The most common cause of dusty clinker is excess sulphate over alkali in clinker. High sulphate cycling in the kiln can be caused by reducing burning conditions. Low back-end O2 would be a symptom of that. The ring in the kiln may be the cause of the low draft, therefore reducing conditions and possible high sulphate content. Alternatively it might be a sulphate based ring and therefore a symptom of the problem. Attempts should be made to balance sulphur and alkali inputs to the kiln and a high momentum flame must be maintained at the main burner of the kiln.
Best regards
Dr Michael Clark