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By Jozef Zmik, Sergey Dobatkin, Martin Fujda, George Raab, Libor Kraus

"The present work, likewise, deals with grain refinement of medium carbon steel AISI 1045 having different initial microstructure resulting from thermal and/or thermomechanical treatment (TM) applied prior severe plastic deformation. In case of TM treated steel, structure refinement was conducted in two steps. Preliminary structure refinement has been achieved due to multistep open die forging process which provided total strain Eef ~ 3. Uniform and fine recrystallized ferrite structure with grain size of the order of 2-5 µm and with nest-like pearlite colonies was obtained. The further grain refinement of steel samples having different initial structure was accomplished during warm Equal Channel Angular Pressing (ECAP) at 400°C. The microstructure development was analyzed in dependence of effective strain introduced ( Eef ~ 2.5 - 4). Employment of this processing route resulted in extensive deformation of ferrite grains where mixture of subgrains and ultrafine grain was found regardless the preliminary treatment of steel. As straining increases the dynamic polygonization and recrystallization became active to form mixture of polygonized subgrains and submicrocrystalline grains having high angle boundaries. The intensive straining and moderate ECAP temperature caused the partial cementite lamellae fragmentation and spheroidization as straining increased. The lamellae cementite spheroidization was more extensive in TM treated steel samples. The deformation behavior of for both steel structural state confirm the strength increase; however the work hardening behavior was modified with respect to initial structure of steel prior SPD processing.IntroductionIn the last years, ultrafine grained materials have attracted considerable research interest because they tend to possess high strength without sacrificing toughness and ductility. Microstructural refinement of steel is usually achieved by alloying and/or by thermomechanical treatment process, which modifies phase transformation. Recently, advancement of severe plastic deformation (SPD) techniques provides another efficient access for grain refinement of metals and alloys. The fabrication of bulk materials with ultrafine grain sizes has attracted a great deal of attention over the past two decades because of the materials' enhanced properties [ 1, 2]. In last decade a worldwide effort in manufacturing process to obtain ultrafine grain structures in steels is persisting."

Jan 1, 2011

By Bruce R. Conard

Consideration of environmental and human health issues in metallurgy is growing rapidly. While not all metallurgists need to have detailed expertise in environmental and health questions, they should be aware of the challenges the metals industry faces, be able to interact with colleagues in other sciences and contribute to sound metal resource management. Hydrometallurgists occupy a unique position among metallurgists because of their knowledge of the behaviour of metals in aqueous systems, which are of fundamental importance in understanding environmental chemistry and human toxicology. As a result, hydrometallurgists should more frequently and passionately lend their expertise in assessing environmental and health risks of metals and in helping to develop effective global guidelines, regulations and process and product stewardship strategies, thereby enabling metals to continue their beneficial service to society.

Jan 1, 2003

By Reinhold G. Schulze

Thiourea is being applied as an industrial leaching agent for gold and silver only in a few cases. A GIP technique was developed which eliminates most of the obstacles against its use. Omission of an acid treatment and mild conditions for precious metals stripping from the loaded carbon simplifies process conditions in comparison to cyanide CIP technique. Examples are given.

Jan 1, 1989

By Alejandro R. Alonso, Lizet Alvarado, Gretchen T. Lapidus

"Cobalt and lithium recovery from spent Li-ion secondary batteries has been increasingly studied in recent years due to the high value of both metals and the low proven reserves for lithium. The standard method employed until now has been the deactivation and crushing of the batteries, followed by leaching of the L1C0O2 spinel from the battery cathode using acid solutions, such as 1.5 to 2.0 M HC1 or H2SO4, in a temperature range from 120°C to 250°C. Once leached, the cobalt is separated by electrodeposition and the lithium by precipitation, using large amounts of carbonate to bring the solution to alkaline pH values. In the present work, citric-thiosulfate solutions are used for the spinel leach at room temperature, favoring a reductive environment at room temperature, which stabilizes the cobalt(II) as cobalt citrate and lithium(I) at pH 5, and recovers approximately 99% of both metals.IntroductionThe Li-ion batteries industry has become an important economic sector in recent years. This type of battery is the most promising system for energy storage, because of its high efficiency in charge-discharge cycles, and its adaptability to many configurations. The demand will probably increase because of the need for mobile energy sources in many types of devices ranging from cell phones, tablets, and laptops to medical, navigation and sophisticated communication equipment and even in automobiles.One major problem related to the use of these batteries is the method employed for recycling the components, mostly cobalt and lithium. Currently, there are two processes employed on an industrial scale: the Sony/Sumimoto process, used since 1990 [1] and the Toxco Process [2]. In the first case, incineration is used to open the batteries and at same time volatilize the organic solvents. After that, the metals (copper, iron and aluminum) are physically separated. The cobalt and lithium are recovered as oxides and then thermally treated in order to recycle them for new batteries manufacture."

Jan 1, 2012

By Chikabumi Yamauchi, Mitsuru Tanahashi, Jutaro Miura, Takaharu Iwadachi, Toshiharu Fujisawa

"Tue oxidation behavior of molten Cu-Be alloys was investigated by exposing· the molten Cu-Be alloys to various Ar-O2 atmospheres to control the oxygen partial pressure, PO2 = 10 ~105 Pa at 1423 K. The following results were obtained:• The oxygen · partial pressure in gas phase affects the morphology of the oxide formed on the surface of the alloy and · the oxidation rate of beryllium.• At lower oxygen partial pressure, a molten Cu-Be alloy is covered with a homogeneous and compact internal layer of BeO. Thus, the beryllium oxidation rate can be minimized.• By adding a small amount of calcium or zirconium into the molten Cu-0.5 mass% Be alloy, a protective BeO layer is formed even at higher oxygen partial pressure. Thus, the beryllium oxidation rate can be reduced.IntroductionCopper-beryllium (Cu-Be) alloys are well recognized for their unique properties, such as high electrical conductivity, high strength, high fatigue strength, excellent properties at elevated temperatures, good formability and good corrosion resistance. .This extraordinary collection of properties are the reasons why Cu-Be alloys are expected to be ""Key-materials"", which are necessary to further advance science and technology and to be applied in.various fields such as electronic devices, machine parts, repeater housings of undersea optical fiber communication cables, etc.However, a large amount of beryllium is oxidized to BeO in melting stage of the current Cu-Be alloy production process, because beryllium is a highly reactive element. This is one of the ·main factors that negatively affect the production yield and th_e product quality."

Jan 1, 2000

By Shabnam Sabah, Geoffrey Brooks

In oxygen steelmaking, splashing and droplet formation play a key role in the kinetics of the process. Though splashing has been studied by previous investigators, there is only limited understanding of how different cavity modes affect splashing. Therefore, a cold model study (at various lance heights and gas flow rates) has been carried out focusing on the issue of cavity modes and how it affects splashing phenomenon. Analysis using Fast Fourier Transform (FFT) was carried out on cavity oscillation that showed that frequency and amplitude of oscillation was highest in penetrating mode. Measurements of splashing over a range of conditions showed splashing greatly reduced when cavities went from splashing to penetrating mode. The results were validated and compared with plant data and previous model investigations.

Jan 1, 2014

By L. M. Bianchi

"Oxide, nitride and other compound coatings often do not have adequate properties for newer applications when produced using very high deposition rates and simple evaporation techniques. Solar control, abrasion resistance, low reflectance and barrier effective engineered coatings require exacting properties. Such properties can be obtained by adapting the activated reactive evaporation (ARE) technology to Web production processes. Adaptions of the HAD and MAD processes will be described along with data on the high deposition rates obtained. These fast production capabilities were developed in order to make the processes economically competitive.IntroductionThe Physical Vapor Deposition technique (PVD) has been used to coat steel strip for over 20 years. (1) However, its use as a production process has been very limited because of the high cost of the PVD coating process and because, in some instances, the properties of the coating were not good enough to meet the customers requirements. Nevertheless, the PVD process has found wide application in the airplane engine and electronic component markets. These production processes have stimulated further development and advances in the technology.In 1971, Profession R. F. Bunshah developed the Activated Reactive Evaporation (ARE) process which was then used to produce hard coatings such as carbides, nitrides, oxides and other refractory compounds. (2) The process from a fundamental viewpoint -produces a coating on the substrate via the evaporation of metal in the presence of a low pressure (typically around 1 millitorr) of reactive gas, with a plasma created in the space between the metal source and the substrate.The plasma may be created by many means but its function is two-fold. First, it activates the reaction between the metal vapors and the reactive gas atoms/molecules resulting in the formation of a compound that deposits on the substrate. Second, because the plasma is in contact with the substrate, it results in a negative bias on the substrate and produces bombardment of the growing film with ions and energetic neutrals from the plasma. This bombardment causes many significant changes in the microstructure, properties and appearance of the coating.Recently another new technology Pulsed Magnetron Systems (PMS) has been introduced into PVD. This new technology has been pioneered in production scale equipment by Dr. S. Schiller (3) and associates. The use of a pulsed power supply on the magnetron prevents the problem of the anode being coated with a insulating layer which will then lead to micro and macro arcing producing defects in the coating."

Jan 1, 1998

By Vladyslav P. Yakubovsky, Boris I. Bondarenko, Valentin A. Noskov, Vladyslav M. Sokolov

"Each of Ukrainian producers of ferronickel, stainless steel and synthetic diamonds has the same basic problem with recycling their fine Ni-containing secondary materials. The conditions for generation of them along with the correspondent properties were investigated in details. The new approaches for their recycling have been proposed. They are based on application of some pyrometallurgical processes that are used in Ukraine. The proper equipment is also available. It has been shown that the dust from laterite calcining process of ferronickel production should be efficiently recycled by sintering. The stainless steel dust should be smelted after briquetting as a charge addition to the Ni-containing discarded batteries in the elaborated furnace. The sludge after synthetic diamonds production should be pelletized and processed by liquid cast iron with application of induction magnetodynamic forces in the specific furnace.IntroductionThe object of the investigation is recycling the Ni-containing secondary fines in a form of dust and sludge. There are several generators of the fines in Ukraine. Namely they are Pobuzhye Integrated Ferronickel Mill; Electrometallurgical Works “Dneprospetsstal” with stainless steel plant as well as Poltava Diamond Plant that produces synthetic hard materials. Their businesses are the largest in the Commonwealth of Independent States (CIS). However the status of handling with the fines is not perfect since the applied recycling technologies are low efficient. The landfilling option is often adopted for them. At the same in Ukraine there are some nontraditional pyrometallurgical recycling technologies and equipment that should be tried for application in smelting these secondary materials.Recycling the sludge of synthetic diamonds productionThe sludge of “Poltava diamond plant” from production of synthetic hard materials has a following chemical composition, %: iron oxide – 29.7; chromium oxide – 18.97; nickel – 4.27; manganese oxide – 15.2; sulphate – 3.85; natrium – 14.9. The content of moisture is 70-80%. The moisture quite quickly evaporates while keeping sludge out of doors. Sludge returns into the weak agglomerates. The sizing of the dried sludge particles presents the figures from 400 to 1000 µm. The moisture was extracted by sludge pressing. The content of the basic compounds of the moisture is, g/dm3: chromium oxide – 1.6; nickel – 0.001; manganese oxide – 0.002; lead – 0.005; sulphate – 13.6; natrium – 17.0."

Jan 1, 2008

By Patricio Barrios

This paper discusses the revamp and expansion of Atlantic Copper's (formerly Rio Tinto Metal) copper smelter located at Huelva, Spain. The plant was expanded from 150,000 to 270,000 tpy new copper in anodes, and from 133,000 to 215,000 tpy cathodes. Lurgi successfully executed this contract on a lump-sum, turnkey basis in just 19 months. The Lurgi on-site task force performed this work in close cooperation with Atlantic Copper's personnel, with a minimum of disruption in the plant's ongoing operation. The contractual performance parameters were achieved to the client's satisfaction shortly after the mechanical completion of the respective plant sections.

Jan 1, 1998

By Joseph Sofra

It has become increasingly evident that sustainable metals production in the 21st century requires producers to balance the needs of cost effective, high value production with that of responsible plant operation. This is becoming more difficult as lower grade and more complex feed materials, including recycled scrap and residues, are being processed to reduce production costs and decrease exposure to primary metal market fluctuations. One particular facet of the metals industry facing these challenges in the 21st century are copper producers, The recent steady decline in the copper price has seen the industry cut expenditure, tighten control on income streams and focus on high returns on capital investment. For these reasons copper producers are looking towards flexible technologies that can deliver high value products, with minimal environmental impact at low capital and low sustainable operating costs. Ausmelt's Top Submerged Lancing (TSL) technology for copper production is a low cost, proven technology for the processing of both primary and secondary copper materials. Both the smelting and converting operations introduce significant advantages in environmental performance, improved process efficiencies and high rates of metal recovery, Ausmelt has made significant gains in the past 4 years in establishing a strong market position for its copper technology, New installations in China, South Africa and India as well as existing operations in Zimbabwe and China have demonstrated its effectiveness. This paper reviews the application of Ausmelt Technology for both smelting and converting of primary and secondary sources, It discusses Ausmelt's design and implementation philosophy, and how this philosophy meshes with the needs of the end user.

Jan 1, 2003

By Germán Richter a

To comply with the chilean air quality regulation requirements, the Hernan Videla Lira Smelter which is a custom smelter having to cope with a wide variety of concentrates, has developed a two-step modernization plan. The main steps are: - A second acid plant of 80,000 Nm3/hr to be operating at the end of 1996. This will increase the sulphur capture from 43% to 701/o in association with the replacement of the Hoboken converter by a second PS-converter to reduce the operation problems resulting from the treating of high garde matte. - Oxygen enrichment, is going to be incorporated in 1998 in the Teniente Converter and PS-converters in association with tuyere injection of dry concentrates, increasing the sulphur capture to 90 - 93% of sulphur inputs. By this program, sulphur emissions will be decreased from 40,000 tpy today to less than 8,000 tpy and in this way to carry out the environmental regulations.

Jan 1, 1996

By Aly M. Abdel-Rehim

The present work deals with a study of the mechanical activation of processing of Egyptian monazite by its simultaneous ball-milling and pressure leaching in order to improve the recovery of thorium and lanthanides from monazite. Experiments of simultaneous ball-milling and alkaline leaching of monazite contrary to autoclave leaching were carried out in stainless steel ball-mills of cylindrical shape under different conditions of temperature, pressure, time and alkali amount and strength. The ball-mills were heated and mechanically rotated in an electric furnace by means of roll mechanism. The effective rotation speed was fixed at 130 rpm in all tests. The charge of steel balls of different diameters was equivalent to 45% of the total mill volume. Monazite was charged in ball-mill without preliminary grinding. It is found that high rate of monazite leaching by ball-milling leaching method is achieved at lower temperature, shorter time and lower expense of alkali than in autoclaves. The results obtained show that complete recovery of thorium and lanthanides from monazite (99.8%) by simultaneous ball milling and alkaline leaching is attained at 140°C within 2 h. It is concluded that processing of monazite by its simultaneous ball-milling and leaching is mechanically activated and accelerated as a result of grinding action of steel balls that caused the continuous removal of the hydroxide product from reacting particle surfaces. This leads to the exposing of fresh and activated monazite particles surfaces to alkali leach solution and consequently the acceleration of the reaction of monazite processing.

Jan 1, 2006

By R. W. Lee

The first prototype plant using the Imperial Smelting Process commenced operation in 1950. It is timely therefore to review the developments that have occurred with the process over the past half-century. A major advantage claimed initially for the process was its ability simultaneously to recover zinc and lead from bulk concentrates. This has remained a fundamental advantage, but it has been extended by the increasing treatment of secondary materials containing zinc and lead. This has been facilitated by the development of hot briquetting and tuyere injection. These techniques and their impact on the technology of the operation will be described. The other major advantage claimed for the process was its potential to achieve new levels of productivity in the pyrometallurgical smelting of zinc. This has been realised with operating furnaces producing up to 400 t/d of zinc. The technical developments that have enabled this scale of operation will be reviewed.

Jan 1, 2000

By Jinxing Ji

The thiosulfate lixiviant system for leaching of gold has been under extensive investigation for nearly two decades and consists of ammonium thiosulfate, copper and ammonia. There are several challenges with this system. The occurrence of ammonia must be taken into account from a health and hygiene aspect in the workplace, and also from an environmental perspective with significant levels of ammonia and copper in the tailings. Copper accelerates the leaching rate but causes excessive thiosulfate degradation. A new lixiviant system that has been investigated consists only of sodium thiosulfate without copper and ammonia. Gold leaching is carried out in an enclosed reactor with slightly elevated oxygen overpressure and temperature. Extensive leaching experiments were carried out to minimize thiosulfate degradation and polythionate formation while maximizing the gold extraction. For the preg-robbing carbonaceous ore sample tested, gold leaching was essentially complete within six hours and the thiosulfate consumption was lower than in the typical ammoniacal thiosulfate system. The gold thiosulfate complex in the pregnant leach solution was found to be quite stable under ambient conditions. This new leaching system has the advantages of being more environmentally friendly, has a shorter residence time, lower thiosulfate consumption, lower oxygen consumption, and is easier to control.

Jan 1, 2003

By Pan Cao

The process of reduction roasting of nickel laterite with rotary hearth furnace combined with magnetic separation becomes a very potential way to prepare ferronickel alloy, especially for the low grade nickel laterite ore. In order to realize this new process, the effect of roasting temperature, time and additive on the reduction degree were investigated in the laboratory experimental. The results indicated that the recovery rate of Ni increased with the roasting temperature increasing to 1500°. Most of nickel and a spot of iron are selectively reduced with adding 25.19% SiO2, 6.42% coal, and roasting for 60min at 1500℃. Then conventional magnetic separation was carried out. The content of Ni and Fe are 7.50% and 59.08% in ferro-nickel nugget prepared by this method. And the recovery rate of Ni is 90.91%, which indicates that a high recovery of ferro-nickel from nickel laterite ore is achieved indeed.

Jan 1, 2014

By Fumiatsu Sato

In recent years, an increasing number of urban soil contamination cases have been found during redevelopment of former factory sites. Hydroclassification technique, separating heavily contaminated fine soil particles from contaminated sites, is one of the economical remediation techniques for contaminated soil by heavy metals, but the separated fine soil particles are generally landfilled because of the difficulty in removing strongly adsorbed heavy metals on them. In the previous study, the authors have investigated the mechanism and the optimum condition of chlorination-volatilization technique to eliminate heavy metals from inorganic waste and found it was needed to heat up around 1273K. In this paper, a new remediation technique for lead contaminated fine soil particles is proposed. This technique is composed of chlorination and subsequent warm water extraction. In the chlorination step, water-insoluble lead complex is chlorinated to be water-soluble lead chloride without volatilization, by heating the soils with MgCl2-CaCl2-KCl salt mixture at relatively low temperature. By subsequent warm water extraction, lead chloride is leached out. Effects of chlorination conditions, such as time, temperature, composition of the salt and added salt ratio, on lead behavior were investigated. It was proved that lead concentration could be reduced below Japanese environmental standard.

Jan 1, 2006

By John P. Hager

One possible approach for the recovery of mercury from acid plant blow-down sludge in smelters is the use of a vacuum retort reactor for the vaporization of the mercury with subsequent collection of metallic mercury in an attached condenser. An experimental study was undertaken to investigate the vaporization of mercury when present as a compound in the Hg-S-O and Hg-Se systems. A transpiration reactor was modified to operate under reduced pressure and with a continuous flow of inert sweep gas. A water-cooled cold finger was inserted into the exit end of the reactor to provide for the rapid quenching of the exit gases and the collection of the mercury. Rates of vaporization were measured at several temperatures for each compound and were generally found to be constant at a given temperature and reactor pressure. The results were used to determine the minimum operating temperature for 100% vaporization of the compound in 60 minutes. For Hg2SO4, HgSO4, and HgSO/2HgO the required temperatures. for a reactor pressure of 50 Torr. were determined to be 634°, 622°. and 603°C. respectively. For HgO, HgSe, and HgS the required temperatures were 557°. 451°. And 382°C. respectively. For HgS the rate of vaporization was also measured at a reactor pressure of 1 00 Torr. The rate of vaporization was found to be slower resulting in an increased vaporization temperature of 423°C. It was also determined that the mercury vapor present in the exit gas stream can back-react with the other gas species to a significant extent and can result in very little condensed metallic mercury. For the vaporization of both HgS and HgSe. the mercury vapor was found to have back-reacted to the extent that virtually none of the vaporized mercury was collected in metallic form. For the vaporization of Hg2S04? HgS04, and HgSO4*2HgO the amount of metallic mercury recovered varied from approximately 50% for HgS04*2HgO to approximately 10% for Hg2S04 and HgS04. Only for HgO was the recovered mercury in primarily elemental form. The application of the results to the operation of a vacuum retort and condenser system is discussed.

Jan 1, 2001

By Terry C. Cheng

The Akita Hematite Process is currently the only hydrometallurgical iron removal process producing saleable iron by-products in the zinc industry. In this study, McGill University and Akita Zinc Co. have worked together into elucidating the basic precipitation chemistry of the process from the standpoints of hematite product quality and prevailing precipitation kinetics. This work determined that hematite is produced under the applied conditions (T = 195?200oC,PO2 = 103?414 kPa) directly without prior formation of basic ferric sulphate and transformation of the latter to hematite as thought originally. The rate-limiting step responsible for the long retention time (~180 min) was found to be either the re-dissolution of ferrous sulphate according to the batch reactor studies, or the slow hydrolysis of the remaining ferric sulphate according to the continuous reactor studies. Another interesting contrast between the batch and continuous reactor data was the degree of sulphur contamination (1.5 vs. 3.8%, respectively) and the specific surface area of the product (10 vs. 30 m2/g, respectively). These differences in addition to the co-precipitation of SO4-containing phases such as jarosites, alunite, and anhydrite were attributed to the significantly higher supersaturation level prevailing in the industrial continuous autoclaves that yields highly aggregated sub-micron hematite crystallites contaminated with chemisorbed sulphate ions.

Jan 1, 2003

By N. S. Narayanan

Monazite, one of the major sources of rare earths, is normally opened by digestion with hot concentrated caustic soda solution. Caustic digestion dissolves phosphate and leaves a hydrated mixed metal oxides cake containing thorium, uranium and rare earths. By leaching this cake with hydrochloric acid at pH 3.0 to 3.2 bulk of the rare earths are preferentially removed and separated. The slurry left after removal of major portion of rare earths contains all the thorium and uranium present In the feed monazite. In addition this slurry also contains substantial quantities of rare earths. Solvent extraction tests were carried out to develop a process to separate rare earths, thorium and uranium present in the mixed chloride solution obtained by dissolving the above slurry in hydrochloric acid. Based on these tests a solvent extraction flow sheet was developed with di-2-ethyl hexyl phosphonic acid mono 2-ethyl hexyl ester as the extractant. The details of experimental work and results obtained are discussed and a flow sheet for processing monazite Incorporating the new process is suggested.

Jan 1, 1997

By Linli Wu, Guangchun Yao

"The influence of deformation on the properties of short-carbon-fiber reinforced 2024 alloy matrix composites was investigated in this study. It was found that the distribution of carbon fibers changed from the random state before deformation to the ordered state that carbon fibers arranged along the direction of rolling and extruding after deformation. Under the temperature range in control, the increase of rolling and extruding temperature would benefit to improve strength and elongation of composites, but was not conductive to improve the hardness of composites. With the increment of total deformation, all the strength and the hardness of composites became greater, nevertheless the elongation decreased. After being rolled and extruded, the strength and the hardness of composites were all bigger than those of composites before being rolled and extruded; moreover, the strength of extruded 2024 alloy matrix composites was higher than that of rolled 2024 alloy matrix composites under the same heat treatment conditions.IntroductionCarbon fibers have been reckoned as very important reinforcements due to the high specific strength, specific modulus, high thermal and electric conductivity, low expansion coefficient and good self-lubricant properties [1-4]. Light metal composites reinforced with carbon fibers, such as carbon fibers in an aluminum matrix, are widely used and studied. Some studies have concentrated on the interfacial characteristic of CF/Al composites in order to search for the way of improving the bonding between carbon fibers and the matrix alloy [5-8], and on the influence of the carbon fiber percent composition in the composites [9-11]. Some researchers began to take interest in the deforming characteristic and failure behavior of carbon fiber reinforced metal matrix composites [12-16]. However, the same with other metal materials, most of CF/AI composites were prepared by some single processes, such as powder metallurgy, extrusion casting and vacuum press infiltration, which caused that the composites products could not be manufactured directly. In order to cover the shortage of the mentioned above processes and get composites products with perfect mechanical properties and dimensional accuracy, the composites should be reworked by rolling, extruding or forging process. Compared with research about manufacturing process, the correlative investigation on the reworking of CF/Al composites was much less evidently, which restricted the application and the further development of CF/Al composites."

Jan 1, 2012