Mineralogy and geochemistry of sulfide-bearing tailings from silver mines in the Taxco, Mexico area to evaluate their potential environmental impact environmental impact
Six sulfide-bearing, flotation tailings dams and one waste-rock dump from epithermal Pb-Zn-Ag-Cu deposits in Taxco,Guerrero have been mineralogically and geochemically characterized to evaluate their potential environmental impact. Primaryphases are dominated by quartz and rock fragments with scarce...
| Autores: | , , , , , |
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| Tipo de documento: | artigo |
| Estado: | Versão publicada |
| Data de publicação: | 2005 |
| País: | México |
| Recursos: | Universidad de Sonora |
| Repositório: | Redalyc-USON |
| OAI Identifier: | oai:redalyc.org:56844105 |
| Acesso em linha: | https://www.redalyc.org/articulo.oa?id=56844105 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Ciencias de la Tierra Taxco sulfide tailings toxicity heavy metals |
| Resumo: | Six sulfide-bearing, flotation tailings dams and one waste-rock dump from epithermal Pb-Zn-Ag-Cu deposits in Taxco,Guerrero have been mineralogically and geochemically characterized to evaluate their potential environmental impact. Primaryphases are dominated by quartz and rock fragments with scarce feldspar, barite and ferromagnesian. Calcite is found in the lessoxidized tailings. Primary sulfides are pyrite and sphalerite with some pyrrothite, galena, chalcopyrite, Ag-sulfosalts and arsenopyrite.In oxidized zones, sulfides are low or absent. Secondary phases are widespread and include gypsum, chalcocite, keoheite,nimite, hetaerolite, jarosite, smithsonite, bernalite, epsonite, rozenite, pickeringite, hexahydrite, bassanite, boyleite, hematite,scorodite, cryptocrystalline and amorphous precipitates and poorly crystallized Fe-oxyhydroxides. EDS analysis suggests thatadsorption is important in the retention of metals.All Taxco tailings and waste-rock dumps show high concentrations of total Ag (9.5 74.2 mg/kg), Cd (1.0-780 mg/kg), Cu(71.8-1320 mg/kg), Fe (2.49-25.1%), Mn (18.6-13 800 mg/kg), Pb (780-43 700 mg/kg), V (2.0-127 mg/kg), Zn (380->10 000 mg/kg) and As (19.0-11 800 mg/kg) exceeding the regional background concentrations in crop soils. Contents of water-soluble metalsare heterogeneous but contain significant amounts of toxic metals (e.g. Cd = <0.005-19.2 mg/L; Cu = <0.025-63 mg/L; Fe =>0.025-1105 mg/L; Pb = <0.025-0.655 mg/L; As = <0.010-1.79 mg/L), particularly from highly oxidized zones. The release isprimarily controlled by pH. Sulfide oxidation and generation of AMD are coupled by dissolution, neutralization via calcite,reprecipitation and adsorption. |
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