When it comes to mining coal, there are two processes by which coal can be removed from the ground: surface mining, or underground mining. In Australia, the majority of coal mining is done via the opencast method, although often the method of choice is dependent on certain characteristics of the coal deposit 1.
The opencast, also referred to as the open-pit method, is the ideal technique when the coal seam is close to the surface. Extremely efficient, opencast mining can recover nearly 90% of the coal seam. In this process, explosives are used first in order to break up the top layer of soil and rock, also referred to as overburden. After the soil and rock has been broken down, overburden is removed and the underlying seam of coal is uncovered. This coal seam is mined in strips by means of drilling and splintering. After an opencast mine has been mined to its full potential, the mine is backfilled and shaped with the same soils that were originally taken from it1. This land can then be repurposed for a variety of uses such as grazing land, a community park, or a commercial site. Conveyors play an important role in the open-pit coal mine, as they help in transporting and loading the coal.
When a coal seam is too deep to efficiently mine the coal from the surface, underground mining techniques are used. The underground method of coal mining currently utilizes two main techniques: room and pillar mining, and longwall mining 1.
Room and pillar mining involves cutting a system of rooms within the coal seem. Pillars are left in order to support the roof of the cut into coal seem. In a secondary mining method, called retreat mining, coal is systematically collected from the pillars, allowing the mine to close in behind them2. This type of mining can be extremely dangerous.
Longwall mining involves extracting the coal from an entire section of the seam using a specialized machine that loosens up the coal, allowing it to fall and be carried away by a conveyor system. Hydraulic roof move along as the operation progresses, allowing the previous area to close in in a controlled manner2.
Whether it is underground mining, or surface mining, the use of quality conveyors in the coal industry is imperative to maintaining efficiency. FEECO has been involved with the coal industry for decades, providing superior quality conveyor systems, bucket elevators, belt trippers, and belt plows.
Sources:
(1) World Coal Association
(2) Wikipedia