固硫灰固化焦化废水处理外排污泥

Solidification of coking wastewater sludge with CFBC ashes

采用机械力化学法活化循环流化床燃煤固硫灰,用于固化焦化废水处理外排污泥(CWT污泥)。探讨了固硫灰活化条件,并通过XRD和FTIR分析了固硫灰固化CWT污泥中重金属的机理。实验结果表明:当m(Ca O)∶m(Ca O+固硫灰)为20%、球磨频率为40 Hz、球磨时间为2 h时,养护28 d固硫灰固化体的平均抗压强度达到72.2 MPa;当污泥掺加量为50%(w)时,养护28 d含污泥固化体的抗压强度达到8.5 MPa,固化体浸出液中Pb2+和As5+的质量浓度分别为0.177 mg/L和0.013 mg/L,均远低于GB 5085.3—2007《危险废物鉴别标准浸出毒性鉴别》的规定限值。XRD和FTIR表征结果表明,在固硫灰活化过程中,混合体系水化生成了C—S—H凝胶、斜方钙沸石和钙矾石,可通过物理包裹、吸附及离子交换的形式实现CWT污泥中Pb2+和As5+的固化/稳定化。

The circulating fluidized bed combustion （CFBC） ashes was activated by mechanochemical method and used for solidification of sludge in coking wastewater treatment （CWT sludge）. The optimum conditions for activation of CFBC ashes were discussed and the immobilization mechanism of heavy metals in CWT sludge was analyzed. The experimental results show that： When m （CaO） ： m （CaO＋CFBC ash） is 20%, the milling frequency is 40 Hz and the milling time is 2 h, the average compressive strength of the CFBC ash solidified body after 28 d of curing is 72,2 MPa; When the dosage of CWT sludge is 50% （w）, the compressive strength of the CFBC ash-CWT sludge solidified body after 28 d of curing is 8.5 MPa, and the mass concentration of Pb2＋ and As5＋ in the solidified body leaching liquid are 0.177 mg/L and 0.013 mg/L respectively, which are much lower than the national standard value of GB 5085.3-2007. The characterization results show that during the CFBC ash activation process, C--S--H gel, gismondine and ettringite are generated by hydmtation, with which Pb2＋ and As5＋ in CWT sludge can be solidified/stabilized by forms of physically encapsulated, adsorption and ion-exchange.