Mineralogical and Geochemical Characteristics of the Precipitates in Acid Mine Drainage of the Heungjin-Taemaek Coal Mine

Abstract

Fe(II) released from mining activities is precipitated as various Fe(III)-oxyhydroxides when exposed to an oxidizing environment including mine drainage. Ferrihydrite, one of the representative precipitated Fe(III) minerals, is easy to adsorb heavy metals and other pollutants due to the large specific surface area caused by very low crystallinity. Ferrihydrite is transformed to thermodynamically more stable goethite in the natural environment. Hence, information on the transformation of ferrihydrite to goethite and the related mobility of heavy metals in the acid mine drainage is important to predict the behaviors of those elements during ferrihydrite to goethite transition. The behaviors of heavy metals during the transformation of ferrihydrite to goethite were investigated for core samples collected from an AMD treatment system in the Heungjin-Taemaek coal mine by using X-ray diffraction (XRD), chemical analysis, and statistical analysis. XRD results showed that ferrihydrite gradually transformed to goethite from the top to the bottom of the core samples. Chemical analysis showed that the relative concentration of As was significantly high in the core samples compared with that in the drainage, indicating that As was likely to be adsorbed strongly on or coprecipitated with iron oxyhydroxide. Correlation analysis also indicated that As can be easily removed from mine drainage during iron mineral precipitation due to its high affinity to Fe. The concentration ratio of As, Cd, Co, Ni, and Zn to Fe generally decreased with depth in the core samples, suggesting that mineral transformation can increase those concentrations in the drainage. In contrast, the concentration ratio of Cr to Fe increased with depth, which can be explained by the chemical bond of iron oxide and chromate, and surface charge of ferrihydrite and goethite.

Adsorption Characteristics of Oxyanions on Ferrihydrite and Mineral Phase Transformation

“…일 반적으로 페리하이드라이트는 침철석(goethite)과 적철석 (hematite)의 전구물질(precursor)로 알려져 있으며, 추후 이들 광물로 전이된다. 이와 관련하여 페리하이드라이트 의 상변화에 대해서 여러 연구들이 수행되었다 (Schwertmann and Murad, 1983;Zhao et al, 1994;Schwertmann et al, 1999;Schwertmann et al, 2004;Cudennec and Lecerf, 2006;Das et al, 2011a, Shin et al, 2021. 구체적으로, Schwertmann and Murad(1983) (Fuller et al, 1993;Martínez et al, 1999;Pedersen et al, 2006;Vu and Moreau, 2015).…”

Evaluation of Characteristics of Sludge generated from Active Treatment System of Mine Drainage

“…입도 분석방법은 습 식체분석으로 수행하였다. 입자크기는 침강속도의 주요 인자로 작용하여 수처리시 물리적으로 정화효율에 영향 을 끼치며 (Hwang et al, 2016), 흡착제 등으로 활용할 경 우 입자 크기에 따른 투수성 문제, 비표면적, 또는 비드 등으로 제작이 필요한지 등을 확인하는데 필요하다 (Zhao et al, 2011;Shin et al, 2021;Lee et al, 2021).…”