Patent ID: 8047459
Filing Date: 2011-11-01
Classification: B02C

Abstract:
1. For use in a basket mill having a process vessel in which particles are ground so as to reduce their size, an apparatus comprising: a basket having an opening in its top and a screen at its bottom, said basket being for retaining a grinding medium; a first shaft extending into the basket and having a grinding assembly extending from the shaft; a first drive apparatus for rotating said first shaft at a first rotational rate; a second shaft coaxial with the first shaft, said second shaft having an impeller for causing material to be ground to move into said basket through said opening and out of said basket through said screen; wherein the first shaft is a first tube, and wherein a second tube is disposed within said first shaft, said second tube having at a first end of said second tube a bushing for receiving for rotation said second shaft, said bushing being located outside of a region of said basket where grinding media is disposed, so as not to be exposed to said grinding media; and a second drive apparatus for rotating said second shaft at a second rotational rate independent of said first rotational rate.