Post-mortem Study of Magnesia–Chromite Refractory Used in a Submerged Arc Furnace in the Copper-Making Process

The periodical relining of furnaces because of refractory wear is a cost driver in the copper-making industry. This paper presents a post-mortem study of the refractory lining of a submerged arc furnace used in slag-cleaning operations at the Atlantic Copper Smelter (Spain) after a 6-year campaign. Samples were taken from different locations in the area in contact with slag and analyzed using a scanning electron microscope equipped with an energy dispersive spectroscopy system. New phases were generated as a consequence of the chemical interaction between the molten slag in the bath and the magnesia–chromite refractory lining. The chemical dissolution of the magnesia of the refractory and the incorporation of iron from the slag in the refractory phases were the main drivers. From this interaction, a reaction layer on the hot face of the refractory was formed, whose properties differ from the as-delivered refractory.     

Mechanisms of Guinier–Preston zone hardening in the athermal limit

The interaction of dislocations with Guinier–Preston (GP) zones is a process that contributes to the yield strength of many underaged precipitate-strengthened alloys. Here we use atomistic modeling to investigate this process in an Al–Cu alloy using a newly developed interatomic potential. The study focuses on edge dislocation interactions in the athermal limit. The critical shear stress and the mechanism by which dislocations overcome GP zones is found to vary significantly depending upon GP zone size, orientation and offset from the dislocation glide plane. Dislocation cutting, looping, leading partial cutting with trailing partial looping, diffusionless climb and defect nucleation at the dislocation–GP zone contact point are all observed. In the majority of cases dislocation looping is the controlling mechanism, challenging the applicability of traditional continuum dislocation cutting models to the underaged Al–Cu system at 0 K.     

Degradation behavior of stainless steel in PbO–CaO–SiO2 slag in the presence of sulphur

Five stainless steel grades are subjected to PbO–CaO–SiO₂–S slag at 1200 °C. The degradation phenomena are identified as liquid slag and liquid metal corrosion, oxidation and sulphidation. The relation between sulphidation and steel and slag composition is discussed. For the slag with the lowest PbO/SiO₂ ratio, sulphidation is mainly recognized through (Fe, Cr)_xS_1?x at the surface and in the subsurface of the steel, especially for the steel grades with the lowest Cr content. For the slag with the highest PbO/SiO₂ ratio, sulphidation is mostly pronounced in the steel grades with the highest Ni content through the formation of a liquid (Ni, Pb, S) phase.     

Mechanisms of anelasticity in Fe–13Ga alloy

Thermally activated frequency and temperature dependent anelastic effects in Fe–Ga alloys are practically not studied as yet in spite of the capacity of these alloys to dissipate energy of mechanical vibrations due to magneto-mechanical damping. In this paper we have studied iron-based composition with 13 at.% Ga. Several thermally activated peaks have been discovered and their activation parameters are evaluated by means of temperature and frequency dependent internal friction tests using free-decay and forced vibrations. Physical mechanisms are proposed for most of these peaks. In addition to thermally activated relaxation peaks, an irreversible internal friction peak is recorded due to structural transformation around 200 °C. This peak is frequency independent and is accompanied by inverted modulus behaviour. High damping capacity of Fe–13Ga alloy is confirmed.     

Energy Efficiency of the Outotec<Superscript>®</Superscript> Ausmelt Process for Primary Copper Smelting

The global, non-ferrous smelting industry has witnessed the continual development and evolution of processing technologies in a bid to reduce operating costs and improve the safety and environmental performance of processing plants. This is particularly true in the copper industry, which has seen a number of bath smelting technologies developed and implemented during the past 30 years. The Outotec^® Ausmelt Top Submerged Lance Process is one such example, which has been widely adopted in the modernisation of copper processing facilities in China and Russia. Despite improvements in the energy efficiency of modern copper smelting and converting technologies, additional innovation and development is required to further reduce energy consumption, whilst still complying with stringent environmental regulations. In response to this challenge, the Ausmelt Process has undergone significant change and improvement over the course of its history, in an effort to improve its overall competitiveness, particularly with respect to energy efficiency and operating costs. This paper covers a number of recent advances to the technology and highlights the impacts of these developments in reducing energy consumptions for a range of different copper flowsheets. It also compares the energy efficiency of the Ausmelt Process against the Bottom Blown Smelting process, which has become widely adopted in China over the past 5–10 years.     

Kinetics of the Initial Step of Anodic Formation of CuCl on Copper and Copper–Gold Alloys with Low Gold Contents

By methods of potentiostatic chronoammetry and rotating ring–disk electrode, it is shown that in solutions of a universal buffer mixture (pH 3), in the presence of 0.1 M Cl^–, the kinetics of anodic dissolution of Cu and Cu–Au alloys with an X _Au 1 at. %, at potentials of the formation of a difficultly soluble deposit CuCl is determined by the salt formation. Starting from t 0.25 s, the growth of CuCl is controlled by 2D nucleation with overlapped diffusion layers of neighboring nuclei; latent nucleation centers are activated instantly. As a layer of copper monochloride grows, the control passes to ionic transport through the film, and a gradual decrease in its porosity results in a transient current. The kinetics of anodic formation of CuCl is not observed on Cu–Au alloys with X _Au 4 at. % because of masking by simultaneous solid-state diffusion limitations in the alloy.     

Electrolysis of Magnesia from Bischofite in Qinghai Salt Lakes

1 IntroductionMagnesium industry is confronted with animPortant seedtime in China because of the im-petuous1y extended aPplications of magnestumand its alIoys. The development of magnesiummetallurgy industry finally depends on whetheror not lowering production cost and taking pallin international comPetition[l]. Chaerhan SaltLake in Qinghai province of China, located atthe south central of Chaidamu basin, has exten-sive reserves of about l.62xl09 t magnesiumchloride. In the production proc…     

Research in the Degradation and Antifouling Performance of Copolyesters of L-Lactide and ε-Caprolactonen

Block copolyesters of L-lactide and ε-caprolactone were synthesized by melt copolymerization of ε-caprolactone and L-lactide.The degradation performance of copolyesters was investigated by quartz crystal microbalance with dissipation(QCM-D).Diisocyanate terminated copolyesters could obtain via the reaction of copolyesters and diisocyanate.Diisocyanate terminated copolyesters could react with polyol resin to prepare degradable polyurethane which can be used in antifouling coatings.In this paper,we also discussed the degradation products release action and antifouling performance of the copolyesters film.     

Degradation and recovery of the γ′-phase in heat-resistant nickel alloys

High-alloy nickel alloys are the principal structural material for parts of hot channels of gas turbine engines (GTE), which withstands high temperatures and loads and has a long service life. The high high-temperature strength is a result of complex alloying and phase composition that ensures the stability of the alloy structure in a field of high-temperatures and stresses. The -phase (Ni₃Al-base intermetallic), whose content is determined mainly by the content of Al and amounts to 60–65% in modern alloys, plays a special role in the strengthening process. The article presents results on the phase composition of some high-temperature nickel alloys after service. The degree of degradation of the -phase in a field of high temperatures and stresses and the degree of its recovery under the effect of regenerative heat treatment are investigated.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 4, pp. 29–32, April, 1995.     

The Effect of Microstructure on the Electrical Properties of Gas-Atomized Copper–Iron Metastable Alloys

With the increase in global demand for highly functionalized materials, there is continued interest in exploiting the material properties of metals either individually or in the form of alloys. Copper–iron alloy is considered unique with its remarkable combination of strength and high electrical conductivity. Due to the low cost of iron, this alloy is expected to replace alloys like Cu–Ag and Cu–Nb. In order to explore the microstructural features, copper–iron alloy with three different compositions (10, 30, and 50 at.% Fe) were prepared by a gas atomization process. A detailed microstructural characterization was performed using scanning electron microscopy, X-ray diffraction, and electron backscattered diffraction. Spark plasma sintering was used to sinter the powders to evaluate their electrical conductivities. The mechanism of the microstructure formation is also discussed in detail. As the Fe content increases, the Fe-rich phase changes its shape from spherical to irregular with a concomitant sharp decrease in the electrical conductivity of the alloy.     

Degradation of BPB in photocatalysis enhanced by photosensitizer

The treatment of wastewater containing bromphenol blue （BPB） by WO3/α-Fe203 was studied. Reaction mechanism of photocatalysis enhanced by photosensitizer was probed. The relationships between the composition of heterogeneous photocatalyst, the starting concentration of BPB, amount of photocatalyst, pH, amount of H2O2, illumination time and the decoloring rate of BPB were discussed. The results show that the decoloring rate of BPB can reach 99.1% by using WO3/α-FeaO3 as heterogeneous photocatalyst, with the composition of m（WO3）：m（α-Fe2O3 ）=3：1, the initial concentration of BPB = 15mg/L, the amount of catalyst = 0.300 g, pH= 6.3, the amount of H2O2 =0.2 mL, and the illumination time = 6 h.     

Radiation–Chemical Reduction of Cu2+ Ions in an Aqueous Solution

Protection of Metals and Physical Chemistry of Surfaces - Upon irradiation with accelerated electrons of aqueous solutions of copper salts containing methyl alcohol, the formation of a precipitate...     

The Role of Cu(I) in the Process of Forming Cu2–xS Coatings by a Chemical Route

The interaction of the Cu₂O adsorbed with Na₂S_n (n = 1–4), during formation of the Cu_2–xS coatings has been investigated by cyclic voltammetry.

The summarized reaction of this process has been shown to correspond to the equation:

Na₂S_n + Cu₂O_ad + H₂0 → Cu₂S_ad + (n–1)S^o + 2NaOH,

where S^o/Cu=(n–1)/2. Such a stoichiometry of reaction can be explained by the formation of an intermediate—the adsorbed polysulphide of Cu(I)—and by its subsequent decomposition into Cu₂S and S^o.

When a thicker coating is being formed, i.e., when the surface being coated is repeatedly immersed into an ammoniate solution of Cu(I) and S^o fully bounded:

S^o_ad + 2 Cu⁺ → CuS + Cu²⁺.

At the same time due to different solubility products (L=2.5·10^?48 and 6.3·10^?36 for Cu₂S and CuS respectively), an exchange

CuS_ad + 2(1–x)Cu⁺ → Cu_2–xS_ad+ (1–x)Cu²+ occurs.

After formation of Cu²⁺, parallel processes characteristic for the interaction of Cu(II) with Na₂S_n start to take place, during which S^o is also formed.     

Corrosion Behavior of Copper–Nickel Alloys in Neutral Chloride and Sulfide Containing Solutions

The corrosion behavior of Cu30Ni and 30-1-1 alloys in oxygen-containing chloride solutions (0.1–0.5 N NaCl) with and without Na₂S additive (2–1000 mg/l) is studied with radiometric and electrochemical methods by taking into account the amount of oxygen sorbed in the course of corrosion. In blank solutions, a film of corrosion products is formed on the alloy surface; the thickness and copper content of the film increase with a decrease in chloride concentration. The corrosion rate in sulfide-containing solutions is higher than in sulfide-free ones. In the initial corrosion period, nickel compounds are accumulated in the film. With an increase in sodium sulfide concentration, corrosion accelerates. Additionally alloying the Cu30Ni alloy with manganese and iron reduces its rate by half.     

Composition of Oxide formed on Copper and Copper–Manganese Alloys (5–40% Mn) in Oxygen at 150°–600°c

Abstract

The proportions of CuO and Cu₂O in films formed on copper and copper-manganese alloys in oxygen at temperatures of 150–400°c (600°c for higher Mn alloys) were estimated by coulometric reduction. Only Cu₂O was observed at 150°c. The proportion of CuO increased as the temperature was raised, reaching 82% for copper at 300°c and somewhat lower values for the alloys containing Mn. At temperatures of 350–400°c, the proportion of CuO declined. The oxide remained adherent above 400°c only for alloys with 20% and 40% Mn. From 400° to 600°c the proportion of CuO increased for the 20% alloy but neither CuO nor Cu₂O was found on the 40% alloy.     

Thermodynamic Analysis of the Silicon Effect on Chemical and Electrochemical Stability of Iron–Chromium Alloys

Phase diagrams Fe–Si–O and Cr–Si–O and potential–pH diagrams for the systems Fe–Si–H₂O, Cr–Si–H₂O, and alloy Fe + 25% Cr + 3% Si (-phase)–H₂O at 25°C are constructed. Thermodynamics of the silicon effect on the chemical and electrochemical stability of iron–chromium alloys is discussed.