MSc(Eng) Project title Characterising the acid mine drainage potential of fine coal wastes
(Supervisors: Dr JL Broadhurst, Dr M Becker, Prof J-P Franzidis) Graduated: 2013
Acid mine drainage (AMD) is one of the major environmental challenges facing the South African mining sector. South Africa’s long mining history has led to a growing concern regarding coal-related AMD particularly since coal wastes have generally been poorly characterised. The management of AMD is strongly associated with the reliability of tools and mechanism used in the prediction of the acid generating characteristics in coal wastes. To date, most of the methods for the prediction of AMD have been largely developed for sulphidic wastes from the processing of hard-rock ores, which have very different characteristics to coal wastes. This study entailed the application and comparison of a matrix of tools including, QEMSCAN, acid base accounting and biokinetic shake flask tests, for characterising the AMD generating behaviour of coal waste.
The use of a combined suit of characterisation tools demonstrated the advantages in providing robust and reliable data sets in predicting coal related AMD. The biokinetic tests expanded on the static tests findings’ by demonstrating the acid producing potential under conditions of microbial activity under both acidic and circum-neutral pH conditions. The shake flask tests demonstrated that although a measured acid neutralising capacity may provide short term alleviation, fluid flow and the movement of effluent in a natural system will likely lead to the loss or depletion of this neutralising capacity. The adaptability of the biokinetic tests to semi-batch conditions provides useful information on the relative rates of acid generating and acid consuming reactions not only under microbial oxidation conditions but also in a pseudo open system. The study also demonstrated a higher AMD producing trend toward the smaller size fractions, which was attributed to a higher concentration of acid producing pyrite in these fractions. Further development and optimisation of several of the AMD characterisation techniques has been recommended in order to improve their consistency and reliability.
Kotelo L. 2013. Characterising the Acid Mine Drainage Potential of Fine Coal Wastes, MSc dissertation, University of Cape Town
Oral conference presentations
Kotelo L., Broadhurst J.L., Becker M., Harrison S.T.L., and Franzidis J-P. 2011. Sulphur deportment and related impacts during coal preparation in South Africa: A focus on acid Rock drainage. SAIMM Mineral Processing Conference, Cape Town, 4-5 August 2011
Kotelo L., Broadhurst J.L, Becker M., Harrison S.T.L. and Franzidis J-P. 2010. Sulphur deportment and related impacts in the coal sector: A focus on acid rock drainage. A focus on acid rock drainage. FFF 15th Southern African Conference on Clean Coal to Clean Energy Research & Development to meet Supply and Demand for Africa, Johannesburg, 17 & 18 November 2010.