Freeze-thaw dewatering of oil sands fine tails

Abstract

Laboratory and field experiments demonstrate that substantial dewatering occurs when the waste clay from oil sands operations is subjected to one cycle of freeze-thaw. The enhanced permeability resulting from the freezing process causes further dewatering and accompanying strength increases during post-thaw consolidation. The findings presented here were guided by a number of different materials handling scenarios which take advantage of the freeze-thaw process and are driven by the appropriate geotechnical, geochemical, and geothermal input parameters. Different conceptual design scenarios are examined to demonstrate how this process might be feasibly implemented at the commercial scale. Emphasis is placed on the large-scale requirements, sensitivity to input parameters, and the coupling of the continuing applied research with the conceptual materials handling models. The latter point is of generic interest to those involved in mine waste management.Key words: mine wastes, freeze-thaw, volume reduction, disposal, large strain consolidation.

Heave, settlement and fracture of chalk during physical modelling experiments with temperature cycling above and below 0°C

“…Thomachot and Matsuoka, 2007). Such consolation can result from freeze-thaw cycling of saturated fine-grained soils (Chamberlain and Gow, 1979) and mine tailings (Dawson et al, 1999), where it causes a net decrease in the void ratio and an increase in permeability. The freeze-thaw behaviour of the chalk was qualitatively similar to that of frostsusceptible soil because not only did ice segregation occur (Section 4.3.)…”

Experimental Verification of Morphological Instability in Freezing Aqueous Colloidal Suspensions

“…Besides presenting new challenges to our understanding of colloidal physics, the self-organization of freezing colloids plays an important role in many natural and technological processes. The phenomenon underlies frost heave and patterned ground [7,8], influences the success of cryopreservation [9], and provides a mechanism for the remediation of contaminated clay [10,11]. At low initial particle concentrations it is possible to remove the segregated ice by freeze drying to yield microaligned porous materials with uses in bioengineering and microfluidics [4,12].…”

Trickle-freeze separation of contaminants from saline waste water

“…The depth of ice that can be melted in a given year (based on works by Martel (1989) and Dawson et al (1999)) needs to be confirmed in the field, on site. The melting depth will determine the size of the freezing area required.…”

“…The size of the retaining structure was based on an annual treatment of 20 million m 3 /year of typical oil sands process water (half of the freshwater intake volume) and the thickness of ice that can be frozen or thawed annually. Based on previous freeze -thaw research on oil sands fine tails, the maximum thickness of ice produced each year in the Fort McMurray region is governed by the thawing season (Martel 1989, Dawson et al 1999. The estimated thickness of ice that can be melted in one year is 4.5 m. The current design utilized 16 individual containment (freezing) cells, each 545 m6545 m in plan, capable of storing ice 4.5 m thick (figure 3).…”