Mining is an exacavation that produces mineral resources. The mineral
may appear in large deposits known as lodes or narrow veins. The
mineral content of the rock is determined by an assay or chemical
analysis. Any rock that can be mined for profit is known as Ore.
The excavation phases of mining are development and exploitation.
Development is the making of openings to, into and within the body of
the ore. Exploitation is the removal and marketing of the Ore. There
are three processes in this:
Rock Breaking is done with, pick axes, shovels, explosives, drills saws ans augers.
Hauling done mainly with cars that run along rails, or buckets
and other containers hoisted to the surface. Conveyor belts are also
used in some mines.
Ore Dressing is the seperation of the ore from the waste rock or
tailings. Onlya rough seperation is attempted at the mine by hand
picking or mechanical seperation.
Surface Mining
Open Pit Mining is used on large deposits of
mineral, this type of mining requires blasting and the use of heavy
machinery. As the mining continues lage step like sides are created.
These steps or benches are used for loadign of the trucks to carry the
ore away.
Strip Mining is used for shallow deposits of ore. Strips of the
ground called overburden are removed to uncover the deposits. Then the
ore is removed, this is usually done with seams of coal.
Placer Mining is used for extracting materials from a placer a
deposit of sand or gravel with small amounts of of valuable material
usually gold or gems. The minerals are then washed through a box known
as a sluice. the lighter gravel and sand are washed away, leaving the
gold. This is essentially the same process prospecters used while
panning.
Underground Mining
This is the mining people normally think of, the extraction of minerals
from deep within the earth. The ore is usually discovered by an outcrop
of the ore body on the surface. A horizontal opening known as an adit
provides the easiest approach to an underground mine. A steep inclined
or verticle opening is called a shaft. Hoisting equipment must then be
used to carry men and materials to and from the mine. At the end of the
shaft is a sump to collect the water that seeps into the mine, a
constant problem.
Passages and cavities cut into the mine are called workings these
workings are supported by timbers, concrete walls and roof bolts to
prevent cave ins. The main workings are:
Levels: These are the main horizontal passageways that extend from the shaft. They are numbered from the surface down.
Drifts: horizontal passages that run from the Levels at right angles and run parallel to the course or drift of a vein.
Crosscuts: horizontal passages dug across the course of the vein.
Raises and Winzes: Verticle openings in Level, Drift or
Crosscut. Raises go upward, Winzes downward. A veritcle passageway
between two levels is also called a Raise from the lower level and a
Winze from the upper level.
Stopes: cavities in whish ore is being extracted or has been extracted during the exploitation phase of mining.
Glory Hole Mining
Glory Hole Mining resembles both surface and underground mining.
Basically a Glory Hole is a Open Pit with steep sides and the ore as
its stripped falls to the bottom of the pit where it is carried out
through an underground tunnel. Glory Holes are used to deepen Open
Pits, to get minerals normal Open Pits can not or sometimes between
level in an underground mine.
Mining is a highly dangerous occupation. Falling rock or roof collapse
cuases many deaths in mines. Miners are also killed by falling or
machinery and blasting accidents. Inhaling rock dust over time can
cause a disease known as Silicosis or Black Lung Disease. Poisonous
gases, fires, dust explosions, and flooding are also serious problems
in mines.