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Clay mineral reactivity

Ask Dr ClarkCategory: PyroprocessingClay mineral reactivity
Songul Bilge asked 2 years ago

I want to ask a question about the burnability and effect of clay minerals on burnability. We had a problem at kiln 2-3 weeks ago. We had difficulty for burning of the clinker. Our kiln is normally working at 360-370 t/h kiln feeDuring the problem time, we could not increase feeding rate over 330 t/h with high free lime. Clinker was very dusty also.
We checked all the parameters (analysis, equipment, burner adjustments, coal composition and values, kiln coating. During that time, we switched a new type clay. According to XRF measurements, ıt is not possible to make any comment. But when we measure samples with XRD, mineralogical composition is very different. After we changed clay from yellow to gray, kiln and clinkerization turns back to normal.
Now we want to understand the effect of clay minerals on the burning condition of kiln.

2 Answers
Whitehopleman Staff answered 2 years ago

I suspect the problem is the calcite content of the yellow clay. The symptoms also sound very like high sulphur recirculation problems (high free CaO and dusty clinker). Probably the difficulty to combine and low feed rate resulted in over-burning.
What is the sulphur balance of the kiln? Do you have hot meal analyses from the time of the problems?

Whitehopleman Staff answered 2 years ago

I suspect the problem is the calcite content of the yellow clay. The symptoms also sound very like high sulphur recirculation problems (high free CaO and dusty clinker). Probably the difficulty to combine and low feed rate resulted in over-burning.
What is the sulphur balance of the kiln? Do you have hot meal analyses from the time of the problems?