Element cycling and secondary mineralogy in porphyry copper tailings as a function of climate, primary mineralogy, and mineral processing

Determination of Elements Leachability from Sarcheshmeh Porphyry Copper Mine Tailings: Application of Toxicity Characteristic Leaching Procedure

“…Upward migration is later superimposed on the general trend of downward mobilization during the rainy season. These hydro-geochemical and environmental important processes are similar to those has been reported in previous studies (Dold and Fontboté 2001;Wu et al 2009;Zhao et al 2012). …”

“…In this climate regime, the water-flow direction changes to upward migration via the capillary force, and therefore, mobilized elements are transported to the top of the weathered tailings. This geochemical condition is same as the El Teniente and El Salvador porphyry copper tailings (Dold and Fontboté 2001).…”

“…Very high concentrations of Al (27,600 mg L −1 ), Cu (56,900 mg L −1 ), Mn (13,260 mg L −1 ), S (151,800 mg L −1 ), and Zn (3,935 mg L −1 ) were observed in the TCLP results of the evaporative samples (mean values are presented). Evaporation of tailings water, especially from weathering zone, commonly leads to super-saturation, which controls the precipitation of mainly water soluble secondary sulfate minerals (Johnson et al 2000;Dold and Fontboté 2001;McGregor and Blowes 2002). As suggested by other authors (e.g., Cravotta 1994;Lin 1997;Khorasanipour and Eslami 2014), formation and dissolution of secondary minerals, especially simple hydrous metal sulfates, can release metals, acidity, and sulfate into the water.…”

“…Tailing wastes become chemically unstable when exposed to an oxidizing environment, but the geochemical behavior of trace elements during the weathering and oxidation reactions, and subsequent acidic conditions, are considerably different. For example, the divalent cations are usually mobile under acidic conditions, while oxy-anions like Mo (V, VI) and As (V) show increasing adsorption to Fe (III) oxy-hydroxides with decreasing pH (Dzombak and Morel 1990;Dold and Fontboté 2001;Khorasanipour et al 2012). This relationship is reflected by the increased As concentration in Fe (III) oxy-hydroxides fraction in the oxidation zone of tailings (Dold and Fontboté 2001).…”

“…For example, the divalent cations are usually mobile under acidic conditions, while oxy-anions like Mo (V, VI) and As (V) show increasing adsorption to Fe (III) oxy-hydroxides with decreasing pH (Dzombak and Morel 1990;Dold and Fontboté 2001;Khorasanipour et al 2012). This relationship is reflected by the increased As concentration in Fe (III) oxy-hydroxides fraction in the oxidation zone of tailings (Dold and Fontboté 2001). Kelepertzis et al (2012) also noted that the low Pb level as 1-The natural adsorption by adsorptive agents such as Fe-oxy-hydroxides that retain trace elements such as As, Pb, Bi and Mo in the solid form; 2-The movement of the released trace elements (Ag, Al, Cr, Se and Sb) from weathering zone and concentrate in the surface evaporative layer.…”