GB965648A - Grinding plant - Google Patents

Abstract

965,648. Grinding. F. L SMIDTH & CO. A.S. July 24, 1963, No. 29358/63. Heading B2A. A plant for grinding quarried material, e.g. for making cement, comprises an air-swept crusher 2 immediately above and in series with an air-swept tube-mill 11, with gravity feed from the crusher to the mill, the crusher and mill being connected in parallel to receive separate air currents, and an air separator 17 to separate the material into two fractions of different size, pipes leading to the separator from outlets of the crusher and mill, and a pipe 31 to return the coarse fraction from the separator to the mill. As described, material to be ground is fed via a pipe 1 into the hammer-or-impact crusher 2, which is swept by hot air from pipes 3, 4, 5. Crushed material falls through an outlet 8 having a weightcontrolled flap-valve 9 into an inlet 10 at one end of the motor-driven mill 11, which is swept by air from pipes 15, 5. Air leaves the mill through an outlet 12 and a pipe 16 leading to a separator 17, which includes an outlet 18 for a separated coarse fraction and an outlet 19 for a fine fraction. The fine fraction is applied by a pipe 20 to a cyclone 21, which has a bottom outlet 22, separated air being withdrawn by a fan 25 through a pipe 24a, so that the air may be returned in a closed circuit through pipes 24b and 24c to the separator 17, or through a pipe 24d to an air-heating kiln (not shown). Coarse material leaves the mill 11 by an outlet 26 and passes via a conveyer 27 and pipe 28 to an elevator 29 and a wormconveyer 30 which feeds it into the separator 17. The coarse fraction leaving the separator 17 flows through a pipe 31 to the inlet 10 of the tube mill 11. The tube mill may be modified to permit all the ground material to be carried away by air flowing in the mill, in which case material is introduced tangentially at the top of the separator.