Long-term Characteristics of Tailing from PT Freeport Indonesia based on Column Leach Kinetic Test

• Main Author: ANDARANI (NIM : 22109316), PERTIWI
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/20390
• Institution: Institut Teknologi Bandung

One of the important issue in mining industries is acid rock drainage. Tailing could become source of acid rock drainage as it contains sulphide minerals. In this study, The main concern of this study is tailing which was generated from a copper-gold ore processing plant of PT Freeport Indonesia, before ModADA deposition. To increase the ratio of ANC/MPA (Acid Neutralizing <br /> <br /> <br /> Capacity/Maximum Potential Acidity), limestone is added to the tailings. The objective of this study is to investigate the characteristics of the tailings in the <br /> <br /> <br /> long run, including the tailings with limestone addition and without addition. In this study, the data of column leach kinetics test were used to estimate the reactions that might occur according to saturation indices of minerals and transfer mol profile (back-analysis). To estimate these parameters, PHREEQC 3:00 software with WATEQ4f database was used. Based on column leach test, pH of tailing sample without limestone addition will <br /> <br /> <br /> become acid after 25th month , while the tailing sample with limestone addition had stable pH over the time. Therefore, sulphide minerals need approximately a year to be oxidized effectively and generate much more acidity. This could be due to weathering of sulphide minerals in ore deposit need more time compared to <br /> <br /> <br /> sulphide minerals weathering in coal deposit. Based on transfer mol on pyrite, it could be estimated that the rate of pyrite oxidation was about 6,7 - 17 grams/tons <br /> <br /> <br /> tailing/day (60th – 66th month) then started to decline after 80th month. The effect of limestone addition could be seen after approximately a year (25 month of leaching period). Limestone is important to maintain pH near neutral, even after one year period of leaching has been passed. According to moles transfer profiles, more limestone tended to react in the beginning of leaching <br /> <br /> <br /> period (until 76th month) compared to after 76th month (2,78x10-8 – 1,3x10-7 moles/kg leachate) because saturation index of limestone is relatively smaller <br /> <br /> <br /> than carbonate minerals, hence, it tends to react more in the beginning of leaching period due its high solubility.