Sieve analysis particle separation

SIEVE ANALYSIS Determination of the proportions of particles lying within certain size ranges in a granular material by separation on sieves of different size openings. 

Sieving n. Separation ofa mixture of varioussized particles, either dry or suspended in a liquid, into two or more portions, by passing through screens of specified mesh sizes. See sieve analysis. Also known as screening. 

Particle size analysis include separation by sieving, sedimentation in a liquid or in air, sedimentation by means of a centrifuge, air separation, optical and X-ray observation of particles moved through a slot by means of a gas or liquid stream. In the latter case also the change of the electrical resistance may be observed. Image analysis of a powder distributed on a plain can be made. 

Figure 10 The granule growth of the one of the batch. Each dot (.) shows the data point for the particle mean size measured from the surface image information. Each numbered dot corresponds to the numbered surface images. Additionally, three end-point data points and images are shown together with three replicate data points from end-point sieve analysis (.). The spraying and drying phases of the process are separated with a dashed line. (From Ref. 33.)...

The test method used to determine the particle size and particle size distribution employs a series of sieves with various opening sizes. The material is simply poured from the top, allowed to pass through a series of sieves, and collected at the bottom. The quantity of material retained on each sieve is determined by weighing the sieves before and after the test. A shaker is employed to facilitate separation of various-sized particles. Figure 10-6 illustrates a typical setup for sieve analysis. 

The simplest and the most common method of separating mixtures exclusively by size alone is to make a screen analysis using testing sieves. A set of standard screens is arranged serially in a stack, with the smallest mesh at the bottom and the largest at the top. The analysis is carried out by placing the sample on the top screen. The stack is agitated manually or mechanically for a definite period. The particles retained on each screen are removed... 

Another possible application using the hierarchical nature of the wrinkles has been discussed by Efimenko and coworkers [46], They treated a mechanically stretched PDMS sheet with UV-ozone in order to create a stiff surface layer. A detailed analysis with AFM and profilometry of the wrinkles after releasing the strain showed that the wrinkling patterns are hierarchical themselves. They observed up to five generations of different wavelengths with different periodicities. These features made so structured surfaces valuable candidates for separate colloidal particles of different sizes by acting as a micro fluidic sieve. A suspension... 

In the above experiment involving five size fractions the rate curves for Cs uptake by each ion-exchanger fraction was not determined experimentally. This formidable task would have required several interruptions of the kinetic experiment after given periods of time, followed by reproducible separations of the particles by sieving into the five size fractions and subsequent analysis of each fraction. For a two component mixture of particles, however, the above sequence of operations becomes practicable and experimental results are available for such systems (see Sec. B.4, where anomalous ion-exchange kinetics is discussed). Another way to... 

The mechanical sieving of bottom ashes from different periods during combustion shows that when die sand addition decreases, the size of the particles in the bottom ash increases. This is most evident in the fractions around 0.71 nun. When these particles were crushed with a mortar and studied by optical microscopy, it was seen that they consisted of a kernel with a suirounding shell. The kernel was actually mini agglomerates of transparent small particles whilst the shell was more concrete like. The crushed samples were mechanically separated into shells and kernels. A comparative analysis of these was made with an ICP-OES instrument. 

The gas-phase tram-alkylation reaction was performed in an automated micro-flow apparatus containing a quartz fixed-bed reactor (i d. 10 mm) at lO Pa [16 vol% benzene (1, p.a., dried on molsieve), 3.2 vol% diethylbenzene (2, consisting of 25% ortho, 73% meta, 2% para isomers, dried on molsieve), N2 balance (50 mL/min), WHSV =1.5 h ] with 2.0 mL of the tube reactor filled with catalyst particles (500-850 pm sieve fraction, typically 1.4 g). Two separate saturators were connected to the inlet of the reactor for the supply of 1 and 2. The partial vapor pressure of 1 and 2 was controlled by adjusting the temperature of the saturator-condensers and the N2 flow rate. After equilibration for 30 min at the applied reaction temperatures (473 K and 673 K, heating rate 10 K/min) within a dry N2 flow (50 mL/min), benzene (1) and diethylbenzene (2) were passed throu the reactor. To prevent condensation of both reactants and products prior to GC analysis [Hewlet Packard 5710 A, column CP-sil 5CB capillary liquid-phase siloxane polymer (100% methyl) 25 m x 0.25 mm, 323 K, carrier gas N2, FID, sample-loop volume 1.01 pL], tubes were heat-traced (398 K). FID sensitivity factors and retention times were determined using ethene (99.5 %, dried over molsieve) and standard solutions of 1, 2, and ethylbenzene (3, 99%) in methanol (p.a.). The conversion of 2 was measured as a function of time [8]. 

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