PE Mining key terms

An underground method in which ore is extracted in rooms while pillars of unmined rock are left to support the roof; commonly used in flat-lying, tabular deposits.

A high-extraction underground coal method where a long face is mined and the roof is allowed to collapse behind movable supports as the face advances.

Surface mining that removes overburden and ore in successive horizontal benches to form a large, expanding pit, used for relatively shallow, bulk-tonnage deposits.

A mass-mining underground method in which undercutting causes a large block of ore to collapse under its own weight and be drawn from drawpoints beneath.

The minimum grade of material that justifies mining and processing it economically; material below this grade is treated as waste or stockpiled.

The ratio of waste material that must be removed to ore mined, usually expressed as tonnes of waste per tonne of ore or cubic metres per cubic metre.

The underground excavation from which ore is extracted in controlled blasts and draws; its design must balance ore recovery with wall and roof stability.

A geotechnical classification that combines rock strength, joint spacing, groundwater and other factors to produce a numerical score used for support design.

A rock mass classification system using six parameters (RQD, joint sets, roughness, alteration, water and stress) to calculate a Q value for tunnel support recommendations.

A tensioned steel bar or cable installed into a drill hole to reinforce and pin rock masses, helping to prevent loosening and falls in underground openings.

Concrete or mortar sprayed pneumatically onto rock surfaces to provide immediate surface support, seal loose ground, and help prevent small rock falls.

The process of sizing pillars of unmined rock so they can carry overburden and abutment loads with an adequate safety factor while maximizing ore recovery.

The assessment and control of the tendency of pit walls or natural slopes to fail, governed by rock structure, groundwater, slope angle and blasting effects.

A sudden, violent release of stored strain energy in a highly stressed rock mass that can eject rock into an excavation and injure workers or damage equipment.

The distance from a blast hole to the nearest free face, measured perpendicular to the hole; it strongly influences fragmentation and the risk of overbreak or flyrock.

Inert material such as crushed rock or sand placed in the top of a blast hole above the explosive to confine the detonation gases and improve blasting efficiency.

Ammonium nitrate fuel oil, a low-cost bulk explosive widely used in mining; it is not water-resistant and requires a booster and detonator to initiate.

A water-resistant explosive consisting of oxidizer droplets dispersed in a fuel phase, often used in wet holes and bulk loading systems in underground and surface mines.

The amount of explosive used per unit of rock broken, commonly expressed as kilograms of explosive per tonne or per cubic metre of rock.

A blasting device that initiates a charge after a specified time delay, allowing holes to fire in sequence to improve fragmentation and control vibration.

Rock fragments thrown beyond the intended blast area by excessive explosive energy; a major safety hazard controlled by proper burden, stemming and blast design.

The primary ventilation fan or fans that move air through the entire mine circuit, usually located on surface and capable of reversing airflow in an emergency.

Secondary ventilation used to supply air to dead-end headings and workings, typically through ducting and small fans because the main airflow does not reach there.

The controlled removal of methane from coal seams or surrounding strata via boreholes and pipelines before or during mining to reduce explosion risk in the mine atmosphere.

Methods such as water sprays, wetting agents, ventilation and sealing used to reduce airborne dust at its source and protect workers from respirable dust exposure.

The formation of acidic, metal-laden water when sulfide minerals, especially pyrite, are exposed to air and water in mine workings, waste rock or tailings.

Self-heating and ignition of reactive materials such as coal or sulfide ores without an external ignition source, often caused by oxidation and poor ventilation of broken material.

A machine that reduces run-of-mine ore to a smaller size by compression, impact or attrition, preparing it for grinding or further processing.

A rotating cylindrical mill charged with steel balls, rods or ore pebbles that reduces crushed ore to fine particles, often in a slurry, to liberate valuable minerals.

A separation process in which valuable mineral particles are made hydrophobic and attach to air bubbles in a froth, while gangue particles remain in the slurry.

A large settling tank that removes water from a mineral slurry by gravity, producing a concentrated underflow and a clarified overflow for reuse or discharge.

A process where crushed ore is stacked on a lined pad and irrigated with a leaching solution that dissolves metals, which are recovered from the collected pregnant solution.

A mining cost metric that includes cash operating costs, sustaining capital, royalties and exploration, giving a fuller picture of the cost of maintaining production.

The sum of expected future cash flows discounted to today's value at a chosen rate; used to compare project economics and investment decisions.

Items worn by workers such as helmets, gloves, respirators, hearing protection and high-visibility clothing to reduce exposure to workplace hazards.

The continuous or periodic measurement of gases such as methane, carbon monoxide, oxygen and hydrogen sulfide in mine air to detect hazards and trigger alarms.