LONG TERM KINETIC STUDY OF ACID ROCK DRAINAGE FORMATION FROM PT. FREEPORT INDONESIA'S TAILINGS

• Main Author: DEWI YUNIATI (NIM : 22108018), MUTIA
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/20341
• Institution: Institut Teknologi Bandung

Acid rock drainage is one of some important environmental problems in the mining and mineral processing industries. Mining activities cause rocks to be exposed to the surrounding environment. These activities may cause the rocks containing sulphide minerals to be exposed to the air and react with water, then sulphuric acid is produced and acid rock drainage occurs. One of the sources of acid rock drainage is tailings, particles of rock remaining after the economically valuable mineral are removed from the ore. PT. Freeport Indonesia (PT.FI) produces millions ton of tailings per year, which may impact the environment <br /> <br /> <br /> <br /> <br /> especially by contaminating the water. Therefore the research about geochemical characteristics and factors influencing acid rock drainage formation from tailings <br /> <br /> <br /> <br /> <br /> was needed to minimize its effect. The rates of reaction and potential of acid rock drainage formation were also determined. In this research, the result of long term <br /> <br /> <br /> <br /> <br /> kinetic column leach test of PT. Freeport Indonesia’s tailings samples was investigated in two conditions, without limestone addition and with limestone addition. The results show that tailings without limestone addition have the potential to produce low capacity acid rock drainage, with acid releasing rate of 0.88 g/t/d for 72 years and acid neutralizing releasing rate of 4.45 g/t/d for 16 years. This formation is accelarated by the existence of Thiobacillus ferrooxidan bacteria and ferric iron (Fe3+) from magnetite and hematite. Whereas, the sample with limestone addition does not have potential to produce acid rock drainage, but the addition only neutralizes the acid for 35 years. This ineffectiveness is influenced by the difference of tailings and limestone particles size distribution in <br /> <br /> <br /> <br /> <br /> the blending process, which have the effect on sulphide mineral oxidation and carbonate mineral dissolution process. During the acid rock drainage formation, <br /> <br /> <br /> <br /> <br /> the pH and total alkalinity were found decreasing; and total acidity, sulphate, calcium, magnesium and dissolved metals were found increasing.