Mixing, dry powders

Dried or freeze dried samples can be extracted with water-immiscible solvents such as EtOAc or diethyl ether. For quantitative extraction, dried samples are preferably rehydrated at different times for example, 5 to 10 min for dried mangoes, 30 min for lyophihzed red peppers and pasta. Rehydration is followed by extraction with acetone or MeOH. Bixin and norbixin from a mix dry powder of annatto and com can quantitatively be extracted with MeOH followed by acetone. In order to improve pigment recovery, extruded foods require pre-digestion with enzymes to liberate the pigment from the matrix. ... 

The use of a diesel-based concentrate with hydroxypropylguar gum has been evolved from the batch-mixed dry powder types [778], The application of such a concentrate reduces system requirements. Companies can benefit... 

In summary, the second option, which is to perform a dry blend in a fluidized bed granulator in a very short time followed by spraying the granulation liquid onto the mixed dry powders, is recommended as the first choice for the manufacture of low-dose products. 

For Love mix dried, powdered Rose petals, Vervain,... 

High Shear Mixing Dry Powders and Resin. High shear mixing is required for achieving fiber and film quality dispersion. The shear impacts the pigment particle onto the surface of the resin and waxes. The air on the surface is... 

These mixers tend to be better at mixing dry powders in a horizontal plane than the vertical. Lack of vertical mixing may require the materials to be dumped and returned to the bowl to obtain an acceptable dry mix. Reduced vertical mixing... 

Mix together in a 250 ml. flask carrying a reflux condenser and a calcium chloride drying tube 25 g. (32 ml.) of freshly-distilled acetaldehyde with a solution of 59-5 g. of dry, powdered malonic acid (Section 111,157) in 67 g. (68-5 ml.) of dry pyridine to which 0-5 ml. of piperidine has been added. Leave in an ice chest or refrigerator for 24 hours. Warm the mixture on a steam bath until the evolution of carbon dioxide ceases. Cool in ice, add 60 ml. of 1 1 sulphuric acid (by volume) and leave in the ice bath for 3-4 hours. Collect the crude crotonic acid (ca. 27 g.) which has separated by suction filtration. Extract the mother liquor with three 25 ml. portions of ether, dry the ethereal extract, and evaporate the ether the residual crude acid weighs 6 g. Recrystallise from light petroleum, b.p. 60-80° the yield of erude crotonic acid, m.p. 72°, is 20 g. 

If either dry powders or inverse emulsions are not properly mixed with water, large lumps of polymer form that do not dissolve. This not only wastes material, but can also cause downstream problems. This is especially tme for paper where visible defects may be formed. Specialized equipment for dissolving both dry polymers and inverse emulsions on a continuous basis is available (22,23). Some care must be taken with regard to water quaUty when dissolving polyacrylamides. Anionic polymers can degrade rapidly in the presence of ferrous ion sometimes present in well water (24). Some cationic polymers can lose charge by hydrolysis at high pH (25). 

In the case of poly(vinyl chloride) plastics, the FWA is mixed dry with the PVC powder before processing or dissolved in the plasticising agent (see Vinyl polymers). Polystyrene, acrylonitrile—butadiene—styrene (ABS), and polyolefin granulates are powdered with FWA prior to extmsion (2,78) (see... 

Iron Browns. Iron browns are often prepared by blending red, yellow, and black synthetic iron oxides to the desired shade. The most effective mixing can be achieved by blending iron oxide pastes, rather than dry powders. After mixing, the paste has to be dried at temperatures around 100°C, as higher temperatures might result in the decomposition of the temperature-sensitive iron yellows and blacks. Iron browns can also be prepared directiy by heating hydrated ferric oxides in the presence of phosphoric acid, or alkaU phosphates, under atmospheric or increased pressure. The products of precipitation processes, ie, the yellows, blacks, and browns, can also be calcined to reds and browns. 

Two or more soHd catalyst components can be mixed to produce a composite that functions as a supported catalyst. The ingredients may be mixed as wet or dry powders and pressed into tablets, roUed into spheres, or pelletized, and then activated. The promoted potassium ferrite catalysts used to dehydrogenate ethylbenzene in the manufacture of styrene or to dehydrogenate butanes in the manufacture of butenes are examples of catalysts manufactured by pelletization and calcination of physically mixed soHd components. In this case a potassium salt, iron oxide, and other ingredients are mixed, extmded, and calcined to produce the iron oxide-supported potassium ferrite catalyst. 

Dental Stones. Dental stones, produced from gypsum, are sold as dry powders in sealed containers. They are prepared for use by mixing with water, in proportions recommended by the manufacturer. 

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