stope

A stope is a working excavation in an underground mine where ore is extracted from a vein or lode. The term describes both the space itself and the action of creating it. Unlike simple shaft sinking or level driving, stoping means removing ore in a series of steps or benches, typically working upward from a lower access level toward the surface or a higher drive. The waste left behind after ore extraction, called stope fill or backfill, supports the walls and stabilizes the underground structure.

Stoping geometry varies with ore body shape and mining method. In a shrinkage stope, blasted ore is left partially in place to support the walls while additional material is extracted above it, then drawn down as mining proceeds higher. In a cut-and-fill stope, each blast is followed by filling the void with waste rock or tailings before the next level is mined. A sublevel stope divides the ore body vertically into sections, each worked from its own access point. Square-set stoping, used in narrow, unstable veins, employs timber frames or steel sets to brace the excavation as it grows.

Hazards and limitations

Stope stability depends on pillar strength, fill quality, and ore body dip angle. Steep-dipping veins (60 degrees or more) stope more reliably than shallow dips, where horizontal stress becomes critical. Failure modes include pillar collapse, hang-ups (ore bridging over an opening and refusing to drop), and dilution, where waste rock mixes with ore as boundary walls fail. Modern stopes in competent rock are mined with greater heights and wider spans than historical workings, but ground support requirements increase proportionally.

The word itself comes from Germanic mining tradition, though its exact origin is debated. Stoping appears in English mining texts from the 16th century and became standard terminology across hardrock mining. Continental miners used similar terms: in German, Stoß means a mining section or panel. The process is central to underground hardrock mining of gold, copper, nickel, and base metals, where grade and depth make surface extraction uneconomical.

Stoping efficiency depends on ore recovery, ground support cost, and fill placement rate. Modern operations use mechanized loaders, bolting systems, and paste fill (tailings mixed with cement) to improve safety and recovery. The choice between stoping methods shapes mine life, capital expenditure, and ore recovery rate, making stope design a core element of feasibility studies and mine planning.