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钢渣是一种大宗工业废弃物,由于存在安定性不良的缺点,利用率一直较低。该文将多聚磷酸盐改性钢渣用于蒸压尾矿砖的生产,对影响产品性能的主要因素进行了系统研究,确定了适宜的蒸压砖工艺条件和蒸养制度:成型水量为9%;成型压力为20 MPa;蒸养制度为“升温4 h-180℃恒温4 h-自然冷却降温”。蒸压砖中钢渣粉用量由原来的11%(未改性,未粉磨)提高到25%(改性),水泥用量由原来的7%下降到5%,抗压强度则由11.6 MPa大幅度提高到22.1 MPa,产品满足《粉煤灰砖》(JC 239-2001)标准要求,达到了MU20等级。多聚磷酸盐改性剂除了有效改善钢渣的安定性之外,还对钢渣和尾矿具有良好的活性激发作用,进而强化了蒸压过程中的水化反应。借助XRD和SEM分析了蒸压试块的水化产物及微观结构,探讨了改性钢渣-尾矿蒸压砖的水化与强度形成机理。
Slag is a bulk industrial waste and has been used at a lower rate due to its poor stability. In this paper, polyphosphate-modified steel slag is used for the production of autoclaved tailings brick. The main factors influencing the performance of the product are systematically studied, and the suitable autoclaved brick process conditions and steam curing system are determined: the amount of forming water is 9 %; Forming pressure of 20 MPa; steaming system for the “warming 4 h-180 ℃ constant temperature 4 h-cooled naturally cooled.” The amount of steel slag in autoclaved brick was increased from 11% (unmodified, non-pulverized) to 25% (modified), the amount of cement dropped from 7% to 5%, and the compressive strength was increased from 11.6 MPa The amplitude is increased to 22.1 MPa and the product meets the standard of “fly ash bricks” (JC 239-2001), reaching MU20 level. In addition to effectively improving the stability of the steel slag, the polyphosphate modifier also has a good active excitation effect on the steel slag and the tailings, thereby enhancing the hydration reaction in the autoclaving process. The hydration products and microstructure of the autoclave were analyzed by XRD and SEM, and the formation mechanism of hydration and strength of the modified slag - tailing autoclaved brick was discussed.