skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Application of Synchrotron-based Micro-analysis to Mine Waste Miineralogy

Abstract

No abstract prepared.

Authors:
; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930575
Report Number(s):
BNL-80782-2008-JA
Journal ID: ISSN 0016-7037; GCACAK; TRN: US200904%%598
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Geochimica et Cosmochimica Acta; Journal Volume: 70; Journal Issue: 18
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 58 GEOSCIENCES; MINERAL WASTES; MINERALOGY; MICROANALYSIS; SYNCHROTRON RADIATION; national synchrotron light source

Citation Formats

Jamieson,H., Walker, S., and Andrade, C. Application of Synchrotron-based Micro-analysis to Mine Waste Miineralogy. United States: N. p., 2006. Web. doi:10.1016/j.gca.2006.06.586.
Jamieson,H., Walker, S., & Andrade, C. Application of Synchrotron-based Micro-analysis to Mine Waste Miineralogy. United States. doi:10.1016/j.gca.2006.06.586.
Jamieson,H., Walker, S., and Andrade, C. Sun . "Application of Synchrotron-based Micro-analysis to Mine Waste Miineralogy". United States. doi:10.1016/j.gca.2006.06.586.
@article{osti_930575,
title = {Application of Synchrotron-based Micro-analysis to Mine Waste Miineralogy},
author = {Jamieson,H. and Walker, S. and Andrade, C.},
abstractNote = {No abstract prepared.},
doi = {10.1016/j.gca.2006.06.586},
journal = {Geochimica et Cosmochimica Acta},
number = 18,
volume = 70,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • Understanding the solid-phase speciation of arsenic in soils and sediments is important in evaluations of the potential mobility of arsenic and of its bio-availability in the environment. This is especially true in mine-influenced environments, where arsenic commonly is present at concentrations two and three orders of magnitude above quality criteria for soils and sediments. Arsenic-bearing particulates dispersed through hydraulic transport or aerosol emissions can represent a persistent source of contamination in sediments and soils adjacent to past mining and metallurgical operations. The stability and mobility of arsenic associated with these phases depend on the chemical form and oxidation state ofmore » the arsenic and the interaction with post-depositional geochemical conditions. The Giant mine in Yellowknife, Northwest Territories, roasted arsenic-bearing gold ore from 1949 to 1999. The roasting process decomposed arsenic-bearing sulfides (pyrite and arsenopyrite) to produce a calcine containing fine (generally <50 {micro}m) arsenic-bearing iron oxides. We have applied synchrotron As K-edge micro X-ray Absorption Near-Edge Structure ({micro}XANES) and {micro}XRD as part of a grain-by-grain mineralogical approach for the direct determination of the host mineralogy and oxidation state of As in these roaster-derived iron oxides. The grain-scale approach has resolved potential ambiguities that would have existed had only bulk XANES and XRD methods been applied. Using combined optical microscopy, electron microprobe and {micro}XRD, we have determined that the roaster-iron oxides are nanocrystalline grains of maghemite containing <0.5 to 7 wt.% As. Some of these arsenic-bearing nanocrystalline grains are a mixture of maghemite and hematite. All roaster iron oxides, including those present in 50-year-old tailings, contain mixtures of As{sup 5+} and As{sup 3+}. The persistence of As{sup 3+} in roaster-derived maghemite in shallow subareal (oxidized) shoreline tailings for over 50 years suggests that the arsenic is relatively stable under these conditions, even though As{sup 3+} is a reduced form of arsenic, and maghemite is normally considered a metastable phase.« less
  • X-ray Absorption Near Edge Spectroscopy (XANES) gives arsenic form directly in the solid phase and has lower detection limits than extraction techniques. An important and common application of XANES is to use the shift of the edge position to determine the valence state. XANES speciation analysis is based on fitting linear combinations of known spectra from model compounds to determine the ratios of valence states and/or phases present. As(V)/As(III) ratios were determined for various Australian mine waste samples and dispersed mine waste samples from river/creek sediments in Vatukoula, Fiji.
  • The analysis of cultural Heritage objects is often technically challenging. When analyzing micro-fragments, the amount of matter is usually very tiny, hence requiring sensitive techniques. These samples, in particular painting fragments, may present multi-layered structures, with layer thickness of {approx}10 {mu}m. It leads to favor micro-imaging techniques, with a good lateral resolution (about one micrometer), that manage the discriminative study of each layer. Besides, samples are usually very complex in term of chemistry, as they are made of mineral and organic matters, amorphous and crystallized phases, major and minor elements. Accordingly, a multi-modal approach is generally essential to solve themore » chemical complexity of such hybrid materials. Different examples will be given, to illustrate the various possibilities of synchrotron-based micro-imaging techniques, such as micro X-ray diffraction, micro X-ray fluorescence, micro X-ray absorption spectroscopy and micro FTIR spectroscopy. Focus will be made on paintings, but the whole range of museum objects (going from soft matter like paper or wood to hard matter like metal and glass) will be also considered.« less
  • Biocompatible materials such as titanium are regularly applied in oral surgery. Titanium-based implants for the replacement of missing teeth demand a high mechanical precision in order to minimize micro-bacterial leakage, especially when two-piece concepts are used. Synchrotron-based hard x-ray radiography, unlike conventional laboratory radiography, allows high spatial resolution in combination with high contrast even when micro-sized features in such highly attenuating objects are visualized. Therefore, micro-gap formation at interfaces in two-piece dental implants with the sample under different mechanical loads can be studied. We show the existence of micro-gaps in implants with conical connections and study the mechanical behavior ofmore » the mating zone of conical implants during loading. The micro-gap is a potential source of implant failure, i.e., bacterial leakage, which can be a stimulus for an inflammatory process.« less