Underground Coal Mining — Summer 2025

Write the rank of coal in terms of increasing moisture content.

Explain the term shaft, Incline and Adit with neat sketch.

Discuss panel system of mining with neat sketch? How panel size is decided in Bord and Pillar method of working? Explain briefly.

Name the subsidiary of coal India limited (CIL) with their headquarter name.

Explain the basic principle of bord and pillar method with neat sketch.

Discuss the method of development of bord and pillar mining by blasting off the solid. Also draw the sketches of patterns of blast holes.

Discuss the procedure to establish the design of a new longwall face or district.

Write the applicability conditions of longwall method of mining.

Explain theories of origin of coal in detail.

Calculate number of pillar in the panel if output per day from the panel is 340 tonnes, number of working days in a month is 26, incubation period of coal seam is 6 month and percentage recovery in the panel is 78 %. Assume width of square pillar is 22.5 m, height of pillar is 3 m and density of coal is 1.4 tonnes/m3.

When do we need to support mines and why?

What are the variants of longwall face layouts? Explain with neat sketch.

Discuss the principles of pillar extraction techniques? Also Explain the pillar extraction techniques with neat sketch.

Draw a neat sketch of a longwall face & name the elements.

How factor of safety of pillar is determined? Explain with one example.

Explain longwall retreating and advancing method with neat sketch. Also write the advantages of longwall mining.

What are the ideal characteristics of stowing material used in stowing?

How to calculate percentage of extraction during development & depillaring? Explain with one example.

Discuss the process of hydraulic stowing with a neat sketch.1

Write the classification of coal seam as per thickness, Depth and Inclination.

State the advantages and disadvantages of mechanical stowing.

Discuss the operations involved & facilities provided in a mixing chamber of sand stowing.

What do you mean by cyclic and non-cyclic operations?

What do you understand by roof bolting? Also explain its principle of action and functions.

Give a brief idea about hydraulic and friction props.