金瓜石黃金瀑布酸性礦山排水沉澱物之礦物學研究

A Mineralogical Study of Acid Mine Drainage Precipitates from Golden Falls, Chinkuashih

陳君榮(Chun-Jung Chen) ； 江威德(Wei-The Jiang)

《臺灣鑛業》 65卷3期 (2013/09) Pp. 1-12

摘要

金瓜石金銅礦床及廢礦石經化學風化作用，長年排放酸性礦山排水，在黃金瀑布河床表層形成黃褐色氫氧氧化纖沉澱物，該沉澱物之X光繞射、紅外線光譜、電子顯微鏡和熱重／熱差分析顯示其主要礦物組成為schwertmannite（四方硫酸纖鐵礦），生成纖維狀奈米晶束，放射狀排列聚集形成直徑大多為數微米之準圓球狀集合體，集合體表面具刺蝟狀形貌，比表面積達76m^2/g。感應藕合電漿分析顯示此schwertmannite之平均化學式為Fe16O16(OH)11(S04)2.5．16H2O，並含有2,794 ppm坤、439 ppm鋁、115 ppm 銅及23 ppm鉻。Schwertmannite沉澱及其對砷和金屬之吸附作用有助於延緩或降低黃金瀑布酸性礦山排水對環境污染之影響。

關鍵字

酸性礦山排水 ； 四方硫酸纖鐵礦 ； 砷 ； 金瓜石

並列摘要

Ochreous iron-oxyhydroxide precipitates occur at the bedrock surface of Golden Falls as a result of the long-term discharge of acid mine drainage (AMD) produced by chemical weathering of the Chinkuashih gold-copper deposits and tailings. X-ray diffraction, SEM, TEM, FTIR, ICP, and TG-DTA data indicated that the ocher precipiates were dominated by schwertmannite with an average chemical formula of Fe16O16(OH)11(S04)2.5．16H2O. The schwertmannite occurred as nanometric fibrous crystallites that had an radiating arrangement forming spheroidal aggregates with hedgehog-like surface microstructures and a specific surface area of 76 m^2/g. The ICP analysis further suggested that the schwertmannite contained 2,794 ppm As, 439 ppm Al, 115 ppm Cu, and 23 ppm Cr on average. The result implies that the environmental impacts of the Golden Falls AMD may have been deferred and/or reduced by the precipitation of schwertmannite and the sorption of As and metals thereon.

並列關鍵字

acid mine drainage ； schwertmannite ； arsenic ； Chinkuashih