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.

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

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.