Patent ID: 9675978
Date: 2017-06-13
CPC Classifications: B02C

Claim:
1. An attrition mill that includes an internal structure and grinding media for grinding particles into coarse and fine particles and classifying and separating the fine particles from the coarse particles using a classification and separation stage in which fine particles are separated from coarse particles and removed from the mill along its length and coarse particles are recycled internally in the mill, the attrition mill comprising: a grinding chamber having an elongated cylindrical side wall, an inlet positioned at or near an upstream end of the grinding chamber, an outlet positioned at or near a downstream end of the grinding chamber, an axial shaft located in the grinding chamber and extending in a direction from the upstream end to the downstream end, the axial shaft being rotatably driven, a plurality of spaced grinding elements in the grinding chamber, each of the plurality of spaced grinding elements being concentrically mounted radially and in a perpendicular orientation relative to the axial shaft, each element being spaced from an adjacent element, each element having a front face that is perpendicular to the axial shaft and including one or more apertures or spaces therein to provide a flow path through each element for slurry and grinding media, each aperture having side walls extending from the front face of the element to a rear face of the element, the side walls being generally perpendicular to the front face, the axial shaft being exposed in between each of the elements thereby allowing passage of slurry and grinding media along and through the grinding chamber from the inlet to the outlet in a direction from the inlet to the outlet, and wherein the fine particles are passed to the outlet and wherein the coarse particles are internally recycled back towards an upstream end of the grinding chamber, wherein at least one of the plurality of grinding elements with the apertures therethrough provides a larger flow path therethrough for the slurry and grinding media compared to one or more of the other of the plurality of grinding elements; and wherein the total open area of the apertures of the at least one of the plurality of grinding elements providing the larger flow path is larger than the total open area of the apertures in one or more of the other of the plurality of grinding elements in the mill.