The gold mining industry in particular is integral to the production of electronics, copper, and the solar panels that are required for the long-term growth of the renewable energy sector. Significant demand in recent years has lead the gold mining industry to consume 20% of the annual production of cyanide, which is used as a leaching reagent. The health and environmental risk posed by the wide spread use of cyanide has raised public concern, and as a result ever more stringent wastewater discharge requirements are being implemented. The current conventional method of treating cyanide requires a large amount of real estate, leads to persistent toxicity, and prevents mine operators from successfully meeting land reclamation requirements. Electrochemical oxidation and coagulation of cyanide offers an alternative wastewater treatment method that requires less real estate, is amenable to automation, and capable of meeting new stringent requirements. This paper presents the technical and economic framework required to assess the economic validity of employing electrochemical treatment methods of cyanide-laden wastewater. This framework is applied at the mine of an industrial partner located in Brazil who is currently using traditional chemical coagulation to treat 25 m $^3$ /h of cyanide-laden wastewater. The framework is further used to create a stochastic model of the expected treatment cost typical in the mining industry by varying inputs into the model.