粉煤灰中硅锂镓的碱溶特性研究

Study on Alkali-soluble Properties of Si-Li-Ga Coal Fly Ash

研究了常压下粉煤灰中硅锂镓在NaOH溶液中的溶出特性。利用XRD和SEM对粉煤灰碱溶后的物相和形貌进行表征。采用正交试验方法,研究NaOH溶液质量分数、液固比(NaOH溶液体积与粉煤灰的质量比)、反应时间和反应温度对SiO_2、Li^+和Ga^(3+)溶出率的影响,并对正交试验结果进行了极差分析。结果表明,常压下,SiO_2溶出率的最优方案为100℃下,反应3h,液固比为3∶1,氢氧化钠溶液质量分数为30%,SiO_2溶出率为44.58%。Li^+溶出率的最优方案为100℃下,反应3h,液固比为3∶1,氢氧化钠溶液质量分数为20%,Li^+溶出率为31.57%。Ga^(3+)溶出率的最优方案为80℃下,反应2h,液固比为3∶1,氢氧化钠溶液质量分数为20%,Ga^(3+)溶出率为22.87%。

The dissolution characteristics of Si-Li-Ga from coal fly ash in NaOH solution was studied.The leached residues obtained under different alkali-soluble conditions were characterized by XRD(X-ray diffractometry)and SEM(scanning electron microscope).The orthogonal test was applied.The effects of NaOH concentration,liquid to solid ratio(mass ratio of NaOH solution to fly ash),reaction time and reaction temperature on the dissolution rate of SiO2,Li+and Ga3+were studied.The results show that under the atmospheric pressure,the optimal scheme is as follows:100℃of reaction temperature,3 h of reaction time,3∶1 of liquid-solid ratio,and 20 wt%NaOH solution.And on the optimal condition,SiO2 dissolution rate is up to 44.58%.The optimum scheme of Li+dissolution rate is that at 100℃for 3 h,the ratio of liquid to solid is 3∶1,NaOH concentration is 20 wt%,and the corresponding dissolution rate of lithium is 31.57%.The optimum scheme for Ga3+dissolution rate is at 80℃for 2 h,the ratio of liquid to solid is 3∶1,NaOH concentration is 20%,and the relevant gallium dissolution rate is 22.87%.