Challenges in Ore Characterization
The overall grade of many common ore types is gradually declining. For example, copper ore bodies at Cu-grades >5% with bornite as the primary copper mineral species are no longer the rule but the exception. Much more common are copper ores of 1% copper grade, with a multitude of copper sulphides contributing to copper grade, such as chalcocite, chalcopyrite and covalite. As a result, plant operators are increasingly challenged to understand which minerals actually contribute to grade, as each mineral is likely to behave differently to comminution, flotation or leaching.
Elemental deportment also entails the comprehensive understanding of minerals that do not contribute to grade, as well as penalty elements that can cause environmental concerns with tailings storage (e.g. Arsenicum), affect the efficiency of processing (e.g. hydrophobic gangue minerals such as talc), or affect the value of the final concentrate (e.g. bismuth in a copper sulphide concentrate, or chrome in a PGM concentrate).
Traditional bulk geochemical analysis techniques such as AA, ICP or XRF do not offer a capability to measure elemental deportment -- XRD and automated mineralogy do. In addition, automated mineralogy also provides the textural context of elemental and mineral deportment.