The Acid-Base Accounting (ABA) of Overburden Rock to Predict Acid Mine Water in Kasai Coal Mining, Indonesia

Abstract

The Acid-Base Accounting (ABA) and TCLP methods from overburden samples collected from the coal mine in Kasai were undertaken to predict pre-mining acid mine water quality. Maximum potential acidity (MPA), acid neutralization capacity (ANC), net acid generation (NAG), net acid producing potential (NAPP) and ANC/MPA ratios were determined on the Acid-Base Accounting (ABA) protocol. Most of the samples from KS-10, KS-11 and KS-12 show the pH of NAG of overburden ranges from 5.53–7.86 negatively net acid neutralization potential (NAPP). The ANC/MPA ratio varied from 1.09–26.60 and is classified as non-acid-forming except at an interval depth of 7.00–9.00 m in KS-12, where it is classified as uncertainty. The potentially acid mine water detected in KS-39 at an interval depth of 16.00–36.00 m was classified as potential acid forming (PAF), indicated by a positive NAPP, a low ratio of ANC/MPA (below 1.0) and high dissolved metal iron.