Oil sands tailing pond

MacKinnon, M., Boerger, H. 1986. Description of two treatment methods for detoxifying oil sands tailings pond water. Water Pollution Research Journal of Canada., Vol. 21, pp. 496-512. 

An FTIR method has also been developed for the determination of the naphthenic acids in oil sand process tailings [97]. In this method, a tailings sample is clarified by filtration (0.45 pm nominal pore size) then by ultrafiltration. Acidification to pH 2.5 with sulfuric acid ensures the acid form of all carboxylate functionalities and thus complete dissolution. The sample is then extracted with methylene chloride and evaporated to dryness. The naphthenic acid residue is dissolved in methylene chloride, the carbonyl stretching frequencies at 1708 and 1748 cm are observed and the corresponding absorbance values determined by FTIR. The method determines total organic carboxylates and therefore is sensitive to a broader range of structures than the carboxylate surfactants alone, but is sometimes used as an indicator of relative carboxylate surfactant concentrations, especially in studies of oil sand tailings pond samples. 

The dispersive nature of the oil sands extraction process does not affect the settling properties of the coarse solids. These solids segregate from the fines and are used for building the dikes that surround the settling ponds that contain the process recycle water. The fines that are not retained with the beach solids run off into the tailings pond as a thin slurry and consolidate very slowly full consolidation of untreated tailings is estimated to take thousands of years. Large quantities of this suspension... 

A breakdown of the mineral compositions of a typical oil sand, overburden clay layers in the McMurray Formation, and the MFT are given in Figure 10. The figure shows that kaolinite and illite dominate the clay fraction in all of these materials, with smectites generally found only in the overburden and in intercalated clay lenses in the oil sands. The amounts and types of clay minerals found in tailings ponds vary considerably, but assays of tailings pond MFT show mostly kaolinite and illite (30-32). Montmorillonite has been reported in the Suncor MFT... 

The main sources of inorganic ions found in tailings water are (1) oil sand connate water (water in the spaces between the sand grains), (2) makeup water taken from the Athabasca River for use in plant processes, and (3) chemicals added during hot water extraction and other processes. These sources contribute ions that accumulate in the pond water that is recycled to oil sands processing. 

Bicarbonate (HC03 ) concentration increases in the tailings pond water because of its presence in the oil sands feed as well as from the adsorption of C02 during aeration in the conditioning stage in the extraction plant and, to a lesser extent, from absorption into the relatively high pH tailings pond water (30). 

Figure 14. Temperature profile of the Syncrude and Suncor tailings pond as a function of depth (Reproduced with permission from reference 3. Copyright 1989 Alberta Oil Sands Technology and Research Authority.)...

MacKinnon, M. D. Retallack, J. T. Preliminary Characterization and Detoxification of Tailings Pond Water at the Syncrude Canada Ltd. Oil Sands Plant, in Land and Water Issues Related to Energy Development, 4th Conference Rand, P. J., Ed. Ann Arbor Science Ann Arbor, MI, 1982 p 185. 

Industrial processing may lead to emulsions being discharged into tailings ponds, such as in the tailings ponds created by surface processing of mined oil sands [64,125]. 

Oil Spills and Tailings. Emulsions may be discharged to or created in tailings ponds, such as in the tailings ponds created by surface processing of mined oil sands (see Chapter 10 of this book). Oil is produced at off-shore drill sites in the form of oil-in-water emulsions (containing reservoir water) which may have to be transported to an onshore processing centre, at which the primary emulsion is separated into its components and the oil is often re-emulsified (fresh water) for other applications. 

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