Development of A New Lime Adding Technology in Two-Stream Digestion Process of Diasporic Bauxite

Indirect heating and intensified digestion technology can be applied to reduce greatly the energy consumption in Bayer process of diasporic bauxite. A great advantage of two-stream process is to avoid or reduce efficiently serious scaling problem of bauxite slurry on indirect heating surface, which certainly happens in the single stream process and brings about great troubles to the indirect heating. As a result of a great number of experiments and the theoretical analysis, a new lime adding technology for the two-stream digestion process is developed in this paper that lime is added into spent liquor stream instead of bauxite slurry, which is more suitable to the two-stream process of diasporic bauxite. The influences of the new lime addition technology on preheating and digestion process were discussed. It was deduced that the new technology can be used efficiently in the two-stream process of non-diasporic bauxite.

中低品位铝土矿石灰拜耳法溶出的研究

对铝硅比为5.36的一水硬铝石型铝土矿进行了常规拜耳法和石灰拜耳法的溶出对比研究,主要分析了石灰添加量和预脱硅对铝土矿溶出赤泥成分的影响.结果表明,随着石灰添加量的增加,溶出赤泥的铝硅比呈明显的线性上升趋势,而钠硅比则呈下降趋势,且钙硅比小于2.0时,钠硅比呈近似直线迅速下降,当钙硅比大于2.0时,钠硅比变化逐渐变缓;石灰拜耳法溶出赤泥物相主要以水合铝硅酸钙为主,而常规拜耳法溶出赤泥主要以水合铝硅酸钠为主.预脱硅4 h可使溶出赤泥铝硅比从1.53降低到1.43,钙硅比可从0.28降低到0.24.

石灰拜耳法赤泥沉降性能的研究

赤泥的沉降性能是关系到氧化铝生产过程能否顺行的重要指标之一。研究了石灰拜耳法新工艺过程中的赤泥沉降压缩性能 ,结果表明石灰拜耳法工艺过程的赤泥沉降性能略逊于常规拜耳法 ,但赤泥压缩性能良好 。

不同添加剂对某铝土矿拜耳法溶出性能的研究

对不同添加剂(铁酸二钙、氧化镁、水化铁酸钙、赤泥磁选氧化铁的水化铁酸钙)替代石灰对国内某铝土矿的拜耳法溶出性能影响进行了研究。结果表明,水化铁酸钙完全替代石灰效果最佳,当按C/S=1. 3添加时,赤泥中N/S降至0. 31,A/S降至1. 2,溶出率提升至96. 91%。根据其研究结果,优化生产工艺,为生产氧化铝的企业提供节能减排增产参考。