污泥和高炉渣协同制备微晶玻璃

利用污泥焚烧灰渣含有大量的氧化硅以及一定量重金属和磷的组成特点,将其作为成分调整剂、晶核剂及助熔剂,在未添加任何化学制剂的条件下与冶金高炉渣协同制备了具有良好的力学性能和化学稳定性的污泥–高炉渣微晶玻璃.利用差热分析、X射线衍射、扫描电镜等分析手段,并结合力学性能和化学稳定性能测试,研究了不同热处理制度对微晶玻璃性能的影响规律以及微晶玻璃的析晶过程.污泥–高炉渣微晶玻璃最佳热处理条件是850℃下形核保温1 h,980℃下析晶保温2 h.在此条件下制备的微晶玻璃具有45 MPa的抗折强度、200 MPa的抗压强度和质量损失率小于0.2%的耐酸和耐碱性能.微晶玻璃初始结晶温度为880℃,析出晶相以钙长石为主,同时包括少量的钙铝黄长石.随着析晶温度提高,析晶时间增加,钙铝黄长石相析晶量增加;大量增加的钙铝黄长石针状晶体呈放射状分布并有利于产品抗弯强度的提高;但析晶时间过长时,晶粒将长大粗化,这不利于微晶玻璃性能的改善.

Synergistic preparation of glass ceramics from sewage sludge incineration ash and blast furnace slag

Sewage sludge incineration ash is comprised of large amounts of SiO₂, a certain amount of P and many kinds of heavy metals. By utilizing sewage sludge incineration ash as the composition adjustment agent, nucleation agent and flux, glass ceramics with good mechanical performance and chemical stability were successfully synthesized by synergistic preparation with blast furnace slag without adding any chemicals. The influence of heat treatments on the glass-ceramic properties and the crystallization process of the glass ceramics were studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), mechanical properties test, and chemical stability test. It is found that the optimum heat treatment condition for preparing the glass ceramics is heating at 850~C for 1 h as a nucleation and sintering process and then heating at 980~C for 2 h as a crystallization process. Under this heat regime, the glass ceramics have the best performance with the rupture strength of 45 MPa, the compressive strength of 200 MPa and the mass lost rate of acid or alkali resistant of less than 0.2%. The initial crystallization temperature of the glass ceramics is 880~C, and crystalline phases in the glass ceramics mainly contain anorthite and a small amount of gehlenite. However the proportion of gehlenite in the glass ceramics increases with the crystallization temperature raising and the crystallization time prolonging. The gehlenite shows a radial needle-like structure, which can contribute to the improvement in bending strength of glass ceramics; but too long crystallization time is harmful to their properties due to grain growth and coarsening.