拜耳法赤泥不同脱碱工艺的对比分析

赤泥是氧化铝冶炼工业中排放的强碱性固体废弃物，为了降低赤泥中碱的含量，实现赤泥综合利用，对二氧化碳浸出法、酸中和法、钙离子置换法等脱碱工艺进行了初步的对比研究。结果表明，二氧化碳浸出法能够降低赤泥浆的pH，并有效去除赤泥中的钠（I）；盐酸的加入可以大幅度降低赤泥浆的pH，进一步水洗虽然能基本去除赤泥中的钠（I），但pH会增加；钙化合物的添加能有效置换出赤泥中的结合碱，但对赤泥浆pH的影响不大。

Comparison study on different de-alkalization processes of red mud by Bayer process

Red mud is a strong basic solid waste residue discharged in alumina refinery industry.In order to reduce the alkali content of red mud and realize the comprehensive utilization of red mud,a preliminary comparison study on several de-alkalization processes,such as CO2 extraction method,acid neutralization method,and Ca2+ replacement method was carried out.Results showed that CO2 extraction method could reduce pH of the red mud slurry and remove Na+ effectively;hydrochloric acid neutralization method was more effective for reducing pH of red mud slurry and through washing by water after acid neutralization,Na+ could be reduced substantially,but pH was increased;Ca2+ replacement method had a better effect on displacing combined alkali in red mud,but had little influence on pH.