We've been faced with a problem that the collecting efficiency of the electrostatic precipitators lowers remarkably since having started to use sewage sludge as the secondary material. I'm not sure where the cause is from. Is there any possibility of causing such problem by using sewage sludge, and which kind of components that sewage contains can affect the performance of ESP? As the reference, we've been experienced in the same problem when we used TPA sludge(Telephtalic Acid) two years ago.

I have not heard of this phenomenon before. The resistivity of the dust exiting the preheater must be changed when burning these sludges. I hope all the sewage sludge is being burnt in the kiln and the problem is not caused by organic residues entering the ESP. If so then the problem can only be associated with volatiles derived from the sludge entering the ESP with the dust. The most likely source is chlorides from the sludge. You should also check carefully that the problem is not caused by mercury from the sludge. If so then you have a big problem.

Many cement plants add high ballast and high ash fuels through the firing system. However, I do not know of any plant that is specifically doing that with iron additive. I also see no reason to do that. There are potential problems of in homogeneity in the clinker. Also you need the iron to form flux in the transition zone, not at the end of the burning zone.

What kind of changes are required in raw mix to increase the granulation with 50 per cent pet coke total CV 4.3 per cent, LSF 93, SM-2.1 per cent, AM-1.0 per cent, in kiln feed?