Filtragem de Rejeitos de Minério de Ferro Visando a sua Disposição em Pilhas

Abstract

The increased volume of waste generated in the beneficiation of iron ore, driven by the decrease in the metal content in the mineral deposits, has raised interest in studying new methods for their disposal. The traditional method with the disposal of slurry in tailing dams requires large areas, with large environmental impact and thereforepresents a difficulty in acquiring new licenses. Filtration and disposal of tailings in stockpiles may be a viable alternative in this context.Filtration tests in laboratory scale were conducted with tailing's samples of several mills from the Iron Quadrangle. The tests were performed using the main filtering technologies available in the market: vacuum filtration, pressure, hyperbaric and capillary filters. The results showed that with the exception of the slimes, it is possible to filter the tailings from the processing plants with a good filtration rate and a residualmoisture suitable for stacking. The market prices and energy consumption of each equipment was updated and an economic analysis was conducted to verify the most appropriate technology for each application. For the flotation tailings, the best economic alternative is the use of conventional disc filters. However, the energy consumption of filters with ceramic discs is only 15% of a conventional disc filter and could be the best option depending on the variation in energy costs over the period of the project. The slimes can not be filtered by applying vacuum and capillary filtration technologies. The filtration of slimes under pressure or using hyperbaric filters resulted in low filtrationrate and high residual cake moisture (around 20%). The best technical and economical alternative to filter slimes is the use of horizontal filter press, but it is recommended to be carried out bench tests to verify the technical feasibility. The resulting cake could be mixed with the coarse tailings and / or mine waste to facilitate its stacking. A comparative study of three alternative proposals for solid-liquid separation of slimesand flotation tailings of new plants treating poor itabirites was conducted. These alternatives may be innovative solutions to the conventional method of disposal in tailings dams with diluted pulp, although it requires further geotechnical studies.