Two dimensional computational fluid dynamics model of pollutant transport in an open pit mine under Arctic inversion

Thesis (M.S.) University of Alaska Fairbanks, 2012A better understanding of the microscale meteorology of deep, open pit mines is important for mineral exploitation in arctic and subarctic regions. During strong temperature inversions in the atmospheric boundary layer--which are common in arctic regions during the winter--the concentrations of gaseous pollutants in open pit mines can reach dangerous levels. In this research, a two dimensional computational fluid dynamics (CFD) model was used to study the atmosphere of an open pit mine. The natural airflow patterns in an open pit mine are strongly dependent on the geometry of the mine. Generally, mechanical turbulence created by the mine topography results in a recirculatory region at the bottom of the mine that is detached from the freestream. The presence of a temperature inversion further inhibits natural ventilation in open pit mines, and the air can quickly become contaminated if a source of pollution is present. Several different exhaust fan configurations were modeled to see if the pollution problem could be mitigated. The two dimensional model suggests that mitigation is possible, but the large quantity of ventilating air required would most likely beimpractical in an industrial setting.1. Introduction -- 1.1. Scientific rationale -- 1.2. Air inversion -- 1.3. Previous modeling approaches -- 1.4. Solution approaches -- 1.5. Proposed remediation measures -- 1.6. Scope of this research -- 1.7. Work plan -- 2. Data collection -- 3. Model development -- 3.1. Fundamental transport equations -- 3.2. Cell zone and boundary conditions -- 3.3. Meshing -- 3.4. Discretization -- 3.5. TurbulenceModeling -- 3.6. Geometry and mesh creation -- 3.7. Wind flow in open pit mines -- 3.8. Development of an atmospheric inversion -- 4. Pollutant transport in an open pit mine under Arctic air inversion -- 5. Mitigation of pollutants -- 5.1. Helicopter -- 5.2. Exhaust fan: 142 m³/s -- 5.3. Exhaust fan: 556 m³/s -- 5.4. Exhaust fans: multiple fans, multiple sources (142 m³/s) -- 5.5. Exhaust fans: multiple fans, multiple sources (284 m³/s) -- 6. Summary, conclusions, and recommendations for future work -- 6.1. Summary and conclusions -- 6.2. Future work -- 7. References