废气和废渣协同作用脱钠反应特性及机制研究

以氧化铝冶炼过程中排出的碱性固体废渣赤泥为研究对象,利用烟气中CO2对其进行了脱钠工艺的实验分析.研究了在不同pH、反应时间和温度下废气中CO2与废渣赤泥协同作用脱钠反应特性及机制,结果表明,赤泥脱钠反应过程是赤泥中钠基固体物质与CO2-H2O和OH--CO2系统协同作用的结果,脱钠过程与pH值、温度和反应时间有一定的反应规律.采用XRD和SEM方法对赤泥脱钠前后物料特性进行表征分析,结果表明赤泥中的碱性物质与CO2发生反应,赤泥脱钠后固相中的钠含量明显降低.通过合理的设计和适当的操作,可使赤泥脱钠率达70%以上,为低成本赤泥脱钠提供了一种有效的途径.

Characteristics and Mechanism of Sodium Removal by the Synergistic Action of Flue Gas and Waste Solid

The carbon dioxide (CO₂) in flue gas was used to remove the sodium in the red mud (RM), a kind of alkaline solid waste generated during alumina production. The reaction characteristics and mechanism of sodium removal by the synergistic action of CO₂ and RM were studied with different medium pH, reaction time and temperature. It was demonstrated that the remove of sodium by RM was actually the result of the synergistic action of sodium-based solid waste in RM with the CO₂-H₂O and OH^--CO₂systems. The sodium removal efficiency was correlated with pH, reaction temperature and time. The characteristics of RM before and after sodium removal were analyzed using X-ray diffractometer (XRD) and scanning electron microscope (SEM), and the results showed that the alkaline materials in the red mud reacted with CO₂ and the sodium content in solid phases decreased significantly after reaction. The sodium removal efficiency could reach up to 70% with scientific procedure. The results of this research will offer an efficient way for low-cost sodium removal.