Development of a Co-Disposal Protocol for the Neutralization and Amelioration of Acid Mine Drainage with Fly Ash

摘要

The primarily coal based production of electricity in South Africa results in approximatelyrn20 Mt of highly alkaline, aluminosilicate fly ash (FA) being produced per annum.rnAcid mine drainage (AMD) associated with coal mining is produced by pyrite oxidationrnresulting in highly acidic waters with elevated sulfate, certain heavy metals and totalrndissolved solids (TDS) levels. AMD leaching into groundwater has a deleterious impactrnon the environment.rnIn this study, the potential of co-disposing AMD with fly ash was investigated atrnlaboratory and pilot plant scale. The primary goals were development of a co-disposalrnprotocol aimed at neutralization of AMD and reduction of heavy metal content. Thernco-disposal process was initially tested at laboratory scale based on the followingrnparameters: ash neutralization potential, final desired pH and the heavy metal removal.rnBatch processes were conducted at laboratory and pilot scale by direct mixing of the flyrnash with AMD at pre-determined FA:AMD ratios. Depending on the FA:AMD ratio,rnneutral and alkaline pH levels were achieved. Reduced heavy metal and sulfaternconcentrations with a corresponding decrease in conductivity were observed postrnco-disposal. The successful co-disposal of AMD with fly ash provides a technologyrnsuitable for neutralization and amelioration of AMD.