The Aggregates & Recycling Information Network

Glossary: S

  • 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.

  • Safety Fuse

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

  • SAGA

    abbr. Sand and Gravel Association

    The former trade federation for sand and gravel producers now amalgamated with BACMI as QPA.

    In 2009, QPA joined forces with the British Cement Association and The Concrete Centre to form the Mineral Products Association (MPA).

  • Sampling

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


    abbr. Silica and Moulding Sand Association

    The trade federation for producers of special sands.

  • Sand Casting

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

  • 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

    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. 

    Also: 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 Plate

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

  • 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.

    Also: helical conveyor 

  • Screw Shackle

    A long nut screwed internally with a right-handed thread at one end and a left-handed thread at the other. It is used to connect two rods which are to be joined together so that when the nut is tightened it draws the ends together, providing a means of adjusting the total length. 

    Also: turnbuckle

  • 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.

  • SDT

    abbr. 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.

  • 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

    The ratio of the magnetic flux-linkage of an electric circuit and a current. Self-inductance refers to inductance in which the current is that of the circuit itself and mutual-inductance where the linkage results from the current in another circuit.

    Symbol: H

    Unit: Henry

    Also: inductance and mutual 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.

  • SHE

    abbr. Safety, Health and Environment

  • 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.

  • 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.

    See also: Nonel system 

  • 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.

  • 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.

  • 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.

  • 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.

  • 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 also: 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.

  • 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.

  • Slaked Lime

    Product formed when quicklime is slaked with water.

  • Sledging Rolls

    Sledging rolls employ a combination of impact, shear and pressure. They have at intervals round the rolls, rows of teeth of varying length which grip the rock and feed it into the crushing chamber, also acting as picks to break the larger lumps; the optimum type of feed is stratified friable rock.

    See also: 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

    An induction motor the ends of the rotor windings of which are connected to slip-rings through which external resistance may be added to the rotor circuit for starting purposes. Used for duties in which on-load starting is required. 

    Also: wound-rotor motor

  • 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

    The ratio of the density of the substance to the density of water. Specific gravity is now called relative density and has no units. 

    Also: 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 also: 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.

    Also: chambering

  • Sprocket

    A toothed wheel used for chain drives.

  • 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.

    Also: cage motor

  • SRV

    abbr. skid resistance value

    This is the value obtained from the actual road surface, measured using the Portable Skid Resistance Tester. The resistance to skidding of a road surface, i.e. its SRV, is dependent on the Polished Stone Value (PSV) of the aggregate in the surface course asphalt and the macrotexture (roughness) of the surface course material.

  • 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.

  • 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.

  • 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.

  • Stratification

    Layering in sedimentary rocks due to changes in rate of deposition or nature of sediment.

  • 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 also: cube test

  • Strengths Of Explosives

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

    See also: 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-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 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
    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.

  • Super Quarry

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

  • 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.

  • 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.

  • 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.

  • 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.

  • Syenite

    Intermediate plutonic rock consisting mainly of alkali feldspar with plagioclase, hornblende, biotite or augite.

  • 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.

  • System

    Series of rocks formed during certain periods of geological time.