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Ball mill critical speed

The criterion bv which the baU action in mills of various sizes may be compared is the concept of critical speed. It is the theoretical speed at which the centrifugal force on a ball in contacl with the mill shell at the height of its path equals the force on it due to gravity ... [Pg.1850]

Speed of mill affects capacity, also liner and ball wear, in direct proportion up to 65-75 percent of critical speed. [Pg.1852]

These difficulties are obviated to some extent by arranging the screens in the form of concentric cylinders, with the coarsest in the centre. The disadvantage of all screens of this type is that only a small fraction of the screening area is in use at any one time. The speed of rotation of the trommel should not be so high that the material is carried completely round in contact with the screening surface. The lowest speed at which this occurs is known as the critical speed and is analogous to the critical speed of the ball mill, discussed in Chapter 2. Speeds of between one-third and a half of the critical speed are usually recommended. In a modified form of the trommel, the screen surfaces are in the form of truncated cones. Such screens are mounted with their axes horizontal and the material always flows away from the apex of the cone. [Pg.58]

In this equation, r is the radius of the mill less that of the particle. It is found that the optimum speed is between one-half and three-quarters of the critical speed. Figure 2.28 illustrates conditions in a ball mill operating at the correct rate. [Pg.129]

A serious limitation of the ball or tube mill is that it operates effectively only below its critical speed, as given by equation 2.10. In the planetary mill, described by Bradley et alS2y>, this constraint is obviated by rotating the mill simultaneously about its own axis and about an axis of gyration, as shown in Figure 2.32. In practice, several cylinders are incorporated in the machine, all rotating about the same axis of gyration. [Pg.133]

Nc PARTICLE SIZE REDUCTION AND ENLARGEMENT Critical speed of rotation of ball mill (rev/time) Units in SI System s-1 145 Dimensions in M, L, T T-l... [Pg.145]

Data Are for a Cylindrical Mill 19 X 36 In., Batch Circuit 50 Percent Critical Speed Ball Load 28 Percent 21/i In., 40 Percent 2 In., 18 Percent V/% In., 7 Percent l1/ In., 7 Percent 1 In. Consistency 60 Percent Solids Load 796 Lb Volume 45 Percent... [Pg.463]

A ball mill with an inside diameter of 12 ft (3.66 m) is charged with 129 tons (117,000 kg) of balls that have a maximum diameter of 3 in (0.076 m) and occupy 46.3 percent of the mill volume. The mill is operated wet at 62.4 percent of critical speed. What is the horsepower needed to drive the mill... [Pg.476]

The critical speed of a ball mill is the speed at which the balls just begin to centrifuge with the mill. Thus, at the critical speed, the centrifugal force is equal to the weight of the ball. At and above the critical speed, no significant size reduction occurs. The critical speed nc is given by the equation... [Pg.1167]

A larger mill reaches its critical speed at a slower revolution rate than a smaller mill. Ball mills are operated at from 60 to 85% of the critical speed. Over this range, the output increases with the speed however, the lower speeds are for finer grinding. An empiric rule for the optimum speed of a ball mill is... [Pg.1167]

Mill rotation speeds are set such that the balls are lifted nearly to the top of the jar before tumbling to the bottom. As a rule, about 50-75% of the critical speed or the speed at which the media are held to the walls by centrifugal force is appropriate. The critical speed (in rpm) can be calculated as TTij r, where r = jar radius (cm). [Pg.32]

Speed of Mills.—This is properly a direct function of the internal radius, and is something less than the critical speed. The critical speed of any mill is that which will make the layer of balls next to the shell cling to the latter as the mill... [Pg.208]

Ball mills are better suited than rod mills to fine grinding. The charge is of equal weights of 1.5, 2 and 3-in. balls for the finest grinding. The volume occupied by the balls is 50% of the mill volume. Rotation is 70-80% of critical speed. Ball mills have a length-to-diameter ratio of 1-1.5. [Pg.450]


See other pages where Ball mill critical speed is mentioned: [Pg.78]    [Pg.513]    [Pg.1850]    [Pg.128]    [Pg.128]    [Pg.145]    [Pg.29]    [Pg.30]    [Pg.342]    [Pg.342]    [Pg.840]    [Pg.483]    [Pg.29]    [Pg.30]    [Pg.455]    [Pg.455]    [Pg.460]    [Pg.461]    [Pg.475]    [Pg.476]    [Pg.476]    [Pg.342]    [Pg.342]    [Pg.847]    [Pg.370]    [Pg.378]    [Pg.832]    [Pg.2348]    [Pg.342]    [Pg.342]    [Pg.833]    [Pg.342]    [Pg.342]    [Pg.777]    [Pg.2306]   
See also in sourсe #XX -- [ Pg.200 ]




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