Particle deagglomeration

Convection heat transfer is dependent largely on the relative velocity between the warm gas and the drying surface. Interest in pulse combustion heat sources anticipates that high frequency reversals of gas flow direction relative to wet material in dispersed-particle dryers can maintain higher gas velocities around the particles for longer periods than possible ia simple cocurrent dryers. This technique is thus expected to enhance heat- and mass-transfer performance. This is apart from the concept that mechanical stresses iaduced ia material by rapid directional reversals of gas flow promote particle deagglomeration, dispersion, and Hquid stream breakup iato fine droplets. Commercial appHcations are needed to confirm the economic value of pulse combustion for drying. 

In addition to their use as absorbents, hormite clays are used as rheological agents. When dispersed in water, their needle-like particles deagglomerate in proportion to the amoimt of energy applied and form a random colloidal lattice. 

In addition to their high absorptive eapacity hormite clays offer useful thickening properties. When dispersed in water they do not swell, as smectites do. Instead, their needle-like colloidal particles deagglomerate in proportion to the amoimt of shear applied and form a random colloidal lattice. This loosely cohesive structure thickens the water and imparts thixotropy, pseudoplasticity, and yield value. Because of their mechanically-based dispersion and colloidal structure building, hormite cl s are largely insensitive to the types and levels of acids, bases, and salts dissolved in the aqueous systems in which they are used. Since their dispersion is mechanically rather than ionically driven, as with smectites, they can be used in nonaqueous applications in much the same... 

Viscosity. Because a clump of particles contains occluded Hquid, the effective volume fraction of a suspension of clumps is larger than the volume fraction of the individual particles that is, there is less free Hquid available to faciHtate the flow than if the clumps were deagglomerated. The viscosity of a suspension containing clumps decreases as the system becomes deagglomerated. This method is not very sensitive in the final stages of deagglomeration when there are only a few small clumps left. 

In general, it appears that the Micromerograph, provided that frequent calibration checks are performed, is a good, reproducible instrument for size measurement. The operator time involved is less than with most other methods, and the calcns are not complicated. As in all sedimentation methods, only when the sample particles are spherical does the Stokes diameter that is measured become a measure of absolute particle size. Microscopic examination should be used to check on particle shape and the effect of deagglomeration... 

A fine cloud of drug particles is generated by deagglomerating the powder and diluting it with air, and... 

John, W., Particle-Surface Interactions Charge Transfer, Energy Loss, Resuspension, and Deagglomeration, Aerosol Sci. Technol., 23, 2-24 (1995). 

Screening Particle size reduction by mechanically-induced attrition through a screen (commonly referred to as milling or deagglomeration) Tumble Milling Particle size reduction by attrition, using grinding media... 

Mixing The reorientation of particles relative to one another to achieve uniformity or randomness. This process can include wetting of solids by a liquid phase, dispersion of discrete particles, or deagglomeration into a continuous phase. Heating and cooling via indirect conduction may be used in this operation to facilitate phase mixing or stabilization. 

The synthesis of Mn2+-doped CdS nanocrystals has been studied by several groups. In one such study (82), the doped CdS nanocrystals were prepared by simple mixing of ethylene glycol solutions of cadmium and manganese acetate with a solution of sodium sulfide, followed by washing with methanol and thermal treatment in triethyl phosphate to deagglomerate the particles. Mean... 

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