The process mineralogy of mine wastes

The discipline of process mineralogy developed through the recognition that metallurgical flowsheets could be optimised by thorough characterisation of the precursor ore mineralogy, mineral associations, grain size and textures. In a procedure analogous to process mineralogy it is shown here that effective characterisation of mine wastes for Acid Rock Drainage and Metal(loid) Leaching (ARDML) potential must follow a similar set of robust practices which include: (i) representative sampling; (ii) static/screening level geochemical tests and qualitative mineralogical assessment; (iii) longer-term kinetic geochemical tests and quantitative mineralogical assessment; and (iv) quantitative numerical modelling to assess source term chemistry associated with the mine facilities and thereby determine potential impacts to receptors. This process is dependent on a sufficiently robust drill core database and a detailed mine plan through which an assessment of mine wastes is possible. Such detailed characterisation may be limited by insufficient budgets, however omission of a thorough mineralogical investigation may lead to a lack of understanding of the primary geochemical controls on mine waste behaviour. In turn, this can lead to over- or under-engineering of mine facilities, which can have financial and/or environmental implications. Several case studies are presented to illustrate how mineralogy can be applied to solve problems in ARDML prediction and mitigation, specifically within waste rock assessment.