在活性炭掺量为10%~15%,煅烧温度为1100~1250 ℃条件下,从动力学和热力学角度对磷石膏分解煅烧制胶凝材的可行性进行了研究.在该温度范围内,通过等温热分析法确定了磷石膏分解体系的表观活化能为299.88~382.85 kJ·mol-1,指前因子lnA为18.64~25.61 s-1,分解动力学方程为受三维扩散控制的Z-L-T方程.经Factsage软件计算和SEM、EDS、XRD等微观检测发现,煅烧过程中,不仅发生了硫酸钙的分解,还伴随着分解产物CaO和杂质SiO2的合成反应.根据CaO-SiO2-CaSO4相图的理论计算结果表明,适量补充硅铝质改性组分,调节生料的配比范围,有使磷石膏基水硬性复合胶凝材料强度提升的潜能.
From the kinetic and thermodynamic point of view, the feasibility of phosphogypsum(PG) decomposition making cementitious material at low temperature was studied.The decomposition kinetics of PG with 10%-15% activated carbon(AC) were investigated at 1100-1250 ℃.The results show that the apparent activation energy of PG decomposition system is 299.88-382.85 kJ·mol-1, the pre-exponential factor is 18.64-25.61 s-1 and the most possible decomposition mechanism is Z-L-T function.The synthesis reaction of CaO and SiO2 was processing along with the decomposition during the calcination was confirmed by the thermodynamic calculation and microstructural analysis.According to the phase diagram of CaO-SiO2-CaSO4 system, adding some appropriate silicon aluminum modified components and adjusting the scope of raw material proportion have the potentiality to improve the compressive strength of cementitious material made from PG.
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