生石灰粒径对碱回收绿液消苛化反应的影响及工程实践

Effect of Lime Particle Size on the Caustic Reaction of Green Liquid in Alkali Recovery and Its Engineering Practice

关键词:  碱回收  绿液  苛化  生石灰  粒径

Key Words:alkali recovery  green liquid  causticization  lime  particle size

摘要:本研究探索了生石灰粒径对碱回收过程绿液消化反应和苛化反应的影响，并在实际生产过程中进行实践。结果表明，粒径较小的生石灰能够促进绿液的消化反应和苛化反应。随着生石灰粒径的减小，绿液消化过程温度增幅由15.0 ℃增加到19.0 ℃，升温时间由240 s减少到190 s，消化渣有效CaO含量由17.8%降低到7.2%。苛化后白液中活性碱含量由128.0 g/L提高到131.5 g/L，苛化度由76.5%提高到78.8%。但较小粒径的生石灰苛化后产生的白泥粒径也较小，不利于白液的澄清，因此应合理控制生石灰粒径。在实际生产实践中，利用粉状生石灰替换块状生石灰，可简化生石灰系统，使白液中活性碱含量和苛化度分别提高了2.0 g/L和2.5个百分点，生石灰系统运行费用降低4 980元/天。

Abstract:In this study， the effects of lime particle size on the digestion and causticization reactions of green liquid in alkali recovery processes were investigated， and industrial practice in the actual production process was explored. The results showed that lime with smaller particles could promote the digestion and causticization reactions of green liquid. As the particle size of lime decreased， the temperature ampufication during the green liquid digestion process increased from 15.0 to 19.0 ℃， the heating time decreased from 240 to 190 s， and the effective calcium oxide content of the digestion slag decreased from 17.8% to 7.2%. The active alkali content of the white liquid after causticization increased from 128.0 to 131.5 g/L， and the causticity degree increased from 76.5% to 78.8%. However， the particle size of white sludge produced after causticization with smaller lime particle size was also small， which was not conducive to the clarification of white liquid， so the lime particle size should be reasonably controlled. In actual production practice， replacing bulk lime with powdered lime simplified the lime system， the active alkali content and causticity of the white liquid were increased by 2.0 g/L and 2.5 percentage points， respectively， and the daily operating cost of the lime system was reduced by 4 980 RMB.