Ultrasonics for Monitoring of Mining Mill Linings: Pilot Experiments
2016 (English)Report (Other academic)
Mining mill linings are continuously exposed to wear induced by the charge, and thus, mill operation has to be interrupted on a regular basis for inspections. Stoppages due to inspections and replacement of linings lead to large production and monetary losses; especially in case of unplanned corrective maintenance. Condition monitoring during mill operation can assist in the maintenance planning and decision process to increase the availability and the overall performance of the material processing.In this pilot study, the feasibility of using waterflow ultrasonics for condition monitoring of the lining of mining mills during operation is to be investigated. The proposed waterflow ultrasonic technique uses a water beam to transmit the ultrasound to the mill shell and lining. By measuring the time of flight (TOF), it can be possible to monitor the thickness of mill linings, without the need of interrupting operation. The method can lead to significant energy and monetary savings by reducing inspections and corrective maintenance stoppages, and possibly increase product quality by optimised performance.Since steel has a very high acoustic impedance in comparison to rubber, TOF measurements on aluminium-rubber has been used as an intermediate step towards the goal of measuring steel-rubber combinations. TOF measurements of aluminium-rubber layers have been achieved, and advancement towards the understanding of TOF measurements in steel-rubber laysers have been achieved.The following conclusions have been reached:- Rubber thickness can be measured through aluminium. In practice, aluminium plugs/rivets can be mounted on the steel shell of a mill to measure TOF of rubber shell plates and lifter bars.- Ultrasound signals can be measured through steel-rubber layers in through-transmission and pitch-catch set-ups.- Ultrasound signals measured in pulse-echo or pitch-catch set-up on a solid steel plate connected to rubber, give rise to reverberations (ringing signal) that mask the rubber backwall echoes. For avoiding reverberations of steel plate sides, an experimental set-up requires the steel plate to be at least eight times wider and deeper (x- and y-axis) than the thickness (z-axis) of the rubber under inspection.Keywords: ultrasonic testing, mining mill lining, lined pipes, NDT, condition monitoring, comminution, non-destructive testing, thickness gauge.
Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2016. , 44 p.
Research report / Luleå University of Technology, ISSN 1402-1528
Research subject Operation and Maintenance
IdentifiersURN: urn:nbn:se:ltu:diva-23514Local ID: 741f7a24-f4e9-4bbc-80b9-7c99e0d2b919ISBN: 978-91-7583-609-6ISBN: 978-91-7583-610-2 (PDF)OAI: oai:DiVA.org:ltu-23514DiVA: diva2:996563
ProjectsSquirter Ultrasonic Thickness Gauge for Monitoring of Mining Mill Lining During Operation (SV: Mätning av tjocklek på kvarninfodring med ultraljud under drift)
Godkänd; 2016; 20160503 (chrste)2016-09-292016-09-29Bibliographically approved