Abstract
Geochemical characteristics and the increase of total reactive surface area of the sulphide-bearing waste rock due to weathering processes at dumping area are expected to enhance the oxidation of sulphide minerals, commonly present as pyrite (FeS2), leading to acid mine drainage (AMD) generation. Having investigated the geochemical characteristics of the waste rock at the surface layer (0 - 200 cm depth) of Pit J (2 years-old) and Sangatta North (10 years-old) dumping areas, the study indicated that the oxidation of sulphide-bearing waste rock uniformly occurred and it was influenced by the physical weathering as the forerunners of chemical weathering. The formation of clay minerals was then considered to have a potency of being oxygen and water barrier which consequently would reduce the AMD generation. In addition to that, an investigation of in situ waste rocks from Melawan area was also conducted. The results of investigation indicated that the rocks were physically easy to break down hence increasing the total reactive surface area for chemical reaction upon exposed to the climatic condition, and should be considered as an important factor in determining the processes of AMD generation afterward at dumping area.
