Vitrification of Chromium Electroplating Sludge

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• 作者：Chun-Teh Li ; Wen-Jhy Lee ; Kuo-Lin Huang ; Sheng-Feng Fu ; Yi-Chieh Lai
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：April 15, 2007
• 年：2007
• 卷：41
• 期：8
• 页码：2950 - 2956
• 全文大小：336K
• 年卷期：v.41,no.8(April 15, 2007)
• ISSN：1520-5851

文摘

This work investigated the vitrification of hazardouselectroplating sludge containing 140 mg/g Cr with/withoutbottom ash or cullet conditioning to lower specimens'basicities to 0.97-1.17 or 0.18-0.23, respectively. Theconditioning was found to enhance the smooth/glassyappearance of slags but no ingot was obtained. Cr was>98% retained in the vitrified slags. Cr₂O₃ dominated incrystalline structure for the slag vitrified from the sludge, butthis domination gradually shifted to Fe₂SiO₄/Fe₃O₄/SiO₂ orSiO₂ crystalline with increasing addition of bottom ash orcullet into the sludge, respectively. Compared to the rawsludge, the sludge-vitrified slag displayed lower leachingconcentrations for most metals (particularly Cr (2.54 mg/L)), and smaller leaching ratios for Ag, Cr, and Cu (1.35, 0.02,and <0.01%, respectively) but greater ones for Cd, Pb,and Zn (3.83, 2.46, and 0.36%, respectively). The Cr leachingratios were ~0.01% for the slags vitrified from theconditioned sludge. Independent of the slag basicity andcrystalline structure, metal leaching quantity increased butleaching ratio decreased with increasing slag metalcontent. The slag compressive strengths were improvedto >14.7 MPa at the mixing ratios 2/1 and 1/1 for bottomash/sludge and cullet/sludge, respectively. Fulfilling thecriteria of Toxicity Characteristic Leaching Procedure (TCLP),all the slags were recyclable.