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By Gi-Chun Han

This study focused on stabilization of heavy metals and removal of chlorine in MSWI bottom ash by artificial carbonation with washing. Artificial carbonation was carried out by applying CO2(g) injection in washing for fractions above and below 4mesh for reuse as construction materials like aggregate, As a result, carbonation with washing could satisfy Korean environmental regulation and remove chlorine in bottom ash more effectively by resolving residual friedel?s salt(3CaOAl2O3CaCl210H2O).

Jan 1, 2006

By Mark Kramer

This paper is limited to treatment of bottom and fly ash waste resulting from WTE and RTE Cogeneration plants, commonly known as trash burners. The body of the paper defines waste generation and conventional treatment schemes. This paper does not identify a best treatment, however, it does offer a general perspective of the treatments to lead the reader to further investigation. Advantages and disadvantages of the ash treatments Is discussed in each treatment section.

Jan 1, 1996

By K. Yamada, T. Takaoka, A. Ozeki, M. Yamaga, Y. Kawai, S. Nishioka, Y. Kikuchi

"Recently, smelting reduction of chromium ore in BOF has been actively investigated as a key unit process for an innovative future stainless steelmaking. The prominent feature of this new process route is energy and process saving, and production cost saving. The development is already in the midst of application to the commercial production, however there still remain the following key technologies to be established for the full use of the process. One is a speed up of the reduction of chromium ore to match with sequential continuous casting, and the other is efficient combustion of carbonaceous materials in BOF to reduce their consumption, and hence to assure the steel quality. High degree of post combustion technology and new charging technology, i.e., ore-coal-flux-oxygen mixed injection, could be effective for those two subjects. In 2000 or beyond, the new process would have become quite popular owing to the establishment of those key technologies.Introduction Since stainless steel was invented, its production has continued to expand because of its attractive combinations of functions of excellent corrosion resistance, good formability, a pleasing appearance, and a wide range of strength levels. New types of stainless steels as well as new applications are continually being developed.Compared to the production of ordinary steels (1), stainless steel production (2,3) shows steady growth worldwide, while the former production remains on the same level, as Figure 1 shows. It can be estimated that future production would show further growth since materials consumer demands are more fashionable, or more functional, which could be satisfied by stainless steels.Thus market needs would be met, if it could be produced with reasonable production cost. The emergence of an innovative production technology is then potentially requested as VOD and AOD processes have emerged, which has saved substantial production cost. This paper describes a possibility of a future stainless steelmaking process, which uses the in-bath smelting reduction of chromium ore in BOF, and which would save production as well as energy cost."

Jan 1, 1988

By Finlay Campbell

Nickel laterite pressure acid leach plants and reduction roast plants have had a checkered history in their engineering, construction, startup and operational reliability. Many potential projects have been the subject of detailed studies over the last thirty to forty years but relatively few have advanced to commercial production. Four reduction roast plants are currently operating, an additional one was partially constructed but never completed, and another was started up in 1974 and shut down after 12 years operation. Three acid leach plants have been built and commissioned in the last five years, trying to follow the example of the Moa Nickel plant in Cuba. An additional acid leach plant project is currently on hold, following limited construction work, its future subject to review by the owner because of potential cost over-runs. This paper attempts to discuss difficulties that may be encountered as a project is developed and will address factors which may affect production ramp-up schedule, long term production performance and overall production success. Comparisons are made with ramp-up performance at other large metallurgical plants that employ some comparable unit operations. Keywords: Caron, PAL, nickel laterite ore, ramp-up, reliability, process development, equipment design, step-out, commissioning, startup.

Jan 1, 2004

By Xiangjun Zuo, Lifeng Zhang

"Printed Wiring Board (PWB) is a platform upon which microelectronic components such as semiconductor chips and capacitors are mounted. It is also called printed circuit board (PCB). In the PWBs, the organic substances are approximately 72%. The main composition of organic substances in PWBs is ethoxyline resin bromide or ethoxyline resin chlorinate. Depending on the different application and design of the PWB, various metals may be used in the manufacturing process, including precious metals such as copper, lead, silver, gold, platinum, and toxic metals such as mercury, cadmium, barium, gallium, cadmium, lead, bismuth. The current paper reviewed the recycling process for waste PWB materials, including mechanical recycling, combustion for energy recovery and different pyrolysis processes, such as vacuum pyrolysis, atmospheric inert pyrolysi and flux pyrolysis process, and hydrometallurgical recycling process.Backgrounds of Electronic ScrapsProduction and use of electrical and electronic equipment (EEE), such as TV sets, computers, mobile phones and many other daily-life items, have dramatically increased over past decades, while the lifespan of many products becomes shorter"". The rapid innovation in technology in past decades has resulted in availability of cheaper and better electronic products in the market. Thus the production of waste electrical and electronic equipment (WEEE) is also increasing, with estimates of 20-50 million tons per year being generated worldwide2), and it is a problem that governments and policy makers have to handle W). WEEE is also called ""E-wastes"" or ""E-scraps"". From the points of view of recycling and the valuable materials in the used EEE, ""E-scrap"" is more appropriate than ""E-waste"" since the used EEE are not real wastes to be dumped but had much benefit to recycle. In the US, it was estimated that over 315 million computers between 1997 and 2004 and 185 million computers between 2004 and 2007 would become obsolete 5). E-scrap is the fastest-growing part of the U.S. garbage stream 6). It is estimated that only 20% of the E-scrap generated within the US is currently collected and treated, with as much as 80% being unaccounted for7)."

Jan 1, 2011

By Robert G. Telewiak

During the past few years, the international nickel industry has taken some important steps to respond to conditions of global production overcapacity, relatively flat demand and low prices. These include the implementation of major cost reduction programs by most producers, closure of some high cost operations and the establishment of the Nickel Development Institute. Consumption in the western world increased by about 7 per cent in 1987 compared to 1986, supplies were less than demand, inventories were low, and late in the year prices increased dramatically. By year-end 1987, most producers were operating at, or close to, their effective capacities. Nickel demand is expected to increase to the year 2000 at an annual rate of about 1.7 per cent, led by increasing usage in the stainless steel sector. If this rate of growth is realized, then there will be need for the effective capacity of the nickel industry to be increased. Producers in Canada have put considerable effort in the past few years into reducing costs - with impressive results. Mining costs, in particular, have been reduced dramatically. While production is still less than the peak years of the yearly 1970's, it has increased substantially from levels of the early 1980's. Over the next few years, production is expected to increase slowly. A key determinant of the level of production in the 1990's could be the effect that regulations on sulphur dioxide emissions have on limiting production.

Jan 1, 1988

By Junji Shibata

Keywords: Synergistic effect, Solvent extraction, Nickel ion, extractant mixture Waste solution from the Ni non-electric plating process contains 4.0 kg/m3 Ni (II), 0.1 kg/m3 Fe (III), 0.01 kg/m3 Zn (II), 48 kg/m3 SO42-, 98 kg/m3 HPO32- and 31 kg/m3 lactic acid as a typical composition. Solvent extraction, cementation, ion exchange resin and precipitation methods may be used for the treatment of this kind of solution. In this study, solvent extraction of Ni (II) is investigated by using two kinds of extractants in order to clarify the relationship between extraction equilibrium (static synergistic effect) and extraction rate (dynamic synergistic effect) for several extractant mixtures. The static synergistic effect does not take place significantly for the extractant mixtures of acidic extractants and neutral organphosphorous compounds, while a large static synergistic effect is confirmed when the extractant mixtures of acidic extractants and nitrogen-containing compounds are used. Nickel ions can be extracted in the wide pH range of 3.0-8.0 without any pH adjustment by using the several extractant mixtures. At the same time, the extraction rate remarkably increases by using the extractant mixtures of acidic extractants and nitrogen-containing compounds.

Jan 1, 2005

By Sergio N. Monteiro

Lignocellulosic fibers obtained from plants like cotton, flax, hemp, sisal, jute and many others are natural materials used, since long time, in basic items such as textile, baskets, roofing and carpets. These traditional natural fibers as well as some new ones are nowadays replacing synthetic fibers as composite reinforcement owing to environmental advantages. The heterogeneous characteristic of lignocellulosic fibers is, however, a limitation for application in composites. The buriti fiber, extracted from a tropical plant tree, is recently being investigated as a possible reinforcement for polymeric matrix composites but no complete information exists regarding its mechanical behavior. The objective of this work was then to carry out a statistical analysis on the mechanical properties? uniformity of buriti fibers. By precise dimensional measurements in association with tensile tests, it was found that the mechanical properties depend on the range of the fibers? dimension.

Jan 1, 2009

By M. Bhattacharya, A. Dutta, P. Barat

"Pinning of dislocations at nanosized obstacles like precipitates, voids and bubbles, is a crucial mechanism in the context of phenomena like hardening and creep. The interaction between such an obstacle and a dislocation is often explored at fundamental level by means of analytical tools, atomistic simulations and finite element methods. Nevertheless, such studies fail to predict the effect on the overall plasticity on account of insufficient information about the underlying statistics of this process comprising a large number of dislocations and obstacles in a system. Here we propose a new statistical approach, where the statistics of pinning at idealized spherical obstacles is explored by taking into account the generalized size distribution of the obstacle along with the dislocation density within a three-dimensional framework. The application of this approach has been demonstrated for dislocation pinning at nanovoids in neutron irradiated type 316-stainless steel.IntroductionPresence of nanoscale obstacles like precipitates, voids and bubbles play a crucial role in determining the deformation behavior of a crystalline solid on account of the interactions between the line defects and such localized obstacles. In the context of the glide motion of dislocations, the obstacles can offer resistance to a moving dislocation, thereby causing a hardening effect [l-3]. In some other cases, inclusions like voids and bubbles can affect the rate of dislocation climb through diffusive [4] and non-diffusive [5] mechanisms. Over the last few decades, numerous studies have been performed to gain an insight of the dislocation-obstacle interactions at a fundamental level. These include the interactions responsible for the hardening effect, in addition to those pertaining to the non-conservative motion of dislocations.Although the elementary mechanisms of the various dislocation-obstacle interactions have been vastly explored and understood by means of analytical theory and numerical simulations, it remains difficult to quantitatively understand their effects on the macroscopic deformation behavior. This is due to the fact that their influence on the gross plastic deformation of a bulk sample would be the collective outcome of a large ensemble of such interactions. As a result, it becomes infeasible to predict the bulk deformation behavior of a material until the statistics of pinning of the dislocations at the localized obstacles is available. In the context of precipitate hardening, some well known attempts to extract the pinning-statistics were made by Friedel-Fleischer [6] and Mott [7] by analytical means, which were later tested through simplified 2-dimensional in-silica modeling [8]."

Jan 1, 2014

By V. M. Lsoitko

Statistical methods of technological mineralogy are used to model processing flowsheets in order to improve ore dressing efficiencies. The procedure involves determining geological and mineralogical characteristics of ores, classifying ore types and metallurgical procedures, and developing computer programs to interpret essential mineralogical parameters from on-stream analysis data. The on-stream analysis data include magnetism, radioactivity, luminescence and assays. The data are interpreted by computer and appropriate adjustments are made automatically in the plant.

Jan 1, 1989

By Regina Krachler, Herbert Ipser

"The principles of the derivation of statistical-thermodynamic models to interpret the compositional variation of thermodynamic properties in non-stoichiometric intermetallic compounds are discussed. Two types of models are distinguished: the Bragg-Williams type, where the total energy of the crystal is taken as the sum of the interaction energies of all nearest-neighbor pairs of atoms, and the Wagner-Schottky type, where the internal energy, the volume, and the vibrational entropy of the crystal are assumed to be linear functions of the numbers of atoms or vacancies on the different sublattices.A Wagner-Schottky type model is used for the description of two examples with different crystal structures:For B'-FeAl (with B2-structure) defect concentrations and their variation with composition are derived from the results of measurements of the aluminum vapor pressure; the resulting values are compared with results of other independent experimental methods.For Rh3~ (with an NiAs-derivative structure) the defect mechanism responsible for nonstoichiometry is worked out by application of a theoretical model to the results of tellurium vapor pressure measurements. In addition it is shown that the shape of the activity curve indicates a certain sequence of superstructures.In principle, there are no limitations to the application of statistical thermodynamics to experimental thermodynamic data as long as these are available with sufficient accuracy, and as long as it is ensured that the distribution of the point defects is truly random, i.e. that there are no aggregates of defects."

Jan 1, 1996

By Hyun Soo Kim, Joon Soo Kim, Myong Jun Kim, Jyothi Rajesh Kumar, Jin-Young Lee

Rare earth materials have an ever growing variety of applications in the modern and hitech technology. They apply to many an industry with crucial materials and they provide numerous a customers with benefits. Rare earth materials utilization increasing day-by-day in the worldwide, at the same time the resources is very limited in many countries like Korea. The present general article divided four sorts such as 1) mineral processing of Korean ore deals the gravity, magnetic separation and froth flotation, 2) decomposition and leaching of concentrates included sodium hydroxide fritting, sodium hydroxide hot digestion, hydrochloric acid leaching, 3) separation and purification of rare earth elements in mixed rare earth chloride solution consists reduction and oxidation method, solvent extraction, 4) preparation of rare earth oxide compound from purified elemental rare earth chloride solution having oxalate salt precipitation by reaction crystallization. The last part consists of a summary of the present study.

Jan 1, 2015

By David Roha, Øyvind Mikkelsen

"Significant resources have been spent throughout the years in the investigation of production of aluminum by carbothermic reduction. Due to the technological challenges involved, the efforts have not yet resulted in a commercial process. An initiative to overcome issues that prevented previous attempts to succeed was taken by Alcoa through the Advanced Reactor Process. The research program has resulted in technical developments which have resolved many of the previous issues. The knowledge about the process has continuously improved through physical and computer modeling as well as by experimentation at various scales. The technical achievements together with improved process understanding have resulted in a reactor design able to continuously operate the process for several weeks at the time, with hundreds of kilograms of alloy in every tap.IntroductionThe Hall-Heroult process has since its invention in the late 19th century, been essentially the only process used for commercial production of primary aluminum. The process has so far proved to be superior to all potential process alternatives and has continuously been improved. Although the Hall-Heroult is a reliable process it also has challenges:"

Jan 1, 2012

By S. J. Hogan, T. William

"By the year 2000, the steel industry, not only in the United States but in the rest of the world, will undergo significant changes. On the other hand, there will be a number of areas in which change will be minimal.The current capacity of the industry worldwide is approximately 800-810 million metric tons. This may grow to some extent, as Third World countries install capacity. However, much of it will be neutralized as the industrialized countries shrink their current capacities.There will be several breakthroughs in terms of technology, some of which deal with the production of iron outside of the blast furnace. However, these processes will not be far enough advanced by that time to replace the blast furnace, rather they will supplement it.In terms of steelmaking and the subsequent rolling process, there should be a number of basic improvements. The strip mills will roll sheets with a very slight variance in gauge, which will give the customers a better product for automatic stamping machines. Ordinary carbon steel, in a number of instances, will be replaced by high-strength, low-alloy steel, which will reduce the tonnage necessary for present-day applications, such as construction.The corporate organization will be significantly changed as joint ventures and mergers will reduce the number of companies, as well as facilities in operation. This will enable the industry to reduce its capital investment and improve operating costs, so that it will be able more effectively to compete with other materials, such as plastics, cement, aluminum, etc."

Jan 1, 1988

By Kiyoshi Shibata, Jun-ichi Hayashi

"Steel making technology poses strong potentials for environmental protection in three direction. One is pollution control on steel making process itself. Japanese steel industry has cut down various type of emission drastically since 1970's. Secondary, those process technology can be applied to reduce environmental burden in other industrial sectors. One of the successful examples is municipal waste treatment facility. Thirdly, development of high performance steel products, such as high strength steel for automobile body, can contribute to improve environmental performance during their use, based on the concept of life cycle assessment. Some examples of the successful development and future task is discussed.IntroductionsStack and smoke used to be a symbol of energy intensive industry such as steel making. But, scenery of steel works and its surroundings have been completely changed, and steel products have been changing, as well. The steel making industry consumes huge quantities of energy and resources. Variety of technical development have been carried out to reduce the pollutant release. The steel industry in Japan has been making direct and indirect contributions to reducing of various kinds of environmental impacts through development of high-performance process and products: Its potential technical capability accumulated in steel making is fundamental and essential infrastructure for the vein systems of our society. In this paper, the activity of steel making industry for better environment is discussed"

Jan 1, 2000

By Musa Karakus

Zirconia-based refractorics arc finding increasing use for specialized applications in steelmaking technology, making optimization of their resistance to corrosion by steelmaking slags more important. Samples of calcia- and magnesia-stabilized zirconia refractories have been exposed to slags in the CaO - FeO - SiO, system at 155WC for the purposes of measuring corrosion rates. Examination by SEM/EDX and cathodoluminescence of the mineralogy of the attacked specimens reveals important clues about the mechanism of attack.

Jan 1, 1992

By T. V. Swaminathan

Monazite sand is normally processed by, the caustic soda route to produce mixed rare earths chloride, thorium hydroxide and trisodium phosphate. Bulk of the mixed rare earths chloride is used for the preparation of FC catalysts. Recently some of the catalyst producers have shown preference to cerium depleted (lanthanum enriched) rare earths chloride rather than the natural rare earths chloride obtained from monazite. Therefore, a process for producing cerium depleted rare earths chloride, cerium p thorium and uranium from Rare earths + thorium hydroxide obtained by treating monazite based on stepwise hydrochloric acid extraction, was developed in our laboratory. The process involves drying of the mixed rare earths-thorium hydroxide cake obtained by monazite-caustic soda process followed by stepwise extraction of the dried cake with hydrochloric acid under specified conditions.

Jan 1, 1989

By M. Ide, K. Takemura, S. Taenaka, K. Shinzawa

"The laser characteristic is strongry dependent upon the stoichometry of forsterite (Mg2Si04) and YSO (Y2Si05) single crystals, because of change in the valency and occupied sites of doped Cr in the lattice so that mole ratios of Mg0/Si02 and Y203/Si02 in the above single crystals must be precisely analyzed. In this study ICP-AES was applied for analyzing the mole ratios. Emission intensities corresponding to Si and Mg or Si and Y were measured at the same time with internal standard method. Preparation of sample solutions, measurement conditions of ICP-AES and interferences by coexisting components were discussed, resulting in excellently precise detennination of stoichometry of the above single crystals.IntroductionIn conventional stoichiometric analysis of single crystals, the stoichiometry is detennined by analyzing each component separately with titrimetry and gravimetry techniques. On the other hand, by stoichiometric analyses using ICP-AES, emission intensities corresponding to components are measured at the same time with internal standard method. Consequently erros caused by variation of analytical condition are canceled out.Cr-doped Mg2Si04 and Y2Si05 syngle crystals are known as laser materials. The change of valency and occupied sites of doped Cr affect the characteristic of single crystal as aleser materials. The change of state of doped Cr.Stoichometric composition of Mg2Si04 is constructed by 2mole of MgO and 1mole of Si02, and Y2Si05 is constructed by 1mole of Y203 and 1mole of Si02. In this study, required analytical precision in component mole ratio is within an error of 0.0010 for Mg2Si04 (CV=0.05wt%), and within an error of 0.0030 for Y2Si05 (CV=0.05wt%) (Table I )."

Jan 1, 1998

By George P. Demopoulos

n this study we have sought to highlight the critical linkage between individual reaction kinetic parameters (usually determined in small bench scale experiments) and large continuous reactor performance by focusing on the industrially significant zinc pressure leach process. To this end a comprehensive mathematical model previously developed for the description of this process was employed. In this paper we have examined in particular how small variations in key kinetic parameters impact on the autoclave&apos;s performance, i.e. attainment of autogenous steady-state temperature, zinc conversion and solution chemistry. The reaction parameters studied were: (i) stoichiometry of the marmatite leaching reaction; (ii) the activation energy of the same reaction, E,; (iii) the rate constant of the ferrous to ferric oxidation reaction, k,; and (iv) the apparent equilibrium constant for ferric precipitation, K,. This parameter sensitivity analysis was done under no oxygen mass transfer control limitations. Model predictions were found to be more sensitive to the kinetic parameters under certain conditions than others. The most dramatic finding was the one related to the small amount of sulfate produced during marmatite leaching. In connection to this it was found that the small percentage (< 5 %) of sulfate produced enhances the autothermal operational stability of the autoclave. The need for accurate kinetic parameter determination under conditions similar to those encountered in industrial zinc pressure leaching was demonstrated.

Jan 1, 1999

By Jiann-Yang Hwang

Hydrogen storage is a critical issue for the hydrogen economy. Current storage technologies are not able to meet the combined gravimetric, volumetric, and system cost targets set by the Department of Energy. To solve the problem, the development of a new material - perhydride ? is proposed. Perhydrides are defined as materials that contain more hydrogen atoms in their molecules than conventional hydrides do based on the valence. This concept is supported by the versatile bonding capability of hydrogen and the recent discoveries in the chemistry of hydrogen clusters.

Jan 1, 2006