Meeting the challenge of penjom gold mine’s geology in the recovery of fine gold in carbonaceous ores

Abstract

Ore bodies that were previously deemed unfeasible to mine have now become economically feasible due to the increase of gold price in recent years. In addition to the increase in gold price, some processes that have been under development have now been proven viable. Also, the geology of a mine would influence the recovery strategy of the gold from the ores. Evidence of this is seen at Penjom Gold Mine (PGM) in Malaysia, where carbonaceous gold ores are mined and processed. PGM produces one of the world’s worst preg-robbing gold ores, yielding very low recoveries from traditional carbon-in-leach methods. Preg-robbing is preferential absorption of gold-cyanide complex ions [Au(CN) 2-] by organic carbon in the carbonaceous gold ores. The gold processing facilities in PGM are designed to address the challenges of fine gold recovery from carbonaceous and sulphide ores. Since employing the resin-in-leach process in mid-1999, gold recovery rates consistently run close to 90% which is a remarkable 30% improvement over recovery rates using activated carbon. The resin-in-leach process is not as common and appears as a result of thorough development work conducted since late 1940s. The objective of this paper is to analyse how preg-robbing carbonaceous gold ores can be processed economically. This objective will be achieved through literature research and using the most recent practical work findings from PGM. Optimization of process parameters in order to achieve acceptable gold recovery under low operating costs will be emphasized. The most important finding from this paper is the success of the resin-in-leach process in recovering gold from carbonaceous gold ores and the most up-to-date process parameters of cyanide concentration, temperature, and pH used in the hydrometallurgical circuit.