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利用富含铁氧化物的铜渣和磷酸二氢钾反应制备铁系磷酸盐化学键合材料,并将其作为基体材料固化重金属离子Pb~(2+)。研究了原料配比、缓凝剂及硝酸铅掺量对胶凝材料初凝时间和抗压强度的影响。结果表明,当m(P)/m(CS)为1/4及硼砂掺量为2%时,材料性能最好,自然养护28d和常压蒸汽养护24h抗压强度分别可达44.78 MPa和30.48 MPa。随着重金属铅掺量的增加,固化体抗压强度逐渐降低,铝掺量为4.5%时,自然养护28d和蒸汽养护24h固化块抗压强度均大于10 MPa。对固化体的重金属毒性浸出试验表明:铁系磷酸盐化学键合材料对重金属离子Pb~(2+)具有很好的固化效果,固化体毒性浸出质量浓度远低于国家浸出毒性鉴别标准限值(5mg/L)。通过XRD、SEM和FTIR对重金属固化体进行表征分析,发现固化体中形成了PbHPO_4和Pb_3(PO_4)_2等重金属磷酸盐产物,并被铁系磷酸盐胶凝相物质紧密包裹,从而通过化学键合和物理包裹等双重作用实现重金属Pb的稳定固化。
The iron phosphate chemical bonding material is prepared by the reaction of copper slag and potassium dihydrogen phosphate which are rich in iron oxide and used as a base material to solidify heavy metal ions Pb2 +. The effect of raw material ratio, retarder and lead nitrate content on initial setting time and compressive strength of cementitious materials was studied. The results show that when the m (P) / m (CS) is 1/4 and the content of borax is 2%, the material properties are the best. The compressive strength of natural curing for 28 days and atmospheric curing for 24h are respectively 44.78 MPa and 30.48 MPa. With the increase of the content of heavy metal lead, the compressive strength of cured body decreased gradually. When the content of aluminum was 4.5%, the compressive strength of cured block after natural curing for 28 days and steam curing for 24h were more than 10 MPa. The results of heavy metal toxicity leaching test showed that the iron phosphate chemical bonding material has a good curing effect on heavy metal ions Pb2 +, and the solidified toxic leaching mass concentration is much lower than the national standard of identification of leaching toxicity ( 5 mg / L). The results of XRD, SEM and FTIR indicate that the heavy metal products such as PbHPO4 and Pb3 (PO4) 2 are formed in the solidified body and are tightly encapsulated by the iron phosphate gelled phase, And the dual role of physical package to achieve the stable solidification of heavy metals Pb.