Hello Sinan,
The main effect would be to slightly increase the calorific value of your fine coal. A reduction of 6% to 3% meal dust in your fine coal would increase the calorific value of the fine coal by only 3%.
For example, if your raw coal had a calorific value of say 28MJ/kg then at 6% meal dust the fine coal would have an energy value of 0.94*28= 26.32 MJ/kg. If the meal dust contamination was reduced to 3%, the energy value of the fine coal would be 0.97*28
= 27.16 MJ/kg. This is only a 0,84MJ/kg improvement and it is probable that your raw coal would vary by more than this from day to day, even possible hour to hour So, I would suggest that you would probably not see much of an improvement in the kiln.
Many plants are happy with 5% carry-over dust in their fine coal. Up to a point, meal dust in the fine coal can increase the luminosity of the flame and therefore improve the amount of heat radiating onto the clinker bed, improving clinkerisation.
Regards,
Ted.