铬渣中六价铬滤出特性研究  

Leaching Characteristics of Cr(Ⅵ) from Chromite Ore Processing Residue

作　　者：肖凯[1] 李国成[1] 

机构地区：[1]华中科技大学土木工程与力学学院,湖北武汉430074

出　　处：《土木工程与管理学报》2013年第2期46-51,共6页Journal of Civil Engineering and Management

基　　金：国家自然科学基金(50808091)

摘　　要：六价铬从铬渣中滤出到土壤或地下水中,会对环境造成严重的污染。结合X射线衍射实验和扫描电子显微镜实验,通过批次实验评估颗粒尺寸,酸的种类和反应时间对六价铬滤出的影响。实验结果显示由于包括酸进入碱性固体内部、酸与碱性物质反应和最后碱性从固体内部释放的传输机理的影响,碱性物质在酸环境中从铬渣内部滤出是受到限制的。与硝酸相比,用硫酸更容易降低pH值并且使反应过程不容易产生氢氧化物沉淀,从而释放铬渣中的六价铬。扫描电镜显示相比于硫酸,铬渣在经过硝酸反应24 h后,其颗粒间缝隙处有较多铬元素,这说明铬元素从颗粒中滤出但可能吸附在颗粒缝隙中的氢氧化物沉淀上。所以硫酸更有利于铬渣中六价铬的滤出。但无论与那种酸反应,即使反应时间超过64 h仍然有大量的铬存在于铬渣之中,这说明了铬渣中铬的滤出有很强的持续性。另外,在本次实验中,粗颗粒很难与酸反应完全。相比于酸的种类而言,铬渣颗粒粒径大小更能影响六价铬的滤出。The leaching of Cr （VI） from chromite ore processing residue （COPR） into the soil or groundwater will result in serious environmental pollution. Complemented with X-ray diffraction （XRD） and environmental scanning electron microscopy （ESEM）, batch tests were conducted to evaluate the effects of particle size, acid type and mixing time on the leaching behavior of Cr（VI） from COPR. The test result indicated that alkaline material leached with acid was reported to be rate-limited by three mechanisms： H ~ penetration into the solid, subsequent reactions with alkaline minerals, and diffusion of OH - out of the solid. When H2SO4 was introduced, it was easier to lower the pH in leachate and more difficult to form precipitated metal oxyhydroxides relative to HNO3. It was benefit to the release of Cr（VI） from COPR treated with H2SO4. The result of ESEM shows that more Cr was found in the interstitial area of COPR treated with HNO3 for 24 h relative to H2SO4. That indicates Cr may be leached from COPR particle but absorbed to the surface of the precipitated metal oxyhydroxides in the interstitial area. So H2SO4 can be used as a more effective acid to make Cr（VI） leach from COPR. However, a large amount of Cr（VI） remained in COPR even after 64 h mixing time with HNO3 or HzSO4, which suggested the persistency of Cr（VI） leaching from COPR. In addition, it was difficult for coarse-sized particles in this study completely reacting with acid. Comparing with acid type used, the particle size may play a more important role in the release of Cr（VI） from COPR.

关 键 词：铬污染 铬渣 批次实验 酸处理 滤出行为 

分 类 号：X705[环境科学与工程—环境工程]