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    Dictionary of Quarrying Terms

    AAV: abbr. see aggregate abrasion value.

    ac: abbr. see alternating current.

    ACOP: abbr. see approved code of practice.

    ACV: abbr. see aggregate crushing value.

    AIV: abbr. see aggregate impact value.

    AN/FO: see ANFO.

    APS: abbr. see Assisted Private Study Course in Quarrying.

    ASR: abbr. see alkali-silica reaction.

    Abney Level

    Abney level: A small surveying instrument used either as a hand level or for the measurement of vertical angles.

    absolute pressure: Pressure which is measured from the absolute zero of pressure, ie the sum of gauge pressure and atmospheric pressure.

    absolute volume method: A means of calculating the yield of concrete on the basis that the volume of compacted concrete equals the sum of the absolute volumes of the aggregates, cement and water.

    acceleration: The rate of change of the velocity of a point with respect to time. If no change of direction is involved linear acceleration units are m/s2. See also angular acceleration.

    acceleration due to gravity: Acceleration with which a body would fall freely under the action of gravity in a vacuum. This varies according to the distance from the centre of the earth but the accepted value is 9.81 metres per second. Note: Variations from the accepted value may occur where, for instance, there are massive ore bodies close to the surface and these anomolies are employed in mineral exploration. Symbol: g.

    accelerator: In concrete technology, an admixture which speeds up the hydration process to produce a high early compressive strength.

    accumulator: 1 A voltaic cell which can be charged and discharged, a portable store of electric power usually called a battery. 2 see hydraulic accumulators.

    action level: The Noise at Work Regulations 2005 define several action levels corresponding to particular exposure levels: notably 80 and 87dB(A) and a peak level of 135dB(C).

    activators: 1 Added active items which enable an otherwise inert material to demonstrate improved properties, eg cement with ground granulated blast-furnace slag. 2 see regulators.

    active component: The component of the phasor current or voltage which is in phase with the voltage or current respectively.

    active power: The product of the active component of the current and the voltage, or of the active component of the voltage and the current. Units: watts.

    active tip: A term no longer in use to describe a tip on quarry premises which is in use and covered by the now revoked Mines and Quarries (Tips) Regulations 1971.

    actual power: see active power.

    actuator: A machine using a form of energy (electrical, hydraulic, pneumatic) to move a load or apply a force.

    adiabatic: A process during which no heat transfer takes place.

    admixture: A material, usually a liquid, which is added to a batch of concrete during mixing in order to modify the properties of the fresh or hardened concrete. There are many types of admixtures for concrete including: accelerators, retarders, plasticizers, air-entrainers etc. see British Standard 5075, Parts 1,2 and 3.

    advance reduction: The process of overburden removal ahead of the coaling operation on an open cast coal site.

    aeolian: Wind-borne materials.

    aerated concrete: Concrete made by adding constituents to the mix, usually powdered aluminium, which, by chemical reaction, cause gas bubbles to form within the concrete. This reduces the density and increases the insulation value of the concrete.

    aerial surveying: see photogrammetry.

    aggregate: Particles of rock or inorganic manufactured material which when brought together in a bound or unbound condition form part or whole of a building or civil engineering structure.

    aggregate abrasion value: A BS test retained after adoption of EN standards. A measure of the resistance of an aggregate to abrasion as determined by the abrasion test defined in BS 812. abbr. AAV.

    aggregate crushing value: An obsolete measure of the resistance of an aggregate to crushing determined by the compression test as defined in BS 812. abbr. ACV. Largely replaced first by the Ten Percent Fines test and then by the Los Angeles test following harmonization of European standards.

    aggregate impact value: An obsolete relative measure of the of the resistance of an aggregate to sudden shock as determined by the impact test defined in BS 812. abbr. AIV.

    agitator: A rotatable truck-mounted container used for keeping plant-mixed concrete in a fresh state.

    air classification: The process of sizing of particles in a current of air.

    air compressor: A machine, driven by a motor, for compressing air for power purposes, eg rock drilling.

    air entrainment: The deliberate incorporation of air into a concrete mix, usually by admixture. See aerated concrete.

    air overpressure: The pressure in excess of ambient atmospheric pressure which occurs when an air blast wave passes a given position. The maximum excess pressure is known as the peak overpressure and it is when this is excessive (>180dB) that structural damage may occur.

    air-flush: Term applied to drilling using compressed air to clear the chippings and to cool the bit.

    air-line lubricator: An oil reservoir connected into the compressed-air supply line 2m or 3m from the drill or air motor to which it feeds lubricating oil in the form of an atomized spray.

    airblast: An airborne shock wave resulting from the detonation of explosives. May be caused by burden movement or the release of expanding gas into the air. Airblast may or may not be audible.

    airblaster: Pervious ceramic pads introduced into the base cone of a hopper so that compressed air can be introduced to assist the flow of difficult powders.

    airleg: A device incorporating a pneumatic cylinder, providing support and thrust for a jackhammer.

    airlift pump: A pump for the raising of water from a well or sump by the injection of compressed air into the bottom of a pipe which has been submerged to a considerable depth in the water. The compressed air expands and rises, and, as the overall density of water and air bubbles is lower than that of the water, it is forced to the surface by the higher pressure of the water outside the pipe.

    alidade: 1 The rotatable part of a theodolite. 2 An instrument used in plane-tabling.

    alkali-silica reaction: A process of deterioration in concrete resulting from the reaction between alkalis, principally from the cement, and certain types of aggregate. abbr. ASR.

    all-in aggregate: A mixture of coarse and fine aggregate.

    alligator fastener: A type of fastener used to join the ends of conveyor belts. It consists of a pair of steel strips, each incorporating a series of teeth along both edges which are hammered through the belt and their ends bent over; the ends of the belts are connected by a hinge pin.

    alloy steels: Steels to which have been added elements not present in plain carbon steels to impart to them certain special properties.

    alluvium: A collective term for unconsolidated detritus such as clay, silt, sand and gravel deposited by streams and rivers as sorted or semi-sorted sediment in channels and over flood plains and deltas.

    alternating current: A current varying with time in a cyclic manner, the current direction reversing periodically.

    alternator: A machine used to generate alternating current.

    aluminium: A metal commonly used as a fuel or sensitizer in explosives and blasting agents, normally used in finely divided particle or flake form. It is also used, in a powdered form, as a foaming agent in the production of lightweight bricks and blocks.

    ammeter: An instrument for measuring current. It is connected either in series with the circuit carrying the current or, where heavy currents have to be measured, to the secondary winding of a current transformer the primary of which carries the current to be measured.

    ammonium nitrate (NH4NO3): The most commonly used oxidizer in explosives and blasting agents.

    amortization: Depreciation of assets over a fixed life.

    ampere: The SI unit of electric current. Symbol: A.

    ampere-hour: A unit of electric charge. It is the quantity of electric charge which passes in one hour at a current of one ampere. Symbol: Ah.

    amplitude: The maximum displacement from the mean position in an oscillating motion, ie the height of the wave measured from the axis. Note: In the case of a screen with a straight-line motion or elliptical motion, it is half the total movement or half the major axis of the ellipse. In the case of a circular motion, it is the radius of the circle.

    anchor bolt: see foundation bolt.

    anchor dredger: a marine aggregate recovery vessel which dredges from one point on the sea-bed. See trailer dredger.

    ANFO: A mixture of ammonium nitrate and fuel oil in such proportions that the mixture can be detonated with a suitable initiator.

    ANFO mixer

    ANFO mixer: A trailer- or truck-mounted machine for on-site mixing of ammonium nitrate and fuel oil and charging the blasthole.

    angle of friction: The angle between the normal to two contacting surfaces and the direction of the resultant reaction between them, when a force is just tending to cause sliding.

    angle of nip: Angle between the faces of a crusher.

    angle of repose: The maximum angle between the surface of a heap of loosely piled material and the horizontal.

    angledozer: A bulldozer with the blade set at an angle so that it pushes material forward and to the side.

    angular acceleration: The rate of change of angular velocity. Units: rad/s2.

    angular velocity: The rate of change of angular displacement. Units: rad/s.

    angularity number: An indication of aggregate shape which relates the voids ******* of a compacted sample to that of a rounded gravel sample.

    annealing: A process which removes stresses set up during the manufacture of a structure of steel and restores it to its normal condition, at the same time softening it and refining the grain structure. It involves heating the metal to a selected temperature, holding at this temperature for some time and cooling at a slow, controlled rate. Annealing is also applied to copper and other metals, as well as glass.

    anode: The electrode from which an electric current flows.


    anticline: An arch-like fold in stratified rocks.

    aperture size: The dimension or dimensions defining the opening in the screen deck, usually with a qualification as to the shape of the aperture, eg round hole, square mesh, long slot.

    apparent dip: The dip in any random vertical section, having a value between zero in the section containing the line of strike and full dip at right-angles to that line.

    apparent power: In an ac circuit, the product of the r.m.s. values of the voltage and current. Units: voltamperes (VA).

    appoint: legally, to appoint a person to a position in writing.

    approved code of practice: A publication giving guidance on the implementation of requirements laid down in Regulations made under the Health and Safety at Work Act.

    apron feeder: A device, consisting of a series of steel flights (pans) bolted to heavy-duty chains which run on sprockets, used to draw material at a regulated rate from a stockpile, storage bin or feed hopper. The rate of flow is controlled by varying either the speed of the apron or the depth of material on it.

    aquifer: A permeable water-bearing stratum which is capable of storing and yielding water when tapped by a well.

    arc welding: Welding in which the heat necessary to melt both the plate and filler material is supplied by an electric arc.

    are: The metric unit of area equal to 100m2. A hectare is 100 ares.

    arenaceous: Sandy.

    argillaceous: Clayey or silty.

    armature: 1 The part of a machine in which electromotive forces are induced. 2 The movable part of an electromagnetic circuit which, by attraction, can do useful mechanical work, as in a relay. 3 A piece of ferromagnetic material placed across the ends of a permanent magnet to complete the magnetic circuit.

    armour-stone: Large irregular lumps of hard rock used for sea defences etc.

    armouring: The steel wires or tapes incorporated in an electric cable to provide mechanical protection for the conductors and insulation and to provide a low-resistance earth path between the two ends of the cable.

    artesian well: A well sunk into a permeable stratum which has impervious strata above and below it and from which water flows without pumping.

    articulation: The Articulated dumptruck connection of two parts in such a way as to permit the same relative movement, eg the two sections of the frame joined by two or more pins to form an articulated dumptruck.

    asphalt: A natural or artificial mixture in which bitumen is associated with a substantial proportion of mineral matter.

    asphalt plant: A heating, mixing and storage installation for the production of bitumen-coated aggregate.

    asphaltic cement: Bitumen, a mixture of lake asphalt and bitumen, or lake asphalt and flux oil, or pitch used as a binder.

    asphaltic concrete: A term applied, particularly in the USA, to a rolled asphalt incorporating a continuously graded aggregate.

    assets: Resources owned by a company which have been acquired at a measureable money cost.

    Assisted Private Study Course in Quarrying: The distance learning and tutorial scheme to prepare candidates for the Institute of Quarryings Professional Examination. abbr. APS.

    atomizer: A nozzle through which fuel oil is sprayed into the combustion chamber of an oil engine or burner. Its function is to break up the oil into a fine mist in order to ensure good combustion.

    auger: A tool developed from the Archimedean screw, used for soil sampling or drilling of shallow holes.

    authorized capital: The total amount of capital which the company is allowed to issue as shares of different types, as stated in its Articles of Association and its Memorandum lodged with the Registrar of Companies.

    auto-transformer: A transformer having only one winding per phase; part of the winding is common to both primary and secondary sides. The uses of auto-transformers include the supplying of reduced voltages when starting large induction and synchronous motors.

    auto-transformer starter: A tapped auto-transformer reduces the voltage supplied to a motor during the starting period in order to limit the current taken during that time.

    autoclaving: The curing, in a steam chamber, of freshly cast concrete or sand-lime bricks for up to 24 hours at a steam pressure of about 10 atmospheres, which results in the material acquiring the same strength as would be achieved after a month if air-curing was used.

    autogenous: A term applied to grinding mills which use tumbling action to effect comminution which is achieved by the action of rock or ore particles on one another; no steel balls or rods are used.

    average value: see mean value.

    axial priming: A system of priming for blasting agents in which a core of priming material extends through most or all of the length of the charge.

    azimuth: The horizontal bearing of a line measured clockwise from the meridian from 0 to 360. See whole-circle bearing.

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    BACMI: abbr. British Aggregate Construction Materials Industries. A former trade association for producers of aggregates, ready mixed concrete, lime and coated materials which amalgamated with SAGA to create QPA.

    BCA: abbr. British Cement Association. The trade association for cement manufacturers in the UK.

    Back Acter

    back-acter: A shovel which digs towards the Back acter machine and is capable of digging below track level.

    back breakage: The extent of rock breakage or fracture behind the burden taken in a blast.

    back emf: Voltage induced in a circuit which opposes the applied voltage, eg in the armature of a dc motor as it rotates in its magnetic field.

    backfill: Overburden or inferior mineral which is dumped into a worked out part of an excavation or behind a retaining wall.

    Backhoe Loader

    backhoe loader: Self-propelled wheeled machine with a main structural support designed to carry both a front-mounted bucket loading mechanism and a rear-mounted backhoe. When used in the backhoe mode, the machine normally digs below ground level with the bucket motion towards the machine; the backhoe lifts, swings and discharges the material while the undercarriage is stationary.

    backsight: In surveying, a sight taken towards the previous station.

    bag filter: An apparatus for removing dust from dust-laden air, employing a container made from woven material which permits passage of air but retains solid particles.

    bailer: A tube, fitted with a valve at its base, which is lowered into a borehole to remove cuttings and water.

    balance sheet: A statement showing a companys assets and liabilities at one moment in time, that is the close of business on the date shown. All registered limited companies are, by law, required each calendar year to prepare and publish a balance sheet for the shareholders information and it must be presented in an approved format.

    balanced load: Symmetrical arrangements of loads in an electrical system. Loads are balanced in an ac three-phase system when the loads taken from each phase are equal and at the same power factor.

    ball bearing: A bearing consisting of a number of hardened steel balls which roll between an inner race fitted on to the journal and an outer race held in a housing. The inner and outer races carry shallow spherical tracks on their outer and inner surfaces respectively and a cage between the races keeps the rolling elements separate and evenly spaced.

    ball deck: A coarse mesh secured below the screen surfaces, the area between the two meshes being divided into compartments each of which contains a number of hard rubber balls. With the movement of the screen, the balls bounce freely within their compartments and assist in preventing blinding or pegging of the screen mat.

    ball mill: A grinding machine consisting of a short, horizontal cylinder charged with steel balls which break down the mineral during rotation.

    ballasted tyres: Tyres filled with liquid or dry ballast in order to increase their weight when fitted to the wheels of tractors, graders, wheeled dozers etc. This, it is claimed, results in increased operating efficiency.

    Banana Screen

    banana screen: A multi-slope vibrating screen. The angle of the deck decreases from feed end to discharge end.

    bank of cells: A row of flotation cells in line.

    bar: Unit of pressure equal to 100,000 newtons/m2 or Pascals. Standard atmospheric pressure = 1.0133 bar.

    bar screen: A stationary inclined screen, comprising longitudinal bars, spaced at intervals, on to which the material to be screened is fed at the upper end.

    barrel washer: see washing barrel.

    barytes: Barium sulphate, BaS04. A dense mineral (RD 4.5) used in the manufacture of paint, textiles and drilling mud, and as an aggregate in radiation shielding. Can be an undesirable impurity in limestone.

    basalt: A fine-grained basic igneous rock occurring in dykes, sills and lava-flows; essential minerals are plagioclase felspar and augite. Dark grey to black in colour; relative density 2.8-3.3; aggregate crushing value 7-25.

    base charge: 1 The detonating component in a detonator initiated by the priming charge. 2 The bottom charge in a deep blasthole.

    base line: An accurately measured line which forms one side of the first triangle in a triangulation survey.

    basecourse: 1 The European term for the layer(s) that form the main structural element of the road. 2 An obsolete British term for the European term, binder course, which forms part of the road immediately below the surface course.

    basic work *******: The minimum time, at a standard rate of working, in which a task can be completed if everything is carried out perfectly.

    basin: A rock structure in which the strata dip inwards on all sides.

    batch-heater plant: A heating and mixing plant particularly suited to the production of a range of coated materials.

    batch mixer: A mixer for bituminous or concrete materials which mixes batches of such materials, as opposed to continuous mixers.

    batching plant: A plant containing the equipment to measure, by weight or volume, the quantities of different materials required to make a correct mix of concrete.

    batholith: A large and, originally, deap-seated igneous intrusion. See dyke.

    batter: A constructed, uniform, steep slope. The inclination to the vertical of such a slope is expressed as one unit horizontally to so many units vertically.

    battery: An assembly of similar units.

    Baum jig: A jig used for separating coal from shale in which a pulsating motion is given to the water by intermittent admission of compressed air to the wash-box.

    beam compasses: An instrument used to draw arcs of larger radius than are possible with ordinary compasses. It consists of a beam of metal or wood carrying two adjustable heads which take a point and a pen or pencil.

    bearing: 1 The horizontal angle between a datum direction such as north and a given line. 2 Device provided to support and hold a revolving shaft in the correct position.

    bed: A layer of rock or mineral.

    bedding: A formation of distinct sedimentary rock layers or beds one upon another.

    bedding plane: The interface between two adjacent beds of sedimentary rock.

    bedplate: A cast-iron plate or steel frame on which a machine is mounted; it is usually bolted to the floor.

    bedrock: The solid rock underlying superficial deposits

    behavioural science: A study in man management based on motivation theory.

    belt feeder: A short endless belt conveyor for feeding material, for example, from a bunker.

    bench mark: A point of known elevation above Ordnance datum which has been established by the Ordnance Survey. abbr: BM.

    benches: The long horizontal levels or steps to which successive quarry faces are taken and along which mineral, stone or overburden is worked.

    benching: A method of working opencast pits or quarries in benches usually using rows of blastholes drilled parallel to the face.

    bending moment: At a given section of a beam, the bending moment is equal to the algebraic sum of the moments of all the forces to either side of the section.

    beneficiation: The processing of rocks and minerals to remove unwanted constituents, ie improve their quality.

    berm: An embankment usually constructed from earth or overburden to form a safety barrier.

    Bernoullis law: The total kinetic, potential and pressure energy per unit volume of a fluid passing through a system is constant at all points in that system.

    bevel gear: A system of toothed wheels which connect shafts that are at an angle to each other but in the same plane.

    bimetal: Two or more metals, having different coefficients of expansion, bonded together to form a temperature-sensitive device. A change in the temperature of a bimetallic strip results in a change of curvature and this is utilized in electrical indicating instruments and safety devices.

    binder: 1 Bitumen used to cement aggregate particles or to stick chippings to a road surface. 2 Any cementing agent used for binding soil or aggregate.

    binder course: The European term for the course immediately below the surface course in a flexible road construction.

    biotite: A dark-coloured iron-bearing member of the mica group of rock-forming minerals. It occurs as a constituent of many igneous and metamorphic rocks.

    bit: 1 A cutting tool which is detachable from the drill rod. 2 The end of a drill stem that forms the actual cutting edge.

    bitumen: A viscous liquid or solid consisting of hydrocarbons and their derivatives. It is soluble in carbon disulphide, substantially non-volatile and softens gradually when heated. It is black or brown in colour and has waterproofmg and adhesive properties. It is derived from petroleum or from naturally occurring asphalt.

    bituminous: Containing, or mixtures of, road tar, bitumen or pitch.

    black powder: A low explosive composed of sodium or potassium nitrate, charcoal and sulphur.

    Blake Crusher

    Blake crusher: Double-toggle jaw crusher originally designed in 1858 by E.W. Blake.

    blast: The detonation of explosives to break rock.

    blast area: The area near a blast within the influence of flying rock missiles or concussion.

    blasthole: A hole drilled in rock or other material for the placement of explosives.

    blasting agent: A primer sensitive explosive such as ANFO.

    blasting gelatine: A high explosive; the most powerful commercial explosive, taken as the standard of explosive power.

    blasting ratio: The ratio of the yield of material from a blast to the weight of explosives used; measured in tonnes/kg.

    bleeding: 1 Separation of water from concrete after compaction when there is a tendency for the solids to settle and the displaced water to be pushed to the surface. 2 The occurrence of free bitumen from an over-rich load of coated material in transit or on the road.

    blinding: 1 The blocking of screen apertures by the agglomeration of damp fine material, this results in a reduction of the effective area of the screen. 2 The application of fine material to a surface to reduce the surface voids or to cover a bituminous binder.

    blow-bars: The replaceable hammers rigidly attached to the rotor of an impact crusher.

    blown-out shot: A shot which has expended its force outwards from the line of the shothole without doing any appreciable blasting work.

    bolted-plate fastener: A type of conveyor belt fastener which consists basically of pairs of steel plates which are used to clamp the ends of the belt together. The plates may be in two halves connected by hinge pins.

    Bonds third theory: A comminution theory concerned with the energy required to reduce a given size of feed to a required size of product. On his theory F.C. Bond based an empirical formula which may be used to compare the efficiencies of crushing plants etc.

    boning rod: A T-shaped staff used with other similar staffs to furnish a line of sight whereby, from two given points, other points at the same level or on the same gradient can be established.

    booking: In surveying, the recording of field observations in such a way that they can be understood, often by someone else, when later used in the field or office.

    boom: A cantilever structure: 1 attached to lifting or excavating equipment and at the outer end of which is fixed the pulley over which the hoist rope passes 2 carrying a conveyor used to feed a stockpile.

    booster: A unit of explosive or blasting agent used for perpetuating or intensifying an explosive reaction.

    borehole logging: The determination of physical, electrical and radioactive properties of the rocks traversed by a borehole.

    borrow pit: Excavation adjacent to major works site to provide construction materials.

    boss: A circular form of igneous intrusion; a small-scale batholith.

    bottom initiation: see inverse initiation.

    boulder clay: Glacial clay, generally containing a variety of boulders or pebbles.

    Bows notation: A method of notation for forces acting at a point; the spaces between the forces within the structure are lettered in order, so that each force is identified by means of the two letters in the spaces on either side of it. By this device vector diagrams can be lettered correspondingly.

    Bowl Scraper

    bowl scraper:A load-haul-dump machine in which the bowl is towed behind a tractor unit, fills by a planing action, hauls the spoil to the dump site and empties by means of an internal ejector blade pushing forward. Used in soft ground or in ground that fragments well after ripping or blasting.

    box cut: The initial opening to establish a working face for open-pit mining,

    brass: An alloy of copper and zinc, but small amounts of elements such as aluminium, iron, lead, manganese and nickel are frequently added to give increased strength and other mechanical properties. Brasses can be readily machined.

    break point: 1 The instant at which one element in a work cycle ends and another begins. 2 The point at which a bitumen emulsion moves out of its aqueous phase as part of its setting process. Usually accompanied by a change of colour from brown to black.

    breakout force: The force with which an excavator is capable of pushing its bucket through the rockpile or face.

    breast hole: A horizontal or near-horizontal blasthole used to create or improve a quarry floor.

    breccia: A rock consisting of broken angular unworn fragments held together by a natural cement.

    brick paving: A surface composed of bricks laid in a regular pattern on a prepared roadbase.

    bridge wire: A very fine filament wire embedded in the ignition element of an electric detonator. An electric current passing through the wire causes a sudden temperature rise resulting in the ignition element being ignited.

    British Standard: A numbered publication of the British Standards Institution describing the quality or dimensions of a product, and methods of testing. By their use in specifications architects and engineers can reduce the length of their descriptions to a reference, eg BS 4483 : 1985. Specification for steel fabric for the reinforcement of concrete.

    bronze: True bronzes are alloys of copper and tin, but the name is now applied to other alloys not containing tin, eg aluminium bronze. Various types of bronze are used for springs, bushes, bearings, valve bodies etc.

    brush: A conductor used to make electrical contact between a stationary and a moving surface.

    bucket-chain excavator: A continuous-feed machine designed to give a high output of soft material using a chain of buckets and essentially designed for digging below grade.

    bucket elevator: A continuous line of buckets attached by pins to two endless chains running over tracks and driven by sprockets; alternatively, the buckets are attached to a rubber belt. Used for raising loose materials or slurries at high angles or vertically.

    bucket-wheel excavator: A continuous-feed machine, usually carried on crawler tracks, consisting essentially of a large cutting wheel with buckets mounted on the periphery.

    bucket-ladder dredge: A dredge having buckets moving in a continuous chain, reaching down into the deposit to be dredged, and lifting it for discharge into the vessel.

    budgetary control: A costing and cost-control technique by which the management of a company, having set out to anticipate their volume of trading and consequent production costs for a given period in the future, compares actual performance with budget.

    buffer blasting: Face blasting, either against a high unexcavated rock pile, or using an increased burden (usually 1.5 times or twice the normal burden).

    bulk density: The density of a material including any voids and water contained in it.

    bulk mix: A mass of explosive material prepared for use without packaging.

    bulk strength: The strength of explosive per unit of volume expressed as a percentage of the value of blasting gelatine or ANFO as standard.

    bulldog clip: A V-bolt specially designed to clamp a steel-wire rope doubled back on itself.

    bulldozer: A high-powered caterpillar-mounted tractor fitted with a concave blade mounted in front of the machine. Used for smoothing out irregularities in working areas, levelling the tops of dumps, clearing spillage etc.

    bund: An earth mound or embankment.

    bunker: A storage bin for stone, coal etc.

    burden: The distance between an explosive charge and the nearest free face which is a measure of the work to be done by the charge.

    burner: The heater unit used in coating plants for raising the temperature of aggregate prior to mixing with the bitumen. Fuel may be gas oil, waste oil, gas or coal.

    bursting time: The total time interval between the application of current to an instantaneous detonator and its explosion.

    busbar: An equipotential conductor forming a terminal or junction point in a power system, for the connection of supplies and feeders.

    butt weld: A weld between two pieces of metal without any overlap between them.

    Button bit

    button bit: A percussive drill bit having tungsten carbide inserts the hemispherical ends of which protrude from the face of the bit.

    byte: The unit used in describing the memory capacity of a computer (1 Mbyte = million characters).

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    CAD: abbr. computer-aided design.

    CAM: abbr. computer-aided management.

    CBGM: abbr. cement-bound granular material.

    CCTV: abbr. closed-circuit television.

    CECE: abbr. Committee for European Construction Equipment.

    CEN: abbr. Comite Europeen de Normalisation. The European Community standards organization.

    CENELEC: abbr. Comite Europeen de Normalisation Electrotechnique. The European Community electrical standards body.

    cmr: abbr. see continuous maximum rating.

    COSHH: abbr. Control of Substances Hazardous to Health Regulations.

    CSS: abbr. closed-side setting. See setting.

    cable: A number of insulated conductors protected by armouring and other covering.

    cable ducts: Concrete, earthenware, plastic or steel pipes through which cables are drawn and in which they rest.

    cage motor: see squirrel-cage motor,

    California bearing ratio CBR: A relative value which expresses the bearing capacity of a soil or pavement layer in comparison with a result obtained by using a standard crushed rock material. It is determined by the test procedures defined in BS 1377.

    calcite: Calcium carbonate, CaCO3. Occurs in a variety of crystal forms which are usually white or yellowish in colour. Rhombohedral; relative density 2.7; hardness 3. It is the main constituent of chalk, limestone and marble.

    calendered rubber: Rubber which has been passed through a machine, generally consisting of a number of vertical rollers, in order to ensure uniform thickness.

    calfdozer: A small bulldozer.

    caliper: An instrument used in conjunction with a microlog which, when lowered down a borehole, measures and records the internal diameter throughout its depth.

    calorie: The quantity of heat required to raise the temperature of 1 gramme of water by 1C. This is the unit quantity of heat on the CGS system and is replaced by the joule on the SI system. 1 calorie = 4.186J.

    calorific value: The amount of heat given out when unit mass of a fuel (or unit volume in the case of a gas) is burned completely. In fuels containing hydrogen the value must be related to the temperature at which the measurements are made, because on this depends whether or not the water vapour produced is condensed, giving up latent heat. Units: kJ/kg and kJ/m3.

    calyx drilling: A method of rotary drilling using a toothed cutting bit or chilled shot.

    camber: The convexity given to the curved cross-section of a carriageway etc.

    Cambrian: The earliest period of the Palaeozoic era between about 590 and 505 million years ago, and the corresponding system of rocks.

    candela: The SI unit of luminous intensity which is the quantity that describes the capacity of a source or illuminated surface to emit light in a given direction. Symbol: cd.

    cantilever: A beam which is firmly secured at one end and free at the other.

    cap: see detonator.

    capacitance: The capability of two conductors separated by an insulator to store an electric charge. Symbol: C. Units: farads.

    capacitor: A circuit element which when charged stores electrical energy.

    capital: Money invested in a business by its owners to earn income.

    capped fuse: A detonator fitted with a length of safety fuse.

    carbon monoxide: A highly poisonous, tasteless, odourless gas which is a product of incomplete combustion of inorganic material, eg when an internal combustion engine is idling. It is also created when explosive materials are detonated. Excessive carbon monoxide is caused by an inadequate amount of oxygen in the explosive mixture (excessive fuel). Symbol: CO.

    Carboniferous: The geological period of time 360 to 286 million years ago and the corresponding system of rocks. In Britain Carboniferous rocks are an important source of crushed rock aggregate.

    cardan shaft: A propeller or driving shaft which conveys the power from the gearbox to the differential of a motor vehicle. It is usually connected through universal joints to permit displacement of the rear axle on the suspension.

    Cartesian co-ordinates: Rectangular co-ordinates. See co-ordinates.

    cartridge: An individual unit of explosive, usually wrapped in the form of a cylinder.

    cartridge dust collector: An alternative to a bag filter which uses lower filtration velocities and is more compact.

    case-hardening: Surface hardening of steel by heating in a carbonaceous medium to increase the carbon ******* in the surface layers, then quenching.

    cash flow: The movement of cash into and out of a company.

    casing: Piping used to support the sides of a borehole. Flush-coupled casing is joined with a coupling which has the same outside diameter as the casing, but has two male-threaded ends. Flush-joint casing has a male thread at one end and a female thread at the other; no coupling is used.

    casing drive hammer: A weight used to drive casing down a hole.

    cast iron: An iron-carbon alloy containing more than 1. 7% and usually above 2.5% carbon including substantial amounts of graphite. It is very fluid when molten and is suitable for making intricate castings by pouring into sand moulds. Applications include: cylinder blocks, hydraulic cylinders, crusher frames etc.

    catchment area: The area drained by a stream or river or supplying a reservoir.

    catenary: The curve into which a uniform, inextendable rope falls when suspended from its ends.

    cavitation: The formation of a cavity between the impeller blades of a centrifugal pump and the water normally in contact with it. This leads to the liberation of oxygen and corrosion of metal parts.

    cement: 1 The matrix of a sedimentary rock. 2 The manufactured powder which, through the addition of water, binds together aggregate particles into concrete.

    cement stabilization: The consolidation of a foundation layer through the use of low cement ******* with fill material or subsoil.

    cement-bound macadam: A form of road construction in which a mortar of Portland cement and sand is added to coarse aggregate.

    cementation: The injection of cement grout under pressure into fissured rocks to strengthen and make them impervious to water.

    centi.: A prefix meaning one hundredth.

    centre of gravity: The point in a body at which the entire mass of the body may be regarded as being concentrated.

    centrifugal force: The reaction to a centripetal force, acting radially outwards from the centre of rotation.

    centrifugal pump: A pump with a rotating impeller which imparts an angular acceleration to the liquid, causing it to flow outwards from the centre to the periphery.

    centripetal force: The force which must be applied to a body to cause it to follow a circular path. The centre of the path produced lies in the direction of the applied force, hence the name centripetal or centre-seeking force.

    ceramics: Articles produced by the firing of minerals, especially clay, at very high temperatures.

    chain block: see differential pulley block.

    Chain Curtain Feeder

    chain-curtain feeder: A feeder in which loops of heavy chain suspended from a rotating drum control the rate of flow of material from the chute into the primary crusher.

    chain survey: A linear survey in which no angles are measured, only lengths. .

    chainage: A length measured by means of a chain or steel tape.

    chamber: 1 An excavation to accommodate an explosive charge. 2 The cavity within a crusher in which the rock is subjected to crushing action.

    chambering: see springing.

    charge: The quantity of explosives in a particular shothole.

    check valve: see non-return valve.

    cheek plates: The liners on the two sides of the crushing chamber of a jaw crusher.

    chequered plate: Patterned or perforated metal plate used to make non-slip flooring in mineral preparation plants, power stations etc.

    chilled shot bit:A flat-surfaced bit used with hardened steel shot to drill rock by a milling action.

    china clay: see kaolin.

    chippings: Single-size aggregate nominally between 3mm and 25mm inclusive.

    chisel bit: A percussive drill bit having a single cutting edge.

    choke: see inductor.

    Choke Point

    choke point: That zone of a crushing chamber, usually near the outlet, where the capacity is at a minimum. It is in this zone that choking is most likely to occur.

    choke-fed: The sustained feed to a cone crusher which ensures that the crushing zone remains over-full at all times. This results in a more cubical-shaped product, with the best shape occurring in the aggregate size at the crusher setting.

    choking: A stoppage of the downward flow of rock through a crusher usually caused by the packing of compressed fines near the discharge point.

    churn drill: A cable drill used to drill vertical holes by raising and dropping the heavy drilling tool on the end of a steel wire rope.

    circuit tester: An instrument used to test series circuits in electrical shotfiring for continuity and resistance.

    circuit-breaker: A device for automatically making or breaking an electrical circuit under both normal and abnormal conditions, such as when a short circuit occurs.

    circulating fluid: The fluid, which may be water, mud or air, circulated through the apparatus during drilling. Its chief functions are to remove cuttings, to cool the bit and, in the case of mud, to support the sides of the hole.

    clamping screw: On surveying instruments a screw for clamping a vernier before the tangent screw can be used for fine adjustments.

    clamshell: A twin-jawed bucket used with a crane jib for digging and loading loose material, eg sand and gravel from a flooded deposit.

    clarifier: A thickener used to separate slimes and wash water.

    classification: The separation of particles according to their size, density and shape by control of their settling rate through a fluid medium.

    classified tip: An obsolete term for a tip registered under the Mines and Quarries (Tips) Regulations 1971 because of its hazard potential, see notifiable.


    classifier: A device which separates particles according to their size, shape and density by physical means other than screening.

    clastic: Deposits consisting of broken fragments of earlier rocks.

    clay minerals: Silicate minerals which are mainly formed by the weathering or alteration of feldspars and other primary minerals. Kaolin is one example.

    cleaner cells: Flotation cells used in the retreatment of a rough concentrate to improve its quality.

    cleavage: I In a crystalline mineral, one or more series of parallel planes along which the mineral tends to split. 2 In a rock, definite parallel closely spaced planes along which it may split, and which may be highly inclined to the bedding planes.

    clevis: A V-shaped metal bar drilled in a number of places. One of its uses is to hold the shank of a ripper in any of several positions so that depth and tooth angle may be adjusted to meet prevailing conditions.

    clinker: I The fused product from a cement-making kiln which is subsequently ground into powder. 2 Sintered or fused furnace ash which may be used for hard core or aggregate for concrete blocks.

    clinometer: An instrument used to determine the amount and direction of deviation of a blasthole from the vertical or a hand-held instrument for the measurement of angles of slope.

    Closed Circuit Television Camera

    closed circuit: I An electrical circuit that provides an uninterrupted path for the current. 2 A system in which the product from a crusher passes to a screen, the overflow from which is returned to the crusher for further treatment and the underflow released from the closed circuit.

    closed traverse: A traverse which begins and ends at the same point; its accuracy can therefore be checked.

    closing error: In a closed traverse, the discrepancy between the starting point and the finishing point as calculated from the measurements taken. The error, if small enough, may be distributed throughout the series of measurements.

    coal preparation: Collectively, physical and mechanical processes applied to coal to make it suitable for a particular use.

    coarse aggregate: Graded stone or gravel over 4mm in size for use in concrete or 2mm for coated material.

    coated chippings: Aggregate chippings which have been coated thinly with bituminous material for scattering over a wearing course or for use as a surface dressing. Where bitumen is added just sufficiently to present a prepared surface for added bitumen, the term lightly coated chippings is used.

    coated grit: Grit which has been coated thinly with tar or bitumen binder of such proportions and of such properties as to allow it to be scattered for blinding a wearing course.

    coated macadam: A road material consisting of graded aggregate that has been coated with tar or bitumen, or a mixture of the two, and in which the interlocking of the aggregate particles is a major factor in the strength of the roadbase or surfacing.

    coating plant: A general term used to cover any installation which produces coated material either as a macadam or an asphalt.

    coefficient of friction: The ratio of the limiting friction to the normal reaction between the two surfaces.

    coincidence bubble: An arrangement fitted to precise levelling instruments which enables the surveyor to sight half of each end of the bubble at the same time, with the images of the two halves side by side.

    cold asphalt: Historically, a term used for warm laid, fine bitumen macadam (ie neither cold nor asphalt). It does not occur within current British Standards.

    cold feed: A system of storage hoppers used to supply aggregate to a coating plant.

    Cold Planer

    cold planer: A machine fitted with milling cutters for smoothing, or milling out a road surface up to 150mm in depth, without it first being softened by the application of heat.

    collaring: The operation of starting to drill a hole.

    collector ring: The conductor ring through which the power is transferred from the carriage or tub of an electrically operated shovel or dragline to the rotating body of the machine.

    collectors: 1 A type of flotation reagent. They are organic compounds which render selected minerals water-repellent by absorption of molecules on the mineral surface, thus enabling mineral particles to attach themselves to air bubbles on contact. 2 A means of making an electrical connection between the moving parts of a machine and the supply, eg collector rings on an excavator.

    collimation line: The line of sight of a surveying instrument.

    collimation method: In levelling, a method of calculating reduced levels by subtracting staff readings from the level of the line of sight (collimation line) of the instrument. This method is usually favoured where it is required to obtain the levels of many points from one set-up.

    column charge: A continuous charge in a quarry blasthole.

    Column Charge

    comminution: Size reduction of rocks and ores by crushing and grinding using compressive, impact and abrasive forces.

    commutation: The action of transferring current between the armature conductors, through the commutator segments and brushes, and the external circuit of an electrical machine.

    compacting factor test: Test for the workability of freshly mixed concrete by weighing the concrete which will fill a container of standard size, firstly when allowed to fall in under standard conditions and then when filled and compacted a layer at a time. The compacting factor is the ratio of the partially compacted weight to the fully compacted weight; a higher value indicates greater workability.

    compaction: The process of packing soil or aggregate particles more closely together, to increase the density.

    compactor: see roller and compactor,

    compound-wound motor: A dc motor having field windings connected in both parallel and series with the armature, If the polarity of the series winding is such as to assist the main poles, the motor is cumulatively compound-wound and, if in opposition, it is differentially compound-wound,

    compression crushers: Crushers in which the rock is subjected to a squeezing action. This group includes gyratory, jaw and smooth rolls crushers.

    competent: as defined by the Quarry Regulations 1999, in relation to a person means a person with sufficient training, experience, knowledge and other qualities to enable him to properly undertake the duties assigned to him.

    compression test: Test in which specimens of the material under test (eg concrete) are subjected to increasing compressive force until they fail by buckling, cracking or disintegration.

    compressor: see air compressor.


    concaves: The cast manganese liners of the chamber of a gyratory crusher.

    concrete: A mixture of stone, sand, water and a binder, usually Portland cement, which hardens to a stone-like mass.

    concrete aggregates: Grading limits for concrete aggregates are given in BS EN 12620

    condition: In relation to a planning consent, a limitation imposed by the MPA to achieve some desirable effect in relation to the permitted development.

    condition monitoring: A series of engine assessment techniques based on oil testing.

    conditioning: The preparatory stage in the flotation process in which the reagents are brought into intimate contact with the solids of the pulp.

    conductivity meter: An instrument which gives a continuous readout of the chloride ion ******* of wash water used in marine aggregate processing.

    conduit: Pipe or trough to contain and protect cables or wires.

    Cone Crusher

    cone crusher: A gyrating compression crusher with both fIxed and moving crushing members of greater diameter at the bottom than at the top and with mainly secondary and tertiary crushing applications.

    conglomerate: A rock consisting of rounded pebbles held together by a natural cement.

    construction joints: A joint between fresh concrete and concrete which has already hardened. Concrete on either side of the joint is usually united by reinforcement crossing the joint.

    contact metamorphism: Changes brought about in a rock by contact with intruded or extruded molten igneous material.

    contactor: A device for repeatedly opening and closing electrical circuits.

    continuous asphalt plant: A heating, mixing and storage installation, particularly suited to the production of high volumes of hot-rolled asphalt. See drum-mix plant.

    Continuous Asphalt Plant

    continuous maximum rating: The load at which an electric motor can be continuously operated without overheating. abbr. cmr.

    continuous mixer: A concrete mixer which receives a ribbon feed of raw materials at one end, discharging continuously through the other end.

    contour: A line on a plan joining points of equal altitude.

    contraflow: 1 Water flow in the opposite direction to that of the mineral being treated in a washer. 2 The direction of vibration of an inclined screen to retard the passage of material along the screen.

    contraction joint: A break made in concrete work to allow for shrinkage during drying. Provision of these joints in long concrete structures prevents the formation of cracks.

    control valve: In a hydraulic system, the valve which directs the flow of oil to operate the service in the direction required and connects the opposite service line to the reservoir.

    controlled blasting: Techniques used to control overbreak and produce a competent final excavation wall. see pre splitting and cushion blasting.

    conveyor: A mechanical device for transporting material in a continuous stream. The most common type of conveyor consists of a steel frame equipped with pulleys and idlers over which a continuous rubber belt travels loaded with material being moved from quarry to plant or within the plant.

    conveyor system: A movable or stationary item of plant designed for the conveying of materials continuously from one location to another.

    coolant: Material used to remove heat from an electrical device or equipment, eg air, hydrogen, oil and water.

    co-ordinates: Rectangular co-ordinates are measured perpendicularly from axes which are at right-angles to each other. In surveying, the distances measured to the east are positive and called eastings or departures and those to the north are positive and called northings or latitudes.

    copper loss: The heat energy loss in a conductor not intended to produce heat. This loss is proportional to the square of the current passing through the conductor and its resistance.

    Cordtex: Detonating fuse.

    core: 1 The cylindrical sample of rock bored out during core drilling. 2 The part of an electromagnetic circuit situated within the winding.

    core-balance protection: A system of earth-fault protection applied to circuits in an ac electrical system having a neutral point earthed and utilizing a core-balance transformer to detect the earthleakage current.

    core-balance transformer: A form of current transformer, the primary windings of which are connected in each phase of a circuit. The flux resulting from an out-of-balance current in the primary winding induces a voltage in a secondary winding.

    core barrel: A length of pipe immediately above the bit of a rotary core drill. Double-core barrels have an inner portion mounted on a bearing so that it remains stationary and does not damage the core to the same extent when drilling is in weak friable strata.

    core box: A long wooden box divided into sections wide enough to accommodate the cores taken from a borehole in the order they are removed for retention/examination.

    core drilling: A method of rotary drilling in which a core is recovered.

    core lifter: A spring clip at the base of the core barrel which grips the core, allowing it to be broken off and brought out of the hole.

    core loss: see iron loss.

    cost-plus: A form of contract used for urgent work by which the client pays for on-site labour, materials and plant costs plus an agreed sum to cover the contractors overheads and profit.

    coulomb: The quantity of electricity transported in one second by a current of one ampere. Symbol: C.

    counterbalance valves: Hydraulic pressure-maintaining valves used to prevent a load causing a cylinder to move faster than under the influence of pump flow.

    country rock: The rock adjacent to a mineral vein or igneous intrusion.

    couple: A pair of equal and opposite parallel forces which act upon a single structural member or element of a machine, but not in the same straight line.

    coupling: The degree to which an explosive fills the hole. Bulkloaded explosives are completely coupled, untamped explosives are decoupled.

    cover: The thickness of concrete between the steel reinforcement and the nearest face of the concrete. Insufficient cover may lead to corrosion of the reinforcement.

    crash box: A hopper into which the material discharged from a crusher is deposited and from which it is removed by means of a feeder. This ensures that velocity is removed from the material which is then conveyed to the next stage at a controlled rate.

    Cretaceous: The final period of the Mesozoic era (144-65 million years ago).


    crimping: The action of squeezing the open end of a plain detonator, or a detonating relay, over a length of fuse.

    critical diameter: The mimimum diameter of an explosive for propogation of a stable detonation. Critical diameter is affected by confinement, temperature and pressure on the explosive.

    critical path: In network analysis the critical path is the path through the network that consists of the sum of the longest times, ie it determines the total time for the project and the completion date. It is represented by a bold line on the network.

    Cross Bedding

    cross-bedding: Laminations, in a bed of sedimentary rock, which are inclined to the general stratification.

    cross bit: see cruciform bit.

    cross-ply: Term applied to tyres having a number of casing plies, set one on another, running diagonally from bead to bead, each ply crossing the one immediately below it. This type of tyre has relatively stiff sidewalls.

    crowd: Term describing the action of an excavator bucket being forced into the rock-pile.

    crowd shovel: see faceshovel.

    crown: 1 The part of a drill bit which contains the cutting diamonds. 2 The highest portion of the cross-section of a cambered carriageway.

    Crown minerals: Minerals such as gold, coal, minerals on the sea bed etc ownership of which is vested in the Crown and may only be worked under licence issued by the Crown Estates Commissioners.

    crown wheel: The larger wheel of a bevel reduction gear.

    cruciform bit: A percussive bit having two cutting edges intersecting at right-angles.

    crusher-run: Crusher product which has not been subjected to any subsequent screening.

    crushing rolls: see roll crushers.

    cube test: Test of the compressive strength of concrete cubes which have been cast and cured under standard conditions as detailed in BS 1881:Part 116.

    cuber: Part of an automated concrete block-making system which stacks blocks ready for packaging.

    cumulative curve: Any curve expressing the results of combining successive relative density fractions or size fractions.

    curing: The process of preventing the loss of moisture from concrete while maintaininng a satisfactory temperature until it has developed the necessary degree of impermeability and strength.

    current: A movement of electric charge. The direction of a current is taken as being that of the positive charges. Symbol:A. Unit:ampere.

    current assets: Assets which will be owned for only a short period, usually less than a year from the date of the balance sheet, eg the value of stocks and stores, work in progress and the bank balance.

    current liabilities: Liabilities which, it is expected, will be paid off within 12 months of the date of the balance sheet, eg outstanding suppliers accounts, bank overdrafts, tax liabilities etc.

    current rating: 1 The current rating of a fuse is that current, less than the minimum fusing current, stated by the manufacturer as the current that the fuse link will carry continuously without deterioration, in accordance with relevant clauses of specification. 2 The safe working current of a conductor, eg a cable.

    Current Transformer

    current transformer: An instrument transformer. The primary winding of the transformer is connected in series with the load and the lower current induced in the secondary winding, across which is connected an ammeter, is proportional to that in the primary.

    cushion blasting: A surface blasting technique used to produce competent slopes. The cushion holes, fired after the main charge, have a reduced spacing and employ decoupled charges.

    cusum: A method of graphical presentation of the cumulative sums of two related sets of data. An example of its use is for monitoring the quality of ready-mixed concrete which allows variation of the cement ******* to maintain the compressive strength of a standard mix at the desired level.

    cut and fill: A surface mining technique in which overburden is dumped to occupy the void created by the removal of the mineral.

    cut-back bitumen: Bitumen whose viscosity has been reduced by the addition of a flux, usually a petroleum oil.

    cut-off shot: A shot in a delay round in which the charge has been wholly or partially exposed to the atmosphere by reason of the detonation of an earlier shot in the round.

    cut stone: Stone chiselled into a desired shape.

    cycle: The repetition of a variable quantity recurring in equal intervals of time.

    cycle of operations: A series of several separate operations in a system of quarrying carried out in a predetermined order.

    cyclone: A conical classifying device into which pulp is fed so as to take a circular path. Coarser and denser fractions of solids report to the apex of the cone, while finer particles overflow from the central vortex. Cyclones are also used for dewatering and in the removal of dust particles from air and other gases.

    cyclone dust collector: An apparatus for the separation by centrifugal means of fine particles suspended in air or gas.

    cyclone dust separator: A cone shaped air-cleaner which removes dust from air by centrifugal separation; a rapid vortex motion is applied to the air stream, causing dust to be thrown radially to the sides of the chamber.

    Cyclone Dust Separator

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    DAPS: abbr. The Doncaster Assisted Private Study scheme.

    dc: abbr. see direct current.

    DCF: abbr. discounted cash flow.

    DMS: abbr. 1 Dense-media separation. See heavy-media separation. 2 Diploma in Management Studies.

    DTH: abbr. down-the-hole. See down-the-hole drilling.

    DTS: abbr. dense tar surfacing.

    database: A collection of itemized records held in an organized filing system commonly in a computerized form.

    dash pot: A device for damping-out vibration or retarding motion in one direction. It consists of a piston fitting loosely in a cylinder of oil or other fluid.

    datum: An assumed reference surface from which the measurement of reduced levels are measured.

    dead load: The weight of the structure and any loads fixed to it.

    deca-: A prefix meaning ten times.

    deci-: A prefix meaning one tenth.

    decibel (dB): Unit for comparison of intensities of sounds and of power in electrical communications circuits.

    Deck Charge

    deck charge: A charge which is divided into several separate components, down a blasthole, by inert material.

    declination: The angular variation, in degrees, of the magnetic compass needle, uninfluenced by local causes, from the true north and south. This varies from one locality to another and in any given locality it varies with time.

    decoupling: When the explosive charge is not in full contact with the rock, so reducing the effect of the explosion.

    deflection: The intentional alteration of the course of a borehole in directional drilling.

    deflection wedge: A wedge-shaped tool inserted into a borehole to direct the bit along a prescribed course.

    delay detonator: A detonator in which there is a designed interval of time between the application of an electric current to the detonator and its detonation.

    Delay Element

    delay element: The part of a delay detonator interposed between the fusehead and the priming charge.

    delay firing: The firing of several shots in sequence, at designed intervals of time, usually by means of delay detonators, detonating relays or sequence switches.

    delay interval: The nominal period between the firing of successive delay detonators in a series of shots.

    delay relay: see detonating relay.

    delta connection: A three-phase electrical connection in which the windings are connected in a closed ring and the supply connected to or taken from the junctions.

    dense tar surfacing: A hot-process wearing course consisting of aggregate, filler and road tar, in such gradings and proportions that when hot can be spread and compacted, to provide a close-textured impervious mixture. abbr: DTS.

    dense-media separation: see heavy-media separation.

    density: The mass of unit volume of a substance. Units: kg/m3.

    departure: The distance in metres of a point east or west of a north-south axis. May also be referred to as an easting, in which case all distances measured to the east are regarded as being positive. See co-ordinates.

    depreciation: A method of charging against annual costs, over the expected life of an asset, its original total cost. This can be done by equal or decreasing increments.

    depressants: see regulators.

    derrick: A lifting device which takes a number of forms including: a pole, held in position by a number of guy ropes, at the top of which a hoisting rope passes over a pulley; and a three-legged framework over a borehole, used primarily to allow lengths of drill rod to be added to the drilling column.

    designed mixes: Mixes for which the concrete producer is responsible for selecting the mix proportions to produce concrete with the required performance. Bituminous mixes can also be designed to meet stated parameters (void *******, stability etc).

    detonating fuse: A fuse containing a core of detonating explosive. It has a velocity of detonation of approximately 6,500m/s and is used extensively in quarrying and opencast blasting operations. It is manufactured in two main grades: Cordtex or Pentaflex 12 which will initiate commercial explosives but require a primer for ANFO and slurries, and the higher-powered Superflex or Pentaflex 40 which will initiate them without the use of a primer but are intended for down-the-hole use only.

    detonating relay: A device used intermediately in a detonating fuse circuit to obtain a short time delay.

    detonation: The action of converting the chemicals in an explosive charge to gases at high pressure, by means of a self-propagating shock wave passing through the charge.

    detonation impedance: The resistance of rock to blasting.

    detonator: A device for producing detonation in a high-explosive charge, and initiated by safety fuse, electrical current or shock.

    detrital deposit: A sandy or gravelly deposit formed by river or sea action, consisting of materials eroded from earlier deposits.

    development: Work done in a quarry to obtain access to the mineral or to facilitate the opening-out of a new working area.

    deviation: 1. The wandering of a borehole from its intended course. 2 The difference between one value of a set and the average. See standard deviation.

    Devonian: A period of the Palaeozoic era spanning the time from 395 to 360 million years ago.

    diamond drilling: A method of rotary drilling in rock, usually for exploratory purposes, using hollow diamond-crowned bits to obtain a core for examination.

    Diamond Saw

    diamond saw: A circular or reciprocating saw with a diamondbonded cutting edge used to cut concrete, stone, slate and other hard materials.

    diaphragm: The fitting in the telescope of a surveying instrument which carries the graticule.

    diaphragm pump: A reciprocating pump in which a flexible diaphragm set between two non-return valves is clamped at its edge and at its centre is moved to and fro through a short stroke.

    diecasting: Casting of metals or plastics in permanent moulds, made of non-deforming metal, which can be used repeatedly for producing large numbers of castings.

    diesel engine: An internal combustion engine running on a light fuel oil which is pumped into the cylinders and ignited solely by the high compression in the cylinders; no electrical spark is required. The operating cycle was invented by Rudolf Diesel (1858-1913), a German engineer.

    differential gear: A gear permitting relative rotation of two shafts driven by a third. The two driven shafts are independent but the sum of their rotation rates is constant.

    differential pulley block: Lifting tackle consisting of two chain wheels of different diameters turning together on the same shaft and over which an endless chain passes. The chain wheel is rotated by a hanging loop and this shortens a second loop which supports the pulley to which the load is attached. A large mechanical advantage is obtained and the chain cannot run back.

    diggability: A reference to the excavation characteristics of the rock to be dug.

    dimension stone: Stone cut to regular shapes and sizes for use in the construction industry.

    diode: A valve with only two electrodes - an anode and a cathode.

    diorite: A coarse-grained plutonic igneous rock with a high ******* of plagioclase feldspar. Very tough and used as concrete aggregate and road metal.

    dip: The inclination of the strata to the horizontal. See apparent dip and full dip.

    direct initiation: A method of blasting in which the primer cartridge is placed at the end of the explosive charge nearest the entrance to the blasthole and the detonator is placed at the outer end of the primer cartridge.

    direct-on-line starting: Starting in which the full supply voltage is connected directly to the motor.

    discharge valve: A valve for controlling the rate of flow from a pipe or a tank.

    discounted cash flow: A method of financial assessment of a project in which the initial expenditure and estimated future profits are discounted (reduced) year by year either (a) by the estimated interest rate of borrowing to give the Net Present Value of the project over its estimated useful life , or (b) by such a discount rate that the NPV is zero over the useful life of the project.

    discrimination: Means by which protective devices operate circuitbreakers to disconnect faulty apparatus from the system but leave sound electrical equipment to continue to function.

    displacement: 1 The volume swept by a piston moving through its full stroke in a cylinder. 2 The weight of water displaced by a floating vessel or by a submerged solid.

    displacement pump: Any pump with a pulsing action, produced by compressed air, steam or a plunger.

    dolerite: A medium-grained basic igneous rock occurring as intrusions, eg dykes and sills. A typical dolerite contains plagioclase, augite and ilmenite. Used in road making and as concrete aggregate.

    dolomite: A mineral composed of calcium magnesium carbonate or a rock consisting predominantly of that mineral.

    dome: A structure in which the strata dip outwards on all sides.

    double-cage motor: A type of squirrel-cage motor having a rotor with two separate cages, a high-resistance cage occupying slots on the periphery of the rotor and a low-resistance cage set deeper in the rotor. Such motors provide improved starting characteristics compared with single-cage motors of similar rating.

    double-roll crusher: see roll crushers.

    Double Toggle Jaw Crusher

    double-toggle jaw crusher: A jaw crusher in which the motion of the eccentric shaft is transmitted through the pitman to a toggle joint, formed by two toggle plates hinged together, at its lower end. The opposite end of one plate is hinged on the back plate and the opposite end of the other at the load point, ie the jawstock. The effort applied at the common hinge point causes the obtuse angle between the plates to increase and considerable force is produced at the jawstock.

    Drag Bits

    down-the-hole drill: A percussive drill in which the percussive mechanism (hammer) is located immediately behind the drill bit.

    down throw: The amount, measured vertically, of downward displacement of beds caused by a fault.

    drag bit: A rotary bit which has two or more cutting blades or wings with hardfaced cutting edges.

    dragline: An excavator the bucket of which is suspended by means of a wire rope from the end of a long light boom or jib. The bucket is filled by dragging it towards the machine. Draglines usually dig below the level on which they stand and a good operator can cast the spoil considerably beyond the end of the jib. See walking dragline.

    draw-bar pull: The tractive effort exerted by a tractor or a locomotive which is transmitted through draw-bars to the vehicles towed behind it.

    dredge: A barge or pontoon carrying digging buckets or suction pump, used for excavating alluvial deposits below water.


    dressed stone: Stone which has been squared and smoothed on the face.

    drift: 1 Superficial deposits such as alluvium, boulder clay, glacial gravel, peat etc. 2 An inclined tunnel from the surface to the mineral deposit being developed.

    drift map: A geological map showing all superficial deposits, ie a true picture of the ground as it exists.

    drifter: A heavy percussive drill requiring some form of rigid mounting.

    drill boom: An adjustable arm projecting from the drill carriage to carry a drill and hold it in selected positions.

    drill carriage: A vehicle on which one or more drill booms are mounted to permit the drills to be brought easily to their work and be removed before blasting.

    drill cradle: The metal channel on which a heavy drill is fed forward as drilling proceeds.

    drill head: The assembly which applies the drilling pressure and rotation to the drill rods.

    drill rig: Any means of supporting a rock-drill at work.

    drill steel: see rod and stem.

    drill string: The string of tools commonly used in rope drilling, namely: rope, socket, sinker bar, sliding jars, drill stem and drill bit.

    drilling column: The column of drill rods to the end of which the core barrel and/or bit is attached.

    Drop Ball Method Of Breakage

    drop-balling: Rock breakage by dropping a heavy weight on a cable suspended from a crane or excavator jib or simply by dropping a ball from a shovel bucket.

    drum-mix plant: A form of continuous asphalt plant in which the heated aggregate and bitumen are mixed in a rotating horizontal drum.

    dryer: A means of heating aggregate before mixing with bitumen. It may take the form of a long drum (a continuous dryer) or a batch heater.

    drying shrinkage: Contraction which takes place in concrete as hydration occurs and in some aggregates which shrink on drying out.

    drystone: Quarried and processed stone which is unbound with bitumen or cement.

    duct: A brick or concrete trench or a protective pipe along which cables or pipes pass through the ground.

    dumper: An off-highway self-propelled wheeled machine, having an open body, which transports and dumps or spreads material. Loading is performed by means external to the dumper.

    dumptruck: An on-site tipping vehicle of up to 200 tonnes carrying capacity used for the transport of excavated mineral or overburden.

    dumpy level: A type of levelling instrument in which the telescope is rigidly connected at right-angles to the vertical spindle, so that its axis is horizontal.

    dust: A term which, when used to describe dispersions of small solid particles in air or other gases, refers to those particles which are smaller than 76 micrometers. In construction work, the term generally applies to -3mm rock product after crushing.

    dust collectors: see settlement chambers, cyclone dust separators, venturi scrubbers, spray scrubbers, fabric filters and electrostatic precipitators.


    dyke: A more or less perpendicular wall-like igneous mass intruded into other rocks.

    dynamite: A general term relating to explosives in which the principal constituent, nitroglycerine, is contained within an absorbent substance.

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    : Nov 2005
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    EDM: abbr. see electronic distance measurement.

    EIA: abbr. see. environmental impact assessment.

    emf: abbr. see electromotive force.

    earth electrode: A conductive part or group of parts in intimate contact with, and providing an electrical connection with, earth.

    earth-fault current: A current that flows from phase conductors to earth or protective conductors etc from the point of an insulation breakdown.

    earth-fault protection: A system of protection designed to cause the supply to an electrical circuit or system to be interrupted automatically when the leakage current to earth exceeds a predetermined value.

    earth-leakage protection: see earth-fault protection.

    earth testing: Tests to ensure that the resistance between the earth electrodes (ie earth plates, rods etc) and the general mass of earth does not exceed a prescribed value.

    earth-leakage circuit-breaker: A device which disconnects the electricity supply if the voltage on non-current-carrying metalwork or the out-of-balance current in the supply due to leakage exceeds a predetermined value.

    earthing conductor: A protective conductor connecting the main earthing terminal or main earthing bar to the earth electrode. Also used to describe an earth wire bonded from the metal work of an isolating switch (for example) to the cable armouring feeding it.

    easement: A liability attaching to land, whereby some person other than the owner has certain clearly defined rights over it and in perpetuity. Alternatively, a right over land granted in perpetuity by the owners to some person for a specific purpose, eg passage, laying of mains drainage etc.

    easting: see departure.

    eccentric: Displaced with reference to a centre, eg the eccentric section of the shaft generating the motion of a four-bearing screen.

    eddy current: In most cases unwanted currents generated by a magnetically induced electromotive force in a closed conductive path, such as the core of an electric machine, resulting in a waste of energy.

    effective value: The root-mean-square value of an alternating current or voltage.

    efficiency: 1 The ratio of useful output energy to input energy. 2 The efficiency of a simple machine is defined as the ratio of the force ratio to the movement ratio. See also screening efficiency.

    elastic limit: The stress level above which a material remains permanently deformed when the stress is removed.

    electromagnet: A current-carrying coil with a soft iron core, which has appreciable magnetic effect only when there is a flow of current.

    Electromagnetic Induction

    electromagnetic induction: The production of an induced voltage in a circuit by means of the magnetic flux cutting the circuit. In order for an induced current to flow in a closed circuit the conductors and the magnetic field must move relative to each other.

    electromagnetic screen: A screen to which is attached an electrically operated vibrator unit consisting of an armature and a stator connected to a halfwave rectified single-phase ac supply, which imparts a linear motion, usually of high frequency and low amplitude, to the screen.

    electromotive force: The voltage applied to an electrical circuit which causes current to flow.

    electronic distance measurement: A very accurate method of measuring distance by means of an electronic device. Most EDM instruments are operated by infra-red light or laser, with the beam being directed at a target which may be some kilometres away, and give a direct reading with an accuracy of 1 in 10000 or better.

    electrostatic precipitator: An apparatus for removing dust from dust-laden air by creating electric charges on the dust particles, causing them to be attracted to a collecting plate.

    element: In relation to time study, a distinct part of an operation selected for convenience of observation, measurement and analysis. BS 42003.

    Elevating Scraper

    elevating scraper: A self-loading bowl scraper able to operate without the help of a pusher dozer except in very difficult conditions. It is fitted with an elevating conveyor with flights at regular intervals which, as the scraper moves forward, carry the material sliced off from the ground up into the bowl.

    elevation: 1 A view of a component or assembly drawn in projection on a vertical plane, eg an end elevation. 2 The height of a point above sea level.

    elevator: see bucket elevator.

    elutriation: Process of dividing fine particles into size fractions according to their rate of fall through an upward current of water.

    eluvial deposit: Rocks which have disintegrated through natural causes but which, unlike alluvial material which is transported away by water, have remained in situ.

    empirical formula: A formula based on experience or the results of experiments, not deduced from theoretical considerations.

    emulsion: 1 Bitumen emulsions, in which the bitumen is dispersed in water, through the use of emulsifying agents, as small globules permitting use at lower temperatures. 2 Explosive emulsions are mixtures of fuel and oxidizers (mainly nitrates) in a ratio of approximately 1:10, which have good water resistant properties and chemical stability. Emulsion/ANFO blends can be used to suit particular circumstances.

    energy: The capacity to do work. Energy is expended when work is done. Unit: joule (J). Forms of energy include: mechanical, electrical, thermal, chemical etc.

    energy factor: The amount of explosive energy required to break a unit volume of rock (MJ/m3) which may be used as a blast design criterion.

    environmental impact assessment: Study of the potential environmental benefits and disbenefits arising from a development, usually conducted before a planning application is submitted.

    Eocene: An epoch of the Tertiary period between 54 and 38 million years ago.

    epicyclic gear: A system of gears in which one or more gear wheels travel round the inside or outside of another gear wheel, the axis of which is fixed.

    equipotential bonding: Electrical connection putting various exposed conductive parts and extraneous conductive parts at a substantially equal potential.

    equity: The shares of a company which do not bear fixed interest, ie the ordinary shares.

    equivalent continuous sound level: The constant sound intensity level which in the course of continuous exposure for 8h would result in the same energy dosage as that due to the actual exposure. abbr. Leq.

    erosion: The wearing away of parts of the Earths surface by the action of natural agents such as ice, water and wind.

    evaporites: Rocks, such as anhydrite, rock salt, potash, salt etc, formed by evaporation of lakes or seas.

    excavator: Self-propelled crawler or wheeled machine with an upper structure capable of rotation, which excavates, swings and discharges material by the action of a bucket fitted to the boom and arm, or telescoping boom, without moving the chassis or undercarriage during any part of the working cycle of the machine.

    excitation time: The minimum time for which an electric current must flow in the fusehead of a detonator to ensure its ignition.

    expanded metal: A metal network made by stamping and stretching sheet metal to form an open mesh. Used as reinforcement in concrete, in the manufacture of safety guards for machines etc.


    exploder: A device designed specifically for producing an electric current for firing detonators. All exploders used in quarries must have a removable handle or key.

    explosives store: Premises registered in accordance with section 21 of the Explosives Act 1875; a magazine licensed in accordance with sections 6 to 8 or a store licensed in accordance with section 15 of the 1875 Act.

    explosives strengths: see bulk strength and weight strength.

    explosives supervisor: the appointed person in overall, day-to-day charge of work with explosives who must have successfully completed a course of training.

    exposed aggregate: A decorative concrete finish in which the mortar is removed to expose the coarse particles at the surface.

    extrapolation: The continuance of the line of a graph beyond the points for which values are available, in order to estimate values beyond the range of those points.

    extrusion: The process of producing rods, tubes and various solid and hollow sections, by forcing suitable metals and plastic materials through a die.

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