OPTIMIZATION OF COMMINUTION CIRCUIT THROUGHPUT AND PRODUCT SIZE DISTRIBUTION BY SIMULATION AND CONTROL

The goal of this project is to improve energy efficiency of industrial crushing and grinding operations (comminution). Mathematical models of the comminution process are being used to study methods for optimizing he product size distribution, so that the amount of excessively fine material produced can be minimized. This will save energy by reducing the amount of material that is ground below the target size, and will also reduce the quantity of materials wasted as ''slimes'' that are too fine to be useful. This will be accomplished by: (1) modeling alternative circuit arrangements to determine methods for minimizing overgrinding, and (2) determining whether new technologies, such as high-pressure roll crushing, can be used to alter particle breakage behavior to minimize fines production. In previous quarters, it was determined that the primary grinding mills were operating at less than full capacity, suggesting that a shift of grinding load to the primary mills could liberate more material before it reached the secondary mills, allowing more complete liberation with a coarser grind. In the eighth quarter, further analysis was carried out to determine the full extent of the benefit that could be obtained by this shift in grinding load. A key part of this analysis was the development of a correlation of the circuit capacity with (a) ore work index, (b) the quantity of primary mill ''pebbles'' that were crushed by a cone crusher in the circuit, and (c) the fraction of the crushed pebbles that were also processed by a high-pressure roll mill.