Hot-water flotation process

Ali, L. H. Surface-Active Agents in the Aqueous Phase of the Hot-Water Flotation Process for Oil Sands, Fuel, 1978, 57, 357. 

Bitumen is recovered using a caustic assisted hot water flotation process and diluted with naphtha to facilitate the removal of residual solids and water. Diluent naphtha is removed by distillation prior to feeding bitumen to the Upgrading facilities. 

Example. Consider the observed properties of bituminous froth produced in the oil sands hot water flotation process. When fresh, the froth is very viscous when stagnant (hard to pump) but becomes less viscous (twice as easy to pump) when it is flowing. As it is handled, or stored, the entrained air is released and it becomes less viscous (eventually six times as easy to pump). 

Example. A tailings stream from the hot-water flotation process (oil sands) contains 27 % (mass) solids. Estimate the suspension viscosity. Light-scattering analysis indicates that the particles are finely divided and anisotropic with a 10 Tm major dimension and a 0.5 pm minor dimension. Using Eq. 

Shaw, R.C. Czarnecki, J. Schramm, L.L. Axelson, D. Bituminous Froths in the Hot-Water Flotation Process in Foams Fundamentals and Applications in the Petroleum Industry, Schramm, L.L., Ed., American Chemical Society Washington, 1994 pp. 423-459. 

Figure 15. Plot of oil recoveries versus process aid addition level from the hot water flotation processing of an oil sand in a continuous pilot plant. Also shown is the correspondence with the zeta potentials, measured on-line, of emulsified bitumen droplets in the extraction solution. (Plotted from data in reference 50.)...

A special kind of nonaqueous foam known as bituminous froth is produced during the application of the hot-water flotation process to Athabasca oil sands, a large-scale commercial application of mined oil sands technology. These froths are multiphase, composed of oil, water gas, and solids, and form an interesting kind of petroleum industry foam. This chapter presents a review of the occurrence, nature, properties, and treatment of bituminous froths. 

Of the Canadian deposits, the largest, Athabasca, is at least 4 times the size of the largest conventional oil field, Ghawar, in Saudi Arabia (5). Of the Athabasca s estimated 600 billion barrels of bitumen, about 60 billion barrels could be recovered by surface mining of the oil sand followed by beneficiation to separate the oil. Currently two commercial plants are producing synthetic crude oil from the Athabasca deposit. In these operations, the oil sands are first mined, and the bitumen is extracted by a hot-water flotation process, which produces a bituminous froth. After breaking the froth, the separated bitumen is subsequently upgraded by refineiy-type processes to produce synthetic crude oil. In order to understand the nature of the froths produced, the nature of oil-sand structure will be reviewed first, and then the flotation process from which froths are produced will be examined. 

Figure 3. Diagram of a commercial oil-sands mining and hot-water flotation process. (Reproduced from refer- so...

Figure 4. Illustration of two of the steps in the hot-water flotation process a, the separation of bitumen from solids showing the adsorption of naturally produced surfactants and bf the attachment and filming of bitumen around gas bubbles.

As an illustration, consider the problem of removing solids and water droplets from deaerated bituminous froth produced from the oil sands hot water flotation process (see Chapter 13 and reference 35). This is a nonaqueous suspension from which the particles and water droplets must be removed before upgrading and refining. At process temperature (80 °C) the suspension viscosity is similar to that of bitumen alone, but the density, because of the dispersed solids, is higher. Taking rj = 500 mPa s (35), px = 1.04 g/mL and p2 = 2.50 g/mL, the rate of settling of 10 pm diameter solid particles under gravitational force will be very slow ... 

Suspensions in the Hot Water Flotation Process for Canadian Oil Sands... 

Figure 10. Relationship between the <44 pm particle size fraction in Athabasca oil sands and the amount of NaOH addition required to optimize the hot water flotation process, as determined by Sanford. (Reproduced with permission from reference 60. Copyright 1983 Canadian Society for Chemical Engineering.)...

Figure 12. Simplified block diagram of elementary process steps in the hot water flotation process for Athabasca oil sands.

Figure 14. Illustration of the steps involved in conducting a batch hot water flotation process test, after Schramm and Smith. (Reproduced with permission from reference 82. Copyright 1989 Alberta Oil Sands Technology and Research Authority.)...

We have shown that to apply the hot water flotation process to Athabasca oil sands, one must deal with suspensions of various kinds. The initial... 

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