石灰石分解特性及微观结构迁移规律研究

Study of the Decomposition Characteristics of Limestone and the Law Governing the Migration of the Microscopic Structure

采用自建的热重分析仪进行石灰石煅烧分解的热重实验,得到了温度、煅烧气氛及粒径对石灰石分解过程的影响规律,利用扫描电镜(scanning electron microscopy,SEM)和比表面积及孔隙度分析仪重点考察了分解过程中煅烧产物微观结构的迁移变化规律。研究表明:温度是影响石灰石煅烧的关键因素,温度越高,反应越快;CO2分压和粒径的增大对石灰石分解反应有一定的抑制作用;石灰石煅烧产物比表面积和比孔容随煅烧时间的延续快速增加。超过完全分解时间继续煅烧,煅烧产物产生烧结,比表面积和比孔容减小;原始石灰石几乎为无孔形态,随着煅烧过程的进行,微孔、中孔和大孔出现,呈双峰结构分布,煅烧开始至2.5 min时段内中孔增长较多,2.5～6.5 min时段内微孔和大孔快速生成,烧结导致孔的数量减少。

By using a self-made thermogravimetric analyzer,a thermogravimetric test of the calcination and decomposition of limestone was conducted with the law governing the influence of temperature,calcination atmosphere and particle diameter on the decomposition process of limestone being obtained.Furthermore,by using a scanning electron microscope(SEM) and a specific surface area and porosity analyzer,the variation law governing the migration of the microscopic structure of the product obtained during the calcination and decomposition process was mainly investigated.The research results show that temperature is a key factor influencing the calcination of limestone,the higher the temperature,the quicker the reaction.The pressure component of carbon dioxide and an increase of the particle diameter can play a certain role in prohibiting the decomposition reaction of limestone.The specific surface area and pore volume of the product produced during the calcination of limestone will quickly increase with the continuation of the calcination.If going on calcinating after exceeding the time required for a total decomposition,the product of the calcination of limestone will begin to sinter,the specific surface area and pore volume will decrease.The original limestone has almost no pores.However,with the continuation of the calcination,micro-pore,middle-sized pores and big pores will emerge,assuming a dual-peak structure distribution.From the beginning to 2.5 min of the calcination,the middle-sized pores will increase in a relatively large quantity and during the time from 2.5 min to 6.5 min,the micro-pores and big pores will quickly come into being,however,the sintering will lead to a reduction of the number of the pores.