: A number of potash mines around the world experience brine inflow occurrences and various associated structural and stability problems, as brine tends to dissolve the potash and salt strata. A novel study
has been carried out to simulate the effect of brine on the performance of mine pillar support. The testing program consisted of loading potash specimens in a creep frame to reproduce pillar loading, and then simulating the presence of brine using three different brine inflow scenarios. Brine temperature ranged between 20 °C and 60 °C, and pillar load conditions varied from unloaded to 50% of the unconfined compressive strength of the rock. Potash specimens were fitted with acoustic emission transducers to monitor energy emission and brine sampling was used to assess dissolution reactions. Tests results indicated that dissolution rates are highly dependent on the brine inflow pattern, brine temperature and load conditions. Loads approaching 50% UCS tend to generate very high rates of energy emission, often leading to the failure of the simulated pillars. The study demonstrated that acoustic emission could be effectively used for predicting the strength behavior and failure progression of pillars when exposed to inflow brine.
The first venture to mine potash ore in Canada, failed in 1951 due to flooding. Prugger and Prugger (1991) report that five of the seventeen potash shafts started in Saskatchewan experienced major water inflows or were completely flooded during shaft sinking. Potash mining carries a distinctive risk because potash rock is highly soluble in water. Brine inflow, sometimes at the rate of thousands of liters per minute, causes rapid erosion of the rock, weakening of mine structures and possible failure of mine excavations.