Fine tailings reclamation

Figure 10.10 Components of fine tailings reclamation. From Schramm et at. [642] Copyright 2000, Cambridge University Press.

Gulley, J. MacKinnon, M. Fine Tails Reclamation Utilizing a Wet Landscape Approach in Proc. Fine Tailings Symposium in Oil Sands Our Petroleum Future Conference Liu, J.K. (Ed.), Alberta Oil Sands Technology and Research Authority Edmonton, AB, 1993, Paper F23, 24 pp. 

Boerger, H. MacKinnon, M. Van Meer, T. Verbeek, A. Wet Landscape Option for Reclamation of Oil Sands Fine Tails in Proc. of the 2nd International Conference on Environmental Issues and Management of Waste in Energy and Mineral Production Singhal, R.K. Mehrotra, A.K. Fytas, K. Collins, J. (Eds.), Balkema Rotterdam, 1992, pp. 1248-1261. 

The chemical and physical properties of clay suspensions produced during oil production from oil sands are described. With a composition of approximately 70 wt% water (with some unrecovered bitumen) and 30 wt%solids (>90% less than 44 gm in size)9 these clay suspensions consolidate very slowly. Clay aggregate or floe morphology has been shown to be a function of the water chemistry and can be manipulated to produce a tailings suspension that is easier to consolidate and dewater. Commercial oil sands processing has been going on in northeastern Alberta since 1967, and in that time approximately 250 million m3 of this difficult to dewater clay suspension has been produced. The reclamation options for this material (mature fine tailings) on a commercial scale are also outlined. 

However, with ageing, the toxic response per unit of naphthenic acid decreases. From Fignre 38, the reduction in naphthenic acid content and of acnte toxicity with time for tailings waters, stored under aerobic conditions, is evident for an array of biota. Natural bioremediation processes are proceeding in the oil sands extraction waters, once they are removed from fresh input of process waters and maintained under aerobic conditions. This biodegradation process is the basis on which the both the wet and dry landscape reclamation options operate. With time, waters will be slowly released from the varions sinks (sand deposits, fine tails) in the end-lease landscape. If the rate of their release is less than the rate of the bioremediation processes, then the resulting waters should have the toxic components of the naphthenic acid group reduced to levels that will ensure the waters are neither acutely nor chronically toxic [136,142],... 

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