Search Documents

By Kazuyo Yokoyama

New environmental assessment model based on the Waste Input-Output analysis has been developed and applied for the "Landfill mining activity". "Landfill mining" implies the digging up of the landfilled wastes, the recovery of valuable material and energy resources and, thus, the reuse of the saved space as a new landfill site. In this study, the landfilled wastes are assumed to be treated by the gasification/melting processes. Two kinds of reactors, the fluidized bed type (FB) and the shaft furnace type (SF), have been considered in this work as the typical gasification/melting processes adopted in Japan. In FB, the dug-up wastes are heated in the sand fluidized bed zone under reducing atmosphere, Fe and Al are recovered in the metallic form, and then, the gasification/melting of residues is made in the second zone. In SF, the waste is charged in the high temperature coke bed, and the gas is recovered together with molten metal and slag. Both processes generate electric power by the recovered heat and fly ash as waste to landfill. It has been found in this study that the both processes can reduce the total volume of waste and save the available landfill space. SF seems to have higher potential for decreasing volume of wastes because of less emission than FB while FB has great benefit to recover metallic Fe and Al individually. The results of scenario analysis have also indicated that the landfill mining activity is effective for sustainable management of landfill sites.

Jan 1, 2006

By Mark E. Schlesinger

A substantial database exists for the thermodynamic properties of many antimonide compounds, but these have rarely been compiled or critically discussed. An abbreviated version of a full?scale review of the thermodynamic properties of binary antimonide compounds is presented, focusing on the choice of experimental techniques.

Jan 1, 2006

By A. V. Tarasov

One or more of the main alloying metals, i.e. copper, silicon, nickel, magnesium, zinc and other metals can form a composition with aluminum, by dissolving in the latter. The thermodynamic computations have indicated that within a range of temperatures from 700°C to 1300°C the reactions of molten aluminum with zinc and nickel oxides are shifted toward formation of free metals because it is possible to use the main alloying metals, i.e. zinc and nickel, in the form of inexpensive intermediate products and waste. The laboratory studies conducted have confirmed a possibility for production of aluminum alloys using intermediate products in the form of oxides of alloying metals.

Jan 1, 2006

By Olga A. Gomon, Alexey N. Lozhko

The technology of heat treatment for metal frequently includes multiple fast heating and cooling of the products surface. If the product is heavy-weight or long-size, its moving from a zone of cooling to a zone of heating and return require a long time. Other important condition of ensuring qualitative surface at heat treatment is intensification of cooling phase. It is known that turbulization of a flow activates heat exchange and increases efficacy of cooling without increasing volume flow rate of water. Additional difficulty is to ensure the regularity of heating and cooling on length of a product. The technology of cyclic heat treatment of rolling products, at which mobile zone of turbulent heat exchange is formed on the surface of a product, was developed and realized. The submission of water occurs through to face spray systems. Each of the systems has six long-range atomizers, which are located circularly. Two flows of water move towards one another along a surface of a product. When they collide, the right zone of turbulent heat exchange creates heat transfer in this zone of 10-15 time more intensive than on other surface of a product. The effect of moving turbulent zone on length of a product is reached by changing the proportion of volume flow rate of water, which is created by face sprays. The speed of movement for turbulent zone along a surface of a product is chosen so, that the cooling takes place on a small depth only. Then after passing the turbulent zone over a determined site of a surface, its temperature recovers fast owing to hot internal layers. The parameters of process were determined by mathematical simulation of cooling in an installation. The equations for dynamics of movement of collision point of flows, which were received this way, are interesting supplementary products of research. The experiments show that frequency of movement of turbulent zone is an important technological parameter. It defines mechanical properties of a surface and should be chosen depending on a profile of product and metal grade. The results of comparison of mechanical properties of a surface of various rolling products, which were received by developed and conventional technologies, are described in this report. Dependence of regularity of mechanical properties on frequency of movement of turbulent zone is adduced.

Jan 1, 1998

By K. P. Nishad

The origin of many casting defects can be traced at the mold filling stage. Entrapped air/gas pockets and oxide film formation are notable examples. In the present work, the mold-filling process is simulated using a mathematical model, built on a multi-physics based commercial package PHYSICA. The simulation code has the capability to solve multi-phase problems. The numerical model addresses a complicated dynamics of filling operation including free surface flow and subsequent flow behavior and is based on conservation of mass and momentum. The Free surface is modeled using the scalar equation method (SEM). The model is validated with benchmark experimental results from the literature. The role of turbulence and the pouring rate on variables affecting sites prone to oxide film formation are investigated using a simple but novel technique. Key findings of the work are presented.

Jan 1, 2006

By Corby G. Anderson

Today, with a stringent economic and environmental climate prevailing in the copper business, there is increased interest in evaluating new processing alternatives for production. Hydrometallurgical pressure oxidation of copper concentrates is one of the more viable approaches and several technological candidates have emerged. Of these, an overlooked but industrially proven methodology utilizing nitrogen species catalyzation in the oxidizing pressure leach system may prove to be a feasible process alternative for the future. In this paper, the history of the system and its application to chalcopyrite concentrates will be outlined. In particular, a methodology for effective treatment of precious metals bearing chalcopyrite concentrates via partial oxidation at low temperatures and pressures will be discussed. Finally, the perceived economics of this unique industrially proven process will be delineated.

Jan 1, 1999

By Weyman Dunaway

This paper will present a description of the development and commissioning of the world?s most efficient process for manufacturing high purity aqueous zinc bromide. The method for making aqueous zinc bromide from metallic zinc and bromine comprises contacting zinc with bromine dissolved in a reaction solvent containing a metal halide salt. The reaction temperature is maintained at less than 60°C. The reaction solvent preferably comprises an alkali, alkaline earth, or transition metal halide; the halide salt preferably comprises a chloride or a bromide. One preferred method includes the step of recirculating the zinc bromide product stream back to the reaction vessel. The reaction vessel can be either a one stage or a multiple stage reactor. The resulting product stream is a high density aqueous zinc bromide solution. The process is so novel that Tetra Technologies, Inc. was awarded US Patent Number 6,036,937.

Jan 1, 2006

By Migen Dibra

Antitrust and competition laws are designed to protect the free markets and promote competition in order to assure a dynamic and efficient economy and to provide competitive prices for quality products and services. They apply to mergers and acquisitions as well as to joint ventures especially among competitor companies who possess market power and these include collaborations on research and development. If it is determined that these actions are likely to substantially prevent or lessen competition the courts might dissolve, stop, alternate them, etc. Two new factors affect this process today: The role of new technologies and the markets globalization. They both have a considerable effect on the way these laws are interpreted by the courts and on their eventual amendments in order to reflect the new reality. A new applied technology and the globalization separately or together may change the factors that determine how anticompetitive a merger or acquisition between competitors may be and may also serve as a basis for amending the antitrust and competition laws. In this paper, a short review of the recent mergers and acquisitions of various companies has been carried out along with an abridged analysis of the current antitrust and competition laws in USA, Canada and European Union in the view of their capacity to handle the new reality. Some related court decisions are also examined and several examples are given in order to illustrate the influence of new technologies and globalization in interpreting the existing laws and on their amendment possibilities.

Jan 1, 2006

By H. Tan

?Preg-robbing? is the active adsorption of gold from cyanide solution by the ore components. The role of carbonaceous coatings on chalcopyrite surfaces in the preg-robbing of chalcopyrite has been investigated by using pure chalcopyrite and a copper concentrate. Activated carbon and graphite were chosen as representative carbonaceous contaminants. It was found that the carbonaceous coatings enhanced the preg-robbing of chalcopyrite. Activated carbon coating increased gold adsorption onto chalcopyrite to a lager extent, in comparison with graphite coating. In the preg-robbing of the copper concentrate, gold adsorption was increased to larger extent at finer particle sizes and at higher contents of activated carbon or graphite. The preg-robbing of chalcopyrite was reduced or eliminated, depending on the concentrations of free cyanide. However, the gold adsorption on the carbon and graphite coated chalcopyrite could not be avoided even at higher cyanide concentrations, and this adsorption was solely attributed to the carbonaceous coatings. Zeta potential studies indicated that the carbonaceous coatings reduced the negativity of the chalcopyrite surface charge. As shown by SEM analysis, gold not only accumulated at the edges and defect sites, but was also spotted on the smooth surfaces of chalcopyrite with carbon or graphite present. XPS results revealed that gold was strongly reduced on chalcopyrite surfaces, with the sulfide ions of the chalcopyrite being oxidized to elemental sulfur. Diagnostic elution indicated three mechanisms contributing to gold take-up by chalcopyrite, i.e. gold reduction, physical adsorption and chemical adsorption.

Jan 1, 2003

By W. Gong

Their outstanding thermal stability and high energy product make Sm(Co,Fe,Cu,Zr),-type alloys attractive for advanced applications. The near net-shape production of Sm(Co,Fe,Cu,Zr), bonded magnets make them potentially superior to any magnets made by sintering. Although pioneering work done by Shimoda et al. and other investigators provide insights on the proper compositions and process control of this alloy system, additional work is still necessary to improve our understanding of alloy behavior at various processing stages and to increase the production yield during powder processing. In this paper we report on the development of anisotropic Sm(Co,Fe,Cu,Zr), alloy powders for the bonded magnet application. Our focus is on the development of a moderate coercivity powder requiring a relatively low magnetizing field to charge the magnets to their optimum Br, Hci and BHmax. The magnetic properties are related to the evolution of the microstructure at various processing stages and the average particle size and size distribution of powders.

Jan 1, 1997

By Etsuro Shibata

For the treatment of huge amounts of the sulfur which is from the earth by both natural and man-made activities, a harmonized sulfur cycle was presented. The man-made sulfur cycle which includes sulfur circulation from oil, coal and ore was analyzed in detail based on the recent world sulfur trend. Then the man-made cycle was compared with the natural sulfur evolution such as volcano. Finally, the harmony in both natural and man-made sulfur cycles was discussed.

Jan 1, 2006

By F. A. Fasoyinu

The mechanical properties of yellow brass (C85800), high strength yellow brass (C86300), and high manganese brasses (C99700 and C99750) cast in permanent molds have been studied. The tensile properties as well as fracture and impact toughness of these alloys are strongly dependent on the chemical composition. Alloys and/or compositions exhibiting relatively high zinc equivalent often exhibited high ultimate tensile strength and yield strength with significant reduction in ductility (% elongation). In order to achieve optimum properties with a good balance between strength and ductility, a calculation of the zinc equivalent before alloy preparation can be useful.

Jan 1, 1999

By C. O. Bounds

The performance of AB5-type alloys for hydrogen absorption including the electrochemical absorption as an electrode for rechargeable batteries has been demonstrated' to be a complex function of the composition, microstructure and surface condition. The compositional studies have focused primarily on substitutions for Ni on the B-site (e.g. Co, Al, Mn, etc.). This current study examines the effect of rare earth substitutions for La on the A-site and considers both other "light" rare earths (Ce, Nd, Pr) and "heavy" rare earths (Dy, Sm, etc.).

Jan 1, 1997

By T. T. Natarajan, Nagy EI-Kaddah

"Numerical simulation of electromagnetic confinement systems generally requires large CPU time due to the strong coupling between the electromagnetic and the free boundary problems. The present paper examines the accuracy and the computational efficiency of the most common numerical schemes used in modeling such systems. Levitation melting was taken as a test case. In this study, a comparison was made between the finite element and surface integral methods for electromagnetic field calculations. The computational efficiency of Lagrange and the modified Hestenes methods for solving the free boundary problem were investigated. The convergence of the Lagrange method was found to be much faster than the modified Hestenes method. It was also found that finite element method not only gives accurate solutions, but faster convergence to the final equilibrium shape than the surface integral method. The applications and the limitations of these techniques in modeling electromagnetic confinement systems will be discussed.IntroductionIn recent years there has been a growing interest in the use of electromagnetic forces for confinement of molten metals as a means to eliminate molten metal contamination during melting and to improve surface quality of cast products. Continuous casting of metal without contact of a mold is now a reality, and is being commercially applied for casting of aluminum slabs /1/, and copper rods /2/. New applications of electromagnetic confinement in melting and casting include containerless melting (Magnetic Suspension Melting) /3/, edge containment in twin roll casting, and meniscus shape control in continuous casting of steel /4/.Modeling of confinement systems involves the determination of the electromagnetic field and the equilibrium shape. These two problems are strongly coupled due to the dependence of the field on the shape of the melt. While significant advances have been made in computational electromagnetics /5/, the application of developed computational techniques to electromagnetic confinement problems is not a simple task. The principal difficulty in using these methods is that the solution domain is not known a priori. due to coupling between the electromagnetic field and the free boundary problems. These two problems have to be solved simultaneously, leading to an iterative solution procedure. As a result, numerical simulation of electromagnetic confinement systems are computationally intensive with computational time at least an order of magnitude larger than the fixed domain problems."

Jan 1, 1994

By Frank Field, Randolph Kirchain, Elisa Alonso, Richard Roth, Nathan Fleming

"High material prices and price uncertainty can be harmful to manufacturing firms. Increased use of recycled materials, industry-wide, can lower both material prices and price variability; moreover, increased recycling decreases the use of primary material, which mitigates price increases due to scarcity effects. These stabilizing and price lowering effects are explored using an Aluminum industry model. We show that (a) increased recycling leads to smaller price fluctuations in the presence of a primary metal supply perturbation, and (b) that the more substitutable the secondary metal is for the primary metal, the lower the overall material price is.IntroductionThe price of an industrial metal is expected to be a function of both the marginal cost of extraction and its scarcity[l-2]: where scarcity can be defined as the degree to which anticipated demand exceeds the known supply. Recycling end-of-life metal increases the apparent supply of the metal, or-in a functionally equivalent, but alternative conception-lowers the demand for primary metal; this lowers primary metal scarcity and should, theoretically, reduce its price. To the extent that this theoretical prediction holds true, recycling can provide benefits to consumers of industrial metals in the form of lower prices.Using a platinum industry model, prior work by Alonso[3] has shown that increased industrywide recycling can reduce metal price volatility because the secondary metal production (a) offsets virgin metal depletion, and (b) responds to supply-demand balance fluctuations more rapidly than the primary market. However, Platinum is not a typical industrial metal in the sense that secondary metal is perfectly substitutable for primary metal: Both primary and secondary platinum metal are functionally equivalent and have a common price. Other metals, such as secondary aluminum which is used as an example case in this study, contain varying degrees of other elements that were either intentionally added, or were inadvertently mixed in with the metal during the scrap recovery process. Consequently, different grades of scrap exist that have different profiles of elements in their composition. Depending on their particular profile of elements, more or less of a given grade can be used as a mass fraction of the final alloy-the secondary metal is not perfectly substitutable for the primary metal. For the purposes of this paper, the aluminum mass fraction of the final alloy that can be made up of secondary aluminum is termed the secondary substitutability of that grade in that alloy."

Jan 1, 2011

By Brommerm Tracey, Britt Elin Gihleengen, Elsa Olivetti, Hans Ole Riddervold, Randolph Kirchain, Geir Øyen

"Compositional uncertainty in secondary materials and variable processing conditions inhibits secondary material utilization in the production of aluminum alloys. Efforts to implement optimization models that direct batch planning have limited industrial presence due to factors such as the insensitivity of these optimization models to dynamic plant circumstances. This paper describes a chance constrained model formulation that generates lower cost, robust batch plans with significant flexibility towards changes in processing conditions. The principal attribute of the chance constrained formulation is its inherent mitigation of risk by diversifying the batch plan. This paper compares aluminum remelter batch planning using the chance constrained formulation with a traditional deterministic model and a manual batch planner. With the expectation that volatile material prices, restricted scrap material availability, and pressure by consumers and legislation for increased recycled raw material input will continue in the future, batch planning tools that inherently diversify a production portfolio will become increasingly advantageous for industrial aluminum remelters.IntroductionAluminum remelters must develop strategies to incorporate lower cost secondary materials into finished alloys to remain competitive amidst increasingly demanding market and regulatory conditions. Determining the optimal combination of incoming raw materials to produce an alloy that meets compositional specifications presents remelters with a complex problem that has driven the development of computational tools commonly referred to as batch planning or blending algorithms. The ubiquity of the ingredient or raw material blending problem in production has motivated ongoing development of batch planning algorithms since the classic nut-mix problem in the 1950's [1]. The most common model formulation for industrial aluminum remelters are deterministic, linear optimization programs [2]. These blending problems determine the optimal combination of raw materials by minimizing cost subject to constraints around demand, availability, and compositional specification. Despite extensive research and moderate computational requirements, batch planning algorithms are inconsistently used in industry. Insufficient incorporation of the complexity of real world remelting conditions into these models provides an obstacle for their implementation [3]. For example, many batch planning algorithms do not explicitly incorporate the impact of compositional variation of the raw materials on overall batch cost. Additionally, they do not allow for endogenous specification of tolerance to error in batch planning, so provide little flexibility where a batch planner would like to incorporate materials of greater uncertainty. Incomplete accounting for quality variability undervalues secondary materials leading to overly conservative use [ 4, 5]."

Jan 1, 2011

By Clodualdo C. Conde

In order for Philippines Associated Smelting and Refining Corporation (PASAR) Corporation to remain a leader in the copper smelting and refining industry, continuous improvements in plant technology are required. Reliable performance of plant equipment is essential for a competitive smelting operation. PASAR is constantly searching for the best equipment and technology to allow us to manufacture products more efficiently. When the Smelter was commissioned in 1993, the Flash Furnace off-gas treatment system was a constant source of problems. There were frequent shut-downs of the electrostatic precipitator due to material buildups on the discharge electrodes and collecting plates. In 1998, the precipitator was successfully upgraded to eliminate the buildup problems and to increase the collection efficiency. The upgrade greatly reduced down time and maintenance, and the enhanced collection efficiency also eliminated pluggage problems and material losses in the Acid Plant. This extensive precipitator upgrade was accomplished during a 30-day Smelter turnaround.

Jan 1, 1999

By Tianyou Huang, Yuan Lu, Haimin Long, Jinwu Kang, Gang Nie

"The distortion of metal parts during heat treatment process is one of the main obstacles in industry to ensure high-quality work and less or no machining allowance, especially for large but thin steel castings such as heavy turbine blades. In the paper, a method is proposed to control the distortion by adjusting heat transfer coefficient of metal parts during heat treatment process. Required heat transfer coefficients can be realized by getting the metal parts into contact with various media such as water spray, insulation felt or materials with different heat conductivity. The control method based on this idea is set up and achieved. By using insulation felt and water spray to change the heat transfer coefficient during the stages of heat treatment process, the results indicate that the proper control time and vary with materials.IntroductionThe distortion of metal parts during heat treatment process is one of the main obstacles in industry to ensure high-quality work and to realize less or no machining allowance [1]. For example, the Three Gorges turbine blade’s distortion is as large as 50mm during heat treatment process. The uneven heating and cooling during heat treatment process is the main reason for distortion [2]. By adjusting heat transfer coefficient of different areas of metal parts, the heat treatment process could be controlled. The temperature variation, direct cause for distortion, could be under control. Loeser Klaus used high pressure gas to achieve uniform heat transfer during gas quenching and proposed the possibility to use ""Dynamic Quenching"" processes where the quenching severity is varied during quenching by stepwise control of either gas velocity or gas pressure [3]. Li Zhichao also suggested minimizing distortion by marking a component into several areas and imposing different heat transfer coefficients on each area [4]. Heat transfer coefficient can be controlled by getting the metal parts into contact with different media such as water spray, insulation felt, air or different heat conduction materials. In addition, the exact time to adjust the heat transfer coefficient is another factor for distortion. A method is presented in this paper by actively adjusting heat transfer coefficient for different areas of metal parts and different stages of heat treatment process to control their distortion. The corresponding experiments have been made by using different metal materials."

Jan 1, 2012

By S. K. Kawatra

"A typical steelmaking facility produced 50,000 tons per year of slag in their hot-metal desulfurization process. This slag had a sufficiently high iron content that it could be beneficiated and recycled in a blast furnace, provided that the slag could be agglomerated into pellets suitable for use as blast furnace feed. In this work, beneficiated slag was agglomerated using both a conventional bentonite binder, and a fly-ash-based binder (FBB) that was formulated by the investigators. The FBB consisted of a combination of highcarbon fly ash with calcium hydroxide activator, allowing the FBB to exhibit binding properties when moistened. It was determined that beneficiated slag agglomerated with FBB had superior compressive strengths compared to slag agglomerated with conventional bentonite binder. The FBB is therefore a satisfactory method of binding the agglomerated slag. Since the fly-ash component of the FBB is commonly discarded as waste, this approach also provides a means for utilizing high-carbon fly-ashes that currently have very little commercial value.IntroductionIn 2006 approximately 72.4 million short tons of fly-ash were produce in the United States [1]. The majority of fly-ash which was used that year was consumed concrete, structural fills, and cement. It is also used in road base, aggregate, and other applications. However, 55.2% of the fly-ash produced in 2006 was not utilized and ended up being sent to a landfill. Essentially all of the land filled fly-ash could be a suitable binder for pelletizing desulfurization slag and other steel plant waste oxide materials. Fly-ash based binders (FBB) have been shown in laboratory studies to be suitable for producing iron ore concentrate pellets of equivalent strengths as those bonded with bentonite [2,3,4]. The utilization of highcarbon fly-ash within the market is important for reducing the volume of currently unmarketable and land filled fly-ashes. FBB would be a much cheaper alternative to the current bentonite binder or organic binders used for iron ore concentrate and would help to reduce pellet costs. Currently, transportation more than doubles the final cost of bentonite since it is produced hundreds of miles from the pelletizing plants, while fly-ash is produced from power plants located nearby pellet plants and steel mills. FBB’s also show promise for use in other high volume applications such as foundry sand mold binders."

Jan 1, 2008

By O. Nakai

In the copper electrorefining process, the quality of the starting sheet is one of the basic factors for producing high quality copper cathodes. A highly automated and advanced facility for the production of copper starting sheets was constructed at the Toyo Copper Refinery in 1992, bringing various improvements into an automatic stripping system using stainless steel mother blanks. In 1998, the refinery expanded the tankhouse by another 128 commercial cells, and introduced 64 polymer concrete cells in a first stage conversion. As a result, the Toyo Copper Refinery now has the capacity to produce 103,200 t/y of cathode copper. Construction has led to great improvements in the materials handling facilities and computer associated short-circuit detection technology. This report summarizes the improvements made in the quality of the cathodes and in plant productivity.

Jan 1, 1999