Adit: a mining passageway driven horizontally into a mountainside for the purpose of providing access to a mineral deposit.
Autoclave system: an oxidation treatment in which high temperatures and pressures are applied to convert refractory gold-bearing sulfide materials into amenable oxide ore.
Backfilling: the process whereby waste material is used to fill the void created by mining an orebody.
Ball mill: a steel cylinder loaded with steel balls into which crushed ore is fed. The ball mill is rotated, causing the balls to cascade and grind the ore.
By-product: a secondary metal or mineral product recovered in the milling process.
Carbon-in-leach: a recovery process in which a slurry of gold ore, carbon granules and cyanide are mixed together. The cyanide dissolves the gold content and the gold is adsorbed on the carbon. The carbon is subsequently separated from the slurry for further gold removal.
Carbon-in-pulp: similar to carbon-in-leach process, but initially the slurry is subjected to cyanide leaching in separate tanks followed by carbon-in-pulp. Carbon-in-pulp is a sequential process whereas carbon-in-leach is a simultaneous process.
Collar: the term applied to the timbering or concrete around the mouth of a shaft and the start of a drill hole.
Contained ounces: represents ounces (generally referring to gold) in the ground without the reduction of ounces not recovered by the applicable metallurgical process.
Concentrate: a powdery product containing the valuable ore mineral from which most of the waste material has been eliminated.
Cut-and-fill: a method of underground mining in which ore is removed in slices or lifts, and then the excavation is filled with rock or other waste material (backfill) before the subsequent slice is mined.
Cyanidation: a method of extracting gold or silver by dissolving it in a weak solution of sodium cyanide.
Development: underground work carried out for the purpose of opening up a mineral deposit. Includes shaft sinking, crosscutting, drifting and raising.
Doré: unrefined gold and silver bullion bars usually consisting of approximately 90 percent precious metals which will be further refined to almost pure metal.
Drift: a horizontal tunnel driven alongside an orebody, from either an adit or shaft, to gain access to the ore.
Diamond: drilling with a hollow bit with a diamond cutting rim to produce a cylindrical core that is used for geological study and assays. Used in minerals exploration.
Infill: diamond drilling at shorter intervals between existing holes, used to provide greater geological detail and to help establish reserve estimates.
Reverse circulation: drilling that produces rock chips rather than core; the chips are forced by air to the surface and are collected for examination and analysis. Faster and cheaper than diamond drilling.
Exploration: prospecting, sampling, mapping, diamond drilling and other work involved in searching for ore.
Flotation: a process by which some mineral particles are induced to become attached to bubbles and float, and other particles to sink, so that the valuable minerals are concentrated and separated from the worthless gangue or waste.
Gangue: Non-valuable materials associated with the ore minerals.
Grade: the amount of valuable mineral in each ton of ore, expressed as troy ounces per ton or grams per tonne for precious metals and as a percentage for other metals.
Cut-off grade: the minimum metal grade at which an ore body can be economically mined.
Millhead grade: metal content of mined ore going into a mill for processing. Usually lower than reserve grade because of dilution by non-ore grade materials.
Recovered grade: actual metal content of ore determined after processing.
Reserve grade: estimated metal content of an ore body, based on reserve calculations.
Heap leaching: a process whereby certain metals are extracted by "heaping" broken ore on sloping impermeable pads and repeatedly spraying the heaps with a solution that dissolves the valuable metal(s). The metal-laden solution is then collected for metal recovery.
Industrial minerals: a group of minerals that are important sources of raw materials for the chemical, metallurgical, construction, agricultural, and related industries.
Long-hole open stope: a method of mining involving the drilling of holes up to 90 feet long into an orebody and then blasting a slice of rock that falls into an open space. The broken rock is extracted and the resulting open chamber is not filled with supporting material.
Metric Ton: one million grams. A grade of 1 g/T = 1 ppm
Mill: a plant where ore is ground fine and the valuable minerals are recovered by physical and chemical processes.
Mineral deposit: any unusual mineral concentration, regardless of whether the valuable components can be extracted at a profit (see
and Ore body). Ore
Open pit: a mine that is entirely on the surface.
: rock from which one or more valuable metallic or non-metallic minerals can be mined and processed at a profit. Ore
body: a sufficiently large amount of ore that can be mined economically. Ore
Oxide ore: mineralized rock in which some of the original minerals have been oxidized. Oxidation tends to make the ore more porous which facilitates flow of solutions into the rock. This effect is particularly important for oxidized gold ore as it permits more complete permeation of cyanide solutions so that minute particles of gold in the interior of the mineral grains can be readily dissolved.
Ramp: an inclined underground tunnel that provides access for exploration or a connection between mining levels.
Reclamation: the process by which lands disturbed as a result of mining activity are reclaimed back to a beneficial land use. Reclamation activity includes the removal of buildings, equipment, machinery and other physical remnants of mining, closure of tailings impoundments, leach pads and other mine features, and contouring, covering and revegetation of waste rock piles and other disturbed areas.
Recovery rate: a term used in process metallurgy to indicate the proportion of valuable material obtained in the processing of an ore. It is generally stated as a percentage of the material recovered compared to the total material present.
Refractory material: gold-bearing rock in which the gold is not amenable to recovery by conventional cyanide methods without pre-treatment. The refractory nature can be either silica or sulfide encapsulation of the gold or the presence of naturally occurring carbons that reduce gold recovery.
Reserves: that part of a mineral deposit which could be economically and legally extracted or produced at the time of the reserve determination. Reserves are customarily stated in terms of ore when dealing with metallic minerals. There are two categories of reserves:
Proven ore: material for which tonnage and grade are computed from dimensions revealed in outcrops, trenches, underground workings or drill holes; grade is computed from the results of adequate sampling; and the sites for inspection, sampling and measurement are so spaced and the geological character so well-defined that size, shape and mineral content are established.
Probable ore: material for which tonnage and grade are computed partly from specific measurements, samples or production data and partly from projection for a reasonable distance based on geological evidence; and for which the sites available for inspection, measurement and sampling are too widely or otherwise inappropriately spaced to outline the material completely or to establish its grade throughout.
Roasting: the treatment of ore by heat and air, or oxygen-enriched air, in order to remove sulfur, carbon, antimony and arsenic.
Semi-autogenous grinding (SAG): a method of grinding rock into fine powder in which the grinding media consist of larger chunks of rock and steel balls.
Shaft: a vertical passageway to an underground mine for moving personnel, equipment, supplies and material including ore and waste rock.
Smelting: a metallurgical process in which metal is separated from impurities by a process that includes fusion.
Solvent extraction (SXEW): a type of heap leaching and subsequent processing used for secondary copper ores whereby the oxidized copper minerals are taken into solution. The copper-bearing solution is processed to recover metallic copper from the solution electrolytically.
Stope: an area in an underground mine where ore is mined.
Stripping ratio: the ratio of the number of tons of waste material removed to the number of tons of ore removed, used in connection with open pit mining.
Sulfide ore: refers to any type of ore in which the ore minerals are in the form of metallic sulfides. Commonly used for a sub-group of refractory gold ore mineralized rock in which much of the gold is encapsulated in sulfides and is not readily amenable to dissolution by cyanide solutions associated with sulfide minerals (primarily pyrite) that have not been oxidized. Some sulfide ore may require autoclaving or roasting prior to milling.
Tailings: the material that remains after all valuable minerals have been removed from the ore during milling.
Tonne: see Metric Ton
Troy ounce: the common measure of the precious metals. A troy ounce of a fineness of 999.9 parts per 1,000 parts, equal to 31.1034 grams.
Water management: process whereby the groundwater table in the mining area is lowered by pumping water from wells, and the water is conveyed and used or recharged to the groundwater system through infiltration, reinjection or irrigation return.
Modified from Barrick Gold Corporation.