电解锌液中铅基合金阳极腐蚀行为的交流阻抗分析

为研究铅基合金在电解锌液中的腐蚀过程,利用电化学交流阻抗谱(EIS)和Zsimp-Win软件拟合研究了铅及其合金等4种电极在电解锌液中自腐蚀电位下的腐蚀行为。结果表明:Pb-Ag(0.30%)-Sb(0.2%)合金的耐蚀性远大于纯Pb,Pb-Ag(0.30%)和Pb-Ag(0.75%)合金;铅基合金的腐蚀行为受电极电位以及疏松多孔的腐蚀产物的表面覆盖度2个变量的影响,腐蚀机理是腐蚀产物的覆盖及阴极反应被抑制;Ag和Sb的加入不仅细化和提高了合金的颗粒及硬度,也细化了腐蚀产物层的颗粒;在电解锌时,铅基合金阳极中的铅易反溶进入溶液,进而在阴极析出影响阴极锌产品质量。

锰(Ⅲ)-磷酸分光光度法测定电解锌液中的锰

测定电解锌液中锰的含量有几种常用方法,经反复实验,得出锰(Ⅲ)-磷酸分光光度法,更适合于电解锌液中锰的测定。本文对实验条件进行全面的研究,并确定减少取样量,提高系列标准曲线浓度,确定了最佳实验条件。该方法简便、快速、经济、廉价,而且流程短,易于掌握。

锌电解体系中电解新液除氟研究

结合炼锌企业的需求,对电解新液进行了一系列改性沸石脱氟试验研究。改性沸石脱氟操作简单,不对溶液中的锌造成不利影响,不会引入有害杂质;同等条件下,改性沸石脱氟效果优于生石灰和针铁矿脱氟。

氢化物发生-原子吸收光谱法快速测定锌电解料液中痕量砷

在盐酸介质中 ,As( )用碘化钾和抗坏血酸还原成 As( )后 ,再与强还原剂硼氢化钾反应生成气态氢化砷。氢化砷用氮载气送入原子化系统原子化后进行测定。砷的最大吸收波长为1 93.7nm,在 0 .5～ 50 ng·ml-1范围内 ,砷浓度与吸光度呈线性关系 ,检出限为 3.4× 1 0 -9mol·L-1。方法毋需预处理直接用于锌电解料液中微量和痕量砷的测定 。

苯芴酮分光光度法测定锌电解液中的锡

在含有酒石酸（200g／L）的硫酸溶液中，锡（Ⅳ）与苯芴酮生成有色络合物，可采用分光光度法直接测定电解锌液中的锡。此络合物在510nm波长处有最大吸收峰，锡（Ⅳ）含量为0．2～2．0mg／L，符合朗伯——比耳定律。该方法灵敏度高，快速准确，重现性好。适用于锌电解液中锡的测定。

湿法炼锌电解阳极泥综合利用及Mn^(2+)的控制

国内湿法炼锌企业通常将槽内锌阳极泥与平板锌阳极泥直接回用于浸出系统,但此过程中的电解锌液Mn^(2+)浓度控制难度大。本文创造性提出了电解锌液Mn^(2+)浓度小于4 g/L时,平板锌阳极泥与锌精矿配料,通过焙烧高温还原MnO_(2)为低价锰,降低阳极泥氧化效率,提高电解锌液Mn^(2+)浓度。操作参数:阳极泥与锌精矿配料质量比约1∶100、沸腾层温度910~950℃、炉底温度300~330℃;电解锌液Mn^(2+)浓度不小于4 g/L时,平板锌阳极泥经球磨、浆化后回用于浸出系统,粒度控制在0.074 mm左右,氧化效率达到91%以上。不同条件下的回用方式,不仅实现了有价金属的综合回收利用,也利于电解锌液Mn^(2+)浓度的及时调整,为生产稳定运行奠定基础。

镍—锌双盐铝阳极氧化膜电解着色工艺研究

研究了镍—锌双盐铝阳极氧化膜电解着色工艺。探明了着色液中各组分的作用和电解参数对着色效果的影响,从而得出最佳工艺。对着色液性能进行了测定,结果表明镍—锌双盐体系的分散能力明显优于纯镍盐溶液,与纯亚锡盐电解着色液的分散能力相当。该体系的抗杂质干扰能力明显优于纯镍盐溶液。实验结果表明,在该体系中电解着色铝氧化膜层的耐蚀性、耐磨性及耐外紫光照射性能良好。

Effect of MnO_4^- and silver content on electrochemical behaviour of Pb-Ag alloy anodes during potential decay periods

The effect of MnO4- and silver content on electrochemical behaviour of five commercial Pb-Ag alloy anodes was studied in acid zinc sulphate electrolyte with and without MnO4- ions at 38 °C during potential decay periods. When the anodes were immersed into acid zinc sulphate electrolyte without MnO4- ions, the Pb-0.72%Ag anode entered complete passivation state in the shortest time among the five anodes, followed by anodes Pb-0.67%Ag, Pb-0.60%Ag, Pb-0.58%Ag and Pb-0.29%Ag-0.1%Ca by measurement of open circuit potential. During immersion of the anodes, MnO4 ions accelerated the passivation and increased the corrosion current density of the anodes. After immersion in zinc electrolyte with MnO4-, the anode Pb-0.72%Ag had the best corrosion resistance, followed by anodes Pb-0.67%Ag, Pb-0.60%Ag, then the close anodes Pb-0.58%Ag and Pb-0.29%Ag-0.1%Ca by the electrochemical impedance spectroscopy （EIS） analysis.

搅拌机节能改造及实践

本文结合生产实例 ,对因设计缺陷造成严重过负荷的多台 70m3 非标搅拌机故障进行分析比较 ,在不改变原机结构及性能前提下 ,采取简单易行措施对设备进行改造 。

Simultaneous determination of trace Cu^(2+), Cd^(2+), Ni^(2+) and Co^(2+) in zinc electrolytes by oscillopolarographic second derivative waves

Simultaneous determination of impurity metal ions in high concentration zinc solution is very important for zinc hydrometallurgy,and the purpose is to establish a method for determining the trace Cu^2+,Cd^2+,Ni^2+and Co^2+in zinc electrolytes at the same time using the second derivative waves of single sweep oscillopolarography.Factors affecting the derivative waves of the ions were researched in a medium of dimethylglyoxime(DMG)-sodium citrate-sodium tetraborate.The results indicated that the interferences of a high concentration of Zn^2+and most other coexisting ions on the determination can be eliminated;when the Cu^2+,Cd^2+,Ni^2+and Co^2+are in the ranges of1×10^-7-3×10^-4,6×10^-7-2×10^-4,2×10^-8-1×10^-5and1×10^-8-3×10^-5mol/L,respectively,the relationships between the peak currents of the second derivative waves and the concentrations are linear;the detection limits to determine the Cu^2+,Cd^2+,Ni^2+and Co^2+are8×10^-8,2×10^-7,6×10^-9and4×10^-9mol/L,respectively.Without any sample pretreatment,the method was used to directly determine the trace Cu^2+,Cd^2+,Ni^2+and Co^2+in actual zinc electrolytes with satisfactory results.The method is simple,sensitive and rapid.

Statistical evaluation and optimization of zinc electrolyte hot purification process by Taguchi method

The neutral zinc sulfate solution obtained from hydrometallurgical process of Angouran zinc concentrate has cadmium, nickel and cobalt impurities, that must be purified before electrowinning. Therefore, cadmium and nickel are usually cemented out by addition of zinc dust and remained nickel and cobalt cemented out at second stage with zinc powder and arsenic trioxide. In this research, a new approach is described for determination of effective parameters and optimization of zinc electrolyte hot purification process using statistical design of experiments. The Taguchi method based on orthogonal array design（OAD） has been used to arrange the experimental runs. The experimental conditions involved in the work are as follows： the temperature range of 70-90 ℃ for reaction temperature（T）, 30-90 min for reaction time（t）, 2-4 g/L for zinc powder mass concentration（M）, one to five series for zinc dust particle size distributions（S1-S5）, and 0.1-0.5 g/L（C） for arsenic trioxide mass concentration. Optimum conditions for hot purification obtained in this work are T4（85 ℃）, t4=75 min, M4=3.5 g/L, S4（Serie 4）, and C2=0.2 g/L.

Selective determination of trace cobalt in zinc electrolytes by second-derivative catalytic polarography

We report herein a highly selective method for directly determining the trace Co^2+in highly concentrated zinc electrolyte.This novel method is based on a second derivative wave of catalytic adsorptive polarography generated by complexing Co^2+with dimethylglyoxime and nitrite onto a dropping mercury electrode.By employing a medium with NH3-NH4Cl buffer,DMG and NaNO2 during determining the trace Co^2+,any interferences of highly concentrated Zn^2+and other coexisting metal ions in the electrolyte are completely eliminated due to the selective masking effect of EDTA.When the concentration of Co^2+is within 1.0×10^–10–3.2×10^–7 mol/L range,it shows a good linear relationship with the current peak.Detection limit is 1.0×10^–11 mol/L,and RSD≤2.7%for six successive assays.We have compared the efficiency of the current method to that obtained by cobalt nitroso-R-salt spectrophotometry,and the absolute values of relative deviations are≤4.2%.The method developed and described herein has been successfully employed in determining the trace Co2+in actual zinc electrolyte.

Stability of [BMIM]HSO_4 for using as additive during zinc electrowinning from acidic sulfate solution

The stability of ionic liquid additive 1-butyl-3-methylimidazolium hydrogen sulfate （[BMIM]HSO4） during zinc electrowinning from acidic sulfate solution was investigated by cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. Compared with the traditional industrial additives, gelatine and gum arabic, [BMIM]HSO4 has more excellent chemical and thermal stabilities. The inhibition effects of gelatine and gum arabic on the zinc electrocrystallization are observed to markedly weaken due to their part degradation after 12 h longtime successive electrolysis and high temperature （90 ℃） treatments. In contrast, the activity of [BMIM]HSO4 is practically unaffected after 24 h longtime successive electrolysis and high temperature treatments. These results are corroborated with the corresponding morphological analysis of the cathodic deposits.

Oxygen pressure acid leaching of Gacun complex Cu concentrates

The treatment of the Gacun complex Cu concentrate with high contents of Pb,Zn,Ag,etc by oxygen pressure acid leaching was studied.It is unusual that tetrahedrite,whose treatment was rarely studied,is the primary copper mineral of the concentrates.Most of silver also occurs in the mineral.The optimum operating parameters of oxygen pressure acid leaching were established by conditional tests.Pilot scale test was carried out under the parameters,and the leaching rates of copper and zinc are as high as 97.10% and 89.83% while lead and silver are transformed into sulfate and sulfide respectively and stay in leaching residue.The copper and zinc in lixivium were reclaimed by extraction-electrowinning and purification-electrowinning,respectively,and the lead and silver in the residue were reclaimed separately by chloride leaching and thiourea leaching.The extraction rate of copper achieves 96%,and the leaching rates of lead and silver reach 90% and 95%,respectively.

Effects of Electrolyte Concentration, Temperature, Flow Velocity and Current Density on Zn Deposit Morphology

The most critical disadvantages of the Zn-air flow battery system are corrosion of the zinc, which appears as a high self-discharge current density and a short cycle life due to the non-uniform, dendritic, zinc electrodeposition that can lead to internal short-circuit. In our efforts to find a dendrite-free Zn electrodeposition which can be utilized in the Zn-air flow battery, the surface morphology of the electrolytic Zn deposits on a polished polymer carbon composite anode in alkaline, additive-free solutions was studied. Experiments were carried out with 0.1 M, 0.2 M and 0.5 M zincate concentrations in 8 M KOH. The effects of different working conditions such as： elevated temperatures, different current densities and different flow velocities, on current efficiency and dendrite formation were investigated. Specially designed test flow-cell with a central transparent window was employed. The highest Coulombic efficiencies of 80%-93% were found for 0.5 M ZnO in 8 M KOH, at increased temperatures （50-70 ℃）, current densities of up to 100 mA.cm2 and linear electrolyte flow velocities higher than 6.7 cm.s1.

Pt/Zn heterostructure as efficient air-electrocatalyst for long-life neutral Zn-air batteries

Neutral Zn-air batteries(ZABs) have attracted much attention due to the enhanced lifespan and stability.However, their development is suppressed by the poor catalytic properties of the air-electrocatalysts for oxygen reduction reaction(ORR) and oxygen evolution reaction(OER). Hence,the exploration of highly efficient electrocatalysts for neutral ZABs is critical. Herein, we designed an economical heterostructure of Pt nanoparticle-modified Zn nanoplates(Pt/Zn NPs). Compared with commercial Pt/C electrocatalyst, our Pt/Zn heterostructure exhibits comparable catalytic properties and ultrahigh stability in neutral media. The heterostructure can reduce the dosage of Pt and offer sufficient active sites,resulting in enhanced catalytic properties for ORR/OER in neutral media. When applied to neutral ZABs as air cathode,our heterostructure exhibits a high power density of 45 mW cm^(-2) and excellent stability of more than 850 cycles with negligible decay, making it the most efficient and robust one in neutral electrolyte. This approach opens a new avenue to strategically design catalysts with high activity for neutral ZABs, rendering them potential in portable and wearable electronic devices.