GEOCHEMICAL MODELLING OF LAYERING SCENARIO AMONG POTENTIALLY ACID FORMING (PAF) AND FLY ASH WITH MIX MODELLING AND FORWARD-MIX MODELLING APPROACHES

• Main Author: Desdita Komari, Sri
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69131
• Institution: Institut Teknologi Bandung

Acid Mine Drainage (AMD) is formed through a series of chemical reactions and biological activities of sulfide-minerals contained rock exposed due to mining activities. The formation of AMD is one of the main environmental problems in mining industry. One of options to prevent AMD is by encapsulation or coating with a dry cover system. In general, dry cover uses Non Acid Forming (NAF) materials which can be an option in the dry cover system. The purpose of this study was to determine the geochemical modelling based on the mix solution modeling and forward-mix modeling of PAF and Fly Ash layering scenarios using PHREEQC software and to calculate the rate of Pyrite Oxidation of the two approaches. The data used in this study were secondary data from the kinetic test result using the Free Draining Column Leach Test (FDCLT) method, the static tests result, and the mineralogy and elemental tests result. Based on the results of geochemical modeling, it can be concluded that forward-mix modeling was the chosen approach model which have the closest result to the kinetic test in terms of pH and elemental concentration. As for the rate of pyrite oxidation, the mole transfer approach resulting from the forward-mix modeling gives closest value compared to the results of the kinetic test. This result is confirmed by the calculation of the ratio of moles of Fe and moles of Sulphate from the forward-mix modeling which gives a value of 1: 1.45 from an ideal condition of 1:2.