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<p>As mining activities result in increased volumes of tailings storage and extended storage durations, technologies for tailings solidification, backfilling, and in-situ reinforcement face challenges posed by acid mine drainage. This study investigates the mechanism of sulfuric acid attack on AAMs used for solidifying tailings, focusing on changes in hydration products and microstructural evolution across different curing stages. Short-term (3-day) acid immersion tests revealed that AAM paste specimens maintained structural integrity with a slight strength increase, whereas AAM-solidified tailings experienced strength reduction due to the dissolution of tailings constituents. Microscopic analysis indicated that early-stage hydration products (C-S-H, C-A-H, and CH) were susceptible to acid-induced degradation, leading to pore formation. In later stages, aluminum incorporation transformed C-S-H into more stable C-(A)-S-H, forming reinforced networks that enhanced acid resistance. The acidic environment promoted gypsum crystallization via CH hydrolysis, filling macropores and densifying the microstructure temporarily. However, long-term exposure risks gypsum overgrowth, causing damage to the gel network and microstructural integrity, which requires further research. Ultimately, this work provides critical insights for promoting sustainable mining practices, improving tailings management, and strengthening environmental safeguards.</p>

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Effects of sulfuric acid on AAM-solidified tailings during hydration

  • 期刊论文

  • 发表日期：

    2026年1月13日

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  • Xueqiao Han,
  • Chao Zhang,
  • Changkun Ma,
  • Hao Liu,
  • Zhenkai Pan

摘要

As mining activities result in increased volumes of tailings storage and extended storage durations, technologies for tailings solidification, backfilling, and in-situ reinforcement face challenges posed by acid mine drainage. This study investigates the mechanism of sulfuric acid attack on AAMs used for solidifying tailings, focusing on changes in hydration products and microstructural evolution across different curing stages. Short-term (3-day) acid immersion tests revealed that AAM paste specimens maintained structural integrity with a slight strength increase, whereas AAM-solidified tailings experienced strength reduction due to the dissolution of tailings constituents. Microscopic analysis indicated that early-stage hydration products (C-S-H, C-A-H, and CH) were susceptible to acid-induced degradation, leading to pore formation. In later stages, aluminum incorporation transformed C-S-H into more stable C-(A)-S-H, forming reinforced networks that enhanced acid resistance. The acidic environment promoted gypsum crystallization via CH hydrolysis, filling macropores and densifying the microstructure temporarily. However, long-term exposure risks gypsum overgrowth, causing damage to the gel network and microstructural integrity, which requires further research. Ultimately, this work provides critical insights for promoting sustainable mining practices, improving tailings management, and strengthening environmental safeguards.