Retreatability analysis of the Musina copper mine tailings in South Africa: an exploratory study

Abstract

In recent times, the potential beneficial uses of abandoned mine sites have been recognised and acted upon through the retreatment of tailings in order to win minerals of interest still available in economically viable concentrations. The most notable benefit (although not usually factored in financially) is that, once the tailings have been removed, the land has a greater potential to be developed further. The main aim of this study was to investigate the contents of copper and potentially harmful elements in the tailings of the Musina mine, an abandoned Cu mine in the northern Limpopo Province, in order to assess environmental hazards and to provide a first estimate of the feasibility of future economic rehabilitation. The concept of reclaiming was here seen in a broad way and ranged from the reworking of tailings or other residues to residential and/or recreational use. To quantify the potential economic importance and impacts of the metal content of the tailings, geochemical analysis of samples from auger holes and resource modelling were employed. Neutral to slightly basic pH values and very low concentrations of arsenic and lead showed that acid drainage and toxic groundwater contamination (apart from Cu itself) would not be a concern. Three-dimensional (3D) and two-dimensional (2D) models were applied to estimate the resource potential of the tailings dump. The models revealed that residual Cu in the Musina mine tailings is currently at 8555 tonnes. Accordingly, going forward, we recommend a formalised geometallurgical study to assess the economic feasibility of extracting Cu, with a view to reworking the copper tailings dump. It is very important that this tailings dump be mined in future, in order to extract all Cu and ensure that the sterilised land (up to 95 ha) can be used for other purposes.