Classifiers operating range

Wet classifiers mostly are used to make two product size ranges, oversize and undersize, with a break commonly In the range between 28 and 200 mesh. A rake classifier operates at about 9 strokes/mln when making... 

Aerosol Instrument Classification. Friedlander (34) classified the range of aerosol instrumentation in terms of resolution of particle size, time, and chemical composition. This classification scheme is illustrated in Figure 3. The ideal instrument would be a single-particle counter-sizer-analyzer. Operating perfectly, this mythical instrument would fully characterize the aerosol, with no lumping of size or composition classes, and would make such measurements sufficiently rapidly to follow any transients occurring in the aerosol system. 

Analysis of various tj s of industrial classifiers has led to the observation that the sharpness index is essentially constemt for a classifier (with a fixed geometrical configuration) over its normal operating range. Assuming that bypass is minimal, only two things affect the size distribution of the fine stream the size distribution of the feed and the cut size. Hence, if the size distribution of the feed is constant, only the cut size (c 5o) will affect the size distribution of the fines. Bypass can be minimized by proper design and operation of the classifier. 

Processes operating ia the range of 1300—1530°C produce molten iron, called hot metal or pig iron. These processes are classified as direct smelting processes. Processes operating above 1530°C produce molten steel (qv) and are called direct steehnakiag processes. 

Depending on the means of conversion of manganate(V) to (VI), the process may be classified as a roasting or Hquid-phase process (Fig. 8). The roasting process employs a soHd reaction mixture having a molar ratio between MnO and KOH in the range of 1 2 to 1 3. In contrast, the Hquid-phase route operates at a higher (>1 5) molar ratio between MnO and KOH. 

Centrifuges. Sohd-bowl centrifuges have been proposed as an alternative classifying device to hydrocyclones for cut sizes below 10 pm. The results appear to be mixed (21). In one apphcation, where the cut size was 6.5 pm and the sharpness index 0.7, there was essentially no apparent bypass. However, in other apphcations operating at higher feed concentrations, the cut size ranged from 5—8 pm, but the sharpness index was between 0.3—0.5 and the apparent bypass between 10—30% or higher (22). Smaller cut sizes have also been reported (23). 

For systems following invariant growth the crystal population density in each size range decays exponentially with the inverse of the product of growth rate and residence time. For a continuous distribution, the population densities of the classified fines and the product crystals must be the same at size Accordingly, the population density for a crystallizer operating with classified-fines removal is given by... 

Most forms of dust-collection equipment use more than one of the collection mechanisms, and in some instances the controlhng mechanism may change when the collec tor is operated over a wide range of conditions. Consequently, collectors are most conveniently classified by type rather than according to the underlying mechanisms that may be operating. 

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