xxxx
232 posts
TimePosted 10/01/2013 06:03:01
xxxx says

clinker nibs

Dear All

How nibs of clinker is formed in acement mill particularly in open ckt mill why not in close ckt with the same quality clinker?

what are the quality parameters in clinker responsible for the nibs formation?

Does high free lime clinker gives nibs formation ?

Is high free lime clinker is harder to grind?

Please do explain

Engr

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Ted Krapkat
536 posts
TimePosted 14/01/2013 05:17:50

re clinker nibs

Hello XXXX - Engr,

Clinker with high free lime is normally easier to grind because it is softer than dense, hard burned (low free lime) clinker.

If you are getting this problem in two different mills using the same clinker, it is likely that the cement mill with the problem has a lower grinding efficiency than the other mill.

Open circuit mills are more likely to have this problem because they are a one pass system and whether the clinker nodules are broken up and ground sufficiently can depend on the hardness of the clinker as well as the upper nodule size.

 

Regards,

Ted.

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xxxx
232 posts
TimePosted 14/01/2013 07:21:00
xxxx says

re clinker nibs

Dear Mr. Ted

 

Thanks a lot for the reply but my experience is just opposite with respect to free lime in clinker & mill production.

Some time back we faces a lot of problem of high free lime in clinker ( increased to 3.5% from 1.5%) & we observed that our both mill productions reduced by 15-20% . One mill is open & the other is closed ckt.

I think with high free lime content in clinker the C2S increases which results in poor grindiability & less production.

Please do comment if I am wrong.

Thanks

 

ENGR

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Ted Krapkat
536 posts
TimePosted 15/01/2013 02:09:42

re clinker nibs

Hello XXXX - Engr,

This topic has been discussed before at the following thread;-

http://www.cemnet.com/Forum/thread/108976/impact-of-free-lime-on-grinding-efficiency.html

 

It is pretty much generally accepted that (all else being equal) soft-burned clinker is easier to grind than hard-burned clinker. So your observations to the contrary must have another cause.

I suspect that it might be due to dusty clinker. High free lime clinker can result in a lot of dust entering the ball mill with the clinker. An excessive amount of fine particles tend to agglomerate and coat the balls, thus preventing direct ball-to-clinker particle impact and reducing the grinding energy being delivered to clinker particles. This will result in a reduction in throughput and/or potentially producing unground clinker nibs.

Coating of the balls with dust can be prevented using a Triethanolamine (TEA) or gylcol based grinding aid.

 

Regards,

Ted.

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