材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
論文
材料特性が異なる酸化マグネシウム系不溶化材による自然由来砒素の溶出抑制効果
高田 孟箱崎 宥哉乾 徹緒方 奨坂本 裕一尾花 誠一森 啓年
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2024 年 73 巻 1 号 p. 70-75

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Downward-flow column percolation tests were conducted for hydrothermally altered rock with a high acidification potential, with and without treatment by two different magnesium oxide (MgO)-based agents to limit the generation of acid drainage and leaching of heavy metals and metalloids with natural origins. Particularly, the effects of the physicochemical properties of the MgO-based agents, such as hydration rate, chemical composition, and specific surface area, on the treatability were evaluated. When the additive content of the MgO-based agent is 5% in dry-mass basis, the agent is consumed in the neutralization reaction for the acid drainage generated by the oxidation of the sulfide minerals, as well as the release of soluble Mg out of the system. Accordingly, immobilization of the arsenic is adversely affected, particularly in the cases in which the soft-burnt granular agent with a low hydration rate is adopted. Whereas, it is confirmed that when the additive content of the MgO-based agent is 10% in dry-mass basis, consumption of Mg is greatly suppressed by maintaining a pH in which the hydration reaction of MgO can occur sufficiently over the long term, and arsenic leaching concentrations are effectively decreased until the cumulative flow volume reaches 50 mL/g. However, in the cases of the agents containing a certain amount of calcium, the initial solubilization of Ca raises the pH to a level close to the isoelectric points of MgO, resulting in the lowered arsenic immobilization effect.

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