Failure and repair of a mine hoist drumshaft

"Fractures in mine hoist drumshafts are rare. We know of no previously reported attempts to repair a fractured drumshaft; any feasible method would involve welding and the associated problems of distortion, crack formation and strength.In June 1984, a fracture was discovered in the drumshaft of the production hoist in the Teck Corporation, Lamaque Division Mine at Val d'Or, Quebec. Delivery time on a new shaft would have been at least six months. The shaft was repaired in ten days and the total out -of-service time was four weeks.This paper describes why the shaft failed, how it was repaired, and the special alignment procedures employed during re-installation to minimize stresses in the repaired area.IntroductionThe performance of a mine hoist drumshaft is absolutely critical to mine operation. An inoperable drumshaft means no hoist, which in turn means no production or mine operation.Fractures in mine hoist drumshafts are rare. Previously when they have occurred, no one has seriously considered attempting a repair because of problems involved. Any feasible method would involve welding, which raises several major problems - namely, metallurgical, alignment, and strength.In July 1984 this very situation occurred at the Teck Corporation, Lamaque Division Mine in Val d'Or, Quebec.It was recognized that a new shaft would take at least 6 months' fabrication and delivery time. However, having had some experience at repairing broken shafts in other machines under similarly desperate circumstances, and after due consideration, it was concluded that by applying the correct techniques and engaging the right expertise, it would be possible to perform a repair and have the mine back in operation within a month.Thanks to outstanding efforts by all, the repair was accomplished in ten days and total out-of-service-time was only four weeks. The causes of the failure were determined and the calculated stress levels confirmed by strain gauge measurement during operation.The success of this project was achieved by adhering rigorously to fundamental management and engineering principles."