The influence of natural surfactants on interfacial charges in the hot-water process for recovering bitumen from the athabasca oil sands

doi:10.1016/0166-6622(85)80042-1

Colloids and Surfaces

Volume 14, Issue 1, 1985, Pages 67-85

https://doi.org/10.1016/0166-6622(85)80042-1 Get rights and content

Abstract

Studies of the processibility of a variety of types of Athabasca oil sands have been carried out to discover the physical action of the natural surfactants in the hot-water flotation process. In particular, the electrophoretic mobilities of the dispersed oil and fine mineral phases were measured.

Natural surfactants, produced in the process, appear to act to increase the (negative) charges at the oil/solution and solid/solution interfaces. In the case of the oil/solution interface, the electrophoretic mobility passes through a maximum as a function of solution surfactant concentration. The condition under which this maximum is achieved is associated with maximum efficiency of the hot-water flotation process.

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A middlings stream drawn from the central part of the PSC, and tailings drawn from near the bottom of the PSC are sent to conventional mechanical flotation cells to recover the remaining bitumen. The process has been shown to produce high recoveries for bitumen-rich estuarine ores, although poorer performance on leaner marine ores (Schramm and Smith, 1985a). A key characteristic of the Canadian oil sands is the thin water film surrounding the sand grains, which renders them easy to release from the bitumen using water-based methods such as the Clark hot-water process.
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Schramm and Smith (1985) explained that at high pH the concentration of surfactants in solution increases. These surfactants adsorb at the air–water and bitumen–water interfaces and lower the corresponding interfacial tensions thus facilitating the formation of an air-in-bitumen dispersion of rather low density (Schramm and Smith, 1985). It appears that such a mechanism, essentially equivalent to engulfment of air bubbles by bitumen, contributes to the high level of bitumen flotation from ore 2 at high pH.
The processability of four oil sand ores was evaluated through batch flotation experiments under different conditions of pH and temperature. The data of bitumen recovery were accurately modeled using a first-order kinetic equation assuming that the total amount of bitumen in the system consisted of two bitumen components, i.e., a fully-liberated bitumen fraction, f, characterized by a high flotation rate constant (k_f), and poorly-liberated bitumen fraction, s, of a low flotation rate constant (k_s) so that f + s = 1. The role of humic acids naturally present in the ores was basically that of a depressant of bitumen since poor ores contained the highest proportion of humic acids per gram of bitumen. The recovery of bitumen from oil sand ores correlated very well with the absorbance at 520 nm of the alkali extracts produced from the ores. High bitumen recovery was achieved for ores characterized by a low absorbance value of the extract, while low bitumen recoveries were obtained for ores producing a high absorbance value in the alkali extraction test.
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The influence of natural surfactants on interfacial charges in the hot-water process for recovering bitumen from the athabasca oil sands

Abstract

Int. J. Miner. Process.

Colloids Surfaces

J. Colloid Interface Sci.

Colloids Surfaces

J. Colloid Interface Sci.

Fuel Process. Technol.

Proc. 7th World Petrol. Congr.

Can. J. Chem. Eng.

AOSTRA J. Research

AOSTRA J. Research

Can. J. Chem. Eng.

Can. J. Chem. Eng.

J. Can. Petrol. Technol.