Blending, suspending

Wettable powders are prepared by blending the toxicant in high concentration, usually from 15 ndash 95%, with a dust carrier such as attapulgite which wets and suspends properly in water. One to two percent of a surface-active agent usually is added to improve the wetting and suspensibiUty of the powder. Sprays of wettable powders are used widely in agriculture because of their relative safety to plants. 

The required soHds are suspended in a wax—emoUient blend at about 60 to 80°C and milled. The Hquid suspension is then cooled to about 55°C, and the more volatile ingredients are added. The mass is placed into containers, which are commonly provided with a threaded shaft for raising or lowering the product. 

Most antiperspirant sticks are molded. Sticks dominate in the U.S. market, whereas lotion and cream antiperspirants are preferred in Europe. Stick antiperspirant products may include suspending agents, coupling agents to wet the antiperspirant chemical (about 20—25%), and emoUients. The blend is prepared at about 65°C and poured at about 55°C. Antiperspirant (64) and deodorant (65) compositions have been pubHshed. 

In hair coloring a light ash blond shade may require as Httie as 0.5—1% of intermediates, whereas a tme black may require up to about 5%. In principle, the formulator blends precursors that yield red, blue, and yellow dyes. The base in which the components are dissolved or suspended is similar to that used in simple bleaches and may include alkanolamides, various types of surfactants, thickening agents, and solvents. Removal of undesirable dyes is achieved by treating the discolored hair with a powerful reductant of the sulfite family. 

Axial-tlow impellers rnav also be mounted near the bottom of the cylindrical wall of a cssel as shown in Fig, 18-10, Such side-entering agitators are used to blend low- iscositv fluids [<(), Pa-s (100 cP)] or to keep slowly settling sediment suspended in tanks as large as some 4000 rn (1(P gal). Mixing of paper pulp i.s often carried out by sideentering propellers. 

Polymers are suspended as microparticles in the latex and interactions between these microparticles are prevented by the presence of adsorbed suspending agent and soap molecules. Blending results in a random suspension of dissimilar particles in the mixture of latexes, each unaffected by the other. Rate of flocculation depends entirely on the stabilizer and not on the polymer characteristics as such. Coagulated mass contains an intimate mixture of the polymers. Acrylonitrile butadiene styrene (ABS) polymers [23-25] may be prepared by this method. 

Class Q Blending Q Dissolving Q Suspending Solids Q Cooking Q Emulsifying Q Heat Tronsfer Q Gas Dispersion Time Req d ... 

Operations such as blending, solids-suspension, dissolving, heat transfer and liquid-liquid extraction are typical of systems requiring high flow relative to turbulence, while gas-liquid reactions and some liquid-liquid contacting require high turbulence relative to flow. The case of (1) 100% of suspension—requires head to keep particles suspended and (2) 100% uniformity of distribution of particles—requires head for suspension plus flow for dis-tiibution. 

In a typical batch suspension process (Figure 12-5), styrene is suspended in water by agitation and use of a stabilizer. The polymer forms beads. The bead/water slurry is separated by centrifugation, dried, and blended with additives. 

Mixers are devices that blend combinations of liquids and solids into a homogenous product. They come in a variety of sizes and configurations designed for specific applications. Agitators provide the mechanical action required to keep dissolved or suspended solids in solution. 

In another study of the physical behavior of soap-LSDA blends, Weil and Linfield [35] showed that the mechanism of action of such mixtures is based on a close association between the two components. In deionized water this association is mixed micellar. Surface tension curves confirm the presence of mixed micelles in deionized water and show a combination of optimum surface active properties, such as low CMC, high surface concentration, and low surface concentration above the CMC. Solubilization of high Krafft point soap by an LSDA and of a difficulty soluble LSDA by soap are related results of this association. Analysis of dispersions of soap-LSDA mixtures in hard water shows that the dispersed particles are mixtures of soap and LSDA in the same proportion as they were originally added. These findings are inconsistent with the view that soap reacts separately with hard water ions and that the resulting lime soap is suspended by surface adsorption of LSDA. The suspended particles are responsible for surface-active properties and detergency and do not permit deposits on washed fabric unlike those found after washing with soap alone. 

Additives and mixtures to reduce or prevent lost circulation Density-increasing or weighting agents Free water control and solid suspending agents Spacers and chemical washes or preflushes Specialty cement blends... 

Pretreatment is required to remove suspended solids from the concentrate and to reduce the likelihood of precipitates forming in the injection zone. Solids may be present in the concentrate, especially when filter backwash is blended with the concentrate prior to injection. Pretreatment costs include filtration of the solids and chemicals for pH adjustment (Mickley 2006). 

Mixed fertilizer (subcategory G) treatment technology consists of a closed-loop contaminated water system, which includes a retention pond to settle suspended solids. The water is then recycled back to the system. There are no liquid waste streams associated with the blend fertilizer (subcategory G) process, except when liquid air scrubbers are used to prevent air pollution. Dry removals of air pollutants prevent a wastewater stream from being formed. 

Agitators capable of level 6 will Blend miscible fluids to uniformity, if specific gravity differences are less than 0.6 and if the viscosity of the most viscous is less than 10,000 times the viscosity of the other Suspend trace solids (<2%) with settling rates of 2-4 ft/min Produce surface rippling at lower viscosities. 

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