Roll Crusher Product Characteristics


	Roll Crusher Product Characteristics

On the soft and medium grades of stone, to which the single-roll crusher is particularly well adapted, the machine will turn out a product carrying less fines than will either the jaw or gyratory types; in fact, the product of the single-roll machine on soft rock will generally compare favorably, on this score, with that of the other two types on hard rock. There is no tendency to build up a packed condition in the lower part of the crushing chamber; rock reaching this lower zone is quickly and forcibly discharged. Moreover, the selective characteristic of the crusher minimizes attritional action by getting the fine material out of the way quickly, and most of the crushing is done by clean, sharp sledging blows against the individual pieces.

The size of product is governed by the distance between the roll and the tip of the concaves at the lower end of the anvil, which corresponds to the open-side discharge setting of the jaw and gyratory types. There will of course be some

difference in the size of product, depending upon whether the concaves are smooth or corrugated at the discharge point. With smooth concaves, and operating on soft or medium stone, the product will average from 80 to 85 percent passing a square opening equivalent to the discharge setting. With corrugated concaves the product will be somewhat coarser. If the rook is hard the lower end of the anvil will be forced away from the roll a little when the crusher is fully loaded, due to compression of the springs, and this may increase the square-opening size of product by as much as 1 in.

The single-roll crusher is essentially a primary crusher, and general results will be better if the instal1ation is engineered with that thought in mind. The machine will function more satisfactorily and economically when fitted with corrugated concaves, and set for a medium or coarse product, than when fitted with concaves which are smooth at the discharge point, and set "tip-to-tip."

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