TY - GEN
T1 - Preliminary results of the water flow modeling in an acid drainage generating waste rock pile located at the uranium mining site of Poços de Caldas - Brazil
AU - Franklin, Mariza
AU - Fernandes, Horst
AU - Yeh, George
AU - De Azevedo, José Paulo S.
PY - 2006
Y1 - 2006
N2 - The first uranium production center in Brazil began operation in 1982. After 13 years of a non-continuous operation, the mining activities were suspended definitively. Uranium was extracted by open pit mining. Operations gave rise to approximately 12.4×106 m3 of waste rock, while the mill process generated a volume of approximately 2.39×106 m3 of tailings. Regardless the fact that some studies developed in this area exist, a well defined plan of action, aimed at the remediation and rehabilitation of the site, has not been implemented yet. The main sources of pollutants to the environment are the tailings dam, the waste rock piles and the open pit. Pyrite oxidation was found to be the driving force in the leaching of metal and radionuclides into environment. It was estimated that acid drainage generation will last for 600 and 200 years from the waste rock and tailings respectively. Accurate prediction of the release rate of metal and radionuclides from these sources and their transport in the subsurface is a critical factor to the assessment of environmental impact and to the development of effective remediation strategies. In prevailing practice, the source term is evaluated using the dissolution rate of waste form and the solubility of radionuclides. The fate of pollutants is addressed by the use of Kd-based "reactive" transport models. This standard practice has obvious shortcomings, mainly because it can not produce a realistic representation of the system under study. The alternative to overcome these shortages is using more sophisticate models that could represent real complex problems. Reactive transport codes are powerful tools in the evaluation of coupled thermal-hydrological-chemical processes and in the prediction of the long-term performance of remediation strategies. The difference between the predictions from these two approaches can be as high as several orders of magnitude. Generally, conventional approaches produce predicted values higher than the measured ones. On the other hand, the use of reactive transport model requires a good knowledge of the simulated hydrogeochemical system, along with the choice of appropriated algorithms that can represent the most important processes.
AB - The first uranium production center in Brazil began operation in 1982. After 13 years of a non-continuous operation, the mining activities were suspended definitively. Uranium was extracted by open pit mining. Operations gave rise to approximately 12.4×106 m3 of waste rock, while the mill process generated a volume of approximately 2.39×106 m3 of tailings. Regardless the fact that some studies developed in this area exist, a well defined plan of action, aimed at the remediation and rehabilitation of the site, has not been implemented yet. The main sources of pollutants to the environment are the tailings dam, the waste rock piles and the open pit. Pyrite oxidation was found to be the driving force in the leaching of metal and radionuclides into environment. It was estimated that acid drainage generation will last for 600 and 200 years from the waste rock and tailings respectively. Accurate prediction of the release rate of metal and radionuclides from these sources and their transport in the subsurface is a critical factor to the assessment of environmental impact and to the development of effective remediation strategies. In prevailing practice, the source term is evaluated using the dissolution rate of waste form and the solubility of radionuclides. The fate of pollutants is addressed by the use of Kd-based "reactive" transport models. This standard practice has obvious shortcomings, mainly because it can not produce a realistic representation of the system under study. The alternative to overcome these shortages is using more sophisticate models that could represent real complex problems. Reactive transport codes are powerful tools in the evaluation of coupled thermal-hydrological-chemical processes and in the prediction of the long-term performance of remediation strategies. The difference between the predictions from these two approaches can be as high as several orders of magnitude. Generally, conventional approaches produce predicted values higher than the measured ones. On the other hand, the use of reactive transport model requires a good knowledge of the simulated hydrogeochemical system, along with the choice of appropriated algorithms that can represent the most important processes.
UR - http://www.scopus.com/inward/record.url?scp=84868613000&partnerID=8YFLogxK
U2 - 10.21000/jasmr06020611
DO - 10.21000/jasmr06020611
M3 - 會議論文篇章
AN - SCOPUS:84868613000
SN - 9781622760855
T3 - 7th International Conference on Acid Rock Drainage 2006, ICARD - Also Serves as the 23rd Annual Meetings of the American Society of Mining and Reclamation
SP - 611
EP - 622
BT - 7th International Conference on Acid Rock Drainage 2006, ICARD - Also Serves as the 23rd Annual Meetings of the American Society of Mining and Reclamation
PB - American Society of Mining and Reclamation
T2 - 7th International Conference on Acid Rock Drainage 2006, ICARD 2006, Also Serves as the 23rd Annual Meetings of the American Society of Mining and Reclamation
Y2 - 26 March 2006 through 30 March 2006
ER -