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By Alpagut Kara

Turkey is the fifth biggest ceramic tile exporter in the world. Considering the expectation that the Turkish tile sector continues to expand, further studies both on the improvement and the development of tile formulations are necessary in order to make the producers advantaged in the world market while maintaining the capital and running costs at reasonably competitive levels as well. In addition to such studies, waste management in tile manufacturing has also recently become an important issue. Accordingly, the industrial use of wastes in the traditional ceramic industry has been intensively investigated in the recent years. This work describes part of a detailed research project carried out jointly on the possible re-use of muds (raw production waste) from glazing and pressing lines of a local tile company in the development of new wall and floor tile formulations. In order to achieve this, the waste material was firstly investigated in function of chemical and mineralogical compositions. Then, the particular focus was given to the presence of the waste material in increasing amounts on the thermal behaviour and physico-mechanical properties of the re-formulated tile bodies. During the studies, SEM in combination with EDS, and thermal analysis techniques such as non-contact dilatometry were widely employed. The results indicated that it was possible to use the waste materials in the commercial tile production without deteriorating the relevant technological properties.

Jan 1, 2006

By Gordon Holcomb, George R. St. Pierre, Robert A. Rapp

Carbon/Carbon composites offer promise as high-temperature structural materials. A primary limitation on their application is the need to provide protection against oxidation in hot oxidizing environments. Silicon carbide conversion coatings have been shown to provide extended protection at temperatures of 1600°C. SiC coated C/C components have been used in several aerospace applications. In the present paper, the preparation of carbon fibers and their treatment during subsequent processing into coated components are discussed with particular emphasis on the processing variables that can result in improved oxidation resistance. In particular, the influence of substrate inhibitors and selective sealants for cracks in coated C/C components are analysed.

Jan 1, 1988

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified.

Jan 1, 2006

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified.

Jan 1, 2006

By Z. R. Llanos, W. G. Deering

Gulf Chemical and Metallurgical Corporation (GCMC) has been operating facility for treatment of spent catalysts in Freeport, Texas since 1974. Recently, GCMC expanded its operations with the addition of an electric furnace for the production of fused alumina and mixed alloys. GCMC and its affiliate Sadaci, started up a new pre-treatment facility in Ghent, Belgium in 1998. GCMC is also part owner of Bear Metallurgical Corporation, a major producer of ferroalloys in the United States. This paper reviews the processes at these facilities. Changes in the management of hydrotreating and hydrorefining spent catalysts are discussed in light of recently issued federal regulations that made the majority of spent catalysts a listed hazardous waste.

Jan 1, 2000

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified.

Jan 1, 2006

By Keith Axler

The high reactivity of plutonium metal presents safety concerns related to material containment during fire scenarios. Plutonium metal is liquid at temperatures achieved under selected fire scenarios. The appearance of liquid plutonium challenges the corrosion resistance of the containment materials. However, by the in situ formation of intermetallic compounds, the plutonium metal can be stabilized as solid and the integrity of the containment vessels preserved. Studies have been conducted to demonstrate candidate materials, including lead, which can be introduced to the liquid-plutonium system and bind the corrosive liquid metal through the formation of intermetallic phases. The results of these investigations will be presented along with a discussion of the experimentally determined phase behavior for the plutonium-lead system.

Jan 1, 1995

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified

Jan 1, 2006

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified.

Jan 1, 2006

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified.

Jan 1, 2006

By Lucas Barbosa de Souza Martins, Frederico Muylaert Margem, Nathalia Carneiro Garcia Rosa, Sergio Neves Monteiro

"A natural banana fiber extracted from the plant pseudostem has shown values of density and mechanical strength with potential for uses in engineering applications such as automobile interior parts and floating components. Moreover, natural fibers can also be used as insulating materials in packaging and building panels. In this case some thermal properties are required. Therefore, the objective of this work was to evaluate the thermal behavior of the banana fiber by means of TGA, DTG and DSC analysis. The TGA curves revealed weight loss related to release of humidity and molecular structure decomposition. Peaks in the DTG curves indicated two intervals in temperature associated with different decomposition processes. The only endothermic DSC peak found was attributed to the lignocellulosic water of hydration being lost around 121°C.IntroductionIn recent times, environmental aspects related not only to pollution caused by non-degradable synthetic leftovers, specially polymeric wastes, but also to climate changes as a consequence of industrial activities, are motivating the use of natural materials. A particular case is fibrous composites, like the fiber grass composites. These synthetic materials, made from non-renewable polymers, are practically non-degradable and contribute to global warming by the CO2 emission associated with the energy required for the fabrication process. In spite of these environmental shortcomings, fiber materials are essential for the production of many items such as insulating chests, automobile cushion, construction panels, etc. An environmentally correct alternative to replace synthetic fibers composites is the naturally existing ones extracted from plants such as ramie and sisal. These have some environmental advantages of being renewable and degradable, these banana plant provide a negative contribution to C02 emission by absorbing greenhouse gas during the plant life cycle. Banana fibers have been used since long time in simple items such as ropes and rugs. Today they are used in engineering applications related insulation in building panels [2] and finish parts in automobile interior components [3]."

Jan 1, 2012

By V. K. Kalyani

The present paper discusses a three layer feed forward artificial neural network (ANN) model, trained using the error back propagation algorithm, has been established to simulate the column flotation circuit used for beneficiation of Sillimanite. Parameters such as superficial air velocity, wash water rate, froth height, % solid, feed velocity, sodium silicate and oleic cid are considered as process operating variables and % yield of Sillimanite is the output of the experiment. The results from the ANN modeling, involving the non linear relationship between inputs and outputs, indicate good agreement with experimental observations. The network model validates the experimentally observed trends. The optimal model parameters in terms of network weights have been estimated and can be used for computing parameters of the process over wide-ranging experimental conditions.

Jan 1, 2006

By Ronald J. McGregor

An overview or precious metals project development and start-up, which emphasizes the process decision. Logic which determines process flowsheet, project economics, and training required to train new operators for start-up. The process decision required to successfully develop a precious metals project requires a blending of test data, environmental considerations and operations experience. Decisions to use Merrill-Crowe or carbon adsorption/ electrowinning/replating, fixed pad or multi-use pad {in heap leach) are dependent not only on technology but also on ability to train new operators. The market for experienced operators is acutely depleted and almost all new operators will have to be "home grown". Experience from the Brewer project in South Carolina as well as other projects put together in the West will be discussed.

Jan 1, 1989

By He De-wen

The influence of coal desulphurization by fungus was experimentally studied. The present results suggest that fungus can effectively remove inorganic and organic sulfur in coal. The main factors that influence the desulphurization by fungus such as pH value, temperature, coal slurry concentration and coal granularity are studied by orthodox experiment and the optimal experimental conditions are as follows: pH value 6, temperature 45 C, coal slurry concentration 10% and coal granularity 100 m. Under the above conditions, fungus can remove up to 44.96 total sulfur and 54.87 inorganic sulfur within two days and their desulphurization rates will increase along with time. Compared to sulfolobas, desulphurization by fungus is steady and more effective and has the advantage of high speed.

Jan 1, 2006

By D. N. Wilson

The potential risks of working with lead have been recognised for centuries, but it is only with the development of sensitive measuring techniques in relatively recent years that it has been possible to establish effective approaches for the monitoring and control of lead exposure. This paper examines the principal control measures employed today - lead in air and lead in blood - and reviews the evolution of numerical standards, with particular reference to the latest understanding of health effects. In addition to lead, a large number of other metals are commonly encountered when producing lead and zinc - both primary and secondary - and the health effects of many of these are discussed. Modern hygiene practices and technologies, which have proved successful in reducing worker exposures, are reviewed. The paper concludes with a look at how exposure standards are likely to change in the near to medium future

Jan 1, 2000

By Chang-hong Peng

Solubility phase equilibrium in the ternary system of Me2+-NH4+-SO42--H2O (Me2+ represented Mn2+, Zn2+ and Fe2+) was studied by the isothermal method at 298K and physicochemical properties of the saturated solution such as density, refractive index and pH were also investigated. The experimental results show that the solubility isothermal phase diagrams of these systems consist of three invariant branches, two invariant points and three crystallization fields. Corresponding to the three crystallization fields, there have three phases of solid, that is MeSO4?nH2O, (NH4)2SO4 and (NH4)2Me(SO4)2?6H2O, respectively. At the eutectic point, the concentration and the refractive indexes of the saturated solution change evidently. Otherwise, the pH value change slowly in all the systems. The calculated results of the density and refractive index agree with the experimental results.

Jan 1, 2006

By Hirokazu Narita

The extractability for Pd(II) using MOTDA and DHS and their durability against a mixed solution of HNO3 and HCl was investigated by solvent extraction and FT-IR measurements. Both MOTDA and DHS selectively extracted Pd(II) over Pt(IV) from 0.75 M HNO32.25 M HCl solutions. The extraction rate of Pd(II) with MOTDA was much greater than that with DHS. In the durability test, the extraction percentage of Pd(II) and the FT-IR spectra were measured using MOTDA and DHS after stirring with 0.75 M HNO32.25 M HCl solutions. The extraction percentage of Pd(II) with MOTDA hardly changed during the two-month stirring; however, that with DHS decreased with an increase in the stirring time. The FT-IR spectra showed the sulfoxide formation by the oxidation of the sulfide in DHS, but not in MOTDA. Consequently, it was found that MOTDA is more durable than DHS.

Jan 1, 2006

Iron(II), sulphur dioxide and sugars such as lactose are potential reducing agents for manganese dioxide to produce manganese(II) for subsequent hydrometallurgical treatment. The leaching of limonitic laterite and manganiferrous ores with sulphur dioxide produces iron(II) which in turn can catalyse the leaching of manganese dioxide in acid media. This paper presents a critical analysis of the kinetics of reductive dissolution of synthetic manganese dioxide and manganese ore to compare and contrast the effect of sulphur dioxide and iron(II) in acid media containing sulphate or perchlorate anions. Both one-electron and two-electron mechanisms are considered in the case of sulphur dioxide. The current knowledge on chemical speciation is used to construct an Eh-pH diagram to show the effect of complexation of Mn(II), Fe(II) and Fe(III) with sulphate. Heterogeneous and electrochemical reaction kinetic models are combined to propose reaction mechanisms which rationalize the dissolution kinetics.

Jan 1, 2003

By V. M. Mukhin

Among the methods proposed for spent activated carbon regeneration, the most acceptable is, thermal reactivation, because in this case the existing equipment for manufacture of activated carbon can be adapted for this purpose. In order to conduct the process of thermal re-activation of spent activated carbon directly at gold mills, a full-scale drum-type furnace with external electric heating has been developed, i.e. EPV-300 model with a throughput rate of 50 to 120 kg/hour. Its use ensures restoration of the adsorption properties of carbon up to the level of fresh activated carbon with an insignificant (by 0.7%) decrease in strength and with a high (95% to 97%) yield of reactivated carbon. During the recent years, activated powder carbon has been extensively used in flotation processes for treating polymetallic ores at ore treating plants to improve recoveries of main metals (copper, lead, nickel, etc.). Especially large volumes of activated powder carbon are used at the Talnakh concentrator of the Norilsk Mining and Metallurgical Complex in Russia for absorption of residual flotation reagents from recycled water in order to ensure efficient selective separation of minerals with similar physical and chemical properties.

Jan 1, 2006

By Dan Adams

A number of gas-liquid processes require high intensity agitation systems to provide uniform blending and dispersion of reactants in order to achieve desired end products. Processes such as hydrogenation, fermentation, and minerals processing have used conventional down pumping or radial agitation systems with some success. In 1996, LIGHTNIN introduced the concept of Up-Pumping to the industrial marketplace as an improved mixing technology for these applications. For processes requiring gas-liquid mass transfer, such as those listed above, conventional mixing technology requires the use of gas introduction devices (sparges) below impellers. These devices can be a maintenance concern due to plugging and erosion in the presence of solids. Up-Pumping impeller systems are able to draw in a significant amount of gas from the headspace, much more so than conventional vortexing impellers designed for headspace gas incorporation. This paper will demonstrate the effectiveness of Up-Pumping impeller systems that have the potential to eliminate need for sparge devices entirely. It demonstrates the ability of Up-Pumpers to re-entrain gas for higher utilization compared with conventional impeller technology. This is significant in applications using costly gases such as enriched oxygen or hydrogen, reducing overall operating costs of production.

Jan 1, 2003