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By Jorge A. S. Tenorio, Girley F. Rodrigues, Joner O. Alves, Denise C. R. Espinosa

"Rock wools are mineral fibers composed of amorphous silicates, due to their thermo-acoustic characteristics this material has a broad consumer market in the construction, automotive, and electric-electronics industries. This work studied the recovery of wastes from ornamental rocks (granite and marble) as partial raw materials in the production of rock wools. Residues from granite and marble cuttings are industrial wastes with considerable production and limited applications. These wastes should be appropriately managed because when discharged in rivers or lakes can cause siltation, and also they can cause serious human health problems, such as silicosis. Samples of produced materials with thickness smaller than 500µm were characterized by chemical analyses, XRD, and DTA. Results showed that the rock wools produced using granite or marble wastes have important properties, especially the melting point. This process decreases the extraction of mineral resources and provides a profitable destination for the ornamental rock wastes.IntroductionThe ornamental rocks industry is a sector with large production of wastes. During the granite and marble extraction processes and specifically during the rocks cutting (see Figure 1), approximately 35 tons of powdered rock per month can be produced. These residues should be appropriately managed, because when discharged in rivers, lakes or watersheds, they can cause siltation. Also, these wastes can cause serious human health problems, such as silicosis [1].Currently, the granite and marble wastes are mainly used in civil construction to produce materials in the form of mortar, bricks and tiles. However, due the current produced volumes and the average growth of world production estimated at 6% per year, new applications for these wastes are necessary [2]."

Jan 1, 2011

By F. Patisson

One of the major issues with multiparticle reactors is to handle their multiscale aspect. For modeling, it usually comes to coupling a reactor model (describing the phenomena at the macroscopic scale) with a so-called grain model (simulating the behavior of a single grain or a particle). An interesting approach proposed by H.Y. Sohn (1978) is to use the law of additive reaction times in order to calculate, approximately but analytically, the reaction rate of a particle in the reactor model. Its great advantage, compared to a numerical grain model, is to drastically reduce the computation time, particularly in the case of complex reactor models. This is the approach we retained for modeling the moving bed furnace, a counter-current gas-solid reactor used in the nuclear fuel-making route for producing uranium tetrafluoride from uranium trioxide. The numerical model we developed is 2-dimensional, steady-state and based on the finite volume method. It describes solid and gas flow, convective, conductive and radiative heat transfers, and six chemical reactions involved in the process. The law of additive reaction times is used to calculate analytically the rate of the three principal gas-solid reactions at every discrete point in the reactor. We have demonstrated the validity of this approach by comparing its results with those calculated from a numerical grain model. Also detailed in the paper are the main results of the moving bed furnace model itself and the possibilities of optimizing the process revealed by the calculations.

Jan 1, 2006

By Beatriz Amarai Campos, Jorge Alberto Soares Tenorio1, Denise Crocce Romano Espinosa, Adriana Johanny Murcia Santanilla

"The aim of the present work is to investigate the recovery of nickel from obsolete cell phones printed circuit boards. The printed circuit boards were firstly submitted to a grinding process and then leached in sulfuric acid. Nickel was extracted from aqueous solution using Cyanex 272. Aqueous/organic ratio was 1/1. The effect of both pH and modifier addition on selectivity of extraction was investigated.IntroductionCurrently, electric and electronic equipments (EEE) have become a necessity to the modern life. Associated with this necessity comes the continuous and increasing replacement of those equipments by new ones. The accelerated technology advances are responsible for the generation of electric and electronic waste. This waste can be dangerous not only to human health but also to the environment. Waste of electric and electronic equipments (WEEE) has a variety of components and metals in its composition becoming a potential pollutant to the environment when not properly discarded. Its wrong disposal causes a loss of materials that could be recovered and reused. Therefore WEEE treatment is an important matter because it can assist the reduction of waste generated and the recovery of valuable metals.Printed circuit board (PCBs) is an essential component of EEE and is typically very complex from a chemical point of view. Several metals may be present in its composition, such as cooper, nickel, iron, zinc, lead, tin and silver1''. This characteristic hinders the development of a simple treatment, making it necessary the application of chemical and mechanical processing for their recycling'4'. The UN estimates that approximately 20 to 50 million of tonnes of WEEE are generated worldwide each year."

Jan 1, 2011

By S. Yokoya

With increasing requirement of steel productivity and quality in continuous casting in the conventional casting system using an immersion nozzle, it is very difficult to establish a reasonable molten flow pattern. In order to overcome this difficulty, we propose a new method of imparting swirling motion onto the flow in the immersion nozzle and to control the flow pattern in the mold. Following results have been obtained during the studies. For the case of slab continuous casting mold: High amplitudes of oscillation with a period of 10 to 15 seconds are observed in the outlet flow of the immersion nozzle and meniscus flow in the conventional casting system, while these phenomena are remarkably suppressed using swirling motion in the immersion nozzle, which leads to very calm and uniform flow pattern at the outlets of the immersion nozzle, in the mold and on the meniscus in the mold; For the case of billet continuous casting mold: (1) heat and mass transfer near the meniscus can be remarkably activated compared with a conventional straight type immersion nozzle without swirl, and (2) Quite different mold flow patterns are observed between the divergent and straight immersion nozzles. Heat and mass transport in the mold using the divergent nozzle is much more reasonable compared to that of straight nozzle. The findings, mentioned above, are very useful to control the flow pattern in the slab, and billet continuous casters. Such effectiveness of swirling flow in the SEN on the mold flow has been put into practical use. As a result, remarkable progress on the quality and production of continuous casting products has been observed in practical application.

Jan 1, 2006

By Yoshimasa Oda

The tank house of Tamano Smelter has adopted a high current density electrolysis operation applying PRC (Periodic Reverse Current) method and before 1991, it had materialized both high production capacity of 161,000 tons/year and high labor productivity. However, recent rapid rise of Japanese currency in foreign exchange market has urged us to further exert our efforts in reduction of labor cost. In order to achieve this goal of labor cost reduction, we have completed, in 1994, our phase four production expansion project which incorporated significant re-structuring of the organization and we have accomplished annual production of 191,000 tons/year. This project can be outlined as increase of number of cells for electrode exchange per day in the commercial electrolysis process to meet the increased number of cells and increase of the capacity of impurity treatment process. These improvements were done with minimum installation of new equipment and facilities and with achievements in efficiency and manpower saving of the existing facilities. Together with these improvements, rationalization in the starting sheet section was carried out by changing the material of mother blanks as well as changing their maintenance procedures. At the same time, the crane in this section was modified to enable automatic operation by a fuzzy control. As a result, we were able to save manpower equivalent to 5 operators in this section. With these improvements, the production capacity was increased by 18% and labor productivity by 25%.

Jan 1, 1996

By Pedro Morales C.

From its beginning in the 1970s, the Teniente Converter has consistently achieved continuous improvement, and has contributed to the competitiveness and sustainability of Codelco's copper operations. The later introduction of the Slag Cleaning Furnace technology has helped to create a full technology package, referred to as the Teniente Technology. This paper outlines the features of a new research and innovation program designed to bring the Teniente Technology as a modem, competitive technology into the 21st century. The overall objectives and features of the program are described and discussed. It is fully anticipated that these activities will help position the Teniente Technology as a world-class modem technology, well-integrated and operating in a fully continuous mode in conjunction with the other units at the plant, a competitive technology which operates in harmony with respect to environmental regulations.

Jan 1, 1999

By Lucas L. Costa, Luiz F. Lopes, Ludy C. Motta, Felipe P. D. Lopes, Sergio N. Monteiro, Lara S. Vasconcellos

"Environmentally correct materials like the lignocellulosic natural fibers, which are renewable and biodegradable, are being extensively investigated as possible substitutes for synthetic fiber in polymeric composites. Several natural fibers have never been thoroughly investigated as possible composite reinforcement. The fiber obtained from the leaves of the buriti (Mauritia flexuosa) palm tree is one example. Therefore, the objective of this work was to study the properties of buriti waste fibers, in amounts of up to 30%, reinforcing polyester composites.IntroductionIn the past century, the technological development gave priority to new synthetic materials with energy intensive methods of production. Today, there is a concern that conventional energy source such as petroleum, natural gas and coal are the main responsible for global warming. Therefore, the use of natural materials is gaining attention not only for the saving in process energy but also the renewable and biodegradable characteristics that make them environmentally correct. The lignocellulosic natural fibers extracted from cultivated vegetables like jute, sisal, hemp, coconut, flax, ramie and many others are typical examples. This type of fiber is being extensively investigated as a possible substitute for synthetic ones, especially the glass fiber, as composite reinforcement [1].A relevant example of lignocellulosic fiber substitution is nowadays occurring in vehicles. The automobile industry is applying composites reinforced with natural fibers to replace parts such as panels and seat cushions made of fiberglass or polymeric foams [4], as illustrated in Fig. 1. The practical reasons for this preference are that natural fiber composites present less damage to tools and molding equipments as well as relatively better finishing and less abrasive surface than corresponding parts made, for instance, of glass fibers. On top of these advantages, low cost is probably the main motivation for the industrial interest for natural fiber composites, especially in the case of residual fibers [5] or post-used fabrics such as jute sackcloth [6]. Natural fibers, however, are hydrophilic and will not form strong bonding with a hydrophobic polymer, normally used as composite matrix [1-3]. Another disadvantage is the heterogeneous characteristics of a natural fiber, which is typical of biomaterials. This results in a relatively great dispersion of dimensions and properties values such as the mechanical strength [1-3]."

Jan 1, 2008

By Michael S. Moats, Jan D. Miller, Wlodzimierz W. Zmierczak

"For many, hydrogen in a pure hydrogen economy would be like natural gas in today’s energy economy. Unfortunately, hydrogen’s physical properties are unsuited to the energy market’s requirements in terms of packaging, storage, transfer, and delivery. In this paper, a hybrid energy economy that packages hydrogen chemically on carbon atoms from various sources including recycled carbon dioxide is introduced and discussed. For this new hybrid energy economy to become a sustainable reality, the ability to recycle carbon dioxide and use hydrogen to create an appropriate energy product, such as dimethyl ether (DME), is needed. DME is recognized as a potential next generation, “beyond-petroleum”, environmentally benign commodity for energy storage and distribution. It is expected that to maximize the sustainability of the proposed hybrid energy economy, “green” hydrogen will be utilized. The “green” hydrogen would be created by the electrolysis of water powered by renewable energy sources, such as solar, wind or geothermal heat.IntroductionWith the growing concerns surrounding trends in global warming and increasing concentrations of “greenhouse” gases, such as CO2 and CH4, efforts to mitigate the emission of these gases from industrial sources are growing. With respect to CO2, the demonstrations of various capture and sequestration methods are underway around the world.The sequestration of CO2 is mainly focused on storing the gas underground or deep in the ocean. The Intergovernmental Panel on Climate Change (IPCC) estimates that 2000 Gtonnes of CO2 can be stored underground in depleted oilfields, un-minable coal beds and other geologic features [1]. Additionally CO2 may be stored at the bottom of the ocean. The lure of storing carbon dioxide in depleted oilfields or un-mineable coal seams is that an economic benefit (enhanced oil or methane recovery) can offset the costs of gas capture, transportation and storage. Unfortunately, all of these storage methods have potential for the release of CO2 or CH4 back into atmosphere or creating environmental damage (mobilizing heavy metals, disrupting deep sea ecology)."

Jan 1, 2008

By Guodong Lai, Shixing Wang, Lijuan Chu, Jinhui Peng, Zebiao Zhang

"The beneficiation of poor manganese ores containing phosphate gangue is very difficult by conventional processes, because of the similarities in the physico-chemical properties of the constituent minerals. The shaking table gravity concentration process and concentrated strong acid selective intensified leaching process were used for dephosphorisation of Yunnan manganese ore. The leaching process was effective. The effects of intensified leaching time, solid-liquid ratio and particle size were investigated. The relevant leaching factors were optimized as -0.125+0.088 mm particle size with 68% nitric acid for 24 h when using a solid-liquid ratio of 1:1 at room temperature and atmospheric pressure. Under these conditions, the P/Mn ratio was reduced from 0.0107 to 0.0056, and the grade of manganese was increased from 12.32% to 42.76%. The dissolution of manganese during leaching was negligible.IntroductionManganese and its compounds are widely used in the iron and steel industry as deoxidation and desulfurization agents and as alloying additives [1-2]. Because of the increase in demand, low grade refractory manganese ores are becoming a new source. Many Chinese manganese ores are high in phosphorus, which cannot be used directly for metallurgical purposes. This occurs because phosphorus enters into the metal phase during smelting and its presence sharply deteriorates the mechanical properties of the metal [3-4].Kanungo and Sant [3] investigated the dephosphorization of phosphorus-rich manganese ores by selective leaching with dilute hydrochloric acid. They observed that leaching with dilute hydrochloric acid (0.1-0.6M) could reduce the phosphorus contents to the specified limit of 0.12%. Ye [5] investigated dephosphorization of high-phosphorus manganese ore of the Huayuan type. Using high intensity magnetic separation, roasting and leaching with acid for dephosphorization, as used in the industry, a 40.15% manganese concentrate with a P/Mn ratio of 0.0037 was obtained. Yimin [6] investigated magnetic separation followed by inverse flotation of high-phosphorus manganese ore, and found that the P/Mn ratio could be reduced from 0.046 to 0.002."

Jan 1, 2012

By Luis Velazquez, Andrea Zavala, Nora Munguia

"This paper is aimed at describing the evolutive strategy in which the University of Sonora is following for optimizing the organic and inorganic material life cycle in the products used on campus. The institutional strategy has be oriented towards new patterns of behaviors in order to integrate the principles of sustainability as a guideline for preventing, eliminating, and/or reducing the negative environmental and occupational impacts generated when performing university substantive functions of teaching, research, and outreaching and partnership as well as its management operation tasks.IntroductionThe University of Sonora is the largest and most important university among several other universities in both the city and the state. It is a public university with a 29,792 students in three campuses in the state. The main campus of the University of Sonora is located in the capital city of Hermosillo, which has a population of more than 609,829, in the state of Sonora in the northwestern region of Mexico [1].Despite the fact that in the University of Sonora there were, in the eighties, some projects dealing with environmental issues, there was not until 1992 that the sustainability efforts were really initiated. It happened when the Sustainable Development Group was created in the Department of Industrial and Systems Engineering as a response to the need for adapting the industrial engineering curricula to the challenge of sustainable development [2]. In order to promote sustainability, it has been necessary to cope and break with several university paradigms. For this reason, the strategy for becoming a sustainable university has continuously evolved throughout the years from a simple structure composed by individual and isolated projects to a systematic and integrative Sustainability Management System. Thanks to this evolution, the University of Sonora has won a respectable reputation in the greater community and it is seen in the region as an icon of sustainability promoter. In this sense, the substantives functions of education, research, and outreach and partnership, which are considered supportive and integrative, have also evolved to play a key role for the success of sustainability initiatives.The institution has followed four avenues for becoming a sustainable university; education, research, outreaching and partnership and greening the campus [3]."

Jan 1, 2008

By Congcong Yang, Jian Pan, Deqing Zhu, Yang Zhong

A study of pelletization of one imported chromite concentrate with coarse site, poor ballability and refractory roasting performance was conducted in small scale tests, and high pressure grinding rollers (HPGR) was used to improve the pelletization. The mechanism of HPGR was revealed by means of SEM images and optical microscopy. Compared with the ball milling pretreatment, HPGR pretreatment can not only enhance the ballability of pellet feed but also drop the roasting temperature. Fired pellets, containing proper chemical compositions with high compressive strength of 2917N/pellet and good metallurgical performances, have been manufactured. The mechanism of HPGR reveals that chromite particle surface turns to more irregular after HPGR treatment and more new surface being formed because of more cracks, sharp corners and edges appearing, resulting in higher surface chemical activity, all of which improve the ballability of the chromite concentrate and contribute to the consolidation of fired pellets.

Jan 1, 2015

By Frank Mucciardi, Hujun Zhao, Pietro Navarra

"A heat pipe is a device having a very high effective thermal conductivity in which two-phase flow and heat transfer takes place. Recent research at McGill University has led to a new type of heat pipe that contains a flow modifier. This improvement has enabled the device to operate at the high heat fluxes encountered in the metallurgical industry.This paper summarizes the progress made to describe the fluid flow in the evaporator section of a McGill heat pipe with the goal of understanding how the flow modifier configuration is linked to the film boiling and dry-out limitations. A separated flow model, an instability analysis, a lift-off model and an energy balance model are used to calculate the theoretical CHF with varying flow modifier configurations and operation conditions. A summary of the current work to relate the flow modifier to the dry-out limitation is also given.Determining how the flow modifier affects both the film boiling and dry-out limitation will give insight into improving the flow modifier design so as to extend the operational range of McGill heat pipes in terms of maximum heat flux and heat load capabilities.IntroductionThe McGill heat pipe is a specialized two-phase heat exchanger developed for several metallurgical applications where temperatures and heat fluxes are typically close to or beyond the maximum safe range of conventional cooling technology.Over the last few years, several breakthroughs have brought this device beyond the proof-of concept stage and a series of industrial trials have been performed with success. These trials include two oxygen injection applications for the ferrous and non-ferrous industry [l], and two light metals permanent-mould casting applications [2,3]. Current projects include a blast furnace copper taphole cooling application [4], a copper smelting application and a thermal analysis probe application."

Jan 1, 2004

By Peter Bauer, Klaus Gamweger

"Gas purging systems are well established in nonferrous metallurgy at multiple steps during metal production, including melting, converting, alloying, and metal cleaning. Since the kinetics of all of these stages are positively influenced by using gas purging systems the overall process benefits are substantial. In the aluminum industry, inert or reaction gases are blown into the melt using porous plugs to achieve improved metal grades, higher productivity, and more efficient energy utilization. To enable the most effective application of the process gases a complete package, termed AL KIN, was developed by RHI that includes porous plugs, refractory expertise, gas supply technology, and gas control equipment. This paper discusses the technological and economic advantages of this system and the specific benefits of fuel reduction, production time savings, decreased process gas consumption, and improved refractory service life and maintenance are illustrated using an aluminum slug plant in Austria.IntroductionIn addition to high quality production, increasing productivity is the main goal in many aluminum cast houses to maintain or even strengthen their market position. The Neuman Aluminium Group, based in Austria, North America, and based in Austria, North America, and China, is the largest slugproducer for tubes, cans, and automotive parts worldwide. Recently, a comprehensive improvement program was initiated at the Neuman Aluminium Austria slug plant in Marktl - the main factory and technological centre of the group. The principal goal of the optimization project was to increase the productivity of the strip-casting production. The investment included a gas purging system, ingot preheating equipment, a new insulated launder system, and optimized melting cycles. However, the introduction of the gas purging system was pivotal to the project and has accounted for approximately 50% of the benefits achieved. This paper describes the AL KIN gas purging technology and details the process benefits resulting from the improvements at Neuman Aluminium Austria."

Jan 1, 2009

By Fatbardha Osmani, Skender Osmani

"A system analysis of the resource and environment management (water, energy etc) starts from its definition. Unfortunately, there is not a unique semantics of the mentioned concept. On these circumstances, in this paper the following issues are presented: 1.A short view on the existing concepts of management. 2.A new definition on the concept of management. It is considered as a complex and rational activity on human and natural resources ,environment etc, which starts from a analysis of infrastructure ,technology , etc, mission , alternatives , project etc. and ends to an optimal output. Basing on this definition, the management has two principal components: strategy and policy. The strategy is referred as a blue print program (the same definition as in Game Theory), which contains all the contingency alternatives. , while the policy is referred as a strategy applied into practice. The strategy is the first , while the policy is the second one. The best alternative of a policy is the project, Each strategy has one and only one project. The mentioned definition erases the differences between concept of policy and politics. Each strategy has its alternatives ,the next has its sub strategy and so on, i.e. whatever are going to be the strategy, there are a hierarchy composed by sub strategies up to the simplest strategies applied by a single individual (human beings or robots). The strategy objectives are necessary and sufficient conditions for its realization i.e . the strategy is an optimal activity, in which all resources are integrated and processed . Several strategies could be joined into one( for example the surface water strategies of the Balkan countries) . In this view, the strategy could be globalized into optimal way basing on different criteria’s as social, economic, environmental, their risks and effectiveness etc. etc An example from the water management illustrates the mentioned concepts."

Jan 1, 2008

By Murray Johnston

New measurements have been made on the equilibrium distribution of selenium and tellurium between molten slag and metal phases. Distribution coefficients of Se and Te between magnesia-saturated calcium ferrite slag and copper or silver alloys were measured over the temperature range 1473 and 1673 K under controlled oxygen patrial pressures of 10-11 to 10-0.68atm. The results demonstrate that the minor elements are present in the calcium ferrite slag as the selenide (Se2-) and telluride (Te2-) respectively, up to a PO2 of 10-6 atm. As conditions become more oxidising, Te undergoes a transition to the divalent oxide whereas Se does not. Increasing the temperature was found to enhance partitioning of the minor elements to the slag. In terms of activities, at 1573 K, Se showed strong negative deviation from the ideal behaviour in the slag, while Te showed only slight positive deviation.

Jan 1, 2006

By T. W. Gonzales

The refractory performance of Peirce-Smith converters is considered to be mainly determined by effects of process control and refractory installation design. BHP Copper has shown that, over the last four years, considerable improvements in tuyere line life can be affected .by maintaining a uniform temperature in the operating converter and by ensuring sufficient and specific placement of expansion allowance in the construction of the refractory brickwork. A combination of optimized crane availability, rapid matte transfer, converter operating practices, new refractory installation techniques and applications has minimized out-of stack time. In addition, larger diameter tuyere pipes and hard piping have increased blowing rates and lowered cycle times, which has resulted in a tuyere line performance in excess of 62,500 tonnes of blister copper before maintenance is required. This paper discusses the refractory installation design changes that were made to increase tuyere line life.

Jan 1, 1999

By Petr Sulovsky, Pavel Leber, Jaroslava Ledererova, Miroslav Svoboda

"The properties of raw materials used for the production of building materials play an essential role in their choice. Industrial waste materials can in some cases improve the performance of new building materials, when compared with classical raw materials. The addition of waste can however negatively impact some of the building material´s characteristics, influencing its stability, service time, durability, and can introduce undesirable variation of certain characteristics over time. It is necessary that each secondary raw material intended for such use be thoroughly investigated in terms of its chemical, physical, and mechanical properties, with special attention paid to the risk components and risk parameters. It is necessary to make many- sided technological tests in relation to the required characteristics of the resulting materials for each chosen application. Moreover, the limit values for the critical (risk) parameters, which the given secondary raw material must satisfy to be used in a specific technology, need to be defined. Introduction The risk components in the industrial waste materials to be used in the production of building materials fall into two groups: - components that pose a risk of development (instant or delayed) of a process deleterious to the utility properties and durability of the resulting materials. Such processes include volume change (expansion as well as shrinkage), alkali-silica reaction, delayed ettringite formation, thaumassite attack, aggressive carbonation, etc. - elements or components that can, if released from the waste-containing building material, pollute the environment. They involve the so called potentially hazardous elements as well as compounds like fenols, PCB, PAHs etc. From the viewpoint of the presence of both groups of risk components, the wastes can be classified as: • environmentally inert waste materials. They are produced in the largest volumes and do not pose a threat to human health. Their physical and/or chemical characteristics fail to satisfy all requirements for utilization in ordinary production. The aim of technology design is to work them into the building products with suitable utility properties. • easier workable waste materials containing toxic components are produced in large volumes. In spite of the content of toxic components, their physical and chemical properties make them suitable for ordinary production, provided that the harmful substances are immobilized by the chosen technology."

Jan 1, 2008

By Yongxiang Yang, Yanping Xiao, Robert G. Harskamp

"Stricter environmental regulations demand for safer treatment and disposal of incineratior fly ashes. So far no sound technology and processes are available for a sustainable and ecological treatment of the waste incineration ashes, and only partial treatment is practised for temporary and short-term solutions. New processes and technology need to be developed for comprehensive utilization and detoxification of the MSW (Municipal Solid Waste) incinerator residues. The objective of the current research is to better understand the behaviour of the environmental harmful elements during low or high temperature treatment, and to find an optimum route for an efficient processing of the incineration fly ash. In the present study, the fly ashes including boiler ash and ESP (Electrostatic Precipitator) ash sampled from a MSW incinerator were washed with warm water, and the residues were dried and sintered or vitrified at high temperatures. The solutions from ash washing were analysed, and will be treated for salt extraction and purification. The ash residues before and after thermal treatment were also analysed. The results of vitrification and thermal behaviour were compared with those from the ashes without pre-washing. It was found that water pre-washing is an efficient way to remove certain water-dissolvable volatile salts such as chlorides, and thus the secondary emissions during vitrification could be reduced. INTRODUCTION The air pollution control residues from MSW incineration are classified as harzardous waste, including boiler ash, ESP ash and filter cake. The boiler ash is the firstly settled flue dust in the dust-collecting equipment under the boiler, the ESP ash is collected by an electrostatic precipitator in the second step, finally the flue-gas is further cleaned by the wet-scrubbers and residues are accumulated in the filter cake. Both the boiler ash and ESP ash are classified as hazardous materials, harmful to the environment due to the high concentrations of environmental hazardous elements. However, due to the different locations of the ash collection, the boiler ash has different compositions compared to the ESP ash, and is considered less toxic. Fly ash is generally toxic and with low bulk density, and has to be treated before final disposal. The current industrial practice is normally the landfilling after partial detoxification such as cement solidification."

Jan 1, 2008

By Maribel L- Saucedo-Muñoz, Toshiyuki Hashida, Victor M. Lopez-Hirata, Shin-Ichi Komazaki

"Small-punch tests were conducted at 4, 77 and 293 K on three types of austenitic stainless steels JNl, JJl and JK2, which were solution treated, water-quenched and then aged at 923, 973, 1023 and 1073 K for 5 h. Small-punch test energy was employed for the evaluation of the aginginduced embrittlement behavior in these materials. Fracture surface of small punch test specimen for the solution treated steels exhibited a ductile fracture, showing the highest SP test energy values. The presence of intergranular brittle fracture was observed in aged specimens. Smallpunch test energy decreased significantly as the aging process progressed. The highest and lowest decrease in small-punch test energy with aging temperature occurred in JNl and JK2 steels, respectively. The decrease in small-punch test energy showed to examine appropriately the aging-induced embrittlement in these materials. The difference in aging-induced embrittlement behavior for these steels was explained based on the volume fraction of intergranular precipitates in aged samples.IntroductionA high level combination of strength and toughness is required for cryogenic structural materials used in the superconducting magnets of fusion nuclear reactor. This requirement is beyond the capability of conventional austenitic stainless steels [1]. The Japan Atomic Energy Research Institute (JAERI) developed new cryogenic JNl, JJl and JK2 austenitic stainless steels. The structure of superconducting magnets is supposed to be constructed by welding thick plates of this kind of steels. Thus, most of the components are exposed to thermal cycles. The slow cooling may cause microstructure changes in both the base material and weld zone. These changes may also decrease the fracture toughness of these materials at cryogenic temperatures. Therefore, it is important to study the effect of thermal aging on fracture toughness behavior for these steels. Konosu et al. [2] carried out a study of the effect of thermal aging on the mechanical properties for JNl steel using tension and fatigue tests. Kwon et al. [3] evaluated the deterioration in fracture toughness at cryogenic temperatures for the isothermally aged JNl steel by means of the Small-Punch (SP) test. No other reports were found about the cryogenic fracture toughness behavior for this kind of steels. To evaluate the cryogenic fracture behavior, the elastic-plastic Jrc value is a good alternative [4,5]; nevertheless, the standard required specimen size makes it difficult to be used for the fracture toughness evaluation in small zones."

Jan 1, 2011

By William J. Mallio

Substantial differences between in situ and conventional technology require that in situ ore grade be established for deposit as distinct from the total contained metal value. Establishing an in situ ore grade involves determining the fraction' of the contained metal that can be leached by the fluid. This depends on the proportion of the ore minerals that occur on fluid flow paths as defined by the permeability distribution. Mechanisms involved in the in situ mining of sulfides are: oxidation of the sulfur, solution of the metals, complexing of the released metals, and a transport to a recovery point. Metal ions may be delayed or lost due to inefficiencies in these pro-cess steps or by reactions of the metal ions in solution with the rock. These reactions can involve precipitation of new phases, exchange of the metals of the interest with Ca or Na in clays or zeolites, retention of metals in oxidized mineral grains, or secondary enrichment of other sulfides along the paths of the solution flow. The efficiency of solution of metals and potential loss or delay mechanisms are controlled by local equilibria (the Eh, pH conditions) present in different parts of the ore zone. Permeability distribution in the rock mass and the coincidence of ore minerais with flow channels must be determined before a deposit can be judged suitable for in situ mining. Laboratory studies indicate that the natural permeability system is dependent on the degree of cementation of veins by late generation hydrothermal activities. The major conclusions of the study are:, 1. Deposit selection is critical; suitable deposit types include deep lying sedimentary deposits, selected zones of porphyry systems and vein controlled hydrothermal deposits; 2. Adequate laboratory and geochemical analyses should be undertaken through quantitative petrographic study and permeability mapping; and 3. Economic incentives for in situ mining must consider limitations of recovery caused by inefficiencies in dissolution and transport associated with particular deposits.

Jan 1, 1981