Economics and methodology of ball mill media maintenance

Abstract

There are literally thousands of ball mills in use throughout the world, many of them in the cement industry. Few installations have a comprehensible method of controlling and recording exactly what ball size distribution is in, or should be in, the ball mill. As mills are supplied for ever increasing capacities, the ball size distribution and wear exact a tremendous effect on the profitability of producing finish cement. Improper size distribution or filling level of the ball charge can easily reduce the efficiency of grinding (possible production rate) by 5% to 20%. Relating an efficiency loss of only 5% for a mill with a capacity of 150 Stph, results in a loss of saleable cement at $90/Ston of $5.0 million per year. Online, real time information from the grinding process has aided in the attempt to reach peak performance, but for many grinding installations, maintenance of the grinding media remains in the dark ages.