铜渣基磷酸铁化学键合材料固化重金属Pb

铜渣堆积会造成资源浪费和环境污染等问题，利用铜渣与磷酸盐反应制备铜渣基磷酸铁化学键合材料(CBIPCs)，并用其固化重金属Pb。研究铜渣与磷酸二氢铵(m(CS)/m(P))配比、缓凝剂以及硝酸铅掺量对CBIPCs固化重金属Pb的影响。结果表明：随着硝酸铅掺量的增加，固化体抗压强度降低，Pb毒性浸出浓度略增大；在m(CS)/m(P)=3:1和硼砂掺量为2%的条件下，当硝酸铅掺量为12%，固化体自然养护28 d的抗压强度仍达到24.5 MPa，Pb毒性浸出浓度为0.086 mg·L-1，远低于《危险废物鉴别标准 浸出毒性鉴别》(GB 5085.3-2007) 要求的最高限值5.0 mg·L-1。XRD和SEM/EDS分析表明，固化体中生成了PbHPO4、Pb3(PO4)2、Pb5(PO4)OH等铅类磷酸盐产物，并被胶凝相物质紧密包裹。铜渣与磷酸盐反应制备的铜渣基磷酸铁化学键合材料(CBIPCs)，可通过化学键合和物理固封双重作用实现对重金属Pb的稳定固化。

Solidification of Pb using chemically bonded iron phosphate ceramics prepared with copper slag

Copper slag accumulation in dumps and landfills not only occupies large amount of lands, but also causes waste of resource and serious environment pollution. In this study, chemically bonded iron phosphate ceramics (CBIPCs) was prepared through the reaction between copper slag and acid phosphate to solidify the heavy metal Pb. The influences of the raw material ratios including the copper slag-to- acid phosphate mass ratio (CS/P), the borax dosage and the addition of lead nitrate on the properties of CBIPCs and the leaching characteristics of Pb were investigated. The results indicated that the compressive strength of solidified form decreased and the toxic leaching concentration of Pb slightly rose with the increase of lead nitrate addition. When the solidified form was prepared at the conditions: m(CS)/m(P) of 3.0, borax addition of 2.0% and lead nitrate addition amount of 12.0%, its compressive strength at 28 d natural curing could reach 24.5 MPa and the toxic leaching concentration of Pb was only 0.086 mg·L-1, which is far below the maximum limit of 5.0 mg·L-1 required by the Identification Standards for Hazardous Wastes Identification for Extraction Toxicity (GB 5085.3-2007). The analysis of XRD patterns and SEM/EDS images showed that insoluble lead phosphates, such as PbHPO4, Pb3(PO4)2, Pb5(PO4)OH were formed and encapsulated by CBIPCs. The immobilization of Pb with CBIPCs can be attributed to the chemical bond between phosphate and Pb and the physical encapsulation of heavy metal Pb.