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Leaching Behavior of Metals and Sulfate from Taconite Tailings Used in Pavement Construction
Taconite tailings are the by-product ore-bearing rocks of iron mining, predominantly consisting of silicate and fine magnetite crystals. In recent years, the use of taconite tailings in pavement construction has increased considerably due to their superior mechanical properties. However, an environmental impact assessment of taconite tailings is required before their potential use in construction purposes. Taconite tailings may leach heavy and toxic metals, which could contaminate the soil, surface, and groundwater. Coarse, sand, fine, and composite sized taconite tailings were subjected to pH-dependent leaching tests in the pH range of 2 to 13 to investigate the leaching behavior of aluminum (Al), chromium (Cr), magnesium (Mg), and sulfate (SO4). In addition, toxic characteristic leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), water leach test (WLT), and U.S. Geological Survey (USGS) leach tests were performed to evaluate the leaching behavior of taconite tailings in different environmental conditions. The test results showed the highest concentrations of metals were leached from fine sized taconite, whereas the lowest amounts of metal leached from composite taconite tailings. Al and Cr demonstrated amphoteric leaching patterns, whereas Mg showed a cationic leaching pattern. The leached concentrations of SO4 were found to be pH-independent at the pH range of 4 to 13. Except for Al, the leached concentrations of other elements were below the U.S. EPA specified maximum contaminant levels (MCLs) for drinking water. Taconite tailings leached the highest metal concentrations in TCLP effluent; therefore, it is recommended as the most conservative test procedure to evaluate the leaching of these metals from taconite tailings.
Leaching Behavior of Metals and Sulfate from Taconite Tailings Used in Pavement Construction
Taconite tailings are the by-product ore-bearing rocks of iron mining, predominantly consisting of silicate and fine magnetite crystals. In recent years, the use of taconite tailings in pavement construction has increased considerably due to their superior mechanical properties. However, an environmental impact assessment of taconite tailings is required before their potential use in construction purposes. Taconite tailings may leach heavy and toxic metals, which could contaminate the soil, surface, and groundwater. Coarse, sand, fine, and composite sized taconite tailings were subjected to pH-dependent leaching tests in the pH range of 2 to 13 to investigate the leaching behavior of aluminum (Al), chromium (Cr), magnesium (Mg), and sulfate (SO4). In addition, toxic characteristic leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), water leach test (WLT), and U.S. Geological Survey (USGS) leach tests were performed to evaluate the leaching behavior of taconite tailings in different environmental conditions. The test results showed the highest concentrations of metals were leached from fine sized taconite, whereas the lowest amounts of metal leached from composite taconite tailings. Al and Cr demonstrated amphoteric leaching patterns, whereas Mg showed a cationic leaching pattern. The leached concentrations of SO4 were found to be pH-independent at the pH range of 4 to 13. Except for Al, the leached concentrations of other elements were below the U.S. EPA specified maximum contaminant levels (MCLs) for drinking water. Taconite tailings leached the highest metal concentrations in TCLP effluent; therefore, it is recommended as the most conservative test procedure to evaluate the leaching of these metals from taconite tailings.
Leaching Behavior of Metals and Sulfate from Taconite Tailings Used in Pavement Construction
Schreck, Samuel (author) / Mahedi, Masrur (author) / Cetin, Bora (author)
Geo-Congress 2020 ; 2020 ; Minneapolis, Minnesota
Geo-Congress 2020 ; 159-168
2020-02-21
Conference paper
Electronic Resource
English
Leaching Behavior of Metals and Sulfate from Taconite Tailings Used in Pavement Construction
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