Rock is extracted from the ground in the quarrying process to produce 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 screening:
Aggregate is screened into the sizes required for immediate use, or for further processing within the quarrying production line.

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

Any of various flammable mixtures of hydrocarbons and other substances, occurring naturally or obtained by distillation from coal or petroleum, that are a component of asphalt and tar and are used for surfacing roads and for waterproofing.

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.

To break, pound, or grind, stone or ore, into small fragments or powder. Crushing can be done in three or four stages, primary (first stage), secondary (second stage), tertiary (third stage), and in some quarries a quaternary (fourth stage).

Feed box:
A box, usually mounted on the feed end of a screen, used to reduce the velocity of the feed and to distribute it across the full width of the screen.

Particles finer than 63µm.

Coalescence of minute particles into floccules to accelerate settlement as part of dewatering or thickening of a pulp. Chemicals are used to promote adhesion.

Glass recycling:
Glass recycling is the process of turning waste glass into usable products. This includes separating different colours (usually transparent, green and brown) of glass.

Granular material in the size range 2mm to 60mm, generally arising in the form of sand and gravel deposits allied to river/ water activity


  1. Term which, when applied to describe dispersions of small solid particles in air or other gas, refers to those particles which are larger than 76µm.
  2. Small hard fragments of mineral aggregate for application to a road surface.

Sandstone with angular, usually coarse grains.

A sturdily built type of screen constructed of parallel tapered steel bars held apart by distance pieces.

Hydrated calcium sulphate, CaSO4.2H2O, associated with other evaporite minerals in extensive beds. Used in the manufacture of plaster-board, Portland cement, fertilizer etc.

Gyratory crusher:
Usually either performs in a secondary or tertiary function.
A compression crusher consisting of a moving member, known as the head, in the form of an erect truncated cone rotating eccentrically within the fixed member (the outer shell), which is in the form of a frustum of an inverted cone.

abbr. incinerator bottom ash. 
The residual solid material from the combustion process in municipal solid waste incineration facilities.

Impact crushers:
Crushers in which the rock is fragmented by kinetic energy imparted into the feed material by a rotating mass (the rotor), which projects the material against a fixed surface, causing it to shatter.

Jaw crusher:
Usually performs the primary crushing, consists of a heavy metal plate which moves backwards and forwards against a fixed plate which are referred to as the jaws.
A compression crushing machine consisting of a fixed crushing face and a mobile face which moves so as to increase and decrease alternately the gap between the two faces.

Coal of low rank with high inherent moisture and volatile matter.

A long water tank set at a slope, in which one or two shafts, or logs, fitted with paddles set helically rotate. The feed is introduced at the lower end of the tank, the paddles break it up and subject it to a tumbling action; dirty water and fines are discharged at the lower end and washed aggregate at the upper end. These washers are used where there is conglomerate or a high proportion of clay among the gravel.

Materials Recovery Facility:
In the waste management industry, a Materials Recovery Facility (MRF — pronounced “murf”) is a specialised plant that receives, separates and prepares recyclable materials for marketing to end-user manufacturers. Generally, there are two types – clean and dirty MRF’s. Clean referring to single source waste and dirty referring to mixed-waste.

Picking station:
Picking stations are used when manual sorting of the feedstock is required. Manual sorting may be required when unwanted materials cannot be reliably or efficiently removed by other methods. Picking stations are horizontal conveyor belts configured to allow operatives to remove unwanted items by hand.

Range of resins, both thermoplastic and thermosetting, used in the lining of pipes, vessels and other parts subject to wear, and in the manufacture of screen panels.

Primary Crushing:
The crushing of run-of-quarry stone from pieces of up to 1.5m across to rocks of up to 300-400mm.

Resonance screen:
A screen with a period of oscillation at or very close to the natural period of oscillation of the mass of the screen on its resilient mounting.

A naturally occurring granular material in the size range 0.06mm to 2mm, often containing a high proportion of quartz.

Generally to remove inferior top rock and clay from the main feed to a mineral-processing plant.

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

Aggregate is screened into the sizes required for immediate use, or for further processing.

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

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

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.

A suspension of mineral particles in water.

Tertiary crushing:
The third stage of size reduction mineral (less than 20mm or even 10mm).

Large circular tank in which solids settle slowly and form a slurry which is continuously removed from below while fairly clear water overflows. Also called a clarifier.

A rotary screen for sizing aggregate, coal or ore. It consists of a cylindrical shell of perforated plate or wire cloth, mounted on a central shaft inclined at a small angle to the horizontal. It may also be fitted to the discharge end of a washing barrel or scrubber.

Vibratory Feeders:
A machine that automatically provides a supply of material through a vibrating deck.

Wash plant:
Complete plant which is used in the production process to remove clay and silt from sand and gravel. Provides the means to producing higher aggregate specifications which are increasingly necessary due to shortages of natural sand and gravel.

Washing Barrel:
An aggregate-washing device consisting of a rotating cylinder fitted internally with lifters which lift and move the aggregate along the barrel either with (uniflow) or against (contraflow) the wash water.

Washing Screen:
An inclined vibratory screen with spray bars fixed above the deck. High-pressure water jets remove dust, loam and clay from the feed and assist in providing a tumbling action to give improved cleaning.

A device for weighing a load carried by road or rail wagons. It is a very heavy duty weighing scale which can weigh the vehicle both empty and loaded and thus calculate the load carried by the vehicle.

Wet Screening:
The addition of water to the feed or the spraying of water on to the screen deck in order to improve screening efficiency and increase capacity.

Waste & Resources Action Programme 
A not-for-profit company, backed by government funding, which helps individuals, businesses and local authorities to reduce waste and recycle more, making better use of resources and helping to tackle climate change.

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