Commercial heap biooxidation of refractory gold ores - revisiting Newmont's successful deployment at Carlin

摘要

Newmont Mining Corporation pioneered the investigation, development, and commercial-scale implementation of refractory gold whole-ore heap biooxidation, during a period spanning 1988-2010 at Carlin, Nevada (Figure 1 summarizes key developments and gold price during this period). Basic and applied research and development from 1988-1999 included laboratory test work and increasingly larger pilot test heaps leading to full-scale implementation of a process that was estimated to contribute 120,000-180,000 oz/year (12.2 t total by May 2005; 1) to Carlin's gold production from 2000-2005. Even within Newmont, it is difficult to determine exactly when the closure of the commercial operation (internally referred to as the Refractory Leach Project) occurred, but by combining annual U.S. Securities and Exchange Commission annual 10-K reports and internal reports, it can be concluded that initial planning for project closure began in 2007, operating data exist for 2008 and 2009, and a 2011 final closure plan the biosolution pond described cessation of operations in 2010. It is likely then that the commercial biooxidation plant contributed at least another 5 tonnes (ca. 160,000 oz) of gold to Carlin production before closure in 2010, after a decade of operation.