| Pa (Pascals) |
| Pascals is a measure of pressure and is equivalent to Newtons per square metre (N/m2). |
| Particle size |
| Sand and gravel are defined on the basis of particle size rather than composition. Fines (material < 0.063 mm) Sand (0.063 2 mm) Gravel (2 4 mm (geology), coarse sand to large cobbles (civil engineering)) Cobbles (64-256 mm). Boulders > 256 mm |
| Particulates |
| Generic term used interchangeably with ?dust? to describe fine solid matter capable of entering atmospheric suspension. |
| Peak Particle Velocity (PPV) |
| When a vibration is measured, the point at which the measurement takes place can be considered to have a ?particle velocity?. This particle vibration will take place in three dimensions and will usually end up back where it started. This type of particle velocity must not be confused with the velocity with which the wave moves through the rock. The Peak Particle Velocity is the maximum velocity which is recorded during a particular event and can refer to a particular orientation (vertical or horizontal) or to the maximum. |
| Pegging |
| The obstruction of a sizing screen by single fragments which become wedged in the apertures |
| Perched Water Table |
| These are small water tables which can form above the main water table and are caused, for example, by layers of clay that prevent water moving down to the main water table.
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| Permeable |
| A rock is permeable if water can pass through it.
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| Piezometer |
| An open borehole or standpipe which allows water to rise and fall freely within it. It can be used to test the hydraulic head.
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| Planning |
| The laying out of a proposal for a mineral operation for submission to the local Mineral Planning Authority. |
| Planning permission |
| Formal approval sought from a local government Mineral Planning Authority. It is usually granted with conditions, allowing a proposed development to proceed. Permission may be sought in principle through outline plans, or be sought in detail through full plans. |
| Planning Policy Guidance (PPG) |
| Planning Policy Guidance notes set out the UK Government's national policies on different aspects of planning. They are being replaced by Planning Policy Statements. |
| Planning Policy Statements (PPS) |
| Planning Policy Statements set out the UK Government's national policies on different aspects of planning. They are gradually replacing the Planning Policy Guidance notes. |
| Plate press filters |
| Mechanical dewatering devices that hydraulically compress a filter pack comprising a series of diaphragms incorporating a porous cloth. A slurry is fed into the diaphragms under pressure. The filter pack is then compressed hydraulically expelling excess water through the cloth and leaving the desired solid material. |
| PM10 |
| Particles less than 10 micrometres in diameter, including both fine and coarse dust particles. These particles pose the greatest health concern because they can pass through the nose and throat and get into the lungs. |
| Pneumoconiosis |
| Disabling lung disease caused by the inhalation of fine dust particles leading to fibrosis. This was formerly more prevalent in the mining industry before dust suppression and protective equipment became mandatory. It is particularly associated with underground coal mining (black lung) and with drilling and processing operations involving quartz-rich rock (pneumosilicosis). |
| Point Source |
| A dust emission source focused at a discrete physical location, such as a mineral crushing unit or a mineral excavator. |
| Polished Stone Value (PSV) |
| The Polished Stone Value of aggregate is measured using a standardised test (BS EN 13043: Aggregates for bituminous mixtures and surface treatments). This gives a measure of the resistance of the aggregate to the polishing action of vehicle tyres under conditions similar to those occurring on a road surface. |
| Porosity |
| A rock is said to be porous if it possesses cavities between the mineral grains making up the rock which can contain liquid.
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| PPG |
| See Planning Policy Guidance. |
| PPS |
| See Planning Policy Statement. |
| PPV |
| See Peak Particle Velocity. |
| Preferred Areas |
| These are areas of known mineral resources where planning permission might resonably be anticipated. |
| Prehistoric |
| A catch-all term for the pre-Roman periods |
| Pre-trigger Memory |
| This is the facility which allows blast vibration monitors to capture ground and air vibrations in the second or so before the machine is triggered into recording mode. In this way, none of the signal is lost and full analysis can be carried out. |
| Preventative |
| Deliberate action or methodology to avoid the incidence of a deleterious occurrence. For example, accident prevention through identification of potentially hazardous situations and training to avoid them, or preventative maintenance to replace wearing parts after set hours worked rather than wait for failure. |
| Primary Blast |
| The breaking out of stone from its natural state using explosives. |
| Primary Crusher |
| The primary crusher is the initial crushing operation on run of mine rock to reduce its size for further processing. It generally reduces the maximum size of rocks from under 1.5 m to under 0.3 m. |
| Primary Crushing |
| The first crushing of stone before washing, sorting and further crushing from pieces up to 1.5 metres across to rocks up to 300-400mm. |
| Primary fragmentation |
| The breaking of solid rock into smaller fragments by the initial blast in a mine or quarry so that the bulk of the material is small enough to transport. |
| Probability screen |
| Also known as a Morgensen sizer this device consists of several steeply inclined vibrating screen decks. The coarse oversize is removed early, reducing wear and fines production on the lower decks. It also has a high throughput and low energy requirement. |
| Processing |
| Few rocks can be used as dug and processing prepares the extracted material to be used as a construction mineral. It includes screening to remove clays and fines, and crushing and screening to produce material with specified size grades, minimise fines content etc. |
| Product |
| Output from the crusher, the desired size-fraction. |
| Production plant |
| Building or area containing the equipment used to process material in a quarry. |
| Progressive restoration |
| Restoration which takes place before the end of the site in areas no longer required in the mineral operation. |
| Proposals Map |
| This illustrates in map form the policies and proposals in the development plan document. |
| Psuedo Resultant |
| When the vector sum is taken of the maximum of each of the vertical, longitudinal and transverse records rather than of each point, then the answer will be greater than the true Resultant PPV and can be known as the Psuedo Resultant. |
| PSV |
| The Polished Stone Value of aggregate is measured using a standardised test (BS812 Part1 14:1989). This gives a measure of the resistance of the aggregate to the polishing action of vehicle tyres under conditions similar to those occurring on a road surface. |