I have to ask you a question with regards to the chlorides and kiln-preheater operations. The Cl in our limestone is approx 0.003-0.007. However, I have to go down a bench in the quarry and the chlorides down there are like 0.027 based on one of the samples (the high chlorides as a result of the sea bed interface). My quarry is actually being exhausted and I am forced to go down there to buy some time till town and country planning approve new quarry lands. What we have is a VA design with a pair of 1st Stage Cyclone, one 2nd stage cyclone and three shaft stages. They went with this design as it lends itself to the least possibility of plugging. This leads me to the question....How forgiving is a shaft stage preheater?

The calculation of gas and material flow in the preheater relies on the principles of stoichoimetry (to assess the combustion gas products from the fuel) and the conservation of mass. In principle what goes into the kiln must come out somewhere and will allow you to prepare a mass balance for the kiln. With regard to the brown clinker you are producing this is most probably caused by having reducing burning conditions in the burning zone of the kiln. This is very bad for clinker quality and fuel efficiency of the kiln. Almost certainly the problem is with the kiln burner and might be solved by adjustment. You must be sure that you maintain at least one per cent oxygen at the kiln inlet.