Uniform mixing

Typically, dry potassium nitrate is pulverized in a ball mill. Sulfur is milled into cellular charcoal to form a uniform mix in a separate ball mill. The nitrate and the sulfur—charcoal mix are screened and then loosely mixed by hand or in a tumbling machine. Magnetic separators may be used to ensure the absence of ferrous metals. The preliminary mix is transferred to an edge-mimer wheel mill with large, heavy cast iron wheels. A clearance between the pan and the wheels is required for safety purposes. The size of this gap also contributes to the density of the black powder granules obtained. Water is added to minimize dusting and improve incorporation of the nitrate into the charcoal. The milling operation requires ca 3 to 6 h. 

The shell-molding process, introduced in the United States in 1948, is an important market for phenoHc resins. In the original process, dry sand and powdered resin (6—8%) are blended. However, because of the high binder content and the difficulty in obtaining a uniform mix, precoating methods were developed. 

If a small amount (less than 5% of the blend) of a strong pigment is used as a component in a blend, it will be difficult to obtain sufficiently uniform mixing to avoid specking. It is preferable to use larger concentrations of a less intense pigment. 

The AIG is used to uniformly inject diluted ammonia into the reactor. Uniform mixing of the ammonia into the flue gas is necessary to maintain catalyst performance at its highest level and to minimize ammonia leakage (ammonia sHp) past the catalyst. 

When a process is continuous, nucleation frequently occurs in the presence of a seeded solution by the combined effec ts of mechanical stimulus and nucleation caused by supersaturation (heterogeneous nucleation). If such a system is completely and uniformly mixed (i.e., the product stream represents the typical magma circulated within the system) and if the system is operating at steady state, the particle-size distribution has definite hmits which can be predic ted mathematically with a high degree of accuracy, as will be shown later in this section. 

For these large tr values, eddy reflection has occurred repeatedly both at the ground and at the mixing height, so that the vertical expanse of the plume has been uniformly mixed through the mixing height, i.e., 1/L. 

Models which assume uniform mixing throughout the volume of a three-dimensional box are useful for estimating concentrations, especially for first approximations. For steady-state emission and atmospheric conditions, with no upwind background concentrations, the concentration is given by... 

Uniform mixing in the vertical to 1000 m and uniform concentrations across each puff as it expands with the square root of travel time are assumed. A 0.01 h transformation rate from SO2 to sulfate and 0.029 and 0.007 h" dry deposition rates for SO2 and sulfate, respectively, are used. Wet deposition is dependent on the rainfall rate determined from the surface obser% ation network every 6 h, with the rate assumed to be uniform over each 6-h period. Concentrations for each cell are determined by averaging the concentrations of each time step for the cell, and deposition is determined by totaling all depositions over the period. 

Uniform mixing The mixing of two or more fluids that ensures complete uniformity of the mix. 

Calculate the concentration of CO2 in the room after the fire extinguisher is emptied. Does it e.xceed the IDLH value Assume that the gas mi.xture in the room is uniformly mixed, that the temperature in the room is 300°C (warmed... 

The pistons therefore tend to separate, A under the pressure exerted by the gas [2], B under the pressure exerted by the gas [1], and motion ceases only when the pistons are in contact with the cylinder ends, and the gases are uniformly mixed. 

Hicks (H6) and Frazer and Hicks (F3) considered the ignition model in which exothermic, exponentially temperature-dependent reactions occur within the solid phase. Assuming a uniformly mixed solid phase, the one-dimensional unsteady heat-flow equation relates the propellant temperature, depth from the surface, and time by the nonlinear equation ... 

In a batch vessel, the question of good mixing will arise at the start of the batch and whenever an ingredient is added to the batch. The component balance, Equation (1.21), assumes that uniform mixing is achieved before any appreciable reaction occurs. This will be true if Equation (1.55) is satisfied. Consider the same vessel being used as a flow reactor. Now, the mixing time must be short compared with the mean residence time, else newly charged... 

Byproducts, such as methyltrichlorosilane (Mj), trimethylchlorosilane (M3), methyldichlorosilane (MH), and some residuals (R) having a boiling point above 70 C are also produced. One of the most efficient ways to prepare the active copper-silicon alloy is by the uniform mixing of CuCl and silicon particles. The following reaction takes place when the mixture is heated to the reaction temperature ... 

The crucible is kept rotating to maintain a uniform mixing and heat flow while the crystals are growing. 

Figure 1.52. Uniformly mixed kinetics model. q volume flow rate (m /s), Cj initial concentration (molal), 1 height (m), r radius (m), C concentration (molal), V volume of the system (m ).

The calculations were made based on the uniformly mixed precipitation kinetics model (Fig. 1.52) for one component and one dimensional system represented by Eq. (1-20). 

Determine the time required for the tracer to be nearly completely mixed throughout the vessel. Which criterion did you use for uniform mixing ... 

For conventional approach, 4 mL of methanol is mixed with 4 g of vegetable oil and catalyst concentration (NaOH) used in 0.5% of oil (Case I a stirrer is used for uniform mixing which consumes energy Case II heater is used for maintaining reflux conditions)... 

Ventilation rates were determined with a nitrous oxide tracer. The gas was released into room air. After allowing time for uniform mixing, the decay in concentration was followed using an infra-red gas analyser, type Miran-101 (Foxboro/Wilks Inc. USA). 

Drug particle size can also be a factor in mixing uniformity. When particles of different sizes are mixed, the smaller particles tend to travel or percolate downward. This tendency is a particular problem with low-dose drugs, where a small amount of drug is to be mixed with large amounts of diluents. In this situation, it is more difficult to achieve uniform mixing, and undesirable... 

The reactor flow pattern is that of an internal loop airlift with pneumatic mixing of both the liquid and the solid phases [61], the latter consisting in biofilm supported by granular solids. The reactor was assumed uniformly mixed. 

Since the fluid inside the vessel is uniformly mixed (and hence elements of fluid... 

Let a mass m of solute be dissolved in a liquid volume V in the first stirred tank, there being no solute in the other tanks. Let solute free liquid flow into the tank at a volumetric flow rate Q. Let liquid flow from the tank at a volumetric flow rate Q. If the liquid in the tank is uniformly mixed the discharge liquid contains a concentration of solute m/V which is the same as the solute concentration in the tank. 

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