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Technical Cement Forum / High free lime in clinker

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xxxx 27/12/2012 16:05:44

High free lime in clinker

Dear All

I am facing problem of very high free lime in clinker upto 4% , the litre weight is 1100 to 1200 but free lime is still high.

Previously withthis litre weught i was getting 1.5 to 2% free lime , but now my kiln production has reduced from 155 tph to 140 tph kiln feed.

Raw meal residue are same 17% on 90 mic & 2 % on 212 mic. , coal mix is 80% petcoke & 20% south african coal with mix residue of 3-3.5% on 90 mic.

Kiln inlet no CO , oxygen around 2.3% , ILC kiln

Flame momentum 1800%m/s .

SO3 in hot meal 1.3% , while calcination in hot meal is more than 99% .

If i reduce coal in calcinator my freelime increases & clinker litre weight goes down.

Also brown core inside clinker nodules are seen.

Please suggest.

Engr

Belite 07/01/2013 12:03:40

Could be a sulphur cycle inside the rotary kiln. If the kiln is dusty the SO2 may not reach the calciner. CaSO4 decomposes easily, which can give a higher free lime.

Try as an experiment to increase the oxygen at the back end by increased draft. If my guess is correct, it should help once the excess sulphur is out of the system.

GSMS 11/01/2013 08:49:54

Please Check the following:

The silica modulus in the kiln feed for any abnormality
The free silica in Kiln feed for any abnormality
Brown core inside clinker nodules can be related to reducing atmosphere inside kiln. Check the main burner fuel flow. May be showing normal value and actual more.
Check Cooler air flows.
If you check these values and every thing is in range then increase oxygen content in kiln inlet and see the effect.

Best of luck.

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