A grate plate for use with a pulp lifter at a discharge end of a grinding mill , the grate plate having an outer edge , an inner edge , a leading side edge and a trailing side edge , wherein the leading side edge and the trailing side edge have complementary shapes so that a series of grate plates can be mounted to the pulp lifter in a circular or annular array, with the leading side edge of each grate plate being adjacent the trailing side edge of an adjacent grate plate in the array, the grate plate comprising openings for passing through ground material particles of a predetermined size or smaller from the interior of the drum towards the pulp lifter, and the grate plate further comprising, on a surface configured to face the interior of the cylindrical drum, one or more sections of lifter bars arranged so that the lifter bar sections on a number of adjacent grate plates complement each other to form lifter bars, wherein the lifter bar sections are shaped so that at least portions of the resulting lifter bars are inclined or curved (α) in a first circumferential direction (R) of the circular or annular array relative to a radial line (r L ) of the array intersecting the respective lifter bar or lifter bar portion, characterized in that at least portions of the complementary leading and trailing side edges of the grate plate are inclined or curved (β) in a second circumferential direction of the array relative to a radial line (r s , r T ) of the array running through the point of intersection of the respective side edge with the outer edge , wherein the second circumferential direction is opposite the first circumferential direction (R). the grate plate having an outer edge , an inner edge , a leading side edge and a trailing side edge , wherein the leading side edge and the trailing side edge have complementary shapes so that a series of grate plates can be mounted to the pulp lifter in a circular or annular array, with the leading side edge of each grate plate being adjacent the trailing side edge of an adjacent grate plate in the array, the grate plate comprising openings for passing through ground material particles of a predetermined size or smaller from the interior of the drum towards the pulp lifter, and the grate plate further comprising, on a surface configured to face the interior of the cylindrical drum, one or more sections of lifter bars arranged so that the lifter bar sections on a number of adjacent grate plates complement each other to form lifter bars, wherein the lifter bar sections are shaped so that at least portions of the resulting lifter bars are inclined or curved (α) in a first circumferential direction (R) of the circular or annular array relative to a radial line (r L ) of the array intersecting the respective lifter bar or lifter bar portion, characterized in that at least portions of the complementary leading and trailing side edges of the grate plate are inclined or curved (β) in a second circumferential direction of the array relative to a radial line (r s , r T ) of the array running through the point of intersection of the respective side edge with the outer edge , wherein the second circumferential direction is opposite the first circumferential direction (R). <EOS>