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By Jean-Pierre Birat, Ana-Maria Iosif, Denis Ablitzer, Olivier Mirgaux

"Integrating environmental considerations into the product traditional process design is now the major challenge for steel industry. Life Cycle Assessment (LCA) is nowadays considered as an appropriate method for assessing environmental impact and selecting new technologies to reduce CO2 emissions for steel industry.In this paper we propose a new methodological concept which combines LCA thinking with process simulation software in order to carry out the life cycle inventory of classical steelmaking process.Using Aspen PlusTM software, a physicochemical model has been developed for the integrated steelmaking route. This model gives the possibility to carry out life cycle inventories for different operational practices in order to optimise the use of energy, to calculate CO2 and other emissions and to control the mass and the heat balances of processes.It is also shown that such approach can be used to design and assess new technologies for steelmaking without large industrial application.IntroductionDuring recent years, it was recognised that CO2 emissions are the major factor of the global warming effect. In order to meet Kyoto requirements, the steel industry is embracing the challenge of sustainable development by improving its competitiveness and economic success while reducing its environmental impacts. Integrating environmental considerations into the traditional product design process, for powerful eco-efficiency, is now one of the major priorities for steelmakers.The European Steel Industry has measured up to this challenge by creating ULCOS (Ultra Low CO2 Steelmaking) consortium that has taken up the mission to develop breakthrough steelmaking process with the potential to reduce CO2 emissions (Eurofer, 2005). In order to develop technologies to reduce emissions, it is necessary to assess the environmental impact of the classical steelmaking route (coke plant, sinter plant, blast furnace, basic oxygen furnace, continuous casting and hot rolling)."

Jan 1, 2009

By J. H. Corrigan

A series of six papers describing the Falconbridge Dominicana Ferronickel project were presented at the International Laterite Symposium held as a joint project of TMS-AIME in February 1979 at New Orleans. A review of the ore mineralogy, as well as. the processing and environmental practices as they exist today at Falcondo with emphasis on modifications put into practice since 1979 are presented in two papers: Part I.- Mineralogy and Ore Dressing E.W. Lithgow - General Superintendent ? Mines Falconbridge Dominicana, C. por A. Bonao, Dominican Republic Commercial volumes of nickeliferous laterite ores overlie part of a 90 km long belt of peridotites in central Dominican Republic. Protores are serpentinized harzburgites and dunites, with lesser serpentinite. The ore mineralogy consists mostly of goethite, serpentine-group minerals, quartz and poorly crystallized, X- ray amorphous materials. Minor constituents are hematite, gibsite, olivine and enstatite. In the Ore Dressing plant, the mine feed is subjected initially to proper sizing and blending to produce a homogenized mix. Subsequent drying and upgrading, by selective crushing and screening of rock kagments through a Barmac circuit, complete preparation of the ore for pyrometallurgical processing. Part II.- Pyrometallurgy, Fuel and Power Generation J.H. Comgan - Manager ? Production Falconbridge Dominicana, C. por A. Bonao, Dominican Republic Falcondo's energy requirements are based on oil which is refined on site to provide distillate to carry out drying and selective reduction of the nickeliferous ore in the shaft furnaces, plus bunker oil to produce electrical power for process melting, refining and ancillary use. The dryer product at 1.68% Ni is briquetted and passed counter current to hot reducing gas in 12 vertical shaft furnaces. The hot calcine discharge is melted in two high power electric furnaces at very high secondary voltage. The crude ferronickel is ladle refined and cast as 15 kg ingots or 125 gm ferrocones.

Jan 1, 1993

By S. Tandon

Equilibria studies of selenium distribution for sodium-borate slags were initiated at 1473k under reducing condition as a function of slag composition and alloy composition. The Se distribution coefficient (% Se in slag/% Se in metal) increased from 0.4 to 2.9 with increase in basicity (0.53 to 0.86) for Cu-0.446% Se alloy. However, the results are not very useful from industrial application viewpoint. Therefore, in order to improve the distribution of Se, CaO (10% to 50%) was added to the sodium-borate slag of basicity 0.864. On addition of 502 CaO, the distribution coefficient increased roughly by 100% for slag composition - 44.5% Borax, 22.2% Na2C03, 33.3% CaO and Cu-0.44677 Se alloy. Further, the value of this distribution coefficient has been found to increase by an additional 80% on addition of 20% CaF2 to the above slag for all Cu-Se alloy compositions. Also with increase in initial concentration of Se, the distribution coefficient has been noted to increase.

Jan 1, 1992

By Guanyong Shi, Zhihe Dou, Cong Wang, Ting'an Zhang, Hongyan Zhang

We prepared the CuCr alloy by thermit reduction-electromagnetic casting. But there are the defects such as stomata and oxide inclusions in CuCr alloy. In this paper, the existing state and distribution of inclusions and stomata in CuCr alloy are systematically analyzed. The alloy was characterized via SEM, EDS and metallographic microscope, in which the existing state and micro-structural defects of inclusions are analyzed. The results show that: there are three distinct areas: copper-rich areas, chromium-rich areas and the inclusion areas. Inclusions are mainly in the form of stomata and Al2O3 phase, mainly locating in the copper-rich phase and the interface area of chromium-rich phase and the copper-rich phase. Then, the composition of phases of the smelting slags and alloy were characterized via XRD. The results show that: the slag consists of Al2O3 and a little of Cr, the alloy consists of Cr, Cu and a little of Al2O3.

Jan 1, 2015

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 François Tremblay

It is well known that removal of organic material such ,as Jacquer, paint, plastic prior to melting improves aluminum recovery. In addition to being an important economically, decoating of aluminum scrap has a positive impact on the environment, through better control of gaseous emissions. Most of the existing thermal decoaters for aluminum have been designed to operate with scrap containing a level of organic material lower than 10%. The main field of their present application is for recycling of used aluminum can, where levels of organic material are lower than 4%. Alcan has recently developed a new thermal decoating system in order to extend applications of this process to a much wider variety of aluminum scrap. The new decoater efficiently processes aluminum scrap with a level of organic material up to 50%. This new technology features the use of fluidized bed technology to thermally control the process. This innovative feature improves both performance and control over conventional delacquering systems based on hot air convection. This paper describes the basic principles of the technology and the design of the? first industrial unit commissioned by the Alcan Recycling plant in Shelbyville (TN) at the beginning of 1994. Typical applications and operating advantages are discussed.

Jan 1, 1995

By Kenneth L. Driggs

The Environmental Protection Agency's Clean Air Act of .1970 provided the driving force for the current Magma Smelter configuration. The historical and technical perspectives of those process developments are reviewed. Innovations in procedures and equipment have allowed compliance with the requirements of the regulating authorities. The wet scrubbing of converter gasses and the monitoring of converter operations by a controlling foreman are two of the major contributors to these successes. The Clean Air Act Amendments of 1990 have posed many new concerns for all U.S. industry, including the few (seven) primary copper smelters remaining. Future concerns include tightening the sulfur dioxide ambient standard from the current three-hour averaging period to one hour"

Jan 1, 1992

By William Petruk, J. H. Gilles Laflamme, Jean Robitaille, Louis J. Cabri

"A quantitative mineralogical study using ore microscopy, electron microscopy, proton-microprobe, image analysis, and material balances was done on samples from the circuit of a concentrator in Quebec, with particular emphasis on the Cu concentrate. The ore contains many different minerals, of which the principal ones, in decreasing order of abundance, are pyrite, sphalerite, chalcopyrite, bornite, galena, tennantite, and pyrrhotite. Minor to trace amounts of covellite, chalcocite, stannoidite, mawsonite, colusite, wittichenite, miharaite, hessite, petzite, electrum, and an unidentified Cu-Pb-Bi-sulfide also occur.Liberation of pyrite is very high in all size fractions for all samples (ranging from 80-91 %). Liberation of chalcopyrite, bomite, sphalerite, and tennantite is relatively high, on average, in the head .sample and Cu concentrate (55-78% and 66-88%, respectively). Most of the chalcopyrite in the flotation tails is not liberated, whereas about one half of the tennantite and sphalerite are liberated in both the flotation and :final tails. Recoveries calculated for the Cu concentrate (on the basis of assays, mineralogy, and image analysis) are chalcopyrite 72. 5%, bornite 73. 7%, sphalerite 41.0%, tennantite 70.9 %, and galena (together with some trace minerals) 34.2%. It was also calculated that the Cu concentrate contains 10.0 % of the pyrrhotite and i.4 % of the pyrite.Materials balance calculations were done on the five major sulfide minerals to determine the mineralogical distribution of 13 major, minor, and trace elements (as determined by protonmicroprobe analyses). It was determined that tennantite is the principal carrier of Bi (67%), As (90%), and Te (86%) in the Cu concentrate. Therefore, removal oftennantite, which is mostly liberated in the Cu concentrate would significantly reduce these three contaminant elements, but at a loss of9% of the Cu, 2.0% of the Zn, and 0.7% of the Ag. The precious metals (Au, Ag) occur as discrete minerals (electrum, petzite, hessite). Some of the Ag also occurs in solid solution in bornite (23.1% of Ag in Cu concentrate), tennantite, and sphalerite. Four of the major sulfides (chalcopyrite, bomite, sphalerite, tennantite) in the ore also contain measurable concentrations of the following trace elements: Se, Cd, In, Sn, and Sb, occurring mostly as solid solutions. Some of these elements are also concentrated (up to about 18%) in minor and trace minerals such as colusite, stannoidite, and mawsonite."

Jan 1, 1999

By J. M. Demarthe

MINEMET RECHERCHE (IMETAL Group, formerly Le Nickel-Penarroya-Mokta) has studied on a laboratory scale and patented a new process to recover metal values -copper- from sulphide ores and concentrates. It combines a cupric leaching, solvent extraction and copper sulphate electrowinning according to the main following steps - A direct and selective leaching of copper sulphide ores or concentrates at atmospheric pressure with cupric chloride to form cuprous and ferrous chlorides and elemental sulphur. Pyrite remains in the sulphur residue. - The leach solution is separated into two parts -In the first one, air is injected to precipitate iron as goethite. The oxidation step can be easily realized at atmospheric pressure by maintaining an excess of cuprous and-ferrous chlorides in the liquor. Copper is extracted from the second part as cupric ion by an LIX reagent. Direct injection or air in the mixing chamber maintains good extraction conditions, so that only one mixer settler is required. - Iron, in the form of ferrous ion, is not coextracted. - Copper is stripped from the organic phase, transferred into a sulfuric phase and sent to sulphate electrowinning cells, which are now conventional in copper metallurgy. - Only electricity and air are required. After a feasibility study, the next step will be to develop it on a pilot and commercial scale.

Jan 1, 1976

By A. Onozaki

The Iijima Refinery was put into operation in 1972 and today has an annual production capacity of 156,000 tons of SHG electrolytic zinc. At the Iijima Refinery, the recoveries of gold and silver are 98.0% and 98.2%, respectively. Gold contained originally in the zinc concentrates reports in the Cu-Pb-Ag residue produced in the residue treatment process. Silver contained in the concentrates is distributed between the Cu-Pb~Ag residue and the copper cake produced in the purification process. The Cu-Pb-Ag residue, which contains gold and silver, is sent to the Oyachi flotatfon plant of the Kosaka Smelter; about 82% of the gold and about 85% of the silver are recovered in the copper flotation concentrate.. In this paper, the distribution of gold and silver in the Iijima. Refinery is discussed and operational results of the Oyachi flotation plant are presented.

Jan 1, 1990

By S. Viswanathan, A. S. Sabau

"Dimensional changes between a pattern die and its corresponding investment casting part occur as a result of complex phenomena such as thermal expansion/contraction and hot deformation (elastic, plastic, and creep) during the processing of the pattern material (wax), mold material (shell) and solidifying alloy. Determining the pattern tooling dimensions is crucial to the dimensional control of the investment casting process. To date, computational methodologies have not been applied to the prediction of dimensional changes in investment castings.This paper deals with the evaluation of wax pattern dimensions, which is one important factor in determining pattern tooling dimensions in investment casting. Cerita 29-51, an industrial wax, is considered in this study. The wax pattern dimensions are determined by considering its thermo physical and thermomechanical properties, restraint of geometrical features by the metal die, and process parameters such as dwell time, platen temperature, injection pressure, and injection temperature.IntroductionThe investment casting process involves making a disposable wax pattern by injecting wax into a metal mold, building a ceramic shell mold around the wax pattern by the application of a series of ceramic coatings to the wax pattern, dewaxing the ceramic shell mold, and casting the alloy into the shell mold. Dimensional changes between the pattern tooling and its corresponding cast part occur as a result of thermal expansion, shrinkage, hot deformation, and creep of the pattern .material (wax), mold material (shell), and solidifying alloy during the processing [1]."

Jan 1, 2001

By Y. A. Chang, J. Woodford, C. R. Kao

Reactive diffusion studies between NbC and Si were carried out at 1300 °C under a vacuum of 10-5 torr and a uniaxial pressure of 1 MPa. The annealing time ranged from 8 to 100 hours. The Si used was single crystal silicon; the NbC was hot-pressed powder compact. A NbSi2+SiC two-phase reaction layer formed with NbSi2 as the matrix and SiC as discontinuous particles. The microstructure of the reaction product is homogeneous, dense, and fine. The NbSi2 grain size and SiC particle size are in the micron range. The growth of the reaction products follows parabolic kinetics. Extrapolation of the data to zero thickness suggests an apparent incubation time of 3.5 hours. However, for short annealing time «60 hours), the thickness data can be approximated by linear kinetics with an initial growth rate of about 2 11m/hr. Based on these experimental observations, a growth mechanism for the reactive diffusion between Si single crystal and NbC powder compact is proposed. We propose that the nucleation sites for the SiC particles are at the voids of the NbC powder compact. This proposed nucleation mechanism offers a potential way of controlling the SiC particle size by changing the void size and void density of the NbC powder compact. This hypothesis, if proven to be true, will allow us to control mechanical properties of the composites by tailoring the SiC particles formed. It is also pointed out that the microstructure requires Si to be the dominant diffusing species and to diffuse through the reaction layer, while Nb and Conly have to undergo local rearrangement.

Jan 1, 1996

By Terry Gerritsen

Electrode control systems regulate power by physically positioning electrodes. Due to the size and weight of the electrodes, this is a slow process where power fluctuations of less than a few seconds are not fully corrected. Nickel laterite AC furnaces operating in high voltage, shielded arc mode typically incur frequent power variations of approximately +I- 20% around the power set point. To provide enhanced power control, Hatch has recently supplied, at commercial scale, a thyristor-switched reactance system called an SPLC. The SPLC incorporates predictive control software to operate furnaces at the maximum transformer rating by reducing the large power swings experienced without the SPLC. The resulting higher average power enables higher production, without increasing transformer or power plant capacity. A 60 MW production version of the SPLC has been commissioned on Falconbridge Dominicans's laterite nickel furnace, yielding excellent results with a 3 to I reduction in power fluctuations. Keywords: SPLC, AC Power Supply, Electric Furnace

Jan 1, 2004

By Richard D. Hagni

An enhanced Interest in pyrometallurgical dusts has recently emerged due to increased world-wide environmental concerns. Mineralogical study of dusts samples from lead sinter plants. lead smelters, and secondary steel mill electric arc furnaces has shown that they can be readily studied by reflected light microscopy. These dusts typically are composed of small particles sufficiently large that their mineralogical identification and characterization can be conducted under the reflecting light microscope. Scanning electron microscope-energy dispersive spectroscopic analysis (SEM-EDS) has been used to confirm optical identifications and chemical compositions. The sinter and blast furnace dusts at the Doe Run Smelter at Herculaneum, Missouri are commonly about 20-150 11m. They consist predominantly of galena, chalcopyrite, sinter. slag. coke. and particles. Dusts from remote sampling sites 112-1 mile from the lead smelter are composed of similar particles and abundant fine-grained particles, less than 10 um. of locally derived calcium-aluminum silicates. Electric arc furnace (EAF) dusts are mostly spherical and less than 10 11m. They consist predominantly of iron oxides (magnetite. franklinite. jacobsite and solid solutions of these spinels), zincite. and calcium-iron silicate glass, together with smaller amounts of hematite. sylvite. coke and metallic iron. Reflected light microscopy is rapid provides mineralogical data on individual grains within dust particles. and allows direct observations of textural intergrowths in pyrometallurgical dust particles.

Jan 1, 1991

By Daowu Yang, Zhuo Ren, Hui Liu

"In this paper, the photochemical catalysis degradation effect of photocatalyst obtained by charcoal-supported nano TiO2 (nano TiO2 / charcoal) on the formaldehyde in the air was studied. The influences of the nano-TiO2 loading and the photoreactor structure on the efficiency of photochemical catalysis degradation of formaldehyde was reviewed.The nano - TiO2 / bamboo charcoal adsorption of formaldehyde, as well as the influences of a certain amount of formaldehyde after adsorption on its photochemical catalysis effect were discussed. The sol preparation process of Ce-doped nano-TiO2 was described. Experimental results indicated that: the surface of bamboo Charcoal still has a strong formaldehyde adsorption capacity after Supported by Nano TiO2.After adsorbing formaldehyde, the photochemical catalysis degradation efficiency of formaldehyde of the catalyst at a steady state is basically the same with new prepared catalysts’. When the thickness of the catalyst layer of the multi-ladder-type structure photoreactor is 2mm, the interval is 20mm, the absorption efficiency of formaldehyde of Nano- TiO2 / bamboo charcoal is the best . Nano-TiO2 undoped Ce responded with no degradation of formaldehyde after 2 hours, while the degradation rate of formaldehyde of the Ce-doped nano- TiO2 reached 15% 2 hours late, and the formaldehyde decontamination of the equipment reached 94%.IntroductionEmerging out of home decoration in the distribution of formaldehyde, benzene, ammonia and other indoor pollutants have been proved to be very harmful to the human body. Photocatalysis can eliminate air pollutants, in particular, can effectively degrade the air volatile organic compounds, it is a new method of air purification developed in recent years. the biggest advantage of photochemical catalysis degradation is green, this method can be available at normal temperature and pressure to degrade formaldehyde and other organic matter into carbon dioxide and water without secondary pollution.Nano-TiO2 have become the most studied photocatalyst due to its stable, non-toxic harmless, superior photochemical catalysis properties [1]. Initially nano-TiO2 powder was used as a photocatalyst, but it’s difficult to recover and easy to wear and tear [2,3]. Later, the TiO2 was used in the form of film loaded on some carriers, such as glass beads [4]. As the photochemical catalysis reaction occurred on the catalyst surface, only the organic matter adsorbed on the catalyst surface can be degraded, so the catalyst was requested that must have a strong adsorption. Combined the adsorption properties of bamboo charcoal and the photochemical catalysis activity of nano-TiO2 together. Made the photocatalyst by loading the nano-TiO2 on bamboo charcoal to degrade organic matter in the air. Nano-TiO2 semiconductor photocatalyst has a strong catalytic oxidation due to the photo generated hole of the surface [5,6],and has a potential application. Some studies have shown that nano-TiO2 photocatalysis activity can be increased by doping certain metal ions [7,8].The aim of our work in this study was to use bamboo charcoal load Ce-doped nano-TiO2 photochemical catalysis oxidation to degrade formaldehyde,and design a multi-ladder structure photoreactor, also prove the availability of the device from the theoretical and experimental."

Jan 1, 2011

By Bin Du

In recent years, concurrent product design and process is gaining popularity and will become a norm of the industry of the future. Forging has been a critical manufacturing process for production of components with superior tensile strength, toughness and grain flow. This paper describes an expen system which is being developed for forging die design and forging process analysis in concurrent engineering environment. Rules and guidelines pertaining to forgeability are formulated and incorporated into the knowledge-base in building the system. The system is built using an object-oriented paradigm. The object-oriented approach and hierarchical rule structure paradigm are briefly discussed. Finite element analysis packages (ALPID-2D) were incorporated into the program to give the simulation result of the forging process. The system can automatically produce a competent design and recommend a set of processing parameters for a given product. The designer can modify the design according to the result of the simulation.

Jan 1, 1992

By J. Schmidl

In non-ferrous metallurgy the service life of refractory materials typically ranges from several weeks up to three years or more and is strongly dependent on operating conditions. To support our customers with the most viable refractory solution for their needs RHI Magnesita follows a structured approach of thermo-chemical calculations, experimental evaluation from lab scale up to industrial field tests and post-mortem analysis of used refractory materials. This paper will give an overview of the RHI Magnesita refractory selection process and the most recent developments of the experimental setup for the so called HF-IF test. This is a dynamic corrosion test that allows to determine fundamental properties of different refractory material types under process conditions subjected with respective customers process materials. The HF-IF experimental procedure is an excellent tool to simulate refractory wear in industrial processes, diminishing risks associated with plant trials and support decision making to choose the optimal refractory solution for the customer.

By Gerhard Bayer

X-ray and thermoanalytical studies were carried out on the formation and stability of Ca-, Mg-and Mn-tungstate, and of the corresponding minerals scheelite and wolframite. The tungstates were synthesized by different methods: precipitation from solution, solid state reactions, displacement reactions with solutions and in the solid state. The reactivity of natural scheelite and wolframite with different salt solutions and in mixtures with other minerals was investigated.

Jan 1, 1989

By Keiji Okumura, Jiayi Shan, Jian Yang, Masamichi Sano

"A new method of deoxidation and desulfurization of molten iron with magnesium vapor has been developed. An immersion tube, which was filled with pellets of the mixture of magnesia and carbon powders, was put into the molten iron. Magnesium vapor produced by carbothermic reduction of magnesia inside the tube was injected directly into the molten iron with argon carrier gas. The effects of temperature and carrier gas flow rate on deoxidation and desulfurization were investigated. A mathematical model of the reactions was developed. The rates of deoxidation and desulfurization were controlled by mass transfers of magnesium vapor in the gas-phase and oxygen and sulfur in the liquid-phase. This method may offer high efficiency for magnesium deoxidation and desulfurization of molten iron.IntroductionMagnesium is a strong refining agent in steel-making processes1 • At steelmaking temperatures, magnesium has a very low solubility in liquid iron, and a very high vapour pressure2 • Deoxidation and desulfurization with magnesium take place essentially through the interaction of magnesium vapor with oxygen and sulfur dissolved in molten iron, and magnesium can change chemical composition of nonmetallic inclusions3 • However, addition of magnesium to the steel bath is dangerous and does not give high efficiency in the refining process4 • Furthermore, as a refining agent, the price of magnesium is higher than aluminium and CaO fluxes. In the present study, a new method of the deoxidation and desulfurization of molten iron was developed using magnesium vapour in-situ produced by carbothermic reduction of magnesium oxide. Pellets made of mixture of magnesia and carbon powders were charged into an immersion tube, which was made of alumina or graphite. The magnesium vapor was injected directly into the melt. The effects of pellet mass, experimental temperature and carrier gas flow rate were studied on the refining rate. A mathematical model of the refining reaction was proposed on the basis of the experimental results."

Jan 1, 2000

By Deepu Philip, Pratik Agarwal, Ajay Kumar Shukla, Ishani Shukla, G Rajesh

Steel plants generally employ static BOF end point control models to arrive at a given temperature and chemistry at the end of blow. These end point models have now been supplemented with chaos control models to steer the blowing process in the right direction while the blow is in progress. Merely arriving at the correct end point temperature is however not adequate because in the subsequent stages as well the temperature variations can be large and unpredictable. The present paper deals with an integrated model to take into account the effect of all parameters affecting temperature and composition from tapping to the start of casting to minimize the use of LF or aluminum heating, and also minimize grade mixing. The application of lean operations strategy is explained in which the previous “Push System’ is changed to a “Pull System”, minimizing the use of ladle furnace or aluminum heating during steelmaking.

Jan 1, 2014