复合硅酸盐水泥对含氟污泥的固化处理

Solidification treatment of fluorine-containing sludge by composite Portland cement

采用复合硅酸盐水泥对含氟污泥进行固化处理并制取了不同污泥掺量的水泥标准试块,考察了含氟污泥掺量对试块抗压强度、氟离子浸出量、物相转变和晶体形态的影响。结果表明,含氟污泥掺量(质量分数)为10%时,试块强度高,氟离子浸出量低。10%含氟污泥掺量试块28 d抗压强度达到22.2 MPa,满足一般垫层、基础、地坪及受力不大的结构强度要求;10%含氟污泥掺量试块在地下水和酸雨作用下的氟离子浸出量分别为0.16和0.39mg/L,远小于危险废物100mg/L的标准限值,安全性较高;机理研究表明,含氟污泥的加入加快了水泥中铝酸三钙(C_(3)A)的水化速度,增加了早期钙矾石(AFt)生成量,提高了试块早期强度。

Composite Portland cement was used to solidify fluorine-containing sludge and to prepare cement standard test blocks with different sludge content.The effects of fluorine-containing sludge content on the compressive strength,fluorine ion leaching amount,phase transformation and crystal morphology of test blocks were investigated.The results showed that when the fluorine-containing sludge content(mass fraction)was 10%,the prepared test block had the highest strength and low amount of fluorine ion leaching.The compressive strength of the test block after maintenance 28 d reached 22.2 MPa,which met the strength requirements of general cushion,foundation,floor and structure with little stress.The fluoride ion leaching amount of the test block with 10% fluorine-containing sludge under the action of groundwater and acid rain was 0.16 and 0.39 mg/L,respectively,far less than the standard limit of 100 mg/L of hazardous waste,indicating had high safety.Mechanism study indicated that the addition of fluorine-containing sludge accelerated the hydration rate of tricalciumaluminate(C_(3)A)in cement,increased the formation amount of ettringite(AFt)in the early stage,and improved the early strength of the test block.