1. An airflow of 25 m3/s and radon daughter concentrations of 0.2 WL passes a seal from which issues a leakage flow of 0.4 m3/s at 150 WL. Determine the radon daughter concentration in the downstream airflow.
2. Describe the various methods of methane drainage available to drain gas for longwall mining operations.
3. In the case of cross measures methane drainage of longwall operations what factors influence the spacing of drainage boreholes?
4. On retreating longwall coalfaces active ventilation of the goaf is undertaken, why is this. Detail three methods of ventilating the goaf in such conditions.
5. Briefly describe the methods used to control radiation in uranium mines.