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Detailed Investigation of Lime Kiln Mud Ring Formation


September 1, 2010
By Pulp & Paper Canada

Best Supplier Paper, PACWEST Conference, Kamloops, BC, June 9-12, 2010.

Best Supplier Paper, PACWEST Conference, Kamloops, BC, June 9-12, 2010.

Abstract: At a 700 tonne/day lime kiln, rapid ring formation occurred immediately after the chain section over a two day period, causing a mill shutdown. Lime mud solids content remained at 75 to 80 wt% during this event. The ring material was relatively soft and extended for a distance of approximately 20 meters from the chain section. This kiln did not have a history of ring formation. The ring material was examined in detail by X-ray diffraction analysis (XRD), elemental analysis and scanning electron microscope/ energy dispersive x-ray spectroscopy (SEM-EDX). To the best of the author’s knowledge, this type of study has not been previously reported for a kiln ring at this location.

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Results showed that the kiln ring material was formed by growth of calcite crystals that acted to bridge particles and increase compressive strength. The likely reaction mechanism is reactive precipitation of calcite. Kiln precipitator dust recycle was a contributing factor. This mechanism is compared with mid-kiln ring formation that occurs by recarbonation and sintering of calcite crystals. Based on the results, operating conditions of the kiln were modified and ring formation has not recurred.

Paper presented at the 2010 PACWEST Conference in Sun Peaks, B.C., June 9-12, 2010.

Keywords: LIME KILN, RING FORMATION, MUD RING, DUST RECYCLE AND REACTION MECHANISM.

Full manuscript available at www.paptac.ca.


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