Frothing foam

Schaum-bestflndigkeit, /. foam-holding capacity. -bier, n. foaming beer, -bildner, m. frothing agent, foamer. -bildtmg. /. formation of foam or froth, -blaae, /. bubble, -brecher, m. foam breaker, froth killer, schaumen, v.i. froth, foam (of wine, etc.) sparkle, fizz (of soap) lather. — v.t. skim, scum. 

Frothers are surfactants that contribute stability to the froth (foam) so that it will last long enough for solely mechanically-entrained particles to fall back into the pulp phase before the froth is skimmed. Frothers are frequently nonionic surfactants, such as cresol. Frothers may also aid the particle-bubble attachment process. Typical frothers include a variety of alcohols including a-terpineol (pine oil), cresol, polypropylene glycols, short-chain alcohols, and methylisobutylcarbinol (MIBC). 

The name tungsten is taken from the Swedish phrase that means heavy stone. In some parts of the world, the element is still called by another name, wolfram. This name comes from the German expression Wolf rahm, or wolf froth (foam). The element s chemical symbol is taken from the German name rather than the Swedish name. 

Delta-Therm . [Flexible Prods.] Rigid polyurethane systems for dispensing froth foams through pressurized equip. for sandwich panel cotriers/freezers, trucks, tanks, lupeline, boats. 

Process Industries Foam blankets on electroplating baths Sewage treatment effluent foams Mineral or oil flotation froths Foam fractionation Pulping black liquor foam... 

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. 

The importance of the thin film between the mineral particle and the air bubble has been discussed in a review by Pugh and Manev [74]. In this paper, modem studies of thin films via SFA and interferometry are discussed. These film effects come into play in the stability of foams and froths. Johansson and Pugh have studied the stability of a froth with particles. Small (30-/ m), moderately hydrophobic 6c = 65°) quartz particles stabilized a froth, while more hydrophobic particles destabilized it and larger particles had less influence [75]. 

Place 84 g. of iron filings and 340 ml. of water in a 1 - 5 or 2-litre bolt-head flask equipped with a mechanical stirrer. Heat the mixture to boiling, stir mechanically, and add the sodium m-nitrobenzenesulphonate in small portions during 1 hour. After each addition the mixture foams extensively a wet cloth should be applied to the neck of the flask if the mixture tends to froth over the sides. Replace from time to time the water which has evaporated so that the volume is approximately constant. When all the sodium salt has been introduced, boU the mixture for 20 minutes. Place a small drop of the suspension upon filter paper and observe the colour of the spot it should be a pale brown but not deep brown or deep yellow. If it is not appreciably coloured, add anhydrous sodium carbonate cautiously, stirring the mixture, until red litmus paper is turned blue and a test drop upon filter paper is not blackened by sodium sulphide solution. Filter at the pump and wash well with hot water. Concentrate the filtrate to about 200 ml., acidify with concentrated hydrochloric acid to Congo red, and allow to cool. Filter off the metanilic acid and dry upon filter paper. A further small quantity may be obtained by concentrating the mother liquid. The yield is 55 g. 

In other surfactant uses, dodecanol—tetradecanol is employed to prepare porous concrete (39), stearyl alcohol is used to make a polymer concrete (40), and lauryl alcohol is utilized for froth flotation of ores (41). A foamed composition of hexadecanol is used for textile printing (42) and a foamed composition of octadecanol is used for coating polymers (43). On the other hand, foam is controUed by detergent range alcohols in appHcations by lauryl alcohol in steel cleaning (44), by octadecanol in a detergent composition (45), and by eicosanol—docosanol in various systems (46). 

The product contains 12.6% phosphoms and has an OH number in the 450 mg KOH/g range. Fyrol 6 is used to impart a permanent Class 11 E-84 flame spread rating to rigid foam for insulating walls and roofs. Particular advantages are low viscosity, stabiHty in polyol—catalyst mixtures, and outstanding humid aging resistance. Fyrol 6 is used in both spray foam, froth, pour-in-place, and slab stock. 

The foam forming iagredients are carefully metered to obtain the proper ratio of reactants, thoroughly mixed by either mechanical or impingement means, then appHed as a Hquid, a spray, or a froth with subsequent expansion and cuiing. 

L tex Foa.m Rubber. Latex foam mbber was the first ceUular polymer to be produced by frothing. (/) A gas is dispersed in a suitable latex 2) the mbber latex particles are caused to coalesce and form a continuous mbber phase in the water phase (7) the aqueous soap film breaks owing to... 

Froth flotation (qv) is a significant use of foam for physical separations. It is used to separate the more precious minerals from the waste rock extracted from mines. This method reHes on the different wetting properties typical for the different extracts. Usually, the waste rock is preferentially wet by water, whereas the more valuable minerals are typically hydrophobic. Thus the mixture of the two powders are immersed in water containing foam promoters. Also added are modifiers which help ensure that the surface of the waste rock is hydrophilic. Upon formation of a foam by bubbling air and by agitation, the waste rock remains in the water while the minerals go to the surface of the bubbles, and are entrapped in the foam. The foam rises, bringing... 

Foam Products. Latices are made into foams for use in cushioning appHcations. The latices are frothed with air and then chemically coagulated for thick appHcations, or heated to induce coagulation for thinner appHcations. The latter method allows for infinite pot life during production (see Foamed plastics). 

Nonstabilized foams are referred to as froths froth-bonded fabrics are similar in properties to some saturation-bonded nonwovens. Typical foams used as nonwoven binder solutions have a consistency similar to shaving cream. AppHcation methods include knife-edge layering onto a horizontal web surface followed by vacuum penetration, and saturation and penetration of a vertical web surface using a horizontal-nip pad. Drying and curing is carried out in ovens, dmm dryers, or steam cans. 

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