Blake crushers

Jaw crushers are used as primary crushers and are often followed by other types of crushers. Blake crushers come in various sizes from about 10 to 400 HP. Smaller jaw crushers are manufactured with capacities of 1 to 10 HP. 

A material is crushed in a Blake jaw crusher such that the average size of particle is reduced from 50 mm to 10 mm, with the consumption of energy of 13.0 kW/(kg/s). What will be the consumption of energy needed to crush the same material of average size 75 mm to average size of 25 mm ... 

Figure 12.5. Jaw, roll, impact, and tumbling equipment for size reduction, (a) Blake-type jaw crusher operates at 200-300 strokes/min (Allis-Chalmers Co.), (b) Smooth roll crusher, for which operating data are in Table 12.8(b). (c) Swing hammer mill operating data in Table 12.7(a). (d) View of a conical ball mill, showing distributions of balls and material and crusting ranges data in Table 12.6(b) (Hardinge Co.). (e) Tube mill with three compartments, length to diameter ratio 3-5. (f) Rod mill in a cylindrical tumbler, LID = 1.2-1.6 data in Table 12.6(d).

Fig. 2 The essential features of (A) Dodge, (B) Blake, and (C) single-toggle jaw crushers.

Fig. 3 Cross section of a Blake-type jaw crusher showing the nonchoking design of the swing jaw.

The most common type of jaw crusher is the Blake crusher, illustrated in Fig. 29.2. In this machine an eccentric drives a pitman connected to two toggle plates, one of which is pinned to the frame and the other to the swinging jaw. The pivot point is at the top of the movable jaw or above the top of the jaws on the centerline of the jaw opening. Thp greatest amount of motion is at the bottom of the V, which means that there is little tendency for a crusher of this kind to choke. Some machines with a 1.8- by 2.4-m (72- by 96-in.) feed opening can accept rocks 1.8 m (6 ft) in diameter and crush 1200 ton/h to a maximum product size of 250 mm (10 in.). Smaller secondary crushers reduce the particle size of precrushed feed to 6 to 50 mm ( to 2 in.) at much lower rates of throughput. 

The Blake crusher in Fig. 14.5-2b is more commonly used, and the pivot point is at the top of the movable jaw. The reduction ratios average about 8 1 in the Blake crusher. Jaw crushers are used mainly for primary crushing of hard materials and are usually followed by other types of crushers. 

Figure 14.5-2. Types of jaw crushers (a) Dodge type, (b) Blake type.

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