石英砂颗粒流化磨损特性和机制实验研究

Experimental study on fluidized attrition characteristicsand mechanism of quartz sand particles

针对颗粒磨损过程中的体相断裂和表面剥层2种主要机制,设计流化床冷态实验系统,并开展石英砂颗粒磨损实验,探究操作参数、颗粒性质等因素对颗粒流化磨损的影响规律.结果表明:在快速磨损阶段,体相断裂和表面剥层均对石英砂颗粒磨损有明显影响,粒度变化速率大且产生大量细粉,体相断裂产生颗粒的质量分数明显小于表面剥层产生细粉的质量分数,因而表面剥层在快速磨损阶段是主导机制;粒度变化速率随表观气速的增加而增大,与初始粒径的关系不明显.进入稳态磨损阶段后,石英砂磨损的主导机制仍为表面剥层,体相断裂机制对颗粒流化磨损几乎没有贡献,粒度变化速率不再随表观气速、初始粒径而发生变化.基于实验数据结果,提出了适用于预测石英砂颗粒流化磨损的数学模型.

A fluidized bed cold experimental system was designed to carry out quartz sand particle attrition experiments and investigate the effects of operating parameters,particle properties and other factors on the particle attrition process,focusing on two main mechanisms of particle attrition,fragmentation and abrasion.The results show that both fragmentation and abrasion play a significant role in the rapid attrition stage,the size change rate is large and a large amount of fine powder is produced.Meanwhile,the mass fraction of particles produced by fragmentation is obviously smaller than that of fine powder produced by abrasion,and thus abrasion is the dominant mechanism.The change rate of particle size increases with the increase of apparent gas velocity,and has no obvious relationship with the initial particle size.After entering the steady-state attrition stage,the dominant attrition mechanism of quartz sand is still abrasion,the fragmentation mechanism has little contribution to the particle fluidization attrition,and the particle size change rate does not change with the apparent gas velocity and initial particle size.Based on the experimental data,a mathematical model suitable for predicting fluid attrition of quartz sand particles is proposed.