IDENTIFICATION OF WEATHERING ROCK IN EVOLUTION OF ACID MINE DRAINAGE FORMING ON LABORATORY-SCALE KINETIC TEST USING GEOCHEMICAL-MINERALOGY-TEXTURE APPROACH: CASE STUDY OF HIGH SULPHIDATION EPITHERMAL DEPOSITS

• Main Author: Syaputra, Rizky
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/68004
• Institution: Institut Teknologi Bandung

Weathering of rocks has an important role in forming Acid Mine Drainage/Acid Rock Drainage (AMD/ARD), which is one of the main environmental problems. AMD arises due to the oxidation of sulfide minerals when interacting with air and moisture. This study focuses on the interaction between physical and chemical weathering of rocks and their effect on the formation of AMD. This study aimed to determine changes in mineralogy and rock texture parameters during laboratoryscale kinetic column testing using a geochemical-mineralogy-texture (GMT) approach. A total of eight rock samples were used consisting of different geological domains from a high sulphidation epithermal (HSE) gold mine in North Sulawesi, Indonesia. The kinetic test column was carried out for 160 to 180 days with flushing cycle intervals of one day, three days, and one week. The kinetic test column results of the HSE material indicate a rapid rate of weathering and oxidation, thus producing a low leachate pH followed by the release of high dissolved metal concentrations. The kinetic test sample’s surface material showed a grain size reduction from coarse (initial condition) to fine (final condition), as well as the appearance of rust color on the material’s surface. Sulfide oxidation increases with increasing rock disintegration, resulting in grain size reduction. This provides access for reactions to occur in minerals due to exposure to air and consequently explicitly affects the quality of the leachate produced. The results of this study indicate that sulfide oxidation is strongly influenced by weathering factors, mineral content, rock texture, grain size, and morphology (crystal form), as well as micro-cracks that develop during the weathering process integrated into the kinetic test column. This factor becomes a significant control on leachate quality as the final result of the AMD formation reaction from materials associated with sulfide minerals.