Dear Mr.Ted Karpet,

Thanks for sharing your experience.Since the conditions that lead to ring formation and consequently kiln charge ball formation rarely be changed the appropriate solution is to be destablised the ring as it forms.One possible remedial measure is to install a silicon-carbide based alumina bricks,which create inert brick surface,reduces formation of rings in upper transition zone.Main root cause of formation of kiln ring and subsequent boulder formation results of molar ratio imbalance.In your case cause of ring formation is excess sulfur than alkali and in my case there is excess sulfur deficiency or excess alkali.If we can attempt to balance the molar ratio than most probably ring formation problem in kiln can be solved.Of course a strong flame or high flame momentum is precondition for stable kiln operation of any kiln.

Regarding use of Silicon carbide base refractory use,I would like to invite viwes of  refractory experts of the forum .