Wear mechanisms in dense phase pneumatic conveying of alumina

Pipeline wear is a very complex problem and at present there is limited understanding of the wear mechanisms responsible for the reduction of pipe wall thickness in severe wear regions. The ability to determine the wear mechanisms in these areas holds the key in determining the service life of pneumatic conveying pipelines in the industry. In this paper the wear mechanisms in an alumina-conveying pipeline have been studied. Observations reveal that the wear mechanisms in severe wear areas in straight sections are similar to those in the reacceleration zones after the bends. This phenomena lead to the assumption that a core flow bouncing from top to bottom section through the pipeline. The study also revealed that crack formation and delamination of surface layer as dominant wear mechanisms in the severe wear regions which are believed to be effects of work hardening and the formation of transfer film in the internal pipe surface. Visual observation, scanning electron microscopy and laser scanning confocal microscopy have been used as surface analysis tools and results are presented. Finally a generic model is presented which has the potential to predict the wear life of a pneumatic conveying pipeline.