The corrosion of lead anodes in copper electrowinning

The steady-state corrosion rate of 0.4 pct As-10 pct Sb-Pb anodes in H₂SO₄ copper electro-winning electrolytes was studied. The corrosion rate increases markedly with increasing acid strength and current density, although the corrosion per pound of copper electrowon is affected only slightly by current density. Several ions such as Cu⁺², Mg⁺², Al⁺³, SiO₃ ^-2 and Na+ have no effect on the corrosion while Fe+S and Ni+2 ions have moderate inhibiting effects. Strong corrosion inhibition is brought about by introducing small amounts of Co*2 into the solution or by substituting a Ca-Pb alloy for the conventional antimonial lead anodes.     

Dissolution kinetics of copper sulphide anodes

Constant current and voltammetric experiments were carried out with synthetic and natural chalcocite and synthetic digenite anodes in a variety of electrolytes. Rapid dissolution of copper occurred at low potentials until limited by the rate at which copper could be transported from the reaction zone by diffusion through electrolyte held within the porous product layer. At this point, the potential rose sharply (galvanostatic) or the current began to fall (voltammetric) corresponding to the formation of elemental sulphur. Quantitative support for this mechanism was obtained using a simplified model of the pore diffusion process. The complexity of the solid-state reactions occurring in the anode product was revealed by a novel technique which enabled direct observation of the product profile during electrolysis.     

Metastable grain boundary segregation in copper containing tellurium

Evidence for metastable grain boundary segregation has been experimentally obtained in Cu alloyed with 25 to 100 ppm Te. The solution-treated material fractured in a ductile intergranular mode. After aging for a short time; i.e., one day at 540°C, the fracture is intergranular and is attributed to the observed intergranular segregation of Te. The magnitude of the tellurium segregation and its local nature are established using Auger electron spectroscopy. Further aging results in precipitation of a stable phase throughout the grains and grain boundary fracture no longer takes place.     

分铜液净化渣中回收碲

江西铜业集团公司贵溪冶炼厂一车间在处理铜阳极泥提取金银的同时,处理生产废水得到一种富含铋、锑、碲等有价金属的沉淀物——分铜液净化渣,其中有价金属价值在若干万元,随着贵冶铜产能的扩大,分铜液净化渣产出量将相应增大,其潜在价值将更大,本文介绍分铜液净化渣处理工艺流程,并确定最佳工艺条件。     

Quantitative mineralogical characterization of roasted Ni-Cu concentrates

The mineralogy of partially roasted Ni-Cu sulphide concentrates was evaluated. The chemical composition and phase quantification of calcine particles were determined by optical and electron microscopy, X-ray microanalysis, and image analysis.The results indicate that the calcine particles are at various stages of oxidation. Nine mineralogical phases have been identified and quantified. Excellent correlation of the elemental analytical value with that of the chemical analysis was obtained. The applicability of image analysis to quantify the oxidation process of Ni-Cu concentrates has been demonstrated.     

铜电积中铅钙锡阳极钝化层的管理

现代铜电解槽中最常用的阳极为铅钙锡合金阳极,在铜电积过程中,PbO_2(过氧化铅)层在阳极表面形成。这层PbO_2的重要性在于保护金属铅阳极不被酸腐蚀,以使析氧反应有一个合理的交换电流密度。然而,在非正常状况或者断电条件下,PbO_2的电化学行为会导致阳极退化,并且导致铜阴极含铅量过高,以及为清除槽底累积的阳极泥而频繁停工。当发生停电或电解槽需要清理而断电时,便会出现非正常状况。某些电解槽为上述情况配置了有限容量的备用整流器。本文描述了PbO_2层形成和损坏的机理,并且确定了维持阳极表面PbO_2层致密性所需要提供的最小电流密度。     

某含金银铜矿石工艺矿物学研究

对某含金、银、铜矿石的研究重点是查明矿石工艺性质,金矿物、银矿物及铜矿物在矿石中嵌存状态、嵌布粒度等工艺特性。同时,对金矿物、银矿物组成及超出显微镜分辨能力的次显微金、银采用扫描电镜进行系统研究。矿石的工艺矿物学研究为选矿工艺流程和条件试验的确定提供可靠数据,以期选矿试验金、银、铜获得理想的回收指标。     

从铜阳极泥综合渣中浸出碲的研究

采用氧化酸浸的方法从铜电解阳极泥处理过程中产生的综合渣中浸出碲.对氧化荆进行了选择,考察了氧化荆用量、残酸浓度和浸出时间对碲漫出率的影响,确定的最佳漫出条件为:浸出温度80℃、液固比10:1、每50 g物料氧化剂A用量为1 g、残酸浓度3.6mol/L、浸出时间5 h.在最佳浸出条件下,碲的浸出率达到90.09%,铜的浸出率为97.81%.     

Developments in anodes for pure copper electrowinning from solvent extraction produced electrolytes

The adoption of solvent extraction (SX) techniques in copper recovery flowsheets has resulted in the production of electrolytes from which extremely pure copper may be obtained directly by electrowinning. The necessity to use high acid content strip solutions however may result in attack of conventional lead anodes and therefore in cathode contamination by anode material. Extensive studies have been carried out to determine methods of preventing lead anode dissolution and various alternative lead and non-lead anode materials which are capable of operating under tankhouse conditions have been examined. Non-lead anode materials, which it has been suggested may replace conventional anodes, are described and the effect on capital and operating cost of installing and using higher cost non-lead anodes is examined in comparison with lower cost lead anode alternatives.     

低浓度铜阳极泥加压浸出液中银硒碲的分离

采用铜粉置换的方法从低浓度铜阳极泥加压浸出液中综合回收银、硒、碲、铜等有价金属。结果表明,控制置换反应温度分别为≤45℃、≤75℃、≥95℃时,可以分别得到以银为主的银渣、以硒为主的硒渣和含银硒很低的碲渣。当浸出液中碲浓度很低时,先采用铜粉分步置换银、硒,再结晶脱铜,脱铜母液用铜粉置换,碲置换率可达99%以上,碲置换渣含碲高达36%~43%。     

Corrosion and passivation behavior of noble metal coated anodes in copper electrowinning applications

The performance of platinum/iridium coated titanium anodes under electrolytic conditions typical of those encountered in copper electrowinning applications has been studied. The corrosion loss of coating totalled approximately 1.5 μg/A · h during normal operation with a preferential loss of platinum from the coating. Anode potentials were observed to increase with time and the onset of complete electrode degradation was accompanied by a large increase of anode potential together with a loss of coating by spalling. The mechanism of coating loss and anode degradation is discussed. Graduate Student, University of British Columbia, Department of Metallurgy     

高碲铜阳极泥湿法处理试验

贵溪冶炼厂铜阳极泥处理原设计采用国内某冶炼厂湿法工艺流程,但该流程不完全适应贵冶阳极泥变化情况,1987年7月建成投产后,生产比较被动.为完善阳极泥湿法处理工艺流程,1988年进行了联合攻关,经过试验摸索,终于获得了比较适合贵冶特性的高碲铜阳极泥湿法处理工艺流程,并已付诸于工业生产.本文着重介绍高碲铜阳极泥湿法处理的试验情况并对其工艺特点进行了探讨.     

Electrowinning copper from solvent extraction acid strip solution using Pb-Sb anodes

Copper electrowinning from solvent extraction acid strip solutions was studied as a part of a more comprehensive laboratory investigation on development of a process for treating native copper ores by ammoniacal leaching-solvent extraction-electrowinning methods. Because initial electrowinning tests resulted in poor quality copper cathodes, a study was undertaken to determine the conditions necessary for producing high-quality electrowon copper before proceeding with other phases of the process development. The electrowinning tests showed that removing entrained organic from the electrolyte, maintaining a protective voltage on the anodes when electrowinning was not in progress, and adding a small amount of cobalt to the electrolyte resulted in production of copper cathodes with a low lead content when using antimonial lead anodes. After satisfying these conditions, large variations in other operating conditions were possible without materially affecting the lead content of the electrowon copper. Copper cathodes with lead contents of less than 2 ppm were consistently produced. These results were obtained with laboratory-scale equipment and quantitative extrapolation to industrial-scale operations may not be valid. However, the qualitative effects of the various processing conditions should be applicable to industrial electrowinning.     

A mineralogical study of the deportment and reaction of silver during copper electrorefining

The majority (>95 pct) of the silver in copper anodes occurs in metastable solid solution in the copper matrix; only a small percentage is present in solid solution in Cu₂(Se,Te) inclusions, as a constituent of complex Cu-Pb-As-Sb-Bi oxides or as tiny grains of Ag-Cu alloy. During elec-trorefining, the silver in the copper matrix dissolves, but it is rapidly removed from the elec-trolyte by a variety of reactions. Part of the silver is precipitated in elemental form by cuprous ion, but some of this metallic silver subsequently redissolves. Some of the dissolved silver precipitates as a complex Cu-Ag-Pb-As-Se oxidate phase which agglomerates the particles in the anode slimes, and some reacts with the Cu₂(Se,Te) inclusions liberated from the anode to form, sequentially, silver-bearing copper selenide, AgCuSe, copper-bearing silver selenide, and Ag₂Se. Several selenide species are present in the anode slimes, and individual selenide particles com-monly consist of more than one selenide species. Because of the diversity and complexity of the silver-bearing phases present, the Ag/Se ratio in the anode is only an approximate indicator of the selenide species present in the anode slimes.     

Effect of cobalt added to electrolyte on corrosion rate of Pb-Sb anodes in copper electrowinning

Abstract

Three-layer diffusion couples have been constructed so as to simulate the compositional variations which occur in commercial carbon steels as a result of interdendritic segregation. It has been possible to examine quantitatively the banding behavior in the ternary systems Fe-Si-C, Fe-Mn-C, Fe-Ni-C, Fe-Cr-C, and Fe-P-C both as to the intensity of carbon segregation which occurs in the soaking (austenite) range and during the subsequent γ → a. transformation. The results confirm that the segregation of carbon which occurs before transformation is due to the equalization of the carbon activities. As expected from thermodynamic data, silicon, nickel and phosphorus-rich regions reject carbon while manganese and chromium-rich regions attract it. While this initial segregation is weak, in all cases but nickel it intensifies during transformation. In nickel couples the segregation direction reverses during transformation so that the pearlite-rich regions appear with the nickel. This emphasize s the dominance of constitutional effects in the determination of banding behavior.     

碲渣提取精碲的生产实践

叙述了从铅阳极泥火法冶炼所产碲渣中提取精碲的生产实践,重点介绍了生产中出现的问题和应对措施.     

Progressive degradation of noble metal coated titanium anodes in sulphuric acid and acidic copper sulphate electrolytes

Anodes having a nominal loading of 5 g/m² of 70% platinum—30% iridium alloy on a titanium substrate were employed in repetitive galvanostatic runs at 8.1–540 mA/cm² in 2 M H₂SO₄ electrolyte, with and without the addition of 0.5 M CuSO₄. The increase in anode potential with time was attributed to two causes: passivation of the noble metal surface, and oxidation of the substrate metal beneath the coating. Surface platinum loadings were monitored by an X-ray fluorescence technique, and loss rates averaged 1.30 mg/A h, independent of the operating variables of the present investigation. Surface platinum losses were attributed to a direct electrochemical dissolution process, except in the cases where complete anode degradation occurred which was accompanied by substrate attack and spalling of the noble metal coating.     

The behavior of selenium and tellurium in metal-matte systems

The distribution of selenium and tellurium between molten metal and matte was determined at temperatures of 1100° to 1250°C. The experimental technique permitted separate sampling of each phase while at temperature. Partition coefficients (ratio of weight percent selenium or tellurium in the matte to weight percent selenium or tellurium in the metal) varied from 10.5 to 16.9 for selenium and 5.5 to 8.1 for tellurium. The coefficients decreased with increasing temperature but were essentially independent of impurity concentration, iron content and oxygen and SO₂ partial pressures over the ranges studied. Application of these results to actual operations is discussed. The similarities in the chemical behavior of S, Se, and Te during smelting are also considered.