李子良, 徐志峰, 张溪, 昝苗苗, 刘志楼. 酸性含汞溶液中电沉积回收汞的研究[J]. 工程科学学报, 2020, 42(8): 999-1006. DOI: 10.13374/j.issn2095-9389.2020.03.15.001
引用本文: 李子良, 徐志峰, 张溪, 昝苗苗, 刘志楼. 酸性含汞溶液中电沉积回收汞的研究[J]. 工程科学学报, 2020, 42(8): 999-1006. DOI: 10.13374/j.issn2095-9389.2020.03.15.001
LI Zi-liang, XU Zhi-feng, ZHANG Xi, ZAN Miao-miao, LIU Zhi-lou. Mercury recovery from acidic mercury solution using electrodeposition[J]. Chinese Journal of Engineering, 2020, 42(8): 999-1006. DOI: 10.13374/j.issn2095-9389.2020.03.15.001
Citation: LI Zi-liang, XU Zhi-feng, ZHANG Xi, ZAN Miao-miao, LIU Zhi-lou. Mercury recovery from acidic mercury solution using electrodeposition[J]. Chinese Journal of Engineering, 2020, 42(8): 999-1006. DOI: 10.13374/j.issn2095-9389.2020.03.15.001

酸性含汞溶液中电沉积回收汞的研究

Mercury recovery from acidic mercury solution using electrodeposition

  • 摘要: 针对有色金属冶炼烟气中湿法脱汞过程产生的硫脲汞溶液难处置的问题,研究提出了电沉积从硫脲汞溶液中回收汞的新工艺。采用线性电位扫描法得到汞电沉积过程的阴极极化曲线,考察了不同杂质离子对硫脲汞溶液阴极极化曲线的影响。结果显示,在控制阴极电位为−0.55~−0.45 V的条件下,溶液中的汞可选择性沉积,溶液中Fe3+、Cu2+和H2SO3并不会影响溶液中汞的电沉积,即汞选择性电沉积的电位为−0.55~−0.45 V。采用控电位技术对硫脲汞溶液电解回收汞工艺进行研究,探究了电解质种类和浓度、电解液温度、搅拌速率、电解时间等因素对汞回收效率的影响。得到在阴极材料为铜片的条件下,最佳的电解工艺参数:电解质为0.24 mol·L−1 Na2SO4,电解液温度为30~40 ℃,搅拌速度为100~300 r·min−1 \rmSO^2-_3浓度为8 mmol·L−1,电解时间为5 h。最佳工艺条件下,溶液中汞的回收效率可达98%以上。对阴极电解产物进行分析,阴极上的汞为单质汞,且纯度超过99%。

     

    Abstract: Mercury, a heavy metal, can seriously harm human bodies and the environment due to its characteristics of high toxicity, biological enrichment, and long-range migration. The non-ferrous metal smelting industry is one of the main sources of atmospheric mercury pollution in China. Therefore, controlling atmospheric mercury emissions from non-ferrous smelting plants is very important. The wet cleaning process has been widely applied in the purification of smelting flue gas because of its advantages such as a high removal efficiency, stable operation, and low cost. During the wet purification process, thiourea is usually added because it can reduce the oxidation potential of mercury and react with mercury to form stable coordination ions, resulting in the high-efficiency removal of mercury from high-sulfur smelting flue gas. However, mercury recovery from scrubbing solutions containing mercury and thiourea obtained from the wet cleaning process is difficult. In this study, a novel technology to recover mercury from the thiourea mercury solution via electrodeposition was proposed and investigated. The linear potential scanning method was applied to obtain the reduction potential of mercury. It was determined that the optimal potential of the mercury electrodeposition process should be controlled between −0.55 V and −0.45 V because the presence of ferric ions, copper ions, and sulfite ions did not seriously affect the electrodeposition of mercury. Controlled potential electrolysis was employed to efficiently recover mercury from thiourea mercury solution, and the effects of key parameters, including electrolyte type and concentration, electrolyte temperature, stirring rate, and electrolytic time, on the mercury recovery efficiency were explored. The optimal process conditions are as follows: a cathode material of copper sheet, electrolyte of 0.24 mol·L−1 Na2SO4, electrolyte temperature of 30–40 ℃, stirring speed of 100–300 r·min−1, \rmSO^2-_3 concentration of 8 mmol·L−1, and electrolytic time of 5 h. Under the optimal process conditions, the mercury recovery efficiency mercury is over 98%. The electrolytic products on the cathode are elemental mercury, and the corresponding purity is over 99%.

     

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