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By Sang-Su Lee

This paper shows the application of the porous plug system in the Mitsubishi continuous copper smelting and converting process. This system has already been adopted and utilized in the steel industry to enhance productivity. Recently, some copper smelters have adopted this system but the results have not been satisfactory. The porous plug system was installed at the anode furnace in December 2001 to reduce the oxidation time and decrease the oil consumption. A good effect was that the nitrogen stirring of the melt through porous plugs improved the melt heat transfer. As the result of the enhancing heat transfer the oil consumption and the build-up inside the furnace were actually decreased. But until now the oxidation time has not been sufficiently reduced. In the future, further research and tests are needed in order to increase the productivity and save costs.

Jan 1, 2003

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 Kouji Mimura, Tamas Kekesi, Yongfu Zhu, Masahito Uchikoshi, Minoru Isshiki

"The formation and anion exchange sorption of chloro complex ions can offer a great potential to be utilized for the separation and purification of metals in aqueous solutions. Available stability data were primarily used to estimate the predominance of chloro complex species, indicating the feasibility of such separations. Anion-exchange sorption functions, describing the equilibrium distribution of a number of important elements have been determined by the batch equilibrating method in the practical HC1 concentration range. Various oxidation states were stabilized by the addition of appropriate agents. Tendencies in oxidation, complex formation and anion exchange sorption were confirmed by spectrophotometric investigations. Based on the fundamental results, anion exchange processes have been developed for the purification of iron, cobalt, copper and zinc. The efficiency of separation was assessed and the procedure optimized by the analysis of experimental elution curves. Results have demonstrated that by properly controlling the oxidation states and HC1 concentrations, practically all the impurities can be eliminated. Computer programs have been developed to estimate complex formation and redox equilibria, to screen and correct analytical data, to determine distribution coefficients and to evaluate efficiencies of separation.IntroductionBase transition metals have long been used as the staple materials in various fields of industry. In general, there has been an increasing tendency in purity requirements but recent advances have created a rapidly increasing demand for ultra-high purity metals. To give a few examples, ultra high purity copper can be used as bonding wire and interconnection in integrated circuits, or as material for superconductor stabilizing, high-field magnets, beside its use in cryogenics and ultra high vacuum technology [1]. Iron holds promises as a constituent element in the ß-FeSi2 material to be applied in new opto-electronic devices [2] and it is currently used, together with chromium and manganese, in the production of special magneto-optical materials for digital recording. The use of ultra high purity manganese and chromium in semiconductor technology is evolving. Although not considered a transition metal, zinc is also treated here because of the major significance in compound ZnSe semiconductors [3], and the possibility to purify it by the anion exchange method."

Jan 1, 2000

By Donna M. Noel

Bacterial strains have been cultivated from solids previously exposed to cyanide that will tolerate 300 ppm sodium cyanide under anaerobic conditions. In selected solid samples, these bacteria have been shown to reduce the level of cyanide from approximately 300 ppm to essentially zero in about 50 days under anaerobic conditions. Various media were investigated, and the nutrients providing maximal growth were ?established .. Degradation of cyanide in sterilized solids was determined for comparison with degradation obtained in bioactive solids. All experiments were conducted at ambient temperature and initial pH of approximately 10.5.

Jan 1, 1991

By Andrey Tarasov, Erki Unn, Valery Paretsky

"The stability of the markets of energy resources and labor in countries of the Baltic Sea Region including Estonia is determined to a significant degree by the use of combustible shales as fuel and their distillation resulting in generation of up to 70% of non-recyclable waste. The objective of this business plan is to substantiate the investments for establishment of a new facility in Estonia for waste-less and environmentally safe processing of fossil minerals and man-made products generated in the shale industry, as well as other hazardous wastes. The proposed facility will use a basically new waste processing technology developed in Russia - i.e., processing in sparged molten slag This technology eliminates any release of harmful pollutants to the environment and a facility using this technology does not require, therefore, any sanitary protection zone.IntroductionIn the Baltic region, and first of all in Estonia and some other European territories, there are large natural deposits of combustible shale, which due to the lack of other own resources of energy and hydrocarbons for the chemical industry is burned and distilled with low technical and economic efficiency generating large amounts of toxic and highly toxic wastes and intermediate products. Currently, the penalties for disposal of such wastes have grown to such an extent that shale burning and distillation might become unprofitable. This might result in suspension of the given operations, which in turn will affect in an adverse way the markets of energy resources and labor market in those countries. Furthermore, in addition to the “shale problem”, Estonia, similarly to most member countries of the European Union, faces the challange of environmentally safe processing of highly toxic wastes, such as municipal solid wastes, oilpolluted materials, medical wastes and infected materials, spent rubber tires, etc. These wastes are at present stored or processed with release of a significant quantities of extremely toxic cancerogenic substances (dioxins, furans) or collected and exported for treatment at an extremely high cost and with a loss of valuable components contained in these types of waste and often with return of supper toxic processing products."

Jan 1, 2008

By A. H. -J. Siegmund

Since the last survey of lead smelters in 1987, the lead industry has experienced many changes. Technological innovations, in combination with a dramatic shift in the market structure as well as more stringent government regulations, caused major upheavals in many different areas. Therefore, a new survey was performed to review the progress in the technology of lead recovery over the least decade. The newly conducted survey reflects all current phases of the world's primary lead production, from charge preparation to refined metal shipment. It was prepared by sending questionnaires to individual companies, and the detailed statistical data of this survey are presented. In considering the data developed from the survey, it should be recognized that the primary lead industry is at a crossroad where novel technologies will gradually substitute the sinter machine - blast furnace operation in the new millennium.

Jan 1, 2000

By D. C. Foguel, J. L. R. Bravo

For several years, Caraiba Metais S.A. (CMSA) had to stock the arsenic sludge generated from the electrolyte purification process of its tankhouse. The amount stocked · reached approximately 3,500 tonnes, as the effects of its recycling during the smelting process and consequently in the sulfuric acid plant were unknown. Besides, it had as limiting factors the high content of arsenic in the copper concentrates supplied by foreign countries as well as the reduced capacity of the tankhouse's purification plant. The choice for selling the mentioned residue, which generally contains more than 50% of Cu, was attractive, but the environmental policies and regulations had not allowed this option. Other alternatives, such as the production of bicupric arsenic by means of a solvent extraction process or arsenic trioxide, were considered but the economic feasibility was not attractive due to the absence of a domestic market and a poor international market. After a study of the arsenic partition in the metallurgical process, it was verified that the residue could be recycled without causing any operational problems or damage to the environment. To make this possible, the capacity of the purification plant was increased and the way of removing the arsenic sludge from the cells was modified from manual to mechanical, therefore avoiding the direct contact of the workers with this poisonous substance. Moreover, procedures for recycling in the smelter were established and tolerance limits were set for both the smelter and the sulfuric acid plant. The main amount of arsenic to be recycled is released with the smelting furnace off-gas, which is washed during the purification stage of the sulfuric acid plant. The acid water, rich in arsenic, is then treated in the waste plant and the arsenic, in its stabilized condition, is confined in an appropriate area.

Jan 1, 2000

By Gaifeng Xue, Lei Zhang, Aimin Duan, J. Y. Hwang, Lina Wang

"The removal of chemical oxygen demand (COD) from coking wastewater was experimentally investigated using a three-dimensional electrode reactor. The experimental results showed that the refractory organics in coking wastewater can be effectively removed by this process, and COD removal efficiency was affected by the operating parameters, such as electrolytic retention time, particle electrode dosage, initial pH, current density, aeration amount and electrical conductivity. The experimental results show that the three-dimensional electrode could have a COD removal efficiency of more than 60% and a running cost of no more than 6 YUAN (RMB)/t. This indicates the great potential of a three-dimensional electrode reactor in engineering applications as an advanced treatment methods for coking wastewater.IntroductionCoking wastewater is generated from coal coking, coal gas purification, and by-product recovery processes of coking; it is composed of phenolic compounds, heterocyclic compounds, polycyclic aromatic hydrocarbons, ammonia, cyanide, polycyclic nitrogen-containing aromatics, acyclic compounds, etc. Most of these constituents are refractory, poorly biodegradabile, toxic and carcinogenic [1-3]. Currently, coking wastewater is usually treated by different forms of A/O biological nitrogen removal processes as the primary treatment means, but the aforementioned processes are not efficient enough to meet the requirements of the National Discharge Standard in China (GB13456-1992). According to the continuous requirement on improving environmental protection for the coking industry (revised 2008), increasing wastewater utilization ratios and reducing the discharge of effluent in the coke industry have to be implemented for cleaner production and sustainable development. Therefore, advanced technologies need to be developed to treat coking wastewater and reutilize the product as industrial cooling water, which would be one of the best choices to achieve zero discharge of wastewater and reduce water consumption per ton of steel produced. In this study, a three-dimensional fluidized bed electrode reactor was adopted for the advanced treatment of coking wastewater, and the effects of operating conditions, including particle dosage, initial pH, current density, supporting electrolyte, as well as aeration amount on the COD removal rate, were investigated. Its running costs were also estimated."

Jan 1, 2012

By Robert M. Leary

The Kennecott Utah Copper smelter operates two Outokumpu flash furnaces: a smelting furnace for production of high-grade matte and a converting furnace for production of blister copper. Flash furnaces typically possess several characteristic features that must be considered in process control development such as long lag times associated with settler volume, non-linear input and output responses, large process gains, and unmeasured disturbances. Additionally, the Kennecott smelter possesses certain unique characteristics which must be considered such as single mine concentrate source, limited concentrate blending capacity, and feed preparation facilities that inevitably cause significant lags between furnace control parameters and manipulated set points. In order to improve furnace control and on-line time, a process control system was developed to address these issues. The feed forward control module provides predictive control and operates in response to furnace feed input changes. The feed back control module provides responsive control and is based on furnace output deviations. To provide regular feed back information to the control room supervisors, new sampling methods were developed which provide the operators with molten metal and bulk material samples at regular intervals to provide information for control. The control system was implemented on the Flash Converting Furnace in May 1999 and on the Flash Smelting Furnace in August 1999.

Jan 1, 2000

By W. P. lmrie

The recent years have seen many copper smelting operations become uneconomic due to a combination of low metal prices, high energy and labor costs, environmental requirements and high investment costs for modernization or replacement. Since a copper commodity requirement remains, the industry will recover, but many operations will need to determine which processes can offer the best prospect for economic operation and readiness for reliable investment and implementation. Corporate investment decisions involve the judgment of many factors in addition to topical technical aspects. Consideration of plant management and operational aspects are thus included. Taking account of such proven processes as conventional, flash and continuous smelting, plus modified conventional and new unproven processes, this paper gives a systematic approach to aid optimum choice for a modernization or grassroots investment. Actual achievements in energy form alternates, conservation and cost effectiveness are highlighted, and areas of remaining potential for energy saving are discussed.

Jan 1, 1983

By Yan Beygelzimer, Alexander Spuskanyuk, Victor Varyukhin

"The main idea of the report is that the yield surface can be presented as thick, ""foamed surface"" with dimensionality exceeding two. By other words, perhaps, the yield surface is fractal, i.e. it belongs to the class of geometric objects with fractional dimensionality. Apparently, fractal structure of the yield surface is determined by the fractal structure of natural materials. ""Cloud of internal stresses"" term is introduced to describe the stress distribution in representative volume element. Its plastic flow is determined by the interaction of this cloud with the thick yield surface. Thick yield surface and internal stress cloud concepts allow to determine an additional correlation between micro mechanical models of polycrystals and phenomenological theory of plasticity.1. IntroductionClassical plastic flow models are not satisfying the modem requirements. There are two main directions in their development. The first, mathematical, is connected with the development of the general theory of rheological relationships; the second, physical, is connected with the development of the representative volume element (RVE) models which are based on specific ideas about deformation mechanisms. Within the framework of the first direction, the macroscopic experimental data is formalized; the second approach deals with the generalization of physical research results for the different scale levels that are involved in plastic deformation.These approaches have advantages and disadvantages. In phenomenological theories, the advantages are the mathematical simplicity and laconic formulation of constitutive relations, which allows using them in practical calculations. However, the mathematical models of this class can not be considered as general, they are useful only for the description of limited range of deforming processes. On the other hand, physical theories that are based on the description of real plastic deformation mechanisms are very explanatory and predictive, but they lack mathematical simplicity. The above circumstances lead us to the necessity of compromise that can be found in determining the constitutive relations for RVE, which structure and parameters would bear the information about rnicrolevel and mesolevel phenomena. In this synthesis direction, the fundamental role belongs to [1,2], etc."

Jan 1, 2001

By Travis Knight

Mixed uranium and refractory metal carbide systems have been proposed for space nuclear power and propulsion applications. Solid-core space nuclear reactors could be utilized for low- earth-orbit (LEO) to geosynchronous-earth-orbit (GEO) transfers, manned missions to the moon or mars, and orbiter missions to the outer planets. However, these high performance space nuclear reactors present some challenging materials engineering requirements for operating in a high temperature, high radiation, and hot hydrogen environment. Since the RoverNERVA programs were concluded in 1973, significant advances in ultrahigh temperature materials technology have been made which can be applied to the development of an advanced solid-core nuclear fuel. Nuclear thermal propulsion (NTP) was first studied in the U.S. beginning in the mid-1950's during the RoverNERVA programs. During that time, about 20 rocket reactors were built and tested. More recently, Russian nuclear rocket reactor tests with pseudo-ternary carbide nuclear fuels (U, Zr, Nb)C and (U, Zr, Ta)C have been operated at temperatures as high as 3300 K for one hour. This study examined the processing parameters for fabricating the pseudo-ternary carbide, (U, Zr, Nb)C.

Jan 1, 1999

By Suswnu Makino

Sumitomo Metal Mining developed a new nickel refining process ( Matte Chlorine Leach Electrowinning process) based on chlorine leach and electrowinning technologies. After the pilot plant study, the commercial plant with design capacity of 24,000 tonnes per year was constructed and has been successfully operated since August, 1992. During the practice of the past three years, great deals of improvement have been achieved. Through these operations the MCLE process has been demonstrated to be one of the most superior processes in the world with nickel recovery, productivity, cathode quality and working environment. Today the refinery product capacity is increased to 30,000 tonnes per year. This paper describes the equipments and operation of the Sumitomo MCLE process.

Jan 1, 1996

By Julien Favre, Akihiko Chiba, Damien Fabregue, Yuichiro Koizumi, Eric Maire

"The mechanical behavior of Co-20Cr-15W-10Ni alloy is studied by compression tests at high temperature. Microstructures after deformation are evaluated using SEM-EBSD. Significant grain refinement occurs by dynamic recrystallization for high temperature and low strain rate (T>1100°C, <0.1s-1), and at high strain rate (~10s-1). Dynamic recrystallization is discontinuous and occurs by grain boundaries nucleation, leading to a necklace structure. The nucleation mechanism is most likely to be bulging of grain boundaries. However, recrystallization occurs also by rotation of annealing twins which can bulge as well. The modeling of mechanical behavior gives a fair quantification of flow softening due to dynamic recrystallization, indicating the progress of dynamic recrystallization with deformation.IntroductionCobalt-chromium alloys are used in biomedical applications for the elaboration of implants due to their outstanding mechanical properties and their high resistance to corrosion. For stent application a large ductile behavior is required in addition to the high mechanical strength. Indeed stents have to undergo a deformation until e˜40% during their expansion [1]. Conventional Co-Cr-Mo (CCM) alloys exhibit limited ductility (maximal deformation about e˜30%) [2]. Co-Cr-W-Ni (L-605) alloy is a better candidate for stent elaboration since its fracture strain can exceed 40% (comparable to nickel superalloys (Figure 1), while it keeps high mechanical strength. In spite of the presence of nickel element in this alloy, biocompatibility is sufficient for vascular implants, therefore L-605 alloy is extensively used for heart valves and stent elaboration [3]."

Jan 1, 2012

By R. M. Nadkarni

This paper examines the broad&apos; economic parameters of copper smelting by conventional and new smelting technology. Location, transportation of products to market and pollution control options are discussed.

Jan 1, 1983

By Jan G. H. du Preez, C. Viviers, B. J. A. M. van Brecht, H. E. Rohwer, Nicole M. Sumter

"At the basis of metal ion separation lies some particularly metal ion specific chemical property which lends itself towards exploitation. This could be in the form of an anionic complex or a neutral chelate complex. In the former a cationic centre with a particularly high affinity for the complex will have to be designed. In the latter case a stereospecific chelate ligand containing the correct symmetry and type of donor atoms will have to be designed. In both above cases the ""active centre"" can be entered in a from that it can function in different media of hydrophobicity, eg a precipitant, a resin or a solvent extractant. Recent results obtained in this laboratory will be used to illustrate how the above variables can be exploited to develop improved processes for the separation of base metal and platinum group metals.IntroductionThe separation of metal ions in hydrometallurgy can be performed broadly speaking with two major aims. Firstly the separation/removal of a certain group of metal ions, either as a means of preconcentration or as a removal from effluent as part of a purification process and, secondly the removal of a specific metal ion from an industrial stream in order to produce a specific metal in a pure form. This latter operation is by far the most difficult of the two and is becoming more so in the light of the fact that the world is moving in the direction of lower grade ores and increasing pollution. Such a process can be divided into three essential parts, firstly the molecular one in which an active centre is required to obtain specificity, secondly a matrix within which this active centre must function, i.e. as part of a resin or solvent extractant and thirdly the design of the total system to optimize the realization of the operation."

Jan 1, 1996

By Richard Elliott

Current methods for producing low-carbon manganese alloying materials for the steel industry are energy intensive and costly. To enable wider implementation of high Mn steel alloys, a novel solid-state Mn ore reduction strategy is therefore being investigated. This solid-state process, modelled on existing Direct Reduced Iron technology, employs a methane-containing atmosphere to reduce Mn ore pellets to a metal carbide. These pellets may then be smelted, yielding a Mn-rich master alloy. It is well established that CH4 is a suitable reductant for Mn ore powders; however, the reduction behaviour of industrially relevant Mn ore pellets by CH4 is poorly understood. The present work reports the results of an investigation undertaken to address this knowledge gap. The results of this study highlight the significantly different reduction behaviour exhibited by the Mn ore pellets relative to the ore powder under similar conditions and suggest that the diffusion of CH4 into the pellet interior is the limiting factor in achieving complete reduction.

By Saskia Duyvesteyn

Small ion-exchange resin particles provide faster mass transport than conventional-sized beads. Unfortunately, high pressures are needed to pump solutions through columns containing small resin particles. It is preferable to disperse fine resins in the solution being treated. Screens have been used to separate the resin from the solution, but screens do not retain fines created by attrition of the resin particles. We have developed a separation process based on flotation, which relies on the surface characteristics of the resin, instead of size. The resin is conditioned with a surfactant before dispersing it in the solution to be treated; this increases the hydrophobicity of the resin sufficiently for froth flotation, without introducing surfactant directly into the solution. The surfactant adsorbed on the resin surface does not appear to impair the kinetics of metal ion removal. A flowsheet for an effluent treatment process is proposed; other applications are clearly possible.

Jan 1, 1998

By Vanessa M. Torres

Cia. Vale do Rio Doce is currently developing Niquel do Vermelho Project. The laterite deposit is located at Carajas Mineral Province at less than 15 km from Sossego Copper Project, scheduled for start-up in 2004. The available infrastructure, includes paved roads, large capacity railroad and port complex owned by CVRD, power supply and good quality water. The project was evaluated in the past for ferronickel production. In the late 1990s, CVRD switched its attention to investigating the usage of pressure acid leaching. The combination of good metallurgical behaviour for pressure acid leach (PAL) process route with reasonable mineable grades, and existing infrastructure justified the start of engineering studies in 2002. The project approach at the engineering phase is based on the dual objective of minimizing risks while maximizing project profitability and value. CVRD is currently completing the Niquel do Vermelho prefeasibility study. This paper outlines the main outcomes of the study and future perspectives for the project.

Jan 1, 2004

By Arthur S. Klein, Hugh R. Lowry

"The Levitation Casting Process is a new continuous casting method that uses an electromagnetic levitation field, instead of a mold, to support and contain a column of solidifying metal. By counteracting gravitational forces and hydrostatic pressure on the metal column, this process eliminates friction and adhesion at the interface between the solidifying metal and the cooled walls of the casting chamber. The process inherently provides high casting speeds, excellent dimensional control and smooth, continuous emergence of solidified product from the top of the casting chamber.Of major importance is that the electromagnetic field produces an intense stirring of the liquid metal both before and during solidification. As a result of this stirring, the cast product has a homogeneous, equiaxed, fine grain structure generally suitable for immediate drawing or other forming operations without the need for hot rolling or other expensive additional processing.This paper reviews the fundamentals of the Levitation Casting Process, results obtained in casting various pure metals and alloys, and the production sized system at Lowell, MA, that uses this process. IntroductionThe Levitation Casting process was specifically developed to meet several requirements including:• Economic at low casting rates• Usable with pure metals and alloys• High, uniform product quality suitable for fine wire drawing or cold rolling into flat strip and tape• Easy cast product shape and size changes• Process inherently stable and easily automatedIn meeting these criteria it was also desired to retain the advantages of General Electric's well known Dip Forming continuous casting process; namely the inherent ""fail-safe"" properties of upward casting, solidifying metal by means other than pressure contact with a cooled mold, and use of a sealed furnace, casting chamber and cooling tower, filled with a protective atmosphere, to prevent oxidation of the molten metal or cast product."

Jan 1, 1988