GB739578A - Improvements relating to ball or like grinding mills - Google Patents

Abstract

739,578. Ball mills. SMIDTH & CO. AKTIESELSKAB, F. L. June 30, 1954, No. 19225/54. Class 59. A ball or like grinding mill having an inlet at one end for the material to be ground and an outlet at the other end for ground material is provided with a lining which over part only of the axial length of the mill or a grinding chamber thereof tends to classify the grinding bodies by bringing about movement of the smaller grinding bodies in one direction and of the larger grinding bodies in the opposite direction. In the mill shown in Fig. 3 in which a grate 5 is provided to retain the grinding bodies, accumulation of the smallest grinding bodies at the grate is prevented by providing a lining part 6 which has no classifying action. In a modification, Fig. 5 (not shown), parts of the lining next to the grate exert a classifying action opposite to that of the remainder. In the mill shown in Fig. 7 which comprises two chambers 8, 9 separated by a grate 10, the major portion of the lining in the chamber 8 is provided with helical projections which classify the grinding bodies according to size but the lining part 11 is provided with projections parallel to the mill axis which have no classifying action. The chamber 9 is provided with helical projections, those at the outlet end being of opposite hand to those at the inlet end. In a modification, Fig. 8 (not shown), an air-swept mill is provided with frusto-conical rings at the inlet and outlet ends which are separated by a central plain cylinder lining part. In another modification, the classifying lining is omitted over the part of the mill or grinding chamber nearest the inlet.