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By Peter Kong

This paper provides a general discussion of atmospheric-pressure plasma generation, processes, and applications. There are two distinct categories of atmospheric-pressure plasmas: thermal and nonthermal. Thermal atmospheric-pressure plasmas include those produced in high intensity arcs, plasma torches, or in high intensity, high frequency discharges. Although nonthermal plasmas are at room temperatures, they are extremely effective in producing activated species, e.g., free radicals and excited state atoms. Thus, both thermal and nonthermal atmospheric-pressure plasmas are finding applications in a wide variety of industrial processes, e.g. waste destruction, material recovery, extractive metallurgy, powder synthesis, and energy conversion. A brief discussion of recent plasma technology research and development activities at the Idaho National Laboratory is included.

Jan 1, 2006

By Young-Geun Park

A new decarburization model for the RH system was constructed for calculating the decarburization reaction using a three-dimensional fluid dynamics program. The entire fluid flow in the RH process was calculated by evaluating the shape and volume of the plume zone, formed by Ar gas blown through multiple nozzles on the wall of the snorkel. On the basis of this fluid flow, the decarburizaiton reaction was calculated through establishing the decarburization reaction model, which considers the thermodynamics, reaction kinetics, and the decarburization sites (Ar bubble surface, bath surface, and the CO bubble fomtation at inner sites). The results from this model were compared with a real RH operation results with good agreement. Because it is possible to predict the carbon concentration at various conditions using this model, it may be useful in increasing the decarburizaiton rate. Key words : RH process, plume zone, decarburization, Ar bubble surface, bath surface, inner site, circulation flow rate.

Jan 1, 2001

By Larry Hopkins

The molten metal circulation pump has become a staple for melting aluminum in reverberatory furnaces. The forced convection that is created in the melt efficiently provides circulation while dramatically improving melt rates, lowering fuel consumption, extending refractory life, and providing metallurgical homogeneity. Two metallurgical guidelines that are important to many casthouses are molten metal inclusion levels and hydrogen gas content. In order to improve molten metal quality, furnace and casting practices must 'manage these molten metal defects, Today specialized in-line degassing and filtration equipment is used downstream of the furnace to accomplish these tasks. In contrast, the molten metal gas injection pump has metallurgical contact time in the process for hours during the charging/homogenization cycle. The qualitative benefits of employing a gas injection pump to "pre-clean" are outlined and discussed against historical empirical information obtained with alternate methods. Further, a recent study quantifies the merits of this gas injection technique as an effective molten metal quality improvement tool. Specifically, the effects on inclusion level as determined by PoDFA?, gas content as determined by A1SCAN? sampling and alkali metal content as determined by spectrographic analysis are examined in relationship to various gas feed compositions and flow rates.

Jan 1, 1995

By John J. J. Chen, Barry J. Welch

"As in many industrial processes, the detailed mechanisms involved must first be understood before being able to redesign, or to carry out improvements or optimisation of the process and equipment performance. In a great majority of metallurgical processes, visual observation and actual measurement of process variables are either very difficult or near impossible. Often, the cost and effort involved are prohibitive. Consequently, physical modelling is often used to provide some understanding of the process and for the validation of computer numerical models. In this paper, we summarise some of the work carried out at The University of Auckland on the modelling of the Hall-Héroult electrolytic cell, the in-line melt treatment process, and the steel casting tundish. IntroductionIn any industrial process, it is essential to understand the underlying mechanisms before any optimization or process improvement can be carried out. In many metallurgical operations, the processes are conducted at elevated temperature and under rather hostile environments. Consequently, it is often difficult, and sometimes impossible, to observe the actual processes occurring, or conduct measurements which are pertinent. In some situations, it is possible to formulate mathematical equations purported to describe the process, and obtain the solutions numerically. However, in this latter case, the validity of the simplifying assumptions made are often uncertain. Physical modelling may provide the necessary information for the validation of such numerical models. Furthermore, through an application of the principle of similitude, it is possible to apply data obtained from physical modelling to actual metallurgical processes. This paper will summarise some the work carried out at The University of Auckland on the physical modelling of gas-induced flow in the Hall-Héroult electrolytic cell, an in-line melt treatment unit, and the flow in a steel casting tundish.Gas-Induced Flows in a Hall-Héroult CellIn an aluminium cell, the effects due to electro-magnetic forces have been addressed and various design modifications such as magnetic shielding and the positioning of risers have been carried out to control or lninimise the effects of magnetic fields'. Consequently, the effects of gas-induced flows are now becoming significant providing the impetus for the study of the gas behaviour in the bath. Furthermore, the shape and size, and the rate of evacuation of the anodically generated gases affect the cell voltage affecting the energy efficiency; at the same time, the back-reaction between the anode gas and the metal produced is the predominant cause of the loss of current efficiency. Figure 1 shows a cross-section of a conventional cell in which the gas evolution occurs directly under the anodes, and the gas induced flow is confined mainly to the region occupied by the bath"

Jan 1, 1994

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 M. Y. Mohassab-Ahmed

In an effort to develop a novel flash ironmaking process, the chemistry of selected slags was investigated. In different ironmaking processes, the molten bath (iron-slag bath) is expected to be in contact with gas atmospheres of H2/H2O, CO/CO2/H2/H2O, and CO/CO2. The latter was investigated to allow comparison with the blast-furnace conditions. The slag composition was selected to resemble that of the blast furnace with CaO/SiO2 in the range 0.8 to 1.4. The temperature range was 1550 to 1650°C. The oxygen partial pressure was maintained in the range 10-10 to10-9 atm. The effect of water vapor on the chemistry of the slag as well as the equilibrium reactions involving the slag has been studied for the first time. H2O dramatically affects the chemistry of the slag and strongly affect the phase equilibria in the slag as well as the equilibrium distribution of elements between slag and molten metal.

Jan 1, 2014

By Drew Sinha

Success of the environmentally benign semiconductor manufacturing depends on the cost-effective integration of the principles of reduce, recover, reuse and recycle from source material to final product disposal. Increasing demand combined with current shortage of polysilicon provided unique opportunities to recover the silicon waste, caused by various defects, in wafer manufacturing process. Current practices relating to recovery and reuse of waste silicon produced, from crystal growth process to finally polished and epitaxially deposited silicon wafer, at Mitsubishi Silicon America is presented. Future plan to recycle the process generated silicon fines produced during the intermediate steps of the wafer manufacturing process such as grinding, slicing, lapping and polishing is also discussed.

Jan 1, 1998

By May Nyman

Due to the vast diversity of chemical media in which metal separations are executed, a wide range of ion separation materials are employed, This ,results in an ongoing effort to discover new phases with novel ion exchange properties. We present here the synthesis of a novel class at, thermally and chemically stable microporous, niobate-based materials. Ion exchange studies show these new phases are highly selective for Sr2+ and other bivalent metals.

Jan 1, 1999

By Fujio Ishii

The deoxidation of liquid nickel and nickel binary alloys with silicon has been determined at temperatures between 1500°C and 1650°C using quartz crucibles in order to investigate the deoxidation of nickel based alloys. The equilibrium constant of the deoxidation reaction in liquid nickel and the effects of the different alloying elements such as chromium, molybdenum, tungsten, iron, cobalt and coppcr on the activity coefficient of oxygen in liquid nickel have been established.

Jan 1, 1993

By R. J. St. Eloi

The Kidd Creek Copper Smelter has been expanded from its original design of 59,000 tonnes of copper per year to over 120,000 tonnes per year .. Modifications to the process gas handling system and acid plant have been made to accommodate this higher production rate and to .generally optimize the operation. The gas handling system associated with the continuous smelting process is discussed in terms of boiler accretions and modifications to minimize their impact on operations; design changes to effect reductions in high pressure drop duct configurations; material changes to overcome corrosion and plant additions to 'improve gas cleaning capability. The acid plant is reviewed with references to changes made to accommodate the increased S02 gas strength resulting from the higher smelting rates;

Jan 1, 1992

By Z. W. Zhang, Songsong Xu, Jinhui Li, Yun Zou, Yu Zhao

High strength low alloy (HSLA) steels with high strength, high toughness, good corrosion resistance and weldability, can be widely used in shipbuilding, automobile, construction, bridging industry, etc. The microstructure evolution and mechanical properties can be influenced by thermomechanical processing. In this study, themomechanical processing is optimized to control the matrix microstructure and nano-scale precipitates in the matrix simultaneously. It is found that the low-temperature toughness and ductility of the steels are significantly the matrix microstructure during enhancing the strength by introducing the nano-scale precipitates. The effects of alloying elements on the microstructure evolution and nano-scale precipitation are also discussed.

Jan 1, 2016

By I. Gaballah

The kinetics of oxychlorination of pure CI-2O3 with C12+02 gas mixtures is studied by ThermoGravimetric Analysis (TGA) in non and isothermal conditions up to 1000 °C. The reaction of Cr2O3 with C12+O2 chlorination gas mixtures starts at about 550 °C and the reaction product is CrO2Cl2. The oxychlorination rate of Cr2O3 is almost proportional to the chlorine partial pressure and to the fourth root of the oxygen partial pressure in the chlorinating gas mixtures. At 800 °C, the maximum chlorination rate is obtained using a gas mixture having a C12/O2 ratio equal to 4. The apparent activation energy of the oxychlorination reaction of Cr2O3 is 87 and 46 kJ/mol at temperatures lower and higher than 650 °C, respectively. By varying the chlorine and the oxygen partial pressures of the oxychlorinating gas mixtures at temperatures higher than 550 °C, it is possible to extract selectively the chromium chlorinated compounds from the chromium bearing materials. a. Laboratoire Environnemem et Minéralurgie, BP 40, 54501 Vandceuvre, France, b. École Nationale Supérieure de Géologie, Rue du Doyen Marcel Rouhault, 54501 Vandoeuvre Cedex, France, c. Centre National de la Recherche Scientifique, 3 rue Michel - Ange, 75794 Paris Cedex, France, d. Insritut National Polytechnigne do Lorraine, Rue de la Font de Haye. 54501 Vandceuvre Cedex, France.

Jan 1, 1997

By K. J. Murphy, A. R. Smith, A. P. Odorski

"The need for large quantities of oxygen for use in metallurgical processes was a major driving force in the commercialization of tonnage air separation plants. Oxygen, nitrogen and argon impact the quality, energy efficiency and environmental aspects of metals production. Cryogenic air separation processes have been used to supply most industrial requirements, however, newer technologies are available or under development to meet the needs of today's and tomorrow's metallurgical processes. This paper reviews the technical features and state of development of adsorption, chemical, cryogenic and membrane technologies. The technologies are compared in terms of plant size, oxygen purity and pressure, nitrogen and argon co-production, product use pattern and back-up requirements. Computer control systems are described that optimize operation over varying load patterns and ambient conditions; substantially lowering energy consumption. IntroductionOxygen production totalled 390 billion cubic feet in 1987. Although current production is lower than the peak of 455 billion cubic feet reached in 1979, oxygen remains the fifth leading chemical product manufactured in the u.s. (1) Metals manufacturing and fabrication accounts for sixty percent of the oxygen consumed in the u.s. Oxygen use in the steel industry consists of air enrichment for conversion of iron ore, purification of the iron in basic oxygen or other furnaces, and for cutting and welding the finished steel product. Nonferrous ores are smelted in oxygen enriched atmospheres to reduce energy consumption and increase capture of sulfur compounds to meet environmental requirements. In the future oxygen usage is expected to become even more important in metals production as energy costs increase, environmental standards become more stringent, and as new coal based processes become commercialized. Oxygen usage per ton of metal in the new direct reduction processes can be up to ten times higher than traditional steel making."

Jan 1, 1988

By M. R. Baren

Unpublished results obtained by Baren on thermodynamic properties of sulfur in liquid Fe. Co. Ni. Fe-Co. Fe-Ni. and Co-Ni are reevaluated. correlated. and interpreted on the basis of recent developments in thermodynamics of alloys:. Existing reliable data are reviewed and compared with the? present results. Sulfur obeys Henry's law up to 0.04 mol fraction. and in this range the standard Gibbs energy of solution of sulfur is expressed as a linear function of temperature for each pure metal. The activity coefficient of sulfur in each binary metal solvent 1s correlated with the composition of alloy.

Jan 1, 1983

By Minting Li, Hailong Yang, ChangWei, Cunxiong Li, Gang Fan, Xingbin Li, ZhiganDeng

The filtration problems on acid leaching sludge of high silicon zinc ore have been paid extensive attention in zinc hydrometallurgy. It was found that soluble silica can be effectively converted into silica precipitate with good settling, filtration and washing properties, and the filtration rate can be in excess of 800 L/m2 · h under certain leaching conditions. According to investigating on the filtration rate, viscosity and concentration of silica of leaching sludge or liquor, the filtering temperature can tremendously improve the filtration property of pulp. At the same time, the experimental data indicated that the viscosity of leaching liquor was the key factor influencing filtration property of leaching sludge.

Jan 1, 2016

By Jagdish C. Agarwal

Although copper ranks very low in the order of abundance of elements in the crust of the earth, it has been one of the first metals utilized by mar, at his emergence from the Stone Age, about 10,000 years ago. Use of copper for weapons, tools, utensils and ornaments dates back to the twilight of history, 6,000-5,000 B.C. Native copper outcrops and the malleability of the metal explain its very early use by the cave-dwellers. The working, melting and extraction of copper from its minerals are among the oldest metallurgical achievements of the human race. The oldest complete smelting installations for the extraction of copper from its minerals, dated about the fourth millenium B.C., were recently discovered in the Timna Valley, Wadi Arabah, Israel. (1) The history of the developments of the extractive metallurgy of copper has been adequately reviewed recently. (2,3) The center of copper production migrated from the Eastern Mediterranean to Northern Europe (Mansfeld, Germany, Swansea, Wales) towards the end of the Middle Ages (1500 A.D.). The production of the metal was boosted tremendously in North America since the end of the nineteenth century (Fig. 1).

Jan 1, 1976

By Bora Derin

The partial pressure ratios of sulfur and oxygen for several copper flash smelting plants were derived using the Reddy-Blander (RB) model and predicted dissolved sulfur contents available in the literature. The sulfide capacities (Cs) of six different flash smelting plants (FeO-CuO0.5- CaO-MgO-FeOwAIOl.s?SiO2) slags were calculated. The log (Po2/PS2) versus matte grades of various industrial processes was determined. The PoiPS2 ratio increased with an increase of copper grade. The calculated partial pressure ratios for the copper flash smelting are in good agreement with those of the experimental data.

Jan 1, 2003

By Chengyi Ding, Xuewei Lv, Changyang Ji, Rende Zhang, Xiangwei Zheng

Inexpensive and high-quality sinter has an extraordinary position in iron making, and there are many factors influencing the sintering. This research takes the basicity and coal dosage as research subjects to do the experiments based on cost analysis with sinter pot experiment system. Linear program is taken to make the schemes of ore blending. During the experiments of changing basicity from 1.6 to 2.3, the properties and microstructures of the sinter are studied. It comes to a conclusion that increasing the basicity is beneficial to sinter quality but leads to higher cost. To further ascertain the cost of sinter and the potential of saving coke, the work of improving coal dosage is taken on the basis of experiments of changing basicity. Through analyzing the results, a formula (Y=1849+261.1R-130.6C) is proposed which indicates the relation among the cost, basicity and fixed carbon content. And it works well for actual production.

Jan 1, 2015

By Mark Cross, Diane McBride, Nick Croft

Extractive metallurgical processes rate amongst the most complex from the perspective of computational modeling. They typically involve multi-phase and multi-component fluid flow in very complex geometries, heat transfer driven by a number of interacting phenomena, solidliquid- gaseous phase change and mass transfer together with complex thermodynamics and associated chemical reactions. Beyond the model building itself, key challenges have always involved being able to identify the phenomena present together with interactions to characterize processes and experimental laboratory and plant data to parameterize the arising models – it is in this milieu, which require considerable process understanding and subtlety of thought, that David Robertson has made his contributions. We will review the achievements, over the last couple of decades, in computational modeling of extractive metallurgical processes and address some of the remaining challenges to enable simulation based process design, as we move through the 21st century.

Jan 1, 2014

By D. J. Murdock

Cominco Ltd. has developed a number of innovative technologies for electrowinning. The paper discusses the application of these technologies to the copper industry. Tankhouse and cell design will be discussed in addition to anode cleaning and cathode handling. Specific examples of the application of this technology to the copper industry are cited.

Jan 1, 1987