Mineralogical study of gold ores at the Casa Berardi Mine, Quebec

在魁北克的Hecla矿业公司的Casa Berardi矿，黄金的回收率是可变的，但可变性的原因还没有完全了解。Hecla地质学家已经确定的两个关键参数是Preg robbing（金优先吸附在碳质材料上）和矿石的砷浓度。最终，这两个问题的解决方案需要更好地了解矿石矿物学和矿井中的碳质材料。碳质材料的研究将包括拉曼光谱分析，并将使用岩相学、扫描电子显微镜（SEM）、电子微探针（EMP）和二次离子质谱（SIMS）分析的组合来研究金和砷全岩浓度之间的关系。岩相学将确定分布（例如，作为毒砂中的包裹体或作为"游离金"等）扫描电镜分析将确认金矿物学，并提供毒砂成分的初步估计;电磁脉冲 分析将确定毒砂的主要和微量元素组成，SIMS分析将确定毒砂中的金浓度。所有这些分析将对代表不同矿化带的样品进行。矿石和含碳物质的分析将根据与较低回收率相关的特征进行解释。这项研究对公司的潜在好处是，通过了解哪些矿物学因素影响金回收率，可以使选矿更有效。提高金矿开采效率可以产生重大的经济影响，使整个加拿大社会受益。

At Hecla Mining Company's Casa Berardi Mine, Quebec, the recovery rates of gold are variable, but the causes of the variability are not fully understood. Two key parameters that have been identified by Hecla geologists are Preg robbing (the preferentially absorption of gold on carbonaceous material) and the arsenic concentrations of the ore. Ultimately, the solutions to both of these problems require a better understanding of the ore mineralogy and the carbonaceous material at the mine. The investigation of the carbonaceous material will consist of analyses by Raman spectroscopy and the relationships between gold and arsenic whole rock concentrations will be investigated using a combination of petrography, scanning electron microscopy (SEM), electron microprobe (EMP) and secondary ion mass spectrometry (SIMS) analyses. Petrography will establish the distribution (e.g., as inclusions within arsenopyrite or as 'free gold' etc.) and sizes of gold particles; SEM analyses will confirm the gold mineralogy and provide a first estimate of arsenopyrite compositions; EMP analyses will establish the major and trace element compositions of arsenopyrite and SIMS analyses will determine the gold concentrations in arsenopyrite. All of these analyses will be carried out on samples that are representative of different zones of mineralization. The analyses of the ore and carbonaceous material will then be interpreted in terms of which characteristics are associated with lower recovery rates. The potential benefit of this study to the company is that, by knowing which mineralogical factors influence gold recovery, mineral processing can be made to be more efficient. Improving the efficiency of gold mining can have a significant economic impact, which benefits Canadian society as a whole.