Particles disks

Solid-phase antibody (particles, disks, tubes, gel entrapment, polymerized antibody)... 

Since the optimal pore size depends on the application, it is important to have control over the porosity of materials. Novel methods of fabricating a porous matrix include using a 3D paraffin mold to create a spherical pore network (Ma and Choi, 2001) using sugar particles, disks, and fibers to produce a variety of controlled porous PLLA structures (Zhang and Ma, 2000) and using high-... 

This can be observed in Figure 12.2, which shows the surface area-to-volume ratio (A/V) as a function of the aspect ratio (a = l/d) of a cylindrical particle (disk/platelet-like or cylinder/fiber-like), for a given particle volume. Values of l/d < 1 correspond to platelet-like particles, while l/d > 1 correspond to rod-like particles. It can be seen that A/V increases faster for platelet-like particles than for rod-like particles with respect to their aspect ratio [6]. Hence, for an equivalent volume of particles and for the same aspect ratio, platelet-like particles have higher contact surfaces, which makes them more difficult to be dispersed. 

Crushing and grinding uses mechanical force to break larger particles into smaller ones. A variety of tools are used depending on the particle s size and hardness. Large particles are crushed using jaw crushers capable of reducing particles to diameters of a few millimeters. Ball mills, disk mills, and mortars and pestles are used to further reduce particle size. 

Ore samples are analyzed for %w/w Ni. A jaw crusher is used to break the original ore sample into smaller pieces that are then sieved into 5 size fractions. A portion of each fraction is reduced in size using a disk mill and samples taken for analysis by coning and quartering. The effect of particle size on the determination of %w/w Ni is evaluated. 

Figure 10.13 shows such plots of z versus D/X, where D is r for random coils, R for spheres and disks, and L for rods. More detailed theories permit these curves to be extended to larger values of than is justified by consideration of Eq. (10.97) alone. In the following example we illustrate an application of this simple method for estimating particle dimensions. 

Venturi scmbbers can be operated at 2.5 kPa (19 mm Hg) to coUect many particles coarser than 1 p.m efficiently. Smaller particles often require a pressure drop of 7.5—10 kPa (56—75 mm Hg). When most of the particulates are smaller than 0.5 p.m and are hydrophobic, venturis have been operated at pressure drops from 25 to 32.5 kPa (187—244 mm Hg). Water injection rate is typicaUy 0.67—1.4 m of Hquid per 1000 m of gas, although rates as high as 2.7 are used. Increasing water rates improves coUection efficiency. Many venturis contain louvers to vary throat cross section and pressure drop with changes in system gas flow. Venturi scmbbers can be made in various shapes with reasonably similar characteristics. Any device that causes contact of Hquid and gas at high velocity and pressure drop across an accelerating orifice wiU act much like a venturi scmbber. A flooded-disk scmbber in which the annular orifice created by the disc is equivalent to a venturi throat has been described (296). An irrigated packed fiber bed with performance similar to a... 

Most continuous vacuum filters are the constant pressure type. Their main use is in dewatering concentrated slurries such as concentrates. They belong to three classes the disk, dmm, and horizontal filters. Disk, and to a lesser extent, dmm filters, are the mainstay for most final dewatering. These filters remove most fine particles from a process stream. 

Processing Chip Screen Rejects. Overlong chips are usually reprocessed in a smaller version of the disk-type roundwood chipper. Overthick chips are reprocessed in a chip sheer. The product from these reprocessing operations returns to the main chip flow ahead of the screens (see Eig. 10). The fines are sent to a hog boiler as fuel, or else rescreened. Pin chips are metered back into the main chip flow or sent to a fine-particle pulping system. 

Unvulcanized Latex and Latex Compounds. A prime consideration has to be the fluid-state stabihty of the raw latex concentrate and hquid compound made from it. For many years, the mechanical stabihty of latex has been the fundamental test of this aspect. In testing, the raw latex mbber content is adjusted to 55% and an 80 g sample placed in the test vessel. The sample is then mechanically stirred at ultrahigh speed (ca 14,000 rpm) by a rotating disk, causing shear and particle cohision. The time taken to cause creation of mbber particle agglomerates is measured, and expressed as the mechanical stabihty time (MST). 

Fig. 3. Sepaiation in a disk centrifuge, where X is the initial position of the particle. Other terms are defined in the text.

Here again an equation is estabUshed (2) to describe the trajectory of a particle under the combined effect of the Hquid transport velocity acting in the x-direction and the centrifugal settling velocity in thejy-direction. Equation 13 determines the minimum particle size which originates from a position on the outer radius, and the midpoint of the space, between two adjacent disks, and just reaches the upper disk at the inner radius, r. Particles of this size initially located above the midpoint of space a are all collected on the underside of the upper disk those particles initially located below the midpoint escape capture. This condition defines the throughput, for which a 50% recovery of the entering particles is achieved. That is,... 

ScroU centrifuges discharge soHds continuously and usuaUy drier than disk and imperforate batch types. GeneraUy disk centrifuges have the highest values of Z or for a given size and therefore the best abUity to coUect fine particles at a high rate. 

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