Speciation of arsenic in an anaerobic treatment system at a Pb-Zn smelter site, gold roaster products, Cu smelter stack dust and impacted soil
- CCM
Mining and metallurgical processing of gold and base metal ores often results in solid wastes and effluents containing high concentrations of arsenic. In addition, arsenic can be released to the atmosphere from gold roasters and base metal smelters. Speciation of arsenic in roaster products, in a stack sample from a copper smelter, in organic soils impacted by smelter emissions, and in an anaerobic effluent treatment system at a smelter site was determined in order to broaden our understanding of the nature and occurrence of arsenic in a wider range of metallurgical wastes. Micro-XANES spectra obtained from iron oxide particles forming in a gold roaster indicate preferential enrichment of As{sup 3+} species in maghemite-rich domains and microlayers. In comparison, haematite-rich iron oxide particles are dominated by As{sup 5+} species. It appears that maghemite is retarding oxidation of arsenic and its volatilisation during roasting. Arsenic occurs as both As{sup 3+} and As{sup 5+} species in a stack sample emitted from a Cu smelter, confined to fine-grained secondary product layers accumulated on the surfaces of spherical Cu particles. This is probably resulting from condensation of As species upon cooling following their volatilisation during the combustion process. Soil samples collected at various distances from the Cu smelter are dominated by As{sup 5+} species including monomethylarsonic acid and tetramethylarsonium iodide as the organic arsenic species. The presence of reduced As{sup 3+} species highlights the importance of organic material influencing the speciation of arsenic and mineralogical transformations taking place within the soil profile. The XANES spectra indicate that arsenic occurs predominantly as aqueous arsenite species in the anaerobic treatment system, contrary to the conventional thinking of As retention by the formation of secondary sulfides.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1009050
- Resource Relation:
- Conference: Ninth International Congress for Applied Mineralogy ICAM2008;8-10 Sep 2008;Brisbane, Australia
- Country of Publication:
- United States
- Language:
- ENGLISH
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