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By V. J. Ramirez, A. M. E. Noguez, M. J. Navarrete, B. G. Salas, N. T. Robert

"The close die forging stress in truncated conical cavities is evaluated with dimensional analysis. Five dimensionless groups are proposed from the process variables in order to simplify the forging stress determination. These groups are experimentally related and graphically expressed. This methodology can be used to predict the actual forging stress in industrial close die forgingThe use of the dimensionless groups allow to comprise more cases than the presented here, provided similar geometries and operational conditions.Introduction.Closed die forging is essentially a plastic deformation inside a two piece mold (forging die) with the inverted shape of the actual forging geometry. This plastic deformation will always be the result of a compressive stress. There are theoretical models which include complex calculations for the analytical determination of stresses (1, 2, 3, 4). Results of these calculations are approximate, requiring generally ulterior tests to obtain the true operational conditions(5).In this paper, it is presented a simplified approach to the actual compression stress needed in the forging. A well known tool in engineering: the Buckingham's Pi theorem in conjunction with dimensionless groups and a working piece scale model is used. Dimensional analysis will give the dimensionless terms needed to experiment with a selected scale model geometry to make the stress determination. The results presented demonstrate the reliability of this methodology."

Jan 1, 1997

By Takahiko Okura

Most non-ferrous raw materials are associated with sulphur. To extract the metals, the sulphur is recovered typically as sulphuric acid or liquid SOz, On the other hand, natural gas may contain over 20% of hydrogen sulphide (HzS) and a huge quantity of elemental sulphur is produced through oil and gas refining processes in the world. A large fraction of the sulphur mined from natural sources is eventually returned to the earth as fertilizers, by-products of desulphurisation and neutralisation processes, or as fugitives to the atmosphere. However, the supply and demand for sulphur are in imbalance. Such situation urges to develop a new smelting process without sulphuric acid production. This paper briefly reviews the global sulphur balance and the technologies for recovering elemental sulphur. The core of this paper is a proposal to convert SO2 gas to elemental sulphur by using organic materials. Some results of thermodynamic calculations and experiments are presented.

Jan 1, 2003

By Ernie M. Crist, Laurentiu Nastac, Frank Spadafora

"This paper describes the modeling techniques and the experimental and computer results for two casting processes that are under development and optimization. These processes are described as follows:1) Electromagnetic stirring (EMS) during casting of Ti-6Al-4V round ingots using the plasma arc cold hearth melting (PAM) process: The purpose of EMS is to establish a singlemelt PAM process capable of consistently producing as-cast ingots without helium porosity and also having no need for surface conditioning prior to secondary processing.. The modeling approach is based on the numerical solution of Maxwell's equations, fluid flow, and heat transfer equations, and mesoscopic modeling of the grain structure.2) Casting of Ti-6Al-4V slabs using the single-melt PAM process: The purpose of slab casting is to improve yield by eliminating an intermediate blooming step for converting round ingots to slabs. The modeling approach is based on the numerical solution of fluid flow and heat transfer equations. The effects of pouring and mold temperatures on the pool and temperature profiles were studied. Also, the torch effects (such as the torch standoff and its traversing path) on the pool and temperature profiles were investigated and the best-case scenario was used in the experiments. Evaluation results at RMI Titanium Company showed that the plates made from the slabs met the mechanical properties and microstructure requirements.Acknowledgment. This work was conducted by the National Center for Excellence in Metalworking Technology (NCEMT) operated by Concurrent Technologies Corporation (CTC) under contract No. N00014-00-C-0544 to the US. Navy as part of the US. Navy Manufacturing Technology Program. Dr. K. b. Yu from RMI and my colleagues from CTC are acknowledged for their comments on this work."

Jan 1, 2004

By A. Navarra

Within conventional copper and nickel-copper sulfide smelters, ladles of molten matte are fed into converters. These converters blast oxygen-enriched air into the matte, thereby eliminating iron and sulfur. The converting reactions are exothermic and, indeed, the converter heat balance is often a limiting consideration on the smelter throughput. If a portion of the matte were fed in solidified (granulated) form, this would support higher oxygen enrichment, and lower volumes of converter offgas, allowing higher throughput. This approach is not applied in conventional smelters, partly because of the copious amounts of water that must be evaporated in typical granulators, as in the Kennecott-Outotec process. The current paper recalls a waterless matte granulator that had been pioneered in the 1990’s, and is applicable to conventional smelters. A mathematical formulation is presented that can be used in the context of simulation-based optimization, to estimate the size and impact of waterless matte granulation.

By M. C. Flemings, S. B. Brown

"Metallurgy, as all of material science and engineering, rests on the intellectual foundations of processing-structure-property-performance relationships. Today it is widely recognized that processing has been too long neglected and presents exciting opportunities for exploitation. New processes, many of them already in the laboratory, will be exploited in the year 2000 and beyond, for near net shape forming and for achieving-new metallurgical structures and composite structures. Process modelling will alter the way we think about process and product design. Processes themselves will increasingly be automated and controlled by computers, altering the nature of the workplace and the tasks of the metallurgical engineer of the future. IntroductionInnovations in metal processing is hardly a new phenomenon, with the field thousands of years old. Nonetheless, the next few decades offer particularly important opportunities to improve our ability to process these materials. We appreciate today the variety of processing paths available to us, including vapor-, plasma- and electro-deposition, multiple phase and casting technologies, and non-equilibrium processes, and how these affect structure at the atomic level and at higher levels of aggregation. We understand the basic physical mechanisms involved far better than even before and have remarkable new abilities to predict, control, and simulate the kinetics underlying processes, and the processes themselves.The following sections describe these new opportunities in greater detail. First, we examine developments in the modelling of metal processing. We then consider some implications associated with process control and automation. Finally we present what we consider to be particularly promising metal processing technologies, and conclude with a few summary comments."

Jan 1, 1988

By Michaela Dina Stanescu, Emilia Visileanu, Eftalea Carpus

"The recovery and reintroduction into the economic circuit of the textile material resources must be considered as component parts of the strategies of harmonizing the relationships between the economic growth, consumption of natural resources and environmental protection of the existing socio-economic system.The waste recovery for ensuring a sustainable development is a major concern of all industrial researches. In the textile domain, the concern in this matter is becoming more evident. An important role in manufacturing textile products it has the notion of eco-design, which has grown considerably over the last twenty years with increasing awareness of environmental and social problems in the industry.Introduction“Humanity must learn from the global financial and economic crisis experience""- is the conclusion of the policy makers who should develop a strategy designed to reinvigorate the economy and make possible an"" intelligent, sustainable and favourable to inclusion” growth, by a better coordination of national and European policies.The new vision for social market economy is based on three priority areas: smart economic growth, the development of an economy based on knowledge and innovation; sustainable economic growth, the promotion of a competitive economy with low carbon emissions and an efficient use of resources, as well as an inclusive economic growth, the promotion of an economy with high degree labour employment, which would generate social cohesion. The recovery and reintroduction into the economic circuit of the textile material resources must be considered as component parts of the strategies of harmonizing the relationships between the economic growth, consumption of natural resources and environmental protection of the existing socio-economic system.The waste recovery for ensuring a sustainable development is a major concern of all industrial researches. In the textile domain, the concern in this matter is becoming more evident. It is obvious that at the origin of pollution there are the technological processes of textile processing with impact on air, water, soil, as well as the storage processes. In all phases of obtaining a product, a series of secondary products and textile wastes with impact on the environment occur. The product used becomes also a factor of environmental pollution, which in most cases fails to assimilate."

Jan 1, 2012

By Arthur S. Klein, Hugh R. Lowry

"The Levitation Casting Process is a new continuous casting method that uses an electromagnetic levitation field, instead of a mold, to support and contain a column of solidifying metal. By counteracting gravitational forces and hydrostatic pressure on the metal column, this process eliminates friction and adhesion at the interface between the solidifying metal and the cooled walls of the casting chamber. The process inherently provides high casting speeds, excellent dimensional control and smooth, continuous emergence of solidified product from the top of the casting chamber.Of major importance is that the electromagnetic field produces an intense stirring of the liquid metal both before and during solidification. As a result of this stirring, the cast product has a homogeneous, equiaxed, fine grain structure generally suitable for immediate drawing or other forming operations without the need for hot rolling or other expensive additional processing.This paper reviews the fundamentals of the Levitation Casting Process, results obtained in casting various pure metals and alloys, and the production sized system at Lowell, MA, that uses this process. IntroductionThe Levitation Casting process was specifically developed to meet several requirements including:• Economic at low casting rates• Usable with pure metals and alloys• High, uniform product quality suitable for fine wire drawing or cold rolling into flat strip and tape• Easy cast product shape and size changes• Process inherently stable and easily automatedIn meeting these criteria it was also desired to retain the advantages of General Electric's well known Dip Forming continuous casting process; namely the inherent ""fail-safe"" properties of upward casting, solidifying metal by means other than pressure contact with a cooled mold, and use of a sealed furnace, casting chamber and cooling tower, filled with a protective atmosphere, to prevent oxidation of the molten metal or cast product."

Jan 1, 1988

By V. P. Bystrov

Vanyukov process has been developed and investigated in Russia over the last 25 years. It has been established that various kind of material could be treated in Vanyukov process. The results of the pilot plant trials as well as industrial experience are presented in this paper.

Jan 1, 1993

By Yanhui Liu, Xuewei Lv, Pingsheng Lai, Chenguang Bai

The purpose of this paper is to study the effect of slag basicity on the Si content in stainless steel master alloys prepared by smelting reduction of Fe-Ni-Cr sinters. Theoretical analysis focusing on the gas, slag and alloy phases of the smelting reduction process at 1600°C was carried out by thermodynamic calculation software----FactSage, showing that the increase of CaO within the slag can result in the decrease of Si within the master alloy. Experiments were also carried out in vacuum melting furnace at 1600°C , and chemical analysis method was used to detect Si content in the alloys. When the MgO content is 9.00%, the experimental results were consistent with the calculated values. However, when the MgO content rises up to 14%, the content of Si in the alloy reaches the maximum when SiO2 equals to 22.81%.

Jan 1, 2016

By James J. Komadina, Robert R. Beebe

"Heap leaching of gold ores has enjoyed wide acceptance in the arid and semi-arid regions of the western U.S., Australia and South America. There are areas, however, where cold weather or excessive precipitation can limit the usefulness of heap leaching. Even in Nevada difficulties can be encountered which call for special operating procedures.The paper discusses the general climatological limitations and some of the techniques used to extend heap leaching into colder conditions. A case history of the Cripple Creek and Victor Gold Mining Company operation in Colorado examines 'valley-fill"" technology as an ideal cold-climate solution, where topographical conditions permit.AcknowledgementsThe authors gratefully acknowledge the management of Independence Mining Company for their permission to present this paper. The contributions of Golder Associates; Pikes Peak Mining Company Environmental Affairs Department staff, and the Colorado Department of Mines and Geology were all invaluable in successfully concluding this project.BackgroundWhen heap leaching of oxidized gold ores was introduced in the rnid-1970s it was aimed at large tonnages of low-grade material which could not, in general, be developed via conventional milling. Normally, the reasons for this were economic rather than technical: capital and operating costs for milling were simply too high. At first, grade was almost the only criterion, but deposits too small to justify milling were also potential targets for heap leaching.Renewed interest in gold was centered in the western United States and Australia, where exploration for milling-grade deposits had never really died. When heap leaching came along, it was in these areas that the first developments took place. Coincidentally, these same areas were favorable for heap leaching: climates were temperate for most of the year and competing land uses were limited. Even so, in the western United States in particular, winter temperatures were low enough to complicate operations. Precipitation was less a problem, although heavy snowfalls could periodically interfere as well."

Jan 1, 1997

By H. Walqui

Southern Peru Copper Corporation (SPCC) are currently modernizing the Ilo copper smelter. A single ISASMELT furnace will start smelting 1,200,000 tonnes per year of concentrate during the second half of 2006. The existing Peirce Smith converters are being upgraded for converting the matte to blister copper and a new acid plant and oxygen plant are being installed. Two new anode furnaces and a twin anode casting wheel have been installed in 2005 and commissioned in January 2006. The modernization project will ensure the smelter satisfies new environmental regulations due to come into force in January 2007. This paper summarises the background to the modernization project, describes the main design features of the new copper smelter and summarises progress on the smelter construction as of early 2006. This paper describes the genesis of the Ilo Smelter Modernization Project and describes in details the scope and current status of the project.

Jan 1, 2006

By R. K. F. Lam

Unacceptable levels of impurity were noted in high purity chromium melting. Analysis of recent melting data determined that oxygen content in chromium is the critical parameter. Thermodynamics studies identify zirconia to be the most stable oxide in the presence of liquid chromium, followed by alumina and silica. Iron oxide reacts readily with liquid Cr. A certain degree of chemical reaction between liquid chromium and oxides does occur, contamination by the crucible is therefore unavoidable. Equilibrium constants indicate that a chromium oxide addition decreases 'ceramic dissolution and reduces impurity contamination. Safe operating conditions with oxygen content between 1190 ppm and 2500 ppm were identified. Additions of chromium oxide (Cr2O3) of 161 grams and 264 grams to liquid chromium yielded acceptable levels of impurity, and oxygen content was respectively increased to 1624 ppm and 2 179 ppm. A new process of melting high purity chromium with chromium oxide addition for controlling the activity of Cr2O3 is recommended.

Jan 1, 1997

By Brent W. Madsen

The acid-ferric sulfate leaching of low-grade sulfide copper mine waste provides more than 10 percent of the U.S. supply of new copper, but recoveries and leaching rates are very low. In Federal Bureau of Mines research to improve the leaching process, experiments on 5- to 10-ton lots of mine-run ore were more revealing than bench-scale tests on fine ore. This report discusses the results obtained by leaching run-of-mine and minus 6-inch plus 112-inch samples of low-grade chalcocite-bearing mine waste. The samples were leached for 461 days and 61.6 and 37.7 percent of the copper was extracted from the minus 6-inch plus -112-inch and run-of- mine samples, respectively. A mixed kinetics model was applied successfully to the leaching of the sample with the fines removed where bulk solution transport was not rate controlling. The model, when applied to the run-of- mine ore, gave somewhat higher predicted copper extractions than experimentally determined. Subsequently, oxygen was introduced into the run-of- mine ore, leaching continued for an additional 312 days, and an additional 53.0 percent of the copper was extracted. Before the leaching experiment was dismantled and the residue sampled, the ore was treated with sulfur dioxide and its permeability was improved markedly. The results of each of these procedures are interpreted in relation to the attendant condition of the test.

Jan 1, 1976

By Henrlk Gripenberg

To solve the environmental and financial problems of the traditional Rotary Salt Furnace process, a new salt-free method for aluminum dross and scrap melting, ALUREC, has been developed by AGA and its partners, Hoogovens Aluminium and MAN GHH. AGA and Hoogovens Aluminium developed the main process concept and jointly carried out trials on pilot plant scale. Owing to excellent results" the partners decided to jointly erect a commercial scale test plant. The order for the design and erection of the furnace went to MAN GHH. The three companies designed the test plant and began operation in the spring of 1994. The results have been excellent and the process is expected to be a technical and commercial success.

Jan 1, 1995

By Alan DonaldsoN

Plasma Quench production of titanium is the thermal dissociation of titanium tetrachloride into gaseous titanium and chlorine followed by rapid quenching to prevent back reactions. Titanium tetrachloride dissociates into titanium and chlorine atoms at 5000 K. Expansion through a Delaval nozzle accelerates the gas to supersonic speed cooling it very rapidly. Cooling rates are as high as 7exp 1 0 Kelvins per second. Injected hydrogen reacts with condensed titanium particles to form titanium hydride and with the chlorine to form hydrogen chloride. We have produced titanium powder at 20 kglh in a continuous reactor. Costs are projected to be lower than the Kroll Process at large enough scale. Most of the cost reduction would result from elimination of magnesium as a reducing agent and much lower capital costs.

Jan 1, 2001

By Tapani Järvinen

Non-ferrous metals and metals in general are considered as being non-renewable natural resources. Metals are needed because of their excellent and irreplaceable properties. The consumption of metals, with the exception of carbon steel, is steadily growing by 1-3 % annually, and that of stainless steel as much as 3-6 %. This is a general trend, which is periodically disturbed by cyclical variations. In recent years so-called "New Economy" has become prominent in the public media and the market value of the traditional industry has been well below its real value and importance. Nevertheless, the modem society requires metals today and also in the future, and the companies using the most modern technology in a responsible way and innovative solutions not only in technology, but also in everything they do will survive. This paper describes the role of Europe as a producer of primary base metals and as a supplier of technologies in the base metals industry. It concentrates on the development and commercialization of technologies and project implementation in the metallurgical industry. As one example ofa European approach to these matters the paper presents Outokumpu's response to the future challenges in the base metals industry. Outokumpu Oyj is one of the leading metals and technology companies in the world of stainless steel, copper, zinc, and sales of technology in metals and minerals businesses. Outokumpu applies its knowledge of metals and processing to generate value for its customers and shareholder. Everything we do, we do in an economically, environmentally and socially responsible way.

Jan 1, 2003

By Kathryn C. Sole

A novel solvent-extraction process for the refining of gold was recently commercialised, with the commissioning in May 1997 of a 24 t a-' refinery at Harmony Gold Mine in Virginia, South Africa. The MinataurTM Process (Mintek Alternative Technology for Au Refining) uses solvent-extraction technology to produce gold of 99.99% purity from the cathode sludge arising from a conventional carbon-in-pulp / electrowinning circuit. Implementation of this process introduces significant cost benefits compared with the conventional dore smelting / toll-refining route previously followed. This paper outlines the process, presents selected operating results obtained during the first few months of operation, and provides some details of the associated techno-economic advantages.

Jan 1, 1998

By Ki Joo Sim, Sung Beom An, Joonho Lee, Minsoo Shin

Valorization of the electrical arc furnace oxidizing slag by coke was carried out by the reduction of iron oxide in the slag. Since the reduction of iron oxide by solid carbon is an endothermic reaction, supply of heat energy is required. In addition, slag has a low thermal conductivity; traditional fuel injection is not suitable for this reaction. Microwave can be used to supply heat energy to the system. Commercial oxidizing slag was reduced by coke under the microwave irradiation (1.7 kW, 2.45 GHz). The maximum recovery ratio of iron was 87%. In addition, slag composition modification was attempted to use the remaining slag for a mixture in cement clinker. Free-CaO in the slag was successfully suppressed, and the use of the remaining slag as a potential mixture was confirmed.

Jan 1, 2014

By Tadashi Aiura, Yasuhiro Miura

"A small amount(0.2mass%) of Scandium(Sc) was added to the 7.NOl and 5083 Al alloys as a refiner and stabilizer of microstructure, and the resulting microstructures were discussed in comparison with the effects of the conventional additives. The followings are summarized: 1) in the as-solidified structure, a ·decreased tendency of constitutional supercooling and increased solubility of Mg were recognized for the Sc-added 5083 alloy. Sc is a -better microstructure refiner for the 7N01 alloy than Zr, in a sense that it does not suppress the favorable effect of· coexisting Ti. 2) Sc effectively suppresses recrystallization both in the 5083 and 7N01 alloys. 3) The rod like primary Al3Sc crystals formed during solidification, as well as the fine dispersion of Al3Sc precipitates formed by subsequent heat treatment, can act as a strong recrystallization suppresser. IntroductionThe 7N01 and 5083 alloys are the most popular industrial Al alloys and they are widely' used for various structures because of their superior properties. Fine macro and micro structures of the materials are required for obtaining acceptable sec resistance,consistent appearance of anodized surface and good weldability, as well as good mechanical properties. In order to produce fine grain structures, transition metals, such as Cr, Zr, and Mn, have been conventionally added.It has been reported that Sc is an efficient refiner [l, 2] and can be an alternative for the conventional and also suppresses recrystallization in Al alloys [3,4]. Scandium is the lightest transition element and forms an equilibrium intermetallic phase. The equilibrium phase, Ll2-Al3Sc, is coherent with the matrix, and of _spherical shape. A fine dispersion of the spherical precipitates is obtained by quenching and aging after solutionizing annealing. The authors have already reported a part of the experimental results on the effect of Sc on the as homogenized microstructure of the 5083 alloy [5]. In the present study, the effects of Sc on the macro and micro structures of the industrial high strength Al alloys(7N01 and 5083) for extrusion are investigated, and the superior role of Sc as a grain refiner is shown"

Jan 1, 2000

By James C. Barker

Recent investigations of a 55-km long trend of intrusive complexes on southern Prince of Wales Island have identified significant resources of Nb, Y, REE. U, Zr, and a host of potential by-product metals. The northwesterly trend comprises multi-phased sodic alkaline and peralkaline diorite, monzonite, syenite, and riebeckite granite. There are at least three significant deposit types recognized, two of which, 1) pegmatite dikes/vein-dikes that zone laterally from the intrusions and 2) concentrically zoned pegmatites, contain most of the lithophile metals. A third, epigenetic replacement-type mineralization, contains much of the U resource. Other deposit types with minor or unknown resource potential include diatremes, carbonatite, and placers. This report summarizes the deposit evaluations, characterizes the mineralization, and estimates the resources. To date a total of 40.7 million tons of mineralized material is estimated as indicated or inferred. Most of the Y203 plus REO is at a grade exceeding 0.5% and half of the Nb20S exceeds 0.125%. Tonnage estimates would likely be substantially lncreased with additional exploration. Mineralogy is generally fine-grained and complex, and consists of more than a dozen principal REE-Y-Nb-U-Th-Zr phases, the sum of which may compose up to half of the rock. Approximately half of the REE-Y content comprises the heavy yttrium subgroup which is uncommon compared to deposits elsewhere. Although the Alaskan deposits are likely subeconomic at today's metal prices and consumption levels. recent technological advances suggest future demand may increase.

Jan 1, 1988