Rota de processo para concentração de minérios de ferro hidratados

Abstract

The beneficiation of iron ore is moved by the mineralogical characteristics, texture, structure and physic-chemistry. A specific ore may require modifications to the current concentration techniques so that there is no literature on the subject. Some mines of Vale have lithotypes with peculiar characteristics which influence the quality of the final concentrate of iron ore. These characteristics, especially observed in goethitic ores are the high porosity and high levels of contaminants such as Al2O3, P, Mn, PPC, etc. This study aims to develop an innovative process route to reduce the negative influence of hydrated minerals, mainly the goethitic ones, in the quality of an iron ore concentratewith high grade. This issue increases in importance with the external market demand of high quality especially in times of global crisis. Samples were collected in the area of Project Apolo and separated into rich, goethitic and blending. The steps of mineralogical characterization and the test works were carried out and the tests were divided based on the 0.15 mm size, ie steps of generating sinter feed and pellet feed. Forcomparison reasons the data from the Apolo Project from Vale were used. For the stage of sinter feed stage, the conclusion was that the process route adopted by the project is the best one and such project should keep the original conception. An attrition test work prior to the desliming stage was performed without satisfactory results. In the stage of feed pellet generation, it was confirmed that the conventional flotation must be divided into coarse and fine circuits, ie below 0.15 and above 0.045 mm and below 0.045 mm, this division should provide a gain of 2% in the mass recovery of the final concentrate without quality losses. Beyond the sample taken from the first pellet feed generationstage, test works with other samples with different levels of hydration were carried out using the pH 7, sodium sulfate as activator of the hematite surface, heating the slurry at 85oC to reduce the surface tension and to improve the bubbles stability and ultrasound was also tested in order to expulse ultrafine particles from the porous interstices of larger particles. So it was demonstrated that it is possible to float hematite and increase by about 0.5% in the Fe percentage points in the final concentrate but further and deeper studies must be conducted in this line.