Flotation materials

For reasons of corrosion in the vapor spaces and for ease of construction and cost, some floating cover designs have used nonferrous metals, primarily aluminum. Some designs have used encapsulated plastic flotation materials. These designs are generally considered more vulnerable to damage in a fire than those fabricated of metal components. API 650 and NFPA 30 classify these different designs as ... 

Topper Industries of Vancouver, Washington, has patented the concept of a material-filled floating tire. The concept employs scrap tires as a durable container for holding the flotation material together (13). Topper Industries is the only known producer of scrap tire flotation devices and that company estimates that they... 

The most important polyether polyols from this first group of low melting point starters are sorbitol-based polyether polyols, which are considered to be the universal polyols for rigid PU foams. They can be used in all applications of rigid polyurethane foams, such as thermoinsulation, wood imitations, packaging, flotation materials and so on. 

Collectors are surfactants that typically chemisorb at the surface of the flotated materials and make the latter hydrophobic. A clear chemical specificity of chemisorption allows one to carry out selective flotation, which is especially effective in stage separation of multicomponent minerals and... 

Table 6-19. Syntactic Plastic Foams as are Used in Deepwater Flotation Materials...

Positive displacement slurry pumps are used in a number of industries (Table 9-1). Solid piston pumps are reserved for the pumping of slurries of a low to medium abrasiveness (Miller Number <50) such as chalk slurry, fine coal, flotation material, and driUlng mud sludge. 

The applications of adsorption are widespread among the many Adds of practical importance based on this process, one can mention heterogeneous catalysis, flotation, material science, microelectronics, ecology, separation of mixtures, puriflcation of air and water, electrochemistry, chromatography, and so forth. 

When used to separate solid-solid mixtures, the material is ground to a particle size small enough to liberate particles of the chemical species to be recovered. The mixture of solid particles is then dispersed in the flotation medium, which is usually water. Gas bubbles become attached to the solid particles, thereby allowing them to float to the surface of the liquid. The solid partices are collected from the surface by an overflow weir or mechanical scraper. The separation of the solid particles depends on the different species having different surface properties such that one species is preferentially attached to the bubbles. A number of chemicals are added to the flotation medium to meet the various requirements of the flotation process ... 

A very important but rather complex application of surface chemistry is to the separation of various types of solid particles from each other by what is known as flotation. The general method is of enormous importance to the mining industry it permits large-scale and economic processing of crushed ores whereby the desired mineral is separated from the gangue or non-mineral-containing material. Originally applied only to certain sulfide and oxide ores. 

Prior to about 1920, flotation procedures were rather crude and rested primarily on the observation that copper and lead-zinc ore pulps (crushed ore mixed with water) could be benefacted (improved in mineral content) by treatment with large amounts of fatty and oily materials. The mineral particles collected in the oily layer and thus could be separated from the gangue and the water. Since then, oil flotation has been largely replaced by froth or foam flotation. Here, only minor amounts of oil or surfactant are used and a froth is formed by agitating or bubbling air through the suspension. The oily froth or foam is concentrated in mineral particles and can be skimmed off as shown schematically in Fig. XIII-4. 

Sorted plastic packaging materials are shipped, usually in bales, to processing plants to be converted to polymer resins. The bales are broken and the bottles sorted to ensure that only one type of polymer is further processed. Processing consists of chopping and grinding the bottles into flakes. These flakes are washed. Processing steps such as flotation are used to remove polymeric contaminants from the flakes (15,16). The flakes are melted and converted into pellets. 

The KDF Filter. The KDP filter (Pig. 23) (Amafilter, Holland) is based on the same principle as disk filters. It was developed for the treatment of mineral raw materials, like coal flotation concentrates or cement slurries, and can produce a filter cake of low moisture content at very high capacities, up... 

Soluble Salt Flotation. KCl separation from NaCl and media containing other soluble salts such as MgCl (eg, The Dead Sea works in Israel and Jordan) or insoluble materials such as clays is accompHshed by the flotation of crystals using amines as coUectors. The mechanism of adsorption of amines on soluble salts such as KCl has been shown to be due to the matching of coUector ion size and lattice vacancies (in KCl flotation) as well as surface charges carried by the soflds floated (22). Although cation-type coUectors (eg, amines) are commonly used, the utUity of sulfonates and carboxylates has also been demonstrated in laboratory experiments. 

Buoyancy. The low density, closed-ceUed nature of many ceUular polymers coupled with their moisture resistance and low cost resulted in their immediate acceptance for buoyancy in boats and floating stmctures such as docks and buoys. Since each ceU in the foam is a separate flotation member, these materials caimot be destroyed by a single puncture. 

The combination of stmctural strength and flotation has stimulated the design of pleasure boats using a foamed-in-place polyurethane between thin skins of high tensUe strength (231). Other ceUular polymers that have been used in considerable quantities for buoyancy appHcations are those produced from polyethylene, poly(vinyl chloride), and certain types of mbber. The susceptibUity of polystyrene foams to attack by certain petroleum products that are likely to come in contact with boats led to the development of foams from copolymers of styrene and acrylonitrUe which are resistant to these materials... 

The fine mica fraction is deslimed over 0.875—0.147-mm (80—100-mesh) Trommel screens or hydrocylcones, or is separated with hydrosi2ers. The deslimed pulp (<0.589 mm (—28 mesh)) of mica, feldspar, and quart2 is then fed to a froth flotation circuit where these materials are separated from each other either by floating in an acid circuit with rosin amine and sulfuric acid (2.5—4.0 pH), or an alkaline circuit (7.5—9.0 pH) with tall oil amine, goulac, rosin amine acetate, and caustic soda (see Eig. 2). 

The matte can be treated in different ways, depending on the copper content and on the desired product. In some cases, the copper content of the Bessemer matte is low enough to allow the material to be cast directly into sulfide anodes for electrolytic refining. Usually it is necessary first to separate the nickel and copper sulfides. The copper—nickel matte is cooled slowly for ca 4 d to faciUtate grain growth of mineral crystals of copper sulfide, nickel—sulfide, and a nickel—copper alloy. This matte is pulverized, the nickel and copper sulfides isolated by flotation, and the alloy extracted magnetically and refined electrolyticaHy. The nickel sulfide is cast into anodes for electrolysis or, more commonly, is roasted to nickel oxide and further reduced to metal for refining by electrolysis or by the carbonyl method. Alternatively, the nickel sulfide may be roasted to provide a nickel oxide sinter that is suitable for direct use by the steel industry. 

Generally, Httle is known in advance concerning the degree of homogeneity of most sampled systems. Uniformity, rarely constant throughout bulk systems, is often nonrandom. During the production of thousands of tons of material, size and shape distribution, surface and bulk composition, density, moisture, etc, can vary. Thus, in any bulk container, the product may be stratified into zones of variable properties. In gas and Hquid systems, particulates segregate and concentrate in specific locations in the container as the result of sedimentation (qv) or flotation (qv) processes. 

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