S — Dictionary of Quarrying Terms

SAE: abbr. Society of Automotive Engineers.

SAE numbers: Society of Automotive Engineers (US) classification for petroleum-based motor oils. The oils are classified into viscosity grades but the SAE numbers are not viscosity values, they serve merely to identify the various grades.

SAGA: abbr. Sand and Gravel Association. The former trade federation for sand and gravel producers now amalgamated with BACMI as QPA.

SAMSA: abbr. Silica and Moulding Sand Association. The trade federation for producers of special sands.

SDT: see ‘self-discharge train’.

SHE: abbr. Safety, Health and Environment

SI units: Systeme International d’Unites is an internationally accepted system of units of measure together with their symbols. It is founded on seven basic quantities: length, mass, time, electric current, temperature, luminosity and amount of substance, each of which have a related basic unit: metre, kilogramme, second, ampere, kelvin, candela and mole. There are also many derived units, eg newton, joule, watt, with their agreed symbols.

SSAF: abbr. statement of source and application of funds. An analysis of a company’s financial resources and their use to show changes in the cash position.

SSSI: abbr. site of special scientific interest.

safety fuse: A fuse with a black-powder core, having a prescribed covering and designed to burn at a specified speed.

sampling: Separation of a representative fraction of mineral or product for testing or checking purposes.

sand: 1 A naturally occurring granular material in the size range O.06mm to 2mm, often containing a high proportion of quartz. 2 Concreting sand is a fine aggregate having a nominal upper size limit of 4mm.

sand casting: The production of shapes by pouring molten metal into a shaped cavity formed in sand.

sandstone: A bedded rock composed of grains of sand, principally of quartz, cemented naturally together.

scalar quantities: Quantities that have only magnitude, eg mass, temperature and volume.

scaled distance: A ratio used to predict ground vibrations. As commonly used in blasting, scaled distance is the ratio of the distance from the blast, in metres, to the square root of the maximum instantaneous charge weight, in kilogrammes.

scalping: 1 Generally to remove inferior top rock and clay from the main feed to a mineral-processing plant. 2 The action of rough screening to remove an oversize fraction.

scarifier: A self-propelled or towed implement used for breaking-up a surface to a regulated depth.

scarifying: The systematic disruption or loosening of the top of a road or other surface by mechanical or other means.

scavenger cells: Flotation cells used in the removal of the last recoverable fraction of values before the final tailing is discarded.

schist: A metamorphic foliated crystalline rock containing mica and various other minerals with bands that are often wavy and contorted.

scraper: see ‘bowl scraper’.

scree: Accumulation of angular pieces of rock near the base of a steep hillside.

screen capacity: The maximum tonnage rate at which a screen performs satisfactorily the size separation required.

screen cloth: A mesh of wires woven in a consistent manner to form apertures.

screen deck: A surface provided with apertures of specified size for carrying out the operation of screening.

screen plate: A plate provided with apertures of specified size for use as a screen deck.

screening: The separation of solid materials of different sizes by causing part to remain on a surface provided with apertures through which the remainder passes.

screening efficiency: Screen undersize recovery efficiency is the mass of undersize passing through the screen expressed as a percentage of the mass of undersize in the feed.

screw conveyor: A conveyor consisting of a central shaft with helical paddles or a complete helical screw rotating within a stationary tube or trough filled with the material being conveyed.

screw shackle: see ‘turnbuckle’.

scrubber: A mineral-processing machine in which fine fragments and clay are washed from the surface of larger particles by a vigorous scrubbing action. One type of scrubber consists of a cylinder rotating at high speed, resulting in the material being subjected to a cascading action. See also ‘venturi scrubber’ and ‘spray scrubber’.

scuffing: Wear in the form of torn patches, with blobs of material transferred from one surface to the other, caused by localized welding due to high temperature at points of close contact, the welds being immediately torn apart as movement proceeds.

seam: A layer or bed of mineral; generally applied to coal.

secondary blasting: The use of explosive to break into smaller pieces rock already blasted.

secondary crushing: The reduction of material from the primary crusher to 50-60mm in larger plants, probably -40mm in smaller operations.

secondary winding: The winding of a transformer from which the output is taken.

sedimentary rock: A rock formed from materials which have been deposited as a sediment in water or on land. They include rocks formed from fragments of pre-existing rocks, deposits formed from the hard parts of organisms and salts deposited from solution.

segregation: The unwanted gravity separation of a graded aggregate caused by large particles rolling to the perimeter of a stockpile for example.

seismic prospecting: A method of geophysical prospecting in which the travel times of reflected and refracted shock waves, between small explosive charges and a series of geophones, are used to provide information about the depth and character of underlying rock formations.

seismograph: An instrument that measures and may supply a permanent record of earth-borne vibrations induced by earthquakes or blasting.

selector valve: Hydraulic direction-control valves the majority of which are of the sliding-spool type. When the spool is moved passageways are connected, or closed, to direct the oil to and from the appropriate parts of the system.

self-discharge train: An aggregate carrying train in which sets of hopper wagons discharge on to a belt conveyor which feeds a boom capable of discharging alongside the rail track. abbr. SDT.

self-excitation: The production by an electromagnetic machine of a working flux, without any external source of magnetizing current.

self-inductance: see ‘inductance’.

semi-conductor: A material which has a resistivity which is high but not high enough to be classed as an insulator, ie it exhibits properties intermediate to those of conductors and insulators.

sensitivity: A measure of an explosive’s susceptibility to detonation upon receiving an external impulse such as impact, shock, flame or friction.

sensitizer: An ingredient used in explosive compounds to promote greater ease of initiation or propagation of the detonation reaction.

sentry: A person posted at an approach point to where a shot is about to be fired. He is authorized to stop all persons from entering the danger zone and should not leave the place where posted until the all-clear signal is given or until so directed by the person who did the posting.

sequence control: A method of control whereby, once action has been initiated, a number of electrical circuits will automatically function in a prescribed order.

sequence interlock: An interlock provided between a number of electrical circuits, which are required to function in a prescribed order, and which prevents a circuit from being operated unless the preceding circuit has completed its part of the sequence.

sequential blasting machine: A series of condenser discharge blasting machines in a single unit which can be activated at various accurately timed intervals following the application of an electric current.

series firing: The firing of detonators in a round of shots by passing the total supply current through each of the detonators connected in series.

series-wound motor: A dc motor in which the armature and field windings are connected in series with the supply.

servo system: A system which aids human action by magnifying a small effort, usually by hydraulic means.

sett paving: A surfacing consisting of rectangular blocks of stone laid in a regular manner on a prepared roadbase.

setting: The distance between the fixed and moving members of a crusher measured at the discharge opening. This distance is known as the open-side setting (OSS) when the members are farthest apart and as the closed-side setting (CSS) when they are nearest together.

settlement chamber: A relatively simple device in which grit and large dust particles are removed from gases as they pass through a chamber of large cross-section, in which the velocity of flow is reduced, allowing time for them to fall out of the gas stream under the action of gravity.

settling pond: A reservoir of still water in which fine material is allowed to settle.

shale: A fissile indurated sedimentary rock consisting largely of clay minerals.

shank: 1 The end of the drill rod or stem that engages with the chuck of the drilling machine. 2 The pointed tool which when fitted to a bulldozer can be forced into the ground hydraulically in order to rip the ground as the bulldozer moves forward.

share capital: the money invested in a business by risk-taking shareholders.

shear force: The force transverse to a beam at a given section tending to cause it to shear at that section. It is equal to the algebraic sum of all the vertical forces on either side of the section.

shear legs: A pair of poles connected at the top from which a pulley is hung over which a rope is passed for the purpose of lifting heavy loads.

sheave: A grooved pulley wheel for use with steel-wire ropes, vee-belts etc.

shell-and-auger drilling: A type of percussive drilling used for site investigation which is particularly useful in obtaining samples of sand and gravel from below the water table but, by using a chisel in conjunction with the shell, the hardest rocks may be penetrated. The weight of the tools and rods is carried by shear legs or three-pole derrick but the drilling rig may also be truck-mounted.

shim: A thin strip of metal, used singly or in numbers, to take up space between clamped parts.

shock tube: The term applied to detonating systems such as Nonel.

shock wave: A pressure pulse that propagates at supersonic velocity.

short ton: The US ton of 2,000 lb.

short-delay detonator: A detonator in which the delay interval is expressed in milliseconds.

short-time rating: An electric machine rating which allows for cooling between working periods resulting in a rate higher than the cmr value. The rating-plate shows a designation of either 1h or 1/2h which is the time the machine can operate under rated conditions starting from ambient temperature.

shot: An explosive charge contained within a blasthole. A single shot or a series of shots fired as part of a blast.

shotfirer: A person appointed by the manager in accordance with regulation 26 of the Quarries Regulations 1999. The person appointed must have such training, knowledge and experience as are appropriate to ensure that he is competent to fire shots safely.

shunt-wound motor: A dc motor in which the armature and field windings are connected in parallel with respect to the supply.

shuttering: The casing into which concrete is poured and in which it remains during the period of setting and hardening.

sieve analysis: The process or the result of the division of a sample into size fractions by the use of laboratory test sieves.

sieve bend: A curved static screen used for dewatering and the removal of fines from slurries.

sill: An intrusive sheet of igneous rock parallel or nearly parallel to the general stratification.

silo: A tall cylindrical construction serving as a container for the storage of loose free-running material.

silt: A fine-grained sediment having a particle size intermediate between that of fine sand and clay.

Silurian: A period of the Palaeozoic era between 435 and 395 million years ago, and the corresponding system of rocks.

Simpson’s rule: A method of calculating an irregular area.

single-row blasting: The conventional system of blasting in rock quarries in which the blastholes are arranged in a single line parallel to the working face. See ‘azimuth’ for diagram.

single-toggle jaw crusher: A jaw crusher in which the jawstock is suspended from an eccentric shaft and is braced by a toggle from the back plate so that the jawstock moves through an elliptical path. See ‘jaw crusher’.

sintering: In powder metallurgy, the mixing of metal powders having different melting points and then heating the mixture to the temperature approximately equal to the lowest melting point of any of the metals included. In sintered carbides, powdered cobalt, having the lowest melting point, acts as the matrix which holds together the unmelted particles of hard carbides.

siphon: A system of pipes and valves which may be used to convey water to a lower level over intervening higher ground without the use of a pump.

skid-resistance tester: The equipment used to determine the PSV of an aggregate, by testing the coefficient of friction between a pendulum-mounted rubber pad and either a laboratory-prepared sample or directly on a road surface.

skid-steer loader: A miniwheeled loading shovel useful for clearing spillage in confined areas.

skirt: A rubber or metal plate designed to prevent spillage, particularly at the feed point of a belt conveyor.

slab: Plain or reinforced concrete which may itself serve as a running surface and roadbase or solely as a roadbase.

slag: The residual product following the primary smelting process for iron, steel, copper etc. When cold it is generally rock-like and can be used as roadmaking material.

slate: Shale lowly metamorphosed by stress and moderate temperature; tough, fine-grained and capable of being split into thin plates at an angle not related to the bedding plane. Used as roofing slates and for decoration of buildings etc.

sledging rolls: see ‘roll crushers’.

slewing: Rotation of the jib or boom of a crane or excavator.

slickensides: The striations, grooves and polish on fault and shear surfaces caused by the movement of one rock mass against another.

slide rails: Steel or cast-iron mounting for an electric motor driving a machine through a belt-drive. As the belt stretches, the motor can be moved along the rails to take up the slack.

slider bearings: Bearings which allow linear motion with load forces both parallel and perpendicular to the plane of sliding.

slimes: Waste fines usually in the form of clay particles. Desliming involves the removal of very fine material from wash water or slurry.

slip: The difference in speed between the rotor and stator field of an induction motor expressed as a fraction of the speed of the rotating stator field.

slip ring: A conducting ring on the shaft of an electric machine which is connected to the end of a winding and rotates with it. A stationary brush resting on the slip ring allows contact to be made with an external circuit.

slip-ring motor: see ‘wound-rotor motor’.

slugger rolls: A type of roll crusher employing a combination of impact, shear and pressure to break soft friable rocks and wet sticky material.

slump test: The test most commonly used to measure the workability of freshly made concrete. A conical mould is filled with concrete, rammed and then inverted and emptied over a flat plate. The slump is the difference between the height of the mould and the highest point of the concrete. Changes in the slump may indicate changes in materials, water content or in the proportions of the mix. BS 1881.

slurry: A suspension of mineral particles in water.

slurry explosives: First developed as a result of attempts to waterproof, strengthen and sensitize ammonium nitrate. Slurries are available in a range of strengths and can be pumped into place or loaded in plastic film or cartridged.

slurry seal: A viscous mixture of bitumen, fine aggregate, filler and water used in repair and resurfacing work.

smoke: Visible cloud of dispersed particles, either solid or liquid, formed by combustion or condensation, 5µm or less in size.

smooth blasting: A delay blasting technique for cutting clean walls in excavations, in which closely spaced peripheral holes are fired simultaneously at least one delay period after the last charges of the main blast (also known as trim blasting).

smoothing: The removal, by means of capacitors and inductors, of ripples from a rectified electric power supply.

snub drum: A belt-conveyor drum the function of which is to increase the angle of lap between the driving drum and the belt in order to increase the adhesion available for driving.

socket: The end of a shothole which remains after the firing of a shot.

software: General term for programming or compiling accessories used for computing or data-processing systems.

soil cement: A natural soil or artificial fine-graded material such as slag fines, pulverized fuel ash etc which has been stabilized or strengthened by the addition of cement.

soil mechanics: The systematic study of the nature and behaviour of soils including their classification, composition, consolidation, strength and the active and passive pressures in them.

solenoid: A coil of insulated wire for connection in an electrical circuit to produce a concentrated magnetic field. Solenoids are used in devices such as contactors and relays to produce a force of attraction.

solid map: A geological map showing the position and nature of the solid rocks, both outcrops and rocks below any superficial deposits.

sound-intensity level: The intensity of sound, expressed in decibels above an arbitrary level, ie the rms pressure corresponding to the threshold of hearing, 20 x 10^-6 N/m².

soundness: A term used to describe an aggregate’s resistance to weathering. Tests are either by repeated immersion and drying in a saturated solution of sodium or magnesium sulphate or by repeated freeze/thaw cycles.

spacing: The distance between a pair of holes in a line of holes, measured at right-angles to the burden and parallel to the face.

special prescribed mixes: Concrete mixes where the purchaser specifies his own required mix proportions in kilograms of each constituent.

specific gravity: see ‘relative density’.

specific heat capacity: The quantity of heat required to raise the temperature of 1kg of a substance by 1K Units: J/kgK.

specific heat of fusion: The amount of heat required to change unit mass from a solid at the melting point to a liquid at the same temperature. Units: J/kg or kJ/kg.

specific heat of vaporization: The amount of heat required to change unit mass from liquid at the boiling point to gas at the same temperature. Units: J/kg or kJ/kg. See ‘latent heat’.

speed: The rate of covering distance.

spherical roller-bearing: A roller-bearing constructed so as to provide a degree of self-alignment.

spider: The bridge across the top of a gyratory crusher in the central boss of which is housed the bearing carrying the upper end of the shaft on which the head is mounted.

spiral concentrator: A helical conduit of modified semicircular cross-section. A pulp feed of between 15% and 45% solids by weight and in the size range 75μm to 3mm is introduced at the top of the spiral and, as it flows downwards, the coarsest and heaviest particles are concentrated on the inner side of the stream.

splice: A joint by interweaving or overlapping the ends as used to join electric cables and conveyor belting respectively.

splines: Narrow keys formed integral with a shaft produced by milling longitudinal grooves in the shaft and used instead of keys for maximum strength.

spotting: The positioning of a vehicle ready for loading.

spray scrubbers: Scrubbers of various types which remove dust from gases by the introduction of a spray of liquid into the gas flow, so that dust particles are trapped in water droplets and removed as a sludge.

springing: A blasting method in which a succession of charges is fired in a blasthole to open up a chamber. This is now prohibited in quarries.

sprocket: A toothed wheel used for chain drives.

spud: A steel column on a dredger which is raised or lowered from the bed to serve as an anchor. A dredger has two spuds, one at each side of the stern.

squirrel-cage motor: An induction motor having a rotor with a squirrel-cage winding, ie a series of bars accommodated in slots in the rotor, all the bars being connected at each end to a common conducting ring. This type of motor is most reliable but has a poor starting torque.

stability: The ability of an explosive material to maintain its physical and chemical properties over a period of time in storage.

stadia hairs: Two horizontal hairs, one on either side of the central cross-hair, fitted to the diaphragm of a telescope for use in tacheometry.

staggered pattern: A pattern of blastholes in which holes in each row are drilled between the holes in the preceding row.

standard costing: A costing and cost-control technique applied to detailed operations and the application of standards to particular tasks of work.

standard deviation: The root of the average of the squares of the differences of all the observations from their mean. Used as a measure of the spread of a series of values from their mean.

star connection: A three-phase connection in which all the corresponding ends of the phase windings are connected to a common point, the star point.

star point: The point at which, in star connection, the ends of the windings are joined together, and sometimes to earth.

star/delta starting: A method of reduced voltage starting of three phase motors. The starter connects the six terminals of the three stator windings in star for starting and in delta when the motor is running. The starting current and torque are one third of the values obtained when direct-on-line starting is used.

static friction: The value of the limiting friction just before movement occurs.

statics: The study of forces and bodies at rest.

stator: The stationary part of a machine. A term usually applied to the stationary magnetic parts and windings of an ac machine.

stellite: Alloy used for the hardfacing by welding of surfaces subjected to heavy wear.

stem: 1 A bar to the forged end of which is brazed a hard metal bit for drilling. 2 To insert and pack stemming in a drill hole.

stemming: Inert material packed between the explosive charge and the outer end of the shothole, or between adjacent charges in deckcharging.

stemming rod: A non-metallic rod used to push explosive cartridges into position in a shothole and to ram tight the stemming.

steradian: The solid angle which, having its vertex at the centre of a sphere, cuts off an area of the surface of the sphere equal to that of a square with sides equal to the radius of the sphere. Symbol: sr.

stop valve: A valve for turning on or shutting off completely a supply of liquid.

straddle loading: A method of loading bowl scrapers which involves first taking cuts along alternate strips, leaving the centre strips to be loaded after those on either side. This system helps in obtaining full loads in wet conditions when traction is poor.

strain: The ratio of the increase in length of a piece of material to its original length when it has been distorted, within the elastic range, by the forces acting on it. Units: none.

strainer: The perforated cylindrical or dome-shaped metal covering of the end of a pump suction pipe which prevents the entry of solids and fibrous material.

stratigraphy: The study of the historical succession of geological formations.

stratum: A single bed or layer of rock.

strength of concrete: Normally specified as the compressive strength of cubes, either 100 or 150mm, made from fresh concrete. The tensile strength of concrete is generally taken to be about one tenth of its compressive strength. See ‘cube test’.

strengths of explosives: See ‘bulk strength’ and ‘weight strength’.

stress: The force acting on unit area of a material. Units: N/mm².

strike: The direction of a horizontal line in the plane of an inclined stratum, joint or other structural plane. see also ‘full dip’.

strip mining: Opencast mining by the excavation of defined sections or strips.

stripping: 1 The removal of overburden. 2 The loss of bitumen from aggregate exposed at a road surface which leads to a breakdown of the bond and the loosening of particles exposed to traffic.

stripping ratio: The ratio of the overburden removed to the mineral mined in an opencast operation.

stroke: The distance between the extreme positions of an oscillating or vibrating motion, ie the stroke is equal to twice the amplitude.

struck capacity: The capacity of an earthmover vehicle when the load is level with the sides of the body.

structure plan: The strategic framework for a local authority covering housing, industry, routeways and where appropriate, minerals.

strut: A light structural member which sustains an axial compressive load.

sub-base: One or more layers of material situated between the roadbase and the sub-grade.

sub-grade: The upper part of the soil, natural or constructed, which supports the loads transmitted by the overlying pavement.

sub-grade drilling: The continuation of blastholes for a short distance below the quarry floor or bench level in order that, after blasting, these levels may be maintained.

submersible pump: A centrifugal pump which may be driven by electricity or compressed air and may be totally submerged in water.

subsoil: The weathered soil or rock immediately below the topsoil.

substation: Plant and equipment for the transformation and control of electrical energy housed in one enclosure.

substructure: The part of the structure which is below ground, in particular the foundations and piers of a bridge.

suction dredger: A vessel from which the suction pipe of a centrifugal pump is lowered into the deposit and by means of which sand and gravel is raised and either deposited in the vessel itself or delivered to barges for transhipment to a shore-based treatment plant or pumped direct by pipeline to the plant.

suction head: The height to which a pump can raise water on its suction side, measured from the water level in the sump. Theoretically this is approximately 10m, but in practice pumps should be sited so that it is kept to a minimum and it should not be more than about 6m.

suction valve: A check or non-return valve attached to the lower end of a pump suction pipe which allows water to flow only in an upward direction.

suction-cutter dredge: A suction dredge with a rotary cutter, mounted in front of the suction pipe, which breaks up the material to be pumped to the surface.

sump: A pit in which water collects before being pumped out. The pump suction is suspended in the sump.

supercharging: The supply of air to an internal-combustion engine at a pressure greater than atmospheric resulting in, at a given speed, more torque and increased power output.

super-elevation: The amount by which the outside of a curved track is raised above the inside to provide some of the cornering force required to hold a moving vehicle in the turn and so reduce the tendency for the tyres to lose adhesion outwards.

super quarry: A high output unit capable of producing several million tonnes a year.

superficial deposits: The most recent deposits, generally unconsolidated (eg peat, sand, gravel etc) lying above the rockhead.

superstructure: The visible part of a structure, ie that part above the substructure.

surface dressing: The renewal of the surface of a minor road by the spreading of chippings on to a film of bitumen coating the previous surface.

surface treatment: A general term for work carried out to alter the qualities of a wearing course.

surfacing: A surface course or a combination of a surface course and a binder course.

surge bin/hopper: A receptacle capable of receiving and re-dispensing tonnages of material, thus steadying any fluctuations in flow.

swash-plate: A circular plate mounted at an angle to the centre-line of the drive shaft of a pump or hydraulic motor. The cylinders are mounted axially concentric with the shaft and, as the swash-plate rotates, its movement is transmitted through connecting rods to the pistons which move in and out of the cylinders, creating a flow of oil.

swell factor: The ratio of the volume of material when broken to that when in situ.; may also be expressed as the reciprocal of this number.

swing jaw: The moving member of a jaw crusher.

switchgear: Electrical apparatus the function of which is to open and close circuits and may also include devices which provide protection for apparatus connected to an electrical supply.

symbols: Conventional electrical circuit and hydraulic system symbols are given in the appendices.

synchromesh gear: A gear in which the speeds of the driving and driven gear wheels are automatically synchronized by small cone clutches before they engage, thus avoiding shock and noise when gears are changed.

synchronous motor: A constant-speed motor, the speed being dependent on the frequency of the ac supply and the number of poles for which it is designed. Main applications are for driving machinery where continuous running is required and where it can be operated at a leading power factor to give power-factor improvement.

syncline: A trough-like fold in stratified rocks.