Solid particle density

After determining the relevant physical properties (i.e., particle size, solids particle density and bulk density), the next step is to evaluate some of the existing techniques of powder classification. 

Group D products generally are of large particle size and/or very high solids particle density. In some respects, fluidization behavior is similar to Group B, although higher gas velocities are required for fluidization. 

Subsequently, simulations are performed for the air Paratherm solid fluidized bed system with solid particles of 0.08 cm in diameter and 0.896 g/cm3 in density. The solid particle density is very close to the liquid density (0.868 g/ cm3). The boundary condition for the gas phase is inflow and outflow for the bottom and the top walls, respectively. Particles are initially distributed in the liquid medium in which no flows for the liquid and particles are allowed through the bottom and top walls. Free slip boundary conditions are imposed on the four side walls. Specific simulation conditions for the particles are given as follows Case (b) 2,000 particles randomly placed in a 4 x 4 x 8 cm3 column Case (c) 8,000 particles randomly placed in a 4 x 4 x 8 cm3 column and Case (d) 8,000 particles randomly placed in the lower half of the 4x4x8 cm3 column. The solids volume fractions are 0.42, 1.68, and 3.35%, respectively for Cases (b), (c), and (d). 

The solid used in this work was silica gel of two different mean particle diameters. The fine silica gel ranged between 0.0058 to 0.0304 cm., and the coarser between 0.020 to 0.050 cm. in particle diameters. The mean particle diameters were 0.0125 cm. and 0.035 cm. respectively. Minimum fluidization velocities were 0.4113 cm/sec. and 1.67 cm/sec. respectively for the small and big particle diameters.Solid particle density was 1.25 g/cm. ... 

Describe the steady-state distribution of l-/xm diameter clay particles and 0.01 -/un diameter clay particles in still water. For each particle size, calculate the depth above the bottom of the water column at which the particle concentration is one-half the particle concentration at the bottom. Assume a kinematic viscosity of water of 0.013 cm2/sec at 50°F and a solid particle density of 2.6 g/cm3. 

The internal area A, is unknown but the total surface area Sg and the solid particle density Ps can be measured. Then,... 

E. Solid particles with significant density difference Ns, = = 2 + 0.44( YnV" [E] Use log mean concentration difference. Nsi, standard deviation 11.1%. i>sijp calculated by methods given in reference. [118]... 

Static This is a dense bed of solids in which each particle rests upon another at essentially the settled bulk density of the solids phase. Specifically, there is no relative motion among solids particles (Fig. 12-26). 

Types of Solids Geldart [Fowder TechnoL, 7, 285-292 (1973)] has characterized four groups of solids that exhibit different properties when fluidized with a gas. Figure 17-j shows the division oi the classes as a function of mean particle size, d,, Im, and densitv difference, (p, — P/ ), g/cm, where p, = particle density and p = fluid density... 

FIG. 17-2 Schematic phase diagram in the region of upward gas flow. W = mass flow solids, lh/(h fr) E = fraction voids Pp = particle density, Ih/ft Py= fluid density, Ih/ft Cd = drag coefficient Re = modified Reynolds uum-her. (Zenz and Othmei Fluidization and Fluid Particle Systems, Reinhold, New York, 1960. )... 

There is a gradual transition from particulate setthug into the zone-settling regime, where the particles are constrained to settle as a mass. The principal characteristic of this zone is that the setthug rate of the mass, as observed in batch tests, will be a function of its solids concentration (for any particular condition of flocculation, particle density, etc.). 

The control of processes involving the treatment of solids generally requires means for careful samphng and analysis of solids and slurries at various points in an operation. Unlike liquids, particulate solids are not homogeneous. The composition of individual particles will vaiy with particle size and particle density. It follows that care must be... 

Setthng rates of solid particles become progressively slower as the viscosity or density of the fluid medium increases. 

Feed Preparation and Feed Size The ability to achieve a separation of different solid particles on the basis of density, as in all physical separation, depends on the degree to which the particles are liberated (detached) from each other. Liberation can be achieved by breaking the material in a manner that causes it to fracfure and free the individual grains of the constituents to be recovered. The degree of separation that can be realized by the dense-media process will depend on the degree of hberation of the individual grains. 

FIG. 20-71 Classification of agglomeration processes by agitation intensity and compaction pressure. Relative density is with respect to primary particle density and equals (1 — e) where e is the solid volume fraction. Reprinted from Granulation and Coating Technologies for High-Value-Added Industties, Ennis and Litster (1996) with permission of E G Associates. All rights reserved. 

Density (solid particle) Design of treatment or Displacement... 

Particle density, Pp, is the density of a particle including the pores or voids within the individual solids. It is defined as the weight of the particle divided by the volume occupied by the entire particle. Sometimes this is referred to as the material s apparent density. 

Pf = density of liquid filling the solid particle pores... 

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