Precipitation Of Bi Research Articles

Production, purification and formulation of nanoradiopharmaceutical with 211At: An emerging candidate for targeted alpha therapy

IntroductionAstatine-211 has attained significant interest in the recent times as a promising radioisotope for targeted alpha therapy (TAT) of cancer. In this study, we report the production of 211At via 209Bi (α, 2n) 211At reaction in a cyclotron and development of a facile radiochemical separation procedure to isolate 211At for formulation of nanoradiopharmaceuticals. MethodsNatural bismuth oxide target in pelletized form wrapped in Al foil was irradiated with 30 MeV α-beam in an AVF cyclotron. The irradiated target was dissolved in 2 M HNO3 followed by selective precipitation of Bi as Bi(OH)3 under alkaline condition. The radiochemically separated 211At was used for labeling cyclic RGD peptide conjugated gold nanoparticles (Au-RGD NPs) by surface adsorption. The radiochemical stability of 211At-Au-RGD NPs was evaluated in phosphate buffered saline (PBS) and human serum media. ResultsThe batch yield of 211At at the end of irradiation was ∼6 MBq.μA−1.h−1. After radiochemical separation, ∼80 % of 211At could be retrieved with >99.9 % radionuclidic purity. Au-RGD NPs (particle size 8.4±0.8 nm) could be labeled with 211At with >99 % radiolabeling yield. The radiolabeled nanoparticles retained their integrity in PBS and human serum media over a period of 21 h. ConclusionsThe present strategy simplifies 211At production in terms of purification and would increase affordable access to this radioisotope for TAT of cancer.

Reliability Risk Mitigation in Advanced Packages by Aging-Induced Precipitation of Bi in Water-Quenched Sn-Ag-Cu-Bi Solder.

Bi-doped Sn-Ag-Cu (SAC) microelectronic solder is gaining attention for its utility as a material for solder joints that connect substrates to printed circuit boards (PCB) in future advanced packages, as Bi-doped SAC is reported to have a lower melting temperature, higher strength, higher wettability on conducting pads, and lower intermetallic compound (IMC) formation at the solder-pad interface. As solder joints are subjected to aging during their service life, an investigation of aging-induced changes in the microstructure and mechanical properties of the solder alloy is needed before its wider acceptance in advanced packages. This study focuses on the effects of 1 to 3 wt.% Bi doping in an Sn-3.0Ag-0.5Cu (SAC305) solder alloy on aging-induced changes in hardness and creep resistance for samples prepared by high cooling rates (>5 °C/s). The specimens were aged at ambient and elevated temperatures for up to 90 days and subjected to quasistatic nanoindentation to determine hardness and nanoscale dynamic nanoindentation to determine creep behavior. The microstructural evolution was investigated with a scanning electron microscope in tandem with energy-dispersive spectroscopy to correlate with aging-induced property changes. The hardness and creep strength of the samples were found to increase as the Bi content increased. Moreover, the hardness and creep strength of the 0-1 wt.% Bi-doped SAC305 was significantly reduced with aging, while that of the 2-3 wt.% Bi-doped SAC305 increased with aging. The changes in these properties with aging were correlated to the interplay of multiple hardening and softening mechanisms. In particular, for 2-3 wt.% Bi, the enhanced performance was attributed to the potential formation of additional Ag3Sn IMCs with aging due to non-equilibrium solidification and the more uniform distribution of Bi precipitates. The observations that 2-3 wt.% Bi enhances the hardness and creep strength of the SAC305 alloy with isothermal aging to mitigate reliability risks is relevant for solder samples prepared using high cooling rates.

Techno-economic evaluation of antimony and bismuth upcycling from pyrometallurgical copper wastes

The recovery of critical raw materials (CRMs) is important to reduce the supply risk disruption and the dependency on third-countries within the European Union (EU). The present study evaluates the techno-economic implications of antimony (Sb) and bismuth (Bi) recovery from the process stream produced in the polishing stages of the copper electrorefining circuit. The upcycling process was based on the selective precipitation of Sb and Bi from the concentrated hydrochloric acid (HCl) (up to 5–6 M) process stream containing high arsenic (As) concentrations. Four different scenarios were included in the evaluation, in which Sb and Bi were recovered as Sb4O5Cl2(s)/Sb2O3(s) and BiOCl(s)/Bi2O3(s), respectively. The results showed that implementing Bi and Sb upcycling configurations in the copper metallurgical facilities was economically feasible when recovering BiOCl(s)/Sb4O5Cl2(s) and BiOCl(s)/Sb2O3(s) from the eluate stream. Sb recovery was the most cost-intensive process in all the configurations evaluated due to the high chemical requirements needed to neutralize the free HCl excess. The consumption of chemicals represented the most important cost contributor, since high amounts of chemicals are needed for the selective Sb and Bi precipitation. The sensitivity analysis illustrated that recovering these CRMs was economically attractive for all the configurations when achieving Sb and Bi prices above 8.5 and 9.5 €/kg, respectively. Under these CRM prices, the payback period and internal rate of return for the different scenarios range from 4 to 19 years and from 6 to 28 %, respectively. This output highlights that future increase in CRM prices can be an important driver to implement Sb and Bi recovery schemes. Overall, the results of this study highlight the economic potential of implementing Sb and Bi recovery schemes in copper metallurgical plants to align with the ambitious circular economy objectives established by the EU.

Investigating the Effects of Rapid Precipitation of Bi in Sn on the Shear Strength of BGA Sn-Bi Alloys

Investigating the Effects of Rapid Precipitation of Bi in Sn on the Shear Strength of BGA Sn-Bi Alloys

Wettability, Interfacial Behavior and Joint Properties of Sn-15Bi Solder

Sn-15Bi solid solution solder provides a potential replacement for Sn-40Pb solder due to lower cost and similar melting point. Sn-15Bi solder was compared with Sn-40Pb solder to assess the microstructure, wettability, bulk tensile properties, interfacial microstructures in solder joints with a Cu substrate, the interfacial evolution in joints during isothermal aging, and the shear strength on ball solder joints with the effect of aging conditions. The microstructure of Sn-15Bi bulk solder was composed of the primary β-Sn phase with Bi in solid solution and with precipitated Bi phases along the grain boundaries. The wettability of solder alloys was evaluated with wetting balance testing, and the results showed that Sn-15Bi solder had a lower wetting force and longer wetting time than Sn-40Pb solder. The poorer wettability of Sn-15Bi solder was not influenced by different types of soldering flux, but improved with increasing temperature. Tensile tests on bulk solder alloys indicated that Sn-15Bi solder had a higher tensile strength but lower elongation than Sn-40Pb solder. Also, the tensile strength of Sn-Bi solder decreased with decreasing strain rate and with increasing temperature, while the elongation of Sn-Bi solder was independent of the temperature and strain rate. In as-soldered joints, Sn-15Bi solder produced a thicker Cu6Sn5 layer than Sn-40Pb solder. Following isothermal aging, the thickness of the interfacial Cu-Sn intermetallic compound (IMC) increased with the aging time, and the growth rate of the IMC layer in Sn-15Bi solder joints was slightly higher than that in Sn-40Pb solder joints during aging. Ball shear test on solder joints illustrated that Sn-15Bi solder joint had a higher shear strength than Sn-40Pb solder joint, and that with increased aging time, the solder became stronger due to precipitation of Bi, leading to a change in the fracture mode from ductile failure in the solder to brittle fracture at the IMC interface.

Composites of BiVO4 and g-C3N4: Synthesis, Properties and Photocatalytic Decomposition of Azo Dye AO7 and Nitrous Oxide

The composites of BiVO4 and g-C3N4 (BiVO4/g-C3N4) were synthesised by the calcination of a mixture of monoclinic BiVO4 and bulk g-C3N4 at 300 °C for 4 h. Both components were previously prepared by the precipitation of Bi(NO3)3 with NH4VO3 and annealing of melamine. X-ray photoelectron spectroscopy (XPS) identified the presence of C–O and C=O bonds as well as metal nitrides which confirmed the formation of a heterojunction between BiVO4 and g-C3N4. The heterojunction was also indicated by UV–Vis diffuse reflectance (DRS) and photoluminescence (PL) spectroscopy. The band gap energies were determined at 2.42–2.46 eV of BiVO4 and 2.75–2.82 eV of bulk g-C3N4. The specific surface area was 23–28 m2 g−1 of the composites and 6 m2 g−1 and 35 m2 g−1 of pure BiVO4 and g-C3N4, respectively. The photocatalytic activity of the composites was investigated by the decomposition of Acid Orange 7 (AO7) and nitrous oxide. In case of AO7, the BiVO4/g-C3N4 (1:3) composite was the most active one and the main role in the reaction was played by photoinduced holes forming hydroxyl radicals. At the decomposition of N2O, the most important species were the photoinduced electrons and the BiVO4/g-C3N4 (1:1) composite was the most active photocatalyst.

Multistage mineralization at the hypozonal São Sebastião gold deposit, Pitangui greenstone belt, Minas Gerais, Brazil

São Sebastião is a recently discovered Archean gold deposit at the northwesternmost part of the Quadrilátero Ferrífero (QF), southern São Francisco craton, Brazil. The gold ore is strata-confined in two levels of banded iron formation (BIF) of the basal stratigraphic unit in the Pitangui greenstone belt (2.8 Ga). Pitangui is correlated to the widely known Rio das Velhas greenstone belt, which hosts several orogenic gold deposits such as the world-class Cuiabá. The gold mineralization at São Sebastião is associated to replacement-style sulfidation over magnetite, where the main developed phases are: pyrrhotite, chalcopyrite, arsenopyrite, pyrite and arsenian-pyrite. Native Au occurs as inclusions in pyrrhotite formed at dilatation domains (e.g., breccias, fold hinges) during compressional events (Rio das Velhas Orogeny at 2.8–2.75 Ga), but mainly as inclusions in late- to post-kinematic pyrite and arsenopyrite, as fracture infills in arsenopyrite and in contact with gangue minerals. Electron-microprobe analyses in arsenopyrite reveal a 465–560 °C precipitation temperature interpreted from As atomic percentage and indicate that high-temperature fluids were active after the deformational event. The temperature increase caused the incorporation of LA-ICP-MS-detected lattice-bound Ni and Co in arsenian-pyrite and arsenopyrite, related to the mafic-ultramafic signature of boundary rocks. High temperature conditions are supported by pyrite and ISS (intermediate-solid solution in the Cu-Fe-S system) formation at 600 °C and melting-derived textures resulting from the precipitation of Bi- and As-melts, typical of amphibolite-facies environments with high fS2. Whole-rock geochemical assays of drill core samples display two clear trends on Ag, Bi, Cu vs. Au binary plots and on principal component analysis results. The trends are a product of the heterogeneous spatial distribution of melts and high-temperature fluids. Melting features and superposition of mineralization styles are common in hypozonal gold deposits experiencing higher heat influx. At São Sebastião, the thermal effect is likely related to the 2.7 Ga granitic intrusions that surround the Pitangui belt. São Sebastião shows distinct characteristics than those described for the mesozonal gold deposits in the Rio das Velhas greenstone belt and may depict the deeper roots of the QF gold system.

Cu and Ag additions affecting the solidification microstructure and tensile properties of Sn-Bi lead-free solder alloys

Over the past few years Sn-based solders containing third and fourth elements have become of great interest to try and improve the consistency of solders during application. In most reported cases this involved the addition of either Ni in Sn-Cu or Ag in Sn-Bi solder alloys. Still there is a lack of research showing how the combination of third element additions and varying cooling rates affect the mechanical properties of Sn-Bi-X solder alloys. As such the present investigation examines the effects of minor additions of Ag and Cu on a Sn-34wt%Bi solder alloys produced by directional solidification. Directional solidification was used as the transient regime attained during directional solidification in a water-cooled mold may allow for similar cooling rates to those found in industrial reflow soldering operations. Microstructural analysis on the Sn-Bi-X alloys was conducted using eutectic spacing (λE), Bi precipitates spacing (λp) and the secondary dendritic spacing (λ2) measurements. These measurements represented the complex eutectic growth, the solid-state precipitation of Bi within the β-Sn phase and the length-scale of the Sn-rich dendritic array respectively. In conjunction with these measurements the evolution of tensile strength and ductility as a function of λ2 was examined. Considering the Sn-34wt%Bi, Sn-34wt%Bi-0.1wt%Cu, Sn-34wt%Bi-0.7wt%Cu and Sn-33wt%Bi-2wt%Ag alloys, it was found that the modified alloys containing 0.7wt%Cu and 2.0wt%Ag showed lower tensile properties and lower ductility. In contrast, the addition of 0.1wt%Cu increased the ductility for λ2 < 14µm while preserving the tensile strength, representing the best alternative of all alloys examined.

Separation of no-carrier-added astatine radionuclides from α-particle irradiated lead bismuth eutectic target: A classical method

Possibility of separation of no-carrier-added (NCA) astatine radionuclides from the bulk lead-bismuth-eutectic (LBE) target was explored in a simple way in the laboratory scale. A LBE target was irradiated by 40MeV α-particles delivered from a cyclotron facility, India. Quantitative analysis of the irradiated target indicated the production of 210,209At, 207Po radionuclides in the target matrix. The 210,209At radionuclides were separated by precipitation of bulk Pb, Bi and NCA radiotoxic Po radionuclides.

Trace-element geochemistry of pyrite and arsenopyrite: ore genetic implications for late Archean orogenic gold deposits in southern India

AbstractThe distribution of Au and associated trace elements in pyrite and arsenopyrite from late Archean Hutti and Hira-Buddini orogenic gold deposits, eastern Dharwar Craton, southern India was investigated by laser ablation-inductively coupled plasma-mass spectrometry. X-ray element maps acquired by electron probe microanalyser reveal oscillatory zoning of Co and As indicating the crystallization of pyrite and arsenopyrite in an episodic fluid flow regime in which fluid salinity fluctuated due to fault-valve actions. The absence of any relationship between Au and As in pyrite obviate the role of As in the incorporation of Au into pyrite, particularly here and may be generally the case in orogenic gold deposits. On the other hand, positive correlations of Au with Cu, Ag and Te suggest possible influence of these chalcophile elements in the enhanced gold concentrationin sulfides. Pb-Bi-Te-Au-Ag bearing micro-particles (&lt;2 μm) are observed exclusively in micro-fractures and pores in arsenopyrite. The absence of replacement features and element gradient suggests direct precipitation of Pb, Bi, Te, Au and Ag from a fluid that was unreactive towards arsenopyrite. An intermittent fall in fluid pressure caused by the fault-valve action would have resulted in the sporadic precipitation of Au, Pb, Ag, Bi and Te.

Annealing-induced precipitate formation behavior in MOVPE-grown GaAs1−xBix explored by atom probe tomography and HAADF-STEM

The effects of a 45 min anneal at 800 °C on the physical properties and microstructure of a five-period GaAs1−xBix/GaAs1−yBiy superlattice with y ≠ x were studied using room-temperature photoluminesence spectroscopy, high-resolution x-ray diffraction, high-angle annular-dark-field scanning transmission electron microscopy (HAADF-STEM), and atom probe tomography (APT). The anneal resulted in a substantial increase of the photoluminesence intensity over that observed in the as-deposited sample, indicating annihilation of non-radiative recombination centers and stability of the superlattice structure during the anneal. However, some precipitation of Bi from the GaAs1−xBix also occurred. The characteristics of phase separation that occurred within these precipitates were investigated in detail by APT and HAADF-STEM. They indicate that the precipitation reaction involves formation of embedded nano-scale liquid droplets that can accelerate local Bi dissolution from the GaAs1−xBix matrix by moving through it. Preservation of nanometer scale sharp Bi concentration gradients in the growth direction suggested that very little solid state diffusion of Bi occurred during the anneal. The observed gradient in precipitate number density with distance from the sample surface further supports hypotheses of an enabling role of Ga vacancies in the precipitation process.

Complex eutectic growth and Bi precipitation in ternary Sn-Bi-Cu and Sn-Bi-Ag alloys

Sn-34 wt%Bi, Sn-34 wt%Bi-2wt%Ag and Sn-34 wt%Bi-0.7 wt%Cu alloys have been directionally solidified (DS) under a broad range of solidification cooling rates. Microstructures have been characterized with emphasis on both eutectic growth and precipitation of Bi within the β-Sn dendritic matrix. The eutectic growth, for all alloys examined, is shown to be associated with the coexistence of coarse and fine lamellar structures with different length-scale of lamellar spacing (λ). Experimental growth relations of λ vs. the cooling rate have been proposed. The length-scale of the lamellae in the fine eutectic ranges from 0.8 to 2.5 μm while in the coarse eutectic from 1.8 to 4.0 μm. Taking as reference the Sn-Bi alloy, both the spacing between Bi precipitates (λp) and the fine eutectic spacing (λfine) increase with Cu and Ag additions, whereas λcoarse remains roughly unaltered. Both ternary Sn-Bi-Ag and Sn-Bi-Cu alloys are shown to have worse distributions of both lamellae in the fine eutectic and of precipitates within Sn-rich dendrites, which resulted in decrease in hardness.

Gold Mineralization at the Agawa Prospect in Yamaguchi Prefecture, Southwestern Japan

AbstractAgawa gold prospect, located in Yamaguchi Prefecture, southwestern Japan, is a small prospect, where placer gold has been explored and mined since the 17th century. We investigated the prospect to clarify the genesis of the deposit based on the geology, hydrothermal alteration, geochronology, and ore mineralogy. The main mineralized zone of the prospect has a horizontal and vertical extensions of 500 m and 100 m, respectively, and a width of less than 100 m. Gold mineralization in the prospect occurs as dissemination and stockwork veinlets in the intensely sericitized rocks at the apical part of the Agawa dioritic porphyry intrusion at 86.5–88.5 Ma.Mineralization is typified by at least three stages – an early stage characterized by the occurrence of pyrrhotite and native gold; a middle stage by chalcopyrite; and a late stage by pyrite–bornite. Mineral assemblage and fluid inclusion microthermometry estimation suggest a trend of decreasing temperatures from 400°C to 160°C at a constant sulfur fugacity. The mineralizing fluids formed by the mixing of a hypogene fluid of possibly magmatic origin with an external lower‐temperature and lower‐salinity fluid. The mixing process decreased the temperature and salinity of the fluid, resulting in the precipitation of sulfides, native gold and Bi–Te alloys and sulfosalts.The magnetite‐series signature of the Agawa porphyry and related molybdenite‐bearing mineralization indicate that the plutonism of the San‐in granitoids belt extends to the westernmost end of the Honshu Island. The compiled geochronology and distribution of the metallic deposits in the southwestern Japan arc show that transition from ilmenite‐series to magnetite‐series plutonism started earlier in the west, and shifted eastwards with time during the period from Late Cretaceous to Paleogene.

Synthesis and enhanced photoreactivity of metallic Bi-decorated BiOBr composites with abundant oxygen vacancies

Herein, a simple one-pot solvothermal strategy was put forward to obtain metal Bi-decorated BiOBr composites (Bi/BiOBr) with abundant oxygen vacancies. The metal Bi (Bi0) can be deposited into the BiOBr surface via reduction of glycerol solvent in solvothermal process. Precipitation of Bi on surface of BiOBr turned the morphologies of BiOBr from regular flower-like hierarchical architectures to scattered sheets with increase of Bi content, enhanced photoabsorption of BiOBr in whole light region. Interestingly, deposition of metallic Bi (Bi0) on the BiOBr surface could lead to formation of abundant surface oxygen vacancies. As-synthesized Bi/BiOBr composites showed better photocatalytic activity for phenol degradation under sunlight irradiation, as compared with that of BiOBr reference. The enhancement of photocatalytic activities for Bi/BiOBr composites can be attributed to the existence of Bi/BiOBr hetero-structure and abundant oxygen vacancies (as active electron trap), which causing efficient separation of electron–hole pairs in Bi/BiOBr composites.

Effects of minor Cu and Zn additions on the thermal, microstructure and tensile properties of Sn–Bi-based solder alloys

The effects of Cu and Zn additions on microstructures, thermal and mechanical properties of Sn–Bi-based solder alloy were investigated. Thermal analysis indicated that Cu addition decreased both melting point and paste region of Sn–Bi-based solder while Zn played a reverse effect. Alloying Cu into binary solder resulted in an increase in both ultimate tensile strength and ductility. The improved strength of the Sn–40Bi–0.1Cu solder was attributed to the microstructural refinement and uniform distribution of the Cu6Sn5 intermetallic particles. The addition of Zn further depressed the precipitation of Bi, formed uniform globular CuZn2 particles as well as flat blocky Cu5Zn8 phase. The enhanced strength of Zn-containing solder was ascribed to the presence of the globular CuZn2 particles and structural refinement. Needle-like Zn with high aspect ratio forms at the position around the Bi-rich phase and leads a significant decrease of the elongation of Sn–40Bi–2Zn–0.1Cu solder. Fracture surface analysis indicated that the addition of Cu and Zn in Sn–Bi-based solder alloy did not affect the mode of fracture, and all tested solder exhibited brittle fracture with a pattern mixing with tongue and cleavage on the fracture surface.

Effect of Bi‐content on hardness and micro‐creep behavior of Sn‐3.5Ag rapidly solidified alloy

AbstractIn the present paper, the influence of 1, 3, 5 and 10 % Bi (weight %) as ternary additions on structure, melting and mechanical properties of rapidly solidified Sn‐3.5Ag alloy has been investigated. The effect of Bi was discussed based on the experimental results. The experimental results showed that the alloys of Sn‐3.5Ag, Sn‐3.5Ag‐1Bi and Sn‐3.5Ag‐3Bi are composed of two phases; Ag3Sn IMC embedded in Sn matrix phase, which indicated that the solubility of Bi phase in Sn‐matrix was extended to 3 % as a result of rapid solidification. Bi precipitation in Sn matrix was only observed in Sn‐3.5Ag‐5Bi and Sn‐3.5Ag‐10Bi alloys. Also, addition of Bi decreased continuously the melting point of the eutectic Sn‐3.5Ag alloy to 202.6 °C at 10 % Bi. Vickers hardness of Sn‐3.5Ag rapidly solidified alloy increased with increasing Bi content up to 3 % due to supersaturated solid solution strengthening hardening mechanism of Bi phase in Sn matrix, while the alloys contain 5 and 10 % Bi exhibited lower values of Vickers hardness. The lower values can be attributed to the precipitation of Bi as a secondary phase which may form strained regions due to the embrittlement of Bi atom. In addition, the effect of Bi addition on the micro‐creep behavior of Sn‐3.5Ag alloy as well as the creep rate have been described and has been calculated at room temperature. (© 2009 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Indentation creep of lead-free Sn–9Zn and Sn–8Zn–3Bi solder alloys

Creep behavior of Sn–9%Zn and Sn–8%Zn–3%Bi solders together with Sn–37% Pb, as the material for comparison, was studied by indentation tests at room-temperature ( T > 0.6 T m) in order to evaluate the correspondence of the creep results obtained by different methods of analysis, and to evaluate the effect of Bi on the creep response of the eutectic Sn–9%Zn alloy. Stress exponent values determined through these methods were in good agreement. The better creep resistance of the ternary alloy is attributed to solid solutioning effect and precipitation of Bi in the Sn matrix. Both tin-based alloys showed creep resistances higher than that of the Sn–37% Pb alloy.

A comparison of impression, indentation and impression-relaxation creep of lead-free Sn–9Zn and Sn–8Zn–3Bi solders at room temperature

Creep behavior of Sn–9% Zn and Sn–8% Zn–3% Bi solder alloys was studied by impression, indentation, and impression-relaxation tests at room temperature (T > 0.6Tm) in order to evaluate the correspondence of the creep results obtained by different testing techniques, and to evaluate the effect of Bi on the creep response of the eutectic Sn–9Zn alloy. Stress exponent values were determined through these methods and in all cases the calculated exponents were in good agreement. The average stress exponents of 8.6 and 9.9, found respectively for the binary and ternary alloys, are close to those determined by room temperature conventional creep testing of the same materials reported in the literature. These exponents imply that dislocation creep is the possible mechanism during room temperature creep deformation of these alloys. The introduction of 3% Bi into the binary alloy enhanced the creep resistance due to both solid solutioning effect and sparse precipitation of Bi in the Sn matrix.

Decomposition behavior and properties for tin–antimony alloy with bismuth content

The peritectic alloy Sn–10Sb, was chosen as one of the lead-free solder alloys to be subjected to many studies. Bi atoms were added to this alloy in the range of 1–3 wt%. The experimental results obtained from this study show a complete solubility of Bi atoms when added by 2 wt%. More additions of Bi tend to increase the formation of the intermetallic compound SnSb by reducing the precipitations of Sb as a single phase. This intermetallic compound with the precipitation of Bi as a third phase tends to improve the mechanical properties of this alloy.

Mineralogical characterization of a copper anode and the anode slimes from the la caridad copper refinery of mexicana de cobre

A detailed mineralogical study was carried out to characterize a copper anode, the anode-face slimes, the slimes on the bottom of the refining cell, and the autoclave-leached slimes from the La Caridad refinery of Mexicana de Cobre. The objective was to identify possible Pb-Sb-Bi and As-Sb-Bi interactions that could control the Sb and Bi concentrations of the electrolyte. Although some Pb, As, Sb, and Bi can be found in solid solution in the copper crystals of the anode, these elements are mostly present as Cu-Pb-As oxide and Cu-Pb-As-Sb-Bi oxide inclusions at the grain boundaries. During electrorefining, the Pb, As, Sb, and Bi in solid solution dissolve. Part of the Pb, As, Sb, and Bi in the oxide inclusions also dissolves, but part reacts in situ to form PbSO4 and Pb5(AsO4)3(OH,Cl). Some of the dissolved elements reprecipitate as PbSO4, SbAsO4, Sb-As oxide, Sb-As-Bi oxide, Pb5(AsO4)3(OH,Cl), and an oxidate phase of mainly Cu-Ag-AsO4-SO4 composition. Thus, high As contents facilitate the precipitation of Sb and Bi from the electrolyte. Although Pb-Sb oxide and Pb-Bi oxide species were only rarely detected, a high Pb content in the anode may retard the dissolution of the Cu-Pb-As-Sb-Bi oxide inclusions, thereby retaining some Sb and Bi in the raw anode slimes. Autoclave leaching dissolves part of As, Sb, and Bi, but the SbAsO4 and Sb-As-Bi oxide species remain in the leach residue. The Pb is converted almost entirely to PbSO4, which is present as subhedral crystals in the autoclave leach residue.