This paper discusses the use of a finite element program to calibrate a computer mine model with more than seven years field data, which were collected from a test site at the Rocanville potash mine in south-east Saskatchewan, Canada. This calibrated model was then used to predict behavior in another, largerscale test site of same room width, but in a different region of the mine and with slightly smaller rib pillar size between the rooms. Several hypothetical case studies were also conducted.
PotashCorp operates five underground potash mines in Saskatchewan and one in New Brunswick. At PCS Potash Rocanville Division (Fig. 1), potash is mined at approximately 3,150’ (960 m) below the surface. The mine is employs the long room and pillar mining method. The production panels are approximately 6000’ (1830 m) x 6000’ (1830 m). The 65’ (19.8m) wide rooms are mined in 3 passes, by using the four-rotor Eimco Marietta 780-AW4 Boring machine. Cutting height is 8’ (2.44 m). The rooms are separated by a 90’ (27.44 m) wide rib pillar that supports the overburden. The nominal extraction ratio is 41.9% within a production panel. The openings of large rooms are facilitated by a relatively thick salt cover of 80¡¯ (24.4 m). Actual mining and rock mechanics data collection over the last 35 years has established the stability of this 65¡¯ wide room and has encouraged experimentation with even wider room, namely 85'' (25.9 m). The wider room has the advantage of better productivity (four passes of the mining machine in one production room instead of three) allowing 25% more production utilizing the same extensible conveyor structure set-up.