Re: Excess O2 & Boulder Formation

Dear Mr. Ted,

Thank you very much for your quick response...

sulfur/alkalis ratio in hot meal is around 0.3 , sulfur in coal is very low and we dont have raw material source to compensate sulfur shortage.

LSF for kiln feed is 100 - 105

SO3 0.4 % in clinker

MgO 2 - 3 % in clinker

K2O 0.51 % in clinker

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Re: Excess O2 & Boulder Formation

Hello Emad,

From your information above it does not look like sulphur or alkalis are an issue. The MgO is a little high, but not abnormal, so that should not cause an excessively dusty kiln either.

The only thing I can recommend is lowering the SR and increasing the AR, as I said earlier.

Regards,

Ted.

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re Re: Excess O2 & Boulder Formation

Hey Ted; I have read your answer to Emad about dusty clinker and would ask you if there is any relation between AR & SR and low letter weight (< 1050 gr/lt) althogh the free lime is in normal range (1.0 to 1.5%.). Increasing the gas improve the liter weight but at the same time reduce the free lime to less than 0.5 which create an other problem of snowman formation. Since long time we are facing this problem in one of our production line ( kiln with 5 stages PH, PC, & Bypass) and till now we couldnt solve it !!!

Regards

Kiln Feed:

AR:1.55

SR:2.55

MgO:1.92

SO3: 0.3

Na2O: 1.92

K2O: 0.64

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re Re: Excess O2 & Boulder Formation

Hello Nael,

If your free lime is in the normal range, why do you need to increase the litre weight? Litre weight is only a tool to help control free lime.

Is your kiln very dusty? If it is, there may not be any useful relationship between clinker free lime and litre weight.  A dusty kiln can produce well-burnt clinker which has a low/normal free lime but at the same time has a low litre weight. This is because the density of the clinker nodules is reduced by an outer 'spongy' void-filled layer (~2-3mm) caused by binding of dust with melt phase bridges on the surface of the nodules as they pass through the dusty burning zone.

The kiln feed chemistry you have given me does not appear to be too problematic with regard to dust generation. However, even if the sulphur/alkali ratio in your kiln feed is optimal, a low O2 at the kiln inlet can promote excesssive sulphur recirculation, which in turn may result in a dusty burning zone. (An excess of oxygen is required to bind the SO2 and K2O/Na2O chemically in order for sulphur and alkalis to leave the kiln as the less volatile sulphates. eg;- SO2(g) + K2O(g) + ½ O2(g) --> K2SO4(s) )

Hope this helps...

Regards,

Ted.

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