Por: Johnston, Adam, director de Metalurgia y López, Leslie, Transmin Metallurgical Consultants.

Abstract

Mineral deposits are widely heterogeneous, and their mineralogical, physical, and chemical characteristics vary throughout the deposit. Consequently, the resource’s metallurgical performance, such as throughput, recovery, or product quality, also varies. Geometallurgy explains that performance variability uses geological knowledge, reduces risk, and identifies opportunities for improvement.  

Consequently, the samples used in metallurgical testwork need to address this variability. The use of samples with poor representativity in a geometallurgical program will lead to unrealistic predictions. Fatal flaws may be missed, or opportunities missed may result in excessive conservatism.

Deliberate human intent may also be at play, so a simple and transparent system for selecting and documenting samples is a valuable tool to demonstrate corporate compliance.

Describing sample representativity requires compliance with standards, such as NI 43-101 technical reports; however, many reports do not even give basic supporting information.

As a minimum, documentation should show what samples were used, their origin, the selection criteria used, and how they compare to the deposit in question. 

How does the unit or project management know if the samples used to support predictions were representative or not? 

This article provides a top-level resource review of some basic principles that can support a systematic and transparent sample selection process.