Can we use the slag of the steel plant as an additive during the cement grinding process, if so, in which percentage? The chemical composition of the slag is: SiO₂ - 14.97 per cent, Fe₂O₃ - 26.89 per cent, Al₂O₃-8.43 per cent, CaO - 21.55 per cent, MgO - 8.48 per cent, Na₂O - 0.249 per cent, K₂O - 0.301 per cent, MnO - 0.15 per cent, Cr₂O₃ - 0.38 per cent, P₂O₅ -0.096 per cent, LOI - 13.22 per cent.

Steel slag cannot be used in the cement grinding process. The slag which can be used is granulated blast furnace slag as it undergoes the pozzolanic reaction and therefore possesses hydraulic properties.

I am making studies for cement plant and would like to make a following question? Is possible to control the weight in the ball mill (cement or raw mill plus balls) in order to save energy? My view point is if you have any chamber unbalanced in ball mill, the motor drive can be working in a forced way and spent much more energy than the necessary? Is possible to use the balls to correct that balance, because today we have in the cement plant a different weight in each chamber?

The weight of grinding balls in the mill and the power drawn by the mill main motor are directly proportional to one another. Therefore it is possible to reduce the power drawn by the mill by reducing the ball charge. However, this will then result in the output of the mill falling due to less grinding balls being present to grind the clinker and generate surface area. As with all these things there is an optimum ball charge and output which corresponds to the lowest unit energy consumption.