Re: brown core in clinker

it depends of decarbonization? I saw this when decarbonization after preheater was nearly 96-98%. how this brown core impact on klinker quality?

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Re: brown core in clinker

Brown core clinker is expected to have a high free lime hence poor quality.

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Re: brown core in clinker

Bhaskar:

Brown core clinker is expected to have a high free lime hence poor quality.

Bhaskar,

Not always.  It depends on the conditions which have caused the brown cores. Normally these conditions are related to either reducing conditions, or very high temperatures in the burning zone. So, such clinkers will normally have normal or low free lime contents.

The only way to get clinker with brown cores which have high free lime in the centres is for large lumps or slabs of hot-meal buildup to fall into the kiln inlet and break up into smaller lumps as they travel through the kiln. Because these lumps do not form under the normal nodulisation process, the outside shell (10-20mm) of the resultant clinker "nodules" are dark and clinkerized, however the interiors remain unburnt and brown and have very high free lime. 

So, it all depends on which type of "brown core clinker" you are talking about... 'hard brown centres' caused by reduced Fe or 'soft, brown centres' caused by falling slabs of unburnt buildup.

 Regards,

 Ted

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Re: brown core in clinker

Ted Krapkat

 I am very interested in your last answer. We very often have 4 or 5 times per day free lime. According to your answer I can make conclusion that generally free lime in clinker appear (if raw meal was ok in chemical composition) from large lumps or slabs? But what are the reasons of it? How to avoid it?

 Last week we have ‘hard brown centres’.  We made chemical test and it showed 0,12% Fe +2. That time the 4-th cyclone outlet temperature was 900-910oC. What it was? How we can measure temperature in the burning zone and make decision that it was too much?

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