Strengthening of solidified dilute tailings slurry

Tailings produced during mineral processing contain up to 75% or more water and are pumped into settling ponds for disposal. They often become a pollu tion source due to acid generation. While tailings have been used in underg round backfill, the use is very limited at present. This paper presents res earch results on direct solidification and strengthening of the dilute tail ings slurry without dewatering. Two types of tailings were tested at water/ binder ratios of up to 4.5 using a special high-water binder. Adequate stre ngth was achieved by solidifying the tailings as is. To further improve the strength, sands and Ay ash were used as reinforcement materials or partial replacement of the binder. For oil sands tailings, the 3-day strength was increased by up to 114% with 10-15% additives. For hard rock tailings, up t o 30% strength gain was achieved with 15% fly ash addition, and the strengt h was increased by up to 36% at 10% binder replacement and no strength redu ction was observed at 20-25% replacement. These results indicate that highe r strength can be achieved with the proper amount of additives and that the backfill process can be simplified and the operation cost reduced.