Characterisation of non-sulphide zinc deposits using QEMSCAN®

Non-sulphide zinc deposits are important potential resources of zinc and other metals, which require accurate characterisation of the mineralogy, texture and grade for successful processing. The mineralogy of these deposits has traditionally been examined using optical microscopy, cathodoluminescence, XRD, SEM and EPMA. This study develops QEMSCAN® technology to rapidly acquire spatially resolved mineralogical data from non-sulphide zinc ores from Accha (Peru) and Skorpion (Namibia). The resulting modal and textural data provides significant additional information on the distribution of the ore minerals including detail on the trace minerals, grain size distributions, and mineral associations. The data were verified by XRD to assess clays and compositionally similar mineral polymorphs and EPMA to accurately establish mineral compositions. The detailed mineralogical knowledge from this study improves the lithotyping of the deposits and will benefit the ore processing strategies for these complex deposit types. The particular processing implications include assessments of the acid consumption, the abundance and distribution of penalty elements, and potentially low zinc recoveries relating to iron oxyhydroxides and sauconite.

Research highlights
► The mineralogy of non-sulphide zinc deposits can be quantified by QEMSCAN®.
► QEMSCAN® identified trace phases and quantified the Zn content of Fe and Mn phases.
► QEMSCAN®, XRD and EPMA are invaluable to evaluate this ore type.
► Improved lithotyping may allow enhanced processing and recovery of Zn for Accha.