洁净煤技术

2019, (04) 137-144

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高铝粉煤灰碱法提铝过程镓的吸附研究
Adsorption of gallium in alkali extraction of aluminum from high alumina fly ash

竹小宇;黄科林;孙振华;李少鹏;李会泉;文朝璐;张建波;
ZHU Xiaoyu,HUANG Kelin,SUN Zhenhua,LI Shaopeng,LI Huiquan,WEN Chaolu,ZHANG Jianbo

摘要(Abstract):

我国内蒙古中西部以及山西北部地区的高铝粉煤灰中氧化铝含量高达50%以上,伴生的镓含量可达60 mg/kg,是重要的含铝、镓二次资源。为进一步提升高铝粉煤灰资源化利用附加值,实现粉煤灰提铝过程低浓度含镓溶液的高效提取,本文基于高铝粉煤灰预脱硅拜耳-亚熔盐联合法提铝工艺中的含镓碱液体系,研究了含镓模型溶液中镓离子的静态吸附规律,系统考察了不同吸附时间、吸附温度、镓初始浓度以及碱浓度对螯合树脂吸附镓离子的影响,完成了吸附动力学与吸附等温线的考察,并采用吸附柱进行了低浓度含镓碱液动态吸附及淋洗试验验证。静态吸附试验结果表明:采用LSC-600型螯合吸附树脂可实现低浓度含镓碱液中镓离子的高效吸附,树脂的平衡吸附容量随静态吸附时间增大而增大,吸附24 h后树脂吸附容量达到平衡;镓离子初始浓度低于400 mg/L,树脂的平衡吸附容量受吸附温度影响较小,在镓离子浓度高于400 mg/L体系中,树脂的平衡吸附容量随吸附温度升高而降低,其中吸附温度为50℃时树脂对镓离子的平衡吸附容量最大;随含镓碱液碱浓度增加,螯合树脂对镓离子的吸附容量先增大后减小,螯合树脂对镓离子的平衡吸附容量随镓离子初始浓度增大而增大,镓离子初始浓度高于1 200 mg/L时树脂吸附容量达到饱和,吸附温度为50℃,镓离子初始浓度为1 200 mg/L,碱浓度为5 mol/L时树脂的最大吸附容量为36 mg/g。动力学拟合结果表明:碱体系树脂对镓离子的吸附动力学过程符合准二级动力学方程,属于化学吸附过程;吸附等温线拟合结果表明,LSC-600型螯合树脂对镓离子的吸附满足Langmuir等温方程,说明镓离子的螯合吸附过程为单层吸附。树脂的动态吸附和淋洗结果表明,液体流速越大,树脂达到吸附平衡时的穿透床层数越小,树脂对镓离子的吸附容量和吸附率均较低,镓离子初始浓度50 mg/L,吸附温度为50℃,吸附流速为2. 5 BV/h时,树脂对低浓度含镓碱液吸附效果最优,最大吸附容量为3. 13 mg/g,淋洗过程淋洗液镓离子浓度随着床层数增加先增大后降低,淋洗流出液达到0. 7 BV时镓浓度最高为1 936mg/L,高浓度段(0. 3~1. 5 BV)溶液中镓离子浓度为1 248 mg/L,富集倍数达25倍。
The high alumina fly ash is mainly generated in central and western Inner Mongolia Autonomous region and the northern Shanxi province,in which the content of alumina is up to 50%.The associated content of gallium can reach 60 mg/kg,which is an important secondary resource containing aluminum and gallium.In order to elevate the value of resource utilization and realize the high efficiency extraction of low concentration gallium solution during the process of alumina extraction,the gallium containing alkali liquid system of high alumina fly ash Pre-desilication-Bayer-Sub-molten salt method was investigated in the aluminum process.The static adsorption law of gallium ions in gallium containing model solution was studied,and the effects of different adsorption time,adsorption temperature,initial concentration of gallium and alkali concentration on the adsorption of gallium ions by chelated resin were systematically investigated.The dynamic adsorption and elution tests of gallium alkalic liquid with low concentration were verified by using adsorption column.The results of static adsorption show that the high efficiency of gallium ions containing gallium in low concentration can be achieved by using LSC-600 chelating resin.The equilibrium adsorption capacity of gallium ions with an initial concentration of less than 400 mg/L resin is less affected by the adsorption temperature.In the system of a gallium ion concentration higher than 400 mg/L,the equilibrium adsorption capacity of the resin decreases with the temperature of adsorption.The equilibrium adsorption capacity of gallium ions is the largest when the adsorption temperature is 50 ℃.With the increase of the concentration of NaOH,the adsorption capacity of gallium ions by chelating resin increases in the first period and then decreases in the last period.The equilibrium adsorption capacity of gallium ions by chelating resin increases with the initial concentration of gallium ions.The initial concentration of gallium ions is higher than 1 200 mg/L.The adsorption capacity of the resin is saturated.When the adsorption temperature is 50 ℃,the initial concentration of gallium ions is 1 200 mg/L,and the maximum adsorption capacity of the resin is 36 mg/g when the base concentration is 5 mol/L.The kinetic fitting results show that the adsorption kinetics of gallium ions by alkali resin conforms to the quasi-secondary kinetic equation and accords with the chemical adsorption process.The adsorption isotherm fitting results show that the adsorption of gallium ions by LSC-600 chelating resin conforms to the Langmuir isothermal equation,which indicats that the chelation adsorption process of gallium ions belongs to single-layer adsorption.The dynamic adsorption and eluting results of the resin show that the liquid flow rate is increased with the decrease of the volume of adsorption bed when the resin reaches the adsorption equilibrium.When the initial concentration of gallium ions,adsorption temperature and adsorption flow rate are 50 mg/L,50 ℃ and 2.5 BV/h,respectively,the resin has the best adsorption effect on alkali solution containing the low concentration gallium ion,and the maximum adsorption capacity is 3.13 mg/g.The concentration of gallium ions in the eluting solution increases and then decreases with the increase of bed layer number.The maximum concentration of gallium is 1 936 mg/L when eluting solution is 0.7 BV.The concentration of gallium in the solution of the high concentration (0.3-1.5 BV) is 1 248 mg/L,and the concentration ratio is up to 25.

关键词(KeyWords): 高铝粉煤灰;碱法;镓;吸附
high aluminum fly ash;alkali method;gallium;adsorption

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作者(Author): 竹小宇;黄科林;孙振华;李少鹏;李会泉;文朝璐;张建波;
ZHU Xiaoyu,HUANG Kelin,SUN Zhenhua,LI Shaopeng,LI Huiquan,WEN Chaolu,ZHANG Jianbo

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