Using Synergy Between Cyanide, Oxygen and Lead Nitrate to Improve Extraction and Reduce Opex / Capex in the Processing of Sulphide-Bearing Gold Ores

6 April, 2016 | White paper

GUY DESCHÊNES, P.Eng., MSc, PhD

Engineer, Precious metals mineral processing

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Abstract

In 2013, as the prices of precious metals dropped, investors moved their positions to equity markets for higher returns. As a result, the price of gold dropped further to below US$1,200 per ounce, prompting additional substantial outflows from gold investments. In response to lagging gold prices, major gold producers initiated large asset write-downs and cost-cutting programs. In 2015, this trend continued and gold mining stocks closed to lows not seen since the global financial crisis (GFC) of 2008. In the current economic climate, many projects have marginal economics, and the number of projects that have competitive development and production costs is declining. A competitive edge is particularly important with the decreasing grades of orebodies, increasing complexity of the mineralogy and increasingly demanding environmental constraints. In addition, higher cost producers seek to optimize their process to reduce operating costs. This paper presents some highlights of three case studies on optimization of gold leaching strategies that improved the economics of brownfield projects. Processing of sulphide-bearing ores was optimized by using the synergy between cyanide, lead nitrate and oxygen. The outcomes were a significant reduction in retention times while maintaining or increasing gold extraction and reducing cyanide addition and effluent treatment costs. A stirred tank reactor experimental program led to direct implementation of reliable leaching strategies from laboratory scale to production. This approach resulted in savings of $2.2 million to $15.2 million on the three brownfield projects discussed in this paper

Note that this white paper was the subject of a presentation at IMPC 2016: XXVIII International Mineral Processing Congress Proceedings.

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