The Aggregates & Recycling Information Network

Glossary: I

  • Idle Component

    The component of the phasor current or voltage which is in quadrature with the voltage or current. 

    Also: reactive component and wattless component

  • IDO

    abbr. Interim Development Order

    Mineral working permissions granted between 1943-48. Sites operating under an IDO permission must now register with the MPA.

  • Igneous

    Rock formed by the cooling and consolidation of magma, the fluid melt of rock material.

  • Igniter Cord

    A cord which passes an intense flame along its length at a uniform rate to light safety fuses in succession. Usually used where there are more than six safety fuses to be lit; a shotfirer should not attempt to ignite more that six points at anyone time.

  • Illuminance

    The luminous flux density at a surface, ie the luminous flux on a surface divided by the area of the element.

    Symbol: E

    Unit: lux (lx)

  • Impact Load

    The dynamic forces imposed on a structure by the motion of the live load.

  • Impact Plates

    The wear plates attached to the inside of the chamber of an impact crusher and against which rocks are projected by the blow bars on the rotor.

  • Impedance Triangle

    A right-angled phasor triangle the hypotenuse of which represents impedance and the two other sides resistance and reactance.

  • Impeller

    The rotating member of a centrifugal pump or of a compressor.

  • In-situ Recycling

    Procedures that use specialist plant to pulverise and stabilise existing road materials, in-place, at ambient or elevated temperatures, with the addition of bitumen or hydraulic binders.

  • 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: mutual inductance and self-inductance

  • Induction Motor

    An ac motor in which the current in the stator windings produces a rotating flux which induces a current in the conductors of the rotor and a magnetic field around them. The two fields react with one another to produce torque and movement of the rotor in the same direction as that of the stator field.

  • Inductive Circuit

    A circuit having self-inductance that has an appreciable effect compared with its resistance.

  • Inductor

    A coil the primary characteristic of which is the property of inductance.

    Also: choke

  • Inert Waste

    The Landfill (England and Wales) Regulations 2002 and the Waste Management Licensing Amendment (Scotland) Regulations 2003 provide the following definition of inert waste: "Waste is considered inert if:

    1. It does not undergo any significant physical, chemical or biological transformations;
    2. It does not dissolve, burn or otherwise physically or chemically react, biodegrade or adversely affect other matter with which it comes into contact in a way likely to give rise to environmental pollution or harm to human health; and
    3. Its total leachability and pollutant content and the ecotoxicity of its leachate are insignificant and, in particular, do not endanger the quality of any surface water or groundwater."
  • Inertia

    The property by which a body resists a change in its state of motion.

  • Initiation

    In blasting, the method used to fire the charge, or the instant at which the explosion begins.

  • Inspector

    A Crown official with statutory powers of inspection, investigation, inquiry and enforcement of safety law.

    Also: HM Inspector

  • Intercooler

    A device for cooling air between one stage of compression and the next.

  • Interim Development Order

    Mineral working permissions granted between 1943-48. Sites operating under an IDO permission must now register with the MPA.

    abbr. IDO

  • Intermediate Rock

    Igneous rock containing more than 52% and less than 66% silica.

  • Internal-combustion Engine

    An engine in which the combustion of the fuel takes place within the cylinder, and the products of combustion result in increased gas pressure which causes the piston to be driven down the cylinder.

  • Interpolation

    The estimation of the value of a particular point on a graph from values on either side of the point by assuming the line of the graph is smooth.

  • Intrusion

    A mass of igneous rock which, while molten, was forced into or between other rocks.

  • Intrusive

    Describes igneous bodies of varying size and structure injected into pre-existing rocks of the earth’s crust.

  • Inverse Initiation

    A method of blasting in which the primer cartridge is placed at the end of the explosive charge farthest from the entrance to the blasthole and the detonator is placed at the inner end of the primer cartridge.

    Also: bottom initiation

  • Inverse Square Law

    The intensity of a field of radiation is inversely proportional to the square of the distance from the source. This applies, for example, to the intensity of sound at a distance from a source.

  • Iron Loss

    In an alternating current system, the eddy current and hysteresis losses developed as heat in the ferromagnetic core of a machine or transformer.

    Also: core loss

  • ISO 9001

    An internationally recognised quality standard applied to quality management systems produced by the International Organisation for Standardisation (ISO). The standard is relevant to all sectors of industry and is based on the principles of customer satisfaction, continual improvement and development of a process-based quality monitoring system.

  • Isolator

    A switch used for disconnecting a circuit from the supply under no-load conditions.

  • Isopachyte, Or Isopach

    A line drawn on a map through points of equal thickness of a specified rock.

  • Isothermal

    A process which occurs at constant temperature.

  • Issued Capital

    The proportion of the authorized capital which has been issued to shareholders.