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Absolute:
A measure having as its zero point or base the complete absence of the entity being measured.

Absolute pressure:
The pressure above zero absolute, i.e., the sum of atmospheric and gauge pressure.  In vacuum related work it is usually expressed in millimeters, or inches, of mercury.

Acceptance sampling:
A statistical quality control method that seeks to determine the quality of a product by sampling a small portion of it.  It does not assure that 100 percent of the product is acceptable, but reduces the likelihood of acceptance of a defective product.

Accumulator:
A container in which fluid (generally nitrogen) is stored under pressure as a source of fluid power.

Acidic rocks:
Most often refers to an igneous rock carrying a high proportion of silica (>65%).

Acid mine drainage:
Acidic run off water from waste dump and mill tailings ponds containing sulphide minerals. Acidity can promote the solubilization of heavy metal contaminants and must be treated before release into the natural environment.

Acid mine water:
Natural seepage of moisture through the ground that reacts with iron pyrites which eventually accumulates within a mine as water containing free sulphuric acid.

Acid rock drainage:
Acidic run off water from waste dump and mill tailings ponds containing sulphide minerals. Acidity can promote the solubilization of heavy metal contaminants and must be treated before release into the natural environment.

Acre (a):
A unit of area used in English-speaking countries, equal to 4,840 square yards (0.405 hectares).

Active workings:
Areas inside a mine where miners actively work or travel. These areas are well ventilated and undergo continuous safety and health inspections.

Actuator:
A device for converting pneumatic or hydraulic energy into mechanical energy.  A motor or cylinder.

Adhesive:
A substance capable of holding materials together by surface attachment. It is a general term and includes cements, mucilage, and paste, as well as glue.

Adit:
A type of entrance into a hill (mine) which is horizontal or nearly horizontal.

Aerial Magnetometer:
An instrument (magnetometer) housed in an aircraft or towed behind it which measures the earth's magnetic field.

Aerial Survey:
A survey made from an aircraft with the purpose of taking photographs or measuring magnetic properties, radioactivity, etc.

Aeromagnetic Survey:
A geophysical survey method to measure the strength of the earth magnetic field using a magnetometer aboard or towed behind an aircraft.

After damp:
The gas resulting from an explosion of coal dust or fire damp in a mine. Nearly always contains dangerous amounts of carbon monoxide.

Ag:
Symbol for the element Silver.

Agglomeration:
A process used to bind or cement crushed/ground rock particles together into larger pieces like pellets, which are easier to handle.

Alloy:
A mixture of two or more pure metals. Creates a metal with new qualities and properties.

Alluvial gold:
Small particles (gold dust) or even nuggets, which are usually found on riverbeds or close to the surface when erosion or weathering has exposed deposits.

Amalgamation:
The process of extraction alluvial gold using mercury to form an amalgan.

Amplifier:
A device for amplifying the error signal sufficiently to cause actuation of the stroke control.  Several types of servo amplifiers are used at the present time: electronic (DC, AC, phase sensitive, and magnetic) and mechanical.

Amplitude of sound:
The loudness of a sound.

Analog:
A continuous range of numbers or values.

ANFO:
Acronym for ammonium nitrate and fuel oil, a mixture used as a blasting agent in many mines.

Angle of repose:
The maximum angle measured in degrees at which a granular material retains its slope.

Anisotropic:
Exhibiting different properties when measured along different axes.  In general, fibrous materials such as wood are anisotropic.

Annular area:
A ring shaped area - often refers to the net effective area of the rod side of a cylinder piston, i.e., the piston area minus the cross-sectional area of the rod.

Anode:
A rectangular metal plate used in the electrolytic process of mineral refining.

Anomaly:
A departure from normal conditions which could indicate the presence of mineralization in the underlying bedrock.

Assay:
The process of testing samples of ores or minerals to determine the amount and purity of valuable metals contained within.

Atmospheric pressure:
Pressure exerted by the atmosphere at any specific location.  (Sea level pressure is approximately 14.7 pounds per square inch absolute.)

Attrition:
The size reduction or loss of materials through friction and abrasion.

Au:
Symbol for the element Gold.

Auger:
Rotating screw device used to bore, break and transport the material. Often used in coal mining with horizontal or slightly pitched seams.

Autoclave:
Cylindrical vessel used to subject materials to high pressure and temperature. Used at mines using hydrometallurgy mineral processing techniques.

Autogenous grinding:
Autogenous grinding involves the use of coarse ore particles as media. The predominant grinding mechanism is attrition (very little grinding is by impact).

Automation :
The process of controlling industrial production processes by computers or programmable logic-controllers (PLC) with a minimum of human involvement

Axial force:
A push (compression) or pull (tension) acting along the length of a member, expressed in kilonewtons (pounds).

Axial stress:
The axial force acting at a point along the length of a member divided by the cross-sectional area of a member, expressed in kilopascals (pounds per square inch).

Back connected:
A condition where pipe connections are on normally unexposed surfaces of hydraulic equipment.  (Gasket mounted units are back connected.)

Backfill:
A process whereby mine waste is used to fill a void created by mining out an orebody.

Back pressure:
A pressure in series.  Usually refers to pressure existing on the discharge side of a load.  It adds to the pressure required to move the load.

Bacterial leaching:
A bio hydrometallurgical process that uses bacteria (microorganisms) to extract metals from ore. The bacteria catalyse the oxidation of sulphite ore. Used in gold and copper mining.

Baghouse:
An air pollution control device that captures particulate in filter bags.

Ball mill:
Large rotating cylinder filled with metal balls that is used to break ore into smaller pieces.

Base metal:
Typically a non precious metal such as: Copper, Aluminum, Nickel, Tin, Zinc and Lead.

Basic rocks:
An igneous rock, relatively low in silica content and composed of mostly dark-colored minerals.

Battery:
An early method of crushing gold ore. Heavy iron pestles are continuously dropped into a trough containing water and the ore until it is fine enough to filter through screens.. Also called a stamp battery or stamp mill.

Bauxite:
A rock made up of hydrous aluminium oxides. The most common aluminum ore.

Beam:
Measurement of a boat at its widest point.

Bearings:
A part on which the arbor, pivot, pin, or the like, turns or revolves.

Bedrock:
Solid rock forming the Earth's crust, frequently covered by soil or water.

Belt conveyor:
A looped continuous belt on which material can be carried. Usually constructed of a rubber like substance riding over a pan or rollers shaped like a trough to hold the material in the center of the belt.

Benches:
Steps cut into the walls of an open pit mine. They provide working areas and a safe pit wall angle to be achieved.

Beneficiation:
The treatment of mined material, making it more concentrated or richer.

Biological leaching:
A bio hydrometallurgical process that uses bacteria (microorganisms) to extract metals from ore. The bacteria catalyse the oxidation of sulphite ore. Used in gold and copper mining.

Bit:
The smallest unit of memory in a computer.  A bit is a single digit and can only have the values 0 or 1.  Bits are combined into words of memory.

Bit:
The smallest unit of memory in a computer.  A bit is a single digit and can only have the values 0 or 1.  Bits are combined into words of memory.

Black damp:
A mixture of unbreathable gases including nitrogen, argon, carbon dioxide and water vapour which displaces oxygen in the air to a level incapable of sustaining human or animal life. Also called stythe or choke damp.

Blast furnace:
A metallurgical furnace used for smelting ores. Iron ore is most commonly treated in this way, and so are some ores of copper, lead, etc.

Blasthole:
A hole drilled for the purpose of placing explosives and blasting.

Blasting:
Detonating explosives to loosen rock and ore for excavation.

Blasting agent:
A material that has a mixture of a fuel and oxidizer. Normally refers to a relatively insensitive mixture such as ANFO, watergel or emulsion explosive.

Blasting cap:
A detonator containing a charge of detonating compound, which is ignited by electric current or the spark of a fuse.

Bleed-off:
To divert a specific controllable portion of hydraulic pump delivery directly to reservoir.

Block caving:
A method of mining where large blocks of ore are undercut which cause it to break or cave in under its own weight. An inexpensive method used when mining ore bodies with a consistent grade.

Boiler:
Steam generation equipment.

Bond strength:
The unit load applied in tension, compression, flexure, cleavage, or shear, required to break an adhesive assembly, with failure occurring in or near the plane of the bond.

Borehole:
A small diameter hole created when recovering a core for geological information. Also a hole used to plant explosives.

Boring:
Drilling holes into hard rock or driving a tunnel with a tunnel boring machine.

Braze:
As in welding, a method of adhering or soldering carbide or other hard metal teeth inserts, or joining pieces of metal.

Breaker:
Slang term for a rock crusher.

Breather:
A device which permits air to move in and out of a container or component to maintain atmospheric pressure.

Bridge carrier:
A mobile conveyor mounted on rubber tires. Used as an intermediary between a mining machine and room/entry conveyor.

British thermal unit (Btu):
The quantity of heat required to raise the temperature of one pound of water by one degree Fahrenheit.

Broken reserves:
Ore that has been broken by blasting inside the mine, but has not yet been transported to the surface.

Bucket line dredge:
A dredge that uses a chain of buckets to remove and lift gravels for further processing.

Bulk mining:
Large scale, mechanized mining operation where thousands of tonnes of ore are brought to the surface on a daily basis.

Bulk sample:
A large sample of mineralized rock selected to provide information about the overall properties of an ore body. Often used to determine metallurgical characteristics.

Byproduct:
Product of considerably less value than the major product. For example, the hide and offal are byproducts, while beef is the major product.

Cage:
Equipment used to transport men and equipment in a shaft.

Caisson:
Metal casing or cylinder used to sink shafts in wet or unstable ground.

Calcine:
Concentrate that is ready for smelting because the sulphur has been driven off by oxidation.

Calibration:
1.  Adjusting the control or recording equipment to reflect the actual control or recording
     temperatures.
2.  Procedures that involve scanning an object of known size.  Calibration is used to adjust
     scanner readings for greater accuracy.

Can velocity:
The velocity of the gas in the passages between the filter units in the filter house of a gas filter.

Capillarity:
Property of liquids allowing them to move through solids.

Capital cost:
The total investment needed to complete a project and bring it to a commercially operable status. The cost of construction of a new plant or the expenditures for the purchase/acquisition of existing facilities.

Car:
Railway wagon used to carry coal, ore and waste through underground tunnels.

Carat:
A unit of weight used for precious stones, equivalent to 200mg (3.08 grains).

Carbon adsorption:
A process where soluble complexes of gold and silver attach (without a chemical reaction) to the surfaces of activated carbon particles. Used to collect gold and silver from leach solution.

Car dump:
Mechanism used to unload a mining car or railway wagon.

Cartridge:
1.  The replaceable element of a fluid filter.
2.  The pumping unit from a vane pump, composed of the rotor, ring, vanes and one or both side
     plates.

Cast blasting:
A blasting method which uses the surplus explosive energy to move overburden/waste material across the pit and reduce the cost of handling it with mine equipment. Method frequently used in coal mining.

Cathode:
A rectangular plate of pure refined metal, produced in the electrolytic process of mineral refining. This plate is later melted into commercial shapes for final usage.

Cellulose:
One of the major structural materials in the plant cell walls that can be utilized by microorganisms in the rumen.

Celsius (C):
The international temperature scale in which water freezes at 0 and boils at 100 under normal atmospheric conditions.   °C = (°F - 32) ÷ 1.8.

Cement copper:
A copper product obtained from copper solution by precipitation (cementation) onto iron.

Centimetre (cm):
A metric unit of length equal to one hundredth of a metre.  2.54 cm is equal to one inch.

Centrifugal force:
The force which impels a thing, or parts of a thing, outward from a center of rotation.

Chain:
Survey measure equal to 66 feet (20.12 meters)

Chain conveyor:
Conveyor where material is moved along a trough by the scraping action of crossbars attached to a moving chain.

Chalcopyrite:
A sulphide mineral of copper and iron. A common ore mineral of copper.

Channel:
A fluid passage, the length of which is large with respect to its cross-sectional dimension.

Charge pressure:
The pressure at which replenishing fluid is forced into the hydraulic system (above atmospheric pressure).

Charge (supercharge):
1.  To replenish a hydraulic system above atmospheric pressure.
2.  To fill an accumulator with fluid under pressure. (See Precharge pressure)

Check valve:
A valve which permits flow of fluid in one direction only.

Choke point:
Area of the crushing chamber have the smallest cross section.

Chromite:
The chief ore mineral of chromium.

Cinnabar:
A vermilion-colored mercury sulfide mineral. It is the principal ore mineral for mercury.

Circuit:
An arrangement of components interconnected to perform a specific function within a system.

Circulating load:
Over sized pieces of ore returned to the head of a closed crushing/grinding circuit to be further reduced in size. After they reach the desired size they are moved on to the next processing step.

Clarification:
A filtering process to remove suspended material from water.

Classifier:
Mineral processing machine which separates minerals according to size and density.

Closed center valve:
One in which all ports are blocked in the center or neutral position.

Closed circuit:
A loop in the milling process where a selected portion of the product of a machine is returned to the head of the machine for finishing to required specification.

Coal:
A solid, brittle, more or less distinctly stratified combustible carbonaceous rock, formed by partial to complete decomposition of vegetation.

Column:
A free standing axially loaded compression member, usually vertical.

Column flotation:
A tall cylindrical column used to separate valuable or unwanted minerals from the gangue.

Command signal (or input signal):
An external signal to which the servo must respond.

Comminution:
The particle size reduction of materials. Breaking, crushing or grinding of coal, ore or rock.

Compensator control:
A displacement control for variable pumps and motors which alters displacement in response to pressure changes in the system as related to its adjusted pressure setting.

Complex ore:
An ore which contains a number of different minerals of value. Often means that it will be difficult to extract and separate the valuable minerals.

Composites:
Built-up, bonded products consisting wholly of natural wood, or in combination with metals, plastics, etc.

Compressibility:
The change in volume of a unit volume of a fluid when it is subjected to a unit change in pressure.

Compression:
In crushing/grinding terms the method of material reduction by applying a compression force between two surfaces.

Computer simulations:
Computer software that models actions or occurrences in the real world.

Concentrate:
Powdery product of high grade ore which has the majority of the waste (gangue) removed.

Concentrator:
The step(s) in a mineral processing mill which produces a concentrate of ore.

Cone crusher:
Machine that has a gyrating cone/crushing head to reduce the size of ore. Usually used as a secondary crusher.

Continuous miner:
A machine that constantly extracts coal while it loads it (with no stoppages).

Control:
A device used to regulate the function of a unit (See Hydraulic control, Manual control, Mechanical control, and Compensator control).

Control console:
Fabricated metal cabinet housing buttons and switches for the control of a machine center.

Controlled blasting:
Blasting patterns and sequences designed to achieve a particular objective. Examples include cast blasting and deck blasting.

Control valve:
A device that controls the flow of liquids or gases.

Conveyor:
Equipment which moves material from one point to another continuously by means of an endless (looped) procession of hooks, buckets, wide rubber belt, etc.

Core (Core sample):
A long cylinder of rock made during exploration work. Used for analysing the geologic and chemical properties of the ore body.

Counterbalance valve:
A pressure control valve which maintains back pressure to prevent a load from falling.

Cover:
The overburden or waste rock above an orebody.

Cracking pressure:
The pressure at which a pressure actuated valve begins to pass fluid.

Crib:
Roof support of prop timbers or ties. Arranged in alternating cross layer pattern.

Crusher / Crushing:
Machines which reduce the size of the ore to a specified size for further grinding in ball/rod mills. Types include jaw, gyratory, vertical/horizontal impactor, hydraulic hammer and cone.

Cushion:
A device sometimes built into the ends of a hydraulic or pneumatic cylinder which restricts the flow of fluid at the outlet port, thereby arresting the motion of the piston rod.

Cyanidation:
A method of extracting gold/silver from ore by dissolving it in a weak solution of sodium, calcium or potassium cyanide. Used as the primary method for gold/silver extraction, especially for low grade producers.

Cyanide:
A very toxic chemical used to dissolve gold and silver from the ore.

Cylinder:
A device which converts fluid power or air into linear mechanical force and motion.  It usually consists of a movable element such as a piston and piston rod, plunger rod, plunger or ram, operating within a cylindrical bore.

Damp:
Gases (other than air) in mines, usually in dangerous concentrations. Prefixes are attached to indicate various gases and situations (Black damp, white damp, fire damp, after damp, stink damp)

Deadband:
The region or band of no response where an error signal will not cause a corresponding actuation of the controlled variable.

Decompression:
The slow release of confined fluid to gradually reduce pressure on the fluid.

Delta:
The amount of change in a number, size or position.

Deposit:
Natural mineralization under the ground in sufficient quantities to warrant further exploration.

De-superheater:
A device for removing the excess heat in steam as its pressure is reduced.

Detectors:
Chemical or electronic instruments used to detect dangerous concentrations of mine gases.

Detonator:
Device containing a small charge used to detonate an explosive. Types include: blasting caps, delay electric blasting caps, exploders, electric detonators, etc.

Development drilling:
Drilling for the purpose of accurately estimating mineral reserves.

De-vent:
To close the vent connection of a pressure control valve permitting the valve to function at its adjusted pressure setting.

Diamond:
Hardest known mineral, composed of pure carbon.

Differential current:
The algebraic summation of the current in the torque motor; measured in MA (milliamperes).

Differential cylinder:
Any cylinder in which the two opposed piston areas are not equal.

Diffusion:
Movement of moisture from areas of high to low concentration or temperature.

Dilution:
Waste rock that is unavoidably removed and mixed in with the ore. This lowers the grade of the ore.

Directional valve:
A valve which selectively directs or prevents fluid flow to desired channels.

Disseminated ore:
Ore spread more or less uniformly through the waste rock (gangue). Opposite of Massive ore.

Dither:
A low amplitude, relatively high frequency periodic electrical signal, sometimes superimposed on the servo valve input to improve system resolution.  Dither is expressed by the dither frequency (Hz) and the peak-to-peak dither current amplitude (ma).

Dore:
Unrefined gold or silver bullion bars which still need further processing to become pure metal.

Dragline:
Large surface mining equipment used to remove overburden above a deposit. Has a long boom and large bucket which is thrown outwards, then dragged back towards the machine.

Drain:
A passage in, or a line from, a hydraulic component which returns leakage fluid independently to reservoir or to a vented manifold.

Dredging:
Process of using a machine to dig up and sift through placer deposits in a watercourse.

Dressing:
Treatment of ores to concentrate their minerals into concentrates and to collect waste to be discarded as tailings.

Drill:
Machine using rotation, percussion (hammering) or a combination of both to make holes.

Drill hole:
A small diameter hole created when recovering a core for geological information. Also a hole used to plant explosives.

Dump:
Waste material extracted during mining and placed on the surface in a large pile. Also known as a waste dump, pile, heap, tip, spoil, pike, etc. Also the actual act of unloading or the mechanism for unloading a load.

Dump truck:
A large earth moving vehicle whose carrying box can be tilted to discharge its load.

Efficiency:
The ratio of output to input.  Volumetric efficiency of a pump is the actual output in gpm divided by the theoretical or design output.  The overall efficiency of a hydraulic system is the output power divided by the input power.  Efficiency is usually expressed as a percent.

Electro-hydraulic servo valve:
A directional type valve which receives a variable or controlled electrical signal and which controls or meters hydraulic flow.

Electrolysis:
Process where an electric current is passed through a solution containing dissolved metals, causing the metals to be deposited on to a cathode.

Electrostatic separator:
Machine using static electrical charges to separate mineral concentrates.

Element:
Substance composed of atoms that can't be broken down further by ordinary means.

EM survey:
A geophysical method of surveying where the electromagnetic properties of rocks are measured.

Encoder:
Device attached to a moving chain that produces an electrical signal each time the chain moves a fixed distance.  The encoder is attached to the chain and used to track the movement of the pieces through a scanner.

Energy:
The ability or capacity to do work.  Measured in units of work.

Environment:

The aggregate of physical, chemical and biological factors that act upon an organism or an ecological community and ultimately determine its form and survival.


Environmental study:
Study done to determine how a proposed mining operation would impact the natural surrounding and wildlife.

Error (signal):
The signal which is the albraic summation of an input signal and a feedback signal.

Evaluation:
The calculated cost of mine construction in comparison to the value of the deposit.

Evaporate:
Changing water from a liquid to a vapor form.

Excess air:
Refers to the quantity of air supplied that exceeds the minimum necessary to support the combustion chemistry.

Exploration:
The search for new mineral/ore deposits. Includes prospecting, sampling, mapping, drilling, etc.

Explosive:
Rapidly combustive or expanding substance whose energy released can be used to break rock.

Extraction:
The mining and removal of ore from a mine.

Fahrenheit (F):
The temperature scale in which water freezes at 32 degrees F and boils at 212 degrees F under normal atmospheric conditions.  F = (C x 1.8) + 32.

Fan pitch:
The angle of the fan blades measured one-third of the fan radius in from the tip.

Fans, variable-speed:
Fans whose motors turn at infinitely variable speeds by varying the line frequency of the power source.

Feasibility study:
The financial or economic evaluation of the entire costs of building, putting a mine into production and whether the mine can make a profit at current/future mineral prices.

Feldspar:
A crystalline mineral consisting of aluminum silicates and other elements that is an essential ingredient for the ceramics industry, and also is used in the glass and paint industries.

Ferrous:
Adjective used to indicate the presence of iron.

Fill:
Material put back in place of extracted ore to provide ground support.

Filter:
A device whose primary function is the retention by a porous media of insoluble contaminants from a fluid.

Fineness:
Content of gold expressed in parts per thousand.

Fire damp:
Flammable gas found in mines created by decomposition of coal or other carbonaceous matter. Often refers to methane gas which is explosive at concentrations between 5% and 15%.

Fissile:
Ability to split or remove in sheets. Slate and mica are examples.

Fixed assets:
Buildings, machinery and land which are unlikely to be converted to cash during the normal business cycle.

Flight:
Metal crossbar attached to the chain of a drag chain or flight conveyor.

Flotation:
Milling process that uses bubbles to capture valuable minerals particles that float to the surface, thereby separating them from waste which sinks to the bottom.

Flow control valve:
A valve which controls the rate of oil flow.

Flow rate:
The volume, mass, or weight of a fluid passing through any conductor per unit of time.

Fluid:
1.  A liquid or gas.
2.  A liquid that is specially compounded for use as a power-transmitting medium in a hydraulic
     system.

Flume:
A trough used to convey water.

Follow valve:
A control valve which ports oil to an actuator so the resulting output motion is proportional to the input motion to the valve.

Foot (ft):
A linear unit of length equal to 12 inches or a third of a yard (0.3048 m).

FOPS:
Falling object protective structure.

Force:
Any push or pull measured in units of weight.  In hydraulics, total force is expressed by the product P (force per unit area) and the area of the surface on which the pressure acts.  F = P x A.

Four-way valve:
A directional valve having four flow paths.

FPM:
Feet per minute.

Free gold:
Small particles (gold dust) or even nuggets, which are usually found on riverbeds or close to the surface when erosion or weathering has exposed deposits.

Free milling:
Used to describe recovery of gold or silver from ore using only concentrating methods (crushing, gravity separation or amalgamation).

Frequency:
1.  The number of cycles per second of alternating current (example: 60 cycles per second or 60
     hertz per second).
2.  The number of times an action occurs in a unit of time.  Frequency is the basis of all sound. 
     A pump or motor's basic frequency is equal to its speed in revolutions per second multiplied
     by the number of pumping chambers.

Friable:
Easy to break or crumbling naturally.

Front connected:
A condition wherein piping connections are on normally exposed surfaces of hydraulic components.

Full flow:
In a filter, the condition where all the fluid must pass through the filter element or medium.

Furnace:
An enclosed chamber or container used to burn biomass in a controlled manner to produce heat for space or process heating.

Fuse:
Cord shaped substance that is entrained with black powder that when lit, burns along the cord at a set rate. Used in the ignition of explosives.

Gallon (gal):
A unit of volume.  A US gallon is equal to 4 quarts or 231 cubic inches (approximately 3.79 liters).  A British imperial gallon is equal to four quarts or 4.55 liters.

Gangue:
Waste rock contained within or surrounding an ore. This waste must be separated for the extraction of the mineral.

Gauge pressure:
A pressure scale which ignores atmospheric pressure.  Its zero point is 14.7 psi absolute.

Geiger counter:
An instrument used to measure radioactivity by means of a Geiger-Mueller tube. Certain minerals emanate radioactivity.

Geology:
Science and study of the earth's rocks and its composition.

Geophysical survey:
A scientific method of prospecting that measures the physical properties of rock formations. Common properties investigated include magnetism, specific gravity, electrical conductivity and radioactivity.

Geophysics:
The study of the physical properties of rocks and minerals.

Glue:
Originally, a hard gelatin obtained from hides, tendons, cartilage, bones, etc., of animals.  Also, an adhesive prepared from this substance by heating with water.  Through general use the term is now synonymous with the term "Adhesive".

Gold:
A heavy, soft, yellow, ductile, malleable, metallic element. The unique properties of this precious metal make it an essential component in a diverse number of products.

Grade:
Concentration of metal or minerals in a body of rock. Expressed as a percentage or grams per tonne.

Gram (g):
A metric unit of weight equal to one thousandth of a kilogram; one ounce is approximately 28 grams.

Granite:
An coarse-grained (intrusive) igneous rock consisting of quartz, feldspar and mica.

Gravity meter (gravimeter):
An instrument for measuring the local acceleration due to the Earth's gravity. Gravity varies with the density of the rocks in the vicinity.

Gravity separation:
The separtion of gold from waste. Due to gold being denser than the waste, it sinks to the bottom when shaken in a pan with water.

Greenhouse gases:
Gases that provide an insulating effect in the earth's atmosphere, potentially leading to global climate change. These gases include carbon dioxide, methane, nitrous oxide, ozone, and water vapour.

Grinders:
Equipment to reduce the size of the ore to a powder. Types include ball mills, rod mills, autogenous(AG) mills, semiautogenous (SAG) mills, pebble mills, grinding rolls, etc.

Grinding:
The final stage in reducing the size of the ore to a powder (below 5-20 mm). A powdering or pulverising process achieved by tumbling, stirring or vibration.

Grizzly:
Course screening or scalping device that prevents oversized bulk material form entering a material transfer system.  Constructed of rails, bars, beams, etc.

Gyratory crusher:
A machine that crushes ore between an eccentrically mounted crushing cone and a fixed crushing throat.

Hammermill:
Equipment used to reduce particle size. Achieved by impact with swinging hammers.

Hammermill rods:
Rods inside the hammermill, which the hammers attach to.

Hammermill screens:
Perforated screens inside a hammermill used to separate particle sizes. Particles successfully reduced by the hammer mill pass through the screen and leave the hammer mill with the aid of a pneumatic system.

Haulage:
The horizontal transport of ore, coal, supplies and waste.

Head:
The height of a column or body of fluid above a given point expressed in linear units.  Head is often used to indicate gage pressure.  Pressure  is equal to the height times the density of the fluid.

Headframe:
Structure supporting the shaft and hoist (hoisting) pulley. Often refers to the hoist itself.

Head section:
The area of a conveyor used for discharging material. Most often this is the location of the conveyor drive (motor/gearbox).

Heat:
The form of energy that has the capacity to create warmth or to increase the temperature of a substance. Any energy that is wasted or used to overcome friction is converted to heat.  Heat is measured in calories or British thermal units (Btu's).  One Btu is the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit.

Heat exchanger:
A device which transfers heat through a conducting wall from one fluid to another.

Hectare (ha):
A metric unit of area, 100 metres by 100 metres (10,000 square metres); equivalent to 2.471 acres.

Helical:
Spiral-shaped: in the shape of a helix or spiral.

Hertz (Hz):
Unit of frequency; equal to one cycle per second (cps).

Hoist:
A drum on which hoisting rope is wound.

Hoisting:
The vertical transport of ore, coal, supplies and waste.

Horsepower (hp):
The power required to lift 550 pounds one foot in one second or 33,000 pounds one foot in one minute.  A horsepower is equal to 746 watts or to 42.2 British thermal units per minute.

Host rock:
A layer of rock which holds or surrounds the mineral bearing rock.

Hydraulic:
To move or convey by fluid.

Hydraulic balance:
A condition of equal opposed hydraulic forces acting on a part in a hydraulic component.

Hydraulic control:
A control which is actuated by hydraulically induced forces.

Hydraulics:
Engineering science pertaining to liquid pressure and flow.

Hydrodynamics:
Engineering science pertaining to the energy of liquid flow and pressure.

Hydrostatics:
Engineering science pertaining to the energy of liquids at rest.

Hygrometer:
An instrument for measuring the humidity of air.

Hygroscopic:
Changes its moisture content to be in equilibrium with the atmosphere.

Ilmenite:
An ore mineral of titanium, being an iron-titanium oxide.

Impact:
In crushing/grinding terms the instantaneous collision of one moving object against another. Both can be moving or one object can be motionless. Types of impact are gravity impact and dynamic impact.

Inch (in):
A unit of length equal to one-twelfth of a foot (2.54 cm).

Indicated resource:
Term to describe the size of a resource that has had exploration drill holes spaced closely enough together to reasonably indicate that it has a continuous size and depth.

Induced polarization:
Geophysical surveying technique using an electrical current to determine indications of mineralization.

Industrial minerals:
Non-metallic, non-fuel minerals used in their natural state in the chemical and manufacturing industries. They require some beneficiation. Examples: asbestos, gypsum, salt, graphite, mica, gravel, building stone and talc.

Inferred resource:
Term to describe a resource whose size and grade has been estimated on limited sampling data. Often used in the early stage of exploration.

Jackhammer:
Rock breaking pneumatic hammer or rock drill.

Jaw crusher:
A compression type crusher with consists of two metal plates that crush material as they close together. Typically used in primary crushing as a means of preparing rocks for subsequent crushing stages.

Joule (J):
1.  A unit of energy equal to the work done when a force of one newton acts through a distance
     of one metre.  One joule is equivalent to one watt second or 0.737 foot pounds.
2.  A unit of electrical energy equal to the work done when a current of one ampere is passed
     through a resistance of one ohm for one second.

Key:
A small, parallel-sided piece, flat or tapered on top, for securing pulleys and other parts to shafts.

Keyway:
A groove or channel for a key, as in a shaft or the hub of a pulley; a keyseat.

Kilogram (kg):
The basic unit of mass in the SI system, equal to 1,000 grams (approximately 2.2 lbs).

Kilometre (km):
A measure of length equal to 1,000 metres or 0.62 miles.

Kimberlite:
The most common host rock of diamonds.

Kinetic energy:
Energy that a substance or body has by virtue of its mass (weight) and velocity.

Koepe Hoist:
Friction hoisting system in which the winding drum is replaced by large wheels or sheaves over which an endless rope passes.

Laminar (flow):
A condition where the fluid particles move in continuous parallel paths.

Laminate:
A product made by bonding together two or more layers (laminations) of material or materials.

Lamp:
Electric powered cap lamp worn for visibility. Also a flame safety lamp used in coal mines to detect mine gases or lack of oxygen.

Launder:
Chute or trough for conveying pulp, water or powdered ore in a mill.

Layback:
Amount of waste rock to be mined in order to achieve a safe working angle of an open pit wall.

Leachable:
Extractable by chemical solvents.

Leaching:
Chemical process to dissolve and extract minerals from ore. Also a natural process by which ground waters dissolve minerals.

Leg wires:
Wires attached to a electric blasting cap. Used to initiate detonation.

Lens:
Body of ore that is thick in the middle and tapers near the ends.

Level:
Perfectly horizontal.

Leverage:
A gain in output force over input force by sacrificing the distance moved.  Mechanical advantage or force multiplication.

Lift:
The height a body or column of fluid is raised; for instance, from the reservoir to the pump inlet.  Lift is sometimes used to express a negative pressure or vacuum.  The opposite of head.

Limit switch:
Electrical device that transmits an electrical signal when in physical contact with an object.

Line:
A tube, pipe or hose which acts as a conductor of hydraulic fluid.

Linear actuator:
A device for converting hydraulic energy into linear motion - a cylinder or ram. 

Liter (l):
Basic unit of volume in the metric system equal to 1,000 cubic centimetres (1.056 US quarts).

Load:
To pack explosives in a drill hole or to place material into a haulage device.

Loader:
Any of a variety of machines, wheel or track mounted, designed primarily to lift and load a truck, train or other mode of transportation.

Loading pocket:
Transfer point where bulk material is loaded by bin, hopper and chute into a skip.

Longwall mining:
Coal mining method where narrow vertical slices are cut by mechanical means along long faces or walls.

Magazine:
A place where explosive materials are stored.

Magnetic gradient survey:
Geophysical survey using two magnetometers a fixed distance apart to measure the difference in magnetic field between them.

Magnetic separation:
Mineral processing technique where a magnetic mineral is separated from gangue minerals by applying a strong magnetic field. Common in the treatment of ores of iron.

Magnetic survey:
Geophysical survey that measures the intensity of the Earth's magnetic field.

Magnetic susceptibility:
A measure of the degree to which a rock is attracted to a magnet.

Magnetite:
Magnetic iron ore, being a black iron oxide containing 72.4% iron when pure.

Magnetometer:
An instrument used to measure the magnetic attraction of underlying rocks.

Manifold:
A fluid conductor which provides multiple connection ports.

Manual control:
A control actuated by the operator, regardless of the means of actuation.  Example: Lever or foot pedal control for directional valves.

Manual override:
A means of manually actuating an automatically-controlled device.

Marble:
A metamorphic rock derived from the re-crystallization of limestone by the application of heat and pressure.

Marginal deposit:
An orebody of minimal profitability.

Massive ore:
Ore consisting of minerals in almost solid form with very little waste rock (gangue).

Material balance:
A relationship, often portrayed in a diagram, that shows how all components of a raw material are allocated and used.

Matrix:
The rock or gangue material containing ore minerals.

Matte:
A product of a smelter, containing metal and some sulphur which must be refined further to obtain pure metal.

Mechanical control:
Any control actuated by linkages, gears, screws, cams or other mechanical elements.

Mercury:
A silvery metal that is a liquid at room temperature. The principal ore mineral of mercury cinnabar.

Mesh:
Openings in a sieve or screen.

Metallurgical coal:
Coal used to make steel.

Metallurgy:
The science of ore processing, metal extraction and metals.

Meter:
To regulate the amount or rate of fluid flow.

Meter-in:
To regulate the amount of fluid flow into an actuator or system.

Meter-out:
To regulate the flow of the discharge fluid from an actuator or system.

Methane:
A potentially explosive gas formed naturally from the decay of vegetative matter. Frequently encountered in underground coal mining operations.

Methane monitor:
An electronic instrument that detects and measures the methane content of mine air. Provides an early warning if dangerous concentrations are reached.

Metre (m):
The metric basic unit for linear measurement equal to 39.37 inches (1.094 yards).

Micron:
One-millionth of a metre or approximately .00004 inch.

Micron rating:
The size of the particles a filter will remove.

Mile (mi):
A unit of linear measurement on land, equivalent to 5,280 feet (1,760 yd) or 1.6 kilometres.

Mill:
To Mill, verb - grind ingredients to make Meal or noun - a synonym for Meal.

Milligrams in a Kilogram (mg/kg):
Units of concentration. This measure is the same as parts per million (ppm). 1 mg/kg = 1 ppm

Millimetre (mm):
A unit of length equal to one thousandth of a metre (0.0394 inches).

Milling ore:
Ore that contains enough valuable minerals to be treated

Miner:
Someone who extracts ore, coal, precious substances, or other natural materials from the earth's crust.

Mineral:
Naturally occurring homogeneous substance that has a definite uniform chemical composition and characteristic crystalline structure.

Misfire:
Complete or partial failure of a blasting cap or charge to explode as planned.

Modulate:
To control within an infinite range between 0 percent and 100 percent as opposed to on/off control.

Monitor:
Screen on which an electronics systems display information.

Mother lode:
Any major ore vein running through a region.

Motor:
A device which converts electricity or hydraulic fluid power into mechanical force and motion.  It usually provides rotary mechanical motion.

Muck:
Ore or rock that has been broken by blasting.

Nanotesla:
International SI unit for measuring magnetic flux density.

Native gold:
Gold in its free state. Also called placer gold or free gold.

Native metal:
A metal occurring in nature in pure form, uncombined with other elements.

Natural ventilation:
Mine ventilation without the aid of fans or furnaces.

Newton (N):
Unit of force equivalent to the force that produces an acceleration of one metre per second per second on a mass of one kilogram.

Nonel:
Hollow plastic tube coated with a reactive explosive compound used to trigger explosions. No electric current is used.

Non-metallic:
Containing little or no metal; industrial mineral.

Open center circuit:
One in which pump delivery flows freely through the system and back to the reservoir in neutral.

Open center valve:
One in which all ports are interconnected and open to each other in the center or neutral position.

Open pit:
A surface mine, open to daylight. Also referred to as open-cut or open-cast mine.

Ore:
A mixture of ore minerals and gangue from which at least one of the metals can be extracted at a profit.

Orebody:
A natural concentration of valuable material that can be extracted and sold at a profit.

Ore dressing:
Removal of waste and the preparation/concentration of ore.

Ore grade:
Amount of minerals contained in an ore. Expressed as a percentage or grams per tonne.

Oreshoot:
The portion, or length, of the vein, or other ore structure, that carries sufficient valuable mineral to be extracted profitably.

Orifice:
A restriction, the length of which is small in respect to its cross-sectional dimensions.

Overburden:
Waste rock or cover above an orebody.

Oxidation:
Chemical reaction caused by exposure to oxygen that results in a change in the chemical composition of a mineral.

Pad:
Impermeable foundation used as a base for ore during heap leaching.

Parts per million (ppm):
1 milligram per kilogram = 1ppm = 1 pound per million pounds.

Pascal (Pa):
A unit of pressure or stress equal to one newton per square metre.

Peat:
Partially decayed plant material found in swamps and bogs. One of the earliest stages of coal formation.

Percussion drill:
A drill that delivers its energy through a pounding or hammering action.

pH:
The degree of acidity or alkalinity of a solution.  pH levels below 7 are acidic and above 7 are alkaline.

Photocell:
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.

Pilot pressure:
Auxiliary pressure used to actuate or control hydraulic components.

Pilot valve:
An auxiliary valve used to control the operation of another valve.  The controlling stage of a 2-stage valve.

Piston:
A cylindrically shaped part which fits within a cylinder and transmits or receives motion by means of a connecting rod.

Pitch:
Theoretical distance a propeller would travel in one revolution. Also, the rise and fall of a boat's bow and stern.

Pitchblende:
An important uranium ore mineral, containing a high percentage of uranium oxide.

Placer:
Alluvial deposit of sand and gravel containing valuable metals such as gold.

PLC:
Programmable logic controllers.  Industrial computer with I/O capability, which programs in ladder-relay logic.

Plumb:
Straight up and down, perfectly vertical.

Plunger:
A cylindrically shaped part which has only one diameter and is used to transmit thrust.  A ram.

Polishing pond:
The last settling ponds through which mill effluent flows before being discharged into the natural environment.

Polymetallic:
Complex ores containing profitable amounts of more than one valuable mineral.

Poppet:
That part of certain valves which prevents flow when it closes against a seat.

Port:
An internal or external terminus of a passage in a component.

Positive displacement:
A characteristic of a pump or motor which has the inlet positively sealed from the outlet so that fluid cannot recirculate in the component.

Potentiometer:
A control element in the servo system which measures and controls electrical potential.

Pound (lb):
A unit of weight equal to 16 ounces (0.45 kilograms).

Power:
Work per unit of time.  Measured in horsepower (hp) or watts (W).

Power pack:
An integral power supply unit usually containing a pump, reservoir, relief valve and directional control.

Precharge pressure:
The pressure of compressed gas in an accumulator prior to the admission of liquid.

Precipitate:
Material that settles from a liquid solution when a particular substance is added to the solute.

Preparation plant:
A plant where coal is cleaned, sized, and prepared for market.

Pressure:
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).

Pressure burst:
A seismic event whereby there is a sudden release of energy in a mine, much like a mini-earthquake.

Pressure drop:
The difference in pressure between any two points of a system or a component.

Pressure line:
The line carrying the fluid from the pump outlet to the pressurized port of the actuator.

Pressure override:
The difference between the cracking pressure of a valve and the pressure reached when the valve is passing full flow.

Pressure plate:
A side plate in a vane pump or motor cartridge on the pressure port side.

Pressure reducing valve:
A valve which limits the maximum pressure at its outlet regardless of the inlet pressure.

Pressure switch:
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.

Pre-Stripping:
Removing the waste rock (overburden) to gain access to an ore body below.

Primary deposits:
Ore minerals deposited during the original period or periods of metallization as opposed to those deposited as a result of alteration or weathering.

Probable reserves:
Valuable mineralization that has been not sampled enough to accurately estimate the tonnage and grade.

Proportional flow:
In a filter, the condition where part of the flow passes through the filter element in proportion to pressure drop.

Prospecting:
The search for valuable mineral deposits.

Proven reserves:
Reserves that have been sampled extensively and in sufficient detail to render an accurate estimation of grade and tonnage.

Proximate analysis:
A physical test of the constitution of coal that is not precise, but very useful for determining the commercial value.

Proximity switch:
Photoelectric switches that are triggered as a piece passes near them.  Proximity switches are used to detect the presence or absence of material.

PSI:
Pounds per square inch.

Pulp:
Pulverized or ground ore in solution.

Pump:
A device which converts mechanical force and motion into hydraulic fluid power.

Qualitative analysis:
Process of determining which metals are present in a sample.

Quality control:
Any activity that helps to maximize the value of the raw material through all phases of the manufacturing process.

Quantitative analysis:
Process of determining how much of a metal is present in a sample.

Radon survey:
Geochemical survey technique which detects traces of radon gas, a product of radioactivity.

Ram:
A single-acting cylinder with a single diameter plunger rather than a piston and rod.  The plunger in a ram-type cylinder.

Rank:
The classification of coal by degree of hardness, moisture and heat content.

Rare earth elements:
Scarce minerals such as scandium and ytrium.

Receiver:
Head of a scanner that monitors the infrared signals transmitted by the transmitter head.

Reciprocation:
Back-and-forth straight line motion or oscillation.

Reclamation:
The process of returning the land to another productive use or restoring the land to its approximate original appearance after mining has been completed.

Recovery:
1.  Product recovery: An expression of the amount of product (nominal or actual) that can be
     manufactured from a given input of raw material.
2.  Logging recovery: The volume or weight of logs that can be harvested from a given volume of
     standing timber.

Recovery (product):
An expression of the amount of product (nominal or actual) that can be manufactured from a given input of raw material.

Refining:
Extracting and purifying metals and minerals.

Refractory ore:
Ore that resists the action of chemical reagents in the normal treatment processes.

Regenerative circuit:
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.

Relief valve:
A pressure operated valve which by-passes pump delivery to the reservoir, limiting system pressure to a predetermined maximum value.

Replenish:
To add fluid to maintain a full hydraulic system.

Resistivity survey:
Geophysical survey technique used to measure the resistance of a rock formation to an electric current.

Resolution:
The smallest unit used for taking measurements from a scanner or the encoder.

Restriction:
A reduced cross-sectional area in a line or passage which produces a pressure drop.

Retort:
Used to separate or vaporize off mercury from gold.

Return line:
A line used to carry exhaust fluid from the actuator back to sump.

Reverberatory furnace:
A long, flat furnace used to slag gangue minerals and produce a matte.

Reversing valve:
A four-way directional valve used to reverse a double-acting cylinder or reversible motor.

Ripper:
Coal extraction machine that tears the coal from the face.

Roast:
Heating an ore to drive off volatile substances or oxidize the ore.

Rockburst:
A sudden failure of walls or pillars in a mine, caused by the weight or pressure of the surrounding rocks.

Rock mechanics:
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.

Rod mill:
Rotating steel cylinder that uses steel rods as a means of grinding ore.

Roller:
A cylindrical body movable about its longitudinal axis.

Room and pillar mining:
Underground coal mining method in which approximately half of the coal is left in place to support the roof of the active mining area

Rotary actuator:
A device for converting hydraulic energy into rotary motion - a hydraulic motor.

Rotary drill:
A machine that drills holes by rotating a rigid, tubular procession of drill rods to which is attached a bit.

Round:
Planned pattern of drill holes fired in sequence in tunneling, shaft sinking, or stopping.

RPM:
Revolutions per minute.

RTD:
A temperature measuring device that measures the change in electrical resistance to determine temperature (resistive thermal device).

Rung:
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.

Run of mine (ROM):
Material from a mine that has not been crushed or screened.

Run of quarry (ROQ):
Material from a quarry that has not been crushed or screened.

Salting:
The act of introducing metals or minerals into a deposit or samples, resulting in false assays. This can be done with the intent of defrauding the public or by accident.

Sample:
A small portion of rock or a mineral deposit, taken so that the metal content can be determined by assaying.

Scanner:
Generally an optical or laser/camera measuring device.  Scanners are composed of a transmitter head and a receiver head, which permit electronics system to obtain the shape and the dimensions an object.

Scintillation counter:
An instrument used to detect and measure radioactivity. More sensitive than a geiger counter. Certain minerals emanate radioactivity.

Screening equipment:
The sifter (also referred to as sieves, screens and screeners) is a separator, usually oscillating, with a number of screens. It is used to separate crumbles or granules by particle size depending on the size of hole used in the screens.

Secondary deposit:
Ore minerals deposited as a result of alteration or weathering of a primary deposit.

Sedimentary:
Formed by the deposition of eroded material and laid down by rivers and streams.

Seismic prospecting:
Geophysical method of prospecting using the known speed of reflected sound waves in rock.

Selective mining:
Mining with the goal to obtain a relatively high-grade mine product. Often results in higher exploration and development costs.

Semi-autogenous grinding:
Semi-autogenous grinding involves the use of coarse ore particles and an additional charge of steel balls as media. The predominant grinding mechanism is attrition and impact.

Sequence:
The order of a series of operations or movements.

Sequencing valve:
A pressure operated valve which, at its setting, diverts flow to a secondary line while holding a predetermined minimum pressure in the primary line.

Servo mechanism (servo):
A mechanism subjected to the action of a controlling device which will operate as if it were directly actuated by the controlling device, but capable of supplying power output many times that of the controlling device, this power being derived from an external and independent source.

Servo valve:
Electro-mechanical device used to control a setworks hydraulic cylinder.  An electrical signal is sent to the servo valve which opens, allowing hydraulic fluid to flow into the cylinder.  The voltage level and direction of the electrical signal determine the speed and direction of the setworks movement.

Set complete:
The actual position of a setworks is within a certain distance of the command position to which it was sent.

Set complete range:
The maximum distance allowed between the actual position of a setworks and the position to which the setworks was sent.  When the setworks position is in this range, the setworks is at set complete.

Shale:
Rock with a laminated structure formed from clay, mud, or silt. Composed of minerals essentially unaltered since deposition.

Shearer:
Equipment used in longwall mining. It uses a rotating action to "shear" the material from the face as it progresses.

Sheave wheel:
A large grooved wheel in the top of a headframe over which the hoisting rope passes.

Shieve:
Common term for a pulley.

Shim:
A thin piece or strip of metal used to fill in, as in leveling.

Short ton:
2,000 pounds or 0.9072 tonnes.

Shortwall mining:
Underground mining method where small areas are worked by a continuous miner.

Signal:
A control impulse from a control device or sensor.

Single jack:
A light hammer used for drilling holes by hand.

Sinter:
Fine particles of iron ore that have been treated by heat to produce blast furnace feed.

Slag:
The vitreous mass separated from the fused metals in the smelting process.

Smelter:
A facility where metal is separated by fusion (melting) from those impurities with which it may be chemically combined or physically mixed, such as in ore.

Solvent extraction-Electrowinning (SX-EW) :
A metallurgical technique, so far applied only to copper ores, in which metal is dissolved from the rock by organic solvents and recovered from solution by electrolysis.

Specimen:
A selected piece of rock or ore taken for examination or display.

Sphalerite:
Sulphide mineral of zinc. A common ore mineral of zinc.

Spiral concentrator:
Revolving drum or pan with an interior section made of spiral riffles. Used for gravity concentration of heavy minerals.

Spool:
A term loosely applied to almost any moving cylindrically shaped part of a hydraulic component which moves to direct flow through the component.

Stamp mill:
An early method of crushing gold ore. Heavy iron pestles are continuously dropped into a trough containing water and the ore until it is fine enough to filter through screens. Also called a stamp battery.

Stink damp:
A hydrogen sulphide gas that is very poisonous with a pungent smell of rotten eggs. Seldom found in dangerous quantities.

Stockpile:
Mined ore kept aside prior to processing which could be used as a strategic above-ground ore reserve.

Strip:
To remove the overburden or waste rock overlying an orebody in preparation for mining by open pit methods.

Strip mine:
Open pit mine, mined by removing overburden and excavating the coal or ore.

Stripping Ratio:
Waste to ore ratio that needs to be removed from an open-pit mine.

Stroke:
1.  The length of travel of a piston or plunger.
2.  To change the displacement of a variable displacement pump or motor.

Sub-plate:
An auxiliary mounting for a hydraulic component providing a means of connecting piping to the component.

Suction line:
The hydraulic line connecting the pump inlet port to the reservoir or sump.

Sulphur dioxide:
Gas liberated during the smelting of most sulphide ores.

Supercharge:
1.  To replenish a hydraulic system above atmospheric pressure.
2.  To fill an accumulator with fluid under pressure (See Precharge pressure).

Surge:
A transient rise of pressure or flow.

Survey:
Exploration technique to locate the presence of a potential ore body. Geophysical, geochemical and airborne based methods are used.

Swash plate:
A stationary canted plate in an axial type piston pump which causes the pistons to reciprocate as the cylinder barrel rotates.

Sylvite:
The principal ore of potassium.

Synchro:
A rotary electromagnetic device generally used as an AC feedback signal generator which indicates position.  It can also be used as a reference signal generator.

Tachometer (AC) (DC):
A device which generates an AC or DC signal proportional to the speed at which it is rotated and the polarity of which is dependent on the direction of rotation of the rotor.

Taconite:
A highly abrasive iron ore.

Tailings:
Material rejected from a mill after most of the recoverable valuable minerals have been extracted. Normally consists of ground up rock in the sand to silt size range.

Tailings pond:
A pond to confine tailings. It allows enough time for heavy metals to settle out or for cyanide to be destroyed before water is discharged into the environment.

Tail section:
The area of a conveyor at the extreme opposite end from the discharge point. Most often this is the location of the take up device for adjusting belt or chain tension.

Tamping:
The act of packing a substance in behind an explosive to make it air tight and therefore work more efficiently.

Temposonics:
Linear displacement transducer.

Tenor:
The relative value or mineral content of an ore.

Thermocouple (TC):
A sensor that measures temperature based on the voltage difference between  two dissimilar metals.

Thermosetting glues and resins:
Glues and resins that are cured with heat but do not soften when subsequently subjected to high temperatures.

Thickener:
A large, round tank used to separate solids from liquids. Fluid overflows from the tank and rock particles sink to the bottom.

Tonne:
A unit of weight in the metric system equal to 1,000 kilograms or approximately 2,204 pounds.  Also called a Metric ton.

Tonnes-per-vertical-metre:
Common unit used to describe the amount of ore in a deposit.

Ton (T):
1. US unit of weight equal to 2,000 lb; also called a Short ton.
2. British unit of weight equal to 2,240 lb (1,016 kg); also called a Long ton.

Torque:
A rotary thrust.  The turning effort of a fluid motor usually expressed in inch pounds.

Torque converter:
A rotary fluid coupling that is capable of multiplying torque.

Torque motor:
A type of electromechanical transducer having rotary motion used in the input stages of servo valves.

Tramp:
Foreign uncrushable metal often found in rock crushing input.

Transducer (or feedback transducer):
An element which measures the results at the load and sends a signal back to the amplifier.

Transfer point:
Location in the materials handling system, either haulage or hoisting, where bulk material is transferred between conveyances.

Traps:
A device that separates condensate and air from the steam within the steam heating coils.

Traps, float and thermostatic:
Traps that discharge condensate at a rate dependent on the position of an internal float.  Air is removed through a thermostatic air vent.

Traps, inverted bucket:
Mechanical traps that operate on the difference in the density between steam and water.

Traps, thermostatic:
Traps that use an internal bellows, which expands when steam flows to the trap, closing the orifice.  As condensate accumulates the bellows contracts to release it.

Trommel:
A screen contained within a tumbling mill which acts like a sieve during ore processing.

Troy ounce:
Unit of weight measurement used for all precious metals.

Tube mill:
Large rotating cylinder filled with metal balls that is used to break ore into smaller pieces. Similar to a ball mill but has a longer length compared to its diameter.

Tunnel-boring-machine:
A machine used to excavate a tunnel through soil or rock by mechanical means as opposed to drilling and blasting.

Turbine:
A rotary device that is actuated by the impact of a moving fluid against blades or vanes.

Turbulent flow (turbulence):
A condition where the fluid particles move in random paths rather than in continuous parallel paths.

Two-way valve:
A directional control valve with two flow paths.

Ultimate analysis:
Determination, by chemical means, of the elements and compounds in coal.

Ultra basic:
Igneous rocks containing less than 35% silica.

Umpire sample (assay):
An assay made by a third party to provide a basis for settling disputes between buyers and sellers of ore.

Uninterruptible power supply (UPS):
Provides conditioned power and battery backup for computers in the case of a power failure or brownout.

Unload:
To release flow (usually directly to the reservoir), to prevent pressure being imposed on the system or portion of the system.

Unloading valve:
A valve which by-passes flow to tank when a set pressure is maintained on its pilot port.

Uraninite:
A uranium mineral with a high uranium oxide content.

Uranium:
A radioactive, silvery-white, metallic element.

Vacuum:
Pressure less than atmospheric pressure.  It is usually expresses in inches of mercury (in Hg) as referred to the existing atmospheric pressure.

Values:
The valuable minerals contained in a deposit, usually refers to the precious metal content.

Valve:
A device which controls fluid flow direction, pressure, or flow rate.

Vein:
A mineralized area having a more or less regular development in length, width and depth. It is clearly separated from neighboring rock.

Velocity:
The speed of flow through a hydraulic line.  Expressed in feet per second (fps) or inches per second (ips).

Vent:
To permit opening of a pressure control valve by opening its pilot port (vent connection) to atmospheric pressure.

Viscosity:
A measure of the internal friction or the resistance of a fluid to flow.

Viscosity index:
A measure of the viscosity-temperature characteristics of a fluid as referred to that of two arbitrary reference fluids.

Waste:
Rock or mineralized material that is too low in grade to be mined and milled at a profit.

White damp:
Carbon monoxide gas almost always found in the after damp following an explosion of coal dust or fire damp in a mine. Extremely poisonous, lighter than air, colorless, odorless and tasteless.

Wobble plate:
A rotating canted plate in an axial type piston pump which pushes the pistons into their bores as it "wobbles".

Work:
The application of  force over a definite distance.  Work (W) = Force (F) x distance (s). Expressed in joules, ergs, and foot-pounds. The joule is exactly the amount of work done in exerting the basic metric unit of force, 1 newton, over the basic metric unit of distance, 1 metre.

Yardage:
The number of cubic yards of gravel contained in a placer deposit. Also the number of cubic yards mined and processed per hour or per day.

Yard (yd):
Unit of length equal to 3 feet (91.5 centimetres).

Yield:
An expression of the amount of product (nominal or actual) that can be manufactured from a given input of raw material. Also referred to as product recovery.

Zone of oxidation:
The upper portion of an orebody that has been oxidized.