Influência de características químicas e físicas no teor de umidade e TML de minérios de ferro da Serra Azul – MG

Abstract

This study aims to study the main relationships between the chemical and granulometric characteristics of Pellet Feed iron ores from the Serra Azul – MG region, identifying the main influences on their moisture content and TML (Transportable Moisture Limit). The control of moisture content in iron ores is of great importance in mining, as high levels can negatively influence the performance of raw materials in the processes of the plants where they are destined, in addition to causing problems during their road and rail transport. In addition, this characteristic is currently gaining great prominence due to the heating up of maritime transport of this commodity, since to make such transport viable, avoiding maritime accidents caused by cargo liquefaction in the holds of ships, it is essential to control the moisture content in a maximum limit. The first stage of the study consisted of collecting the results of chemical, physical, moisture content and TML analyzes of all shipments of iron ore concentrates of the Pellet Feed type, in the period between August 2017 and October 2020, from a same mining company located in the Serra Azul region – MG, totaling 46 loads. Then, a descriptive statistical analysis was performed using Minitab Software, with the objective of knowing and summarizing the numerical data collected. After this step, data processing, investigation of the correlation between independent variables and dependent variables were carried out, as well as an analysis of simple and multiple regressions, in order to confirm the results obtained. From the analyzes performed, it was found that, specifically for the analyzed ore, the content of contaminants (TC), composed of the elements P, Mn and PPC, represented the variable with the greatest influence on the TML results, which is explained by the association of these contaminants with goethite, an ore that has high porosity and, therefore, a high degree of voids. For moisture, the most influential variable was the percentage of particles with a size <0.045 mm, due to the fact that retained moisture is directly proportional to the contact area between water and particle. It was also possible to conclude that the P, Mn and PPC elements have a positive correlation with each other and a negative correlation with the Fe element, particles with size <0.045mm tend to have a higher percentage of contaminants and that the SiO2 content did not show any correlation even with the humidity and neither with TML. These results can collaborate as support material in the decision-making of iron mining companies located in the Serra Azul region, serving to give direction in analyzes and discussions, and contributing to the guarantee of adequate specifications for the maritime transport of these ore products.