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By Veena Sahajwalla

The cupola furnace is a coke-fueled shaft furnace used as a primary melting unit in iron foundries. Control of chemical composition of the iron tapped from the cupola is a key factor in productivity and quality control. In an effort to develop a control model for the cupola, a fundamental approach based on physical and chemical principles has been taken to describe the melting process. The behavior of oxidation of the solid charge in the stack of the cupola has been studied. Sulfidation of the charge materials by sulfur-bearing components released to the furnace gases from the coke has been described. Carburization of metal droplets of iron and of steel in separate molten streams has been characterized. Finally, reactions with alloying elements in the hearth (well) of the furnace have been defined. These reactions have been described in a computer-implemented model developed to predict the composition of the iron tapped from the cupola. The model has utilized the thermodynamics and kinetics of the oxidation, sulfidation, and carburization reactions, including temperature and physical aspects, in the various zones of the melting unit. The model predictions have been compared favorably with operating results.

Jan 1, 1992

By Andreas Orth

Outokumpu Lurgi Metallurgie has developed a process for the calcination and reduction of laterite nickel ore tines where the reduction of iron and nickel to the wustite/metallic states respectively, is performed in a fluidized bed reactor using reduction gas generated very cost effectively from natural gas in an autothermal catalytic reactor. As an option coal can be used as reductant as well as additional fuel. The process of reduction and calcination is very energy optimized. It uses the off gas from the fluidized bed reduction reactor, which still contains energy, to dry and calcine the nickel ore fines in a primary stage circulating fluidized bed (CFB) reactor. The product shows high metallisation of nickel and iron oxides reduced to the wustite stage. This results in considerable energy savings in smelting the prereduced product to ferro-nickel. Alternatively the product can be leached to produce nickel. Laboratory tests showed very high recovery of nickel and cobalt. Keywords: Fluidized Bed, Prereduction, Calcination, Ferro-Nickel

Jan 1, 2004

By W. G. Davenport

Chapters 19 and 20 examine direcHo-copper flash smelting and flash converting. This chapter compares the two processes and suggests which is likely to be 'the more economic for a given concentrate. It: (a) uses Chapter 19's direct-to-copper industrial oxygen and oil requirements (b) adds the energy required for electric furnace recovery of Cu from direct-to-copper slag (Czemecki et al 1999) (c) combines Chapter 20's, flash converting calculations with Chapter 18's flash smelting calculations to determine their combined industrial oxygen and hydrocarbon fuel requirements (d) adds the energy required to granulate, crush and dry flash smelting matte for the flash converter (e) adds the energy required to granulate and dry flash converter slag for recycle to flash smelting (f) compares direct-to-copper and flash smelting/flash converting in terms of their total equivalent hydrocarbon ener.gy requirements.

Jan 1, 2001

By N. Kanari

Chalcopyrite concentrates and their pure constituents were chlorinated by C12+N2 between 25 °C and 750 °C. The reaction products were analyzed by SEM, XRD and chemical analysis. The effect of gas flow rate and chlorine content of the gas mixture on the reaction rate were investigated. At room temperature, these solids start to react with chlorine giving metal and sulfur chlorides. Complete reaction is achieved at about 300 °C and the iron and sulfur chlorides were fully volatilized. The chlorination residue is composed of valuable metals' chlorides. A simplified flow - sheet for the treatment of chalcopyrite concentrates by chlorine was suggested.

Jan 1, 1998

By B. J. Vorster

AngloGold South Africa region currently consists of 12 Gold Plants. These plants use a combined total of $20 million of cyanide per annum. Of this, the .major portion (60%) is consumed at two Ergo dump retreatment plants. Historically the primary motivation for cyanide control at Ergo has been one of leachlcost optimisation. However, more recently, with the increased public awareness of cyanide in the environment, a secondary but increasingly important motivation for control has been to ensure that only the minimum amount of cyanide is added to the process whilst not compromising leach performance. Following a brief overview of the Ergo process, the methodology in detennining the amount of cyanide to be added is described. The paper then traces the developments in cyanide control from very basic? manual systems to the current automated control system. In line with the increasingly sophisticated control systems, developments also took place in regards to the method of cyanide analysis. The development of these analysers is also discussed. Whilst cyanide is one of the major drivers, if not the major driver of gold dissolution, it cannot be viewed in. isolation particularly with respect to the relationship between cyanide and oxygen as ascertained from the Elsner's well known equation. Consequently, in order to control cyanide addition, knowledge of the relative cyanide/oxygen profiles is necessary. Various means investigated at Ergo for pulp oxygenation have therefore been included for the sake of completeness. Finally a comparison is made of the control achieved from the current system compared to the? original manual system. The knowledge and experience gained at Ergo is now being used to draw up guidelines for the installation and optimisation work at the other AngloGold plants. The net effect of this will be reduced cyanide consumption for the region, which also, apart from the obvious economic benefit, translates into a reduced environmental; risk.

Jan 1, 1998

By Jong-Ren Tarng, Gin-Hwa Chen, Wen-ku Chang, Ke-Ming Lin, Yuan-Haun Lee

"The majority of early studies used X-ray diffraction, but this requires a model to interpret the diffraction processes. A turbostratic model has been applied by Warren, Franklin and Bacon to a wide range of materials including both soft and hard carbons. Maire and Mering applied the same methods to the interpretation of the (001) lines of a series of graphitic carbons. In our case, graphitic carbons undergone high temperature and high pressure graphitization processes have been evaluated by the same methods. It were found that most technological XRD data were obtained by a Rietveld method with the least-squares refinements could be in the simplest way since the full correction technique is very laborious. The behavior of carbon materials as it proceeds through the graphitization process is characterized by changes in the measured interlayer spacings (d) a~ a function of temperature. A series of graphitic carbons including the transformation of diamond to graphite through the process under high temperature and high pressure have been evaluated. A simple calibration equation has been established. IntroductionRecently, in battery industry, carbon materials are used as cathode in lithium ion batteries. However, graphitization of those carbon materials is concerned as if lithium ion intercalated into those carbon cathode. Both high-graphitization and low-graphitization carbon materials are suitable for this kind of application.As for graphitization, the starling materials from which carbons may be prepared vary extensively from pure chemical compounds, to mixtures containing II wide range of molecular weights, such as pitches. So its graphitizing, perhaps the most notable feature of the process, is the very wide range of temperature over which the perfection increase, unlike the more common transformations of solid state materials which occur in a narrow temperature range. The variables involved in the conversion of the initial hydrocarbon to a carbon residue, which may vary widely in final perfection, are time, temperature, stress and impurity content"

Jan 1, 1996

By F. Michael Hosking

Modeling of a furnace brazing process is described. The computational tools predict the thermal response of loaded hardware in a hydrogen brazing furnace to programmed furnace profiles. Experiments were conducted to validate the model and resolve computational uncertainties. The results from selected furnace simulations and measured thermal events were compared. Critical boundary conditions that affect materials and processing response to the furnace environment were determined. "Global" and local issues (i.e., at the furnace/hardware and joint levels, respectively) are discussed. The ability to accurately simulate and control furnace conditions is examined.

Jan 1, 1998

By Ting Lei, Mingjun Rao, Guanghui Li, Tao Jiang

"With the rapid development of iron and steel industry, the supply of iron ores can not meet the present demand for iron and steel industry in China. Large reserves of oolitic hematite have been discovered with low iron grade (30% ~ 45%) and high phosphorus content (0.4% ~ 1.8%). Traditional processes for utilization of this ore are characterized as either high cost or low dephosphorization. In this study, sodium salts-modified paigeite (SSMP) was added to enhance on the dephosphorization of high-phosphorus oolitic hematite by using reduction roasting followed by magnetic separation. Various parameters, including the amount of SSMP, reduction time,reduction temperature, grinding fineness and the magnetic field intensity were investigated. As a consequence, a magnetic concentrate of metallic iron powder with total iron grade of 93.2% and phosphorus content of 0.08% was obtained under the optimal conditions. The results also provide a potential avenue for the comprehensive utilization of paigeite ore.IntroductionOolitic hematite is currently recognized as one of the most refractory iron ore resources in the world. Over 4.0 billion tons of reserves of such resources have been found in China, and more than 10 billion tons in the long-term. This kind of ore is characterized as low iron grade (30%~45% TFe) and high phosphorus content (0.4%~1.8% P), as well as fine particle size distribution of ferrous minerals (the size distribution varies from 5~30 µm, even less than 2 µm) and the complex association between iron and other gangue elements [1~5]. The unique structural characteristics of the high phosphorus oolitic hematite make it difficult to obtain high iron recovery and good dephosphorization efficiency by using the conventional processes [1,2]. Traditional processes are characterized as high cost and low dephosphorization for oolitic hematite beneficiation [9~15]."

Jan 1, 2012

By F. K. Letowski

Leaching in froth is a particular case of a three phase (liquid-solid-gaseous) process which combines flotation with leaching by using a reactive gaseous reagent as a flotation carrier and a leaching solution as the reactive liquid medium to fonn the foam (froth) in' which the solid particles are suspended. Some physico-chemical and engineering aspects of leaching in froth are discussed and illustrated by its application for cleaning the mineral graphite. Leaching of the graphite concentrate containing 4L4% of the elemental carbon and 3.16% of the sulphidic 'sulphur was canied out in the froth fonned by: (a) a concentrated chloride solution, with a small addition of nitric acid, in the foam state; (b) a mixture of gaseous O2, NO., and H20 encapsulated in the foam; and (c) notable particles of graphite suspended in the foam. The laboratory experiments werecanied out in a "flotation column"-type reactor ala temperature from 80 to !08°C and under total pressure of 100 to 200kPa. In the 3-stage leaching-flotation process, the non-flotable fraction of particles was separated three times from the notable fraction. The concentration of carbon and elemental sulphur in the final flotable fraction was 96% C and 0.38% S respectively. The expected advantages and possible application in hydrometallurgy are suggested.

Jan 1, 1995

By Liwen Hu, Jianxun Song, Hongmin Zhu, Qiuyu Wang, Shuqiang Jiao

The subchloride titanium was prepared by sponge titanium and titanium tetrachloride in the CaCl2 at 1173 K. The species were detected are mainly titanium dichloride, and the average valent in the melt are 2.05. The accurate equilibrium constants were obtained for the reaction 3Ti2+ = 2Ti3++Ti after the accurate activities of titanium chloride were evaluated with emf method, and the observed deviations from ideal behavior are discussed.

Jan 1, 2015

By George Kazonich

The high costs and environmental problems associated with making iron and steel in the United States is driving the development of new technologies to replace the blast furnace. A prototype reactor incorporating rocket technology was designed and built. This rapid rate reactor was operated successfully and consistently made iron metal. Minus 325-mesh magnetite particles could be reduced to iron metal in less than 50 ms in a high temperature flow through reactor. Iron product was recovered inside the reactor and in a downstream cyclonic separator. The results of typical operation and how parametric changes affected the reduction of iron ore concentrates are discussed.

Jan 1, 1993

By E. Charles Abbey

Manganese in electrolyte has both beneficial and detrimental effects in Zn electrowinning. Mn oxidizes to form MnO2 on Pb–Ag anodes, cell walls and pipes. MnO2 reduces anode corrosion but also leads to short circuiting and maintenance issues. MnO2 is thought to interact with chloride ions and produce oxidized chlorine species. The interactions between Mn and Cl are not well understood. Therefore, two sets of 45+ day bench scale experiments were conducted to investigate the effects of the manganese to chloride ratio on anode corrosion rate and electrolyte chemistry using rolled Pb–Ag anodes. Daily manganese and chloride losses from the electrolyte appeared to be correlated. Increasing the average Mn/Cl− ratio from ∼7:1 to ∼11:1 reduced the anode corrosion rate. Increasing the ratio above 11 did not reduce the corrosion rate further. Anode scales produced with Mn/Cl− ratios at and above 11:1 contained some γ–MnO2 while scales formed with ratios less than 11:1 did not.

By Seshadri Seetharuman

The present paper summarises a series of measurements of the interaction parameter of oxygen in liquid copper with respect to a third element, e(M)o, where M is Mn, Zn, As, Se or Te which are common impurities in the liquid metal. The technique employed was the solid electrolyte galvanic cell method. The cell used may be represented as Pt, W or cermet / Cu-O-M // ZrO2 - CaO // AO, A /PT where AO/A represents a suitable oxide/metal reference. The measurements indicate that Mn and Zn interact very strongly with oxygen in liquid copper while, in the case of arsenic the interaction parameter is nearly zero. The behaviour of the elements Se and Te is unique with respect to oxygen interactions in copper bath. At oxygen levels, xo= 10-4 ? 10-5, the apparent interaction parameters are negative, comparable to that for sulphur. On the other hand, at lower oxygen levels, the results indicate that the interaction parameter values are positive. The results are discussed in the light of some of the theoretical models for solute interactions in liquid metals.

Jan 1, 1993

By V. M. Sokolov, Jr. DuPlessis

The technology for recycling fine wastes, grinding sludges or swarf, and solids such as slag that contain a high content of metallic material needed improving. The objective was to produce a master alloy that met the tight requirements of the Western manufacturers and achieve improved yields of the valuable elements, nickel and cobalt, to over 90%. The alloys from the production of Alnico. magnets were chosen for this work. A process is proposed .that is able to recycle all kinds of Alnico wastes. This process is able to reduce all detrimental elements, which are contained in the wastes, to within acceptable levels. Molybdenum, if present, is an exception. Depending on the levels of contamination of undesirable elements different recycling strategies are proposed. The majority of the wastes can be recycled by melting and refining with a liquid slag layer using unique melting furnaces that are relatively unknown in Western nations. The proposed technologies allow the reelamation of over 95% of the cobalt and nickel from any kind of Alnico waste, and there are no limitations on the proportion of different kinds of wastes in the charge. The proposed processes and technologies could also be applied to the recycling of grindings, turnin

Jan 1, 2000

By G. Glinski, K. A. Pericleous

"Recent advances in new computational modelling techniques such as Lattice-Boltzmann and Dissipative Particle methods offer the prospect of simulating complex fluids such as colloidal and dense suspensions in industrial processes. They are referred to as mesoscopic methods since they lie between molecular dynamics at a microscopic atomistic scale «lO-9m) and traditional macroscopic CFD methods (> 1O-2m). The models behave like a 'coarse-grained' gas consisting of fictitious interacting particles, which are much larger than the real molecules of the actual fluid they represent. Inter-particle forces are set so that the collisions collectively mimic the phenomenological transport properties and flow of the underlying fluid at a macroscopic scale.Much of the developmental work to date has focused on laying theoretical foundations based on thermodynamic and kinetic theory. Successful applications include predictions of macroscopic transport properties of complex fluids and flows in porous media and filters. With the constant increase in computational power, these mesoscopic methods are now sufficiently developed to determine their suitability to simulate complex fluid flows in real industrial processes. This work describes the application of meso scopic methods to the stencil printing of solder pastes in the assembly of electronic components. The aim of this work is to assess the ability of these methods to study the transport mechanisms of individual solder particles suspended in the flux solvent as they enter and fill the micro-apertures of a stencil. This paper demonstrates the coupling of such mesoscopic methods to continuum CFD methods to predict the flow of dense suspensions (i.e. solder paste) in industrial processes."

Jan 1, 2001

By A. P. Paiva

Although the advantages of Solvent Extraction for separation/purification of relatively concentrated solutions are well known in Extractive Metallurgy, its use for the recovery of elements present in low levels only recently has been discussed, with particular attention devoted to precious metals. In this work, the extraction behaviour of Cyanex 471X towards silver, from an acidic chloride medium is reported, the extraction and stripping isotherms and related kinetic features analysed. Results on the selectivity of silver extraction against high contents of iron, copper and lead are discussed. Phosphine sulphide extractants are generally associated with solvation mechanisms: analysis of the extraction pathways along with the possibility of reaching a suitable loading in the organic phase are also presented.

Jan 1, 1993

By Bing Ji Yan, Cui Wang, Ya Peng Zhang, Chuan Hui Li, Hong Wei Guo, Jian Liang Zhang

There are a lot of research of the chlorine element’s influence on blast furnace, and mainly pay close attention to the harm to gas pipes and equipment. There are three kinds of chloride in the blast furnace gas, including HCl, NH4Cl, and NaCl (or KCl, ZnCl, etc.). This paper mainly analyzes all kinds of phenomenon of the chlorine element overflowing blast furnaces in Jinan Steel, and puts forward some different viewpoints, which are that the chloride overflowing out of blast furnace in the types of HCl, NH4Cl, or NaCl (KCl) not only has much to do with raw materials of chlorine load level, at the same time with the blast furnace burden distribution. On this basis, comes up with countermeasures for the different situation, such as adjusting the burden distribution matrix to guarantee the central gas flow smooth and changing the kind of raw materials to reduce the chlorine quantity, which will be helpful to prevent the harmful influence of chlorine element.

Mar 1, 2017

By J. E. Klein

Bench scale tests using a stack of ten whole SAES St909 pellets, 6 grams, to crack methane have been completed with pure methane feed. Test conditions ranged from 600 to 800°C at 101 kPa (760 ton) with a methane feed rate of ten sccm. Methane reformation tests, test where hydrogen was passed through a St909 bed after cracking methane, were performed to determine if and how much methane can be generated under "reformation" conditions. Phase structure determinations of St909, composed of a ZrMnFe alloy with aluminum used as a pellet binder, after methane cracking were complicated by the number of materials that can be formed by the elements in the St909 and the carbon from methane cracking. It was determined that the aluminum not only alloys with the Zr, Mn, and Fe in the St909 alloy, but also forms aluminum transition metal carbides in addition to ZrC as the carbon content and the temperature of the St909 increases. Some A14C3 was also found in some pellets. Passing hydrogen over St909 pellets after methane cracking formed methane at various rates in the temperature range of 600 to 800°C. Temperatures of 800°C gave the best methane cracking performance and efficiencies decreased rapidly with temperature.

Jan 1, 2002

By A. Haxhiaj, E. Haxhiaj

"The paper has as a studying object the issue of effective management of gasses’ heating and dusts in reductive melting process in lead (Pb) metallurgy. It also analyses the issue related to the usage and recycling of dusts and gasses in all pyro-metallurgical processes of technical lead production. The paper contains the analysis of technological process of separation of humidity, gasses, and dusts of valuable remainders in “Trepça” plant. Paper has the results of theoreticalexperimental studying, analytical and graphical of gasses thermal balance depending on height and composition of load, and the coke quantity on load for reductive melt in “Water-Jacket” furnaces. With thermal balance, having into consideration all parameters of heat in entry and exit depending on aforementioned factors we aimed to optimize the parameters of the process, keeping the attention to the minimization of energy consumption, and the overall influence on environment.1. IntroductionThe upper part of the furnace which is the study point of this paper lies from the reactions zone of Water-Jacket furnace and it also includes the furnace neck. In this zone has been elaborated the zonal material balance referenced third in the row. The separation of humidity, dusts, gases and lead with gases depends on many parameters like temperature, load composition, and height of load inserted in the furnace, and also the height of preheating zone in Water-jacket furnace. Lead oxidizes in reaction zone of the furnace and exhales with gases like dusts and small particles after which falls in worthy storage of Trepça plant and has negative effects in environment, and economic stability of reductive melting process of Water-jacket furnace. Thermal balance of gases in this zone depends on many factors; height and load composition, coke quantity in a load. The calculation has been done as the standard methodology of thermal calculation is done; moreover, by using a computer for mathematical models which enables very accurate results. We must emphasize that acquired and used heat in reaction zone and melted materials is calculated in others studies, so their influence in preheating zone is assumed."

Jan 1, 2010

By Giacobbe Braccio, Alessandro Blasi, Assunta Romanelli, Massimo Morgana, Corradino Sposato

Yttrium is a strategical material for its several usages in a wide range of industrial production. For this reason, improving the recovery of Yttrium has become a crucial focus for international research. In this scientific activity, the utilization of two extractants, 2-ethylhexyl-mono 2-ethylhexyl ester phosphonic acid (P-507) and sec-octylphenoxy acetic acid (CA-12), working in a synergistic extracting system, has been tested. A series of trials have been carried out to optimize the experimental conditions in order to separate yttrium from a mix of heavy rare earths in chloride media. Tests with different relative concentrations of extractants and a phase modifier (TPB, trybutyl phosphate), with different presaponification rate, have been performed to evaluate the behavior of the synergistic system. Results are very promising to recover and separate yttrium with a high purity.

Mar 1, 2017