capacity of the single-roll crusher

The capacity of the single-roll crusher is influenced by the nature of the feed to a much greater extent than is the case with any of the types discussed heretofore. The two factors which have a very important bearing on capacity are thickness and hardness, or toughness. Blocky material which must be broken on top of the roll will, unless the stone is very friable, require a considerable amount of hammering by the slugger teeth to reduce the block s to sizes that can be gripped between the teeth and the anvil-all of which is a time consuming process. The harder the material is, the more time will be consumed in such impact breaking.

Hardness or toughness al so has a retarding effect upon the sledging action on the smaller pieces of material; instead of shattering, as soft rock will under these sledging blows, the harder material snaps off in small pieces at the point of impact, which means that more blows are required to reduce each individual block again a time consuming operation. Because the action of the crusher is of this nature, it is not practicable to give the various crusher sizes a unit capacity rating to correspond to each discharge setting, or product size, as can be done with reasonable accuracy for the gyratory and jaw types. It is necessary to predicate the ratings upon selected values of hardness and maximum thickness of the, feed, as well as the discharge setting.

In Table I this has been done for four sizes of the Fairmount crusher. The material upon which this table is based is a medium limestone, of 8000 to 10,000 p s i crushing strength. On this basis ratings are given for different thicknesses of feed, and for different product sizes.