Geotechnical behavior of uranium mill tailings from Saskatchewan, Canada

This paper investigates the geotechnical behavior of uranium mill tailings from Saskatchewan, Canada. The 4% tailings were well-graded with 29% fines whereas the 5% and 6% tailings were gap-graded with 49% fines. All samples exhibited a negligible strength (0.4 kPa) up to 60% solids, followed by a rapid increase. The 4% tailings exhibited a lower rate and amount of settlement than 5% and 6% tailings. The ki decreased from 10−2 to 10−4 m/s with a decrease in ei from 16 to 4 and a decrease in ef from 8 to 4 such that 4% tailings showed one order of magnitude lower values than the 5% and 6% tailings. The settling potential decreased ten times (50%–5%) for 4% tailings and four times (60%–15%) for 5% and 6% tailings. The effective stress increased from 80 to 260 Pa in the settling tests. The 4% tailings were less prone to segregation when compared with 5% and 6% tailings. The average solids content after settling was 35% for 4% tailings, 40% for 5% tailings and 39% for 6% tailings with a solids content deviation of ±3%, ±8%, ±6%, respectively. All materials were essentially non-segregating at 40% initial solids.