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.     

A Mineralogical overview of the behavior of nickel during copper electrorefining

Nickel-bearing copper anodes and anode slimes were studied using a variety of mineralogical and chemical techniques. In anodes containing <;0.3 pct Ni, the nickel occurs only in solid solution in the copper matrix. This nickel dissolves simultaneously with the copper during electrorefining, but a small amount reprecipitates as copper-nickel sulfate or a complex Ni-bearing Cu-Ag-As-Se-S oxidate phase in the anode slimes. In anodes containing >0.3 pct Ni, NiO crystals also form. The presence of the Cu-Ni-Sb oxide, kupferglimmer, in the anode depends on its antimony content. Kupferglimmer is prevalent in nickel-rich anodes with high Sb contents (>200 ppm) but is not found in similar anodes with Sb contents <200 ppm. Various Cu-Ni and Ca-Cu-Ni silicate inclusions are present. Depending on the iron content of the anode, Fe-bearing NiO, NiFe₂O₄, and other Ni-bearing iron oxide phases also may be present. All of the oxidate nickel phases remain largely undissolved during electrorefining and concentrate in the anode slimes.     

Identification of arsenato antimonates in copper anode slimes

It was found that, in copper electrolyte, the combination of As(V) and Sb(V) can form arsenato antimonic acid (AAAc) and, the reactions of AAAc with As(III), Sb(III), and Bi(III) can produce the precipitates of arsenato antimonates. During copper electrorefining, the As, Sb, and Bi deposited into the anode slime from the electrolyte are dominant in the forms of arsenato antimonates. It is extremely difficult to separate pure arsenato antimonates from copper anode slimes, while it is easy to synthesize arsenato antimonates using H₂O₂ to oxidize As(III) and Sb(III) in copper refining electrolyte. The composition and structure of the arsenato antimonates were determined with chemical analysis, IR and XRD techniques. The characteristic bands in the IR spectra of arsenato antimonates are δ of As–OH and Sb–OH at 1126.8 cm^− 1, ν_as of As–OH at 1029.7 cm^− 1, ν_as of As–OX(X = As, Sb) at 819.5 cm^− 1, ν_as of Sb–OH at 618.4 cm^− 1, ν_as of Sb–OY(Y = As, Sb) at 507.2 cm^− 1, and ν_as of Sb–OBi at 470 cm^− 1.The arsenato antimonates form irregular masses of amorphous structure because there are many OH groups in AAAc, the OH groups bond with As(III), Sb(III), and Bi(III) at random, which makes the arsenato antimonates formed in copper refining electrolyte have no fixed ratios for As/Sb/Bi. The formation of the arsenato antimonates can be expressed as follows:aH₃AsO₄ + bH[Sb(OH)₆] + cMeO ⁺ →Me_cAs_aSb_bO_{(3a+5b+c/2+1)}H_{(a+5b−2c+2)}·xH₂O + cH⁺ + (a + b + c / 2 − 1 − x)H₂O, where Me = As(III), Sb(III) and Bi(III); a ≥ 1, b ≥ 1, c ≤ (3a + b)     

铜电解阳极钝化及漂浮阳极泥控制技术研究进展

阳极钝化和漂浮阳极泥是影响铜电解精炼稳定生产的主要因素,会造成生产能力的损失、电耗增加、阴极铜质量下降等问题,其形成的主要原因是阳极铜和电解液中含有杂质.目前文献表述中关于阳极钝化的形成机理包括:砷含量对阳极钝化有促进或抑制作用;阳极铜表面生成CuSO4盐膜引起钝化;氧化亚铜与锌粉共同作用引起钝化;氧化亚铜和硫酸铜晶体...     

铜阳极泥浮选尾矿铅、锑、铋定向分离试验

采用工业食盐浸出铜阳极泥浮选尾矿中的铅,硫酸和工业食盐浸出尾矿中的锑、铋,考察液固比、温度、时间、NaCl浓度、H₂SO₄浓度对浸出过程中铅、锑、铋浸出率的影响.研究结果表明:液固比（质量比,下同）为5:1,浸出温度为80 ℃,浸出时间为2 h,NaCl浓度为6 mol/L时,铅、锑、铋的浸出率分别为72.2 %、7.83 %和10.77 %.液固比为5:1,浸出温度为60 ℃,浸出时间为2 h,H₂SO₄浓度为3 mol/L时,锑、铋的浸出率分别为74.97 %和84.27 %.锑、铋水解回收后,水解液可循环利用.      

Activities of As,Sb, Bi,and Pb in copper mattes— Effect of O,Ni, and Co

The effects of oxygen, nickel, and cobalt on the activity coefficients of As, Sb, Bi, and Pb in copper mattes were measured at 1200 °C (1473.15 K) using the transportation method. The transportation experiments concerning the effect of oxygen were carried out as a function of the SO₂ content (1 to 100 vol pct) in the carrier gas and using high- and low-grade matte samples, ≈80 and ≈40 wt pct Cu, respectively. The prevailing sulfur and oxygen partial pressures were evaluated on the basis of matte and carrier gas compositions. The effect of the SO₂ pressure on the activity coefficients was found to be very small compared with the effect of the sulfur pressure, whereas the effect of the SO₂ partial pressure on the vaporization behavior, especially of As, was very significant, due to the additional vaporization of As as AsO gas molecules, which caused an increase in the As removal rate. At a higher oxygen partial pressure than 10^−8.5 atm (3.2·10⁻⁴ Pa) a noticeable decrease in the Sb activity coefficients was observed due to the oxidation. This did not, however, decrease the Sb removal rate, since the relative proportion of the oxide gas molecules in the gas phase increased simultaneously. The interactions between dissolved Ni or Co and the impurity elements were investigated by doping (1 wt pct) the high grade (Cu ≈75 wt pct) matte samples with Ni or Co. At stoichiometric and sulfur-deficient matte compositions, Ni and especially Co decreased the activity coefficients of As and Sb, but did not have any effect on the activity coefficients of Bi and Pb, compared with the corresponding sulfur content in the Ni- and Co-free mattes. For mattes of higher sulfur content Ni and Co did not show any marked effect on the activity coefficients of As, Sb, Bi, and Pb. A. ROINE, formerly with Institution of Process Metallurgy, Helsinki University of Technology, SF-02150, ESPOO, Finland     

Activities of As,Sb, Bi,and Pb in copper mattes

The transportation method was used to determine the activity coefficients of the minor impurity components As, Sb, Bi, and Pb in homogeneous copper mattes (Cu-Fe-S) as functions of the Cu/Fe mole fraction ratio and of the sulfur content of the matte at 1200 °C. All matte samples contained about 0.2 wt pct As, Sb, Bi, and Pb. The activity coefficients were calculated on the basis of primary experimental data and available thermodynamic values of the gas components, which exist over the mattes. The sulfur-to-metal ratio, which controls the activities of the main matte constituents, was found to be the most important factor influencing the activities. When the sulfur-to-metal ratio of the matte changed from sulfur deficit to sulfur excess, the activity coefficient of As varied from 0.52 to 38, Sb from 3.3 to 82, Bi from 75 to 3.4, and Pb from 25 to 0.079 in the matte. The activities of AsS_1.5, AsS, SbS_1.5, BiS_1.5, and PbS had negative deviations from the ideal behavior.     

The mineralogical characterization of tellurium in copper anodes

A mineralogical study of a «normal» commercial copper anode and six tellurium-rich copper anodes from the CCR Refinery of the Noranda Copper Smelting and Refining Company was carried out to identify the tellurium carriers and their relative abundances. In all the anodes, the major tellurium carrier is the Cu₂Se-Cu₂Te phase which occurs as a constituent of complex inclusions at the copper grain boundaries. In tellurium-rich anodes, the molar tellurium content of the Cu₂Se-Cu₂Te phase can exceed that of selenium. Although >85 pct of the tellurium occurs as the Cu₂Se-Cu₂Te phase, minor amounts are present in Cu-Pb-As-Bi-Sb oxide, Cu-Bi-As oxide, and Cu-Te-As oxide phases which form part of the grain-boundary inclusions. About 1 pct of the tellurium content of silver-rich anodes occurs in various silver alloys, but gold tellurides were never detected. Surprising is the fact that 2 to 8 pct of the total tellurium content of the anodes occurs in solid solution in the copper-metal matrix, and presumably, this form of tellurium dissolves at the anode interface during electrorefining.     

Extraction of selenium from copper anode slimes in a sealed leaching system

A new method was proposed for extracting selenium from copper anode slimes with a low concentration of nitric acid in a sealed sulfuric acid leaching system. It is performed under an atmosphere of oxygen which allowed for a cyclic utilization of nitric acid. The effects of main parameters on selenium leaching were studied. The mineralogical characterizations of the typical samples were investigated by XRD and SEM. The results showed that the optimal conditions of the process are considered to be total gas pressure of 0.1 MPa, leaching temperature of 388 K, solid-liquid ratio of 0.20 g mL^–1, H₂SO₄ concentration of 2 mol L^–1, HNO₃ concentration of 0.07 mol L^–1 and leaching time of 2 h. The high selenium leaching efficiency of 99.23% was obtained under these conditions. According to the results of XRD and SEM-EDS, Cu–Ag selenide in the raw anode slimes is difficult to be leached with sulfuric acid alone; copper can be leached more easily from Cu-Ag selenide than silver; selenide is oxidized into the solution, undergoing the intermediate product of elemental selenium.     

197Au Mössbauer study of copper refinery anode slimes

Copper refinery anode slimes are abundantly produced during the electrolytic refining of copper. Although the slimes contain significant and economically recoverable amounts of gold and silver, the chemical state of the gold has not been fully identified. In the present work, the chemical form of gold in a copper anode, in a raw slime, and in slimes treated by different leaching procedures has been investigated by Mössbauer spectroscopy with the 77.3 keVγ-rays of¹⁹⁷Au. The Mössbauer spectrum of the anode is typical of a dilute Au:Cu alloy. The spectrum of the raw slime consists of two components, namely, a single, rather broad line with an isomer shift (IS) of about ?0.3 mm/s relative to a Pt metal source and a quadrupole doublet with an IS of + 1.2 mm/s and a quadrupole splitting of 5.0 mm/s. The single line component can be attributed to a gold-rich alloy, with an approximate composition of Au₆₀Ag{n40} or Au₈₀Cu₂₀ if it is a binary alloy, or to a ternary Au-Ag-Cu alloy of appropriate composition. The parameters of the quadrupole doublet match those of Ag₃AuSe₂ (fischesserite) or related Ag_2?xAu_xSe compounds. In these compounds, the gold atoms are coordinated by two selenium atoms in a linear arrangement, as is typical for Au(I). It was found that the ratio between the concentrations of the metallic phase and the selenide strongly depends on the leaching conditions. The measurement of the Lamb-Mössbauer factor of fischesserite is also reported.     

The co-precipitation of copper and zinc with lead jarosite

The formation of lead jarosite, Pb_0.5Fe₃(SO₄)₂(OH)₆, in the presence of dissolved copper and/or zinc results in a significant substitution of these metals in the jarosite phase; the co-precipitation is most pronounced in sulphate media but also occurs, to a lesser degree, in chloride solutions. The copper and/or zinc substitute for iron, and under extreme conditions the product approaches beaverite, Pb(Cu,Zn)Fe₂(SO₄)₂(OH)₆, in structure and composition. The extent of co-precipitation increases sharply with increasing concentrations of dissolved CuSO₄ or ZnSO₄ and slightly with either an increasing stoichiometric ratio of PbSO₄/Fe³⁺ or increasing ionic strength. The co-precipitation of copper or zinc is not significantly affected by acid concentration although the yield of product declines with increasing concentration of H₂SO₄. The extent of reaction is relatively insensitive to reaction temperatures in the range 130–180°C and to reaction times in excess of 2 h. Copper is strongly co-precipitated in preference to zinc from solutions containing both metals. Other divalent base metals such as Co, Ni and Mn are also co-precipitated with lead jarosite although not to the same degree as copper or zinc.     

铜阳极泥处理工艺的研究进展

综述了国内外对铜阳极泥处理工艺的研究,包括对有价金属回收有影响的砷、锑、铋等贱金属去除工艺以及金、银、铜、硒、碲和铂族金属回收工艺,并对今后研究方向进行了展望。     

The mineralogical deportment of germanium in the Clarksville Electrolytic Zinc Plant of Savage Zinc Inc.

A mineralogical study was carried out on the neutral leach residue and weak acid leach residue generated from Gordonsville zinc concentrate at the Clarksville Electrolytic Zinc Plant of Savage Zinc Inc. The intent was to characterize the mineral forms and associations of germanium. The Gordonsville zinc concentrate consists mostly of sphalerite which has a solid solution Ge content of ~400 ppm; the sphalerite is the dominant, if not only, Ge carrier in the concentrate. The neutral leach residue consists principally of iron gel-silica gel, ZnO, and basic zinc sulfate, (Zn,Cu)₄(SO₄)(OH)₆·4H₂O, together with minor amounts of ZnFe₂O₄, sphalerite, Zn₂SiO₄, Zn-Fe-Pb silicate, and PbSO₄, as well as traces of quartz, silicates, Pb-K jarosite solid solution, Fe₂O₃, and FeO·OH. The major Ge carrier is the iron gel-silica gel phase, but modest amounts of Ge are present in the ZnO, ZnFe₂O₄, sphalerite, and Zn-Fe-Pb silicate phases. The weak acid leach residue consists mostly of iron gel-silica gel, ZnFe₂O₄, PbSO₄, Pb-K jarosite, Zn-Fe-Pb silicate, and quartz. The major Ge carrier is the iron gel-silica gel phase which contains up to 1.7 pct Ge and accounts for ~70 pct of the total Ge content of this residue. The remaining Ge is carried by the Zn-Fe-Pb silicate, ZnFe₂O₄, and some of the rare Mn-Pb-Fe oxide phases.     

Mineralogical characterization of silver flotation concentrates made from zinc neutral leach residues

Silver flotation concentrates prepared from high-silver (1480 ppm Ag) and low-silver (300 ppm Ag) neutral leach residues have been examined mineralogically to determine the phases present and to elucidate the behavior of silver during zinc processing. The flotation concentrates consist principally of sphalerite although lesser amounts of zinc ferrite and PbSO₄, as well as traces of other phases, also are present. In the high-silver flotation concentrate, silver occurs mostly as Ag₂S or (Ag, Cu)₂S rims on sphalerite although (Ag, Cu)₂S inclusions within sphalerite also are present. Trace amounts of a Cu-Ag-S-Cl phase are present on rare copper oxide grains, and this silver-bearing phase may be a fine mixture of Ag₂S, AgCl, and Cu₂S. In the low-silver flotation concentrate, silver occurs mostly as Ag₂S although traces of silver-bearing CuS and Cu₂S also are present. The Ag₂S occurs as <1 μm particles disseminated in elemental sulfur-silica gel patches, as discontinuous rims or isolated patches on sphalerite grains, and as tiny free particles. Silver chloride was not detected. These studies suggest that silver dissolves during neutral leaching and subsequently reacts with sphalerite or other sulfides to form silver sulfide.     

Mineralogical characterization of silver flotation concentrates made from zinc neutral leach residues

Silver flotation concentrates prepared from high-silver (1480 ppm Ag) and low-silver (300 ppm Ag) neutral leach residues have been examined mineralogically to determine the phases present and to elucidate the behavior of silver during zinc processing. The flotation concentrates consist principally of sphalerite although lesser amounts of zinc ferrite and PbSO₄, as well as traces of other phases, also are present. In the high-silver flotation concentrate, silver occurs mostly as Ag₂S or (Ag, Cu)₂S rims on sphalerite although (Ag, Cu)₂S inclusions within sphalerite also are present. Trace amounts of a Cu-Ag-S-Cl phase are present on rare copper oxide grains, and this silver-bearing phase may be a fine mixture of Ag₂S, AgCl, and Cu₂S. In the low-silver flotation concentrate, silver occurs mostly as Ag₂S although traces of silver-bearing CuS and Cu₂S also are present. The Ag₂S occurs as <1 μm particles disseminated in elemental sulfur-silica gel patches, as discontinuous rims or isolated patches on sphalerite grains, and as tiny free particles. Silver chloride was not detected. These studies suggest that silver dissolves during neutral leaching and subsequently reacts with sphalerite or other sulfides to form silver sulfide.     

Electrometallurgy of copper refinery anode slimes

High-selenium copper refinery anode slimes form two separate and dynamically evolving series of compounds with increasing electrolysis time. In one, silver is progressively added to non-stoichiometric copper selenides, both those originally present in the anode and those formed subsequently in the slime layer, and in the other, silver-poor copper selenides undergo a dis-continuous crystallographic sequence of anodic-oxidative transformations. The silver-to-selenium molar ratio in the as-cast anode and the current density of electrorefining can be used to construct predominance diagrams for both series and, thus, to predict the final bulk “mineralogy” of the slimes. Although totally incorrect in detail, these bulk data are sufficiently accurate to provide explanations for several processing problems which have been experienced by Kidd Creek Division, Falconbridge Ltd., in its commercial tankhouse. They form the basis for a computer model which predicts final cathode quality from chemical analyses of smelter feed.     

高镍铜阳极泥和高铅铜阳极泥特征对比研究

高镍和高铅阳极泥是两种常见的铜阳极泥。本文研究了两种阳极泥的化学成分、物相组成、结构特征,比较了其异同点,为贵金属、稀有金属的提取工艺提供理论依据。采用XRD,SEM和显微镜的方法对两种阳极泥分别进行了工艺矿物学研究,并对其结果进行了对比研究,研究表明:两种阳极泥的粒度分布相近,<38μm的阳极泥都占80%左右;化学成分方面,高镍铜阳极泥比高铅铜阳极泥含铜、镍高,金、银少。此外,高铅铜阳极泥中常含有As、Sb、Bi,是铜阳极泥处理的难点;物相组成和结构特征方面,高铅铜阳极泥较高镍铜阳极泥更为复杂。     

分子识别技术在铜工业应用中的最新进展

分子识别技术(MRT)——一种高选择性分离技术的使用,对于铜的电解精炼和电积系统中的多种阳离子和阴离子,证明是一种成本低、效益高、环保好的处理技术。这些离子包括重金属、过渡金属、贵金属、卤化物、碱金属/碱土金属离子。本文总结了分子识别技术(MRT)在各种令人感兴趣的领域中的应用:从铜阳极泥中回收和精炼铂族金属,从矿山酸性排水中回收铜;从铜电解精炼和电积过程中提取Bi、Sb和Cl。     

Effects of CaO, Al2O3, and MgO additions on the copper solubility, ferric/ferrous ratio, and minor-element behavior of iron-silicate slags

The effects of CaO, Al₂O₃, and MgO additions, singly or in combination, on the copper solubility, the Fe³⁺/Fe²⁺ ratio in slag, and on the minor-element behavior of silica-saturated iron silicate slags were examined at 1250 °C and a p _O2 of 10⁻¹² to 10⁻⁶ atm. The results indicated that copper solubility in slag was lowered with the addition of CaO, MgO, and Al₂O₃, in decreasing order. The Fe³⁺/Fe²⁺ ratio in the slag decreased with the additions, but this effect was smaller at lower oxygen potentials. The presence of small amounts (about 4 pct) of CaO, Al₂O₃, and MgO in the slag resulted in increased absorption of Bi and Sb into molten copper, but had a smaller effect at large additions (about 8 to 11 pct). The distribution behavior of Pb was a function of oxygen partial pressure, which indicates the oxidic dissolution of Pb in the slag as PbO, while the behavior of Bi, Sb, and As was found to be independent of oxygen potential, supporting the atomic (neutral) dissolution hypothesis of these elements in the slag. The distribution behavior of Pb and As was not significantly affected by the additions. The activity coefficients of Bi and Sb in the slags were determined to be as follows: (1) for no addition, γ _Bi=40 and γ _Sb=0.4; (2) for small additions (about 4.4 pct), γ _Bi=70 to 85 and γ _Sb=0.8; and (3) for large additions (about 8 to 11 pct), γ _Bi=60 to 75 and γ _Sb=0.5 to 0.7.