Optimization Gold Cyanidation Process to Increase Gold Extraction at Pongkor Gold Mining Business Unit Indonesia

Abstract

Pongkor Gold Mining has been operated for almost twenty years and produced more than 50 ton of gold. One of important process to in gold processing plant at PT Antam (Persero) Tbk. Pongkor Gold Mining Business Unit is CIL (Carbon In Leach) Process which cyanidation process occur. Pongkor has epithermal low sulfide and clay ore which have its own difficulty to process to get high gold extraction levels. There are many several variables in cyanidation process that can be optimized to increase gold extraction. Variables like free cyanide concentration, dissolved oxygen level, viscosity, and residence time had play role in on gold dissolution rate and gold extraction. Optimization has done gradually and not simultaneously in 2013, some improvements done in Pongkor are decreasing level of viscosity and increasing dissolve of oxygen in CIL circuit by choosing and adding effective materials to increase gold dissolution rate and stabilize residence time for maximizing gold leaching time. Decreasing level. of viscosity and increasing dissolve oxygen means higher dissolution rate will achieved and will give higher gold extraction levels and also impact on getting higher throughput. By that improvements, average gold extraction in 2013 is increase 2.5 - 4 % compare to average gold extraction in 2012. This successful project will be utilized over 300,000 dmt ore/year.