Underground mining is a discipline that deals with the extraction of ore below the earth’s surface in a manner that permits optimum return on investment while upholding the safety of miners and the integrity of underground openings. Mining methods used underground should be based on elaborate drilling and sampling sufficient enough to identify the grade and extent of the ore.
Types of underground mine openings
Entry into an underground mine may be through a shaft, an adit (a horizontal or near-horizontal entrance to an underground mine), or a decline. Choosing which type of entry to use will depend on determining the easiest access to the ore while minimizing the waste rock that needs to be excavated to extract the ore.
Accessing the ore
Modes of access include slope, drift, and shaft mining. Slope mines usually start in a valley bottom with a tunnel sloping down into the ore to be mined. Drift mines enter horizontally into the side of a hill. Shaft mines are the deepest mines, and require an elevator that reaches from the surface down to the ore. Underground mine rail cars are often employed to transport extracted ore to be hoisted to the surface.
Ventilation is a necessary aspect of underground mining. Without it, toxic fumes from blasting and diesel equipment will remain in the shafts and tunnels. In deep hot mines, ventilation is also required for maintaining workable temperatures in tunnels. Ventilation raises are created to provide ventilation for mining workspaces, and can be used as emergency escape routes depending on the build.
Difference between Longwall and Room & Pillar mining
Longwall and Room & Pillar mining are two popular underground mining methods. In Room & Pillar mining, a network of “rooms” are cut into seams. Pillars are left in place to support the roof in a regular pattern while the rooms are mined out. On the other hand, Longwall mining involves the use of mechanized shears to cut and extract ore at the face of the mine. Extracted ore is then dropped onto a chain conveyor system that will ultimately take the ore to the surface. Temporary hydraulic-powered roof supports are used instead of pillars to hold the roof up.
Investing in the development of new mines can be attractive for companies when metal prices ensure profitable operations. When planning for the transportation of ore within a new mine, it is important to partner with a trusted manufacturer of underground rail cars and other conveyance equipment such as Wabi Iron & Steel Corp.
Underground Mining Methods, Inside Metals
Methods of Mining, University of Kentucky