Mixing electrostatic charge

Full scale mixing studies were conducted without incident using 100, 250, 500, and 1,000 pound batch sizes. Electrostatic charge generation during the blending cycle was several orders of magnitude below that required for initiation. 

There was no significant damage to equipment in the fire tests, and it was demonstrated that a Jet Airmix mixer may safely handle the mixing of RP formulations on a routine basis. Since a high risk of fire is always associated with any method of transfer of RP, a pneumatic conveying system [dynamic air, two phase positive pressure transfer system was evaluated to load RP into the Jet Airmix mixer. Electrostatic charge measurements were minimal and indicated the system was satisfactory to load the blender. 

Treatment of the isomeric l,3a,4,6a- (220) and 1,3a,6,6a- (91) dibenzotetraazapentalenes with mixed acid or fuming nitric acid forms z-TACOT (225) and y-TACOT (231), respectively. 438 z xaCOT (225) and y-TACOT (231) are highly insensitive to impact and electrostatic charge and exhibit extremely high thermal stability (ignition temperature 494 °C, DTA curve 354 °C). 

The number of forces separating the particles is smaller. Repulsive forces act between particles with the same electrostatic charge. The mixing of fiuids leads to the development of shear forces, which try to separate the particles. The maximum hydrodynamic force acting on spheres in a uniform shear field can be expressed as [22,24] ... 

Polyurethanes find an application where they dissipate electrostatic charges generated in rollers and items such as chute liners. There are two main routes to obtain these properties. The classical method is to add conductive graphite or fine metal to the polyurethane. The major disadvantage is the high loading of the material, which reduces the physical properties. The viscosity of the mix is also drastically increased, and nonuniform mixing is often the result. The alternative is to use an anionic or cationic antistatic... 

Staniforth JN, Rees JE. 1982. Electrostatic charge interactions in ordered powder mixes. J. Pharm. Pharmac. 34 69 76. 

The problem with mixing hydrocolloids is that if the pH is wrong then the entire system becomes unstable. The stability of the hydrocolloid in solution depends on the electrostatic charge on the molecules, and anything that neutralises that charge is likely to bring the material out of solution. 

Properties Affecting Solids Mixing Wide differences among properties such as particle-size distribution, density, shape, and surface characteristics (such as electrostatic charge) may mane blending very difficult. In fact, the properties of the ingredients dominate the mixing operation. The most commonly observed characteristics of solids are as follows ... 

Method of Adding Liquids When the addition of liquids may be desirable (see Dust Formation and Electrostatic Charge ), this should be considered when designing the mixing system rather than hastily improvised. The purpose of the liquid should be considered, whether for (1) dust suppression, (2) product, or (3) heating and cooling. If a viscous liquid must be well distributed, this requirement should be considered when choosing the mixer. 

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