Abstract
The study reports on the grinding test conducted on an oxidised copper-cobalt ore in order to determine the milling parameters using pear-shaped ball mill. Twelve mono sized fractions of an oxidised copper-cobalt ore sample were prepared and wet ground batch wise using a laboratory-scale ball mill at the University of Lubumbashi: -6700 + 4750, -4750 + 3350, -3350 + 2360, -2360 + 2000, -2000 + 1700, -1700 + 1400, -1400 + 1000, -1000 + 850, -850 + 500, -500 + 250, -250 + 125 and -125 + 75 microns. After the sample and the balls were loaded to the ball mill, it was run for seven different time intervals (½, 1, 2, 4, 8, 15 and 30 minutes). The short time (½ minute) provided data more closely related to the Breakage Function (B) since less secondary breakage was hypothesised.
The data collected was used to determine some of the selection (S) and B Function parameters. The remaining parameters were estimated using a population balance model simulator that seeks the best combination of these parameters in order to minimize the residual error between the experimental and predicted product size distributions (PSDs). To evaluate the kinetics model developed, an un-sized oxidised copper-cobalt ore sample was also milled for ½, 1, 2, 4, 8, 15 and 30 minutes. The measured (PSDs) obtained fairly agreed
with the predicted ones. This suggested that the S and B Functions parameters obtained can be used for continuous operation mass balances.