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| Pad |
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Impermeable foundation used as a base for ore during heap leaching.
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| Parts per million (ppm) |
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1 milligram per kilogram = 1ppm = 1 pound per million pounds.
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| Pascal (Pa) |
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A unit of pressure or stress equal to one newton per square metre.
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| Peat |
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Partially decayed plant material found in swamps and bogs. One of the earliest stages of coal formation.
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| Percussion drill |
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A drill that delivers its energy through a pounding or hammering action.
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| pH |
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The degree of acidity or alkalinity of a solution. pH levels below 7 are acidic and above 7 are alkaline.
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| Photocell |
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Device used to detect the presence of an object. A photocell is composed of a transmitter, which transmits an infrared signal to a receiver or reflector.
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| Pilot pressure |
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Auxiliary pressure used to actuate or control hydraulic components.
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| Pilot valve |
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An auxiliary valve used to control the operation of another valve. The controlling stage of a 2-stage valve.
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| Piston |
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A cylindrically shaped part which fits within a cylinder and transmits or receives motion by means of a connecting rod.
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| Pitch |
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The relative angle of slope or dip of an ore deposit.
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| Pitchblende |
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An important uranium ore mineral, containing a high percentage of uranium oxide.
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| Placer |
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Alluvial deposit of sand and gravel containing valuable metals such as gold.
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| PLC |
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Programmable logic controllers. Industrial computer with I/O capability, which programs in ladder-relay logic.
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| Plumb |
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Straight up and down, perfectly vertical.
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| Plunger |
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A cylindrically shaped part which has only one diameter and is used to transmit thrust. A ram.
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| Polishing pond |
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The last settling ponds through which mill effluent flows before being discharged into the natural environment.
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| Polymetallic |
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Complex ores containing profitable amounts of more than one valuable mineral.
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| Poppet |
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That part of certain valves which prevents flow when it closes against a seat.
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| Port |
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An internal or external terminus of a passage in a component.
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| Positive displacement |
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A characteristic of a pump or motor which has the inlet positively sealed from the outlet so that fluid cannot recirculate in the component.
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| Potentiometer |
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A control element in the servo system which measures and controls electrical potential.
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| Pound (lb) |
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A unit of weight equal to 16 ounces (0.45 kilograms).
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| Power |
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Work per unit of time. Measured in horsepower (hp) or watts (W).
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| Power pack |
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An integral power supply unit usually containing a pump, reservoir, relief valve and directional control.
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| Pre-Stripping |
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Removing the waste rock (overburden) to gain access to an ore body below.
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| Precharge pressure |
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The pressure of compressed gas in an accumulator prior to the admission of liquid.
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| Precipitate |
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Material that settles from a liquid solution when a particular substance is added to the solute.
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| Preparation plant |
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A plant where coal is cleaned, sized, and prepared for market.
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| Pressure |
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Force per unit area. Usually measured in pounds per square inch (PSI) or kilopascals (kPa). A kilopascal is equal to 1000 newtons per square metre or 0.0102 kg/sq cm (0.145 lb/sq in).
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| Pressure burst |
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A seismic event whereby there is a sudden release of energy in a mine, much like a mini-earthquake.
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| Pressure drop |
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The difference in pressure between any two points of a system or a component.
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| Pressure line |
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The line carrying the fluid from the pump outlet to the pressurized port of the actuator.
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| Pressure override |
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The difference between the cracking pressure of a valve and the pressure reached when the valve is passing full flow.
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| Pressure plate |
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A side plate in a vane pump or motor cartridge on the pressure port side.
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| Pressure reducing valve |
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A valve which limits the maximum pressure at its outlet regardless of the inlet pressure.
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| Pressure switch |
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1. An electric switch operated by fluid pressure.
2. Switches that read the available pressure in air and hydraulic lines. These switches are
often used as a safety feature, to prevent equipment from operating when there is not enough
air pressure or hydraulic fluid pressure.
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| Primary deposits |
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Ore minerals deposited during the original period or periods of metallization as opposed to those deposited as a result of alteration or weathering.
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| Probable reserves |
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Valuable mineralization that has been not sampled enough to accurately estimate the tonnage and grade.
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| Proportional flow |
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In a filter, the condition where part of the flow passes through the filter element in proportion to pressure drop.
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| Prospecting |
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The search for valuable mineral deposits.
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| Proven reserves |
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Reserves that have been sampled extensively and in sufficient detail to render an accurate estimation of grade and tonnage.
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| Proximate analysis |
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A physical test of the constitution of coal that is not precise, but very useful for determining the commercial value.
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| Proximity switch |
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Photoelectric switches that are triggered as a piece passes near them. Proximity switches are used to detect the presence or absence of material.
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| PSI |
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Pounds per square inch.
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| Pulp |
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Pulverized or ground ore in solution.
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| Pump |
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A device which converts mechanical force and motion into hydraulic fluid power.
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