Size,mesh

In most inorganic chromatography, resins of 100 to 200 mesh size are suitable difficult separations may require 200 to 400 mesh resins. A flow rate of 1 mL cm min is often satisfactory. With HPEC columns, the flow rate in long columns of fine adsorbent can be increased by applying pressure. 

Dowex is the trade name of Dow resins X (followed by a numeral) is percent cross-linked. Mesh size (dry) are available in the range 50 to 100, 100 to 200, 200 to 400, and sometimes minus 400. 

Solid samples are separated by particle size using one or more sieves. By selecting several sieves of different mesh size, particulates with a narrow size range can be isolated from the solid matrix. Sieves are available in a variety of mesh sizes, ranging from approximately 25 mm to 40 )j,m. 

The Utah deposit is located in southwestern Utah near Cedar City. The iron ore deposits are of contact metamorphic origin. The cmde ore contains 35 to 65% iron, primarily in the form of magnetite and goethite. Mining is done by the open pit method. The cmde ore is cmshed, screened at —75 mm (—200 mesh size) and shipped as lump ore containing 54% iron. The ore is rescreened at the steel mill to produce lump ore (10—64 mm) for the blast furnace and sinter feed (0—10 mm) for the sinter plant. 

Miscellaneous Kilns. A U.S. kiln, the Fluo-Sohds, appears to be another vertical kiln type, but this is its only similarity. It operates on a different principle. It utilizes as kiln feed only a discrete granulation of 0.225—2.4 mm (65—8 mesh) sizes. DeHcately controlled by air and exhaust gas pressure, the kiln feed of granules is fluidized as a dense suspension. Because it is instmmented, this kiln can produce a very reactive lime at better than average thermal efficiency. The kiln, however, has limited utifity because the cost of obtaining the kiln feed with many hard, compact limestones is prohibitive. 

Physical forms Physical size, mm (mesh size) Derivation ... 

Umestone Sand. A discrete gradation of substantially 2.38—0.225 mm (8—65 mesh) size provides a versatile fine aggregate or sand for road mixtures, concrete, plaster, or any constmcfion use suppHed by siHca sand. The only disadvantage is that in many areas conventional sand is less cosdy. 

Industrial Fillers. Whiting is widely used ia paints as a filler and pigment extender. A high refiective white color is a requisite for paint. Both ultrafine and relatively coarse carbonate fillers ate iacorporated ia mbber products. The latter type of a nominal 0.074 mm (200 mesh) size is for iaexpensive mbber products. 

Economic Aspects. Lithium metal is available commercially in ingots, special shapes, shot, and dispersions. Ingots are sold in 0.11-, 0.23-, 0.45-, and 0.91-kg sizes. Special shapes include foil, wire, and rod. Lithium is available in hermetically sealed copper cartridges and in sealed copper tubes for use in treating molten copper and copper-base alloys. Shot is sold in 1.19—4.76 mm (16—4 mesh) sizes. Lithium dispersions (30% in mineral oil) of 10—50-p.m particle size are used primarily in organic chemical reactions. Dispersions in other solvents and of other size fractions can be suppHed. 

Values given are typical of iron powder samples. Numbers in parentheses represent mesh sizes. 

AU processed material is screened to return the coarse fraction for a second pass through the system. Process feed rates are matched to operating variables such as rpm speed and internal clearances, thus minimizing the level of excess fines (—200 mesh (<0.075 mm mm)). At one installation (3) the foUowing product size gradation of total smaller than mesh size (cumulative minus) was obtained ... 

Second-pass catalyst pellets need screening less frequendy because the first converter-pass catalyst bed acts as a filter for the rest of the converter. Typical screening losses range from 10—15% of the catalyst bed per screening. Screening losses depend on screen mesh size and catalyst hardness, as well as on screening rate. 

Calcium carbonate is one of the most common filler/extenders used in the paint and coatings industry. Consumer and contractor paint formulas can include products from submicrometer size to coarse mesh sizes. The main function of calcium carbonate in paint is as a low cost extender. It is also used to improve brightness, appHcation properties, stabiHty, and exposure resistance. Coarse products help to lower gloss and sheen or even provide textured finishes. The selection of product type and particle size is deterrnined by the desired performance and cost of the coating. 

Product particle sizes vary from standard size of 6/14 mesh—U.S. Std. Sieves to mini-size granules of 10/16 mesh—U.S. Std. Sieves for small particle blends, to micro-size granules of 14/35-U.S. Std. Sieves for use on golf course tees and greens. Approximate mm corresponding to mesh sizes are 6 mesh/3.36 mm 10 mesh /2 mm 35 mesh/0.5 mm. 

Sometimes the domain is semi-infinite, as in boundaiy layer flow. The domain can be transformed from the x domain (O-oo) to the T domain (1-0) using the transformation T = exp ( ). Another approach is to use a variable mesh, perhaps with the same transformation. For example, use T = exp (— x) and a constant mesh size in T the value of is found experimentally. Still another approach is to solve on a finite mesh in which the last point is far enough away that its location does not influence the solution (Ref. 59). A location that is far enough away must be found by trial and error. 

Alumina (AfOf. Alumina is produced by calcining either bauxite or aluminum hydroxide in rotary Idlns at temperatures from 1250 to 1600 K. In obtaining the highest-purity alumina, the bauxite is digested with alkah to remove impurities the resultant aluminum hydroxide [AlgfOH) ], of approximately 200-mesh size, is then calcined in rotaiy Idlns at 1350 K. 

The data for a plot like Fig. 18-60 are easily obtained from a screen analysis of the total crystal content of a known volume (e.g., a liter) of magma. The analysis is made with a closely spaced set of testing sieves, as discussed in Sec. 19, Table 19-6, the cumulative number of particles smaller than each sieve in the nest being plotted against the aperture dimension of that sieve. The fraction retained on each sieve is weighed, and the mass is converted to the equivalent number of particles by dividing by the calculated mass of a particle whose dimension is the arithmetic mean of the mesh sizes of the sieve on which it is retained and the sieve immediately above it. 

In industrial practice, the size-distribution cui ve usually is not actually construc ted. Instead, a mean value of the population density for any sieve fraction of interest (in essence, the population density of the particle of average dimension in that fraction) is determined directly as AN/AL, AN being the number of particles retained on the sieve and AL being the difference between the mesh sizes of the retaining sieve and its immediate predecessor. It is common to employ the units of (mm-L)" for n. 

However, separation between resistance levels of 1000 to 300 kH may be marginal. A typical application of conductivity sorting is the separation of massive ilmenite from anorthosite. Both are compact rocks, but ilmenite is a good electrical conductor, whereas anorthosite is an insulator. The dimensions and operating information for the Sor-tex CS-03 conductivity sorter, which is capable of processing up to about 25,000 kg/h (27.5 tons/h) of 0.05-to 0.15-in mesh size (2 to 6 in), are given in Table 19-4. 

Product grade Percent retained by weight for mesh size 1978 cost... 

Particle size mesh size less than 1978 cost range... 

Sieves are often referred to by their mesh size, which is the number of wires per hnear unit. The U.S. Standard Sieve Series as described by the American Society of Testing and Materials (ASTM) document E-11-87 Standard Specification for Wire-cloth Sieves for Testing Purposes addresses sieve opening sizes from 20 [Lm (635 mesh) to 125 mm (5.00 in). Electroformed sieves with square or round apertures and tolerances of 2 [Lm, are also available. 

The definitions coarsely chopped to finely powdered , which formerly in the pharmacopoeias were given as mesh sizes, are mostly nowadays indicated without such a requirement in the DAB 10, V. 4.N6, only coarsely chopped (4000 to 2800 sieve), finely chopped (2000 sieve), and powdered (710 to 180 sieve) are distinguished. The wide particle-size ranges have rightly been criticized [1, 2], partly on the basis of extensive investigations. 

What is the settling velocity in cm/sec in air at 25°C and 1 atmosphere for a 100 mesh size spherical particle, i.e., one which just passes through the opening in the sieve (specitlc gravity = 2.0) ... 

The simplest diffraction measurement is the determination of the surface or overlayer unit mesh size and shape. This can be performed by inspection of the diffraction pattern at any energy of the incident beam (see Figure 4). The determination is simplest if the electron beam is incident normal to the surface, because the symmetry of the pattern is then preserved. The diffraction pattern determines only the size and shape of the unit mesh. The positions of atoms in the surface cannot be determined from visual inspection of the diffraction pattern, but must be obtained from an analysis of the intensities of the diffracted beams. Generally, the intensity in a diffracted beam is measured as a fimction of the incident-beam energy at several diffraction geometries. These intensity-versus-energy curves are then compared to model calculations. ... 

A reduction in the amount of tin lowers the yield. Best results are obtained using powdered tin of between 100 and 200 mesh size. Use of tin coarser than 100 mesh results in the presence of unchanged anisoin, while tin finer than 200 mesh tends to conglomerate, causing lower yields. The checkers used tin obtained from E. H. Sargent Co., Chicago, labeled 200 mesh. 

Mesh Size Nominal Particle Retention % Open Area... 

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