垃圾焚烧飞灰制作碱激发砖的环境安全性评估

Environmental safety assessment of alkali-activated bricks produced by waste incineration fly ash

为探索垃圾焚烧飞灰的资源化利用,使用流化床焚烧炉产出的焚烧飞灰、燃煤飞灰及矿渣粉为主要原料,由氢氧化钠及硅酸钠调制为碱激发剂制备碱激发砖材.当焚烧飞灰最大添加比为40%时,其28 d的抗压强度达28.69 MPa,符合混凝土实心砖规范(GB/T21144—2007)要求.环境兼容性方面,28 d的垃圾焚烧飞灰碱激发砖材HJ/T 300浸出测试结果显示,重金属稳定于砖材中.长期pH相关联性浸出试验发现,砖材中重金属Ba的浸出量随pH的降低而增加;重金属Zn在pH小于7的环境下可检测到有浸出,而重金属Cd、Cr、Cu、Ni、Pb只有在pH为6以下的环境才会有浸出现象.桶槽扩散浸出试验结果显示,焚烧飞灰碱激发砖材环境稳定pH在11.0~11.5,且仅有微量重金属钡(Ba)及铬(Cr)出现释出现象,分析显示其浸出量为微量.

To explore the resource utilization of waste incineration fly ash,the incineration fly ash,coal-fired fly ash,and slag powder produced by fluidized bed incinerator were selected as main raw materials,and alkali-activated bricks were prepared by using sodium hydroxide and sodium silicate as alkali activators.When the ratio of the maximum addition of incineration fly ash was 40%,the 28-day compressive strength reached 28.69 MPa,which meets the requirements of GB/T21144—2007 concrete solid bricks.In terms of environmental compatibility,the HJ/T 300 test on the 28-day alkali-activated brick produced by waste incineration fly ash shows that heavy metals were stable in the brick.Long-term pH-related leaching test reveals that the leaching amount of heavy metal Ba in the brick increased with the decrease of pH value;leaching of heavy metal Zn could be detected in the environment with pH value less than 7,and heavy metals Cd,Cr,Cu,Ni,and Pb only appeared in the environment below pH 6.Results of tank and sink diffusion dissolution test show that the alkali-activated bricks produced by incineration fly ash had an environmentally stable pH value between 11.0 and 11.5 that only heavy metals Ba and Cr appeared,and analysis shows that the leaching amount was trace.