Treatment of mining acidic leachates with indigenous limestone, Zimapan Mexico

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• 作者：I. Labastida ; M.A. Armienta ; R.H. Lara-Castro ; A. Aguayo ; O. Cruz ; N. Ceniceros
• 关键词：Arsenic ; Limestone ; Acid mine leachates ; Passive treatment systems ; Hydrous ferric oxides
• 刊名：Journal of Hazardous Materials
• 出版年：15 November, 2013
• 年：2013
• 卷：262
• 期：Complete
• 页码：1187-1195
• 全文大小：1047 K

文摘

An experimental study to evaluate the potential of using indigenous limestones in a passive system to treat acid mine drainage, at a mining zone of Mexico was carried out. Chemical and mineralogical characteristics of four types of native rocks (KIT1, KIT2, KSS, QZ) showed distinct CaCO₃ contents. Synthetic aqueous leachates from an old tailings impoundment had a pH of 2.18, 34 mg/L As, 705 mg/L Fe_total, and 3975 mg/L SO₄^{2鈭?/sup>. To evaluate dissolution behavior of rocks, kinetic batch experiments with an acid Fe-rich solution were performed. Decaying kinetic constants adjusting H+ concentration to a first order exponential process were: KIT1 (k = 2.89), KIT2 (k = 0.89) and KSS (k = 0.47). Infrared spectrum and XRD of precipitates showed schwertmannite formation. To determine As and heavy metals (Fe, Cd, Zn, Al) removal from the synthetic leachates, batch experiments using KIT1 were developed. Arsenic decreased from 34.00 mg/L to 0.04 mg/L, Fe and Al were totally removed, and concentrations of Zn and Cd decreased 88% and 91% respectively. Analyses by IR and SEM-EDS indicate that co-precipitation with Fe-Hydroxides formed upon leachate interaction with limestone is the main As removal process. Chamosite, identified by XRD may participate in the removal of Al, SiO₂ and a fraction of Fe.}