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首页> 外文期刊>Environmental Science & Technology >Microstructural Analyses of Cr(VI) Speciation in Chromite Ore Processing Residue (COPR)
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Microstructural Analyses of Cr(VI) Speciation in Chromite Ore Processing Residue (COPR)

机译：铬铁矿加工残渣（COPR）中Cr（VI）形态的显微组织分析

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摘要

The speciation and distribution of Cr(VI) in the solid phase was investigated for two types of chromite ore processing residue (COPR) found at two deposition sites in the United States: gray-black (GB) granular and hard brown (HB) cemented COPR. COPR chemistry and mineralogy were investigated using micro-X-ray absorption spectroscopy and micro-X-ray diffraction, complemented by laboratory analyses. GB COPR contained 30% of its total Cr(VI) (6000 mg/kg) as large crystals (>20 μm diameter) of a previously unreported Na-rich analog of calcium aluminum chromate hydrates. These Cr(VI)-rich phases are thought to be vulnerable to reductive and pH treatments. More than 50% of the Cr(VI) was located within nodules, not easily accessible to dissolved reductants, and bound to Fe-rich hydrogamet, hydrotalcite, and possibly brucite. These phases are stable over a large pH range, thus harder to dissolve. Brownmillerite was also likely associated with physical entrapment of Cr(VI) in the interior of nodules. HB COPR contained no Cr(VI)-rich phases; all Cr(VI) was diffuse within the nodules and absent from the cementing matrix, with hydrogamet and hydrotalcite being the main Cr(VI) binding phases. Treatment of HB COPR is challenging in terms of dissolving the acidity-resistant, inaccessible Cr(VI) compounds; the same applies to ～50% of Cr(VI) in GB COPR.
机译：研究了在美国两个沉积地点发现的两种类型的铬铁矿矿石加工残留物（COPR）的固相中Cr（VI）的形态和分布：胶结的灰黑色（GB）和硬质棕色（HB） COPR。使用微X射线吸收光谱法和微X射线衍射技术对COPR化学和矿物学进行了研究，并辅以实验室分析。 GB COPR含有30％的总Cr（VI）（6000 mg / kg），是以前未报道的富含Na的铬酸铝钙水合物类似物的大晶体（直径大于20μm）。这些富Cr（VI）的相被认为易受还原和pH处理的影响。超过50％的Cr（VI）位于结核中，不易被溶解的还原剂接触，并与富铁的水配子，水滑石和可能的水镁石结合。这些相在较大的pH范围内是稳定的，因此很难溶解。褐煤还可能与结核内部的六价铬的物理截留有关。 HB COPR不包含富Cr（VI）相；所有Cr（VI）均弥散在结节内，而在胶结基质中不存在，其中水配子和水滑石是Cr（VI）的主要结合相。 HB COPR的治疗在溶解耐酸性，难以接近的Cr（VI）化合物方面具有挑战性。 GB COPR中约50％的Cr（VI）也是如此。

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  • 来源
    《Environmental Science & Technology》 |2009年第14期|5461-5466|共6页
  • 作者

    MARIA CHRYSOCHOOU; SIRINE C. FAKRA; MATTHEW A. MARCUS; DEOK HYUN MOON; DIMITRIS DERMATAS;

  • 作者单位

    Department of Civil and Environmental Engineering, University of Connecticut, Storrs, Connecticut 06269;

    Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, California;

    Department of Civil and Environmental Engineering, University of Connecticut, Storrs, Connecticut 06269;

    Stevens Institute of Technology, Hoboken, New Jersey;

    Stevens Institute of Technology, Hoboken, New Jersey;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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