Lesson 4- Underground Mining Method Flashcards
Different underground mining methods can be used in application to coal mining. The approach will vary on various parameters such as the _____, ______, and the _____ of the surrounding rock.
thickness, dip and the competency
_______ is a highly mechanized underground mining system for extracting coal. In this method, a layer of coal is selected and blocked out into an area known as a ______, usually ________ x __________ and is set with a mining equipment, typically __________ _________ and ______________ consisting of a coal shearer mounted on conveyor operating underneath a series of self-advancing hydraulic roof supports.
Longwall Mining, panel, 3000 m long X 250 m wide, 150-250m in width and 1.5 to 3 meters high
_________ are excavated along the length of the _______ to provide access
and to place a conveying system to transport material out of the mine.
Passageways, panel
__________ are also constructed from the passageways along the width of the panel to extract the coal between entry tunnels.
Entry tunnels
The system may advance into an area of coal, or more commonly, retreat back between development tunnels (called “_______”) allowing the roof behind the supports to collapse in a planned and controlled
manner.
gate roads
This mining method accounts for less than 1% of deep coal production. This technique involves the use of a continuous mining machine with moveable roof supports, similar to longwall.
Shortwall Mining
The continuous miner shears coal panels _______ and more than a ________ long.
150–200 feet wide, half mile
This technique is designed and used primarily for mining flat-lying seams, or tabular orebodies like coal and is most advantageous for shallow orebodies –as a means of preventing surface subsidence. This method is well adapted to mechanization and is sometimes referred to as continuous mining.
Room and Pillar Mining
In room and pillar mining, _______ are left in place in a regular and systematic pattern as support of the roof while the _______ are mined out.
pillars , rooms
Many room and pillar mines, the pillars are taken out starting at the farthest point from the stope
access, allowing the roof to collapse and fill in the stope. This process is called ___________.
retreat mining
This is an older practice of coal mining that uses explosives such as dynamite to break up the coal seam and accounts for less than 5% of total underground production in the U.S. today.
Blast Mining
Chronic lung diseases, such as _____________ were once common in miners, leading to reduced life expectancy. In some mining countries black lung is still common, with 4,000 new cases of black lung every year in the US (4 percent of workers annually) and 10,000 new cases every year in China (0.2 percent of workers). Rates may be higher than reported in some regions.
pneumoconiosis (black lung)
Build-ups of a hazardous gas are known as _______ , possibly coined from the German word _______ which means steam or vapor.
damps, “Dampf”
A mixture of carbon dioxide and nitrogen in a mine can
cause suffocation, and is formed as a result of corrosion in enclosed
spaces so removing oxygen from the atmosphere.
Black damp
Consists of carbon
monoxide, carbon dioxide and nitrogen and forms after a mine
explosion.
After damp
