Abstract: The acidification of mine waters is generally caused by metal sulfide oxidation, related to mining activities. These waters are characterized by low pH and high acidity due to strong buffering systems. The standard acidity parameter, the BNC (Base Neutralization Capacity), is determined by endpoint titration, and reflects a cumulative parameter of both hydrogen ions and all buffering systems, but does not give information on the individual buffer systems. It is demonstrated that a detailed interpretation of titration curves can provide information about the strength of the buffering systems. The buffering systems are of importance for environmental studies and treatment of acidic mining waters. Titrations were carried out by means of an automatic titrator using acidic mining waters from Germany and Canada. The curves were interpreted, compared with each other, to endpoint titration results and to elemental concentrations contained therein. The titration curves were highly reproducible, and contained information about the strength of the buffer systems present. Interpretations are given, and the classification and comparison of acidic mining waters, by the nature and strength of their buffering systems derived from titration curves are discussed. The BNC-values calculated from the curves were more precise than the ones determined by the standard endpoint titration method. Due to the complex buffer mechanisms in acidic mining waters, the calculation of major metal concentrations from the shape of the titration curve resulted in estimates, which should not be confused with precise elemental analysis results. Conclusion. Titration curves provide an inexpensive, valuable and versatile tool, by which to obtain sophisticated information of the acidity in acidic water. The information about the strength of the present buffer systems can help to understand and document the complex nature of acidic mining water buffer systems. Finally, the interpretation of titration curves could help to improve treatment measurements and the ecological understanding of these acidic waters.

Abstract: ERWAT's Ancor Wastewater Treatment Works on the Far East Rand commissioned a 10 Ml/day full-scale plant to treat toxic mine-water from the Grootvlei gold mine using primary sewage sludge. The R15-million plant is treating sulphate rich acid mine drainage using the Rhodes BioSURE Process. First, the pumped mine-water is treated at a high-density separation (HDS) plant to remove iron and condition pH levels. Then it is pumped two km via a newly-constructed 10 Ml capacity pipeline to the Ancor works. This mine-water is then mixed together with primary sewage sludge in a mixing tank from where a splitter box directs the material to eight biological sulphate reducing reactors or bioreactors. The overflow water which is rich in sulphide is pumped through the main pump station to another mixing box. Here, iron slurry is mixed with the material before it is again divided between four reactor clarifiers for sulphide removal. The overflow water, now containing reduced sulphate levels and virtually no sulphide is pumped to Ancor's biofilters for removal of remaining Chemical Oxygen Demand (COD) and ammonia following the conventional sewage treatment process for eventual release into the Blesbokspruit.

Abstract: Mining at the Mt Leyshon Gold Mine in semi-arid north Queensland stopped in 2002. Newmont Australia has recently initiated a thorough post-closure water management study of the site by revisiting the existing information and conducting new water-related investigations. The focus of this paper. which is the first publication on post-closure environmental management of the site. is an overview of the site water quality in view of the sources and spatial distribution of polluted mine water, and also the performance of cover systems in controlling water flux though mine wastes.