we have been experiencing frequent blockages of cyclone no 2 of the kiln. the builduo tends to form just above the cone and collapses and blocks the material chute...often resulting in kiln stoppage. we have seen elavated air temps from this cyclone 650degC and 430degC for Cyclone 1 respectively. s/a ratio of Cyaclone 2 material is around 1.2-1.3. chlorides are very low. what could the cause of this problem be? possible ways out of this? the kiln tube is quite clear with minimal coating