Mineral emulsion flotation

Traditionally, monolayer and multilayer adsorption have been used in detergency, mineral processing, flotation, stability of food and pharmaceutical emulsions, and the like, and, as a consequence, the topics of this chapter have been a central part of colloid science. In recent years, however, research on monolayer and multilayer deposition has mushroomed rapidly because of significant new opportunities. 

Emulsion flotation is analogous to carrier flotation. Here, small-sized particles become attached to the surfaces of oil droplets (the carrier droplets). The carrier droplets attach to the air bubbles and the combined aggregates of small desired particles, carrier droplets, and air bubbles float to form the froth. An example is the emulsion flotation of submicrometre-sized diamond particles with isooctane. Emulsion flotation has also been applied to the flotation of minerals that are not readily wetted by water, such as graphite, sulfur, molybdenite, and coal [623]. Some oils used in emulsion flotation include mixed cresols (cresylic acid), pine oil, aliphatic alcohols, kerosene, fuel oil, and gas oil [623], A related use of a second, immiscible liquid to aid in particle separation is in agglomeration flocculation (see Section 5.6.4). 

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. 

In achieving solid-solid separation in mineral beneficiation, selective coatings of water insoluble or sparingly soluble reagents are required in electronic ore sorting, froth flotation, and emulsion flotation operations. 

Surfactant adsorption at solid surfaces is, in practice, exploited to facilitate detergency, control wetting and penetration of solutions, stabilize foams and emulsions, and collect minerals in flotation operations. From this list alone, it is clear that this field is of tremendous importance. Consequently, significant effort has been directed toward acquiring a better understanding of the adsorptive nature of different surfactant molecules at solid surfaces. ... 

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). 

Suspensions are created at an early stage of processes used to separate valuable minerals or oil by froth flotation (Chapter 10). Suspensions are also quite important and widespread in the petroleum industry (Chapter 11) and, like emulsions and foams, suspensions may be encountered throughout each of the stages of petroleum recovery and processing (in reservoirs, drilling fluids, production fluids, process-... 

Many of the applications of colloid and interface science to the mining and mineral processing industry can be found in the hydrotransport, flotation, and tailings processes. Although suspensions feature prominently in each of these, a range of emulsions, foams and suspensions can be found in this industry. Some examples are given in Table 10.1. 

Use Demulsifier used particularly in the recovery of tar from water-gas process emulsions. A powerful cationic wetting agent. Useful in flotation processes involving siliceous minerals and the formation of emulsions and dispersions under acidic conditions. 

The basic interfacial process in flotation is selective hydrophobization (or lepophiliza-tion) and hydrophilization of particulate matter. The role of the solution chemistry is very important in flotation as it is determined by the dissolution behavior of mineral particles in the aqueous solution (pulp) and subsequent dissociation, hydrolysis and precipitation of the soluble species the dissolution, association, dispersion and emulsion behavior of various flotation reagents in the pulp and interactions among reagents with both soluble and surface species of minerals. The efficiency of flotation and separation of mineral particles and consumption of reagents are thus controlled by the solution chemistry of the pulp. As other processes such as oil displacement are also governed by such interactions and in turn by the wettability of the solid surface, the study of solution chemistry of surfactant/mineral/additive systems become very important for the development of many technologies. 

Chem. Descrip. 1-Hydroxyethyl-2-tall oil imidazoline CAS 61791-39-7 EINECS/ELINCS 263-171-2 Uses Intermediate for quat. ammonium compds. strongly absorbed on textiles, paper and many metal surfs. for agric., asphalL cleaners, corrosion inhibitors, demulsifiers, flotation, metalworking, paints, pigment grinding, inks, textiles, wax emulsions Properties Amber liq. sol. in mineral/vegetable oils, dilute sol ns. of mineral acids, orq. soivs., si. sol. in water m.w. 350 sp.qr. 0.945 pH 10-11 (2%sol n.)... 

Uses Binder, emulsion stabilizer, vise, control agent, emulsifier, film-former, protective colloid, stabilizer, suspending agent, thickener in foods, cosmetics, pharmaceuticals thickener, protective colloid in emulsion paints, adhesives binder in ceramics suspending agent in PVC polymerization protective colloid in suspension polymerization mineral flotation depressant hair preps. in blow-molded bottles tablet coating aid in... 

Diethylamlne is a water-white liquid with an ammoniacal odor. It is soluble In water, ethyl alcohol, paraffin hydrocarbons, aromatic and aliphatic hydrocarbons, ethyl ether, ethyl acetate, acetone, fixed oils, mineral oil, oleic and stearic acids. It dissolves hot poraffin ond carnauba waxes, which solidify when cooled. It Is used as a selective sal-vent for the removal of impurities from oils, fats, ond waxes where Its property of hydrating in aqueous solution is utilized olso used In the manufocture of rubber chemicals, textile emulsions, dyes, flotation agents, resins, polymerlzotlon Inhibitors, gum inhibitors, drugs, and Insecticides. 

Uses Antistat, binder, emulsion stabilizer, film-former, vise, control agent, thickener, suspending agent, stabilizer, slip agent, flocculant in cosmetics mineral flotation depressant textile auxiliaries vise, builder for oil-well workover/completion fluids binder, surfactant, lubricant, plasticizer in ceramics dry str. and formation aid in mfg. of paper/paperboard in contact with aq.ffatty foods... 

Chronologically there were almost no reports on this topic prior to the early 1980s, and the first of these concerned studies on xanthate electrooxidation to assist froth flotation in mineral-ore recovery. The mechanisms of flotation are not completely imderstood, and for xanthates the involvement of dixanthogen and other species has been proposed. In an early paper, combined use of ultrasound and electrooxidation was found to increase the amount of dixanthogen and give a uniform emulsion with 80% of droplets below 5 pm diameter, improving the recoveries of galena, sphalerite, and chalcopyrite. ... 

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