Patent ID: 7484680

Claim:
A grinding machine comprising: an orifice plate including hard material collection passages leading to a collection housing, wherein the collection housing includes an upstream collection area that receives hard material from the hard material collection passages; a discharge passage extending in a downstream direction from the collection area; a rotatable flighted auger extending through the collection area and into the discharge passage, wherein the flighted auger defines a downstream end; an open hard material outlet passage located downstream of the discharge passage and downstream of the downstream end of the flighted discharge auger; wherein the discharge passage is defined by an inner surface that includes a helical discharge flute in communication with the open hard material outlet passage; wherein the helical discharge flute and the discharge auger are configured such that the helical discharge flute extends to the downstream end of the discharge auger, and wherein the helical discharge flute cooperates with the discharge auger to advance hard material through the discharge passage and into the open hard material outlet passage upon rotation of the discharge auger.