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Abutment Pressures
When an opening is created in a coal seam, the stress that was present before the opening was created is re-distributed to the adjacent coal pillars that are left. The areas within the remaining coal where the vertical stress is greater than the average are called abutments and hence the stresses in those areas are called abutment pressures.

An access tunnel from the surface to the mine workings that is nearly horizontal. Adits are used to access longwall mines from previously worked highwall mines.

Air Split
A division of airflow into two or more separate air ways.

Air Way
Underground passageway along which air passes.

An instrument for measuring the velocity of air within a mine passage.

Coal of the highest rank having a high carbon content and a low volatile matter. It has a bright black lustre.

A upward(convex) folding of the rock strata.

A bed of rock strata that contains water. The presence of aquifers must be taken into consideration when designing any mine.

A steel support of two or three sections which, when bolted together, form a strong permanent support.

Armoured Face Conveyor (AFC)
An articulated chain conveyor that transports the coal along the longwall face after it has been cut by the coal shearer. From the AFC, the coal is transferred to the beam stage loader.

Auxiliary Fan
Used in conjunction with air ducting to direct portion of the main ventilating current to the working face.

The roof of any mine opening.

Barrier Pillar
A section of coal that is left to substantially separate two working panels. This technique is often used for mines that are susceptible to spontaneous combustion. If a spontaneous heating occurs in one panel the barrier pillar will prevent the coal in the adjacent panel becoming kindred. They are also used to reduce the amount of subsidence that can occur at the surface. This technique can also be used to prevent accidents such as inrushes of water, gas or explosions.

Stratum of coal or other sedimentary deposits.

Belt Extension
A job of adding lengths of structure to a conveyor belt to move its termination point inbye.

Belt Idler
A cylindrical roller which is mounted on a frame and supports and guides a conveyor belt.

Belt take-up
A pulley mechanism that is attached under tension to the drive head of the conveyor belt. It is used to maintain tension in the belt conveyor for optimum performance.

A person who operates and maintains the belt.

Belt Retraction
A job of removing lengths of structure from a conveyor belt to move its termination point outbye.

The treatment of mined material to make it more concentrated and suitable for sale to the customer.

Bituminous Coal
A general term descriptive of coal intermediate in rank between sub-bituminuos and semi-anthracite and including coking coals. Bituminous coals may be either bright or dull and a re usually banded in appearance.

Black Coal
A general term for coal of either sub-bituminous, bituminous or anthracite rank.

Black Damp
This concept is a term generally applied to carbon dioxide rapidly changing and can no longer be regarded as correct. It is also applied to an atmosphere depleted by oxygen, rather than having an excess of carbon dioxide.

Bolt Torque
The torque applied to a roof bolt when it is being installed to achieve a required tension.

Booster Fan
An appliance used in ventilation district return airway to increase air flow within that district.

This is an anti-static woven material used in ventilation to direct the flow of air.

Circuit breaker in electrical circuits.

Brown Coal
Coal of the lowest rank, of a soft friable nature and high moisture in the air-dried sample.

Box-like container attached to a winding rope and used to hold the skips or the men during the hoisting operation in the shaft.

Caking Coal
Coal which leaves a coherent (agglomerated) residue when subjected to fact heating.

Cap Lamp
A rechargeable, battery operated, light worn on a miner’s safety helmet.

Car Cable
The electric trailing cable on a shuttle car.

Caterpillar is a manufacturer of longwall mining equipment. You can visit their web-site at

Chain Conveyor
A conveyor on which material is transported along solid pans by the scraping action of crossbars that are connected by chains. AFC’s and beam stage loaders are two examples of chain conveyors that are used in longwall mining.

Chain Pillar
The pillars that are left to along the entry roads to a working panel in order to support the roof.

Check Inspector
Official of the union appointed by the underground employees to look after interests regarding safety. The duties are laid down in the regulations governing mining operations.

A roof support unit for use in large openings which consists of wooden or steel blocks stacked between the floor and the roof often filled with stone for added stability.

Cinder Coal
(Natural coke, cinder). Coal which has been significantly altered by heat associated with natural igneous activity; usually local in character.

Parallel cleavage planes or partings crossing the bedding and along which the coal breaks more easily than in any other direction.

Coal Mines Regulation Act (CMRA)
The Coal Mines Regulation Act (CMRA) is the Act that all coal mines in NSW must operate within. The Act can be viewed on the NSW NSW Resources & Energy website

Coal Washing
A beneficiation process to separate the coal from unwanted rock material by utilizing the differences in their specific gravities. The unwanted material is generally heavier than coal and sinks in water where as coal is lighter and floats in water.

Coking Coal
Coal that is used to produce coke. Coke is used in the process to produce steel products.

Continuous Miner
An electric powered cutting machine used to remove coal from the face and load it into the shuttle car.

The means of transporting coal from the coal panels to the underground storage bin. It consists of an endless belt driven by a motor drum system over a structure roller assembly. They are popular choice for most mines because of their ability to handle production surges high tonnage rates that are achieved from longwall mines.

Upward movement of a relatively soft floor of a seam under pressure from adjacent coal. Sometimes used for widespread movement of the upper strata because pillars left for roof support were insufficient size over a relative large area.

Lunch or lunch-time.

A machine that is used for crushing coal and other materials in order to reduce their particle size.

Cut Through
This is the roadway that joins one to another; they are numbered in sequence going inbye along the length of the development.

Supervisor in charge of a section or district of a mine, and all employees working therein. The statutory duties, responsibility and authority of a deputy are set down in the regulations governing mining.

Development Mining
Work that is undertaken to expand the mine reserves rather than work that is involved in the extraction of coal.An example of development work is the driving of roadways that will form a new longwall panel.

Dezega Pacific
Owned by Donetsk Mine Rescue Equipment Company (DZGA) is a worldwide leading manufacturer of respiratory equipment based in Donetsk, Ukraine.

Having more than 60 years of successful experience in safety business the company produces high quality self-rescuers for mining and other industries as well as breathing apparatus for mine rescue and firefighting operations.

The company is responcible for designing, producing, distributing and servicing their products with the only goal to protect users in the situations when nothing else can help them to survive. Their chief priority is ensuring the excellent quality of products. DZGA continuously improves its products, considering their performance should exceed the requirements of any standard.

They were among the first 3 companies in Ukraine which were certified according to ISO 9001:2000.

Since 1950 DZGA has produced more than 6 million oxygen self-rescuers and hundred thousand rebreathers which is their main reference. Their safety products are distributed all over the world and are thankful to their local and foreign customers for their confidence in their products and the brand.

The angle of a coal seam relative to the horizontal. It is usually expressed as (1 in X) in a certain direction.

Night Shift, from about 11 PM till 7 am, depending on individual mine sites.

Downcast Shaft
Shaft or other mine opening which carries fresh air form the surface down to the mine workings.

An inclined access from the surface to the coal seam or from coal seam to coal seam. It often contains a conveyor belt or man riding train.

The driving mechanism of motor, gearbox and drive drum which is responsible for the movement of the conveyor belt.

Discharge point for loaded shuttle cars and other haulage devices.

An intrusive igneous body which has disrupted the coal seam by cutting through it. Usually it has a sintered band of coal each side of the rock.

They are a mining equipment manufacturer specializing in longwall shearers and chainless haulage system for AFC’s. The company is based in Germany and also has operations in America, Great Britain, Poland and South Africa.You can visit there website at .

An underground passage used for haulage, ventilation, or as a manway.

Face Cleat
The principal cleavage plane that is perpendicular to stratification of the coal seam.

Factor of Safety
The ratio of the strength of a coal pillar against the amount of load being applied to it by the overlying strata. The factor of safety is used in determining the acceptable size of coal pillars that are let when entry tunnels are being driven.

Break in the continuity of a coal seam or rock strata. There are many types of faults.

A machine that moves coal onto a conveyor belt, an example being a beam stage loader.

Any mixture of methane and air is firedamp. If the methane content in air is between 5% and 14% the mixture will explode and this has been the source of many explosions in coal mines. If above 15% the mixture will burn and hence the name firedamp.

Flameproof Equipment
Equipment within which an explosive mixture of gas can ignite without igniting the explosive gases surrounding the outside of the equipment.

The scraping bars that transport material on chain conveyor.

Floor Heave
The process of the floor of a mine beginning to lift as a result of high ground stresses.

Gas Drainage
The system used to extract gas from the coal and remove it from the mine. Some mines utilize the gas to operate gas powered turbine to generate electricity.

Gate end box
An electrical control centre used in a panel to control and distribute power to face machinery.

Gate Roadway
A roadway that provides access to a working panel.

The area abandoned and left to collapse after the extraction of coal.

Same as goaf. This term is usually used in America.

Ground Control
A collective term given to the techniques that are used to prevent the collapse and failure of mine openings.

The transportation of men, materials or ore from one point to another generally in a near horizontally direction. Vertical transportation is generally called hoisting.

Immediate Roof
The roof strata that is immediately above the coal seam. This is the strata the requires support for the mine openings to remain competent.

In Situ
In the natural or original position with references to rock strata.

The direction along a roadway towards the face thus going away from the surface entry.

Person appointed by the Government (Department of Mines) under the mining regulations. His/Her duties include the making of examinations of the mine to ascertain whether the regulations relating to the operations are being observed.

Any roadway that is taking fresh air into the workings.

A discontinuity in the rock strata where there is no sign of relative movement.

Joy Global
A manufacturer and supplier of mining equipment. Joy can supply all the components for a longwall mining installation. Joy’s international headquarters are in Pennsylvania, America. Their Australian headquarters are in Moss Vale NSW. They also have operations in China, Mexico, Poland, Russia, South Africa and United Kingdom. You can visit their website at

A brownish-black coal composed of vegetable matter which has been altered more than in peat, but less than in sub-bituminous coal.

A system of working coal in which the seam is extracted on a long face.

Main Entry
A main access roadway to the working panels

One man working one shift comprises a man shift. Output of coal in tonnes per man-shift is accepted as a measure of the efficiency of the operation.

A potentially explosive, lighter than air, gas which comes out of coal seams.

Methane Monitor
An instrument that is used to measure the amount of methane present in the mine atmosphere. It is often mounted on mining machinery or can be used in a hand held form by shift supervisors to take measurements in non-working areas.

Mitsui Miiki
They are a shearer manufacturer that is based in Japan. Most of their web-site is in Japanese but some of it is in English. It is also a useful resource to gain an insight into coal mining in Japan. You can visit their web-site at

Natural Ventilation
Ventilation that is provided without the assistance of fans or furnaces. The occurrence of natural ventilation pressures must be considered when designing a mine ventilation system.

A violent displacement of fine coal at the face caused by excessive gas and earth pressure, often associated with areas of weakens in the coal.

The direction along a roadway away from the working face.

Coal that appears at or near the surface.

The layers of material, rock and soil, that overly a coal seam.

An airway built over the top, and a t angle to, another airway. This is necessary to separate intake and return airways in certain locations.

A mine is broken up into a number of panels which are working places for each mining crew.

A block of coal left to hold up the roof and formed by driving a connected series of headings and cut-throughs.

A chronic disease of the lungs that is caused by inhaling coal dust.

An entrance to a tunnel.

Preparation Plant
The place a the surface of the mine where coal is cleaned and prepared for sale to the customer(s).

Primary Roof
The main roof above the secondary roof.

A timber prop roof support set tightly between the roof and the floor.

A constructed stopping which controls the air flow in a roadway by means of varying the size of of an opening built into the stopping to suit requirements.

A chemical material that is inserted into the top of a drill hole when a roof bolt is being installed. The resin acts a glue to hold the bolt securely in the drill hole.

Respirable Dust
Coal dust particles that are 5 microns or less in size.

Return (Airway)
Opening along which air returns from the working face(s).

Return Air
Air or ventilation that has passed through the workings. In general, it will contain relatively high concentrations of gas and dust.

Heading used for movement of the air form the face and out of the mine.

The name given to the coal walls of the roadway. These are the sides of the pillars.

The immediate strata above a working place or underground roadway.

Roof Bolt
A length of steel rod used as a roof support by securing it in a hole drilled into the roof. It binds the roof strata together to prevent them from collapsing into the roadway.

Roof Jack
A steel hydraulic jack that is used as a temporary roof support.

Roof Support
Any material that is used to support the overlying roof strata. Examples of roof supports are roof bolts, cable bolts, arches, powered supports, timber chocks or hydraulic roof jacks.

Second Means of Egress
The alternative roadways from the working area of the mine which can be used in an emergency.

Self-Contained Breathing Apparatus
A self-contained supply of oxygen used during rescue work from coal mine fires and explosions. Sometimes called self-contained self rescuer (SCSR).

Worn by miners and used in the event of a suspected explosion Used to remove lethal quantities of carbon monoxide (and other poisonous gases) from the breathed air.

An opening,usually vertical, connecting the surface with the underground workings.

Shuttle Car
An electrically driven machine that is used to transfer the coal from the continuous miner to the start of a conveyor belt.

The crumbling and falling away of material from the longwall face.

Crushed limestone (calcium carbonate) added to coal dust to reduce its potential to explode.

Stone Dusting
Operation of spraying finely ground limestone or other non-combustible and non-siliceous dust on to coal. The limestone particles mix with the coal dust and reduce the possibility of a coal dust explosion.

A brick or plaster wall in a cut-through which is used to direct the air flow.

Sub-Bituminous Coal
Coal of a rank between lignite and bituminous.

The gradual sinking, or sometimes the abrupt collapse, of the rock and soil layers into an underground mine. Structures and surface features above the subsidence zone can be affected.

An auxilliary entry gateroad of a longwall panel.

Trailing Cable
Heavily insulated electrical cable used to bring power to an electrically operated machine, such as a shuttle car. The cable trials along the ground from a plug-in power point to the machine.

Transfer Point
A point in the transportation system where material is transferred between two conveyances, i.e. from one belt conveyor to another.

Under – Manager
A position holding responsibilities defined by law. An undermanager is usually the person in charge of underground mining operations on a shift and is next in authority under a manager or deputy manager. Requiring a 2nd class certificate of competency or certificate of service.

Upcast Shaft
Shaft or other mine opening through which air returns to the surface after ventilating the mine workings.

The supply of fresh air to all parts of the mine workings and the removal of return air from the mine.

Volatile Matter
The part of coal that gives it it’s ability to burn as they contain mostly hydrocarbons

The depth of coal that is cut by a shearer drum from the longwall face on each traverse.

“W” Strap
A flat steel plate used as a cross roof support and is held in position by roof bolts.

White Damp
Carbon monoxide gas mixed with air