Metallurgical characterisation of George Fisher mesotextures and microtextures

Abstract

The design and operation of a mineral processing plant is dependent on the knowledge of the range of metallurgical characteristics of the ore throughout the mineral deposit. This thesis presents an alternative approach in the metallurgical characterisation of ore textures and their influence on metallurgical behaviour.Previous geological studies have introduced various scales of ore texture that include mesotextures (at the mesoscopic scale) that can be observed by an unaided and trained human eye and microtextures (at the microscopic scale). The metallurgical characterisation of mesotextures and their relationship with underlying microtextures provide the opportunity of using both scales of texture in an alternative and innovative ore characterisation procedure. However, a metallurgical relationship between mesotextures and microtextures must be established before this alternative ore characterisation procedure can be used.Samples of the mesotexture types found in the George Fisher silver-lead-zinc deposit were used to determine whether unique metallurgical characteristics existed for these mesotextures that included five mesotexture types ranging from massive to banded. The metallurgical characteristics assessed for the George Fisher mesotexture types included mineral head grade ranges, microtextural properties, grinding properties, level of naturally floating material, level of oxidation and reactivity, mineral recovery on a size-by-size basis, influence of fine regrinding on mineral separation, impact of head grade on mineral separation, the effect of mixtures of mesotextures on mineral separation and the ability to metallurgical model mesotextures and microtextures to estimate mineral recovery. The George Fisher mesotexture types and their underlying microtextures were shown to exhibit an extensive range of metallurgical characteristics that showed simple metallurgical characteristics from the massive mesotextures to more difficult characteristics from the banded mesotextures. The knowledge of these metallurgical characteristics of mesotextures and microtextures can be used as a predictive tool and improves metallurgical understanding with increased awareness over a wide range of metallurgical properties. The mesotexture classification system, that can be easily determined, removes the variability of the unknown metallurgical characteristics and provides the opportunity to optimise metal recovery.