【作者】 杨声海；

【导师】 唐谟堂；

【作者基本信息】 中南大学 ， 有色金属冶金， 2003， 博士

【摘要】 本文针对目前氟、氯、铁等杂质元素高的氧化锌物料、氧化锌矿常规方法难以处理以及无汞合金锌粉用高纯锌必须由0号锌用真空蒸馏或精馏法生产的问题。首次在Zn（Ⅱ）-NH_3-NH₄Cl-H₂O体系中,直接由复杂的氧化锌物料和锌焙砂生产高纯锌。对Zn（Ⅱ）-NH_3- NH₄Cl-H₂O体系计算并验证了浸出过程热力学数据、绘制了净化过程电位-pH图、确定了电积锌时阴阳极的电化学反应动力学方程、最佳电解工艺条件以及添加剂对阴极锌形貌与晶体生长方向的影响,并把基础理论用于指导处理锌焙砂与炼铅炉渣烟化炉氧化锌烟灰生产高纯锌的实践,进行了实验室小型试验和100t/a的半工业性试验,均获得成功。根据同时平衡原理和溶液电中性原理,进行了Zn（Ⅱ）-NH_3- NH₄Cl-H₂O体系热力学计算,绘制出ZnO在NH_3-NH₄Cl溶液中的溶解度图。揭示了体系中锌的溶解性能及高溶解度区域,发现ZnO在NH_3-NH₄Cl水溶液中的溶解度比在同浓度的NH（3-）（NH4）2SO4或NH_3-（NH₄）₂CO₃水溶液中溶解度要大。在[NH₃]/[NH₄Cl]<1时,锌平衡浓度随氨浓度的上升而迅速升高,但到[NH₃]/[NH₄Cl]>1后,几乎不再上升。在NH4Cl 5mol/L的条件下,随氨浓度的增加锌的配合物由ZnCl_i^2-i占优势逐渐转变成几乎全部为Zn（NH₃）₄²⁺形式存在。ZnO在NH_3-NH₄Cl溶液中的溶解度验证实验表明,在不同的氨和铵浓度下,锌平衡浓度计算值与实际测定值的相对偏差的绝对平均值为11.37%。在浸出过程热力学计算的基础上,根据各杂质元素的精选配合物常数,计算出E_{Men /Me}-pH关系,绘制了Zn（Ⅱ）-NH_3-NH₄Cl-H₂O体系净化过程的E-pH图。发现了即使溶液中杂质元素浓度Meⁿ⁺<10^-6mol/L（Me表示Cu、Ni、Pb、Co）的情况下,E₍(Cu²⁺/Cu)、E_Ni²⁺/Ni、E_Pb²⁺/Pb及E_Co²⁺/Co与E_Zn²⁺/Zn的差均大于0.3v,因此锌粉可以很彻底的置换它们,而E_Cu⁺/Cu与E_Zn²⁺/Zn相差较小,因此置换前应尽量使铜以Cu²⁺形式存在。E_Cd²⁺/Cd、E_Co²⁺/Co与E_H⁺/H2比较接近,在常温净化的情况下,不会发生酸法炼锌过程中锌粉置换时镉反溶现象。进行了Zn （Ⅱ）-NH_3-NH₄Cl-H₂O系电积过程阳极反应的理论分析和实验验证,确定了该体系阳极反应析出氮气。用稳态极化法研究了Zn（Ⅱ）-NH_3-NH₄Cl-H₂O体系电积过程中阳极与阴极反应电极过程动更多还原

【Abstract】 Zinc oxide raw materials and zinc oxide ores, containing high fluorine, chloride and iron, can ’t be treated to produce electrowinned zinc by routine process. High-purity zinc using in non-mercury zinc powders is prepared only by using vacuum distillation or rectify process from zinc of the zero grade. In this article treating complex zinc oxide materials and preparing high-purity zinc are the primary objects of this study. A new process of preparing high-purity zinc directly from complex zinc oxide materials or zinc calcine was invented. The contents in this study include thermodynamic calculating, plotting potential-pH diagram of purification process, determining electrochemical kinetics of cathode reactions and anode reactions, effecting of additives on morphology and crystallographic orientations of electrowinned zinc in the system of Zn（II）-NH_3-NH₄Cl-H₂O, successfully applying basic theory to treat zinc calcine and zinc fume dusts from slags of smelting lead. According to the principles of simultaneous equilibrium and aqueous electronic charge neutrality, the thermodynamic data in the system of Zn（II）-NH_3-NH₄Cl-H₂O have been calculated and the solubility figures of ZnO in the system have been plotted. The solubility regular and high solubility areas of zinc oxide were discovered and this system has higher zinc solubility than ammoniacal ammonium sulfate system and ammoniacal ammonium carbonate system at same concentration. When ratio of ammonia concentration to ammonium chloride concentration is lower than 1/1, equilibrium solubility of zinc is almost proportionate to ammonia concentration. But when the ratio is larger than 1, the solubility almost not increases. When ammonium chloride concentration is constant, the dominated species of zinc are changed from ZnCl_i^2-i to Zn（NH₃）₄²⁺ with the increasing of ammonia concentration. The absolute average error between experimental values and theoretically calculated values of zinc equilibrium concentration is 11.37% in ammoniacal ammonium chloride solution. According to the thermodynamic calculation and the critical stability constants of impurities, relationships between potential and pH values have been calculated out and potential-pH figures have been plotted in the system of Men+-NH_3-NH₄Cl-H₂O. When Men+ concentration (Meⁿ⁺ representing Cu²⁺, Cu⁺, Pb²⁺, Ni²⁺, Cd²⁺, Co²⁺) is 10^-6mol/L, the subtractive values between E_Me²⁺/Me(Meⁿ⁺ representing Cu²⁺, Pb²⁺, Ni²⁺, Co²⁺) and E_Zn²⁺/Zn are higher than 0.3 volt. So impurities of Cu²⁺, Pb²⁺, Ni2+, Co2+ can be cemented completely. The value between ECu /Cu+and EZn 2 /Zn+ is small, so Cu+ must be oxidized to Cu2+ before cemented. The difference ofEZn 2 /Zn+andECd 2 /Cd+,EC o 2 /Co+ is small, cemented cadmium and cobalt aren’t resolved at room temperature in the system of Zn（II）-NH3-NH4Cl -H2O but they are resolved at high temperature in system of ZnSO4-H2O. Anodic reactions of electrowinning zinc, producing nitrogen, were analyzed theoretically and confirmed by experiments in the system of Zn （II）-NH3-NH4Cl-H2O. Electrochemical kinetics of cathode reactions and anode reactions were studied by using potentiostate. The electrochemical kinetics equation of anodic reactions was determined as follow. i 3.066 10 5 F [C l]1 .056 exp（ 40171）RT阳 = × × ?? The electrochemical kinetics equation of cathodal reactions was determined as follow. i阴 = 0.065 × F [ Zn 2 +]2 .157 exp（ ?10R9T50） The effects of various additives alone or multiply on cathodal linear polarization and cyclic voltammogram were investigated by using methods of scanning potentiostate and cyclic voltammeter. Cyclic voltammograms has been measured at stirring. We can conclude that glue stone absorbed on the cathodal surface affects on preventing cathodal electrochemistry reactions, not on the transfer velocity of zinc ions. We can conclude that T-B affects on preventing the transfer velocity of zinc ions for it is a strong cation and transfers with zinc-ammonia complexes. Zinc-T-C complex is easier to form than zinc-ammonia complex, which can largely increase transfer velocity. The effects of zinc concentration, electrode space, current density, temperature and additives（such as glue, T-B, T-C） alone or multiply on electroreduction Zn2+ ion have been studied. On the base of above experiments, the optimum conditions are as follows: zinc concentration more than 15g/L, electrode space 3cm, current density 400A/m2, temperature 40℃, glue stone 0.1g/L, T-B 0.1g/L, T-C more than 2mL/L, respectively. On the base of theoretical studies, a new process of preparing high-purity zinc directly from zinc calcine and complex zinc oxide fume dusts of smelting lead has been explored successfully in Zn（II）-NH3-NH4Cl-H2O system. After mini-experiment and expanded experiment in laboratory, the principle flowchart and the operational conditions were determined. The zinc content in the eletrowinned zinc is more than 99.999%, and the contents of impurities, such as Cu, Cd, Co, Ni, Fe, As, Sb, are all lower than 0.0001% respectively, but lead is lower than0.0003%. The leaching rate of zinc is more than 96% when treating zinc oxide fume dusts from slags of smelting lead and more than 91% when treating zinc calcine. Electrobath voltage and power consumption are 3.0 volt and range from 2500 to 2700kWh/t zinc respectively. This process can save 400 to 600 kWh per tone zinc in contrast with regular method. Semi-industrial experiments using zinc calcine as raw material have been accomplished. The expected objects were obtained and the data of designing factory were acquired. Leaching rate, electrowinning process and cathodal zinc quality are not affected by cycle using spent electrolyzed solution（after 8 experiments）. In the electrowinned zinc contents of impurities are as following, Cu, As, Sb, Fe less than 0.0001%, Co, Ni less than 0.0002%, Cd less than 0.0005% and Pb less than 0.0010% respectively, which suits to produce non-mercury and non-lead zinc powders. Non-mercury zinc powders have been pulverized from electrowinned zinc. The zinc powders give off less gas than model 004/68 prepared by Shanghai Bailuoda Metal Ltd. Co.. Direct and total recovery rate of zinc is about 87% and 100% respectively. The consumption of additive T-C, calcine, liquid ammonia, zinc powders and power is 0.0375t, 1.134t, 0.53t, 0.060t, less than 3000kWh per tone of zinc respectively.更多还原