Identifying the mineralogy in geological samples is a primary objective and foundational component across the geoscientific disciplines of the exploration-mining-geometallurgy-remediation chain.
Spectral Geoscience use infrared spectroscopy as a tool to extract qualitative and quantitative mineral information from geological samples to support the objectives of exploration geologists, mine geologists, geotechnical engineers, geometallurgists and environmental engineers.
Examples of applied hyperspectral-mineral results include:
exploration surface samples
Identify the mineralogy of field samples collected in early reconnaisance field mapping and trench sampling. Combine with GPS coordinates to produce geographically registered mineral map products; integrates readily with complementary exploration datasets and provides input to exploration and mineral system models. Make timely decisions, reduce risk, expedite the generation, evaluation and prioritisation of new targets and drill hole planning.
Exploration drill core and chips
Identify key alteration minerals; delineate their vertical and lateral spatial distribution, zonation patterns and overprinting relationships. Characterise the 3D physico-chemistry properties and architecture of a deposit based on the identification of minerals diagnostic of particular temperature and pH formation conditions. Investigate mineral spectral signatures that may distinguish barren from mineralised intrusions and determine distal to proximal vectors to mineralisation.
mineral prospectivity modelling
Hyperspectral mineral results provide digital input as alpha or numeric variables to develop a prospectivity model based on the combination of favourable mineralogical associations with ore in a deposit. Interpolate between samples or drill holes, integrate with ancillary data, perform GIS interogation to highlight potential extensions to ore or prospective sites in geologically similar terranes.
Mineral spectroscopy is a fast and cost effective analytical technique for the detection of swelling clays (e.g. montmorillonite) to aid geotechnical risk assessment and improve stability in mine design.
Use spectral data collected from field samples to validate airborne and spaceborne mineral maps. Conversely, use mineral results from handheld spectrometer field mapping to plan for and expediate a regional exploration program using airborne or satellite sensors.
Logging the mineralogy in blast hole chips improves objectivity and consistency in bench mapping. Interpolation between holes establishes whether continuity of alteration related to mineralisation/grade is present.
Hyperspectral drill core logging of alteration mineralogy related to mineralisation provides soft boundaries on the distribution of grade in resource modelling and an additional layer of evidence and confidence to support resource estimation. Hyperspectral logging can highlight continuity and the degree of connectivity between drill holes as well indicate potential extensions of mineralisation into areas yet to be drilled.
MINE PLANNING & DEVELOPMENT
Hyperspectral core logging enables the mineral inventory of an ore deposit to be rapidly and consistently characterised into domains to assist with mine planning and development. Operational benefits come with improved understanding of the mineralogical characteristics of the orebody and surrounding gangue mineralogy that typically constitutes the bulk tonnage of a deposit.
Mineral spectroscopy is often best suited to logging the dominating gangue minerals associated with sulphide deposits as most sulphides do not generate an unambiguous infrared spectrum.
Hyperspectral core logging compliments grade, lithology and structural information in mine planning and development. Improvements in mine-mill accounting and reconciliation can be achieved by incorporating hyperspectral mineralogical core logging data into the mine model to reduce uncertainty.
Applied examples include; stock pile designation, sorting and blending based on separating ore from gangue mineralogy; similarly over a conveyor belt sorting feed to appropriate crusher or mill. Provides strong links and input into subsequent geometallurgical flow sheet design.
Hyperspectral core logging provides continuous down hole, macro-scale mineral results for input to geometallurgical block models and flowsheet design. Overcomes the industry recognised problem of insufficient sampling to adequately represent the variability across a typical ore body. Guides the selection of core samples for essential metallurgical testwork (e.g. JKDWT, BWI). Complimentary to spatially discrete micro-scale point measurements (e.g. QEMSCAN).
Identification of deleterious minerals in metallurgical processes resulting in lower recovery (e.g. talc in froth flotation consumes large amounts of reagents; clay coatings reducing grinding efficiency).
Identifies the nature and deportment of mineralogical impurities that dilute grade, for example, kaolinite, gibbsite and quartz in iron ore bodies that also incur smelter penalties.
Delineates mineralogical spatial domains whose relationships with ore may indicate differing metallurgical processing requirements for optimal recoveries. Identifying these domains in advance can reduce energy consumption and improve an operations efficiency and ore recovery economics.
Mineralogy can be used as a proxy to predict mine-scale physical processing performance. For example, comminution varies according to rock hardness that is largely controlled by the constituent mineralogy (and texture). Also, acid consumption is governed by the presence and abundance of acid consuming minerals such as carbonates.
Mineralogically characterise heap leach pads, stream sediment samples, road spillage from trucks etc to prevent/mitigate/assess/monitor environmental impact and plan for environmental compliance.
constrain Geophysical interpretation
Knowledge of the subsurface mineralogy enables geophysical interpretation to be constrained and improves the accuracy of reported results.