Abstract's Details

Speciation of Metal-Bearing Mine Wastes Using Micro X-ray Fluorescence
Abstract ID	ENV-05
Presenter	Stefanie Miller
Presentation Type	Poster
Full Author List	S. R. Miller (1), K. Wilson (1), E. Sugihara (1), C. S. Kim (1)
Affiliations	(1) Chapman University
Category	Environmental Science
Abstract	The mining industry generates hazardous metal-bearing wastes that can adversely affect human health. It is important to understand the distribution and speciation of metals in the environment as a function of particle size, as both relate to variances in hazard level. Using micro X-ray fluorescence (mXRF), metal-specific maps of particles can be generated to study associations between metals. Mine wastes from Randsburg, California were collected, separated by particle size into eleven distinct size fractions (labeled S1-S11), and analyzed at SSRL on beamline 2-3 using mXRF to identify various forms of arsenic present in samples. The particle size ranges analyzed in each sample included S5 (250-500um), S7 (75-125mm), S9 (32-45mm), and S11 (<20mm). Using the software program Microtoolkit, correlation plots between pairs of different metals were generated, allowing the identification of different populations of particles according to particle size. Strong correlations between arsenic and iron were often found, exhibiting differences between samples of mine tailings and samples of background material. Generally, a greater diversity of Fe-associated As particles was found in tailings samples than in background samples, as well as with decreasing particle size. This diversity in tailings samples is probably due to the introduction of new species as a result of ore processing. In smaller size fractions, the wider range of As species may be due to weathering and/or secondary mineral formation.
Footnotes
Funding Acknowledgement	Portions of this research were carried out at the Stanford Synchrotron Radiation Laboratory, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. This study was supported by a grant from the USGS-Mineral Resources External Research Program, and beamtime was provided through SSRL beamtime proposal #3113.