GEOCHEMICAL CHARACTERIZATION OF ACID MINE DRAINAGE FORMING OF ARGILIC AND CHLORITIC ALTERATION IN HIDROTHERMAL DEPOSIT
Sulfide mineral is the main factor in Acid Mine Drainage (AMD) generation, which can be formed in mineralization process derived from hydrothermal fluids, as occurred in High Sulphidation Epithermal (HSE) deposits. The hydrothermal fluid interacts with rock causes a change of mineralogical, texture,...
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| Format: | Theses |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/29920 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Sulfide mineral is the main factor in Acid Mine Drainage (AMD) generation, which can be formed in mineralization process derived from hydrothermal fluids, as occurred in High Sulphidation Epithermal (HSE) deposits. The hydrothermal fluid interacts with rock causes a change of mineralogical, texture, or chemical content of the rock or known as hydrothermal alteration. Samples in this study are from argilic and chloritic alteration zones, which the argilic zone characterized by clay minerals such as kaolinite, illite and smectite. In the other hand, chloritic zones characterized by chlorite, carbonate, albite and epidote minerals. Differences in the alteration mineral assemblages in those two alteration zones result in differences in mine acid water characteristics associated with geochemical reactions such as pyrite oxidation, dissolution of sulfate minerals and carbonate minerals. <br />
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Geochemical characterization performed on samples were static test, kinetic test, and leachate chemical quality test and mineralogical and elements test. The results of geochemical characterization shows that AR-1, AR-2, CH-1 and CH-2 samples have the potential to form acid (PAF), which indicate that hydrothermal alterations cannot define the classification of the samples based on their AMD generation. <br />
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Geochemical modeling was performed by using inverse and forward modeling in PHREEQC software to calculate the geochemical reaction and the reaction rate of minerals. The result shows that pyrite oxidation reaction, sulfate dissolution (gypsum) reaction and carbonate neutralizing reaction (calcite) ranging from 1.17x10-10 mol m-2 s-1 to 8,61x10-8 mol m-2 s -1 , respectively. Reaction rate is also used in the prediction of time pyrite depletion by using exponential decay of first order reaction. Result shows pyrite depletion time for AR-1, AR-2, CH-1 , CH-2 are 31.2 years,1.08 years, 1.15 years 54 years, respectively.. The difference is due to only by differences in the rate of pyrite oxidation reaction but also the difference in the amount of initial pyrite present in the sample obtained from the total sulfur value in the static test results of each sample where it was assumed that the overall sulfur concentration was derived from the oxidation of the pyrite mineral. <br />
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