Development of a Predictive Geometallurgical Recovery Model for the La Colosa, Porphyry Gold Deposit, Colombia

摘要

La Colosa, Colombia is a large gold-porphyry deposit currently undergoing feasibility studiesrnby AngloGold Ashanti. This period of development allows the opportunity to apply innovativernand emerging testing and modelling methods to provide a predictive geometallurgical recoveryrnmodel for the deposit. By partnering with the AMIRA P843A Geometallurgical Mapping and MinernModelling (GeMIII) research project, the geological and mineralogical data are analysed with respectrnto liberation and recovery methods. This will allow the variability in the geology and mineralogyrnof the deposit and key relationships recognised in the data to be included in the development ofrna model to help predict recoveries of the gold. Many aspects of the gold mineralisation such asrngold paragenesis, associations, grain size and texture are determined and analysed using opticalrnmicroscopy, Mineral Liberation Analysis (MLA), and laser ablation (LA-ICP-MS). At La Colosa therngold has been located in sulfi des (eg pyrite, pyrrhotite, and chalcopyrite), silicates, along silicaternphase boundaries, and among the pyrite-rich intermediate argillic alteration. Further testing andrnanalysis will also determine if ‘invisible’ gold is present in the pyrite, pyrrhotite, and chalcopyrite.rnRecovery methods can also be determined and tested after combining the results of mineralogyrntests with other data (eg results of comminution tests). Indices for the mineralisation and recoveryrnare developed using image analysis and analytical testing. These indices are correlated withrnrecovery data from the company to develop a predictive block model for recovery. The goal is torndevelop cost-effective, effi cient methods to analyse the mineralogy and geology of the deposit;rnunderstand the variability in the mineralogy, geology, and recovery; and construct a predictiverngeometallurgical recovery model.