We are experiencing a ring at the 5-7m mark from the outlet after running the kiln for about a week. Our kiln is 50m ling and 3.8m diameter. Kiln feed fineness is around 19% residues on 90micron sieve, there has been no change in alkali and sulfur content. What could be the cause of the ring? and how can we distingnguish between a sulphur, spurrite and alkali ring. Can somebody recommend some literature on ring formation, causes etc?

thank you

Are you still experiencing this ring formation Naison? At that position the root cause is most likely excessive SO3 circulation. Have you tested the hot meal SO3 (and chloride)? Adjustment of the main burner and ensuring good combustion of the fuel there is the most likely solution.

Dr Michael Clark

A ring was beginning to form just before we stopped the kiln  due to snowman built up in the gratecooler .I had not done an SO3 analysis in the hot meal but I have taken note of your advise, currently we are analyzing clinker SO3 at 2 hour intervals. Would that not give an indication of a sulphur built build up? The SO3 in clinker is ~1.3%

No Naison, the SO3 content of clinker will not tell us the degree of SO3 concentration or potential build-up formation. We have to have the concentration in the hot meal.

Dr Michael Clark

I don't know if you are still having ring issues, but at that section of the kiln I highly doubt it is Sulfur issue. It is simply too hot at 1.3-1-8 diameters up the kiln to have sulfur condensing.  This is actually where you would be vaporizing the sulfur in the meal and it would build a ring further up th kiln in the 30-40 m range.  You would also have a large amount of buidup in the riser.  I would look at the liquid in the feed and more importantly the A/F ratio.  You can have similar liquid % with totally different coatibilities based on the A/F ratio.  If you are below 1.0, then I would think that is one of the issues.  Flame could also be an issue, but I would look at the liquid especially since you are building snowmen in the cooler.  That means the clinker is not quenched in the kiln and is still in some form of a liquid phase as it enters the cooler.

Good luck

Dear ncchirwa@sinozi.co.zw

I don't know have you still any problems with rings. I can answer you I don't thing, that 1,3% of sulfur (in clinker) can brings to ring formation. I absolutely agree with Dirt Burner's opinon and tell you, that you must calculate ASR ratio. This can help you. You also can take chemical analyse of normal coating and save it. When rings are rising you can analyse the ring as well, and compare the two analyses. This statistics will help you for further orientation.

With regards, David.