Avaliação dos mecanismos da corrosão interna no mineroduto do Projeto Minas Rio e de formas de sua mensuração

Abstract

According to the Brazilian Institute of Mining, the activity of ore extraction is one of the basic sectors of the Brazilian economy and attracts a lot of investment. Mining has the capacity to supply products to various types of industries such as steel, petrochemicals, and metallurgy. Due to the role that mining plays in the economy, it is important to worry about the forms of transport for these products. One of the important forms of transport used for mining products is the pipeline, which in many cases is used to transport iron ore. In this context, the life span of the pipeline is influenced by corrosion, which can compromise the mechanical integrity of the system with a possible loss of wall thickness and formation of cracks. To monitor the advancement of the corrosion process in the pipeline and considering that there are no methods which are completely fundamental, to quantify the corrosion rate electrochemical tests were conducted with pulp and process water and analysis of cupons installed along field. The product of corrosion found on the surface of the cupons and the material collected during the passage of the cleaning PIG was characterized using chemical analysis, granulometric analysis and X-Ray Diffraction (XRD). It was verified that some cupons had intensive corrosion on the surface verses, what was not expected, the results being inconsistent. It was noticed the anticipation of the breakdown of the passive layer of the steels immersed in the supernatant waters of the pulps collected in some points. This anticipation is related to the greater susceptibility to localized corrosion. Some common corrosion products of carbon steel were identified, such as hematite, goethite, magnetite and their respective variations.