Geometallurgical Sampling and Testwork for Gold Mineralisation: General Considerations and a Case Study

Abstract

Geometallurgy seeks to derisk the extraction of primary resources by developing optimal strategies across resource/reserve evaluation, mine planning, mineral processing, environmental management (including waste management), and energy use. Predictive geometallurgy is the crux of modern geometallurgical practice, which leads to a data-rich 3D block model(s). The geometallurgical approach aims to quantify variability through different sample types, including in situ and direct measurements; physical samples; process samples within the plant; and in-line sensor-based measurements. Sampling considerations across sample type, representativity, number of samples required, sample integrity, Quality Assurance/Quality Control, and reporting results in the context of international codes are emphasised. A geometallurgical protocol was developed to obtain multivariate data for highly heterogeneous gold-bearing conglomerate mineralisation. The protocol emphasises the importance of collecting high-quality samples through the use of diamond drill core and early implementation. The programme aimed to acquire an accurate head grade of each core intersection prior to destruction by metallurgical testwork. Core scanning and comminution test work was undertaken prior to the head assay. The protocol was developed so as to allow each core interval to be submitted for comminution testwork, recombined for head grade determination by PhotonAssay™, and subsequently submitted for gold recovery testwork. All core was scanned prior to testwork and assay, which collected digital imagery, geochemistry, and bulk density data. A comprehensive quality assurance and quality control system was implemented for the programme. This paper presents an overview of geometallurgical sampling and the development and implementation of the Beatons Creek testwork programme in support of a Pre-Feasibility Study.