Abstract: A discharge grate assembly in a discharge end wall system in a mill shell of a grinding mill. The mill shell defines a mill shell chamber in which a charge including grinding balls and ore-bearing rocks is positioned. The mill shell is rotatable about a central axis thereof for comminution of the ore-bearing rocks to form the grinding balls into worn grinding balls and to produce a slurry including liquid and worn rock pieces from the ore-bearing rocks. The discharge grate assembly includes a body with elongate apertures therein, each aperture extending between a first end thereof and a wider second end thereof. The first and second ends of the aperture are partially defined by respective first and second end walls that are at least partially rectilinear, for impeding the worn grinding balls and the worn rock pieces from lodging in the aperture.

Abstract: A discharge grate assembly in a discharge end wall system in a mill shell of a grinding mill. The mill shell defines a mill shell chamber in which a charge including grinding balls and ore-bearing rocks is positioned. The mill shell is rotatable about a central axis thereof for comminution of the ore-bearing rocks to form the grinding balls into worn grinding balls and to produce a slurry including liquid and worn rock pieces from the ore-bearing rocks. The discharge grate assembly includes a body with elongate apertures therein, each aperture extending between a first end thereof and a wider second end thereof. The first and second ends of the aperture are partially defined by respective first and second end walls that are at least partially rectilinear, for impeding the worn grinding balls and the worn rock pieces from lodging in the aperture.

Abstract: A process for the separation and recovery of bitumen from dry tar sands or sands with negligible quantities of connate water. The process includes comminuting the tar sands to an average particle size of approximately one centimeter in diameter and digesting the comminuted tar sand in a hot, aqueous solution having a pH within the range of pH 10 to pH 14. Optimal digestion is obtained by assuring that the tar sand in the digester is within the range of 50 to 80% solids so as to provide the necessary high shear environment. The digested tar sand is thereafter subjected to a flotation process wherein additional water is introduced to lower the temperature and the solids concentration. Preferably, the pH of the separation cell is maintained above about pH 10. Air is bubbled into the mixture to carry the separated bitumen particles to the top of the separation cell for subsequent recovery.