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By Eun Duck Park

The gold catalyst supported on iron oxide was prepared from gold dissolved in aqua regia by a deposition-precipitation method and applied to CO oxidation in the absence and presence of hydrogen. Some characterization methods such as X-ray diffraction (XRD), nitrogen adsorption, transmission electron microscopy (TEM), temperature programmed reduction (TPR), temperature programmed oxidation (TPO), and the pulsed CO chemisorption with temperature programmed desorption (TPD) were conducted to explain different catalytic activities of Au/Fe2O3 catalyst pretreated at different conditions. The particle size of gold was about 10 nm for Au/Fe2O3 calcined in air at 373 and 573 K. For complete CO oxidation, the decreasing CO conversion with a reaction time was observed at low temperatures but its initial catalytic activity can be restored by a heat treatment at high temperatures. This catalyst was quite active for the selective CO oxidation in the presence of hydrogen especially at low temperatures. In the presence of hydrogen, the deactivation was significantly diminished.

Jan 1, 2006

By Shunsuke Yagi

A surface alloying technique was investigated using alternating pulsed electrolysis in an aqueous solution containing a single metal component for the formation of an Fe-Cr layer on an iron substrate. In the process, the iron substrate was dissolved during each anodic polarization of the pulsed electrolysis, providing iron ions in the vicinity of the substrate, while the Fe-Cr alloy was electrodeposited during subsequent cathodic polarizations. A bright, flat, and crack-free Fe-Cr layer with a composition gradient was obtained using a solution containing a trivalent chromium component and a complex forming agent together with some supporting or buffering salts.

Jan 1, 2006

By Jackson Jenkins

The second survey of world copper SXEW plants has been completed. Solvent extraction and electrowinning data published in 1996 has been updated and leach data from seventeen plants is now included. The following pages list the results of the thirty- two plants that responded to the survey. Selected information is summarized in graphical form.

Jan 1, 1999

By Sun-Hee Cheong

This study sought to produce L(+)-calcium lactate using precipitated calcium carbonate as a starter culture composite of lactic acid bacteria in lactic acid fermentation. Specifically, precipitated calcium carbonate was synthesized by reacting calcium hydroxide with sodium carbonate in the previous study by the authors. Synthetic precipitated calcium carbonate was then used as the calcium source of lactic acid bacteria during the fermentation process. In general, precipitated calcium carbonate has low absorption rate in the human body. On the other hand, calcium lactate has high absorption rate; it is commonly used in food and drug industries as calcium additives in various foods such as cookies, beverages, bread, sauces, powdered milk, and fruit juice. Calcium lactate has two racemates, e.g., L(+)-lactate and D(-)-lactate. In particular, L(+)-lactate is known to be more soluble than D(-)-lactate and generally produced from lactose by homo-fermentative lactic acid bacteria such as Lactococcus spp., Lactobacillus plantarum, Lactobacillus casei, Lactobacillus curvatus, and Pediococcus spp. Thus, the characteristics of the pertinent lactic acid bacteria and optimal condition such as temperature, pH, precipitated calcium carbonate addition rate, and content of fermentation for increasing formation yield and purity were investigated. The findings suggested the possibility of manufacturing L(+)-calcium lactate using precipitated calcium carbonate as a calcium source with high value-added instead of commercial calcium lactate.

Jan 1, 2006

By Y. Prévost

The Noranda Continuous Converting Process was commissioned in November 1997 at the Home smelter in Rouyn-Noranda, Quebec, Canada. It has completed over 18 months of successful operation. Excellent team work and technical expertise contributed to achieve targeted production levels and environmental goals after only a few months of operation. The operating results have demonstrated the flexibility of the process in producing blister copper from a variety of copper feed materials including a combination of molten and solid copper matte, reverts and fluxes. This paper describes the startup activities and process optimization tasks performed during the first year of operation of the new Noranda Converter.

Jan 1, 1999

By Daniel Kittelty

A fully instrumented laboratory electrowinning cell has been used to produce nickel cathodes from synthetic solutions containing various impurities in order to evaluate the effects of both metallic ions and organic reagents (from prior solvent extraction and other processes) on the quality of the electrodeposited nickel. The conditions used were typical of those employed in industrial electrowinning operations. The impurities were found to alter the crystal size and shape, induce the development of hydrogen pits on the deposit surface, incorporate as metal hydroxide crystals in the deposit, and alter the internal stress and current efficiency. These effects have been interpreted in terms of previously established relationships between the solution composition and the physical properties of the cathodes. The incorporation of the common metal impurity ions into the deposit have been interpreted in terms of a mass transport controlled reduction or precipitation reactions. In particular, a low concentration of aluminium ions resulted in an initial highly deleterious effect, which was replaced by a positive influence at higher concentrations. A model which involves the buffering effect of the aluminium on the pH at the cathode surface has been proposed.

Jan 1, 2003

By Antonio Martin, Jesus Hurtado, Francisco Jimenez

"Atlantic Copper is one of the largest copper producers in Europe. Its production facilities, including a primary copper smelter and an electrolytic refinery, are located in Huelva, on the southwest coast of Spain. These installations enable the smelting of over 1 million tpy concentrates to produce up to 260,000 tons per year of cathodes and 900 ktpy of sulphuric acid.Since 1970, several improvements have been made at the Converters Area such as modifications of primary hoods, operations with an OPC system, installation of scrap chargers, the recent installation of the secondary hoods and other environmental projects. All these modifications have been aimed at increasing the capacity of our smelter while keeping our continuous environmental commitment.This paper describes the modifications and improvements carried out at the converters area and our proposals for future developments."

Jan 1, 2012

By Jan Petter Maehlen

Solid H-absorbing materials are in focus of ongoing R&D to offer viable solutions for the hydrogen storage and supply systems aimed on use of hydrogen as energy carrier for automotive transportation. Low operating pressures, combined with high gravimetric and volumetric efficiencies, together with fast kinetics of hydrogen release at ambient temperatures (providing conditions for a low energy loss due to decomposition), are the most important features of the ?ideal? H storage material. Hydrides of the light elements are the only possible candidates to build systems with an overall efficiency similar to those accommodating liquid or compressed (700 bar) hydrogen. One promising material from this point of view is aluminium trihydride, alane AlH3 with a gravimetric storage capacity of 10 wt.% H. This work was focused on studies of the crystal structure and thermal decomposition of alane by application of powder synchrotron X-Ray diffraction.

Jan 1, 2006

By Marshall Khan

The Goodfellow Expert Furnace System Optimization Process (Goodfellow EFSOP?) is a proprietary process that uses real-time and continuous off-gas analysis, along with process monitoring to optimize the operation of electric arc furnaces (EAF) for steelmaking. With the exception of off-gas composition, dynamic process measurements within the EAF are not possible due to the harsh operating environment. The Goodfellow EFSOP? system provides a dynamic indication of the operating conditions within the EAF. Continuous measurement of furnace off-gas composition, along with other furnace operating parameters is used to elucidate the fate of chemical energy usage within the EAF including: the evolution of carbon from the molten steel bath; the in-leakage of air into the furnace; the extent of combustion above the molten steel bath and the occurrence of dangerous water-leaks from the furnace cooling system. The ability to measure the process reliably and continuously enables Techint Goodfellow Technologies Inc (TGTI) to implement dynamic process control of combustion within the electric arc furnace and to optimize the overall operation through adjustments to the EAF process based on off-gas measurement. This paper discusses the methodology and results achieved from several recent Goodfellow EFSOP? installations in South East Asia.

Jan 1, 2006

By Bora Derin, Sertac Yazici, M. Seref Sonmez

"In this study, the recycling conditions of waste liquor obtained after the production of tungsten boride powder from calcium tungstate by self-propagating high temperature synthesis (SHS) and the following hydrochloric acid leaching were investigated in detail. Environmentally unfriendly and extremely acidic (pH~ -0.3) liquor consisting of calcium, magnesium, and boron ions was treated with 1 M sodium carbonate solution to precipitate magnesium carbonate and calcium carbonate phases. The obtained amorphous precipitates were heated up to the temperature of 400°C for re-crystallization. As a result, MgO, CaC03 and CaMg(C03)z phases were obtained, while sodium, boron, chlorine ions were remain in the solution. The present study is still in progress.IntroductionSelf-propagating high temperature synthesis (SHS) is one of the techniques used in the production of a variety of advanced ceramics, inter-metallic, organic and inorganic compounds, oxygen free single crystals, and polymers [ 1, 2]. The reaction becomes selfsustaining and propagates in the reactant mixture, after initiation in SHS process. SHS products may contain the mixture of several unwanted compounds and elements. Therefore following acidic leaching process may be needed to purify the target product. In the previous study, calcium tungstate (Ca W04), magnesium (Mg) and boric acid (B20 3) mixture were reacted to produce tungsten boride powder by SHS process according to the Reaction 1. Then, magnesium and calcium containing byproducts (i.e. MgO, Mg3B206 and Ca3B206) found in the SHS product were leached out by using concentrated hydrochloric acid (HCl) solution to obtain pure tungsten boride powder [3].Ca W04 + 0.5B203 + 4.5Mg = WB + 4.5Mg0 + Cao (1)After the leaching, filtrate solution consisting of different amounts of magnesium, calcium, and boron requires additional treatment for the environmentally acceptable disposal.Several works were carried out about magnesium precipitation conditions and kinetics from brines. Rabadzhieva et al. investigated the precipitation of Mg(OH)z from brines by using NaOH as well as caustic soda [ 4]. Turek ve Gnot investigated the precipitation efficiency of Mg(OH)z for the temperature range between 10-40°C, while the reaction was kinetically experimented by Alamdiri et al [5, 6]. Homogeneous precipitation of nesquehonite (MgC03.3H20) by the reaction of MgCli with (NH4)2C03 in supersaturated solutions and factors that influence the precipitation of MgC03.3H20, such as reaction temperature, initial concentration, stirring speed, titration speed, equilibration time, have been studied by Wang et al [7]. The precipitation of Mg(OH)z by calcium hydroxide from aqueous solutions was studied by Baird et al. [8]. Stratful et al. focused on conditions influencing the precipitation of magnesium ammonium phosphate from wastewaters [9]. 1031"

Jan 1, 2011

By K. A. Lewandowski

Agglomeration of ore can be used to immobilize fine particles during heap leaching by agglomerating them into granules. Without agglomeration, the fine ore particles can migrate within the heap, clogging flow channels and producing large areas where access of solution to the ore is very poor. The benefits of agglomeration are well-known in gold heap leaching operations, which can be effectively agglomerated using binders such as Portland cement due to the alkaline leaching solutions used. However, agglomeration has not been very effective in the heap leaching of copper ores, because these ores require an acidic leaching solution. Acid destroys the effectiveness of most binders, causing the agglomerates to disintegrate as soon as the leaching solution is applied. In order to gain the benefits of agglomeration in copper heap leaching, an economical, acid-resistant binder is needed. The two issues that needed to be addressed were: 1) Lack of effective methods for evaluating binder acid resistance before performing expensive, time-consuming, full-scale heap leaching tests, and 2) The vast majority of known binders react poorly to acid conditions, and so a basis was needed for determining which binders are most likely to be acid-resistant. In this paper, the development of two new tests for evaluating binder acid resistance in the laboratory are described. The ?soak test? determines the degree to which agglomerates disintegrate and release fines on contact with acidic solution, measuring the relative quantities of fines released by agglomerates made with different binders under controlled conditions, and serves as a rapid means for comparing large numbers of binders. The ?percolation test? measures several different parameters to determine how a binder is likely to perform in heap leaching: 1) the degree of ?slump? and compaction of agglomerates as they are wetted by acidic solutions; 2) the hydraulic conductivity of the agglomerate bed; 3) the migration of fines through the bed as the solution flows through it; and 4) the quantity of liquid retained in the agglomerates after they are drained. Using these tests, a broad spectrum of binders were examined. Soak testing determined that the most acid-resistant binders were nonionic polymers. Five of these binders were further evaluated using percolation testing.

Jan 1, 2006

By Mark William Kennedy

"Electric furnaces containing high quantities of slag are applied in many areas of pyrometallurgy, often for smelting or slag cleaning. A variety of ratios or rules of thumb have been employed in the industry for the dimensioning of these vessels, in most cases with no clear technical basis.In this paper, several design guidelines are presented (electrode size, spacing, vessel dimensions, energy intensity, etc.) as an attempt to provide some technical basis for optimal dimensioning.Furnace heat generation is related to side wall copper cooler heat losses, in an attempt to establish a methodical design strategy particularly for minimum electrode to wall spacing for modern furnaces with cooled linings.Issues regarding the true nature of heat production in a slag furnace are discussed with regards to the possible impact on accurate modeling and design.IntroductionSlag furnaces have passed through a number of design 'generations' characterized by increasing energy intensities, improved electrode technologies and advancing development in their physical structure or 'furnace integrity' as shown in Table I f 1]. A 3rd generation furnace using ultra-high-power (UHP) graphite electrodes is shown in Figure 1, as a generic example of the types of physical structures present in modern slag furnace designs [1]."

Jan 1, 2012

By D. M. Jones

In May 1999 the first campaign of the BHP San Manuel flash smelting furnace (FSF) will be concluded after having set world records for both campaign length and tonnage smelted for an Outokumpu copper flash smelting furnace. This paper reviews planned process and equipment modifications including: The installation of a new 36,000 mt concentrate storage facility; replacement of the existing dryer electrostatic precipitator with a baghouse; modification of the FSF dry charge bin and feed system to achieve mass flow and uniform feed to the concentrate burner; modifications to the FSF and its ancillary cooling systems; modifications to the waste heat boiler and offgas handling system to increase gas handling capacity and improve process efficiency;- and improvements to the FSF fugitive gas collection system. A brief review of the planning and execution of the scheduled 45 day shutdown is also given.

Jan 1, 1999

By M. Potesser

In the primary and secondary copper industry the anode furnace is the most important process step in the refining procedure to reach an enhancement in value and quality of the copper by a selective oxidation and reduction. By combining the advantages of the conventional tilting hearth anode furnace and the benefits of the drum type anode furnace a new aggregate was developed and patented. The cross-section of the furnace is elliptical and the whole unit is tiltable. During the melting period, the contact surface between the burners and the bath or the scarp is enlarged - an increased energy input is the consequence. For the refining period the furnace is rotated, whereby a high bath level is guaranteed. Due to the longer residence time of the gas in the copper melt, not only the gas consumption is reduced but also the efficiency/quality of the refining process is improved. This investigation shows a metallurgical comparison between the new anode furnace concept with the elliptical profile/cross section and the conventional, tiltable hearth anode furnace as well as the drum type anode furnace. The CFD modeling of the currents in these different furnaces delivered helpful data to compare the geometry of the different furnaces. The investigation covered the refining of blister copper from primary metallurgy, from secondary metallurgy as well as from a mixture of both copper melts. The paper underlines the possibilities for a reduction of the tap-to-tap time and for an increase in production capacity, which can be achieved by applying the new furnace concept in comparison to the conventional furnaces.

Jan 1, 2006

By Karel Verscheure

Reliable furnace cooling technology is a domain of increasing concern to the pyrometallurgical industry as it can significantly increase process intensities, productivity and campaign times of furnaces. Although there are many advantages in using cooling systems, they also impose a variety of problems mainly related to safety, heat losses and sustainability of the operations. The choice of cooling system is hence a matter of trade-offs and differs for every metallurgical application. This paper gives a review of different cooling designs used in the ferrous, non-ferrous and alloying industries. Additionally, the paper systematically reviews aspects of materials selection, manufacturing, installation, water quality and furnace monitoring when using water cooled refractories.

Jan 1, 2006

By S. V. Subramanian

The tool material and the machine design for high speed machining are well advanced over the last decade but the steel design has lagged behind. The paper examines the design of steel in order to control the sliding tribology for high speed machining under dry machining conditions. In high speed machining of steel, accelerated chemical wear of the tool occurs once atomic contact is established at the tool-chip interface, resulting in poor tool life even with high performance tools such as cubic boron nitride. Recent research has confirmed the occurrence of nanocrystalline grains in the interfacial layer of the chip at the tool-chip contact. The volume percentage of grain boundary is increased significantly (10 to 30%) as the nanocrystalline grain size is decreased well below 30 nm. The solubility of tool material into the nanocrystalline grain boundary is two or three orders of magnitude greater than in the crystal lattice. Further the kinetics of diffusion in the grain boundary is seven or eight orders of magnitude greater than in the crystal lattice. Enhanced nanocrystalline grain boundary diffusion occurring in the interfacial layer at the tool-chip contact causes the accelerated chemical wear. Significant improvement in tool life could be achieved by engineering glassy oxide inclusions in steel, designed to self-lubricate the tool-chip interface in-situ at higher cutting speeds. Thus the control of sliding tribological condition at the tool-chip interface is key to suppress nanocrystalline layer formation at the tool-chip contact and hence prevent accelerated chemical tool wear. Sulfide inclusions are designed essentially to promote chip fracture. In addition, sulfide inclusions are designed to act as a diffusion barrier at the tool-chip interface. The application of inclusion engineering concepts to enhance the tool life in high speed machining will be demonstrated with a suitable case history.

Jan 1, 2006

By Min Chen, Nan Wang, Zhen Tian, Yingying Shen

"The enrichment behavior of phosphorus in CaO-SiO2-FeOx-P2O5 slag was studied by making an investigation on the distribution of phosphorous content in slag and 2CaO·SiO2 phase. The research results showed that the existing 2CaO·SiO2 solid particles in slag were the sites for the phosphorous enrichment. The enrichment process of phosphorus in CaO-SiO2-FeOx-P2O5 slag can be recognized as: mass transfer of phosphorus from bulk slag toward the surface of 2CaO·SiO2 particle, superficial dissolution reaction of phosphorus to 2CaO·SiO2 and diffusion of phosphorus through the product layer of 2CaO·SiO2-3CaO·P2O5 solid solution to the inner of 2CaO·SiO2 particle. Compared to the 2CaO·SiO2 particles with larger size (500µm to 1000µm), the completion time of enrichment was shorter for the particles with smaller size (less than 50µm).IntroductionDuring ironmaking and steelmaking, significant amounts of slag are produced. Contrast to the high utilization of ironmaking slag, the treatment of steelmaking slag is more difficult and challengeable, and therefore, an alternative approach is to recycle the steelmaking slag inside the ironmaking and steelmaking process itself. The main limitation to the reuse of steelmaking slag inside the process is that the refining process may be aggravated caused by the phosphorous accumulation if it is used in the blast furnace burden [1]. At the same time, the phosphorous content of steelmaking slag (approximately 1%~5% P2O5) is too low for it to be used as raw material for fertilizer [2, 3]. Moreover, owing to the diminishing supply of global iron ores with low phosphorous content, the control of phosphorus in iron and steelmaking processes has become an increasing problem, and as a result, more amounts of high phosphorus containing steelmaking slag are produced. Therefore, a valuable approach is quite appreciated in which the steelmaking slag is recycled within the ironmaking and steelmaking process and at the same time, the high phosphorus-containing phases in the steelmaking slag, suitable for use as fertilizer can be separated and recycled effectively [4]."

Jan 1, 2011

By Itsuki Uehara, Hiroyuki T. Takeshita, Tetsuo Sakai, Nobuhiro Kuriyama, Hideaki Tanaka

"AB5 type hydrogen storage alloys (A: rare earths, B: transition metals) are extensively applied to a negative electrode of a nickel metal hydride (Ni-MH) rechargeable battery for portable electric equipments, electric vehicles, hybrid vehicles etc. Performance of a hydrogen storage alloy electrode is affected by various factors, microstructure and surface composition of the alloy and structure of the electrode as well as composition of the alloy. Control of those factors enables us to commercialize the Ni-MH battery in various field.IntroductionA Nickel-metal hydride (Ni-MH) battery has been extensively developed because of (1) good compatibility with a nickel cadmium (Ni-Cd) battery, (2) high energy density (1.5-2 times higher per unit volume than a Ni-Cd battery) and high dischargeability, and (3) low environmental pollution. The charge/ discharge reactions can be written as [l, 2,3]:(+) Ni(OH)2+OH- = NiOOH+H2O+e· (E=+0.490V NHE),(-) l/6LaNi5+H2O+e-· = 1/6LaNi5H6+OH- (E=-0.828V NHE),where E° is a standard potential of an electrode vs. normal hydrogen electrode (NHE). Because of the above advantages of a Ni-MH battery, the battery have been widely used as a power source of portable computers, cellular phones, electric vehicles (Toyota ""LAV4L EV"", Honda ""EV Plus"" etc.) etc. Some hybride vehicles (Toyota ""Prius"" and Honda ""INSIGHT"") and fuel cell vhehicles (Toyota ""FCEV"") are power-assisted by a high-power Ni-MH battery. In 1999, the production of Ni-MH batteries reached 870 million cells in Japan. Most of commercialized NiMH batteries are incorporated with rare-earth-based AB5-type hydrogen storage alloy as a negative_ electrode. The production of rare-earth-based alloy is estimated to be approximately 8000 tons.The battery performances of the Ni-MH battery, for example, capacity, durability (cycle life), dischargeability (kinetics) and selfdischarge, ate closely related to the metal hydride· (MH) electrode, especially, the hydrogen storage alloy in the electrode. Substitution of alloy components, heat treatment, and surface treatment in order to change surface and bulk structure of hydrogen storage alloys have been examined by us and many reseachers in order to improve the performances of MH electrodes. This paper is a review of our and their efforts to improve performances of MH electrodes."

Jan 1, 2000

By Ludwig Hermann

"Phosphorus is required by every cell of living organisms and essential for plant growth. It is a non-renewable resource that must be mined from natural deposits, going gradually into depletion. Abundant secondary resources are available in sewage sludge and meat and bone meal, with the highest exploitable P concentrations in ashes that remain from their widely used combustion with energy recovery. ASH DEC has successfully removed heavy metals and transformed sewage sludge ash into a marketable P fertilizer by application of a thermo-chemical treatment process. Pilot scale investigations in which ash was treated proved that generally heavy metal limits required by fertilizer legislation can be attained. To achieve a high P availability for crops – an essential fertilizer quality feature – was a more challenging R&D task. Our presentation demonstrates the scientific approach and R&D results that lead from assessment of market requirements to licensed products.IntroductionPhosphorus (P) is required by every cell of living organisms. It is one of the major elements for plant nutrition and therefore essential for crop production. P supply in plant nutrition depends entirely on external inputs into soils [1]. This is achieved by P-fertilizers deriving from rock phosphate deposits that are gradually going into depletion. Serious prognoses anticipate that rock phosphate will be the first low running resource in the world [2]. In the EU, last year 2.530 kt of phosphorus (P2O5 in fertilizers) was consumed and only 313 kt (P2O5 in rock phosphate) was mined. Since 2007, rock phosphate prices have increased by 500% because of a tight supply situation [3].For these reasons, P recycling is becoming an increasingly important issue. Suitable secondary raw materials with regard to their high P-content and abundance are sewage sludge and meat and bone meal. In the EU 989 kt P2O5 are accumulated annually in theses materials, of which 632 kt P2O5 are permanently lost to landfills and other forms of disposal. The main reasons for their limited recycling are concerns on heavy metal contents and organic pollutants that may incite health hazards. As an additional shortcoming, the availability of P from these materials to plants is poor and storage and transportation are problematic issues [4, 5]."

Jan 1, 2008

By Per Anders Eidem, Merete Tangstad, Jens Davidsen

"During excavations of submerged arc furnaces producing silicomanganese, silicon carbide (SiC) has been found. Contributing to the size of the inactive area of the furnace, the active area of the furnace where reactions occur will decrease, thus reducing the potential for pre-reduction in the furnace.This work studied the formation of SiC from the liquid-solid reaction between slag, metal, and metallurgical coke. Slags and metals with different levels of silica (S1O2) and silicon (Si) have been studied. The slag and metal has been heated together with coke, and the samples investigated by microprobe. The results show that SiC was formed on the coke particle through reactions with both slag and metal. For the metal, the carbon most likely diffused through the SiC to react with Si in the alloy. SiC formation with slag is likely to go through the reduction of Si02 to Si.IntroductionToday, Silicomanganese (SiMn) is produced in submerged arc furnaces (SAF) by reduction of S1O2 and manganese oxides, mainly with metallurgical cokes. Typically, the tapped metal has a silicon content of 17 - 20 wt.%. To achieve higher levels of Si, the metal can be refined by adding off-grade silicon metal, yielding low carbon SiMn. [1]. What is believed to be SiC that has been found during dig-outs of SiMn furnaces producing high silicon alloy. It is possible that excess amounts of SiC in the furnace cause operational problems, since SiC will occupy furnace volume. As SiC accumulates, the active volume of the furnace will decrease, increasing the flow of material and gas in the active areas of the furnace. Formation of SiC is inevitable, so it is desired to keep the formation as low as possible. To be able to control the formation of SiC, one has to understand the basic mechanisms."

Jan 1, 2012