Roll crusher and crushing method in use for the roll crusher

A crushing method for use in a roll crusher having a pair of rolls facing each other in which neither roll is spring loaded, comprising continuously feeding feed material to be crushed into a crushing chamber formed in between said pair of rolls, rolling said feed material by rotating said pair of rolls in opposite directions to each other to compress and crush said feed material,

• setting a crushing clearance of said rolls to 0.6 to 2.4 times 80% passing size and maintaining said clearance constant, and
• limiting a feed rate of the material so that a passing rate of the material ranges from 0.5 to 0.8 times the theoretical throughput capacity of the crusher.

A method of operating a roll crusher having a pair of rolls facing each other to form a nip, comprising feeding a material to be crushed to the nip for crushing in the nip, by means of a motor continuously rotationally driving one of the rolls during the feeding and crushing in a direction feeding the material to be crushed into the nip while the other roll is permitted to remain stationary and then by driving means rotationally driving said other roll at a lesser speed than said one roll until the nip is sufficiently fed with the material to be crushed for crushing of said material to begin and for the material being crushed to transmit said continuous rotation of said one roll to effect counter-rotation of said other roll at the same speed as said one roll;

• and, during the effecting of said counter-rotation by the material being crushed, stopping rotationally driving said other roll by said driving means.