低品位石灰石溶解特性及动力学模型

Dissolution reactivity and kinetic model of low-grade limestone

石灰石资源的不可创造和不可再生导致优质石灰石资源逐渐稀缺,石灰石品位不断下降。低品位石灰石应用导致脱硫系统效率下降已逐渐成为行业内的频发事故。为明晰低品位石灰石脱硫浆液在酸性环境下的溶解动力学,开展了溶解体系温度、pH以及石灰石颗粒粒径等关键因素对低品位石灰石溶解特性的影响规律研究。结果表明,CaMg(CO_(3))_(2)是低品位石灰石中存在的主要杂质,其在酸性环境中的溶解速率远低于CaCO_(3);由CaMg(CO_(3))_(2)形成的惰性残留层决定了低品位石灰石的溶解过程主要由产物层内扩散控制。此外,基于未反应核的收缩模型,建立了低品位石灰石的半经验溶解动力学方程。

The non-creation and non-regeneration of limestone resources lead to the shortage of high-grade limestone and the continuous decline of limestone grades.The application of low-grade limestone leads to a decrease in the efficiency of the desulfurization system,which has gradually become a frequent accident in the industry.In order to study the dissolution kinetics of low-grade limestone in acidic environment,the effects of experimental variables including reaction temperature,slurry pH and initial particle size are investigated,respectively.The results show that the dolomite[CaMg(CO_(3))_(2)]is the main impurity in low-grade limestone which has a much lower dissolution rate than that of CaCO_(3)in acidic environment.The dissolution process of low-grade limestone is mainly controlled by the internal diffusion.In addition,a semi empirical dissolution kinetic equation of low-grade limestone is established based on the shrinkage model of unreacted core.