锌电积能耗及节能研究

【作者】 许春富；

【导师】 谢刚； 陈加希；

【作者基本信息】 昆明理工大学 ， 冶金物理化学， 2009， 博士

【摘要】 湿法炼锌自20世纪初投入生产以来,其技术不断发展进步,目前世界上锌总产量的85%以上都是采用此工艺生产的。但是由于湿法炼锌存在电积能耗高的缺点,为此,要加快节能环保技术进步,积极推进以节能减排为主要目标的设备更新和技术改造,就必须采用有利于节能环保的新设备、新工艺、新技术。加强资源综合利用和清洁生产,大力发展循环经济和节能环保产业。要加强发展高新技术产业,实现产业结构升级和自主创新。本论文以ZnSO4-H2SO4体系电积液为研究对象,对湿法炼锌工艺中的电积锌工艺进行了研究,主要包括以下内容：1.ZnSO4-H2SO4电积锌体系的参数优化及其能耗研究论文在分析了湿法炼锌的电积过程中影响电能消耗的条件后,主要研究了以下基本内容：(1)温度、Zn2+和硫酸浓度的变化对电积液密度的影响；(2)温度、Zn2+和硫酸浓度的变化对电积液电导率的影响；(3)Zn2+和硫酸浓度的变化对电积时槽电压的影响；(4)Zn2+和硫酸浓度的变化对电积时电流效率的影响；(5)Zn2+和硫酸浓度的变化对电积时电能消耗的影响。通过试验研究找到各参量之间的变化规律,对所得到的数据进行分析,建立回归方程。2.ZnSO4-H2SO4电积锌体系中影响锌电积的杂质行为和深度净化研究硫酸锌电积液中存在的杂质元20多种,而其中Co、Ni、As、Sb、Ge是主要影响锌产品的表面质量及电流效率的杂质。本研究采用电化学方法来研究Co、Ni、As、Sb、Ge五种杂质对锌电积阴极过程的影响。实验通过研究了含五种杂质在不同浓度和不同温度下的暂态法和稳态法的阴极极化曲线,通过测定极化曲线的数据,然后根据Tafeil和Butel-Volmer方程计算出了动力学参数。结果发现单一杂质钴在≥6mg/L、镍≥14mg/L、砷≥6mg/L、锑≥1mg/L、锗≥1mg/L时对锌电积影响显著,杂质钴、镍对锌的沉积影响最小,砷其次,锑次之,锗的影响最大。通过实验研究提出了三段深度净化工艺,可以实现溶液杂质的深度脱除。3.添加剂对ZnSO4-H2SO4电积锌体系中锌电积过程的影响研究研究明胶、十二烷基磺酸钠、硫脲等十多种试剂作为添加剂对阴极锌表面质量的影响,对取得较好效果的添加剂进行了优化组合,通过目测和照片并对其影响效果进行了评价,对其作用机理进行了研究。实验表明,明胶在电积过程中有着不可或缺的作用,相比单一的添加剂而言,复合添加剂能够取得更为理想的效果。理想的添加剂在锌电积过程中能够明显的改善阴极表面质量、提高电流效率、降低能耗并且能够抑制工业中常见的返溶现象,有一定的工业应用价值。4.镁对锌电积过程影响的研究锌电积液中电性较锌更负的Mg2+,当其浓度低时对电积无影响,一般不需除去,但镁盐会在整个湿法系统的溶液中不断循环积累,直至达到饱和,使电积液密度、粘度、电阻率都随溶液中镁离子的增大而增大,从而使得电积液电阻增大,电积的电流效率降低,电能消耗升高。论文系统研究分析了不同温度下,不同浓度的镁离子含量对电积液的密度、粘度、电导率以及电积过程的电流效率和电能消耗的影响,提供了一些实验数据,可供湿法炼锌工厂以及相关科技人员参考。5.含镁硫酸锌电积液中锌电积的反应动力学模型研究论文提出含镁硫酸锌电积液电积锌的反应动力学模型,并首次采用基于第一原理的密度泛函理论,应用CASTEP量化软件对提出的含镁硫酸锌电积液电极反应动力学模型进行理论验证。通过以上对锌电积工艺的系统研究,本研究提出了锌电积节能的一些具体措施：(1)选择优化的参数体系,即当试验条件一定时,Zn2+浓度为52g/L,硫酸浓度为134g/L时,电能消耗最小,为2961.344kW·h/t锌。(2)对电积液进行三段深度净化,净化后液可以在大于48h的电积周期下进行电积,与传统净化相比,电耗降低约150kW·h/t。(3)在电积时,向电解液中添加组合添加剂,即为硫脲和明胶,硫脲的用量为20mg/L,明胶的用量为15mg/L,电流效率可以提高3%以上,锌电积能耗降低150kW·h/t,电积周期>24h组合添加剂作用更加明显。本文的主要创新点：(1)系统深入地研究了锌电积时,温度、硫酸浓度、Zn2+浓度对电积液密度、电导率以及对电积时槽电压、电流效率和电能消耗的影响规律,建立了电积参数对电能消耗的回归方程,对锌电积的实际生产有重要的指导意义。(2)通过对杂质在锌电积中行为的系统深入研究,提出了三段深度净化的处理工艺,可以使锌电积能耗降低150kW·h/t,并对锌电积的析氢反应机理进行了研究。(3)通过对单一添加剂对锌电积过程影响规律的研究,获得了组合添加剂硫脲和明胶,采用此添加剂可以使锌电积能耗降低150kW·h/t。(4)首次对杂质镁的行为进行了研究,获得了含镁硫酸锌电积液电积锌的反应动力学模型。更多还原

【Abstract】 The technology of zinc hydrometallurgy has made progress continuously since it was put into production in industry at the early 20th century, and more than 80% total output of zinc is using this technology. Zinc hydrometallurgy has shortcomings of high energy consumption in the electrowinning process. Therefore,it’s necessary to speed up the process energy-saving and environment protection technology and actively promote the changing of equipment and technological transformation with a view energy saving and emissions reduction, so we must use the new equipment and technology which is helpful to saving energy and protecting environment, enhance the holistic utilization of resources and promote the clearer production and develop circular economy and the industry of energy saving and environmental protection technology. It’s essential to develop high technology industry energetically and achieve the optimization and upgrading of the industrial structure and independent innovation.The dissertation regards ZnSO4-H2SO4 system as the object of study, and research the technology of zinc electrowinning. The main contents can be summarized as follows:1.The study of parameters optimizing and energy consumption in ZnSO4-H2SO4 system:After the technology conditions which influenced energy consumption in electrowinning process were analyzed synthetically, some contents were researched as follows:(1) the effect of the zinc sulfate and sulfuric acid concentration on the electrolyte density at different temperatures; (2) the effect of the zinc sulfate and sulfuric acid concentration on the electrical conductivity at different temperatures; (3) the effect of the zinc sulfate and sulfuric acid concentration on the cell voltage in electrowinning process; (4) the effect of the zinc sulfate and sulfuric acid concentration on the current efficiency in electrowinning process; (5) the effect of the zinc sulfate and sulfuric acid concentration on the energy consumption during electrowinning process. Regression analysis method was used to analyze the experimental date and the regression equations were deduced variational laws among each parameter based on test.. These equations can help us to analyze some practical questions of zinc electrowinning, and provide definite guidance for the use of status of improving electrical power and optimizing technical condition in hydrometallurgy of zinc.2.The study of effect of impurities on zinc electrowinning in ZnSO4-H2SO4 system:There are more than 20 kinds of impurities in zinc sulphate electrolyte, and Co, Ni, As, Sb, Ge are the main factors effecting the zinc product surface quality and current efficiency. We adopted the electrochemical methods to research the effects of Co, Ni, As, Sb, Ge impurities on zinc electrowinning in the experimental study. Through investigating above mentioned five impurities effects of transient and steady cathodic polarization curves from one dimension (on impurity) to five dimensions in different concentrations and temperatures. Through measuring data from polarization curv found e and calculating dynamic parameters according to Tafel and Butel-Volmer formulas we the electrons transferring number. It found that the concentration of Co>6mg/L, Ni>14mg/L, As>6mg/L, Sb≥1mg/L, and Ge≥lmg/L had appreciable impact, Co and Ni had minimal impact, Sb and Ge has more impact on zinc electrowinning. The three-stage purifying technology was put forward through experiments, which could actualize deeply deprivated.3. The study of effect of additives on the zinc electrowinning in ZnSO4-H2SO4 system:This text testing over ten reagents such as glutin, DBS and thiourea, which influenced on surface quality of zinc as additives. Optimize some additives which are good effect to we had more thorough research in mechanism of action through photos. The experiments revealed that glutin was absolutely necessarily in deposition process of zinc, compare single additive; compounded additive could make more ideal effect. Ideal additive could enhancement surface quality of zinc、increase current efficiency、economy cost obviously, additive could also depression return-dissolution phenomenon, had some value in industry.4. The study of effect of magnesium on zinc electrowinning:Mg2+which was more negative than zinc was not removed when the low concentration of Mg2+ had no effect on electrowinning process. But magnesium salt increased continuously in the hydrometallurgy system, it makes the density, viscosity and resistivity of the electrowinning solution increased when it reaches saturated concentration, which leaded to the resistance, the current efficiency and the energy consumption increasing. It was studied that the effects of Mg2+concentration on the density, viscosity and resistivity of electrowinning solution, and the current efficiency and energy consumption at different temperatures in this paper. And some experimental data were provided, which could be useful for hydrometallurgy factory and the correlation technological personnel.5. The study of the reaction kinetics model about zinc electrowinning with magnesium ion:the reaction kinetics model about zinc electrowinning in the zinc current sulfate solution with magnesium was presented in this paper. Density functional theory based on first principle and CASTEP quantization tools were used to demonstrate above model in theory.Some specific measures of energy conservation in zinc electrowinning were put forward through studing technology. The contents are listed as follows:(1)selecting optimized parameter system. When experimental condutions were certain(the current density was 527A/m2, temperature was 40℃, the dosage of glutin was 10mg/L, the period was 24h), the Zn2+concentration was 52g/L, the H2SO4 concentration was 134g/L, the energy consumption was the minimum value, which was 2961.344kW·h/tzinc.(2) Carrying through three-stage deeply purifying. Comparing with traditional purifying technology, the current efficiency was observed to increase 5%, and energy consumption to decrease 150kW-h/t using deeply purifying solution after electrowinning 48h. (3) Adding combined additives into electrolyte. It was thiourea and glutin, the dosage of thiourea was 20mg/L, the dosage of glutin was 15mg/L. after adding combined additives, the current efficiency was observed to increase 3%, and energy consumption to decrease 150kW·h/t, and the effect of combined additives was more evident when the period of electrowinning was more than 48h.The main innovation points:(1) The effects of the temperature, H2SO4 and Zn2+concentration on electrolyte density, electrical conductivity, the cell voltage and the current efficiency were studied, and the regression equation about the effect of electrowinning parameters on energy consumption was built up, which has directive significance for the actual production of zinc electrowinning.(2) Three-stage deeply purifying technology was put forward through systematically studying the effects of impurities on zinc electrowinning. Using this purifying technology the energy consumption could be decreased 150kWh/t. and the mechanism of hydrogen evolution about zinc electrowinning was researched.(3) The combined additives were obtained through studying the effects of single additive on zinc electrowinning, which were thiourea and glutin. Adding combined additives the energy consumption could be decreased 150kWh/t in zinc electrowinning.(4) Magnesium on the effect of zinc electrowinning was first researched, and got the reaction mechanism of zinc sulphate electrolyte with magnesium.更多还原