Estudo sobre coletores na flotação catiônica reversa de minérios de ferro itabiríticos

Abstract

In 2010 the Brazilian iron ore reserves accounted for 18.1% of the worldwide total (fourth position in relationship to the world). In the same year Brazil was the second biggest exporter of iron ore in the world, driven, mainly, by China's economic growing. The commodity cost has reached prices higher than those offered in previous years making this an extremely profitable business. Samarco is one of the major Brazilian companies producing pellets, from pellet feed, for the foreign market and the principal unit operation to concentrate the iron ores is flotation. The flotation process uses several reagents as collectors to increase the grade of iron in the ores. The collectors employed at Samarco are ether monoamine and ether diamine. The ether amines are produced by addition and hydrogenation reactions and are used in flotation neutralized with acetic acid to produce salt in solution and thus increasing the solubility of reagents. The solubility of these amines depends on factors such as pH of the solution and the length of the hydrocarbon chain. Samarco efficiently utilizes the combination of ether monoamines and diamines in flotation and in 2006 the expenses with amines represented 45% of the consumables total. The amines may be characterized by infrared spectroscopy, which generate transmission spectra with the characteristic bands of each group present in the reagent and also by high performance liquid chromatography, which generate mass spectra with the ratio mass/charge of ions in the reagent. To quantify the concentration of amine solution the colorimetric technique is used based on the color variation of a system due to the modification of the reagent concentration. There is also a series of analytical methods for quality control of the amines, useful to check the specifications of the products supplied by the manufacturers.