Avaliação do processo de flotação para diferentes frações granulométricas

Abstract

Different sizes of particles are found on the flotation processes for the iron ore industry nowadays. Industrial practice and the results of investigations have shown the hardness to recovery small particles of iron ore minerals, below 0,045mm, resulting in high iron contents on the flotation waste. The behavior of coarse and fine particles (separately) of an itabiritic ore with low iron degree were investigated during this work through bench scale tests in mechanical cell flotation. At first, the global fraction -0,150mm, after deslimed, was classified through bench scale sieving aiming the obtention of the fractions +0,045mm and -0,045mm. These two fractions and the -0,150mm global were submitted to the first flotation tests to evaluate the effect of amine and starch dosages, pH and rotation during conditioning values. These tests were carried out using design and analysis of experiments methodology with two levels and four variables, summing 16 tests for each size fraction. The second stage of this work was realized with coarse (55% +0,045mm) and fine (85% - 0,045mm) particles obtained by pilot scale ciclone of the -0,150mm global, aiming the investigation of amine dosage, pulp percent of solids and residence time during rougher, cleaner and scavenger stages. The results showed different behaviors for coarse and fine particles on the flotation process, where the coarse particles showed high sensibility to the variations of reagents dosages, pH value and rotation during conditioning. In adition, the separate flotation indicated the possibility to encrease metallurgical recovery close to 3%, mainly do the low iron degree on the waste of the coarse particle´s flotation. The separate flotation showed higher amine dosages and bigger residence times compared to the flotation of fine and coarse together.