Studies of the infiltration and migration of brine in potash tailings

Abstract

A series of infiltration tests were conducted on the potash tailings pile at the Lanigan Division Potash Mine in Saskatchewan. These tests included single ring infiltrometer, shallow pit, open caisson and trench type infiltration tests. The fluid retention curves for the tailings were established in the field using tensiometers and neutron probes to monitor in situ negative fluid pressures and fluid contents respectively. These field-measured curves were then compared with the laboratory-evaluated fluid retention curves.The responses of the field instrumentation during the trench infiltration test were also compared with the results of a computer simulation of infiltration, which utilized the laboratory-evaluated fluid retention curve and the calculated permeability-suction curve as input data. The good agreement obtained between the measured and simulated field responses validates the application of saturated–unsaturated flow theory to the analysis of the flow of brine within the unsaturated tailings. It also verifies the accuracy of the fluid retention curve determined in the laboratory as well as the calculated permeability-suction curve. Key words: potash tailings, infiltration testing, single ring infiltrometer, tensiometer, neutron probe, saturated–unsaturated flow, fluid retention curve, permeability-suction curve, finite-element flow model.