Matern Katrin, Kletti Holger, Mansfeldt Tim
Soil Geography/Soil Science, Department of Geosciences, University of Cologne, Albertus-Magnus-Platz, 50923 Cologne, Germany.
F.A. Finger-Institut für Baustoffkunde, Bauhaus-Universität Weimar, Coudraystraße 11, 99421 Weimar, Germany.
Chemosphere. 2016 Jul;155:188-195. doi: 10.1016/j.chemosphere.2016.04.009. Epub 2016 Apr 22.
Chromite ore processing residue (COPR) is a hazardous waste. Nevertheless, deposition of COPR in uncontrolled surface landfills is still common practice in some countries. Whereas old (between at least 40 and 180 years) COPR from the temperate zone has been intensively investigated, information on COPR in other regions is restricted. Relatively young (<25 years) COPR samples obtained from two abandoned landfill sites in India were investigated by a modified total microwave digestion method, X-ray powder diffraction (XRPD), and scanning electron microscopy (SEM) in order to determine their chemical and mineralogical nature. By the use of microwave digestion with acid mixtures of HNO3, H3PO4, and HBF4 (5:3:2 vol), COPR was completely dissolved and element contents similar to those obtained by X-ray fluorescence were found. Total Cr contents of the two COPR accounted for 81 and 74 g kg(-1), of which 20 and 13% were present in the carcinogenic hexavalent form (CrVI). Apart from the common major mineral phases present in COPR reported earlier, a further Cr host mineral, grimaldiite [CrO(OH)], could be identified by XRPD and SEM. Additionally, well soluble Na2CrO4 was present. Improving the effectiveness of chromite ore processing and preventing the migration of Cr(VI) into water bodies are the main challenges when dealing with these COPR.
铬铁矿加工残渣（COPR）是一种危险废物。然而，在一些国家，将COPR随意倾倒在露天垃圾填埋场仍是常见做法。尽管对温带地区至少有40至180年历史的旧COPR进行了深入研究，但关于其他地区COPR的信息却很有限。为了确定来自印度两个废弃垃圾填埋场的相对年轻（<25年）的COPR样品的化学和矿物学性质，采用改进的全微波消解方法、X射线粉末衍射（XRPD）和扫描电子显微镜（SEM）对其进行了研究。通过使用HNO3、H3PO4和HBF4（体积比5:3:2）的混合酸进行微波消解，COPR完全溶解，且发现其元素含量与X射线荧光法测得的结果相似。两种COPR的总铬含量分别为81和74 g kg⁻¹，其中20%和13%以致癌的六价形式（CrVI）存在。除了之前报道的COPR中常见的主要矿物相外，通过XRPD和SEM还鉴定出了另一种含铬矿物——斜方铬铁矿[CrO(OH)]。此外，还存在易溶的Na2CrO4。提高铬铁矿加工效率并防止Cr(VI)迁移到水体中是处理这些COPR时面临的主要挑战。
