This question was fairly popular among the candidates and their performance was poor. A good number of the candidates gave definition of Mining for that of a mine. A mine is an opening made in the earth for extracting useful minerals.

The following should be noted about the room and pillar method of coal mining:

• It involves the extraction of coal by creating rooms
• Pillars of coal are left unremoved at regular intervals in between the rooms to give support
• After the removal of coal, crosscuts are made at right  angles to the general direction of mining
• The size of the pillars that is used in supporting the roof should be the same dimension
• The rooms and cross cut could be created using two system namely- the conventional mining system and continuous mining system.
• The conventional mining method involves creation of kerf/slots at the floor on the surface of the coal
• Holes are drilled into which permissible explosives are used to blast off the coal
• Loading machines are used to evacuate the blasted pieces of coal
• The main entry point is created on evacuation of the blasted coal
• The continuous method involves the use of a highly integrated machine
• The machine rips off coal from the mine face
• Broken coals are rolled automatically to an inbuilt conveyor belt which rolls them to the collection point at the rear (back) of the machine.
• Proper arrangement are made for mine ventilation
• Provisions are made for seepage water
• Care is taken to give the required support for the roof of the mine

The following should be noted about the longwall method of coal mining:

• Unlike the room-and-pillar method, this method leaves little coal unmined in the pillar.
• Large panels of coal are created
• The faces are mined in slices back towards the shaft
• Coal is usually skimmed from the face using a shearer machine
• The face conveyor moves the skimmed fragments of coal to the permanent conveyor in the main entry.
• Massive hydraulic jacks are used to support the roof of the mine
• The face conveyor and powered support are repositioned as the mining progresses
• The roof of the mine is allowed to collapse in a regulated manner at the gob/goaf