利用焙烧铁尾矿制备透水砖的水化特征研究

Study on Hydration Characteristics of Permeable Brick Produced by Roasted Iron Tailings

利用铁尾矿制备透水砖是尾矿资源二次利用的重要途径之一,与普通铁尾矿相比,经焙烧后的铁尾矿可有效提高透水砖的强度。为查明焙烧铁尾矿提高透水砖性能指标的原因,在透水砖抗折强度和抗压强度分析的基础上,借助X射线衍射分析和扫描电子显微镜分析技术,系统研究了铁尾矿用量和养护时间对水化产物物相组成和微观结构的影响。结果表明:增加尾矿用量使透水砖强度降低,延长养护时间则使透水砖强度增加,焙烧铁尾矿用量60%、养护28 d时,透水砖的抗折强度和抗压强度分别为3.34 MPa和15.44 MPa。过量添加焙烧铁尾矿不利于水化反应的进行,导致水化产物的生成量减少,焙烧铁尾矿用量超过60%时尤为明显,而延长养护时间可促进水化反应的发生。水化产物呈现出3种微观形貌,即簇状结构、网状结构和针状结构,此3种形貌水化产物的形成使砖体结构变得密实,从而提高了透水砖的强度。研究结果对采用焙烧铁尾矿制备高性能透水砖有一定的指导意义。

The preparation of permeable brick by iron tailings is one of the important ways of secondary utilization of tailings resources.Comparing with ordinary iron tailings,the roasted tailings can improve the strength of permeable brick ef⁃fectively.To find out the reasons that roasted iron tailings improve the performance index of permeable brick,the rupture strength and compressive strength of permeable bricks were analyzed,while the effects of iron tailings dosage and curing time on phase composition and microstructure of hydration products were investigated by X-ray diffraction and scanning elec⁃tron microscope analysis methods.The results showed that the strength of permeable brick decreased with increasing the dos⁃age of roasted iron tailings but increased with extending curing time.The rupture strength and compressive strength of perme⁃able brick reached 3.34 MPa and 15.44 MPa under the conditions of 60%dosage of roasted iron tailings and 28 d curing time,respectively.Over-dosed tailings was harmful to hydration reaction and resulted in a reduction of hydration products,which was more obvious at the dosage of roasted iron tailings above 60%.However,extending the curing time was favorable for fully developed of hydration reaction.The hydration products present three kinds of microscopic appearance,namely:cluster tree,net structure,and acicular structure,which compacted the structure of permeable brick and improved its strength.The investigated results proved a guiding significance for the preparation of high-performance permeable brick by calcined iron tailings.