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| Radon survey |
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Geochemical survey technique which detects traces of radon gas, a product of radioactivity.
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| Ram |
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A single-acting cylinder with a single diameter plunger rather than a piston and rod. The plunger in a ram-type cylinder.
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| Rank |
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The classification of coal by degree of hardness, moisture and heat content.
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| Rare earth elements |
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Scarce minerals such as scandium and ytrium.
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| Receiver |
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Head of a scanner that monitors the infrared signals transmitted by the transmitter head.
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| Reciprocation |
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Back-and-forth straight line motion or oscillation.
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| Reclamation |
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The process of returning the land to another productive use or restoring the land to its approximate original appearance after mining has been completed.
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| Recovery |
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Percentage of valuable metal in the ore that is recovered by metallurgical extraction.
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| Recovery (product) |
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An expression of the amount of product (nominal or actual) that can be manufactured from a given input of raw material.
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| Refining |
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Extracting and purifying metals and minerals.
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| Refractory ore |
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Ore that resists the action of chemical reagents in the normal treatment processes.
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| Regenerative circuit |
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A piping arrangement for a differential type cylinder in which discharge fluid from the rod end combines with pump delivery to be directed into the head end.
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| Relief valve |
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A pressure operated valve which by-passes pump delivery to the reservoir, limiting system pressure to a predetermined maximum value.
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| Replenish |
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To add fluid to maintain a full hydraulic system.
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| Resistivity survey |
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Geophysical survey technique used to measure the resistance of a rock formation to an electric current.
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| Resolution |
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The smallest unit used for taking measurements from a scanner or the encoder.
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| Restriction |
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A reduced cross-sectional area in a line or passage which produces a pressure drop.
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| Retort |
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Used to separate or vaporize off mercury from gold.
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| Return line |
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A line used to carry exhaust fluid from the actuator back to sump.
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| Reverberatory furnace |
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A long, flat furnace used to slag gangue minerals and produce a matte.
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| Reversing valve |
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A four-way directional valve used to reverse a double-acting cylinder or reversible motor.
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| Ripper |
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Coal extraction machine that tears the coal from the face.
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| Roast |
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Heating an ore to drive off volatile substances or oxidize the ore.
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| Rock mechanics |
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The study of the mechanical properties of rocks. Includes stress conditions around mine openings and the ability of rocks and underground structures to support these stresses.
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| Rockburst |
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A sudden failure of walls or pillars in a mine, caused by the weight or pressure of the surrounding rocks.
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| Rod mill |
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Rotating steel cylinder that uses steel rods as a means of grinding ore.
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| Roller |
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A cylindrical body movable about its longitudinal axis.
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| Room and pillar mining |
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Underground coal mining method in which approximately half of the coal is left in place to support the roof of the active mining area
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| Rotary actuator |
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A device for converting hydraulic energy into rotary motion - a hydraulic motor.
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| Rotary drill |
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A machine that drills holes by rotating a rigid, tubular procession of drill rods to which is attached a bit.
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| Round |
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Planned pattern of drill holes fired in sequence in tunneling, shaft sinking, or stopping.
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| RPM |
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Revolutions per minute.
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| RTD |
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A temperature measuring device that measures the change in electrical resistance to determine temperature (resistive thermal device).
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| Run of mine (ROM) |
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Material from a mine that has not been crushed or screened.
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| Run of quarry (ROQ) |
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Material from a quarry that has not been crushed or screened.
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| Rung |
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An element of the PLC ladder logic program. Each rung looks at input signals and turns output signals on or off. The program runs by scanning the ladder logic, testing the input points and the instructions on each rung, and turning the output points on or off.
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