We frequently face with ball formation problem in the kiln for two months. We are studying the case and investigating the parameter changes. What are the possible reasons and the explanation of this phenomenon?

There are two potential causes that I would investigate:
(i) a change orvariability in the MgO content of your kiln feed, and (ii) a change or rise in the Mn2O3 content of your kiln feed.

How can we solve the nose ring formation at the kiln? Any help much appreciated.

The most likely solution will be to adjust the main burner of the kiln neither by changing the position in the kiln by pushing the burner in or pulling it out a little. Alternatively adjustment of the axial and radial air settings might solve the problem. All these adjustments should be done cautiously and one at a time at sufficient intervals to fully evaluate the effects of the adjustments. There is potential to adversely affect the clinker quality or damage the refractory lining therefore only make small changes before evaluating the effects.