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By Fumito Tanaka

The Converting Furnace (C-furnace) of the Mitsubishi process has solely provided opportunities for producing blister copper continuously from molten matte. Continuous converting originates from the proven technology for controlling the behavior of magnetite in lime-ferrite slag of the CaO-FeOX-Cu2O system. Recent improvements in the C-furnace operation have included the slag controls reflecting the impact of minor oxides on magnetite behavior. Although previous investigations focused on magnetite behavior, sulfur has also affected the C-furnace operation because it is of practical importance to avoid the precipitation of gypsum from lime-ferrite slag and the separation of matte from blister copper. This paper will quantify the behavior of sulfur in C-furnace with respect to the gypsum formation and matte separation, and discuss better controls for C-furnace operation.

Jan 1, 2006

By Clara María Lamus Molina

The following minerals found in the residual black sands from gold mining in El Bagre Antioquia (Colombia) were identified as having major economic interest: Ilmenite (FeTiO3), with an average of 49% of TiO2, frequently altered presenting crowns; lamellaes of rutile and alteration textures; titanomagnetite with up to 25% of TiO2; magnetite (Fe3O4) in individual grains or associated with others minerals as hematite and ferromagnesian silicates rutile (TiO2) with considerable quantities of Nb2O5(0.1-3.7%Wt); zircon (ZrSiO4) with 66%Wt of ZrO2 and monazite with an average of 63.43%Wt of REE, this frequently associated to xenotime and thorite forming textures as little drops. Analysis in EPMA and SEM/EDS showed percentages of minor elements and traces, thereby clearly establishing the applications of these minerals in diverse industries. Furthermore, a detailed granumetric study of the different minerals and textural relationships among them also allowed for establishing the basis for possible processing and exploitation.

Jan 1, 2006

By Gabriel Riveros, Ariel Balocchi, Andrzej Warczok, Daniel Smith

Blister copper from converting of copper matte is processed by fire refining prior to electrorefining. The fire refining consists of two steps: copper oxidation with impurities slagging and copper reduction. The classical batch process is carried out in vascular or reverberatory furnaces called anode furnaces. A new process for continuous copper fire refining has been proposed. The copper flows through two reactors in cascade, where is oxidized and reduced. The flow of a liquid copper through a ceramic packed bed increases the surface area and the rate of oxidation as well as the rate of reduction in the packed bed of charcoal. Mathematical modelling allowed for the design of a laboratory scale demonstration installation and industrial-pilot installation in Hernan Videla Lira Smelter (Paipote). The results have demonstrated the process feasibility and flexibility in operation.

Jan 1, 2009

By M. A. Aziz

The electrochemical performance of a series of carbon materials produced from coconut shells, which are very cheap and readily available in Bangladesh was investigated for their viability as anode materials in rechargeable lithium-ion batteries. X-ray diffraction technique was used to measure the interlayer spacing (d002) of the produced carbon materials. A number of half-cells were prepared with the produced carbon materials from coconut shell as working electrode and metallic lithium as counter electrode with 1MLiPF6 electrolyte in a mixture of ethylene carbonate and dimethyl carbonate. The discharge-charge profiles were measured for the different half-cells by using Arbin 24-channel Cyler. The value of interlayer spacing of the coconut-based carbon material was found to be 0.397 nm at 900°C, which is most suitable for lithium-ion insertion into the carbon structure without any expansion. The specific discharge capacity of carbon material from coconut shell heat treated to 900°C was found to be 1015.65 mAh/g. The coconut carbon material heat treated to 900°C delivered 335.22 mAh/g reversible capacity, which is comparable to the commercial carbon/graphite presently used in lithium-ion battery systems. The irreversible capacity loss and coulombic efficiency in 25th cycle of half-cell made with coconut carbon material were found to be 0.16% and 99.83% respectively. The carbon material produced from coconut shell can, therefore, be used as a potential anode for rechargeable lithium-ion batteries.

Jan 1, 2006

By Waraporn Piyawit

Grinding sludge from the sintered neodymium-iron-boron (NdFeB) magnets production process was enriched with critical rare earth elements (neodymium, dysprosium and praseodymium), which can be up to 30% in the magnets. The demand of NdFeB magnets are simultaneously growing. Therefore, rare earths recovered from waste residue would reduce the demand of rare earth elements from primary sources. In this study, the feasibility of recycling rare earths through a hydrometallurgical process was investigated. The selective leaching of Nd from grinding sludge can successfully raise the rare earths concentration to 70%. The necessity of an oxidation pretreatment to improve the selectivity between Nd and Fe will be described.

By Liangying Wen, Feng Xia, Chenguang Bai

"The situation of the Ti-V-Magnetite samples reduced with microwave has been investigated in laboratory. Firstly, the paper focuses on the heating behaviors of vanadium-titanium magnetite and characteristics of carbothermic reduction of V-Ti-magnetite in the microwave field. The effect of concentrate's size, quality on heating behaviors and reduction processes were researched. Results show that microwave heating may be a new heating resource replace of carbonic combustion reaction in reducing reaction. When the allocation of carbon is (16.7-30)%, carbothermic reduction of V-Ti-magnetite in the microwave field can proceed; with the increasing of carbon mixed, the metallization rate increases; and Fe, V can be reduced from their oxides in the microwave field; Titanic low oxide can be reduced from TiO2.1. IntroductionThe resource of Ti-V-Magnetite is abundant in the western area of Panzhihua in China, so far a mineral deposit of 4.64 billion tons have been proved up, it contains 14.75 million tons of V2O S which accounted for 87% of the vanadium and 5.93 hundred million tons of TiO2 accounted for 94% of the titanium resource respectively in China. The previous study proved that the major composition of mineral of the Ti-V-magnetite are Ti-magnetite, limonite, iron spinel, magnesium spinel etc, and the main elements of the Ti-V-magnetite in this area are Fe, Ti, V, Cr, Co, Ni, Ga, Sc etc[1] Due to the restrict of the BF-BOF process technical, during the smelting of the iron, the level of extracting the vanadium, titanium as well as other metal elements is limited. This results serious wasting of resources. To develop a new reduction process of Ti-V-magnetite is on the agenda, the microwave assistant reduction could meets this need, based on its characteristic of easy controlling of heating rate. To make use of the microwave energy to substitute the released heat sources of carbon combustion with air, use the solid phase state reduction at a relative lower temperature, make the beneficial element in Ti-V-magnetite transferred into the metal phase, then separated from the impurity. It is well worth to point out that once the microwave based reduction method has its industrial scale, it will take an outstanding position by its less release of carbon dioxide. This new environment-friendly process will play a vital role in the development of social industry and economy."

Jan 1, 2008

By Batric Pesic

Gold dissolution with bromine was studied by using the rotating disc technique. Geobram TM 3400 was used as a source of bromine. The parameters studied were: rotating speed, Geobrom 3400 concentration, pH, temperature, sulfuric and hydrochloric acid concentration, and the concentration of various cations (copper, iron, zinc, aluminum, manganese, potassium and sodium) and anions (chloride, bromide, sulfate, nitrate, and iodide) According to the Levich plot and activation energy, gold dissolution was controlled by a chemical reaction rate. Copper, iron, and manganese in their highest oxidation states, aluminum, zinc, sodium and potassium did not have any effect on gold dissolution rate. The presence of manganous ion dramatically decreased the gold dissolution rate. Kinetic performance of bromine, in the form of Geobram TM 3400, was compared with performance of cyanide and thiourea.

Jan 1, 1990

By Lanre Oshinowo

The trend in process engineering is to design compact, more efficient processes, there is the paramount requirement to get the job done right the first time going from the drawing board to full-scale commercial operation. To accomplish this goal, there is also the need for tools beyond the traditional engineering toolkit to evaluate designs through virtual prototyping, thereby reducing the risks associated with making design decisions. One of the most important tools that has recently come to the forefront of process design and development is Computational Fluid Dynamics (CFD). CFD has been used at HATCH to address the key process parameters that drive the design of hydrometallurgical unit operations. This paper will detail the role of CFD at HATCH in achieving a superior level of confidence in the process design of autoclave circuits. Specifically, the optimum application of multiphase modeling including hydrodynamic, heat and mass transfer to hydrometallurgy operations, the impact of non-Newtonian slurry rheology on autoclave performance, and the challenges of optimizing the mixing of key reactants into slurries in autoclave reactors, is discussed.

Jan 1, 2003

By Jing Zhan, Chuanfu Zhang, Yonglin Yao

"The Ni/Co arbitrary ratios of fibrous precursor were investigated during coordinated coprecipitation by changing the precipitating medium. The results show that the original molar ratio ofNi2+ to Co2+ in reaction solution can be maintained in the coprecipitate at pH'.'05.0 and the coprecipitate is single phase solid solution using water and water-X precipitating medium. But the original Ni/Co ratios are no longer kept and composition of the coprecipitate is not uniform at pH>5.0 in water precipitation medium. In order to obtain the precursors with the required morphology and accuracy Ni/Co ratios, the optimum conditions of fibrous precursors were chosen as follows: ammonia used as complex agent and pH adjustor, water-X solvent as precipiting medium, oxalate as coprecipitated agent, 8.0-8.4 for pH value, 50-70°C of reaction temperature, 0.5-0.8 mol/L of initial nickel and cobalt salt concentrations and excesses of oxalic acid of 10% - 20%.IntroductionNi-Co alloy as an important transition metal alloy with high mechanical strength, good anti-deformation, corrosion resistance, thermal conductivity, thermal stability, electrical conductivity, electrical contact, and special magnetic properties indicates that it can be used as high-temperature catalyst, special magnetic material, high-temperature electrochemical devices, and so on [1-6]. An ideal composite powder should have an appropriate stoichiometric ratio, good uniformity of chemical composition, appropriate phase, low impurity content and small particle size [7]. Similarly, the composition of nickel-cobalt alloy powder has an important impact on its crystal structure, properties and applications. Guo[8] found that magnetisms of CoxNi1-x such as magnetic anisotropy, curie temperature, and the shifts of the spin steering are very sensitive to the composition of alloy powder."

Jan 1, 2013

By David G. C. Robertson

A new approach is described for the calculation of the kinetics of metal/slag, metal/slag/gas, and metal/matte/slag/gas reactions. The algorithm assumes that equilibrium is achieved at the interface between phases, and uses an equilibrium solver (such as SOLGASMIX) to compute the equilibrium state at the interface at each time step during the reaction. For multiple phase systems a number of unit operations, representing the different phases and interfaces, must be connected together in a reasonalbly complex manner, and the METSIM software package has been utilized for this purpose. The new approach is superior to the SMAK software developed by the author and his co-workers over the past decade, for the reasons discussed in this paper.

Jan 1, 1995

By Brian G. Thomas

Quality problems in continuous casting of steel can be identified as they occur by monitoring mold signals (level sensor, thermocouples in the mold walls, friction etc.) and taking appropriate action (such as slowing casting speed, changing taper, changing a clogged nozzle, or later visual inspection of the surface for possible downgrading. Surface depressions and groups of deep oscillation marks form at meniscus and reduce local heat transfer as they move down the mold at the casting speed. This slows shell growth, increases shell surface temperature, and causes characteristic dips in mold thermocouple signals. More importantly, they are also associated with longitudinal cracks. Characteristic thermocouple signatures have been identified for many defects, including sticker breakouts, transverse depressions and deep oscillation marks, narrow-face bleeds, transverse comer cracks, longitudinal cracks, mold level fluctuation defects, and other problems. With the help of computational models, these mold signals should be used to troubleshoot defects, and to take appropriate corrective action. Keywords: Continuous casting, defect detection, thermocouple signals, on-line control

Jan 1, 2003

By Ken-ichi Miyazawa

A Center of Excellence (COE) titled the Creation of Nature-Guided Materials Processing, called Nature COE, has been established at Nagoya University. In the Nature COE, a new field of material research is being developed through learning the laws of nature, namely, methods of attaining ?appearance of the maximum function under the minimum substance and energy consumption?, which the nature and living organisms have acquired through their evolution in long period. As one of the specific features, an ?Open Cluster Program? was originated for promoting the researches conducted by young researchers and Ph.D. students with those in and out of the university and also for fostering them, together with such educational programs for Ph.D. students as the research incentive, the oversea training and the international lodging seminar programs. The Open Cluster Program has been found to be effective for fostering of young researchers and students, for promoting their researches, for gathering researchers and knowledge from the world and for propagating the research fruits. Through conducting these programs, world-highest intelligent fruits and a gathering of young minds to lead the new field are expected. In this COE, the researches are conducted on (1) materials used for living bodies, (2) mimicking structures which nature or living bodies are forming and (3) materials processing by mimicking processes to form the structures observed in the nature or the living bodies. These researches are conducted by four groups to extend the processes observed in the natural world to a new type of processing that is thoroughly rationalized by plunging a scalpel of engineering, and to establish a new academic field of materials science and engineering.

Jan 1, 2006

By A. E. Wraith

The tuyère flow rates of Peirce-Smith converters and bath smelting reactors are rendered particularly sensitive to accretion formation, bath depth variations and the general aerodynamic design of the blast delivery system by the limited pressure-flow properties of the conventional single stage centrifugal blower. This sensitivity is examined in terms of tuyère practice, vessel management and fixed engineering parameters for Peirce-Smith converters and the Noranda Reactor by use of the flow resistance factor, R*. New understanding of the effect of accretion growth on the flow behaviour of individual tuyères shows that blowing rates and hence throughputs could be optimised by careful attention to operating detail even within present plant constraints. The concept of the resistance vector is introduced to elucidate comparisons between different practices and to provide reference standards for optimisation. On this basis, the benefits of introducing quite moderate changes in the pressure-flow properties of the blast delivery system are considered. In view of recent developments in the flexible use of converters as hybrid bath smelting vessels for matte production, the foundation is now laid for a searching consideration of relationships between vessel volume and shape, blowing requirements, tuyère performance and production rates, the detail of which will be examined more appropriately in a forthcoming paper.

Jan 1, 1999

By Rune Gammelsmter

Turbulent chemically reacting flows are generally very complex, involving interactions of chemical, thermodynamic, and fluid mechanical processes. A combustion model based oh algebraic moment closure has been developed. The model is applicable for reaction rates where the chemical kinetics can vary from slow to fast. The effects of turbulence is taken into account by means of modifications to the well known k-e modelling procedure. The model is applied to an industrial combustion process. Calculation of furnace off-gas combustion from an aluminum reduction cell has been performed. The theoretical results agree well with experimental values.

Jan 1, 1992

By María Cristina Ruiz

Hematite precipitation is a convenient alternative for the removal of iron from leaching circuits because of its chemical stability, high density and high iron content. The precipitation of hematite from ferrous sulfate solutions was studied in a batch reactor. The precipitation occurs by two sequential steps: oxidation of the ferrous to ferric ions followed by hydrolysis of the ferric to hematite. The main objective of this study was to determine the effect of the main operating variables on the rate of two steps of hematite precipitation. The variables studied included: stirring speed (100 to 600 rpm), temperature (160 to 200 ºC), concentration of sulfuric acid (1 to 10 g/L), initial iron concentration (1 to 15 g/L), and partial pressure of oxygen (1 to 6 atm). The sulfur content and the particle size of the solids that precipitated under various conditions were also determined. The results showed that at low temperature and high acid concentration the rate of Fe3+ hydrolysis is the step that controls the overall process. The variable that affects most the rate of Fe2+ to Fe3+ oxidation and the rate of hematite precipitation is the temperature.

Jan 1, 2008

By S. Seetharaman

The present paper presents. the concept of micro-models and illustrates the application of the same in the simulations metallurgical processes. Development of micromodels requires access to accurate thermodynamic, thermophysicaland kinetic information for the relevant systems with suitable models to extrapolate the data as functions of temperature and composition. Experimental measurements and modelling of the thermodynamic properties, sulphide capacities and viscosities of oxide melts carried out in the department are presented. The incorporation of these models in process models, with special reference to ladle refining of steel is illustrated. Typical example of micro-modelling of solid-gas reactions is also presented.

Jan 1, 1999

By Jinliang Zhang, Jian Pan, Deqing Zhu

"Limestone and burnt magnesite were added to vary MgO content and basicity (CaO/SiO2 ratio) of pellets for investigating their influences on the properties of specularite pellets. At fixed MgO content, the addition of limestone does not affect on the properties of green balls significantly. The addition of burnt magnesite has obvious influence on the quality of green balls, especially on the thermal shock temperature. Without burnt magnesite, the thermal shock temperatures are about 400°C, and, the thermal shock temperature increases to 600~630°C by adding burnt magnesite. For preheated pellets, when the burnt magnesite is added, the compressive strength will be decreased. For roasted pellets without burnt magnesite, the calcium additives can form binding phase of calcium-ferrite, and suitable liquid phase will improve recrystallization of hematite, but excessive liquid will destroy the structure of pellets, so the compressive strength of pellet increases firstly and then decreases. When adding burnt magnesite, the compressive strength will increase as the basicity increases. When the basicity is more than 0.2, the compressive strength of the pellets various MgO content and basicity is above 2500N/pellet and then MgO-bearing fluxes can be added to prepare pellets with good high temperature properties.IntroductionWith the rapid development of the steel industry in China, oxidized pellets, possessing good mechanical and metallurgical properties, are becoming indispensable burdens for blast furnace ironmaking [1-3]. However, this has resulted in the shortage of domestic iron concentrates, so many Chinese steel plants begin to use imported hematite concentrate to prepare pellets. Compared with magnetite pellets, the hematite pellets require high roasting temperature and narrow roasting temperature range (1300–1350°C) and possess low compressive strength [4,5].1"

Jan 1, 2012

By S. Viswanathan, Q. Han, A. S. Sabau

"In spite of recent advances in the mathematical modeling of fluid dynamics for materials processing applications, no significant advances have been made in the numerical discretization of these equations. In this work, the application of two-step projection methods for the numerical simulation of interdendritic flows is discussed. Unlike previous methods, the methods presented here are constructed for the exact equations which are characterized by variable density and volumetric fraction of the liquid. The drag terms, which describe the momentum loss due to the flow around and through the dendrite structures, are treated implicitly. Numerical examples for shrinkage-induced flow during solidification of an Al-4.5% Cu alloy bar is used to illustrate the effectiveness of the proposed algorithm.IntroductionLiquid contraction during solidification plays an important role in the formation of casting defects such as shrinkage voids, microporosity, and macrosegregation. Owing to their importance, the study of transport processes during solidification have received considerable attention during the past years [1, 2]. By the use of volume-averaging techniques, the mass and momentum equations for flow through a stationary dendritic structure were derived [3]. By using the volume-averaging techniques for multi-phase systems, two-phase transport equations for solidification problems were derived [4]."

Jan 1, 1999

By W. G. Davenport

All Outokumpu flash furnaces burn some hydrocarbon fuel. Hydrocarbon combustion supplements heat from Fe and S oxidation and provides local heating in cool; parts of the furnace. Adjustment of hydrocarbon fuel combustion rate is an effective way of controlling furnace temperature. More oxygen and more oxidation of Fe?and S in the flash furnace continue to diminish the need for1hydrocarbon fuel. Still, as Tables 2.1 and 3.1 show, all flash furnaces use it. Oil is the most common fuel -natural gas, coal and coke are also used. This chapter demonstrates how hydrocarbon fuel is included in our flash furnace matrix. It shows that: (a) three new variables, mass hydrocarbonfoel. mass CO2 in offgas and mass H2O in offgas are inserted (b) carbon and hydrogen balances are added (c) hydrocarbon fuel quantity is specified (d) ,the oxygen balance is modified to include CO2 and H2O (e) the enthalpy balance is modified to include hydrocarbon fuel, CO2 and H20.

Jan 1, 2001

By E. Ilgar

"Deposition studies were conducted in acid copper electrolyte to determine the influence of chloride ions on cathode morphology. A statistically designed screening test was carried out in the absence and presence of 20 ppm CI- using a three factor, two level factorial design, in an electrolyte containing 36 gl'! Cu2+ and 150 gl-! H2S04, The independent variables evaluated were agitation; current density and temperature and their influence on surface roughness was determined. The copper deposited at current densities where activation was the primary control mechanism appeared similar in morphology whether stirring was used or not. The addition of 20 ppm CI- to the electrolyte gave rougher deposits under the same conditions. In the mixed control regions, considerably rougher, dendritic deposits were obtained when CI- was present. Agitation was effective in reducing the copper surface roughness both in the apparent activation and mixed control regions in the presence ofCI-. The results of this study showed that 20 ppm Cl- polarized the copper deposition at low overpotentials but caused depolarization at higher overpotentials.IntroductionChloride ion is inherently present in copper electrolyte, either as an additive or from other sources such as make up water. The behavior of the chloride ion is well documented in electrorefining operations, but its role in copper winning is less obvious. However in both cases there is evidence that cathode growth and solution chemistry are strongly influenced by its presence. The mechanism and electrochemical action of the Cl"" have been shown to be very complex, therefore a better understanding of its influence on electrocrystallization is essential for improved cathode deposit growth control. It was proposed that Cl"" polarizes the copper deposition reaction at low concentrations due to CuCI formation but depolarization occurs at higher concentrations due to the formation of a soluble CuCI2"" complex [1,2]. Franklin [3] reviewed the mechanism of additives in the electrodeposition process and proposed that the Cl"" complexed with copper, adsorbed on the cathode as an induced anion leading to an increase in the reduction rate. At cathodic overpotentials less than 100 mY, lppm NaCl had a polarizing effect, i.e. an increase in impedance of the charge transfer step. At higher Cl"" concentrations up to 100 ppm, depolarization occurred as evidenced by a decrease in impedance, which was attributed to soluble cuprous complexes [4]."

Jan 1, 1997