Crushing and Grinding | Classification of Crushing and Grinding Machinery or Equipments

The general terms used to describe the operations that subdivide solids mechanically are seldom used with any very definite significance. The terms crushing and grinding are usually associated in this phrase to signify subdividing to greater or less extent, neither of the terms is used alone with any precise meaning, although, in general, grinding means subdividing to a finer product than crushing.

Crushing & Grinding Equipments

In spite of the wide use of crushing machinery in hard-rock practice in the mining industry, little is really known of the basic theory that underlies processes for the mechanical subdivision of solids. As in certain other fields, this lack of theory and total reliance on empirical observation have led to an especially wide variety of types of equipment. By a process of a natural selection rather than analysis, certain devices have become preeminent for hard-rock crushing, and as a result, the mining industry in recent years has practically standardized on certain types of machines for specific ranges of crushing.

In the fields in which the chemical engineer is interested outside hard-rock practice, there is absolutely no standardization. Consequently we shall be largely a description of types of crushing machinery with an indication of the uses to which such apparatus is suited, although such usage arises more often from tradition and custom than from rational comparisons.

Classification of Crushing and Grinding Machinery:

Because of wide variety of devices used, it is extremely difficult to make a rigid classification of crushing machinery. The only classification in which definite limitations of the groups can be established is the division into coarse crushers, intermediate crushers, and fine grinders. Coarse crushers are defined as those types of machinery that can be developed to take, as feed, lumps as large as may be desired. Fine grinders are defined as those machines that can be made to give a product that will pass a 200-mesh screen. Intermediate crushers are those machines that ordinary do not take indefinitely large feed, nor will they make a product that will pass a 200-mesh screen.

The different devices may be classified under these heads as follows:

1.Coarse Crushers

(a) Jaw Crusher
(i) Blake Jaw Crushers
(ii) Dodge Jaw Crusher
(b) Gyratory Crusher

2.Intermediate Crushers

(a) Rolls
(b) Disc Crushers
(c) Edge Runners
(d) Disintegrators (cage)
(e) Hammer Mill

3.Fine Grinders

(a) Centrifugal
(i) Raymond
(b) Buhrstones
(c) Roller Mills
(d) Ball Mills and Tube Mills
(e) Ultra-fine Grinders

Machines in the coarse crusher class are ordinary employed where the feed is from 1 1/2 to 2 in. in diameter and larger. The largest devices of this class that have been made will take rocks up to 60 in. in diameter. No type of crusher except those listed in this class can be built in sizes that will take these very large pieces of feed.