Surface or opencast coal mining:

Surface or opencast coal mining:

Coal has been used worldwide as a fuel for centuries. Around 1800 coal became the main energy source for the Industrial Revolution. The expanding railway system of various countries lead development of coal driven power steam trains. Britain developed the main techniques of underground coal mining. In fact, the first industrial revolution began in Britain in the 1700s, and later spread to almost every part of Europe, North America, and Japan, was based on the availability of coal to power steam engines. Since then coal has been very important fuel for us. Therefore, since its introduction, coal mining has played an intricate role in the economic stability.

Coal mining is the removing of coal from the earth by mining safely and economically. Coal is used for power generation, for making steel and for other industrial activities including domestic heating. When coal is used for fuel in power generation, it is referred to as steaming or thermal coal. Coal that is used to create coke for steel manufacturing is referred to as coking or metallurgical coal. The most economical method of coal extraction from coal seams depends on various factors such as, depth, thickness of coal strata, quality of the seams, geology of the coal bearing strata and environmental factors of the area being mined. Coal mining processes are generally differentiated by the method by which a particular seam is to be mined, i.e., whether they are to mined by the surface operation or by underground operation. Many coals extracted from both surface and underground mines require washing in a coal preparation plant for reduction of ash to increase its heat value.

Surface coal mining: When coal seams are near to the surface, it may be economical to extract the coal using surface mining method (also referred to as open cast or open pit). Lots of heavy earth moving machineries are employed in this method. The overburden, i.e., waste material overlaid coal seam, is excavated before excavation of coal. A list of major opencast mining machineries employed for coal and ore mining are given below. These are used for high production in mines:

(a) Dragline - Dragline excavation systems are heavy equipment used in civil engineering and surface mining. A dragline bucket system consists of a large bucket which is suspended from a boom (a large truss-like structure) with wire ropes. The bucket is maneuvered by means of a number of ropes and chains.

(b) Shovels - Shovels are heavy equipment used in civil engineering and surface mining. These are hydraulically operated. For mining purpose the capacity employed is very large.

(c) Dumpers - A dumper is a vehicle designed for carrying bulk material or blasted coal or minerals. In mining, dumpers are loaded by a Shovel. After loading dumper is moved to the unloading site where the blasted coal or minerals are unloaded with the help of hydraulic jack.

(d) Drilling machines – Drill machines are for drilling holes for blasting purposes.

(e) Loaders - A loader, also called a front loader, front end loader, bucket loader, is a type of tractor, usually wheeled, that uses a wide square tilting bucket on the end of movable arms to lift and move material. Loaders are used mainly for uploading materials into trucks / dumpers.

(f) Air Compressors – Compressors are used in mining with drilling machines. Small dia. Jack hammer holes are drilled with the help of air compressors.