碱酸法处理铝电解废防渗料

doi:10.12068/j.issn.1005-3026.2025.20230344

摘要/Abstract

摘要：

提出了碱酸浸出处理铝电解废防渗料的工艺.以某铝厂废防渗料为原料，分析其主要物相为NaF，NaAlSiO₄，CaF₂，α-Al₂O₃，Na₃AlF₆，Si和β-Al₂O₃.首先，原料水浸分离得到质量分数为98.84%的NaF.其次，采用单因素法得到碱浸处理水浸渣的最优工艺条件为温度90 ℃、液固比5 cm³/g、碱渣质量比0.25、反应时间100 min，该条件下Na₃AlF₆浸出率为94.04%.再次，通过单因素法得到酸浸处理碱浸渣的最优工艺条件为温度58 ℃、反应时间45 min、酸浓度0.6 mol/L、液固比12 cm³/g，该条件下NaAlSiO₄和CaF₂可被浸出.将碱浸液滴入酸浸液中除去酸浸液中的硅，当pH约为3时酸浸液中硅溶胶沉淀效果最好，过滤后加热硅溶胶，产物主要为SiO₂·0.2Al₂O₃，质量分数为97.20%.将过滤去除硅溶胶后的酸浸液加入碱浸液中沉淀回收氟盐，当pH为9时，CaF₂和Na₃AlF₆的回收率最高，分别为95.91%和92.44%，质量分数分别为48.41%和25.14%，此外，沉淀物中还含有质量分数为25.32%的Al(OH)₃.

关键词: 铝电解, 废防渗料, 碱酸法, 硅溶胶, 资源化利用

Abstract:

The process of treating spent dry barrier from aluminum electrolysis with alkali and acid is proposed. Spent dry barrier sample from an aluminum company was taken as the raw material， and its main phases are NaF， NaAlSiO₄， CaF₂， α-Al₂O₃， Na₃AlF₆， Si and β-Al₂O₃. Firstly， the NaF with mass fraction of 98.84% is obtained by water leaching separation of the raw materials. Secondly， the optimal process condition for alkali leaching treatment of water leaching residue were obtained by single factor method as follows： temperature of 90 ℃， liquid-solid ratio of 5 cm³/g， alkali-slag mass ratio of 0.25， and reaction time of 100 min， and under this condition， the leaching rate of Na₃AlF₆ was 94.04%. After that， the optimal process conditions for acid leaching treatment of alkali leaching residue were obtained by single factor method as follows： temperature of 58 ℃， reaction time of 45 min， acid concentration of 0.6 mol/L， and liquid-solid ratio of 12 cm³/g， and under this condition， NaAlSiO₄ and CaF₂ can be leached. Subsequently， the alkali leaching solution was dropped into the acid leaching solution to remove silicon in the acid leaching solution. It was found that when the pH was about 3， the precipitation effect of silica sol in the acid leaching solution was the best， and the product obtained by heating the silica sol which was obtained through filtering was mainly SiO₂·0.2Al₂O₃， with a mass fraction of 97.20%. The acid leaching solution after filtering to remove the silica sol was added to the alkali leaching solution to precipitate and recover the fluoride salts， and it was found that when the pH was 9， the recovery rates of CaF₂ and Na₃AlF₆ were the highest， which were 95.91% and 92.44%， respectively， and the mass fractions were 48.41% and 25.14%， respectively. In addition， the precipitate contains 25.32% （mass fraction） of Al（OH）_3.

Key words: aluminum electrolysis, spent dry barrier, alkali-acid method, silica sol, resource utilization

中图分类号:

TF 09

苏克箭, 胡宪伟, 张俊宇, 王兆文. 碱酸法处理铝电解废防渗料[J]. 东北大学学报（自然科学版）, 2025, 46(6): 40-49.

Ke-jian SU, Xian-wei HU, Jun-yu ZHANG, Zhao-wen WANG. Treatment of Spent Dry Barrier from Aluminum Electrolysis by Alkali-Acid Method[J]. Journal of Northeastern University(Natural Science), 2025, 46(6): 40-49.

图/表 24

表1 实验所使用的分析仪器

Table 1 Analytical instruments used in the experiment

仪器	生产厂家	型号
X射线衍射仪	日本理学(Rigaku)公司	Smartlab SE
高频燃烧红外碳硫分析仪	美国LECO(力可)公司	CS244
原子吸收分光光度计	日本日立公司	180-80
电感耦合等离子体发射光谱仪	美国Perkin Elmer公司	Optima 4300D
扫描电子显微镜	德国蔡司显微镜有限公司	ULTRA PLUS

图1 铝电解废防渗料的XRD图谱

Fig.1 XRD pattern of spent dry barrier from aluminum electrolysis

表2 铝电解废防渗料的元素含量（质量分数） (%)

Table 2 Element content of spent dry barrier from aluminum electrolysis (mass fraction)

Na	F	Ca	Al	Fe	Li	C	Si	O	余量
25.63	22.90	5.73	10.46	0.96	0.18	0.30	15.06	17.02	1.76

图2 铝电解废防渗料中可溶组分的XRD图谱

Fig.2 XRD pattern of soluble components in spent dry barrier form aluminum electrolysis

图3 水浸后剩余固相的XRD图谱

Fig.3 XRD pattern of the remaining solid phase after water leaching

表3 碱浸、酸浸实验参数设置

Table 3 Parameter settings for alkali and acid leaching experiments

浸出步骤	温度/℃	时间/min	碱渣质量比	浸出液浓度	液固比	搅拌速率
浸出步骤	温度/℃	时间/min	碱渣质量比	mol·L^-1	cm³·g ^-1	r·min^-1
碱浸	40⁓100	20⁓140	0.1⁓0.35	—	2⁓6	300
酸浸	室温⁓70	15⁓60	—	0.375⁓0.675	8⁓14	300
浸出液处理	室温	实时反应	—	—	—	200

图4 温度对Na3AlF6浸出率的影响

Fig.4 Effect of temperature on leaching rate of Na3AlF6

图5 浸出时间对Na3AlF6浸出率的影响

Fig.5 Effect of leaching time on leaching rate of Na3AlF6

图6 碱渣质量比对Na3AlF6浸出率的影响

Fig.6 Effect of alkali-slag mass ratio on leaching rate of Na3AlF6

图7 液固比对Na3AlF6浸出率的影响

Fig.7 Effect of liquid-solid ratio on leaching rate of Na3AlF6

图8 碱浸后典型滤渣的XRD图谱

Fig.8 XRD pattern of typical residue after alkaline leaching

图9 温度对NaAlSiO4和CaF2浸出率的影响

Fig.9 Effect of temperature on leaching rates of CaF2 and NaAlSiO4

图10 硅溶胶的线性生长及交联过程的模型

Fig.10 Modeling of linear growth and cross-linking process of silica sols

图11 浸出时间对CaF2和NaAlSiO4浸出率的影响

Fig.11 Effect of leaching time on leaching rates of CaF2 and NaAlSiO4

图12 酸浓度对CaF2和NaAlSiO4浸出率的影响

Fig.12 Effect of acid concentration on leaching rates of CaF2 and NaAlSiO4

图13 液固比对CaF2和NaAlSiO4浸出率的影响

Fig.13 Effect of liquid-solid ratio on leaching rates of CaF2 and NaAlSiO4

图14 酸浸后典型渣相的XRD图谱

Fig.14 XRD pattern of typical residue after acid leaching

表4 酸浸液中硅元素的沉淀率随pH的变化

Table 4 Variation of precipitation rate of silicon element in acid leaching solution with pH

pH	2.02	2.29	2.44	2.58	2.71	2.83	2.92	3.03	3.09
Si沉淀率/%	0	19.23	40.77	72.33	84.92	89.65	95.41	98.06	98.11

图15 酸浸液凝胶化后所得产物的XRD图谱

Fig.15 XRD pattern of product obtained after solution gelation

图16 酸浸液中硅凝胶化沉淀物的形貌图

Fig.16 Morphology of silica coagulation precipitate in acid leaching solution

图17 去除硅溶胶的酸浸液加入碱浸液后所得沉淀物的XRD图谱

Fig.17 XRD pattern of precipitate obtained by adding alkali leaching solution to acid leaching solution after silica sol removal

表5 EDS和ICP测得酸浸液中硅凝沉淀产物中Si和Al的质量分数

Table 5 Mass fraction of Si and Al in silica coagulation precipitation products in acid leaching solution measured by EDS and ICP %

元素	EDS		ICP
元素	点1	点2	ICP
Al	8.44	9.06	8.76
Si	38.95	37.45	37.69

图18 沉淀物中氟盐（CaF2，Na3AlF6）回收率随pH变化

Fig.18 Variation of fluoride salts (CaF2，Na3AlF6) recovery rate with pH in precipitate

表6 25 ℃下CaF2，Na3AlF6，Al(OH)3的溶度积[29] (Al(OH)3 at 25 ℃[29])

Table 6 Solubility products of CaF2， Na3AlF6 and

种类	溶度积 $K s p$
CaF₂	3.90×10^-10
Na₃AlF₆	4.22×10^-10
Al(OH)₃	1.30×10^-33

表6 25 ℃下CaF2，Na3AlF6，Al(OH)3的溶度积[29] (Al(OH)3 at 25 ℃[29])

Table 6 Solubility products of CaF2， Na3AlF6 and

种类	溶度积 $K s p$
CaF₂	3.90×10^-10
Na₃AlF₆	4.22×10^-10
Al(OH)₃	1.30×10^-33

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