ABSTRACT
Acid mine drainage (AMD) is a serious problem in many coal and mineral mines. Over the past 50 years, many researchers have developed static tests that play an essential role in preventing AMD. In Indonesia, static tests are conducted using two methods: acid-base accounting (ABA) and net acid generation (NAG) tests. On an operational scale, mining companies commonly use the NAG test because it is simpler and faster than ABA. The NAG test is performed using hydrogen peroxide at a concentration of 15% as a strong oxidizing agent, according to the ARD Test Handbook and Indonesian National Standard (SNI). However, since 1990, an Indonesian coal mining company, PT Kaltim Prima Coal, is conducting NAG tests using 7.5% hydrogen peroxide. In the present dataset, we compared the results of NAG tests obtained using 7.5% and 15% hydrogen peroxide for 564 rock core samples. The dataset also shows the behavior of the NAG solution for each representative rock characteristic-including the concentrations of Fe, Mn, and SO4, oxidation reduction potential (ORP), conductivity, total dissolved solids (TDS), and temperature-during the test. This dataset can be useful for researchers to investigate the differences in the NAG test when 7.5% and 15% hydrogen peroxide are used, as well as to understand the oxidation behavior of sulfide minerals when hydrogen peroxide is used as a strong oxidizing agent for AMD.
ABSTRACT
Static tests of acid mine drainage potential are an important part of mining water management. Net acid generation (NAG) test is widely used in Indonesian coal mines because of its convenience. This test uses H2O2 to oxidize sulfide minerals within rock samples to determine their net acid-forming capacity. This study aimed to determine the difference between H2O2 at concentrations of 7.5% (the standard in several Indonesian coal mines) and 15% (the standard of the Acid Rock Drainage Test Handbook and Indonesian National Standard) in categorizing rocks as potentially acid-forming and non-acid-forming and in terms of NAG solution characteristics. A total of 564 rock samples collected from two Indonesian coal mining sites were analyzed using pH, NAG, total sulfur, and acid-base-accounting tests. The results of the study showed that there was no significant difference in rock classification or the behavior of contaminants in the NAG solution between 7.5% and 15% H2O2. The characteristics of sulfide minerals in Indonesian coal mines were the main factors influencing the results of the NAG test and behavior of contaminants in the NAG solution. Therefore, H2O2 at a concentration of 7.5% can be used in Indonesian coal mines with relatively low total sulfur concentrations (<5%) and minerals in framboidal form.
ABSTRACT
Encapsulation is a typical method used to prevent potential acid mine drainage (AMD) in overburden piles. In this method, Potentially Acid-Forming (PAF) material is covered with either Non-Acid-Forming (NAF) material or alkaline material to minimize water infiltration and/or oxygen diffusion through rock pores. The physical and chemical characteristics and thickness of the NAF material layer are critical factors affecting the successful prevention of AMD. Therefore, this study evaluated the method of NAF material layering using laboratory-scale column leaching tests. NAF layers with a ratio of 25 and 50% were used to cover PAF material containing pyrite and jarosite sourced from the Sangatta and Bengalon mining areas, East Kalimantan. The physical and chemical characteristics of leachate collected from samples watered on a weekly wet-dry cycle were analyzed by kinetic tests over a period of 23 weeks. The results showed a trend of increasing pH values and decreasing sulfate and metal concentrations in the leachate. This study shows that NAF layering is an effective method to prevent or minimize the generation of AMD.
