氟、磷与重金属离子共掺对C_(3)S烧成及水化进程的协同影响机理

Synergistic Influence Mechanism of Fluorine,Phosphate and Heavy Metal Ions Co-Doping on Formation and Hydration of Tricalcium Silicate

含氟污泥作为半导体行业精细化生产的主要副产品,是一种危险固废。在水泥窑协同处置含氟污泥的过程中,含氟污泥中含有的氟、磷和多种重金属离子会不可避免地引入到水泥生料中,这些离子会显著影响并改变水泥生料矿物的煅烧过程及其性能,然而它们共存时对水泥熟料性能的影响研究尚不多见,为此,本文系统研究了氟、磷与重金属离子共掺对硅酸三钙(C_(3)S)煅烧过程、微观结构以及水化特性的协同影响机理。研究表明,与磷酸盐单掺相比,磷和重金属离子复掺不利于C_(3)S烧成,而氟、磷与重金属离子共掺对C_(3)S的烧成有显著的协同促进作用,同时明显提高了C_(3)S晶型对称性,使C_(3)S矿物表面出现更多不同种类的缺陷。与磷酸盐单掺相比,磷和重金属离子复掺有利于提高C_(3)S初始和后期水化速率,降低棒状水化硅酸钙(C-S-H)的长径比,而氟、磷和重金属离子共掺对C_(3)S水化性能的影响取决于各离子的掺比,但随着各离子掺量的增加,C_(3)S水化加速期却会不断推迟,且三者共掺会促进棒状C-S-H长径比增加。

Fluorinated sludge,as the main byproduct of refined production in the semiconductor industry,is a hazardous solid waste.In the process of co-treating fluorine-containing sludge in cement kilns,the fluorine,phosphate,and various heavy metal ions contained in the fluorinated sludge will inevitably be introduced into the cement raw material at the same time.These ions will significantly affect and change the calcination process and properties of cement raw material minerals.However,there are few studies on the impact of their coexistence on the properties of cement clinker.Therefore,this paper systematically studied the synergistic influence mechanism of fluorine,phosphate,and heavy metal ions co-doping on the calcination process,microstructure,and hydration characteristics of tricalcium silicate(C_(3)S).The results show that compared with the single doping of phosphorus,the co-doping of phosphate and heavy metal ions is not conducive to the firing of C_(3)S,while the co-doping of fluorine,phosphate,and heavy metal ions has a significant synergistic promoting effect on the firing of C_(3)S,while significantly improving the symmetry of C_(3)S crystal structure,resulting in more defects of different types on the surface of C_(3)S minerals.Compared with the single doping of phosphorus,the co-doping of phosphate and heavy metal ions is beneficial for improving the initial and later hydration rates of C_(3)S,reducing the aspect ratio of rod-shaped hydrated calcium silicate(C-S-H).The effect of co-doping of fluorine,phosphate,and heavy metal ions on the hydration performance of C_(3)S depends on the doping ratio of each ion.However,as the doping amount of each ion increases,the acceleration period of C_(3)S hydration will be continuously delayed,and the co-doping of the three ions will promote the increase of the aspect ratio of rod-shaped C-S-H.