Acid Mine Drainage Remediation
Calcium silicate is also a constituent of the slag that is produced when molten iron is made from iron ore and calcium carbonate in a blast furnace. When this material is processed into a highly refined, repurposed calcium silicate aggregate, it is used in the remediation of acid mine drainage (AMD) on active and passive mine sites. Calcium silicate neutralizes active acidity in AMD systems by removing free hydrogen ions from the bulk solution, thereby increasing pH. As its silicate anion captures H+ ions (raising the pH), it forms monosilicic acid (H4SiO4), a neutral solute. Monosilicic acid remains in the bulk solution to play other important roles in correcting the adverse effects of acidic conditions. As opposed to limestone (a popular remediation material), calcium silicate effectively precipitates heavy metals and does not armor over, prolonging its effectiveness in AMD systems.
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