These pulleys have a 3600 mm face width and the original applicators have chosen to cut and join shorter strips to cover the 3600 mm pulley. This places a weak point midway across the pulley and greatly increases the risk of a lagging failure. Strip pulley lagging must always be applied as strips that cover the full pulley face width in a single piece.
Elastotec supported PROK to urgently manufacture the 3800 mm long ceramic lagging strips for the four pulleys and had this shipped, with the Elastotec cold bonding system, by airfreight to the mine site. An Elastotec applications engineer was sent to the site to assist with training, and supervision of the lagging application – duplicate adhesion tests were carried out on each pulley lagged, and the results were above the Elastotec requirement of a minimum of 12N/mm. The pulleys are back online and are operating satisfactorily.
The limitations of cold bonded lagging are well documented and result from moderate adhesion strength under the best of conditions and variability in application techniques and applicator knowledge.