With screening, crushing a double function, can be done individually screening and crushing operations, cancel preferred, simplified process systems to reduce investment in civil construction and equipment of the spiral arrangement of broken teeth, the relative rotation of the two rollers like grizzly, particle size may be smaller than sieve to the material, only the particle size is greater than required for crushing the material to avoid the crushing weight of physical defects doping products in the piece rate, over-grinding is low, broken low energy consumption;