Jawaharlal Nehru Technological University Hyderabad B.Tech III UNDERGROUND MINING TECHNOLOGY Previous Question Paper (March - 2021 - R16)

Continuous Miner (CM) technology relies on a coordinated system of machinery to ensure high-productivity coal extraction. The primary equipment includes:

• Continuous Miner Machine: The core unit equipped with a rotating cutter head that shears coal and loads it onto an integral conveyor.
• Shuttle Cars: Battery or cable-reel powered vehicles that transport coal from the CM discharge conveyor to the feeder breaker.
• Feeder Breaker: A mobile unit that receives coal from shuttle cars, breaks down large lumps, and regulates the flow onto the section belt conveyor.
• Roof Bolters: Independent machines used for systematic roof support installation immediately following the CM advance.
• Section Belt Conveyor: The primary haulage system that transports coal from the feeder breaker to the main trunk conveyor system.
• Ventilation and Dust Control: Auxiliary fans with flexible ducting and water spray systems integrated into the CM to manage methane and respirable dust.

The development of a 3 m thick coal seam using Continuous Miner technology follows a systematic room-and-pillar layout, typically utilizing a multi-heading system (e.g., 5 to 7 headings) to ensure continuous production.

1. Layout Design: Galleries are driven at 6 m width with a 3 m height, maintaining pillar sizes based on depth and strata control requirements. The CM advances in a specific sequence across the headings to allow for cycle time optimization.
2. Cutting Cycle: The CM cuts the coal face in a 'sump and shear' sequence. It sumps into the face at the floor level, then shears upward to the roof to maintain the 3 m height.
3. Haulage Coordination: Two shuttle cars operate in a 'shuttle' pattern, where one car is loaded by the CM while the other travels to the feeder breaker, ensuring the CM does not wait for transport.
4. Roof Support: As the CM retreats from a face after reaching the designated cut depth (usually 6-10 m), the roof bolting machine enters the area to install primary support (roof bolts) before the next cut begins.
5. Ventilation: Line brattice or auxiliary ventilation ducting is extended after every cut to ensure fresh air reaches the face, keeping methane concentrations within safe limits.
6. Sequence of Advance: The CM moves between headings in a predetermined order to balance the distance traveled by shuttle cars and to allow sufficient time for bolting crews to secure the roof in previously cut headings.