GB1231896A - - Google Patents

Abstract

1,231,896. Automatic control of grinding. POLYSIUS A. G. Dec.3, 1968 [Feb.28, 1968 (2)] No.58986/68. Heading G3R. In a grinding mill in which part of the ground material is extracted and part fed back by a mechanical conveyer to be re-ground signals corresponding to the degree of fullness of the mill and the rate at which material is re-fed are compared with one another, any difference controlling the feed of fresh material to the mill. As shown, material to be ground is supplied from a hopper 1 by a conveyer 2 through an air seal 3 to a grinding mill 4. Ground material is extracted pneumatically through separators 5 and 6. Grit from the mill at 10 is fed back to the mill by a bucket conveyer 9 preferably after extraction of any pieces of iron. A signal 12 corresponding to the differential pressure across the mill, and hence the degree of fullness of the mill is compared at 11 with a signal 13 dependent on the power consumption of bucket conveyer 9 so that any difference is automatically eliminated by control of the rate of feed by conveyer 2. Other methods of measuring fullness of the mill and amount of re-fed material are referred to.