Do you think that pre-dedusting in a raw mill circuit by means of cyclone with a separation efficiency of 91-93 will have negative influence on the raw mill bag filter or ESP in regard to the fact that after pre-dedusting only rather fine grain and rather low quantity of dust will enter the filter? Could it become difficult to clean the bags due to fine dust getting deeper into the pores of the filter bag and could the fine dust have negative influence on the ESP?

I cannot foresee that reduces the load of dust entering a filter will have any detrimental effect on its performance. Certainly no problem with an ESP. Your point regarding fine dust blinding the cloth of fabric filters maybe valid, but I would be surprised.

What is the best method to charge a ball mill ?

The normal method to charge balls into the ball mill is to position the doors at the top of the mill and remove them. Then to pour the barrels of grinding balls into the mill using an overhead crane. The exact grading of media required is identified by performing an axial test taking samples along the axis of mill. You want the desired fineness to be reached at the exit of the mill and adjust the ball grading to achieve this. For a new mill you need to rely on the experience of the commissioning engineer to determine the initial ball grading. It is normal practice to begin commissioning with only 65 per cent of the balls in the mill and bring this up to target by additions with monitoring between additions by axial testing.