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By T. Maruyama

Tamano Smelter of Hibi Kyodo Smelting Co., Ltd. has been operating with one Flash Furnace (FSFE) and three Peirce-Smith Converters since its start-up in 1972. Anode production capacity has increased from 101,000 to 263,000 t/y by the several expansion programs, while converter capacity has increased and stable operation has been established by several improvements as listed below. - Expanding the furnace body (length) - Development of two kinds of automatic scrap charging system for each converter. (Increasing the in-stack time and better control of the melt temperature) - Oxygen enrichment at slag blow and copper blow - Increasing the blowing rate This paper reports the details of these improvements.

Jan 1, 1998

By Sh. Najisi, O. Lashkari, M. R. Ghomashchi, A. Charette

"One of-the important parameters in casting and foundry technology is the fluidity of molten metal. This parameter becomes particularly important when casting thin wall parts. Therefore, understanding and controlling fluidity plays a major role in fabricating sound and defect-free cast components.Semi-Solid Metai SSM, slurry is a mixture of solid and liquid, mushy zone, with solid volume fractions of 0.1-0.5 and apparent viscosity close to oil viscosity at room temperature. It flows easily under pressure and capable of making complicated shapes with high degree of die filling and integrity.In this study, the ability of the semi-solid slurry to continue to flow is investigated through the effect of different fraction solids and holding temperatures. The results show that in mechanically stirred, MS, semi-solid 356 Al-Si alloy, increasing fraction solid reduces fluidity. Furthermore, the results of MS-alloy are compared with a newly patented Rheocasting route, i.e. SEED, Swirl Enthalpy Equilibrium Device to highlight the differences of the two processes. In addition, the interrelationships between microstructural evolution and fluidity are discussed."

Jan 1, 2004

By R. Padilla

Enargite (Cu3AsS4) occurs normally associated with copper sulfides, mainly chalcopyrite. When the enargite content in chalcopyrite concentrates is high, direct smelting of the concentrate presents problems related to environmental pollution and contamination of the final metallic copper. Leaching processes are viable alternatives to treat copper concentrates with high content of enargite. Consequently, in this paper, the pressure leaching of enargite in sulfuric acid-oxygen system is discussed. The leaching rate was studied in the range 160 to 220 °C and partial pressures of oxygen of 74 to 200 psi. The enargite dissolution increased substantially with temperature increase. Complete dissolution of enargite was obtained at 220°C, and 100 psi of oxygen pressure in 90 min. The shrinking core model controlled by surface reaction was used to analyze the kinetics of enargite dissolution. Activation energy of 70 kJ/mol was obtained for the temperature range 160 to 220 oC.

Jan 1, 2008

By Michael S. Moats, Alexander Derrick

"The Winand Diagram was developed and has been used for decades to illustrate the interaction between polarization, mass transport and inhibition on the resulting structure of a metal electrodeposit. Recently, Adcock et al. criticized the Winand Diagram and developed their own structural diagram based on nucleation and plating overpotentials. Their work was based on zinc electrodeposition using a galvanostatic staircase method. This work explores the nucleation and plating overpotentials for copper electrodeposition using conditions typical for primary electrowinning and the galvanostatic staircase experimental technique. Additionally, the effects of organic additives and plating substrate on these overpotentials are reported.IntroductionThe control of electrodeposited structures is critically important to modem electrometallurgy operations to insure proper quality and efficient energy use. Electrodeposition of base metals for primary recovery (e.g. electrowinning or electrorefining), while similar to plating for decorative or device manufacturing, differs in the need to produce deposits that cover large areas and grow to significant thickness. Thus, controlling nucleation and particularly growth of electrodeposits is critically important for base metal electrometallurgical operations.The control of nucleation and growth on an industrial scale is most influenced by five parameters - current density, temperature, metal concentration, electrolyte agitation and additives. The effects of these parameters on electrodeposition are interrelated. To describe their effects on the type ofelectrodeposits generated and provide practitioners with a useful tool, Winand developed what is known as the Winand Diagram [1-2]. An adapted version of the Winand Diagram is shown in Figure 1.Winand characterized electrodeposits using Fischer's classification [3] and plotted the various deposit types versus inhibition on a vertical axis and the ratio of current density to bulk metal concentration on the horizontal axis. Inhibition intensity is a complex parameter and is still not well understood even though Fischer introduced the term in 1960 [4]. Often, inhibition intensity is simplified to equal the concentration of organic additive at the deposit surface and is related to the inverse of the exchange current density of the metal being deposited. The ratio of current density to bulk metal concentration is used to represent the ratio of crystallization overvoltage to mass transport of the depositing ion. As such i/iL could also be along the horizontal axis, where iL is the limiting current density of the electrodeposition reaction."

Jan 1, 2012

By Jari Aromaa, Antti Kekki, Olof Forsén

"The deposition of copper on inert substrate depends on the number of active sites that will react at certain overpotential. The critical overpotential depends on surface morphology, surface film resistance and additives on cathode surface. The effects of surface properties on copper nucleation and growth rates were studied for used stainless steel blanks from several tankhouses. The surfaces of the blanks were characterized with electrochemical and mechanical methods. Electrochemical deposition tests were done at current density of 300 A/m2 for 10, 30 and 60 seconds. The nucleation density and copper coverage were estimated using image analysis. The surface film resistance did not correlate with copper growth. Increasing surface roughness correlated with lower copper growth.IntroductionStainless steel cathode blanks in copper electrorefming are usually made of AISI 3 I6L type steel. They have a typical lifetime over 10 years. During use the surface will collect deposits and become rough due to wear and corrosion. These factors can affect the nucleation and growth of copper. The nucleation and deposition of copper on inert substrate depends on the number of active sites that will react at certain overpotential. The critical overpotential can depend on surface film resistance, surface morphology, and additives adsorbed on cathode surface.The deposition potential of metallic ions on a foreign substrate is usually higher than the deposition potential on the electrode made of the same metal due to crystallographic substrate/metal misfit [I]. If the substrate has traces of the depositing metal they will be preferential growth sites. For a smooth deposit a large number of simultaneous nuclei is necessary. However, excessive nucleation density can lead to porous deposits [2]. Surface films of good conductivity are needed for dense nucleation and small nuclei. On cathode blanks the number of active sites increases with increasing surface film conductivity [3-5] and/or surface film porosity [6]. On AISI 3 I6 L stainless steel a more resistive oxide has been found to limit favourable sites for copper nucleation and more conductive film promoted high-density copper nucleation [7]. Also Urda-Kiel et al. have concluded that thicker oxide layers on AISI 304 stainless steel resulted in lower nucleation [8]. Increase in overpotential or current density activates more and more of the potential nucleation sites and this can be seen as higher number of nuclei [9] or smaller average distance between nuclei [10]."

Jan 1, 2012

A novel process is being developed for metal recovery from waste electrical and electronic equipment involving a leach reactor coupled to an electrochemical reactor. Metals such as Ag, Au, Cu, Pb, Pd, Sn etc. are dissolved from shredded electronic scrap in an acidic aqueous chloride electrolyte by oxidising them with aqueous dissolved chlorine species. In the electrochemical reactor: (i) chlorine is generated at the anode for use as the oxidant in the leach reactor, and, simultaneously, (ii) at the cathode, the dissolved metals are electrodeposited from the leach solution. The extended Butler-Volmer equation was used to provide predictions of the electrode potential dependences of partial current densities and, hence, total current densities, current efficiencies and alloy compositions for acidic aqueous chloride electrolytes containing Ag(I), Au(III), Cu(II), Pb(II), Pd(IV) and Sn(IV) species, together with dissolved chlorine. With judicious choice of kinetic parameters, the predicted total current density ? electrode potential behaviour of such solutions was in good agreement with experimental data for a rotating Pt disc electrode. Reduction of dissolved chlorine at a Pt rotating disc electrode exhibited mass transport controlled behaviour, in agreement with Levich?s equation over the potential range 0.3-0.9 V (SHE). This could form the basis of a linear sensor, possibly using a microelectrode for measurement and control of the dissolved chlorine concentration in the efflux of leach reactors and inlet to electrowinning reactors in the envisaged process.

Jan 1, 2003

By Stéphane Bourg

The SCRREEN project gathers more than 50 European initiatives, associations, organisations or independent experts working on Critical Raw Materials (CRM) into a long-lasting network including stakeholders, public authorities, and civil society representatives. SCRREEN contributes to improve the CRM strategy in Europe by (i) mapping primary and secondary resources and substitutes of CRMs, (ii) estimating the expected demand of various CRMs in the future and identifying major trends, (iii) providing policy and technology recommendations for actions improving the production and the potential substitution of CRM, (iv) addressing specific waste electrical and electronic equipment (WEEE) and other End-of-Life (EoL) product issues related to their mapping and treatment standardization, and (vi) identifying the knowledge gathered over previous years and making the data accessible to those beyond the project. As a first step, SCRREEN worked at providing stakeholders with a comprehensive analysis of the current use of the CRM, the mapping of potential primary and secondary resources, and identification of the key technologies used in their production. Substitution profiles, analysis of European business and policy issues pertinent to CRMs, and an identification of the standards, policies, and regulatory frameworks concerning these CRM was also completed. In a second step, to be conducted between mid-2018 and mid-2019, SCRREEN will provide guidance for improving the CRM market in Europe by identifying opportunities from research, development, and innovation (R&D&I) that could reduce the supply and/or economic risks around the most relevant CRM for Europe.

By Alex Moyano

The Peirce-Smith converters are traditionally carrying out the converting process of a copper matte in the smelters of Codelco-Chile. However, its production increment is very limited due to the investment magnitude associated to the fulfillment of the environmental regulation. The objective of this paper is to present the Codelco continuous converting process technological advance when converting mattes and/or white metal into blister copper in a Teniente converter unit as an alternative to increment the corporative anode copper production. In 1994, Codelco-Chile started evaluating its ?home made technology? as an alternative to the traditional batch-type converting process. By the year 2001, the Caletones smelter converted liquid white metal to blister copper in a rearranged PS converter continuously. Then, during the 2001-2003 period, several pilot and industrial scale tests were done in a Teniente converter unit at Codelco Norte smelter, evaluating the continuous converting process, i.e., processing liquid mattes (62-68% Cu) to blister copper, demonstrating its technical feasibility with: (i) both constant production of gas flow and SO2 concentration, (ii) production of liquid slag, and (iii) production of a clean blister copper, suitable for the refining process. The promising results have led Codelco-Chile to plan for the 2006 period, a next advanced stage for the continuous converting process evaluation by carrying out a new campaign of tests in a Teniente converter unit at the Codelco Norte smelter.

Jan 1, 2006

By H. K. Lin

Pyrite oxidation in chloride solutions was investigated with cyclic voltammetry, ac impedance and potential step techniques. The pyrite oxidation in quiescent electrolytes is irreversible and controlled by diffusion. Depression of the semi-circle in the complex plane plot has been explained mathematically based on the concept of the equivalent circuit. When the semi-circle is depressed, the mathematical formula indicates that the reaction resistance should be obtained from the intersection of the semi-circle with Z-axis instead of the semi- circle diameter. The peak charging current densities at 1.10 and 0.90 V vs. SHE obtained from the equivalent circuit coupled with the ac impedance measurements match the peak current densities obtained with the potential step measurements.

Jan 1, 1997

By C. L. Lin

Multiphase, irregularly-shaped randomly-oriented PARGEN particles were grown to determine the breakage/liberation characteristics of such locked particles. The simulated locked particles were randomly broken to establish the liberation characteristics of the broken fragments. The progeny size distributions are consistent with Gilvarry's volume and surface flaw model for single particle breakage. The extent of liberation of both continuous and dispersed phases can be described from the conservation of interfacial area. In this regard the data can be normalized and liberation described for a wide range of dispersed phase grades and dispersion densities.

Jan 1, 1988

By Charles I. Richman

Aquispirillum magnetotacticum (AM) is gram-negative hetrotrophic bacteria that belongs to a class ,of magnetotactic bacteria that have an ecological niche in marine marches and fresh water swamp sediments. Thiobacillus Ferrooxidans (TF) is a Gram-negative, acidophillic chemoliths that may have similar chemical conditions within the cytoplasmic membrane as Aquaspirillum M. to support growth of Magnetosomes. Magnetosomes are cellular bodies that accumulate under slightly aerobic conditions. Magnetotactic motion occurs in an external magnetic field and depends on the medium viscosity. The Atomic Force Microscope equipped with a magnetic tip shows the presence of Magnetosomes in these bacteria strains. The size, shape of magnetosomes in AM and TF strains are characterized.

Jan 1, 1998

By P. D. Nolan

Smelters operating under pollution control orders have become increasingly dependent upon the reliable operation of sulphuric acid plants and no factor affects the long term reliability of those plants more than efficient gas cleaning. The sources and characteristics of contaminants in smelter of fgases and the conventional approaches to removing these contaminants to accepted levels are discussed. New technology is described which offers advantages of lower capital cost, lower operating cost and reduced space requirements over the conventional approaches. This new technology has been developed by LAB s.a. and is licensed for metallurgical gas applications by Chemetics International Company.

Jan 1, 1983

By Stein Tore Johansen

Some ferro-silicon fumaces have heat-recovery equipment. Here, the recovery of electric energy from the off-gases can be increased by increasing the off-gas temperature. This is easily done by reducing the amount of air which usually is mixed into the off-gas to cool the gas mixture. If the off-gas becomes too hot problems with severe fouling or clogging of the gas channels? close to the fumace is observed~ The result is irregular stops to clean the off-gas channels. The paper focuses on the nature? of the clogging phenomena and some of the ways to avoid clogging. A detailed experimental study was carried out at the Elkem Thamshavn Plant. Theoretical studies were performed to understand the particle deposition, turbulent multiphase fluid flow and off gas combustion in the off-gas channels. The study has resulted in reduced clogging.

Jan 1, 1992

By Karin Soldenhoff

Recovery of uranium in conventional ion exchange circuits, using strong base or weak base resins containing quaternary or tertiary amine functional groups, is based on an anion exchange mechanism. In saline liquors, chloride competes with uranium for the active resin sites and reduces resin loading. This results in significant negative impacts on the IX process in terms of plant throughput and operating costs. In this paper we present the results of a study on the recovery of uranium from an acidic in situ leach liquor containing approximately 9 g/L chloride. A range of resins was tested, and a high capacity strong base resin was identified with significantly enhanced loading compared to conventional resins. Other process-relevant criteria such as loading kinetics and elution efficacy are also discussed. The process developed was successfully tested during a recent ion exchange pilot plant operated in conjunction with a field-leach trial.

By A. J. Paul

Traditionally, 16"/50 caliber projectile shells have been fabricated from forged steel. The Naval Surface Warfare Center (NAVSWC) has determined that cost savings of approximately 60% (-$4.7M/year) as well as improved shell fragmentation can be achieved by casting these shells from austempered ductile iron. One of the technical concerns arising out of this material substitution is the role of the casting process in controlling the quality of the cast shells. Optimizing the process through proper orientation of the mold, placement of chills, superheat, etc., can minimize shrinkage porosity and, consequently, flaw size. For this purpose, the mold filling and subsequent solidification of the projectiles was simulated using a 3-D, fully transient, coupled fluid flow and heat transfer model based on finite differences. Several casting orientations were investigated and the casting parameters were varied to optimize the process and minimize casting defects. A comprehensive software tool, which was developed using state-of- the-art visualization techniques, has been used to analyze the process of casting. Emphasis is placed on the use of this visualization tool as an aid to the foundry engineer for process optimization.

Jan 1, 1992

By M. Rubinstein, N. C. Koon, B. N. Das, V. G. Harris

"Copper and gold - based alloys having giant magnetoresistance properties were produced by melt spinning from arc melted and cast rods. The ribbon width varied between 1 and 2 mm and the ribbon thicknesses were in the range of 30 to 50 11m. The uniform microstructure of the cast rods indicated the composition homogeneity in the starting material. The ribbons showed composition uniformity across the cross section from EDX analysis. However, the spun ribbon microstructure changed from a 'frozen in' region near the wheel side to a nanosize spherically precipitated phase towards the freely frozen surface. The evolution of the microstructure from the spun ribbon state to the annealed ones was studied by optical microscopy, SEM and TEM. The structural information of the spun and annealed specimens was obtained from X - ray, electron diffraction, electron microscopy and ferromagnetic resonance. Magnetoresistance was measured by the four point probe method.IntroductionRecently. Giant Magnetoresistance. GMR. has been observed in sputtered thin films alloys of Ag. Au and Cu with Co and Fe [1. 2. 3]. The sputtered films are produced by condensation of the alloys from the vapor phase. These Ag. Au and Cu alloys are miscible and homogeneous in the vapor and liquid phase (except Ag alloys which exhibit phase separation even in the liquid phase) but immiscible and heterogeneous in the solid phase. In our work we have produced thin ribbons of the Cu and Au alloys about 30 µm thick from the miscible state in liquid phase by rapid solidification melt spinning. The microstructural development of the ribbons was investigated in the as - spun condition and on annealing. The other properties such as magnetization. GMR and Mossbauer Spectroscopy were also investigated in the various microstructural conditions of the ribbons."

Jan 1, 1994

By K. Osseo-Asare

Aqueous stability diagrams (25°C) are presented for the systems M-H2O and M-Oxalate-H2O where M=Sm, Nd, Co, and Fe. With the aid of these diagrams (i.e., Eh-pH and log[Metal]- log[Oxalate]), the solution-chemical constraints on metal dissolution and precipitation are identified. By comparing the corresponding stability diagrams, conceptual flowsheets are developed for metal recovery from Sm-Co and Nd-Fe-B magnet scrap.

Jan 1, 1997

By G. Nazari

ERAMET, through its subsidiary COMILOG, have rights to a rich niobium and rare earth deposit inGabon. The Mabounié deposit, is located 50 kmfromthe town of Lambaréné, in a fairly remote location. ERAMET has been developing a process to recover value metals for several years, and approached Hatch Ltd. to design a sizeable Demonstration Plant to help them further optimize the process, and prove the flowsheet is technically viable. The process employs concentration techniques to recover an upgraded Nb/REE feed material for processing in the subsequent leach step. Rare earths and niobium are selectively leached, and subsequently precipitated. Following precipitation, rare earths undergo bulk separation and are purified to produce LRE and mixed MRE/HRE products, which will be further processed by Third Parties. This paper provides a high-level overview of the process, summarizes the motivation for a Demonstration Plant in the vicinity of the deposit, and discusses technical challenges faced during the flowsheet definition and design phase. Key challenges are focused on and summaries of the methodologies used to address each challenge, as well as the solutions to overcome the challenges, are discussed. The paper provides motivation for further process simplification and concludes with a project update.

By Hideaki Tokuyarna

Recovery of metal such as V, Ni and Fe from oil fly ash is important for efficient use of natural resources and protection of environment. Leaching of metals from fly ash followed by ion exchange of leached metals has been examined to develop a process which can selectively recover V and Ni from the fly ash. Experiment of leaching with water, HCI, H2S04 and NaOH leads us to propose a two-step leaching process as an effective and mild operation. The first step is leaching with water for removal of Ni, Mg, A1 and Zn and the second step is leaching with acidic solution for the recovery of V. The metals V and Ni are then separated from other metals in each leached liquor by ion exchange. Advantage of this separation process is that acidic leachant can be reused, which contribute to save separation energy.

Jan 1, 2002

By L. M. . Chia

The successful treatment of waste materials to recover metals with acceptable purity is often hampered by the presence of undesirable impurities. The problem is further complicated by the need to insure that any residues or solutions generated are environmentally acceptable. Hydrometallurgical processes involving leaching- solvent extraction-electrowinning offer some attractive features which address many of these problems. However, in certain instances trace impurities that contaminate the organics are difficult to chemically strip and interfere with the overall process efficiency. A new processing scheme has been developed which appears to provide some attractive alternatives for impurity removal from organics. It has been shown that many ionic impurities can be electrochemically removed from the organic by spontaneous direct reduction using solid metals. A variety of metal ion impurities have been removed from selected common organic extractants such as D2EHPA and TBP using different metals as the reducing agents. The results and probable mechanisms involved in the reactions are discussed.

Jan 1, 1994