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By M. S. Moats

The treatment of oxidized residues of zinc with high iron content continues to present a technical challenge in both the steel and zinc industries. Two main problems are commonly identified and include high treatment costs and environmental concerns about contaminated, iron-bearing residuals. A new approach to this problem is described in which selective separation of the iron and zinc into salable products may be potentially feasible. The waste material is first leached to give a solution having an approximate concentration of 110 g/l Zn, 15 g/1 Fe and 40 g/1 H2SO4 and other impurities such as Pb, Cd, Cu and Sb. A suitable organic, such as D2EHPA, is used to load the majority of the iron. The aqueous phase is then acceptable for zinc electrowinning after standard solution purification. The novel step in the flow sheet is the efficient recovery of the ferric iron from the organic solvent using a solid metal to reduce the iron to the ferrous state. The Fe+2 is easily stripped into an aqueous phase in a relatively pure form, suitable for use in water treatment. Process parameters and possible flow sheet designs are described and discussed.

Jan 1, 1995

By Liang Wang, Sheng-Kai An, Bing Xie, Hong-Yi Li, Cui Li

In order to develop an environment-friendly method for extracting vanadium effectively from aqueous solution containing vanadium, the dynamic adsorption behavior of V by a continuous fixed-bed column which was filled with macro-porous weak base anion exchange resin was studied. Effects of conditions including the bed depth, flow rate, concentration of vanadium ions on dynamic V adsorption were investigated. The optimum adsorption conditions were established at flow rate of 6 ml/min with bed depth of 20 cm. Isotherms studies demonstrated that the column adsorption of V was a favorable chemical ion exchange process in monolayer. Several kinetic models were applied to analyze the adsorption characteristics. Analysis results of the Bohart-Adams model indicated that the adsorption process was dominated by external mass transfer in the initial stage. The Thomas model was appropriate to describe the column behavior, revealing that both external and internal diffusions were involved in the limiting steps.

Jan 1, 2014

By Yousef Mohassab, Hong Yong Sohn, Mohamed Elzohiery

As part of the development of a novel flash ironmaking process at the University of Utah, a labscale flash reactor was used to produce iron directly from iron oxide concentrate. This work tested the feasibility of the novel flash ironmaking process using the partial combustion of hydrogen as fuel and reductant. In this flash reactor, the energy required to reduce concentrate particles was obtained from the internal combustion of hydrogen and oxygen with complementary energy from electrical resistance heating to compensate for the heat loss. After the reaction shaft was electrically pre-heated, hydrogen and oxygen streams produced a non-premixed flame inside the reaction shaft. Various conditions such as flame configuration, flame power, positions of concentrate feeding ports, excess hydrogen amount and residence time were tested. More than 90% reduction of magnetite or hematite was achieved at temperatures as low as 1175 oC with < 100% excess hydrogen in <10 s of residence time.

Jan 1, 2016

By Maneesh Singh

During the various stages of iron & steel production a number of iron-rich by-products are generated. The traditional way to recycle them back to the blast furnace has been the balling - sintering process. These by-products can also be made into cement-bonded agglomerates for use as burden material for blast furnaces. In order to improve the quality of agglomerates the effects of various processing parameters on the properties of cement-bonded briquettes have to be controlled. This paper looks into the various aspects of producing cement-bonded agglomerates and using them as burden material for blast furnaces.

Jan 1, 2003

By C. H. Tsau

The intermetallic compounds of Ni-25Al-xFe, x is 20-40 at.%, were prepared by arc melting and drop casting into ingots, and were rapidly solidified into ribbons by melt spinning. The microstructure evolution of these alloys with varied Fe content were examined by the x-ray diffraction, optical microscope, scanning electron microscopy and transmission electron microscopy. The results reveal that two phases, {y&apos;} and {B} phases, are existing in the alloys with low Fe content, and the microstructure changes from the mixture of y&apos; and {B} phases to a single 0&apos; phase when the Fe-content reaches to 40 at.%. Also, the formation of y&apos; phase will be suppressed by rapidly solidified process. For annealing both of the melt-spun and the cast specimens, a disorder 0 phase was revealed in both of the ribbon and the cast ingot of Ni-Al-Fe alloys with higher Fe content. In addition, increasing the increment of iron which substituting nickel in this alloys results in increasing the lattice parameter of both {y&apos;} and{B} phases.

Jan 1, 1992

By William A. Apel

Several different strains of bacteria have been shown capable of reducing hexavalent chromium, Cr(VI), to Cr(III), a less toxic, .. more readily recoverable form of Cr. This paper examined the Cr(VI) reduction efficacies of 3 different Cr(VI) reducing bacteria: Pseudomonas f1uorescens LB300., Pseudomonas aeruginosa PAOI, and Pseudomonas aeruginosa PAOI (pCROI) It was demonstrated that all three bacterial stratns reduced Cr(VI) primarily during their exponential growth phases while using glucose as their carbon and energy source. Significant differences in the three organisms&apos; Cr(Vl) reduction capabilities depending on initial Cr(VI) concentrations were also demonstrated. P. aeruginosa PAOI showed superior Cr(VI) reducing capabilities over the. entire range of Cr(VI) concentrations tested while the Cr(VI) reduction capabilities of the other two strains were increasingly inhibited as Cr(VI) concentrations increased.

Jan 1, 1991

By Norbert L. Piret

From the copper smelter operation a various outputs are to exert negative impacts on the environment. Particularly, emissions like SO2 and dusts, solid wastes like contaminated gypsum and arsenic sludge, effluents and heated cooling water are generated. Most countries have sitipulated an environmental legislation to provide the framework for an efficient environmental management. As part of the planning activities for x major greenfield copper smelter, the Following elaborations are required and were drawn up. -The Environmental Impact Assessment which is the first step of environmental management and mandatory for every new project. - The Environmental Monitoring Plan, which describes the monitoring procedures for the main impacts identified and assessed. -The Environmental Management Plan, which deals with the minimization of environmental impacts, and the methods of its implementation.

Jan 1, 1996

By Michael F. Kitto

The production of sulphuric acid at base metals smelters is predominantly an involuntary activity and now comprises approximately 17% of all-forms sulphur supply in world terms. The majority of elemental sulphur is also produced involuntarily in response to environmental regulations regarding emissions from hydrocarbon processing plants. The paper examines the points of similarity and difference in the sulphur and smelter acid markets, and reviews their interactions. The reasons for the merchant acid market collapse of 1993 are analyzed, and the prospects of a recurrence are considered.

Jan 1, 1996

By J. B. Vander Sande, I. G. Solórzano, B. S. You, P. M. Jardim, W. W. Park

"Alloys with six different compositions in the system Mg-Ca-Zn were produced by melt spinning. The aging behavior of alloys was investigated by measuring the changes in microhardness after isochronal aging and the microstructure was analyzed by means of transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), scanning transmission electron microscopy (STEM) and scanning electron microscopy (SEM). All six compositions in the as-solidified condition show a difference in microstructure between the wheel contact side (zone A) and the free surface side (zone B) as a result of the differences in the solidification rate across the ribbons. One of the alloys (Mg-l.5wt%Ca-6wt%Zn) was chosen to be more deeply investigated in this work as it exhibited grain boundary films and an age hardening behavior was produced in that alloy.IntroductionMagnesium is the lightest of all the commonly used metals, and very attractive for applications in transportation. It also has a number of other desirable features, including good ductility, better damping characteristics than aluminum, and excellent castability. However, there are some negative features, such as high reactivity in the molten state, inferior fatigue and creep resistance as compared to aluminum, poor corrosion resistance and high production cost.In recent years there has been a significant increase in magnesium use as a structural material. These structural applications include aerospace, automotive and nuclear industries as well as appliances and sporting goods (1 ). According to reports on Mg-Zn alloys, the addition of Zn (2) in magnesium increased strength. Also, since the maximum solubility of Zn in magnesium is 6.2wt%, a considerable amount of Zn can be retained in solid solution in magnesium alloys by rapid solidification. In addition, Ca is known (3) to be one of the most potent alloying elements for refining the microstructure and precipitates in magnesium alloys, and also to improve mechanical strength and corrosion resistance."

Jan 1, 2000

By Keith Cramer

As a leader in the development of metal extraction technology, Avecia continues to pioneer advancements for the processing of copper through leach, solvent extraction, and electrowinning of copper. From the initial patent of the second generation of oxime 5- nonylsalicylaldoxime in the 1970&apos;s; to the effective use of modifier technology; and development of computer assisted modeling programs, Avecia is driving SX technology to maximize extraction productivity. Keys to consider when advancing productivity are: 1) high quality, high performance products; 2) a responsive, partnering approach to technical service; and 3) tools to aid in the education of industry wide technical personnel with a view on continuous improvement. The focus of this paper is on the advancement of tools to aid in the education for optimization of processing copper through solvent extraction. One such tool is Avecia&apos;s own customized solvent extraction modeling program called MEUM. MEUM is currently used world wide to analyze plant operations, test ideas for improving operations, assist engineering companies in design, and to teach basic solvent extraction concepts. Recently MEUM has also been incorporated into a University setting. In the spring of 2000 Avecia worked with the University of Melbourne to integrate MEUM into their Mass Transport tutorial class. Students completed exercises to evaluate how operational changes affected a solvent extraction plant&apos;s performance. This paper introduces the basic functions of the program and discusses the successful implementation of MEUM into the University of Melbourne curriculum.

Jan 1, 2002

By P. C. Guillaume

Global plant modernizations or expansions cannot be considered in the same light as any other industrial investment project. Relationships between the partners, relationships and communications with the client, structure and organisation of the teamwork, schedule of the work, and a lot of other tasks and missions devoted to external contractors have to be defined considering one fundamental input: an operating plant. For an engineering company expert in processing, like UM Engineering, such a context requires a specific approach as well as specific procedures able to efficiently challenge the generated constraints. First of all, even if a detailed audit had been conducted at the beginning of the conceptual engineering phase, new elements will be discovered during the preparation and realization of the project, and must be continuously integrated. Consequently, a close proximity to the site is necessary. This is one reason why UM Engineering, most often, works in partnership with a local engineering company. The second important point for the client is that the operation must not be interrupted during the realization. In order to make that possible, UM Engineering has defined a specific project structure and organisation, integrating on a permanent basis the operators (the "users") in the project teams. This paper presents the way UM Engineering copes with this type of "multi-constraints" context with reference to the recent copper cellhouse modernization under realization for the CCR Refinery of Noranda Inc. in Canada.

Jan 1, 1999

By Karen Tempel

Newmont&apos;s Lone Tree Mine is located 30, miles east of Winnemucca in Humboldt County, Nevada. Starting in February 1994 a pressure oxidation circuit was commissioned to treat refractory gold ores. Gold is leached and recovered from the oxidized slurry in a six-stage carbon-in-leach (CIL) circuit. Lone Tree has been able to maintain tighter control&apos; of cyanide addition and reduce cyanide consumption its CIL circuit through the installation of Degussa&apos;s Cyplus® CCS Cyanide Control System in the spring of 2000. &apos;The Cyplus® CCS, along with additional inputs&apos; from plant sensors, has allowed tor a more efficient and effective control strategy over the manual control method used ,in the past. This paper documents the key aspects of the Cyplus® CCS installation; the development of the control strategy, and the benefits achieved from enhanced control.

Jan 1, 1998

By René Winand

The paper gives a synthesis of research work performed in the department during the last ten years and dealing with cobalt , copper and manganese electrodeposition in chloride aqueous solutions. Special emphasis is given to electrocrystallization. For copper, properties of the electrolyte such as solubility limits, electrical conductivity and complex ions stability are discussed in connection with leaching, purification of the electrolyte, and metal recovery. When possible, kinetic parameters and probable electrode mechanisms are given. Problems that are still to be solved are also listed.

Jan 1, 1985

By Toshihiko Emi

The quest for cleaner steel is driven by increasingly stringent requirements from the manufacturing and construction industries. Key issues are the occurrence and removal of inclusions; These are discussed in the context of the unit processes of deoxidation, refining, transfer and casting of molten steel. Process thermodynamics and kinetics are also discussed. Recent progresses achieved and problems yet to be solved are elaborated, and an integration of the unit processes into a system to produce extra clean, steels with better performance is presented.

Jan 1, 1999

By Takahiko Okura

Japanese non-ferrous industry introduced large-scale smelting plants along seashores for overseas concentrates with increasing demand of metals around 1970s. Although serious environmental pollution became obvious, with economic growth, the industry got rid of pollution by installing new processes and improving operation technologies. At present, over 99.8% of sulfur input to smelters is fixed as stable compounds. Through those decades Japan had steep rises of oil prices, sudden change of exchange rate, and inadequate treating charges, we were faced to consider the closure of smelters. The industry has survived by increasing productivity, saving energy and reducing manpower. Furthermore the industry made great effort to recycle valued metals from scraps and wastes for the resources-recycling society. Academic research also contributes to support these individual technologies. Thus the industry has fostered world-acclaimed technologies in terms of efficiency and energy conservation. This paper presents technology development and environmentally-benign sulfide smelting processes.

By E. Saez, M. Bellet, T. Coupez, O. Jaouen

"The paper presents a 3D finite element solver for non-steady state fluid flow. The thermomechanical simulation package REM3D® has been initially developed to model Stokes' flow for polymer injection. The mechanical module is based on a Eulerian velocitypressure formulation. The spatial discretization uses P 1+IP1 tetrahedral elements. The front tracking module consists of the resolution of a transport equation, thanks to a space-time discontinuous Galerkin formulation. It includes mesh adaptation, which permits a dynamic refinement at the front, thus controling the numerical diffusion. The same approach is used to solve heat transfer. In this paper, we focus on the specific adaptations done to treat Navier Stokes flow. The treatment of inertia is detailed, as well as the implementation of sliding conditions at mould surface, using conservative normals. Industrial applications are presented.IntroductionThe study of the mould filling stage in casting processes requires the ability to simulate complex non steady-state three-dimensional flows. Most commercial software use the volume of fluid (VOF) method, associated with a Eulerian formulation, see for instance the series of conferences ""Modelling of Casting, Welding and Advanced Solidification Processes"" [1-3]. The VOF method [4] consists in solving the conservation equation dF / dt = 0 for a variable F - the volumic fraction of fluid - whose value is 1 in filled regions and 0 elsewhere. Two fluids are actually considered: the molten alloy and a gas in the empty regions. This method suffers generally from numerical diffusion in the resolution of the free surface tracking equation, which is of pure advective type. The precision of the computation is then strongly dependent on the mesh density. Since the mesh is fixed (Eulerian formulation) this implies that in case of complex flow the user must have a priori a fairly good idea of the flow characteristics in order to capture properly the critical features of the flow. In addition, the method can hardly handle the discontinuity of the material viscosity at the interface. To prevent this difficulty, the viscosity value is smoothed around the interfuce, adding once again some inaccuracy. Since the value F = ½ is supposed to represent the free surface, it results in a smeared fluid surface. An alternative to the fixed mesh methods are the methods in which the mesh covers the fluid domain only, as proposed by Navti and Lewis [5-6], or Gaston and Bellet [7]. Based on updated Lagrangian schemes, they must be associated with an ALE formulation (arbitrary LagrangianEulerian) in order to reduce the number of full remeshing operations."

Jan 1, 2004

By Peter Willbrandt

The flash smelter at NA was commissioned in March 1972 with an initial throughput of 50 tons of dry copper concentrate per hour. As a result of various measures, for example, oxygen enriched process wind, extension of the radiation part of the waste heat boiler, etc., the throughput could be increased to the present 70 tons per hour of dry concentrate. NA&apos;s plant is located on the outskirts of the city of Hamburg. The flash smelter&apos;s location and the growing awareness of the German population as regards environmental issues necessitate again and again considerable capital expenditure being spent on environmental protection. Thanks to the numerous small and large measures taken to protect the environment the emissions of dust, heavy metals such as arsenic, copper, lead, etc., and as well SO, could be drastically reduced. This paper will be giving an overview on the present state of the flash smelting process and the impact of the increasing environmental awareness at NA.

Jan 1, 1993

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 Luben Savov

This paper presents recent research works on the removal of the tramp elements Cu, Sn, Zn and Pb from steel. The evaporation of Cu and Sn in iron-based melts treated at reduced pressure of the gas phase was studied in a vacuum induction melting furnace. The effect of chamber pressure, temperature and melt composition was investigated. Since the main source of contamination of steel with Sn and Zn is the recycling of tinplate and zinc coated steel, respectively, possibilities for the removal of meta1ic coatings in a scrap pre-treatment stage were studied, too. Tin was removed in the temperature range 400-5S0°C by treatment with reactive gases featuring high sulphur potential. Zinc can be removed by evaporation or by a combination of thermal and mechanical treatment. The paper discusses the thermodynamics of Pb in carbon-saturated iron melts, too.

Jan 1, 2001

By P. S. Arthur

The ISASMELT? process is a submerged lance smelting technology operating in smelters in Australia, the USA, Belgium, India, Germany, Malaysia and China. Further plants are under construction in Peru and Zambia. Following the invention of the Sirosmelt lance technology Mount Isa Mines recognised the commercial potential in the novel top blown bath smelting process and embarked on a development program that has lasted more than 25 years. After successful operation of pilot plants and demonstration plants producing copper and lead, Mount Isa Mines decided to license the technology to external companies. Since the purchase of Mount Isa Mines by Xstrata in 2003, Xstrata Technology has assumed responsibility for transferring the technology to ISASMELT? licensees. In the 15 years since the first commercial furnaces started operation plants have been constructed (or are under construction) with a combined annual smelting capacity of more than six million tonnes of concentrates or secondary raw materials. Process development continues on the commercial scale plants at Mount Isa and elsewhere. Many of the improvements implemented by plant operators have been passed on to, and adopted by, other licensees. Exchange of ideas and technical improvements occurs through ad hoc visits to fellow licensee sites and through regular licensee workshops arranged by Xstrata Technology. This paper updates the reader on the status of various ISASMELT? plants either operating or under construction. It highlights the important role that the technology provider?s operational experience plays in ensuring that new smelting plants ramp up quickly to nameplate capacity.

Jan 1, 2006