Patent ID: 8584978

Claim:
A grinding machine comprising: a grinding head defining an opening; a rotatable advancement member contained within the grinding head; an orifice plate located within the opening of the grinding head, wherein the orifice plate defines an upstream surface and a downstream surface, and includes a plurality of outer grinding openings extending between the upstream surface and the downstream surface for discharging soft material through the orifice plate upon rotation of the rotatable advancement member, and one or more collection passages extending between the upstream surface and the downstream surface for discharging a mixture of soft material and hard material through the orifice plate upon rotation of the rotatable advancement member; a separator assembly located downstream of the orifice plate, wherein the separator assembly includes an upstream inlet that receives the mixture of soft material and hard material from the one or more collection passages; a separator chamber having a wall that defines an axially extending tapered separator passage, wherein the separator passage receives the mixture of soft material and hard material from the upstream inlet, and wherein the wall of the separator chamber includes a plurality of perforations that communicate between the separator passage and an outer surface defined by the wall; and a separator screw disposed within the separator passage of the separator chamber, wherein the separator screw is interconnected with the rotatable advancement member and is rotatable within the separator passage in response to rotation of the rotatable advancement member, wherein rotation of the separator screw causes separation of soft material from the mixture of soft material and hard material and forces the soft material through the perforations in the wall of the separator chamber, wherein the separator chamber defines a downstream end that includes an outlet for discharging hard material; and an open support extending outwardly from the grinding head, wherein the separator chamber is engaged with and supported by the support at a location downstream of the orifice plate.