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By Maria K. Kojo

The interaction between various slags and a nickel concentrate containing pyrite, pentlandite, and violarite were investigated by submerging concentrate pellets in molten slags. The slags were contained in MgO-A12O3 spinel crucibles. The slag oxidizes the iron sulfides in the concentrate, resulting in a nickel matte. The amount of S02 gas formed during reaction was measured to determine the oxidation reactivity of the slags. The experimental variables included temperature, the ferric/ferrous ratio of slag, and other slag properties such as the FeO/SiO2 ratio and the MgO and NiO contents. The reactivity of the slag depended in a complex manner on its oxidizing power, viscosity, and interfacial tension. The slag composition for the greatest reactivity was determined to be Fe3+/Fe2+ = 0.3, Fe/SiO2 = 1.3, and % MgO = 2. This slag, however, caused substantial foaming. Increasing the MgO content to 10% or replacing it by 5% MgO + 8% NiO eliminated at a slight decrease in reactivity. The implications of the findings from this work in the bath smelting of nickel sulfide concentrates are discussed.

Jan 1, 1995

By Henry Hu

In high pressure die casting processes, proper control of temperature die yields a high casting production rate and superior quality components, Die temperature is usually influenced by various die design and process parameters such as size and location of intemal water cooling lines, flow rates of cooling lines, and pouring temperature of molten metal. Among them, the cooling water flow rate plays a major role in controlling thermal pattern of the die_ In order to develop an effective control strategy, data of local die temperature must be collected and analyzed, In this study, a PC-based data acquisition and control system (DACS) for die temperature control has been designed, and established, The developed DACS has three input channels for temperature signals and one input channel for water flow rate signals, as well as one output channel for a water pump, and is capable of displaying data in both curve format and value format. Implementation of the DACS in a laboratory setup has also been attempted, It should be pointed out that more advanced control mechanisms can be potentially integrated into this system in future,

Jan 1, 2003

By Gerald K. Vellente

Producers of strip coated products are being approached by users to supply higher quality products and adhere to tighter specifications. Suppliers, in an attempt to assist the producers, must consider new technologies for equipment. In the past several years, the induction melting and heating industry has made great strides in developing new and innovative equipment, while improving existing technology. In the past several years, the induction melting and heating industry has made great strides in developing new and innovative equipment, while improving existing technology. In the past several years, the induction melting and heating industry has made great strides in developing new and innovative equipment, while improving existing technology. This paper will review recent developments to include improved refractory systems for ceramic pots, new channel-type inductors which are more efficient, new power control systems for existing channel-type pots, and innovative use of multi-purpose lines. Additionally, new heating applications such as galvannealing, edge heating, and post heating will be reviewed. Advanced math models for controlling heat will be discussed. Producers can easily meet the demands of their customers because of the flexibility provided by the equipment reviewed.

Jan 1, 1992

By Sergio Neves Monteiro, Nuã Simonassi, Helvio Pessanha Guimarães Santafé Jr.

"Thermoset polymers, like the polyester, become harder with increasing temperature owing to molecular crosslink formation, which is a thermal benefit for composite matrix applications. Natural lignocellulosic fibers, however, have low thermal resistance and tend to degrade with increasing temperature. Therefore, the combination of a lignocellulosic fiber, as reinforcement, with a thermoset polymer, as the matrix, results in a composite material with complex thermal behavior. In the present work, a thermal analysis was conducted on polyester composites with different amounts of coir fibers. Both TGA and DTG curves were analyzed to determine the effect of the coir fiber on the thermal resistance of the composites. It was found that the coir fiber sensibly affects the thermal behavior of the polyester matrix for fiber amounts above 10% in volume. This effect is associated with an increase in thermal degradation.IntroductionIn recent years, there has been an increase application of natural fibers as reinforcement of polymer matrix composites in several industrial sectors, with special participation in automobile components [1-3]. Figure 1 illustrates the different components of a modem BMW sedan that are fabricated with lignocellulosic reinforced polymer composites."

Jan 1, 2012

By L. Trincado

Mantoverde is a heap leach-SX-EW plant that was commissioned in December 1995 at a production rate of 42,130 ton of copper per year and 5.4 million ton of ore per year. Copper production has steadily been increased to 57,290 ton in 2002. Forecast copper production for 2003 is 60,000 ton for an ore treatment rate of 8.5 million ton. Several improvements in the heap leach process have been implemented. The main process improvements are related to the optimization of heap height, particle size, irrigation rate and leach cycle, in addition to a better heap drainage design and a solution management system. A first dump leach operation was started in 1999 at a production rate of 1,922 ton of copper. A second dump leach operation was started in early 2002 at a production rate of 2,805 ton of copper. Dump leach production will be increased over time to as much as 24,000 ton of copper. The main heap leach process improvements, as compared to the original plant design, as well as the main dump leach operating parameters are discussed in this paper.

Jan 1, 2003

By Seung-Whee Rhee

Characteristics of ceramic support made by spent foundry sand-loess mixtures are investigated by bulk density, porosity, durability, and compressive strength. And the basic properties of SFS and loess are estimated. The effect of drying time after cutting process, elevated temperature time, sintering temperature, and sintering time is also estimated to obtain the optimal condition in the process of manufacture ceramic supports. From the basic properties of SFS and loess, the content of SiO2 in furan sand is much higher than that in loess but the content of Al2O3and Fe2O3 in furan sand is much lower than that in loess. In order to make ceramic supports cylinder shape is the most desirable to sustain the properties of ceramic support. If annulus shape has a enough compressive strength, however, annulus shape may be decided. For the optimal condition to manufacture ceramic supports, drying time after cutting process is decided to 24 hrs and elevated temperature time is decided by 9hrs. And sintering temperature and sintering time are decided to 900 and 9hrs, respectively in order to prevent solidification of sand materials.

Jan 1, 2006

By J. M. Casas

This work presents the development of an ionic equilibrium model and its use to simulate the distribution and concentration of chemical species (speciation) in sulfuric acid - cupric sulfate solutions in the 0-2 pH range, 0.1-10 gpl copper concentration range and 15-45°C temperature range. The model consists of a set of equations which represent the equilibrium relationships for the ionic reactions and the mass balances for the components present in the system. The effect of ionic strength was taken into account by correcting the equilibrium constant in concentrated solutions. Several species can be formed at different pH and temperature values, the principal being: HSO-4, SO42-, CuSO4(aq), Cu2+, and H+ in order of increasing solution acidity. Simulations show that concentrations are highly dependent on pH. The sulfuric acid speciates mainly as bisulfate ion (HS0-4) and hydrogen ion (H+) at pH values lower than 1. The model presented in this work can be applied to predict and analyze the solution composition in electrolytic copper processes such as electrowinning, electrorefining and electrodialysis, as well as the purification of various industrial solutions.

Jan 1, 1999

By Daniel Kittelty

A fully instrumented laboratory electrowinning cell has been used to produce nickel cathodes from synthetic solutions containing various impurities in order to evaluate the effects of both metallic ions and organic reagents (from prior solvent extraction and other processes) on the quality of the electrodeposited nickel. The conditions used were typical of those employed in industrial electrowinning operations. The impurities were found to alter the crystal size and shape, induce the development of hydrogen pits on the deposit surface, incorporate as metal hydroxide crystals in the deposit, and alter the internal stress and current efficiency. These effects have been interpreted in terms of previously established relationships between the solution composition and the physical properties of the cathodes. The incorporation of the common metal impurity ions into the deposit have been interpreted in terms of a mass transport controlled reduction or precipitation reactions. In particular, a low concentration of aluminium ions resulted in an initial highly deleterious effect, which was replaced by a positive influence at higher concentrations. A model which involves the buffering effect of the aluminium on the pH at the cathode surface has been proposed.

Jan 1, 2003

By John Wallace, Chib Iheagwara

"Refinements in sensor design have produced low-cost rugged elements to act as loop coupled with stable detection hardware for eddy current measurement in difficult environments. This has allowed direct dimension gauging of nonferrous and ferrous products above the curie point for absolute dimensions and electrical conductivities independently. The software was developed for the analysis of electrical conductivity profiles in CZ silicon crystal growth, then refined for monitoring bar properties and tube properties. Since in most metal working operations, speeds at the minimum of a few hundred feet per minute are encountered the design of the gauge was optimized for a rapid measurement. Independently extracting electrical conductivity provides data in some metal systems for determining the temperature of the monitored product.IntroductionThe primary reason for the use of eddy currents in gauging is that in hostile environments of metal working techniques such as laser gauging and ultrasonics are not always robust enough for in process measurements. Our goal is to use the technique of eddy current measurement as a quantitative control element in various hot and cold processing operations. Inspection in the early stages of metal and semiconductor processing is usually too costly to introduce in a well developed process and these tools are usually only employed in process development. Until recently there has been no efficient general analysis to allow real time measurements in the cylindrical and the probe geometry that could separate dimensional changes from material property changes both which effect the eddy current response. The basis for these measurements is that forward electromagnetic problem for conductors can be solved exactly for the test geometry which allows an inverse analysis to be made by relaxing the dimensions and conductivity to values which reproduce the measured response[!]. This transformation is based on analysis developed in Robert Siegfried' s thesis and was explored both by modeling and by physical measurement. This analysis was extended over the last few years to allow a more compact data set to be used to exact physical properties. The main result was that the technique would work on high ·quality physical data on as little as three test frequencies with the penalty being that the analysis is computational intensive. The main result of this work was that a quantitative inverse analysis of eddy current response would allow a general instrument to be used for a variety of measurements rather than being tailored for a specific measurement on a specific material test geometry. The development of these instruments has progressed over the last ten years for monitoring real time solidification, crystal growth[2] and hot seamless tube forming where the use of standards in traditional eddy current is limiting. The specific instrument design was dictated by the requirements of the algorithm for both frequency selection and levels of systematic noise that could be tolerated. Because the data is need for real time information this dictated that the system be a parallel multifrequency eddy current instrument feeding the same sensor. The sensor have to be simple and robust and usually a single loop or several loop of heat resistant wire or tube. This presentation is about using inversion of multifrequency eddy current data in real time to produce dimensional and property data on cylindrical conductors and planar conductors in real time. The object of the measurements is to produce dimensional outputs on measurements of conducting material without having to establish a detailed standard for each material or size tested. The dimensional measurements using eddy currents is complicated by material variations in conductivity due to temperature and composition. Those variations that are not geometric are often not of critical interest and complicate the measurement. The dimensional changes are often of more importance"

Jan 1, 1997

By Michael G. Mayer

Since its invention in 1859 various designs of lead batteries have evolved to meet commercial needs for traction applications and standby power. In recent years major developments have taken place in lead alloys and the chemistry and mechanical design of industrial lead batteries. These are reviewed in relation to their commercial application together with the new type of maintenance free gas re-combination lead-acid batteries which are opening so many new markets for lead.

Jan 1, 1990

By Jr. Pomykala, B. J. Jody, E. J. Daniels

Each year, about five (5) million ton of shredder residues are landfilled in the United States. ·Similar quantities are landfilled in Europe and the Pacific Rim. Landfilling of these residues results in a cost to the existing recycling industry and also represents a loss of material resources that are otherwise recyclable. In this paper, we outline the resources recoverable from typical shredder residues and describe technology that we have developed to recover these resources.

Jan 1, 2000

By Alexey T. Kovalev, Irina A. Khabarova, Valentine A. Chanturiya, Igor Zh. Bunin, Elizaveta V. Koporulina

"The paper presents new theoretical and experimental results about mechanisms of disintegration of mineral complexes and structural transformations of the sulfide surface under high-power nanosecond electromagnetic pulses (HPEMP). The heated gas outflow from nanosecond breakdown channels of sulfide minerals under HPEMP is considered. It is shown that the gas outflow from channels can be an additional destructive factor in the processes of the electric pulse discharge disintegration of mineral complexes. It is shown that the effect of HPEMP changes chemical surface composition and, respectively, technological properties of pyrrhotite and pentlandite. Morphology and elementary composition of new micro- and nanoformations on mineral surface of pentlandite and pyrrhotite have been investigated using up-to-date methods of SEM/EDX and Scanning Probe Microscopy. Preliminary electropulse effect on mineral products before flotation allows producing optimal conditions for flotation separation of pentlandite and pyrrhotite owing to forming the new nanophases and defects on the surface of sulfides.IntroductionThe effectiveness of High-Power Nanosecond Pulses in the disintegration and liberation of fine disseminated mineral complexes and the recovery of micro- and nanoparticles of precious metals from refractory ores was demonstrated in [1, 2]. Possible mechanisms of selective disintegration were considered in [1-3]. It has been shown both theoretically and experimentally that electric breakdowns can play an important role in the nanosecond pulsed treatment of milled minerals (e.g., semiconductor sulfides and quartz with particle sizes of 100 µm to 2-3 mm) that are carriers of finely disseminated gold and other valuable components. Electric discharges in such minerals are accompanied by a destruction of integrity in the form of breakdown channels and the formation of a system of cracks around these channels [3]. The development of the domains of induced cracks around the channels is determined by the pressure of evaporated material in the breakdown channel. Upon an instantaneous energy release in a channel (nanosecond discharges), the change in its transverse size and in the gas density and pressure in the channel is determined by (i) the radial motion of the evaporation wave, (ii) the radial expansion of the channel, and (iii) the heated gas outflow from the channel. The evaporation wave moves with a speed on the same order of magnitude as the speed of sound (or greater) and travels a distance of around the initial channel radius, i.e., a much smaller distance than the breakdown channel length."

Jan 1, 2011

By Maribel L- Saucedo-Muñoz, Toshiyuki Hashida, Victor M. Lopez-Hirata, Shin-Ichi Komazaki

"Small-punch tests were conducted at 4, 77 and 293 K on three types of austenitic stainless steels JNl, JJl and JK2, which were solution treated, water-quenched and then aged at 923, 973, 1023 and 1073 K for 5 h. Small-punch test energy was employed for the evaluation of the aginginduced embrittlement behavior in these materials. Fracture surface of small punch test specimen for the solution treated steels exhibited a ductile fracture, showing the highest SP test energy values. The presence of intergranular brittle fracture was observed in aged specimens. Smallpunch test energy decreased significantly as the aging process progressed. The highest and lowest decrease in small-punch test energy with aging temperature occurred in JNl and JK2 steels, respectively. The decrease in small-punch test energy showed to examine appropriately the aging-induced embrittlement in these materials. The difference in aging-induced embrittlement behavior for these steels was explained based on the volume fraction of intergranular precipitates in aged samples.IntroductionA high level combination of strength and toughness is required for cryogenic structural materials used in the superconducting magnets of fusion nuclear reactor. This requirement is beyond the capability of conventional austenitic stainless steels [1]. The Japan Atomic Energy Research Institute (JAERI) developed new cryogenic JNl, JJl and JK2 austenitic stainless steels. The structure of superconducting magnets is supposed to be constructed by welding thick plates of this kind of steels. Thus, most of the components are exposed to thermal cycles. The slow cooling may cause microstructure changes in both the base material and weld zone. These changes may also decrease the fracture toughness of these materials at cryogenic temperatures. Therefore, it is important to study the effect of thermal aging on fracture toughness behavior for these steels. Konosu et al. [2] carried out a study of the effect of thermal aging on the mechanical properties for JNl steel using tension and fatigue tests. Kwon et al. [3] evaluated the deterioration in fracture toughness at cryogenic temperatures for the isothermally aged JNl steel by means of the Small-Punch (SP) test. No other reports were found about the cryogenic fracture toughness behavior for this kind of steels. To evaluate the cryogenic fracture behavior, the elastic-plastic Jrc value is a good alternative [4,5]; nevertheless, the standard required specimen size makes it difficult to be used for the fracture toughness evaluation in small zones."

Jan 1, 2011

By R. C. Chaturvedi, S. B. Padwal

"Padwal and Chaturvedi have developed the model based on M-K theory, considering Hosford's yield criterion and critical thickness strain criterion"" to predict the sheet metal forming limits under simple (constant) strain ratio paths. This analysis has been extended in this paper to predict the sheet metal forming limits under complex strain paths. The effects of exponent ""a"" in Hosford's yield criterion and strain paths on the forming limits under complex strain paths are studied using this analysis. The predictions of the present analysis are compared, both for simple and complex strain paths, with experimental results of Ishigaki for A.K. steel and also with the predictions of Rao and Chaturvedi's model. The quantitative analysis of the error in predicting the forming limits has also been carried out using a method suggested by the authors earlier.1. INTRODUCTIONThe constant strain ratio condition has been assumed in the theories developed for prediction of forming limit diagrams (FLO). In actual forming operation, this condition is seldom satisfied. Even in the case of simple single stage press formed components, the strain path becomes curved and non-linear. In the case of pressings with complex shapes, or multiple stages of forming, the changes in strain path are more pronounced and even abrupt.Experimental study of the forming limits, under two stage strain paths, by Ishigaki [1], has shown that the forming limits are path dependent. It has been observed that the forming limits lower than that under simple strain paths, may be obtained under certain strain paths (when the first stage strain path is either equibiaxial tension or uniaxial tension, followed by the second stage strain path as plane strain). Rasmussen's work [2J, on the theoretical study of forming limits under curvilinear strains paths, has shown that a large drop in formability can result from very small changes in strain path. Thus if a deformation process gives rise to failures due to plastic instability, the failure is not necessarily due to insufficient formability of the material. In such cases, FLOs based on constant strain ratio path should not be used directly in predicting the success or failure of the forming operation. Thus the knowledge of forming limits under complex strain paths is of great importance to the interpretation of press-shop problems."

Jan 1, 1994

By Noriaki Kurita, Norihiko Fulcatsu, Teruo Ohashi

"An electrochemical sensing device for hydrogen in molten metal has now been available owing to the development of the proton conducting solid electrolyte made of ceramics of metal oxide. The structure of the sensor and the theoretical limitations of its applications are discussed based on the electrochemical properties of the electrolyte used. The practical performance of the sensor is reviewed from the results of test measurements at the plants of aluminum and copper melting industries. The effectiveness of the sensor to the process control of continuous casting of copper is also discussed.IntroductionSince the in-line monitoring of the amount of oxygen dissolved in molten metal was realized by using the oxygen concentration cell based on zirconia solid electrolyte a similar method has been expected to be developed for sensing of hydrogen, which is a very important element of gas species in liquid metals, especially, in aluminum and copper. In 1981; Iwahara and coworkers found the dominant proton conduction at a high temperature in some perovskite-type oxide (1). Since then, the effort has been made to apply this proton conducting material as the electrolyte of the hydrogen concentration cell for high temperature use. The hydrogen sensor for liquid aluminum of this kind was first produced in 1991 (2) and released commercially from TYK Co., Ltd. Recently, we have developed the mother one usable at higher temperature such as copper and silver melting processes (3). In this note we discuss their structure, design and applicable limitations based on the electrochemical properties of this new type electrolyte. The performance of the sensor and benefit to use it to control the melting process is also discussed"

Jan 1, 2000

By P. A. Davidson

"We discuss the influence of a static magnetic field on jets, vortices and turbulence. This is particularly relevant to D.C. braking in slab casting. Our main conclusion is that, typically, the magnetic field destroys mechanical energy, via joule dissipation, but is unable to destroy momentum. Rather, it continually rearranges the momentum in such a way that the energy falls.IntroductionIt is well-known that a static magnetic field can suppress motion of a liquid metal. That is to say, movement of the liquid across the magnetic field lines induces a current. This leads to Joule dissipation and the resultant rise in thermal energy is accompanied by a corresponding fall in kinetic energy.This phenomenon has been exploited in a range of metallurgical processes. For example, in the continuous casting of large steel slabs, an intense, static magnetic field is commonly used to suppress motion within the mould. The objective is to keep the free surface of the liquid quiescent, thus avoiding the entrainment of surface debris. In other solidification processes, such as techniques for growing semi-conductor crystals, it is widely believed that natural convection has a detrimental effect on the metallurgical structure of the solid. Again, the imposition of a static magnetic field is seen as one means of suppressing these unwanted motions. Finally, magnetic damping is used in the laboratory measurements of chemical and thermal diffusivities, particularly where solutal or thermal buoyancy can disrupt the measurement technique.In this paper we shall look at the damping of jets, vortices and turbulence. Our aim is to present a unified theoretical framework from which the many published studies may be viewed."

Jan 1, 1999

By Zenon R. Llanos

"The disposal of spent hydroprocessing (HDP) catalysts in the petroleum refining industry has been a concern in the past due to their classification as listed hazardous wastes. However, because these catalysts have higher metal concentrations than regular ores, and the recent surge in prices for molybdenum, vanadium, nickel and cobalt what used to be considered as a liability for generators is now viewed as a valuable renewable source of strategic metals. At the same time the generation of spent catalysts has steadily risen due to new environmental regulations for low sulfur fuels and an increased appetite of gasoline consumers. This paper will examine spent catalyst market and the role played by Gulf Chemical & Metallurgical Corporation in the reclamation of metals over the last sixty years. Introduction Hydroprocessing (HDP) catalysts are used in petroleum refineries for two main applications: desulfurization and cracking. The catalyst support is alumina or mixtures of alumina and silica. Active metals include molybdenum, nickel, cobalt and tungsten. The selection of catalysts depends on the application and sometimes the cost. The life cycle of HDP catalysts is represented in Figure 1. The catalyst cycle in a reactor varies from continuous to one-two years. Catalysts used in various refining processes are deactivated by coke, sulfur, vanadium and other impurities in the refinery feedstocks and become spent. Refineries can optionally send the spent catalysts for regeneration, metals reclamation or landfilling. Catalysts used for refining heavy crudes often can not be regenerated. Catalysts used with light oils can be reused twice or three times after regeneration. When the option for regeneration is not viable, spent catalysts are send metal reclamation facilities or landfills."

Jan 1, 2008

By Wang Haibei

China is the important country in terms of Ga, Ge reserves and products. These elements usually associate with lead and zinc ores such as in Fankou, Dachang and Lanping mines. Until now these metals could not be extracted from zinc residues effectively. The main reason is that it is difficult to separate zinc and iron. BGRIMM has carried out considerable research on this subject and some hydrometallurgical processes were developed. Zinc residues were pressure leached with a reducing agent such as zinc concentrates or SO2 at 110~130C. The final concentrate of H2SO4 was 30~50g/L. The metals such as Zn, Fe, Ga and Ge were dissolved into solution. In the leaching residue Pb and Ag could reach 20% and 2000g/t. The feed of solvent extraction was prepared from the leaching solution by pre-neutralization ? precipitation of Ga, Ge and acid dissolving. Then Ga and Ge were extracted by solvent extraction through P204 and G315 produced by BGRIMM. After stripping, metallic Ga was produced by electrowinning. GeO2 was produced by precipitation. The iron in raffinate was removed by the hematite process. The solution after removal of iron came back at the zinc neutral leaching stage. In 2003-2004, pilot tests were finished in BGRIMM in cooperation with Fankou Lead and Zinc Mine Ltd. And the extraction rate of Ga and Ge in the leaching stage was 94% and 83% respectively. The total recovery rate was 90% and 80%. It is estimated that the technology has a wide commercial use in the coming five years.

Jan 1, 2006

By Esa J. Peuraniemi

Copper smelting to form blister in one single step has been possible for a long time even from low grade concentrates. In spite of obvious benefits, it has been economically viable only with few special raw materials having high enough Cu/Fe and Cu/S ratio. Outokumpu Blister Flash Smelting is currently applied at three operations, and three others will be commissioned in the near future. With typical chalcopyrite concentrates two main obstacles have prevented wider adaptation of direct blister processing: slag formation and heat generation. Oxygen potential in the reaction shaft must be high in order to produce blister with targeted sulfur content below 1%. When large amount of iron is oxidized, as well as sulfur, copper is inevitably also oxidized into slag. High copper amount in substantial tonnages of slag lead on to costly down stream recovery operations to obtain discardable slag. Almost complete oxidation of sulfur and iron releases a high amount of heat which traditionally has been solved by lowering oxygen enrichment of the blast leading on to oversized off-gas line and acid plant. One challenge in direct blister smelting relates to the attack of aggressive high-copper containing slag against furnace refractory lining. In continuously operated Outokumpu Direct Blister Flash Smelting this is taken care of by preventing vigorous melt movement in the settler. Stable bath conditions and stationary slag against refractory lining enable the formation of a protective autogenous layer between aggressive slag and vulnerable refractory. These direct blister smelting challenges are addressed from equipment and process development point of view. New solutions to overcome the obstacles are presented and discussed.

Jan 1, 2006

By V. A. Luganov

During the treatment of raw materials containing arsenic and antimony, problems in the distribution of these elements in the process products occur. In a number of cases in processing of copper-bearing materials, it is possible (or necessary) to obtain speiss. The purpose of the present research is to study the theoretical aspects and analyze the technological possibilities of producing copper-bearing speiss and the subsequent electrometallurgical processing with copper extraction as well as arsenic and antimony utilization. Copper arsenide (Cu3As) and copper antimonide (Cu3Sb) are the main components of the speiss. A thermodynamic analysis of the electrochemical oxidation of Cu3As and Cu3Sb, carried out using Pourbaix diagrams, showed that in a pH range from 0 to 2, oxidation potential 0.45-0.55V, ions of copper and arsenic and antimony trioxide are in the equilibrium. The kinetic study has shown, that with an increase in the polarization potential, the dissolution process changes from chemical to diffbsion control. An increase in temperature stabilizes the electrolysis process due to dissolution of arsenic trioxide forming on the anode. Electrolysis of speiss using a cathode diaphragm with the solution pH = 1-2, current density 150-200 A/m2 and temperature 60-70°C makes it possible to obtain cathode copper with a current efficiency of 95-96% and to remove the arsenic from the process during the electrolyte cleaning process. The arsenic content in the cathode copper did not surpass 0.002%. As the result of the research, a technological flowsheet for copper-lead speiss processing was developed. At the present time this technology is undergoing pilot testing.

Jan 1, 1999