Title: Inorganic contaminants attenuation in acid mine drainage by fly ash and its derivatives: column experiments

Authors: Wilson M. Gitari; L.F. Petrik; David L. Key; Charles Okujeni

Addresses: Department of Ecology and Resources Management, University of Venda, Private Bag X5050, Thohoyandou, 0950, South Africa ' Environmental and Nano Sciences Group, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, 7535, South Africa ' Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, 7535, South Africa ' Department of Earth Sciences, University of the Western Cape, Private Bag X17, Bellville, 7535, South Africa

Abstract: Treatment of AMD with fly ash (FA) is a promising technology but solid residues (SR) generated in the process pose a disposal challenge. This study evaluates the suitability of the SR and SR, FA/ordinary Portland cement (OPC) blends for backfill in mine voids and in-situ treatment of AMD flows. The mitigation of AMD in a mine void was simulated by addition of simulated acid mine drainage (SAMD) to FA, SR, SR + 25 % FA and SR + 6 % OPC packed columns. Acidity neutralisation in AMD was achieved over the study period. PHREEQC modelling indicated that precipitation of contaminants bearing mineral phases contributed to low levels of contaminants. Leaching of toxic trace elements and attenuation of contaminants strongly depended on the pH regime. Results revealed that backfill of coal mine voids with SR is a promising approach for large scale disposal of SR and treatment of AMD flows insitu.

Keywords: fly ash; acid mine drainage; AMD flows; in-situ treatment; backfilling; acidity; inorganic contaminants; waste management; waste disposal; solid residues; Portland cement; mine voids; simulation; environmental pollution; modelling.

DOI: 10.1504/IJEP.2013.053177

International Journal of Environment and Pollution, 2013 Vol.51 No.1/2, pp.32 - 56

Accepted: 27 Jan 2011
Published online: 28 Feb 2014 *

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