Abstract:The permeability characteristics of iron tailings are one of the important factors affecting the stability of the tailings dam. The permeability properties of undisturbed iron tailings and disturbed iron tailings were analyzed from various aspects such as FC value, gradation, particle size, specific surface area, and interparticle void ratio with water head test in laboratory. The results show that the permeability coefficients of undisturbed iron tailings and disturbed iron tailings are affected by the fine p… Show more
Understanding the influence of soil microstructure on light non-aqueous phase liquids (LNAPLs) behavior is critical for predicting the formation of residual LNAPLs under spill condition. However, the roles of soil particle and pore on LNAPLs migration and residue remains unclear. Here, the experiment simulated an LNAPLs (diesel) spill that was performed in fourteen types of soils, and the key factors affecting diesel behavior are revealed. There were significant differences between fourteen types of soils, with regard to the soil particle, soil pore, and diesel migration and residue. After 72 h of leakage, the migration distance of diesel ranged from 3.42 cm to 8.82 cm in the soils. Except for sandy soil, diesel was mainly distributed in the 0–3 cm soil layer, and the residual amounts were 7.85–26.66 g/kg. It was further confirmed from microstructure that the consistency of soil particle and volume of soil macropores (0.05–7.5 μm) are important for diesel residue in the 0–1 cm soil layer and migration distance. The large soil particles corresponding to 90% of volume fraction and volume of soil mesopores (< 0.05 μm) are key factors affecting diesel residue in the 1–3 cm soil layer. The result helps to further comprehend the formation mechanism of residual LNAPLs in the soil.
Understanding the influence of soil microstructure on light non-aqueous phase liquids (LNAPLs) behavior is critical for predicting the formation of residual LNAPLs under spill condition. However, the roles of soil particle and pore on LNAPLs migration and residue remains unclear. Here, the experiment simulated an LNAPLs (diesel) spill that was performed in fourteen types of soils, and the key factors affecting diesel behavior are revealed. There were significant differences between fourteen types of soils, with regard to the soil particle, soil pore, and diesel migration and residue. After 72 h of leakage, the migration distance of diesel ranged from 3.42 cm to 8.82 cm in the soils. Except for sandy soil, diesel was mainly distributed in the 0–3 cm soil layer, and the residual amounts were 7.85–26.66 g/kg. It was further confirmed from microstructure that the consistency of soil particle and volume of soil macropores (0.05–7.5 μm) are important for diesel residue in the 0–1 cm soil layer and migration distance. The large soil particles corresponding to 90% of volume fraction and volume of soil mesopores (< 0.05 μm) are key factors affecting diesel residue in the 1–3 cm soil layer. The result helps to further comprehend the formation mechanism of residual LNAPLs in the soil.
“…2-1, 2-2, and 2-3 belong to the first type of iron tailings. eir permeability could be calculated by equation (21). e results are shown in Table 1, which becomes more accurate.…”
Section: Permeability Coefficient Calculation Of the Disturbed Tailinmentioning
confidence: 96%
“…But the permeability coefficients increase slightly, when the silt content exceeds 40%. e reason behind this increasing trend is that the void ratio increases when the silt content exceeds 40% [21]. en, the permeability coefficients continue to decrease because of the increase in clay content.…”
Section: E Influence Of Fine Particle Content On Permeabilitymentioning
confidence: 99%
“…Benson et al [29] believe that the permeability coefficient fell off rapidly when the fine content exceeds 40%, which is similar to the test results in Section 3.1. e calculation formula for FC th (the threshold of FC) used to calculate the FC th of iron tailings was proposed by Rahman et al [28]. e FC th of iron tailings is approximately 40% [21]. erefore, the iron tailings could be classified into two categories according to the FC th .…”
Section: Tailings Classificationmentioning
confidence: 99%
“…erefore, n should give place to n silt . d 10 is used to calculate the average pore diameter of silt [21]. e permeability of the second iron tailings (2-4) could be calculated by equation (22), and more accurate results were obtained and are shown in Table 1:…”
Section: Permeability Coefficient Calculation Of the Disturbed Tailinmentioning
The stability of iron tailings dam is affected by the permeability of tailings. Considering the influence of it, it is necessary to analyze the permeability of tailings so as to prevent the recurrence of Brazilian iron tailings dam accidents. Nevertheless, the results of iron tailings permeability from some prediction equations (Terzaghi equation, Hazen equation, and Kozeny equation) cannot be accurate. Iron tailings are various as they can be divided into three categories: (1) silt content is less than 40%; (2) silt content is more than 40%, while clay content is less than 15%; and (3) clay content is more than 15% and less than 30%. Correspondingly, three equations are proposed to calculate the disturbed and iron undisturbed tailings permeability for the three types. And more accurate results come from it. The water-flow paths of the iron tailings are blocked after compaction, and the critical pressure of iron tailings blockage is 200 kPa. Although the porosity is large, some of the pores are isolated from each other when the pressure is larger than 200 kPa. However, porosity becomes too large for permeability calculation after compaction and the calculated permeability gets larger as well (equations (24)–(26)). Correcting the permeability calculation equations is an absolute must. The calculated permeability by the revised equations becomes more accurate (equations (27)–(29)). In fact, the granulometric characteristics necessarily play a vital role in the evolution of the pore interconnections by blocking the water-flow paths and modifying the morphological parameters. More research studies are required to be done in the future.
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