Shaft mining or
Shaft sinking refers to the method of excavating a vertical or near-vertical tunnel from the top down, where there is initially no access to the bottom.
When the top of the excavation is the ground surface, it is referred to as a shaft, when the top of the excavation is underground, it is called a
winzeA winze is an opening in an underground mine that is sunk downward from inside to connect lower levels. The top of a winze is located underground, in contrast to a shaft where the top of the excavation is located on surface....
.
The mine shaft is used to access to an underground
miningMining is the extraction of valuable minerals or other geological materials from the earth, usually from an ore body, vein or seam. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock salt and potash...
facility.
Shaft mining or
Shaft sinking refers to the method of excavating a vertical or near-vertical tunnel from the top down, where there is initially no access to the bottom.
When the top of the excavation is the ground surface, it is referred to as a shaft, when the top of the excavation is underground, it is called a
winzeA winze is an opening in an underground mine that is sunk downward from inside to connect lower levels. The top of a winze is located underground, in contrast to a shaft where the top of the excavation is located on surface....
.
Off-shaft access
The mine shaft is used to access to an underground
miningMining is the extraction of valuable minerals or other geological materials from the earth, usually from an ore body, vein or seam. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock salt and potash...
facility. Horizontal workings off the shaft are called drifts, galleries or levels. These extend from the central shaft towards the ore body. The point of contact between these levels and the shaft itself is known as the inset, shaft station or plat.
Surface facilities
On the surface above the shaft stands a building known as the
headframeA Headframe or Gallows Frame or Winding Tower is the structural frame above an underground mine shaft. Modern headframes are built out of steel, concrete or a combination of both. Timber headframes are no longer used in industrialized countries, but are still used in developing nations...
(or winding tower, poppet head or pit head). Depending on the type of
hoistIn underground mining a hoist or winder is used to raise and lower conveyances within the mine shaft. All hoists are powered using electric motors, historically with direct current drives utilizing solid-state converters , however modern large hoists utilize alternating current drives that are...
used the top of the headframe will either house a hoist motor or a
sheave* Sheave , the wheel of a pulley* Sceafa, a legendary Lombardic king* Sheaves...
wheel (with the hoist motor mounted on the ground).
The headframe will also contain bins for storing ore being transferred to the processing facility. If the shaft is used for mine ventilaton a plenum or casing, is incorporated into the headframe to ensure the proper flow of air into and out of the mine.
Shaft lining
In North and South America, smaller shafts are designed to be rectangular with timber supports. Larger shafts are round and are concrete lined.
Shaft compartments
A mine shaft is frequently split into multiple compartments. The largest compartment is typically used for the cage, a conveyance used for moving workers and supplies below the surface. It functions in a similar manner to an
elevatorAn elevator or lift is a vertical transport vehicle that efficiently moves people or goods between floors of a building...
. The second compartment is used for one or more
skipsA rubbish skip is a large open-topped container designed for loading onto a special type of lorry...
, used to hoist
oreAn ore is a type of rock that contains minerals such as gemstones or metals that can be extracted through mining and refined for use. Samples of ore in the form of exceptionally beautiful crystals, exotic layering visible when sectioned or polished or metallic presentations such as large nuggets or...
to the surface. Smaller mining operations use a skip mounted underneath the cage, rather than a separate device, while some large mines have separate shafts for the cage and skips. The third compartment is used for an emergency exit; it may house an auxiliary cage or a system of
ladderA ladder is a vertical or inclined set of rungs or steps. There are two types: rigid ladders that can be leaned against a vertical surface such as a wall, and rope ladders that are hung from the top. The vertical members of a rigid ladder are called stringers or stiles...
s. An additional compartment houses mine services such as
high voltage cablesThe term high voltage characterizes electrical circuits, in which the voltage used is the cause of particular safety concerns and insulation requirements...
and pipes for transfer of
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
,
compressed airPneumatics is the use of pressurized gas to effect mechanical motion.Pneumatics is that branch of technology,which deals with the study and application of use of pressurised gas to affect mechanical motion....
or diesel fuel.
A second reason to divide the shaft is for
ventilationUnderground mine ventilation provides a flow of air to the underground workings of a mine of sufficient volume to dilute and remove noxious gases . The source of these gases are equipment that runs on diesel engines, blasting with explosives, and the orebody itself...
. One or more of the compartments discussed above may be used for air intake, while others may be used for exhaust.
See also
- Underground mining (hard rock)
- Drift mining
Drift mining is a method of accessing valuable geological material, such as coal, by cutting into the side of the earth, rather than tunneling straight downwards . Drift mines have horizontal entries, called adits, into the mineral deposit from a hillside. Drift mines are distinct from slope mines,...
- Raise borer
A raise borer is a machine used in underground mining for excavate a circular hole between two levels of a mine without the use of explosives.The raise borer is set up on the upper level of the two levels to be connected on an evenly laid platform, typically a concrete pad...
- Salt-concrete
Salt-concrete is a construction material that is used to reduce the water inflow in mining shafts in salt mines. It is composed of 16 % cement, 39 % halite ,16 % limestone powder, 14 % water and 15 % sand.-History:...
- Headframe
A Headframe or Gallows Frame or Winding Tower is the structural frame above an underground mine shaft. Modern headframes are built out of steel, concrete or a combination of both. Timber headframes are no longer used in industrialized countries, but are still used in developing nations...
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