Leaching Mechanisms of Cr(VI) from Chromite Ore Processing Residue
Leaching Mechanisms of Cr(VI) from Chromite Ore Processing Residue
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DOI：
10.2134/jeq2007.0443
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发表时间：
2008-11-01
影响因子：
2.4
通讯作者：
Koutsospyros, Agamemnon
中科院分区：
文献类型：
--
作者：
Wazne, Mahmoud;Jagupilla, Santhi Chandra;Koutsospyros, Agamemnon
采用间歇浸出残留物、X射线粉末衍射(XRPD)定性定量分析和地球化学模拟等方法，研究了新泽西州哈德逊县市区铬铁矿选矿残渣(COPR)中铬(VI)的浸出机理。将浸出液的pH值调整到1到12.5的较大范围内。浸出液中总铬(Cr)和铬(VI)的浓度水平在pH值<；5时基本相同。在pH值<；5时，总铬的浓度超过了铬(VI)的浓度，两者之间的差异归因于铬(III)。地球化学模拟结果表明，在pH=10.5时，铬(VI)的溶解度受铬(VI)-水方解石和铬(VI)-钙矾石的控制，在pH<；8时，铬(VI)的溶解度受吸附控制。但实验结果表明，在pH=10.5时，铬(VI)的溶解度受铬(VI)-水解石和水滑石的部分控制。10、大多数含铬(Vl)矿物变得不稳定，它们的溶解导致浸出液中铬(VI)浓度的增加。在低pH(~lt；1.5)条件下，固相铬(III)和吸附铬(VI)的氧化物溶解并释放出铬(III)和铬(VI)。
Batch leaching rests, qualitative and quantitative x-ray powder diffraction (XRPD) analyses, and geochemical modeling were used to investigate the leaching mechanisms of Cr(VI) from chromite ore processing residue (COPR) samples obtained from an urban area in Hudson County, New,v Jersey. The pH of the leaching solutions was adjusted to cover a wide range between 1 and 12.5. Tie concentration levels for total chromium (Cr) and Cr(VI) in the leaching solutions were virtually identical for pH Values > 5. For pH values < 5, the concentration of total Cr exceeded that of Cr(VI) with the difference between the two attributed to Cr(III). Geochemical modeling results indicated that the solubility of Cr(VI) is controlled by Cr(VI)-hydrocalumite and Cr(VI)-ettringite at pH > 10.5 and by adsorption at pH < 8. However, experimental results suggested that Cr(VI) Solubility is controlled partially by Cr(VI)-hydrocalumite at pH > 10.5 and by hydrotalcites at pH > 8 in addition to adsorption of anionic chromate species onto inherently present metal oxides and hydroxides at pH < 8. As pH decreased to < 10, most of the Cr(Vl) bearing minerals become unstable and their dissolution contributes to the increase in Cr(VI) concentration in the lechate solution. At low pH ( < 1.5), Cr(III) solid phases and the oxides responsible for Cr(VI) adsorption dissolve and release Cr(III) and Cr(VI) into solution.