Modified Mining Qualifications Board
EXAMINATION FOR CERTIFICATE OF
COMPETENCY AS AN UNDERMANAGER
QUESTION 1
Markwell Colliery is currently producing 15 000 tonnes of coal per day on a six day roster system. A longwall unit operates three shifts per day - there being two maintenance shifts per week. Development units operate on a 9 unit shifts per day basis (3 Continuous Miners).
The coal seam is very gassy having insitu gas contents between 12 - 19 cubic metres/tonne. Methane gas concentrations are normally 0.5% in main return airways and 1.0% - 1.2% in longwall return airways.
A gas drainage system is in operation at the colliery. During longwall coal cutting operations adverse airborne dust conditions have been experienced.
On the accompanying plan show:
(1) locations of coal production units;
(2) the system of ventilation using the code of signs specified by the Regulation of the Mines Rescue Act;
(3) the air quantities entering each of the ventilating districts measured 100 metres outbye the last completed line of cut-throughs;
(4) the air quantities at each surface entry into the mine;
(5) the calculations for air quantity exhausting from the fan(s), the expected air pressure, air power and motor kilowatts of the fan(s);
(6) the conveyor roadways, transport roadways, return airways;
(7) the calculations of the rate and direction of full dip;
(8) the position of all gas monitoring stations you would require to satisfy your gas management plan.
Model your ventilation plan using Ventsim Visual to determine the duty of the main fan and the quantity of air flowing in all parts of the mine, i.e. roadways, longwall, leakage paths etc. The Ventsim Visual file should be submitted with your completed ventilation plan.