-

Work index is a measure to define ores/minerals grindability which is significantly used in Bond (1952) to calculate the required energy of ores' comminution. Work index for any material is experimentally calculated under specific conditions and it is a certain value. To understand the effect of changing control screen in work index calculation, three different ores Alam-Kuh Pb-Zn ore, Sarcheshmeh Cu ore, and Abe-Gann region Dolomite were tested, using 425, 212, 150 and 100 micron screens (totally 12 sets of tests). Results showed that the work index values increase with the increases of screen size. The relation between root of screen
size and fines produced per revolution of mill and also, screen size and size of
products out of which 80% passes through this size appeared to be linear for all three different ores. The constants of these linear equations were estimated using regression technique.