添加NaFeO_(2)回收赤泥中氧化铝和碱水热过程

Hydrothermal for recovering alumina and alkali from Bayer red mud by adding NaFeO_(2)

为实现拜耳法赤泥的资源化利用,采用高压水化学法并添加NaFeO_(2)回收赤泥中Al_(2)O_(3)和碱,研究了反应温度、反应时间、苛碱浓度和铁酸钠添加量对该过程的影响,并通过响应曲面法对回收工艺进行优化并验证。研究结果表明,各因素对Al_(2)O_(3)提取率影响的大小顺序为:NaFeO_(2)添加量>反应时间>反应温度>苛碱浓度;在反应温度280℃、反应时间120 min、苛碱浓度220 g/L、NaFeO_(2)添加量为总质量20%的最佳工艺条件下,Al_(2)O_(3)和碱的回收率分别为74%和91%,验证实验结果与预测值基本一致。表征结果表明,回收赤泥中Al_(2)O_(3)和碱的原理为赤泥中的水合铝硅酸钠通过水化反应转变成铁水化石榴石。

In order to utilize the red mud from Bayer process,the alumina and alkali extraction were extracted by the process of high pressure water chemical.The effect of reaction temperature,reaction time,Nk concentration and the addition of NaFeO2 were investigated,and the extraction process was optimized by response surface methodology.The results show that the order of the influence for factors on the extraction rate of alumina are as follows:the addition of NaFeO2>reaction time>reaction temperature>Nk concentration.And the extraction rates of alumina and alkali are 74%and 91%,respectively,under the conditions of reaction temperature of 280℃,reaction time of 120 min,Nk concentration of 220 g/L and the addition of NaFeO2 of 20%for total mass.The predictions are in general agreement with the experimental results.More importantly,the principle of recovering alumina and alkali from red mud is that the 1.0Na2O·Al_(2)O_(3)·1.68SiO_(2)·1.7H2O phase in red mud would be converted to Ca3(Fe0.87Al0.13)2(SiO4)1.65(OH)5.4 phase through hydrothermal process.