Metal mobilization in tailings originated from the mining district of Guanajuato, Mexico

Characterization of different tailings from the mining district of Guanajuato. Mexico were carried out, including a tailing from an abandoned dam 20 years ago, a dam in operation and another coming from the mixture of different companies. The three tailings presented alkaline conditions, normal salinity, aerobic environment with oxidative tendency, low humidity, very low capacity of cationic exchange, and absence of organic matter. These conditions restrict the metal mobility. The mineralogical analysis showed that the tailings contained mainly quartz, calcite and magnetite. Tailings coming from the mixture of different companies had greater total concentrations (mg kg) of Mn (1042.8). Al (12919.8), Fe (23911.3), Cr (71.3), Pb (24.6) and Cu (19.8). The highest concentration of Zn was observed at the abandoned tailing (53.3 mg/kg). No significant concentrations of Cd and Hg were observed, although Pb (24.6 mg/kg) and Cr (71.4 mg/kg) were detected. Leaching tests indicated that metals cannot be leached in percentages higher than 0.1%, and so these tailings do not represent an environmental risk. The low leaching of metals in the studied tailings was consistent with the mineralogical and physicochemical prevailing conditions, the low acid drainage generation potential and the high degree of stability observed in the tests of metals fractionation.Original Abstract: Se realizo la caracterizacion de tres jales del distrito ininero de Guanajuato: uno abandonado hace 20 anos (Presa Abandonada), uno reciente (Presa en Opcracion) y un jal proveniente de la mezcla de diferentes companias (Presa Mezcla). Los tres jales presentaron caracter alcalino, condiciones aerobias con tendencias oxidantes, bajo contenido de humedad, muy baja capacidad de intercambio cationico y ausencia de materia organica. Estas condiciones limitan la lixiviacion de metales. Los analisis mineralogicos mostraron que los jales estan constituidos mayoritariamente por cuarzo, calcita y magnetita. Los jales provenientes de la Presa Mezela presentaron las mayores concentraciones totales (mg/kg) de Mn (1042.8), Al (12919.8), Fe (23911.3), Cr (71.3), Pb (24.6) y Cu (19.8). El Zn se encontro en mayor concentracion en los jales de la Presa Abandonada (53.3 mg/kg). No se observaron concentraciones significativas de Cd y Hg, pero se detecto Pb (24.6 mg/kg) y Cr (71.4 mg/kg). Las prucbas de lixiviacion indicaron que ninguno de los metales lixivio en porcentajes mayores al 0.1 %. En consecuencia, los jales e