Gold Recovery from High-Arsenic Containing Ores at Newmont's Roasters

The Newmont roasting plant in Carlin, Nevada, which began operation in December 1994, processes refractory ores and pyrite concentrates from various gold deposits. This study aims to analyze the impact of roasting temperature on gold recovery, particularly concerning high-arsenic ores. A thorough observation of gold recovery rates as a function of roaster temperature was initiated in October 2000, revealing that lower roasting temperatures around 500 °C yielded a more than 6 percent increase in recovery due to enhanced surface area of the calcine. The integration of an intelligent process control system proved crucial in maintaining optimal low roasting temperatures, resulting in gold recoveries ranging between 92 to 93 percent. However, subsequent roasting campaigns involving high-arsenic ores led to significant reductions in gold recovery rates, attributed to decreased porosity and surface area of the calcine due to increased arsenic content in the feed. This research emphasizes the delicate balance in processing high-arsenic ores and the critical role of roasting conditions in optimizing gold recovery outcomes.