We are producing the clinker with a C3S content of 54-58%, Litreweights 1200+/-50 grams, liquid content 28+/-0.5%. The alumina ratio in kiln feed is maintained 1.33 to 1.36 and silica ratio 2.1+/-0.05.
We have two problems :-
Our clinker grindability is showing a bit poor i.e.the cement mill output reduces with this clinker by upto 10%.
The other problem is more fines in the clinker produced. The fines are in the range of around 20 +/- 2 % causing lot of dust recirculation at kiln outlet very often. The visibility in the kiln becomes poor at no. of times forcing the operator to reduce the kiln output.
The kiln is 6 stage double string ilc kiln and we run the bottom stage temperature around 900-920. The DOC is 95-96%. The fifth stage divertor is open 20% and the kiln inlet temperature is more than 1200 most of the time. The kiln filling degree is 14-15%.
Kiln feed residue is 12-14%.
Pls suggest suitable changes in the raw mix or kiln operation to sort out the problems as mentioned above.
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Re: Clinker Grindability
Though i am not an expert;but it seems that your alumina modulus is abnormally very low. It should be more than 1.50 for better clinker nodulisation and to check dusty clinker. Alumina increase viscosity and decrease surface tension; both aspcts beneficial for better nodulisation. Clinker grindability also depends on its size and undersize clinker is hard to grind.
You may also increase residue of kiln feed for the sake of porous clinker to improve upon grindability.