“Geometallurgy is the study of the drivers of metallurgical response that lie in the geology and mineralogy of the rock that is exploited.” (Steve Williams, Jan 2010)
Mineral deposits are heterogeneous bodies – variability in their response to metallurgical process is a real and an important reality of all mineral deposits. However, the recognition of this reality for project feasibility studies, has not been applied well historically. The consequence of this is that some operations have struggled with metallurgical performance because they didn’t anticipate difficult zones in their mineral deposit. Clearly, an understanding of the variable metallurgical response ore will deliver (when treated through a fixed “black box’ processor), before the real operation, will lead to better planning and economic optimisation of a new mining project.
The physical and chemical aspects associated with the mineralogy and textures of the ore are the fundamental drivers of the metallurgical performance of that ore. There is infinite variability involved in the possible range of mineralogy and texture, in any given deposit. However, to understand, for project planning and ultimately project feasibility studies, the variability that exists in a deposit, we simplify this task by utilising geological sub domains. These geological sub domains are sub domains of the overall geological entity, characterised by its geological model type (eg porphyry Cu type etc). These sub-domains permit us to take a complex range of mineralogy and texture and simplify, for characterisation of metallurgical response. Characterisation, analysis and test work associated with samples that represent the various sub-domains that exist in a deposit will then permit us to effectively map the range of metallurgical performance that exists within our deposit.
Put another way and simply – if we have rock that is the same rock type and mineralogy, in Chile or Uzbekistan (or anywhere else) and if we apply the same metallurgical process (the “black box”) – we will get the same metallurgical response as output.
Geological models of mineral resources were developed to assist exploration by trying to understand the deposits’ genesis and “form”. As such, they were not developed to characterise the mineralogical and textural variability that exists within a deposit. Nevertheless, these geological models provide a succinct framework to tackle this complex variability issue.
Metallurgical performance can be influenced by a large number of variables that relate to the rock mineralogy and texture. As an indication, this includes parameters such as liberation size, gangue sulphide type and amount, non-sulphide gangue mineral type and content etc. These components are mentioned here to indicate that metallurgical performance classification revolves around mineral parameters, but using different classification types and different terminology, than those used in geological model descriptions.
An important part of the evolution of geometallurgy as a science, for earth science professionals, is the coming together of geologist and metallurgists and particularly a common understanding between them, including the way rocks are described.
GMT GeoMet Tech will describe the sub domains that will characterise a deposit as metallurgical or mineralogical domains. These sub domains will point to geologically recognised sub domains but will be described in those criteria that are ultimately important to metallurgical performance. It is possible that a particular metallurgical domain may be associated with more than one type of geological domain. This occurs because what may be an important geological classification (for model description), is not a significant parameter for metallurgical performance.