STUDY OF ACID MINE DRAINAGE GENERATION THROUGH COLUMN LEACH TEST AT BATU HIJAU MINE SITE PT NEWMONT NUSA TENGGARA

• Main Author: SIBARANI (NIM : 22110022), LASMARIA
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/20248
• Institution: Institut Teknologi Bandung

The development of mining technology in recent decades and the high price of metals has significantly increased the number of open-pit mining. This in turn will increase the amount of pit lakes. Pit lake can use as a water resource or becomes environmental problems depends on its water quality. Success in predicting water quality that will happen to be a decisive thing in determining the impact of management strategies that may occur. This study aimed to examine the generation of acid mine drainage in the Batu Hijau pit based on Field Column Leach Test (FCLT). Simulation to determine <br /> <br /> <br /> <br /> <br /> water quality made in two ways. First is by mixing the water quality of FCLT which represent rock types exposed in the FCLT with consideration of collection time of water in pit sump. In this study the approached water quality is the water quality in pit sump formed with an estimated time for 6 months. Water quality is approached by mixing leachate water quality FCLT at the same time. From the results of mixing using PHREEQCI2 found that the pit sump water quality can be approximated by the difference in pH of less than 0.01. Thus the quality of water in sump pit can be approximated by mixing leachate water quality of FCLT with the proportions according to the type of rock exposed. The second way is to use the rate of pyrite oxidation. In this study it was found <br /> <br /> <br /> <br /> <br /> that the rate of pyrite oxidation is calculated based on sulphate released, change with time. Changes that occur forms a bell shape graph. The pyrite oxidation rate <br /> <br /> <br /> <br /> <br /> at the initial of the reaction is quite slow due to the slow reaction rate of pyrite at high pH. As pyrite oxidation proceeds, the pH decreases in a series of steps and at some stage will drop to 2-3. At this stage the pyrite oxidation rate will increase significant as the oxidation by ferri ion come to play and also increased in the population of bacteria. At some stage pyrite oxidation rate will reach a maximum, thereafter decreasing as the quantity of readily oxidizable pyrite decreases. Pyrite oxidation rate will continous to decrease and the leachate returns to a near neutral <br /> <br /> <br /> <br /> <br /> pH. The rate of oxidation of pyrite in the first seven years were calculated in this study is used together with the amount and type of minerals in the rock samples were carried out in this study has been able to determine water quality of FCLT leachate in the 15th year and has been verified by the measurement at the same time. Thus the expected rate of oxidation of pyrite in the first seven years will be used to determine the water quality in the pit lake in the future.