Bitumen flotation

There are many other applications of zeta potential, some of which are discussed in later sections, including mineral flotation (Section 10.3.1), bitumen flotation (Section 11.3.2), paper-making (Section 12.2), and many others. 

The large Canadian oil-sands surface-mining and water-based flotation processing operations involve a number of kinds of emulsions and foams in a variety of process steps. Whereas mineral ore flotation relies on wettability alteration and bubble attachment, oil and bitumen flotation rely more on attachment and filming to create an oleic foam. 

A > 0, S > 0. Here the bitumen would attach and then spread over the gas bubble. Once the bitumen encapsulates a gas bubble only very high mechanical shear would cause it to be stripped away. This is the best configuration for bitumen flotation in a primary separation (flotation) vessel. 

Uses Emulsifier for bitumen flotation collector for feldspar, pyrochlor Genamin TAP 100 D [Clariant/Functional Chems.)... 

Flotation or froth flotation is a physicochemical property-based separation process. It is widely utilised in the area of mineral processing also known as ore dressing and mineral beneftciation for mineral concentration. In addition to the mining and metallurgical industries, flotation also finds appHcations in sewage treatment, water purification, bitumen recovery from tar sands, and coal desulfurization. Nearly one biUion tons of ore are treated by this process aimuaHy in the world. Phosphate rock, precious metals, lead, zinc, copper, molybdenum, and tin-containing ores as well as coal are treated routinely by this process some flotation plants treat 200,000 tons of ore per day (see Mineral recovery and processing). Various aspects of flotation theory and practice have been treated in books and reviews (1 9). 

An attempt has been made to develop the hot-water process for the Utah sands (Fig. 10) (20). With od-wet Utah sands, this process differs significantly from that used for the water-wet Canadian sands, necessitating disengagement by hot-water digestion in a high shear force field under appropriate conditions of pulp density and alkalinity. The dispersed bitumen droplets can also be recovered by aeration and froth flotation (21). 

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. 

Fifty years have elapsed since the first major surge occurred in the development of the Athabasca oil sands. The main effort has been devoted to the development of the hot water extraction process 13 significant projects utilizing this process are reviewed in this paper. However, many other techniques have also been extensively tested. These are classified into several basic concepts, and the mechanism underlying each is briefly described. A critical review of K. A. Claries theories concerning the flotation of bitumen is presented, and his theories are updated to accommodate the different mechanisms of the primary and secondary oil recovery processes. The relative merits of the mining and in situ approaches are discussed, and an estimate is made of the probable extent of the oil sand development toward the end of this century. 

The first three methods in Table I differ in the manner in which the oil phase is separated from the water. In the hot water process, the bitumen flecks are attached to air bubbles to effect flotation. 

Statements 2 to 5. These were modified appreciably in the 1949 revision. In the earlier version, Clark believed that the properties of the water phase were very important in oil—sand separation, and he emphasized the role of air in floating the bitumen particles. In the later version, both these variables were given less emphasis. The critical factor was believed to be the association of clay with oil to form the somewhat mysterious flecks, which formed froth by submission to conditions to bring the flecks in contact with the water-air interface. In the body of the 1949 paper Clark left no doubt that convection currents were the mechanism not flotation in the normal sense of air-oil attachment. Clark backed up his new theory with some very revealing tests on simple clay-oil dispersions. Before discussing the merits of the two sets of statements, it would be of value to examine new data not available to Clark at that time. 

Emulsions may contain not just oil, water, and emulsifier (usually a surfactant), but also solid particles, and even gas. Figure 1.3 shows a practical O/W emulsion that contains suspended particles in addition to the oil drops. In the large Canadian oil sands mining and processing operations bitumen is separated from the sand matrix, in large tumblers, as an emulsion of oil dispersed in water, and then further separated from the tumbler slurry by a flotation process. The product of the flotation... 

Example. In the primary flotation vessel of an oil sands processing plant, two different process conditions yield the following data for the flotation of bitumen mean bitumen droplet diameter, 0.26 mm, mean droplet density,... 

Example. Bitumen is recovered in the form of a froth when a separation-flotation process is applied to surface mined oil sand. Once de aerated, this bituminous froth is a W/O emulsion from which the water must be removed prior to upgrading and refining. At process temperature (80 °C) the emulsion viscosity is similar to that of the bitumen, but the density, due to entrained solids, is higher. Taking t) = 500 mPa-s and f> = 1.04 g/mL, the rate of creaming of 20 pm diameter water droplets under gravitational force will be very slow ... 

Table 6.3 Range of viscosities encountered in the flotation recovery of bitumen from ...

Foams and emulsions may also be encountered simultaneously [114]. Figure 1.5 shows an example of an aqueous foam with oil droplets residing in its Plateau borders (see Section 5.6.7). In addition to containing gas, an aqueous phase, and an oleic phase, foams can also contain dispersed solid particles. Oil-assisted flotation of mineral particles provides one example (Chapter 10). Oil-sand flotation of bitumen provides another (Chapter 11). In the case of oil-sands flotation, an emulsion of oil dispersed in water is created and then further separated by a flotation process, the products of which are bituminous froths that may be either air (and water) dispersed in oil (from primary flotation) or air (and oil) dispersed in water (from secondary flotation). In either case, the froths must be broken and de-aerated before the bitumen can be upgraded to synthetic crude oil. (See Section 11.3.2). 

The raw minerals mined from natural deposits comprise mixtures of different specific minerals. An early step in mineral processing is to use crushing and grinding to free these various minerals from each other. In addition, these same processes may be used to reduce the mineral particle sizes to make them suitable for a subsequent separation process. Non-ferrous metals such as copper, lead, zinc, nickel, cobalt, molybdenum, mercury, and antimony are typically produced from mineral ores containing these metals as sulfides (and sometimes as oxides, carbonates, or sulfates) [91,619,620], The respective metal sulfides are usually separated from the raw ores by flotation. Flotation processes are also used to concentrate non-metallic minerals used in other industries, such as calcium fluoride, barium sulfate, sodium and potassium chlorides, sulfur, coal, phosphates, alumina, silicates, and clays [91,619,621], Other examples are listed in Table 10.2, including the recovery of ink in paper recycling (which is discussed in Section 12.5.2), the recovery of bitumen from oil sands (which is discussed further in Section 11.3.2), and the removal of particulates and bacteria in water and wastewater treatment (which is discussed further in Section 9.4). 

A consequence of the application of flotation technology to oil sands bitumen production is the co-production of tailings suspensions, consisting of fine silica and clays plus some residual emulsified bitumen. This is discussed in somewhat more general terms in Section 10.4. See also Refs. [638,642]. 

Figure 11.9 I llustration of the connection between hot water flotation efficiency and measured chemical and physical properties, including bitumen zeta potential From Schramm and Smith [250]. Copyright 1987, Canadian Society for Chemical Engineering.

A flotation separation process, in which particles or droplets become attached to gas bubbles that are injected (sparged) into the flotation medium. Also termed induced gas flotation . Example the froth flotation of bitumen. See also Froth Flotation. 

Foamed emulsions are disperse systems with two disperse phases (gas and liquid) in the disperse medium (surfactant solution). Water foamed emulsions are formed when foams or aqueous surfactant solutions are used to clean up oil deteriorated surfaces, in the process of oil flotation of waste waters, in firefighting when the foam contacts various organic liquids and in the processes of chemical defoaming (foam destruction by antifoams). Individual foamed emulsions can have practical importance e.g. a foamed emulsion of bitumen is used in road coating foamed emulsions from liquid fuels are used as explosives. 

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.)...

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