Spiral classifiers

Bird number (mass of solids with a 0.1 density variation from the cut density) 15 particle cut diameter 50 pm but usually 1000 to 20000 pm. 

Separation efficiency is 50 % that is, use double the cross section area obtained from the settling velocity of the limiting particle diameter. 

Underflow solids capacity is a function of the spiral diameter and solids density independent of the separation. Angle of inclination 16°. 

High weir 1 rrf pool area produces about 5 kg/s dry solids in the overflow with 400 pm limiting diameter or about 280 pm cut diameter and 30 % concentration. Submerged weir 1 m pool area produces about 0.5 kg/s dry solids in the overflow with 150 pm limiting diameter or about 100 pm cut diameter and 16% concentration. 

For both configurations, increasing the area by a factor of 10 increases the amount of overflow solids by 10 with the same cut and limiting diameters and overflow concentrations. 

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Essentially a spiral classifier with paddles replacing the spiral. 

One form based on scrubber, another on spiral classifier. They have wash water added to flow essentially horizontally in opposite direction to underflow which is conveyed and resuspended by some form of spiral. 

In friability tests the material s susceptibility to attrition is evaluated. But it is not as simple as it may seem at first to select the suitable test procedure. In this context Pell (1990) gave a simple thought experiment to illustrate the difficulties If we took a batch of rubber stoppers and a batch of diamonds, and rubbed them on abrasive paper, we would conclude that the diamonds were more attrition resistant. If we instead struck the particles with a hammer we would conclude that the rubber were more attrition resistant. So, different test methods can rank materials differently with respect to their attritability. This effect was for example observed by Knight and Bridgwater (1985). They subjected spray-dried powders to a compression test, a shear test and a test in a spiral classifier. They found that each test gave a different ranking of the materials. Obviously, there is no... 

Alpine Mikroplex Spiral classifier, 22 289 Al-Sol catalysts, 11 690 -al suffix, 2 58... 

For vibrating screens, the suitable parameter X is the screen deck area multiplied by the length in m3. Cost includes drive- and feed-boxes, and excludes motor, starter, and screen cloth. For spiral classifiers, the suitable parameter X for costing is the spiral diameter, in cm. Cost includes the motor. For hydrocydones, the suitable parameter X for costing is the cyclone diameter, D, in cm. Cost includes fittings and combination urethane—ceramic liners. The appropriate values of X and the coefficients are given in Table 4. 

Rake and Spiral Classifiers Rake-type classifiers such as the Dorrf classifier and spiral types such as the Akinsj have been the workhorses for general-classification problems for half a century, and their names describe the mechanisms installed in sloping-bottom tanks. See Fig. 19-24. Mechanically the devices are powerfully built, and functionally they are versatile and flexible. They were tfie first classifiers used successfully for closed-circuit grinding. Separations as fine as 325 mesh can be accomplished at reduced tonnage rates. 

Prior to digestion, the ore must be finely ground. The chromium ore concentrate enriched by gravitational processes (e.g. spiral classifiers, settling machines etc.) is supplied with a particle size of ca. 0.5 mm. Ball-milling coupled with air classifiers yields a particle size of <0.1 mm. The sodium carbonate is also ground. Since the sodium chromate formed melts at 792°C, the addition of an inert diluent, which can absorb sodium chromate like a sponge, is necessary to enable air to come into contact with the reaction mixture. 

Separate solids with similar densities based on cut diameter. Conveying fluid is a gas such as air. Contrast with hydrocylcones and spiral classifiers, where the conveying fluid is a liquid such as... 

The attrition slaker uses twin propellers with opposed pitches to slake the lime and break down the weaker particles of grit. The remaining grit may be removed in a spiral classifier and fed to a ball mill. 

To separate solids having about the same density but with a range of partide size, separate based on cut diameter and use air or liquid classifiers such as cyclones, hydrocyclones or spiral classifiers Particle size 25-2000 [xm feed solids concentration 5 to 40%. Cut diameter is the particle diameter that has equal chance to report to either the overflow or the underflow streams. 

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