1. Enumerate and discuss the physical conditions that must be met in order for a caving mining method can be considered for ore extraction technique.
2. A fall of ground partially caved the heading where a miner worked to within 200 m of the face. The heading is 5 x 5 m in dimension. Several diesel-powered equipment are operating at the heading; a 5 yard, 600 kW scoop, a 200 kW scissor deck, a 300 kW diesel-hydraulic jumbo, and two (2) 75 kW service vehicle. Regulation 854 stipulates that airflow quantity must be at least 0.06 m3/s per kW power of diesel-powered equipment. As a result of the diesel engine emission, Nitrogen Dioxide (NO2) gas steady state inflow approximating 1.10 m3/sec is released in the heading. Because the air that is being used in the heading was recirculated air, the background NO2 concentration exists in the air which is approximately 0.0001%.
Determine the following:
a. The rate of fresh air inflow necessary to maintain NO2 gas levels below the TLV of 5 ppm.
b. Is the volume of air enough to supply the requirements for all the diesel engines at the heading if they will be operating simultaneously? Regulation 854 stipulates that airflow quantity must be at least 0.06 m3/s per kW power of diesel-powered equipment.
c. How long will the miner be theoretically exposed to NO2?