Análise de falha da grelha dupla de descarga do moinho semi-autógeno (SAG) da Mina do Sossego

Abstract

This work deals with the failure analysis grid double discharge of the mill semiautogenous (SAG) of the copper mine of Sossego, located in Canaã dos Carajás-PA. The metal used for making the grate is a low alloy steel Cr-Mo (chrome-molybdenum) that has mechanical characteristics appropriate to the type of service requests and is production from the process of casting sand mold. This grate is responsible for the classification of the ore particles and part of the inner lining of the mill, which has characteristics of resistance to wear and impact and is used to contribute to grinding the ore being one of the minor components life and greater exchange of equipment. The failure occurred during grinding the ore in SAG mill, causing an unscheduled stop for equipment maintenance, since it could not continue operating without proper repair. In this investigation were used techniques of metallographic characterization, such as optical and electron microscopy, chemical analysis, tensile, impact and microhardness testing. The experimental work has allowed the identification the cause failure. The results obtained by the analysis indicated that the failure occurred by fatigue, characterized by the shape and morphology of surfaces of failure, caused by the presence of casting defects in the play as porosity and cavities formed by gases and inclusions.