Acid plant — A facility that recovers sulfur dioxide from discharged gases and manufactures sulfuric acid from it.

Block-caving — A process whereby large blocks of ore are undercut and allowed to fall and fracture into smaller pieces that can be loaded through chutes into mine cars and taken to the surface. It is the lowest-cost underground mining method.

Flotation — A method of combining finely ground ore with water and chemical reagents to create a frothy mixture that separates metallic particles from other minerals; the metallic particles are then collected and dried and the resulting concentrate is sent to the smelter for fire-refining.

Hydrometallurgy — The treatment of ores, concentrates and other metal-bearing materials by a wet process, such as SX/EW. This process is distinct from the pyro-metallurgy of a smelter.

In-pit crusher — Machines used to crush ore in an open-pit mine preparatory to sending it to a concentrator for further treatment.

Leaching — A process used to remove soluble minerals by percolating solutions through low-grade oxide and sulfide ores.

Mill — A building in which ore is crushed and ground to extricate valuable minerals.

Mining district — An area of land described for legal purposes and containing valuable minerals in payable amounts.

Open-pit mining — Surface mining method in which overlaying rock, or overburden, is removed to expose the ore body, which is then drilled, blasted, and loaded into trucks, or (formerly) railroad cars, for haulage from the pit.

Ore — Rock containing minerals in sufficient concentration, quantity, and value to be mined at a profit. The definition changes as technology improves, today’s ore being yesterday’s valueless pile of rock.

Overburden — Rock material of little or no value that overlies an ore deposit and must be removed before ore mining can begin.

Prospect — Mineral workings of unproved value.

Raise — A mine shaft driven from below upward.

Shaft — A vertical or nearly vertical opening into the earth for mining.

Skip — A container used to lift ore through a shaft and to the surface above a mine.

Slag — The waste product of a smelter.

Smelter — A metallurgical complex in which material is melted in order to separate impurities from pure metal.

Stope — Underground opening from which ore is extracted.

SX/EW — Abbreviation for the hydrometallurgical process known as solution-extraction – electrowinning that produces cathodes of 99.9 percent pure copper.

Tailings — Finely ground rock materials left after milling is complete; distinct from the old waste dumps, today’s low-grade ore stockpiles that contain rock not currently of sufficient value to warrant mining.