title: Fate of the naturally occurring radioactive materials during treatment of acid mine drainage with coal fly ash and aluminium hydroxide.
abstract: Mining of coal is very extensive and coal is mainly used to produce electricity. Coal power stations generate huge amounts of coal fly ash of which a small amount is used in the construction industry. Mining exposes pyrite containing rocks to H2O and O2. This results in the oxidation of FeS2 to form H2SO4. The acidic water, often termed acid mine drainage (AMD), causes dissolution of potentially toxic elements such as, Fe, Al, Mn and naturally occurring radioactive materials such as U and Th from the associated bedrock. This results in an outflow of AMD with high concentrations of sulphate ions, Fe, Al, Mn and naturally occurring radioactive materials. Treatment of AMD with coal fly ash has shown that good quality water can be produced which is suitable for irrigation purposes. Most of the potentially toxic elements (Fe, Al, Mn, etc) and substantial amounts of sulphate ions are removed during treatment with coal fly ash. This research endeavours to establish the fate of the radioactive materials in mine water with coal fly ash containing radioactive materials. It was established that coal fly ash treatment method was capable of removing radioactive materials from mine water to within the target water quality range for drinking water standards. The alpha and beta radioactivity of the mine water was reduced by 88% and 75% respectively. The reduced radioactivity in the mine water was due to greater than 90% removal of U and Th radioactive materials from the mine water after treatment with coal fly ash as ThO2 and UO2. No radioisotopes were found to leach from the coal fly ash into the mine water.
authors.affiliation: Environmental and Nano Science Group, Chemistry Department, University of the Western Cape, Modderdam Road, Private Bag X17, Bellville, 7535, Cape Town, South Africa. Electronic address: gmadzivire@gmail.com.
authors.forename: Godfrey
authors.initials: G
authors.lastname: Madzivire
authors.affiliation: Department of Nuclear Physics, iThemba LABS, P O Box 722, Somerset West, 7129, South Africa.
authors.forename: Peane P
authors.initials: PP
authors.lastname: Maleka
authors.affiliation: Environmental Geosciences, Council for Geoscience, Silverton, Pretoria, South Africa.
authors.forename: Viswanath R K
authors.initials: VR
authors.lastname: Vadapalli
authors.affiliation: Department of Ecology and Resources Management, School of Environmental Studies, University of Venda, Private Bag X5050, Thohoyandou, 0950, South Africa.
authors.forename: Wilson M
authors.initials: WM
authors.lastname: Gitari
authors.affiliation: Physics Department, University of the Western Cape, Modderdam Road, Private Bag X17, Bellville, 7535, Cape Town, South Africa.
authors.forename: Robert
authors.initials: R
authors.lastname: Lindsay
authors.affiliation: Environmental and Nano Science Group, Chemistry Department, University of the Western Cape, Modderdam Road, Private Bag X17, Bellville, 7535, Cape Town, South Africa.
authors.forename: Leslie F
authors.initials: LF
authors.lastname: Petrik
mesh_terms: D000143:Acids / Q000737:chemistry*; D000536:Aluminum Hydroxide / Q000737:chemistry*; D001417:Background Radiation; D060729:Coal Ash / Q000737:chemistry*; D008906:Mining; D014875:Water Pollutants, Radioactive / Q000302:isolation & purification*
chemical_list: D000143:Acids; D060729:Coal Ash; D014875:Water Pollutants, Radioactive; D000536:Aluminum Hydroxide
keywords: Acid mine drainage; Fly ash; Naturally occurring radioactive materials; Potentially toxic elements; Pyrite; Target water quality range