Hydraulic Characteristics of Silt-Sized Iron Ore Tailings

Stacked tailings have become increasingly popular in recent years as a more environmentally friendly option for tailings disposal. However, the design and assessment of stacked tailings present unique challenges due to their unprecedented heights and the wide range of factors that affect their behavior, including particle types and sizes, environmental and operational conditions, and post-compaction states. To further understand their behavior, this paper presents a comprehensive characterization of the geotechnical and hydraulic properties of three iron ore tailings (IOT) samples, exploring how their water retention characteristics and hydraulic conductivity are affected by the tailings’ variability and void ratio. Using the filter paper method and constant head tests in a flexible wall permeameter, the water retention characteristics and hydraulic conductivity were obtained. Chemical-mineralogical composition and microstructural analyses were conducted using X-ray diffraction and scanning electron microscopy couple with energy dispersive spectroscopy. The results revealed that slight variations in particle size distribution can significantly influence the water retention characteristics and hydraulic conductivity of IOT samples. A dual porosity model was used to account for the aggregation of fine particles, and a strong linear relationship between void ratio and both macrostructure and microstructure fitting parameters of the water retention curves was found. Additionally, an exponential function was observed to display how the reduction of void ratio leads to a decrease in hydraulic conductivity. This research provides insight into the distinct properties of IOT and can be used to enhance the design and evaluation of stacked tailings.