Comparing stope performance relative to the engineering design is of paramount importance for any mining operation. A database was created of 105 stopes mined between 170 m and 800 m below surface from July 2014 to November 2016 at the Goldcorp Eleonore mine. The database consists of more than 20 parameters defining spatial, mining, geometrical, geological, drill-and-blast, and temporal stope properties. Univariate and bivariate statistical analyses were conducted using the database to better understand the root causes of stope performance. The study has allowed parameters controlling stope performance to be identified. These are the spatial localization of the stope (mining horizon, mining lenses, and central location within the orebody), the mining method, and the orientation of the major structures relative to stope orientation, the global stope drilling pattern and the stand-up time.
Open stope mining is one of the most commonly used mining methods in Canada, allowing high levels of mechanization and thus increased productivity. Maximization of stope value is closely linked to achieving the planned or engineered stope shape. Stope performance is therefore computed by comparing the planned stope shape with the actual or mined shape. The latter is obtained using a cavity monitoring survey system (CMS) (Miller, Potvin, and Jacob, 1992).
Stope overbreak (OB) is defined as the volume of rock by which the actual stope shape exceeds the planned stope shape. Stope underbreak (UB) is the inverse. In narrow vein mining, stope performance is usually assessed by measuring the equivalent linear overbreak/slough (ELOS), as proposed by Clark (1998). This is calculated by measuring the ratio between OB volume and the area of a given stope surface: hangingwall, footwall, crown, or endwalls.
Although conceptually defined in 3D, the common computing methodology used in the mining industry to evaluate ELOS relies on 2D calculations on various sections or slices cut along the stope (Cepuritis and Villaescusa, 2006). In large bulk-mining operations, stope performance is generally calculated by dividing the total OB volume by the planned stope volume (Potvin et al., 2016; Suorineni, 2010). The latter measurement is generally expressed in percentages. This computation, although to a lesser extent, is also regularly computed in 2D along stope sections or slices.