A Review of Bucket Wheel Reclaimer Failure Through Mechanical Test and Metallographic Analysis
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CASE HISTORY—PEER-REVIEWED
A Review of Bucket Wheel Reclaimer Failure Through Mechanical Test and Metallographic Analysis Abhijit Chatterjee • Debashis Das
Submitted: 11 February 2014 / Published online: 11 November 2014 ASM International 2014
Abstract The present article provides description of a catastrophic failure of a Stacker-cum-Reclaimer in one iron ore mining area in India. The failure invited a detailed review into the possible causes of failure through onsite inspection, mechanical testing and metallographic analysis. A review of the collapse structures at site revealed a few critical operational reasons clubbed together with metallographic conditions as the triggering causes of failure. Based on the findings of visual review, mechanical tests and metallographic analysis a few recommendations are made to avoid such failure in future. Keywords Bucket wheel reclaimer Mechanical test Metallographic properties Equipment collapse Unbalance
Introduction Failure of robust mining structure such as bucket wheel reclaimer is not desired due to its huge impact on the production capacity of mines and such failure leads to huge economic losses. Replacement of such equipment is a timeconsuming procedure. It creates bottlenecks of ore production. Failures of mining equipment originate from defect in design, manufacturing and operation etc. [1]. Defects in weld or improper welding process at the time of fabrication [2–6] are a major cause of failure of heavy mining equipment. The entire reclaimer consisted of major sub-assemblies portal A. Chatterjee (&) D. Das CSIR-Central Mechanical Engineering Research Institute, MSEG, Durgapur 713209, India e-mail: [email protected]
frames with travel drive, slew drive impact table, fixed chute and three point support that are the first phase of major component. The second set of major components are slewing frame with slew bearing, pylon, two wall chute, central chute and boom supporting hinges. Third set of components is boom with bucket wheel conveyer, the members and counter weights. The collapse of the bucket wheel reclaimer occurred at the early stage of commissioning during a balancing process. Such structure includes with minimum redundancy during manufacturing. As a result failure of any component may lead to catastrophic collapse of the whole structure. Investigation of the collapse was based on the following aspects (a) Visual review of the collapse structure at site. (b) Examination of the collapse mode of the components (reclaimer, boom, pylon, etc.) (c) Collection of sample for evaluation through mechanical tests (hardness and tensile) and microstructural characterization. (d) Analysis of the operational sequence before the failure. The results of each of these steps of review are described in this article.
Review of the Collapsed Structure at Site From Fig. 1 it is evident that the counter weight boom had got twisted along with damage of other truss members. The boom acts as a tie member between the counter weight and the mast. Bottom of mast joint w
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