粉煤灰在高硫石煤提钒尾渣蒸压砖制备中的应用

Application of Fly Ash on Preparation of Stone Coal Vanadium Tailings Autoclaved Brick

石煤酸浸提钒尾渣是一种富含硫酸盐的硅铝材料,含硫高达16%。研究了以石煤酸浸提钒尾渣和熟石灰为主要原料制备蒸压砖,考察了添加粉煤灰对蒸压砖性能的影响,并采用XRD、DSC以及SEM形貌分析对其机理进行了探讨。结果表明:添加粉煤灰能很好的提高蒸压砖的抗压强度,添加量为25%时,砖坯强度达到GB11945-1999《蒸压灰砂砖》规定的MU15的要求;蒸压砖的主要矿物组成为CSH和钙矾石,以及部分托勃莫来石,硫酸盐以二水石膏的形式存在;粉煤灰在蒸压过程中提供活性的SiO2和Al2O3,在增加水化产物的同时促使二水石膏向钙矾石的转变,减少样品中的石膏含量,增加砖坯的稳定性。

Stone coal aciding vanadium tailings （AVT） is a kind of silicon aluminum materials, which contain abundant sulfate, reach to 16 percentages. Autoclaved bricks were prepared utilizing AVT and slaked lime, the influence of adding fly ash to the performance of the autoclaved brieks was studied, in addition, its mechanism was discussed by using XRD, DSC and SEM morphology analysis. The results show that adding fly ash could preferably enhance the compressive strength of autoclave brick, and the strength could well meet the demand of MU15 specified by the nation standard GB 11945-1999 《Autoclaved Lime-sand Brick》 when the addition reached 25%. CSH and tobermorite is the main mineral composition in autoclaved bricks, sulfate exists in the form of dehydrated gypsum; fly ash provide active SiO2 and A1203 in the autoclave process, which prompted dehydrate gypsum generate ettringite as well adding hydration products, reducing the sample concentration of gypsum, increasing the stability of the brick at the same time.