Abstract: A method for operating a crushing and grinding facility is disclosed in which crushing of mine-run material is controlled to always match grinding feed requirements while both crusher(s) (10) and grinding mills (16) operate full time and draw full power during the hours of what may be unequal length working days. The grinding mill (16) is also operated to produce the maximum output of final product that is within its existing capabilities. At each of a succession of measurement times (e.g., every 1/2 hour during a 22-hour working day of the mill), the rate of production of final product by the grinding mill (6) is ascertained (as by 21, 22, 23) and projected to the end of the mill working day.

Abstract: For control of a crushing plant to ensure both that a quota quantity of product is produced during each working period and that the product has optimum economic value by reason of small particle size, determination is made of the amount of product passed through the plant from the beginning of the period to each of a number of measurement times during the period. Each such determination gives a "still to go" quantity, hence a theoretical new feed rate to be maintained. The rate of feed of material into the plant is adjusted in correspondence with the ratio between that theoretical rate and the actual feed rate prevailing during an interval just before the measurement time.