Coarse screening

Coarse screens Coarse screens Coarse screens Coarse screens Coarse screens... 

The use of sacrificial anodes in circulating water systems is limited to the application of cathodic protection to stop gates, coarse screens and other plant that are readily accessible so that the anodes can be replaced when they are consumed. Such anodes are not normally used in condensers, pumps and auxiliary coolers for the following reasons ... 

Our data show that the front-to-back ratio (F/B) for a counts after sampling unattached 218Po through a screen is about 2.5 for coarse screens (40 to 80 mesh), increasing gradually to 7 to 11 for finer screens for small sizes. For larger sizes the ratio is closer to 2.5. 

In its simplest form, the ball mill consists of a rotating hollow cylinder, partially filled with balls, with its axis either horizontal or at a small angle to the horizontal. The material to be ground may be fed in through a hollow trunnion at one end and the product leaves through a similar trunnion at the other end. The outlet is normally covered with a coarse screen to prevent the escape of the balls. Figure 2.27 shows a section of an example of the Hardinge ball mill which is also discussed later in this chapter. 

Data validation is very labour-intensive and expensive and is, at best, a coarse screen. A positive solution to the problem is on-line data capture, in which case both the data preparation stage and the need to recheck calculations are obviated. However, interaction by the analyst is stiU advised so that the data are vahdated prior to acceptance. 

This is a unit operation for removal of large solid matter by passing through screens. The efficiency for large solid removal is 50-99% depending on the type of coarse screen or bar screen to be used. 

Thus, pure Mg powd (d 0.60) 225.33g and pure S powd (d>v0.54) 174.67g are mixed thoroughly with 190cc aq Na silicate (d 1.37) and the resulting slurry coarse-screened, air-dried for several hrs and then at 80°. Finally the product was screened to obtain particles of 250—707jr]... 

For coarse screening, the required area per unit of hourly rate may be taken off Figure 12.3. More elaborate calculation procedures that take into account smaller sizes and design features of the equipment appear in the following references ... 

A typical design of an automatic self-cleaning filter allows pressurized dirty water to first enter an upper chamber via a flanged entry port, where the water is filtered through a coarse screen. From here the water is then directed through a stainless steel fine mesh screen located in a lower chamber and out through a flanged exit port. 

Hatch extended his method of analysis to size-distribution curves ranging from coarse-screen analysis through fine particles measured microscopically. While excellent results were obtained by using this technique on laboratory samples, the method cannot be generalized to cover all types of distributions encountered in practice. As already explained in Chapter 3, size-frequency distributions may assume a variety of shapes. The Hatch development applies only to distributions which follow the normal or log-probability law. When size-distributions are hyperbolic in the lower extremes and follow normal log-probability laws in the upper extremes, the Hatch analysis must necessarily fail. Nevertheless, the relationships developed by Hatch have a far-reaching practical importance... 

T) A coarse screen made of metal bars filters large particles and trash such as bottles and cans. 

Related Calculations. Where mechanically cleaned coarse screens are used, the cleaning mechanism typically is actuated by the buildup of headloss. Headloss is determined by measuring the water level before and after the screen. In some cases, the screen is cleaned at predetermined time intervals, as well as at a maximum head differential. 

In recent years the publication of many theoretical structures provides a coarse screen against which one can compare readily available diffraction patterns or unit cell values. The recent syntheses of two such structures - TAMU-1(5) and VPI-5(6) - are witness to the utility of these theoretical tabulations, not only for the conventional alumino-silicate zeolites, but also the increasing number of substituted zeolites and phosphates. However, the ECR-1 structure proposal (7) was not in any of the presently known structure tabulations. ... 

Part was subjected to screening with a metal screen of about 125 ym apertures, mounted on an axial filter. Most of tha biomass was removed in this step, with no significant loss of viscosity. Fluxes in the coarse screening were several hundred gallons per square foot per day. 

Perforated screen plates are useful for coarse separations. Moreover, they resist wear, are less susceptible to blinding, have a high degree of accuracy in sizing, and have a long life. Profile wire, rods, or bars are used for coarse screening and dewatering applications. 

---