Abstract: A ball mill comprising a horizontal mill casing provided with means of magnetizing-force generation which are identically constructed and equidistantly spaced electromagnets forming a plurality of electromagnet rows, fixed in space, equally spaced apart and extending from one end to the other of the casing within two angular zones fixed in space, first from 135.degree. to 180.degree. and second from 225.degree. to 360.degree., thus presenting a plurality of magnet columns in circular direction, and which is provided with a switching circuit network for keeping the electromagnets of the lowermost row in the second zone in energized state and energizing and de-energizing all other electromagnets alternately and cyclically in two groups, such that every electromagnet of one group is sided, in crisscross directions through row and column, by electromagnets of the other group.