A mathematical model was developed for the grinding and flotation section of Union Carbide’s Bishop mill and this model was used to indicate how variations in grind, retention time, and calcite and fluorite content effects the mill capacity, tungsten units produced, and the grade and recovery of the scheelite concentrate. A model such as this is a starting point in determining the economic optimum running condition for a mining and milling operation and an example of this is given.
Procedure & Data
Samples were taken of the sulfide rougher tails, the feed to the scheelite float section, seheelite cleaner tails and each of the tails and concentrates of the 10 scheelite rougher cells in that section. Time-weight samples were taken of each concentrate and the cleaner tails so that mass flows could be calculated. Each concentrate sample was weighed wet, screened wet on a 200-mesh screen, filtered and dried. The dried sample was weighed and pulp densities and mass flows calculated. Figure 1 shows the flotation circuit and the sampling points.
During the sampling period,the flotation procedure was not changed; therefore no information was obtained on many of the flotation variables. The results can be used, however, to indicate how retention time, feed