Feasibility Of Coal Ash Backfilling In Opencast Mines Using The Darcy Column Experiment.

The generation of acid mine drainage (AMD), as a result of mining activities, has led to the degradation of groundwater quality in many parts of the world. Coal mining, in particular, contributes to the production of AMD to a large extent in South Africa. Although a vast number of remediation methods exist to reduce the impacts of AMD on groundwater quality, the use of a coal fly ash monolith to act as a reactive and hydraulic barrier has not been extensively explored. This study, therefore, aims to investigate how different ways of packing ash affect the hydraulic conductivity of ash and influence leachate quality when acid-mine drainage filters through the ash. Coal ash is highly alkaline due to the existence of free lime on the surface of the ash particles. Previous studies that investigated alternative uses of coal ash, particularly in AMD treatment, suggest that coal ash has the potential to neutralise pH in acid water and remediate acidic soils. To test the effects of different packing methods of coal ash on the hydraulic conductivity and quality of acid mine leachate flowing through it, several Darcy column tests will be conducted. During the course of these experiments, the following parameters will be measured, electrical conductivity, pH discharge, lime (CaCO3) and selected elements of environmental concern.