Avaliação do adensamento de rejeitos finos de minério de ferro e sua associação com a mineralogia

Abstract

The lifetime of dams or open pits for tailings disposal is one of the issues addressed in the context of geotechnics applied to mining. The control is periodic, and may have a high frequency (daily), depending on the operational phase. However, the uncertainties and inaccuracies in the calculation of the remaining capacity and, consequently, of lifetime, may have errors obtained with scales larger than the value of the variable "time" as a result. The major uncertainties are in determining an equivalent specific density and dry weight range of tailings conveyed. The inaccuracies are derived from the planimetric-altimetric surveying or bathymetry and disregarding effects consolidation of the waste deposited over time with increasing level of stress for lifting the tailings layer. This work aims at presenting reviews of the influence of the effects of consolidation of the tailings deposited in the reservoir capacity increment used for deposition of thin iron ore tailings, or "overflow" of the cyclone. And to evaluate the consolidation of the "overflow", HCT (Hydraulic Consolidation Test) were performed varying the cutoff mass for the cyclone "underflow", impacting directly on the particle size and density of the grains that are directed to the "overflow". To better understand the results of consolidation also mineralogical analysis were made by light microscopy and chemical by particle size. The results achieved in laboratory tests showed that the reduction in void ratio (consolidation) is directly linked to the initial permeability and to the reduction capacity of this permeability. One can also observe the influence of particle size, since samples with larger variations in particle size had larger reductions in void ratio and permeability.