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By V. A. Bryukvin

A characteristic feature of the macrokinetics of the interaction process is the presence of two specifically defined areas of oxidation which had a linear time dependence. The effect of variables, such as residual sulphur content of the melt, temperature and the oxidation potential of the gas phase, on the macrokinetics of oxidation are investigated. Phase composition and structure of products of solidification of partially oxidised melts and thermodynamic properties pentaining to Cu-S-O melts are used to analyze the macrokinetic behaviour and mechanisms of the interaction. The process of interaction of sulfide copper melts with oxygen may be considered as a disproportional absorption process and its mechanism is based on localized interaction on the surface and inside the melt volume. Superficial processes include also the process of primary chemisorption of oxygen by melts at place of metal-metal donor bonds proceeding with formation of oxysulfide liquid solutions and volumetric decomposition of the latter accompanied by evolution of sulfur dioxide and metallization of sulfide melts. It is the degree of dynamic balance of such interaction processes that determines specific individual features of the macro-kinetics and mechanism of oxidation of sulfide copper solutions with oxygen in the gas phase.

Jan 1, 2006

By Harvey Alter

National attention in, recycling focuses on municipal solid waste (MSW), even though only about 50'million tons or so of MSW can be recycled, including grass, leaves and other yard wastes. The scope and value of the recycling of industrial "wastes" is much greater. It is possible to account for some 240 million tons of material recycled at the industrial scale annually, which is likely a conservative estimate. Some of this recycling reduces what would otherwise be hazardous waste to 'comrnodities and non-hazardous residue. Global trade in recycled commodities is outlined, as well as the-effect of the Basel Convention on the Trans boundary Movement of Hazardous Wastes A recent Decision under the Convention can, diminish the trade; deny developing countries needed secondary raw materials, and put world markets in chaos. Current U.S. government policies and activities toward ratification of the Convention, and possible new regulation of industrial recycling activities, will be discussed. There are federal proposals that would regulate industrial recycling differently for on-site and off-site facilities and judge legitimate or "sham" recycling according to the concentration of so-called "toxics along for the ride."

Jan 1, 1995

By Armando Valenzuela

Arsenic has been a common impurity in copper sulfide concentrates treated pyrometallurgically in Chile, which inevitably during the smelting-converting process reports in the final copper product affecting its properties, but also affecting environment as a very toxic occupational hazard. The enforcement of air quality standards, which regulate pollutants such as sulfur dioxide, particulate matter, and arsenic, has resulted in the implementation of pollution abatement plans and emission reduction schedules mainly by state-owned copper concentrate smelters. Investments associated with these plans incorporated gas-handling systems in order to capture polluting emissions. Electrostatic precipitators recover dusts containing mainly Cu and As which are leached to recover copper, while arsenic is disposed currently in the form of ferric arsenate. Gases containing high sulfur dioxide content are treated in plants to produce sulfuric acid, which is used in various classical and new hydrometallurgical processes. Additionally, smelters have effluents treatment plants for arsenic disposal either as ferric arsenate or calcium arsenate/arsenite. This paper reviews the environmental situation of the Chilean metallurgical industry, and the present trends for arsenic management are particularly emphasized since Chile is the world?s largest copper producer.

Jan 1, 2006

By George J. Karcas

"Non-ferrous metals such as copper, nickel, lead, zinc and precious metals are produced via the electrorefining and electrowinning processes. Apart from controlling electro-chemical conditions for the production of these metals, there has always existed the challenge of controlling the corrosive effect of the electrolyte environment which serves as the medium for non-ferrous metal production.The practice of acid containment in electrometallurgical operations has entered the world of high technology with the advent of advanced acid resistant materials such as vinyl ester resin which is either combined with aggregate to form polymer concrete or used to line various acid containment vessels and ·surfaces. ill comparison to some Asian, European, and African copper refineries, the North and South American copper industry has recently embraced quite heavily in the use of polymer concrete electrolytic cells and process vessels, such as electrolyte storage tanks, and in the use of vinyl ester resin for corrosion protective surface sealing 'systems in lieu of epoxy, acrylic and other materials because of its combination of higher corrosion resistance and superior flexibility.Electrolytic cell construction has undergone a transformation from a multiple part configuration to a single piece moulded/cast unit. ·The one piece moulded polymer concrete cell, which has been patented by Corrosion Technology International, with the overflow, decant, inlet, fast fill and segregation systems integrally designed is now the industry standard.. The combination of a wood, steel, or concrete frame with a lining made of lead, asphalt, rubber or plastic has been historically successful in providing limited protection from chemical and mechanical attack in electrolytic cells and electrolyte storage tanks all over the world. These combinations have now become obsolete as materials such as polymer concrete provide exceptional corrosion and mechanical protection with greatly reduced maintenance requirements and improved efficiency and productivity for the tankhouse. ill addition, polymer concrete can be disposed of in a regular land fIll which is much less costly than disposing of contaminated concrete that is normally associated with conventional lined concrete cells."

Jan 1, 1997

By Yin Zhang, Xiaoyu Huang, Mi Wang, Bencheng Du, Youduo He

"Burners are important facilities for blast furnace stoves to raise hot-blast temperature up to 1200°C. Common types of two-ring ceramic burners have very long flames so that part of combustion occurs in the upper part of the chequers and will cause damage to the refractory materials. Using computer simulation to analyze the turbulent diffusion flame in the combustion chamber, some good results were obtained. A new type of ceramic burner will be installed by Anshan Steel Complex in stoves of blast furnace number 4. A pilot experiment was done on the new burner. The experimental data have shown that the mixing condition was improved and the length of flame was shorter with the new type of ceramic burner.IntroductionPulverized-coal injection can give significant operating saving, reducing coke rate in blast furnace(BF) operation. However, during high rates of coal injection, extra heat must be compensated in hearth to maintain certain raceway adiabatic flame temperature. One of the effective methods for heat compensation is to raise hot-blast (HB) temperature up to 1200°C. Nowadays, since the fuel being combusted in stoves is BF gas only, in which the calorific value is down to round 3000 kJ/m3 , to increase the combustion ability and to provide a suitable length of flame in combustion chambers of stoves becomes more important. In other words, designing a good ceramic burner which will affect to HB temperature and stove lifetime is drawing more attention."

Jan 1, 1999

By Daoxin Wu, Zhong Cao, Yan Shi, Yu Ding, Huanli Yang, Zhongliang Xiao

"2-substituted benzimidazole-zinc and 2-substituted benzimidazole-copper complexes were main components of organic solderability preservative (OSP) in PCB producing process and affect the thermal stability of OSP film. So these four complexes were prepared by 2-substitutedbenzimidazole reacting with zinc ion and copper ion, the complexes crystals were determined by IR, its thermal stabilities were studied by TG method. The results indicated that the thermal stability of 2-substituted benzimidazole-zinc is higher than the 2-substituted benzimidazole copper,and the thermal decomposition mechanism was presentedIntroductionImidazole compounds which is an important heterocyclic compound shows the important value and outstanding prospects[I-3l in field of biological engineering, medicine, and high-performance composites. It's said that imidazole compounds is an excellent new metal surface treatment[4] agent, because it has good reaction activity with metals and can form a chemical layer on the metal surface. The complexes of imidazole were main components of organic solderability preservative (OSP) in PCB producing process and affect the thermal stability of OSP film. The mechanism of imodazole combined with metal and film deposited has been reported, but the opinions about thermal stability of film have bifurcation, let alone the thermal decomposition mechanism of film at high temperature. The complexes were prepared by combining of 2- substituted-benzimidazole with zinc and copper iron, which were studied by IR and TG method, in order to get thermal stability of different complexes."

Jan 1, 2011

By Li Zhang

A novel green technology to recovery Titanium compounds from Ti-bearing blast furnace slag under the dynamic oxidation condition was developed and tested. Air was blown into the molten slag as oxygen resource through a lance during the dynamic oxidation process, in which six important results were found: (1) The TiC, (Ti2O3), Fe and (FeO) in the slag were oxidized; (2) The temperature of slag temperature rapidly increased; (3) The viscosity of slag decreased; (4) The coalescence, growth and drop of the metallic Fe droplets in the molten slag were carried out under an air agitation condition; (5) The dispersed Ti components were selectively enriched into the perovslite phase, and the perovskite phase could be selectively precipitate and grow. And also, the perovskite phase can be separated by the dressing method. The oxidation of molten slag gives off a large amount of heat, which helps chemical reactions proceed, improve the rate of chemical reactions, and promote the precipitation and growth of the perovskite phase. The features of the technique are clean, low cost and a great capacity to deal with a large quantity of slag. It was confirmed by experiments that the precipitation of the perovskite (CaTiO3) in molten slag is obviously affected by operation factors such as temperature, chemical composition, heat-treatment, additives and so on. The precipitating kinetics and mechanism of the perovskite phase from molten slag during the dynamic oxidation processes were also investigated.

Jan 1, 2006

By Hande Cavus, Ibrahim Yusufoglu, Cem Kahruman

"In this study, ammonium tetramolybdate (ATM) was obtained as the intermediate product of ammonium heptamolybdate tetrahydrate (AHM). The thermal decomposition mechanism of ATM was investigated under nonisothermal and isothermal conditions in air and inert gas atmospheres. Nonisothermal experiments were carried out by TGA/DTA/MS while TG was used for isothermal conditions. Characterization of the decomposition products were carried out by XRD and FT-IR. The thermal decomposition of ATM in air proceeds in a single step and forms M0O3 while [(ÍÇ4)2è]ïïï83Ìïè3 and molybdenum suboxide (Ìïè3.÷, ÷=0.025) were obtained in the first and the second steps of thermal decomposition in He, respectively. Activation energies, frequency factors and kinetic model equations were determined for thermal decomposition reactions. Fractional conversion-time diagrams were compared with diagrams drawn according to kinetic model equation.IntroductionM0O3 is usually used as catalyst in industry [1]. AHM is the basic source to produce molybdenum containing catalysts used in petrochemistry [2]. The oxides of Li, V, W, Te, Bi and Sn are doped in M0O3 to produce catalysts, which find commercial applications in the industry. The properties of M0O3 are affected by dissolution, settling, calcination, drying and thermal decomposition processes [1]. There are several studies in the literature about the thermal decomposition of AHM and the characterization of the decomposition products in different gas atmospheres and at various heating rates [3-19]."

Jan 1, 2012

By Neil E. Izatt, Ronald L. Bruening, Steven R. Izatt

"IBC has developed environmentally friendly Molecular Recognition Technology (MRT) processes to selectively extract, recover, and purify a wide range of metals from a variety of process streams. The incorporation of MRT into process flow sheets can improve the economics of the processes. MRT separations are effective even at low (mg/L to \i%JV) metal levels. MRT processes are sustainable, being economically viable, energy efficient, and environmentally friendly as well as having a low carbon footprint. Examples of MRT processes will be presented and discussed involving platinum group metals, gold, rhenium, and other metals of interest to the mining community.IntroductionA significant portion of the earth's precious metal resources has been moved during the past century from underground to above ground [1]. This movement has important economic, health, environmental, ecological, and sustainability implications for the earth and its population. There is concern that recycling of certain precious and specialty metals from end-of-life (EOL) electronic wastes (e-wastes), catalyst wastes, mining waste streams, and other waste products such as rechargeable batteries is not adequate to maintain supplies of these metals sufficient for future needs [2-4]. Improved metal recycling rates and more efficient metal recovery from the enumerated wastes would significantly reduce the amount of virgin metals that must be mined to support our lifestyle [5]. More efficient separation procedures in ore processing flow sheets and more effective recovery of metals from low-grade waste streams would reduce metal loss in the mining industry."

Jan 1, 2012

By Jeong-Soo Sohn

Physical treatment and chemical treatment of spent lithium-ion battery were studied in our research team. Especially we developed two types of acidic leaching for crushed powders containing LiCoO2 of spent lithium ion battery. One of them is sulfuric acid leaching with H2O2 as a reducing agent. The leaching rates of cobalt, lithium and the other metals were above 99 % at the condition of 2 M H2SO4, 10 vol. % H2O2, 75 °C, 300 rpm agitation speed, 250 g/5L solid liquid ratio and 75 minutes reaction time. And the other leaching process is the oxalic acid leaching. In this process more than 99% of Li and less than 1% of Co were dissolved at the condition of 3M oxalic acid, 80°C reaction temperature, 300rpm agitation speed, 50g/L initial solid/liquid ratio and 90min extraction time. Each process has its advantage and disadvantage. In sulfuric acid leaching, leaching reagent is very cheap and cobalt could be recovered into cobalt hydroxide. On the other hand, oxalic acid is more expensive than sulfuric acid but lithium could be dissolved selectively. Also cobalt could be recovered into cobalt oxalate and it could be changed into cobalt oxide after heat treatment. In order to select the effective recycling process, recovery rate and purity of cobalt hydroxide and cobalt oxalate were compared and it was investigated which process was more environment-friendly and economical.

Jan 1, 2006

By Evan Jamieson

The conditions under which various iron(III) oxy-hydroxides phases precipitate from iron(III) chloride and sulfate solutions at ambient temperatures (<60°C) are reviewed. Many of these precipitates are slow settling and gelatinous but ultimately transform into other more stable or crystalline phases. The phase that forms depends upon the rate of precipitation and pH. A comparison has been made of the iron(III) oxides formed upon the neutralisation of various iron(III) solutions with caustic, slaked lime or slaked magnesia which provide different rates of neutralisation and slowly dissolving solids with localised high pH. Mössbauer spectra of ferrihydrites precipitated under these different conditions are compared and interpreted. Particular attention is paid to the settling rate and settled volume which is likely to relate to industrial thickener and filter performance. It is shown that in pure chloride solutions, poorly settling ferrihydrite is usually produced at 20oC regardless of the choice of base. However in sulfate solutions fast settling precipitates are produced using lime and magnesia but not with caustic. In mixed chloride/sulfate solutions, optimum settling rates occur when the molar ratio of [SO4]2to Fe3+ is about 1:1 and when the sulfate concentration is <0.20 M. It is proposed that ?dense amorphous basic iron sulfate? or well-ordered ferrihydrite is formed on slowly dissolving lime or magnesia surfaces. Implications for industrial liquors are considered.

Jan 1, 2003

By Yuhua Pan

Generic mathematical models have been developed for simulating heat transfer in two types of slag resistance heating electric furnaces for sulphide smelting: i) six-electrode-in-line rectangular furnaces and ii) three-electrode circular furnaces. The models are based on three-dimensional steady-state heat transfer of conduction, convection and radiation. Solidification of liquid slag into solid slag by water-cooling units, for use as freeze lining of furnace walls, is also considered in the models. The developed models are capable of providing predictions with reasonable accuracy for electric furnaces on 1) temperatures in slag, matte, cooling water, freeze lining and other solid regions as well as temperatures at various fluid/solid interfaces, 2) freeze lining thickness, 3) furnace smelting rate and 4) furnace heat loss rate. These computer models are built into executable application programs that are very efficient, with execution time less than one second, and can be easily portable to most computing platforms. This paper describes, as an example, the modelling results on heat transfer in six-electrode furnaces. The major modelling results show that in six-electrode furnaces uniform electric power inputs to the electrodes likely lead to low temperature regions close to slag and matte tapping ends of the furnaces, and the power input and the formation of air gaps between freeze lining and cooling units have significant influences on the thickness of freeze lining maintained by the cooling units.

Jan 1, 2006

By A. F. Usov

"The use of the Electric Pulse Discharge method of materials destruction (EP) for disintegration of materials in an industrial-waste processing are examined. The principles and Experience of the development device of EP-disintegration have been described, the technological efficiency of disintegration of industrial minerals estimated.IntroductionThe Russian scientists have proposed and comprehensively studied the electric pulse (EP) technique which is applied in ores and materials disintegration [1, 2 ]. The different aspects of the problem have been presented by the authors in papers at many international congresses [3-6]. Recently the technique is intensively developed in many countries, and various disintegration installations are exhibited.Crashing and disintegration of ores by EP-method is characterized by high selectiveness of destruction. It provides better disclosure of mineral grains and prevent it from destruction. EPmethod reduces slurry formation. All this provides better mineral extraction at ore beneficiation and improves concentrate quality. It also prevents the product from polluting with equipment metal, inwall and grinding equipment material. The possibility to change the character of dynamic loading allows controlling grain-size composition and getting small-size product in contrast to mechanical method of crashing.The product of EP-crashing is characterized by less toughness and greater specific surface area of grains since the new surface is formed at splitting and chinks extension. The product is of high sorption and reactivity in chemical changes. Open grains of mineral spots correspond to their natural condition and it is of great importance for studying mineral.The principles of the development deviceLong-term studies of the technique carried out by research institutes such as Research Institute of High Voltages (Tomsk), Kola Science Centre of RAS (Apatity), Institute ""Mekhanobr"" (S.Pertersburg), made it possible to substantiate principles of the disintegration installations design, make exploratory stands and technological installations to carry out pilot tests and operations under production conditions. The construction design of disintegrating installations depends on many technological and physical factors. Of all the technological factors, the most significant one is to preserve the liberated product because it is the peculiarity of the EPdisintegration to have high selectivity of disintegration. The preservation of the mono-mineral product liberated from the rock mass means that this product is not overgrinding, which causes the loss of the product with slime in processing, and that the initial natural form of the mineral inclusion is also preserved because it is the size and the integrity of crystals that determines its cost value (precious minerals). On the one hand, it is provided by a stage disintegration technique, with the product classified after each stage, and, on the other hand, by selection of specific conditions of electric breakdown, which ensure high performance of electric breakdown and effective disintegration of material fragments, with the useful mineral inclusions preserved intact, with its size considerably exceeding the discharge gap. These conditions are provided by the appropriate geometry of electrodes, the discharge gap and the screen size due to the material’s nature and grain size."

Jan 1, 2008

By L. Z. Villanueva

An investigation and evaluation has been performed to determine the potential utilization of electron beam irradiation technology for sulfur oxides removal from reduced-S02-strength metallurgical gases from copper smelters. These off-gases, though too weak to be converted to usable, concentrated: sulfuric acid by conventional means, are characterized by SO2 content higher than 2,000 ppm and a complex chemical composition, including high oxygen content and its generation occurring in a cyclical, fluctuating pattern. This work was based on information supplied by principal smelter companies in Chile. A laboratory facility with flow rate of 20 Nm3/h and equipped with an electron accelerator of beam energy 8.00 keV, has been used for testing. Influence on SO2 removal efficiency of operational parameters such as gas temperature, water vapor content, ammonia feed ratio and irradiation dose was established. The main conclusion of this work, from experimental laboratory tests as well as engineering studies, is that the Electron Beam Process (EBDS) is a cost-effective, simple and appropriate chemical process means for emission abatement. EBDS can, on a site-specific basis, adequately augment SO2 removal to upgrade overall abatement as required and in an optimal manner.

Jan 1, 1999

By M. J. Perpich

Electrochemical and chemical leaching tests were carried out on chalcocite, covellite and chalcopyrite in acidified iron sulfate solutions sparged with a mixture of O2 - SO2. The gas mixture catalyzed the ferrous to ferric oxidation reaction in situ and, therefore, increased the redox potential and oxidizing strength of the solution. Anodic polarization curves in dilute sulfuric acid on copper sulfide electrodes showed that chalcopyrite passivates and dissolves at current densities orders of magnitude less than chalcocite and covellite. The addition of a depassivating agent (Ag+) increased the passive current density of chalcopyrite and caused breakdown near 0.625 V (SCE). The depassivating effect was also observed during the leaching of chalcopyrite particulate samples as small amounts of Ag+ added to acidified iron sulfate solutions in the presence of O2 - SO2 mixtures greatly increased the leaching rate and the total amount of Cu oxidized (> 90%). Passivation was prevented in the absence of Ag+ by decreasing the initial oxidizing power of the solution and by pretreating the sample in a reductive leach. Both of these methods resulted in transformation of the chalcopyrite surface from its characteristic greenish-gold into deep black. Increased concentrations of Fe+++ due to 02 - S02 sparging were then able to oxidize the transformation product.

Jan 1, 1999

By C. G. Anderson, L. G. Twidwell

"Throughout the world, there are many orebodies or materials which have significant value but also contain arsenic, antimony, and mercury. As regulations on the transport, exposure, disposition and emission of these elements have become more stringent; it has become increasingly more difficult to derive the values from the resources. This paper outlines the fundamentals of alkaline sulfide hydrometallurgy and its successful application to arsenic, antimony and mercury bearing ores, concentrates, by-products, and other materials.Fundamental Alkaline Sulfide HydrometallurgyHydrometallurgical methods can be employed for treatment of gold, arsenic, antimony, tin and mercury containing materials, concentrates and ores as well as complex ones containing any number of metals. The alkaline sulfide system is one of these and is essentially a mixture of sodium sulfide and sodium hydroxide. This is a unique hydrometallurgical system as it is a very selective lixiviant for the distinct leaching of tin, gold, antimony, arsenic and mercury [1-7]. Worldwide, it is employed industrially in the CIS, China and the United States for the production of antimony [8-15].As an example, when the system is applied to an arsenic containing material like orpiment, As2S3, a solution of sodium thioarsenite is formed. This is illustrated as:"

Jan 1, 2008

By A. S. Mustafinova, A. A. Zharmenov

"Production of electrolytic copper is characterized by large volumes of acidic spent solutions the utilization of which requires considerable expenditures of neutralizing agents. At present, an economically substantiated technology does not exist for treatment of sulfuric acid rinse solutions and spent copper electrolyte which will allow for repeated use of the acid and the metal salts. Therefore, for this aim the most advantageous is the use of electromembrane methods. In the paper there is stated the essence of developed technologies which are distinguished by low waste and provide the extraction from the solutions of metallic copper, nickel and sulphuric acid. There are also considered methods of copper electrolyte processing allowing to regulate its composition by that or another component (H2S04, Cu, Ni, As).On the base of the detailed study of the behaviour of various types of ion- exchanger membranes in copper-, nickel-, zinc-, arsenic- bearing sulphate solutions there is realized the selection of the most suitable membranes (MK -401, MA-411, MB-2 and MKL-l/MAL-2).Some variants of electro membrane processing of spent solutions of the hydrometallurgy process have passed productions tests on a number of copper-electrolyte enterprises of the countries of CIS (cooperation of Independent States). These tests showed high efficiency of developed methods."

Jan 1, 1997

By Yongxiang Yang

High temperature processing of raw materials in metals production and recycling often involves complex multi-phase fluid flow and heterogeneous chemical reactions at various scales. Good understanding of the process physics and chemistry is crucial for process operation and process development. The traditional scale-up process through laboratory scale ? pilot scale ? commercial scale route has been more and more complemented and partially replaced by full-scale process simulation. Computational fluid dynamics (CFD) has become a very useful simulation tool in process research and development. At the same time industrial applications challenge the CFD development with its complex transport phenomena, often in large-scale reactors with small-scale physics and chemistry. The current paper discusses the applications of CFD to a number of high temperature metallurgical and materials processing applications. The research was carried out by using commercial CFD codes as the framework, and the emphasis was given to the special efforts for the development and implementations of sub-models with process-dependent physical and chemical characteristics. To illustrate the application of CFD simulation to high temperature metallurgical processes and coupling of sub-models to the general-purpose CFD codes, five examples are given: (1) melting of aluminium scrap in a rotary furnace for recycling, (2) molten hot metal flow in a heterogeneous coke-bed of a blast furnace hearth, (3) gas flow heat and mass transfer in a submerge electric arc furnace for phosphorus production, (4) high temperature incineration of hazardous waste in a rotary kiln, and (5) transient heating of metals in heat treatment furnaces.

Jan 1, 2006

By Qin Hua, Xiangru Chen, Qijie Zhai, Yongsheng Yan, Liang Chang

"In this paper, pure bainite ductile iron and their alloying form of 0.2wt% niobium were prepared by a controlled cooling heat-treatment. The effect of niobium alloying on the microstructure, hardness and impact toughness of bainite ductile iron was studied. The results show that adding niobium effectively improves the hardness and toughness of bainite ductile iron. The hardness and the impact toughness of niobium-alloyed bainite ductile iron were investigated by varying the temperature at which samples were fed to the incubator.IntroductionThere are two essential methods to prepare the bainite ductile iron: isothermal quenching [I-31, and alloying [4• 51• Isothermal quenching process is very time and energy consumable, concerned as a high cost technique for mass production. Besides, there are certain limitations on the size and shape of castings in this process. In addition, it potentially harms the environment. As for the alloying, Ni, Mo, and Cu have to be utilized to obtain bainite. However, the large demand and high cost of Ni makes it not feasible in practice.It is well known that niobium can promote the formation of carbon compound, and improves the stability ofundercooled austenite, which is preferred to the increase of the hardenability. Previous studies showed that niobium could refine the grain and improve the mechanical properties of gray cast iron [6-81 • Therefore, in the present work, the effects of niobium and the temperature at which samples were fed to the incubator on the microstructures and properties of niobium alloyed bainite ductile iron were investigated."

Jan 1, 2014

By Karl-Michael Zett, Marcus Kirschen, Ashraf Hanna

"Bottom purging systems are well established practice in refining metallurgy and an increasingly important technology for the EAF process in steel industry. Direct bottom purging provides efficient mixing of the entire melt volume, increases turbulence intensity in the melt, and improves mass exchange of alloy additions or oxygen. Continuously rising columns of dispersed gas bubbles helps to increase removal of volatile components carbon monoxide and hydrogen avoiding boiling retardation. Direct purging (DPP) systems provide cost benefits especially for EAF processes where metallurgical constraints have to be considered, e.g. for alloyed and stainless steel production, foundries. Case studies are presented.IntroductionCurrent EAF Technology and Production Constraints in Steel IndustryApproxinlately 30 % of steel, 446 Mio. tonnes in 2011, was melted in the electric arc furnace (EAF) with increasing tendency due to its large flexibility in production volume and raw materials. With recent increase of prices for ferrous raw materials the requirements for production of high quality steels from low quality scrap, direct reduced iron (DRI) and blends of ferrous raw material in various qualities increased. Maximum yield of ferrous raw material, oxygen, carbon, and alloys and minimum energy costs are of high importance. At modem high productivity levels even small process improvements provide considerable cost savings. Such improvements are caused, e.g., by efficiency increase of mass and energy transfer in the EAF. Optimization of flow pattern in the steel bath is therefore important for efficient melting of scrap and DRI and high homogeneity of the melt [1-4]."

Jan 1, 2013