استفاده از ديناميك سيالات محاسباتي و روش ژئوفيزيكي VLF در مدل سازي دو بعدي اكسايش پيريت و توليد زهاب اسيدي در باطله هاي زغال شويي

A Computational Fluid Dynamics Method for two- Dimensional Modeling of Pyrite Oxidation and Pollutant Generation from the Coal Washing Wastes

Coal washing operation results in the generation of large amounts of waste materials containing pyrite. Rapid oxidation of pyrite in the presence of oxygen and moisture produces acid mine drainage. Such acidic drainages cause surface and groundwater pollution. In this study, a very low frequency (VLF) electromagnetic method was used to investigate the likely polluted zones due to leaching from the Alborz Sharghi coal washing waste dump. The geophysical VLF method indicated two low resistivity zones in downstream of the waste dump. A one-dimensional numerical finite volume model was developed using a computational fluid dynamics (CFD) package to simulate pyrite oxidation and pollution generation from the coal washing wastes. For calibration purpose, the modeling accuracy was tested with the results obtained from the field data. A two-dimensional simulation was also performed to predict pyrite oxidation and transportation of the oxidation products from the dump. Pyrite oxidation and acid mine drainage in the waste dump has resulted in a pick concentration of S04 (349 m.e/L) and low pH (pH=3.7) at depth 0.5 m. The elevated concentrations of metals (Fe= 270 m.e/L, Mn= 120 m.e/L, Zn= 375 m.e/L, Cr=25 m.e/L and Co= 10 m.e/L) were found at depth 2 m. Such investigations are necessary for designing an effective environmental management program.