Computerized scaled cells to study the effect of additive ratios and concentrations on nodulation during copper electrorefining

Scaled copper electrorefining cells were designed, built and computerized to simulate as closely as possible industrial conditions at three Canadian copper refineries. The industrial dimensions of Falconbridge, Kidd Metallurgical Division, were considered while designing scaled cells. Anode width to cell width ratio, anode width to cathode width ratio, anodic surface to cathodic surface ratio, as well as electrolyte volume to cathodic surface ratio, which was about 60 L m^–2, were consistent with Kidd's industrial ratios. However, the cell design also allowed simulation of INCO's Copper Cliff Copper Refinery (CCCR) or Noranda's Canadian Copper Refinery (CCR). Electrorefining cells were 135.0 cm deep by 14.7 cm wide. Electrolyte flow rate was parallel to the electrodes. Electrolyte was circulated from the lower part of the electrorefining cells to the top where there was an overflow going to the electrowinning circuit. The equipment was computer controlled using Labview software. Experiments were conducted using this scaled electrorefining set-up to evaluate the effect of various ratios and concentrations of additives on nodulation during copper electrorefining under high current densities. Cathodic polarization curves, SEM micrographs, porosity analyses and copper grain analyses were used to characterize the cathodes produced.     

Influence of magnetic field and gravity on the morphology of zinc fractal electrodeposits

We present a comprehensive study of growth of zinc fractal electrodeposits in a flat electrochemical cell considering the effects of applied voltage, electrode shape and thickness, ion concentration and applied magnetic field for both concentric and parallel electrode geometries. The effect of gravity is also considered in vertical cells. ‘Phase diagrams’ set out the variety of morphologies achievable at different voltages and concentrations for both electrode geometries. Electron microscope analysis indicates that the deposits are built from individual micron-sized crystallites. The system is modelled numerically using a number of modifications to the diffusion-limited aggregation (DLA) model to introduce migration and convection. Experimentally observed morphologies are reproduced numerically for horizontal and vertical, concentric and parallel electrode cells. Each occupied numerical site represents not an individual atom, but the point of nucleation and growth of an individual zinc crystallite containing ∼10¹⁰ atoms.     

焙烧酸浸渣中铜的形态对铜、金浸出率的影响

以某黄金冶炼厂含铜金精矿为研究对象,采用铜化学物相分析及浸出方法研究了焙烧?酸浸?氰化工艺处理含铜金精矿过程中焙烧酸浸渣中铜形态对铜、金浸出率的影响. 结果表明,含铜金精矿焙烧酸浸及氰化浸出时,铜形态对铜、金浸出率有显著影响,当酸浸渣中氰化易溶铜(氧化铜、次生硫化铜)含量大于0.10%时,金浸出率降低. 以原生硫化铜矿为主的含铜金精矿,适当提高焙烧温度、延长焙烧时间、增加初始酸浸酸度可有效降低酸浸渣中氰化易溶铜含量,提高铜浸出率,减弱其对金浸出率的影响.     

脉冲铜沉积层织构及形貌的研究

采用脉冲电沉积工艺制备了铜沉积层,研究了电流密度、脉冲频率和占空比对铜镀层织构的影响。利用X射线衍射仪(XRD)和扫描电子显微镜(SEM)分析了铜镀层的织构和形貌。实验结果表明,低电流密度下为(200)晶面择优取向,高电流密度下为(111)晶面择优取向,频率越高则择优取向越强。低频脉冲下制备的沉积层平整致密。     

水质对镀铜层表面质量的影响

镀层麻点是电镀加工的常见质量问题。铜合金眼镜架经预镀铜和光亮酸铜工艺处理,工序间普遍采用自来水水洗?分别在含有无机盐、有机物、游离性余氯的洗涤水中,试验各因素对预镀铜层表面质量的影响结果表明,洗涤水中游离性余氯是形成预镀铜层麻点的主要因素,产生麻点的游离性余氯含量以0.4mg／1。为界限值,由此提出控制预镀铜层麻点的有效措施     

我国回转窑水泥不同粉磨工艺颗粒形貌剖析

利用电子显微镜及专用的计算机软件等方法，对我国目前大中型水泥企业不同粉磨工艺下水泥颗粒形貌状况进行了研究分析。研究结果表明，我国不同粉磨工艺下水泥颗粒形貌存在较大差别，提高磨机研磨功能有利于改善水泥颗粒形貌。     

用扫描隧道显微镜研究铜表面苯并三氮唑吸附膜的结构形态

It is observed by scanning tunneling microscopy (STM) that the adsorbed Benzotriazole (BTA) on copper is long in shape and has an irregular rectangle.The growth of BTA on copper is in the from of polymeric chain and mainly in one dimension rather than two dimensions.The copper surface covered by BTA becomes flatter,smoother and the roughness was smaller than that of bare copper,so the corrosion is largely decreased.However,many grooves can be seen between BTA polymeric chains in which corrosion may exist to a degrees.     

Effect of sulphuric acid and copper sulphate concentrations on the morphology of silver deposit in the cementation process

The silver ion cementation on copper was investigated in the presence or absence of oxygen in solutions containing 1.85 × 10⁻⁴ M Ag⁺ at 25 °C. The influence of sulphuric acid and copper sulphate concentration (0.005-0.5 M) on the silver cement morphology was studied in details and results were linked with the previously determined kinetics data of the process. The morphology of silver deposit was found to be independent of the presence of oxygen in the system as well as the sulphuric acid concentration. Contrary, the concentration of copper sulphate strongly influenced the morphology of silver deposit. At the beginning of the cementation process silver covers uniformly the copper surface. Afterwards, a growth of dendrites is initiated on preferential parts of the surface. The growing dendrite behaves as cathodic sites, with relatively huge surface area and promotes the creation of anodic sites in a close neighbourhood. Finally, the anodic site encloses the dendrite island and develops its area inward the copper material. Copper ions at low concentration modified slightly silver dendrites but the increase in concentration up to 0.5 M Cu²⁺ leads to completely disappearance of dendrites from the surface. The lack of dendrites on the surface is a result of the competitive process that consumes additional silver ions, occurring in the bulk of the solution. The morphology of silver deposit cemented in the deoxygenated solution containing 0.5 M H₂SO₄ + 0.5 M CuSO₄ depends strongly on the mechanism of the process.     

铜渣基草酸盐水泥的制备及其性能

以铜渣和草酸为原料,按一定比例混合,通过酸碱反应制备铜渣基草酸盐水泥,考察了铜渣与草酸质量比(CS/OA)、水灰质量比(W/C)、缓凝剂种类及掺量对所制水泥力学性能和凝结时间的影响,用扫描电镜和X射线粉末衍射仪分析了水泥的微观形貌和物相组成。结果表明,随质量比CS/OA和W/C增加,水泥的抗压强度呈先增大后减小的趋势,凝结时间随CS/OA增大而减小,随W/C增大而增大。硼砂和三聚磷酸钠对水泥的抗压强度影响较大,随其掺量增加,水泥的力学性能降低,适量的硼酸可提高水泥的抗压强度,且具有较好的缓凝效果,可将硼酸作为较佳缓凝剂。当质量比CS/OA=4和W/C=0.16~0.17、硼酸掺量为2.5wt%时,材料性能最优,养护28 d抗压强度可达38.5 MPa,凝结时间为24 min。水泥主要水化产物是结构密实、结晶良好的柱形FeC2O4?2H2O,添加硼砂和三聚磷酸钠会使水泥出现孔隙,而硼酸会促进水化反应使水化产物结晶更优,且不会破坏水泥的密实度。     

Copper electrodeposition in sulphate solutions in the presence of benzotriazole

DC and pulse plating of copper in acidic sulphate solutions containing benzotriazole (BTA) has been studied. When BTA is the only additive present, it generally has a stronger effect than the plating mode and significantly enhances deposit morphology and surface brightness over that produced in additive-free solutions. XPS and voltammetry analyses indicate that BTA is present at the surface of the deposit, but not through the entire coating, and does not become depleted within the solution over the course of plating. This may help explain why the initial surface smoothness and brightness is maintained as the coating grows beyond 5 μm thick. Plating mode does have a strong effect on deposit morphology under specific conditions. Pulse current plating at low frequency (50 Hz) and low duty cycle (20%) produces deposits with poorer quality than that obtained by DC plating. Pulse reverse plating yields very coarse and dull coatings when the frequency is low enough for metal dissolution to occur during the reverse time. Regardless of the plating mode, the addition of Cl⁻ eliminates most of the beneficial effects of BTA and leads to very rough and dull deposits. The observed effects are discussed in light of previous research on the electrodeposition and corrosion of the Cu–BTA and Cu–BTA–Cl systems.     

不同物料对水泥颗粒分布及水泥性能的影响

模拟水泥生产实际,对不同组分单掺、双掺和复掺情况下混合粉磨对水泥颗粒分布及水泥性能的影响进行了试验研究。结果表明:(1)粉煤灰、石灰石部分替代矿渣后能够显著降低水泥的特征粒径和均匀性系数,促进水泥的整体粒度下降;(2)粉煤灰不能显著增加水泥中微粉含量,而石灰石可以显著增加水泥中微粉含量;(3)混合材料的复掺对于改善水泥颗粒分布的效果优于单掺或双掺。另外,不同物料混合粉磨对水泥性能的影响主要是由于水泥颗粒分布的拓宽、水泥中微粉含量的增加,提高了水泥颗粒的堆积密度造成。     

Examination of Portland cement paste hydrated in the presence of malic acid

When malic acid (MA) solutions are added to ordinary Portland cement (OPC), rapid heat evolution takes place, but the hydration is retarded considerably at all the MA concentrations. To understand the mechanism of retardation, UV-visible and IR spectral studies were made and the results have revealed that some interaction occurs between MA and certain constituents of OPC. X-ray diffraction (XRD) and thermogravimetric (TG)/differential thermal analysis (DTA) studies have proved the formation of a new reaction product due to interaction between MA and some of the mineral phases of Portland cement. The retardation of the hydration of Portland cement may be attributed to the formation of this new compound.     

Effects of current density on adhesion of copper electrodeposits to polyimide substrates

To provide protection, electrical conductivity, or a decorative finish, plastic components are often metallized by a three-step process: deposition of a catalytic palladium layer followed by electroless and electrolytic plating. In this paper we focused on determining the relationship between applied current density used to electrodeposit copper and adhesion of the metal to a polyimide substrate. To test a range of current densities on a single sample, we deposited a series of copper strips on a planar sheet of the polyimide material and electrodeposited copper in a modified Hull cell. From peel tests we found that strips subjected to higher current density adhered more strongly to the substrate. This experimental procedure should be generally applicable to other metal-polymer systems.     

辊压机粉磨水泥性能缺陷及其解决方案分析

辊压机终粉磨的工作效率高、能耗低,但其成品水泥由于颗粒级配不合理,颗粒形貌圆形度差,导致其需水量大,凝结太快,难以达到使用要求。分析了影响水泥施工需水量的各种因素,讨论了水泥需水量增加的后果,提出通过减小辊径,增加打散机或V形分级机,可对终粉磨成品性能有所改善;而采用辊压机加球磨机的二级粉磨系统,则充分利用了两种磨的各自优点,能获得高产、低耗和产品性能优的终合效果。     

Electrochemical investigations of copper behaviour in different cupric complex solutions: Voltammetric study

The electrochemical behaviour of copper has been investigated in different cupric complex solutions by cyclic voltammetry. In pyridinic and picolinic solutions the reduction of cupric complex occurred in two stages leading to Cu(I) and Cu(0), respectively. The electrodeposited copper is oxidized in two steps leading to Cu(I) and Cu(II) as in ammoniacal cupric complex solutions. In glycine, alanine, sulfamic acid and ethylenediamine solutions, the cuprous complex is an intermediate in the cupric complex reduction but it is not detected during the oxidation of the electrodeposited copper in these solutions. In EDTA and triethanolamine solutions, the cuprous complex is not observed. The rate of copper etching was determined in pyridinic and ammoniacal cupric solutions and was shown to be faster in ammoniacal cupric solutions than in the pyridinic solutions.     

不同助磨剂对水泥粉磨效率的影响

提高水泥粉磨细度的主要技术措施为改造磨机结构和掺加助磨剂。前者在提高水泥细度的同时将导致磨机产量明显降低,而后者能有效提高磨机的粉磨效率并改善水泥的某些性能,但不同助磨剂对不同的水泥具有一定的适应性。作者选用四种助磨剂（代号分别为T,M,D,C）对掺加不同混合材的立窑和回转窑水泥进行了粉磨试验研究,以寻求各种助磨剂的使用规律和应用效果。实验结果表明:掺加T和M后对各种水泥的助磨效果均优于D;T和M复合而成的C具有良好的助磨效果,且成本低得多,具有重要的实际应用价值;掺加助磨剂可显著提高普通水泥和火山灰水泥的粉磨效率,但对矿渣水泥的助磨效果不明显;混合材种类及掺入量相同时,助磨剂对回转窑水泥的助磨效果优于立窑水泥。     

Effect of nickel on copper anode passivation in a copper sulfate solution by electrochemical impedance spectroscopy

Electrochemical Impedance Spectroscopy (EIS) was applied on Cu-Ni samples passivated in a specially designed flat electrochemical cell which was heated at 60 °C. The electrolyte consisted of 160 g l⁻¹H₂SO₄, 40 g l⁻¹ Cu²⁺ and 0, 10, 20, 30 or 40 g l⁻¹ Ni²⁺ and the copper anodes contained nickel ranging from 0 w% to 10 w%. The oxygen content of the anodes and the electrolyte was also measured. An AC excitation signal of 10 mV and of 1mHz 100 MHz frequency was applied at the open circuit potential as well as at a passivation potential, the latter having been determined previously. The results indicate that nickel ion additions to the electrolyte increased the resistance of the electrolyte and altered the porosity, thickness and constituents of the passivation layer formed. The equivalent circuit models generated from the data acquired during the EIS experiments and the values for the electrical components were in the predicted range. The results are supported by supplementary XRD and SEM findings.     

The anodic dissolution of copper in hydrochloric acid solutions

The electrodissolution of copper in hydrochloric acid solutions at the rotating ring-disk electrode was found to be controlled by both mass transfer and reaction in the apparent-Tafel region in HCl concentrations of between 0.1 and 1.0 M. The proposed mechanism describes the adsorption of CuCl_ads on the corroding copper surface and the diffusion of CuCl⁻₂ from the copper surface. The reaction in the limiting-current region was found to be controlled by the diffusion of Cl⁻ to the copper surface through a porous CuCl layer that forms on the surface. The thickness of this porous layer is dependent on the stirring conditions, and independent of the Cl⁻ concentration. Cu²⁺ is also produced at the Cu surface during electrodissolution. A mechanism describing the formation of a porous film of CuCl on the surface, the diffusion of Cl⁻ through this film and the formation of Cu²⁺ has been proposed.     

Corrosion of cyanide copper deposits on zinc diecastings in acid solutions

The corrosion potential and morphology of copper films deposited from a cyanide solution on zinc diecast were studied in acid solutions similar to those employed in industry for the deposition of a second copper layer. Open circuit potential measurements and gravimetric methods were employed to determine the influence of the copper electrodeposition variables on the corrosion potential. The influence of variables such as the presence or absence of additives, the current density and the copper or cyanide concentrations were studied. The corrosion potential decreased with increasing copper film thickness. Less protection was obtained when a thin copper layer was electrodeposited from a solution without additives. Higher protection for the same thickness was obtained from a solution with high cyanide content. This result is related to the strong interaction between cyanides and the metal surface during the electrodeposition. A smooth surface structure was observed by SEM under these conditions.     

Electrochemical kinetic parameters for the cathodic deposition of copper from dilute aqueous acid sulfate solutions

The use of linear-sweep voltammetry and chronopotentiometry for the determination of kinetic parameters for the electrolytic recovery of copper from a simulated acid-copper electroplating waste solution was demonstrated. For the electrodeposition of copper from solutions of 0.007?0.008 mol/L CuSO₄ + 0.5 mol/L H2SO₄ at 25°, the recommended values of the transfer coefficient (α) and exchange current density (i₀) are α = 0.46±0.06 (95% confidence interval) and i₀ = 11±4 A/m². The close agreement between these values and the available literature values indicates the reliabilaity of the voltammetric and chronopotentiometric methods.