Effects of Nickel Mining Activities on Water Quality

Abstract

Acid Mine Drainage (AMD) originates from the sulphide mineral oxidation in the presence of water and oxygen, and to some extent bacteria, yielding sulphuric acid. The acid generated mobilizes some metals resulting in their increased bioavailabilities, creating a hazardous environment for aquatic animals and plants. The groundwater quality emanating from adjacent mine sites is a useful tool for measuring AMD. The purpose of this study was to determine extent of mine drainage from an active nickel mine and to develop mitigation. Major mining pollution sources were identified for constant monitoring. Recommendations for possible remediation and abatement of AMD were made. Several liquid samples were taken from selected sites along two streams, which flow out of the mining complex. Eight water samples were collected once a month from June to October. pH and conductivity were immediately measured followed by determination of Cu, Fe, Ni, sulphates, Total Suspended Solids (TSS) and Total Dissolved Solids (TDS). Elevated concentrations of sulphate, high conductivity and TDS were observed indicating the presence of AMD. An increase in sulphate concentration, TDS and Conductivity levels for the Community Rivers was observed. This was caused by the water flowing from the nickel mine. The quality of the natural river water was grossly affected. A passive treatment strategy would need to be developed. For the treatment process to succeed, a complete characterisation of the contaminated mine drainage is needed. Topsoiling and revegetation are other cheaper methods that can be used to reduce the extent of sulphide oxidation.