Abstract: For use in a basket mill having a process vessel in which particles are ground so as to reduce their size, a basket for retaining a grinding medium, having an opening in its top and a screen at its bottom. A first shaft extends into the basket and has a grinding assembly extending from the shaft. A first drive apparatus rotates the first shaft at a first rotational rate. A second shaft is coaxial with the first shaft and has an impeller for causing material to be ground to move into the basket through the opening and out of said basket through the screen. A second drive apparatus rotates the second shaft at a second rotational rate independent of the first rotational rate. The first shaft may be a tube. A tube may be disposed within the first shaft, and have at its end a bushing for receiving for rotation the second shaft. The bushing may be located outside of a region of the basket where grinding media is disposed. Methods for operating the apparatus.

Abstract: For use in a basket mill having a process vessel in which particles are ground so as to reduce their size, a basket for retaining a grinding medium, having an opening in its top and a screen at its bottom. A first shaft extends into the basket and has a grinding assembly extending from the shaft. A first drive apparatus rotates the first shaft at a first rotational rate. A second shaft is coaxial with the first shaft and has an impeller for causing material to be ground to move into the basket through the opening and out of said basket through the screen. A second drive apparatus rotates the second shaft at a second rotational rate independent of the first rotational rate. The first shaft may be a tube. A tube may be disposed within the first shaft, and have at its end a bushing for receiving for rotation the second shaft. The bushing may be located outside of a region of the basket where grinding media is disposed. Methods for operating the apparatus.

Abstract: A colloid mill includes a rotor turning relative to a fixed stator with a narrow passageway therebetween through which a slurry is passed to produce a fine colloid. A cooling fluid is passed through a hollow annular passageway within the stator to cool the stator and the slurry adjacent thereto. A cooling fluid is also passed through an input tube in the center of the rotor shaft, then through a hollow annular passageway within the rotor, to cool the rotor and the slurry adjacent thereto. The rotor cooling fluid exits the rotor through an annular exit passageway between the rotor shaft and the input tube.