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By Payal Bakshi, Sangeeta Tiwari, Mohini Saxena, Anusha Sharma

"Recycling and reuse is perhaps the most favorable and beneficial way to solve the problem of industrial waste disposal. However, the use of industrial wastes like fly ash, tailings etc is in practice for brick manufacturing, land filling, embankments filling etc. These existing practices do not add enough value to the wastes. Moreover, some wastes may have very good potential to be incorporated in valuable products like paints. This study reveals about the value addition of industrial wastes like fly ash, copper tailing and blue dust as an extender in paints. Comparative properties and characteristics of these three wastes for application in paints are discussed. Fly ash, copper tailing and blue dust were characterized for physical, chemical and mineralogical properties and used in different paint formulation based on their potential to the particular application. Fly ash has been found very useful in enamel, primers and flat paints while copper tailing was found suitable in oil based paint formulations. The performance of fly ash and copper tailing paints were evaluated by comparing with those of conventional whiting extender. Blue dust was compared with conventional iron oxide for use in priming coats. The extender properties of these new material and paints prepared out of blue dust, fly ash, copper tailing, were found better than the existing related materials.IntroductionIndustrial development and environmental reforms should run parallel to benefit each other. This is the best policy, which must be adopted by industries for the sustainability of the current modern life. The high degree of industrialization and urbanization adds scads of waste resulting problem of pollution and challenges of their safe disposal. The nature of waste depends on the process that produces waste as its by-product. Therefore, policies/plans are prepared by keeping the view of possible potential hazards. Among the different wastes some are generated in the industries, which have great importance in the country’s economy, like fly ash waste from thermal power industry and mining waste. In India the total contribution of thermal power in the total electricity generation is more than 70% and it produces about 123 million ton of the fly ash annually [1]. On the other hand mining plus extraction of ferrous and nonferrous metals also produce waste in million tonnes of categories [2]. Since the generation of this waste is very high they cover large land area for their disposal and dumping [3]. The storage of this waste in the dumping sites for long time duration may cause problem of land, surface water, ground water and fertile soil contamination [4]. As far as Indian fly ash is concerned it does not contain toxic element over the limits of hazardous waste [5]. However, in general most of the metals deposits are found in the form of pyrite based ores. Mining wastes contain toxic elements e.g. heavy metals in varying amount, which get mobilized when pyrite get oxidized to sulphate producing sulphuric acid [6,7]. These ores contain very less amount of targeted metals in themselves thus they require extensive preprocesses for concentration of the metals [8]."

Jan 1, 2008

By Helena Byrdziak

KGHM Polska Miedz S.A. is a significant European copper producer with production of 447,000 mtpy, operating three underground mines and three smelters. The company has been involved for years in environmental activity, which was stimulated not only by the company itself, but by the development of environmental regulations as well. The first set of regulations, concerning water protection, was' established in Poland' in 1974, while a comprehensive environmental law was passed in 1980. This law in general requires industry to submit all data of environmental significance to the local authorities. Based on this data, they establish limits concerning emissions into the air, water and ground, the amount of wastes produced and the means of their disposal. A company has to pay fees for each tonne of emitted substances and stored wastes. When the emission of a substance exceeds the limit, the company has to pay a penalty which is about ten times higher than the fees. This approach in general is effective because it forces companies toward: reduction of their emissions. The problem is that the law is constantly subject to change and is becoming not only more restrictive but is involving more and more bureaucracy.

Jan 1, 1999

By Peter Forschner

Classical Mixing Theory is based on applying many fundamental correlations to standard baffled dished bottomed vertical cylindrical vessels with high degrees of symmetry. Horizontal autoclaves operating at elevated temperatures and pressures have been used for more than two decades. All compartments and especially the first and last compartments are asymmetrical. To date no comparison of the effects of the asymmetric geometry on mixing system design and scale-up has been published. The results of investigating solids suspension, mixing time, momentum transfer from the impeller to feed slurry and feed inlet location in the first autoclave compartment are presented as influences on residence time distribution. CFD modeling was developed and verified with the test apparatus.

Jan 1, 2003

By K. Noda

Tamano Smelter of Hibi Kyodo Smelting Co., Ltd. is carrying out a low cost production using a Tamano Type Flash Smelting Furnace (T-FSF), which is an improved version of Outokumpu Type Flash Smelting Furnace but without slag cleaning furnace and also by developing its own coke combustion technology. Coke combustion technology that is the basis of the system has been improved several times and, at present, it has evolved to a stage where it can be reproduced on the Computer guided system for Coke Combustion in the T-FSF (CCCT) using a general- purpose computer. This CCCT is featured by 'its trend control and predicting function, and an operator can freely control the operation parameters so as to control the operation flexibly. We have recently developed an overall energy reduction system covering the Smelting Plant to Sulfuric Acid Plant, which we call an Optimum Low Cost Operation System (OLCO) to reconsider the energy costs including coke, heavy fuel oil, and electric power. In this report, we would like to present the recent operation of T-FSF based on CCCT as well as the optimum energy operation utilizing OLCO system.

Jan 1, 2002

By Catherine Williams-Beam

Thallium is more toxic to humans than mercury, cadmium, lead, copper or zinc. Its chemical behavior resembles the alkali metals (K, Rb, Cs). It occurs almost exclusively in natural waters the monovalent thallous cation. The solubilities of thallous compounds are relatively high so that monovalent thallium is readily transported through aqueous routes into the environment. The major sources of thallium are the base metal sulfides and precious metal bearing sulfides. Therefore, it is often present as a contaminant constituent in waters emanating from heavy metal sulfide bearing deposits. Thallium can be effectively removed from wastewater to <2 µg/L by reductive precipitation of thallium sulfide. Effective thallium sulfide precipitation requires a controlled solution potential/pH combination. The required potential can be effectively achieved by utilizing a particulate iron slurry or packed column environment. Experimental results will be presented and discussed.

Jan 1, 2003

By Fashina Olugbenga Emmanuel, Ghazali Akeem, Adegbola Adekunle Amos, Omotoyinbo Joseph Ajibade, Olaniran Oladayo

"Modern engineering materials are required to be light weight and corrosion resistant, coupled with high strength and hardness. In this work, Al formed the parent metal and alloyed with 2.03% of Copper by sand casting process. The cast product 2024 was warm worked at various temperatures ranging from 300 to 5600c at 5%, 10%, 15% and 20% deformation respectively and aged accordingly. The results showed that the mechanical properties vis-à-vis hardness, tensile improved with increasing % deformation at a higher temperature. This was due to the progressive close-up of the voids emanated from casting by increasing deformation which is evident from the micrographs. MATLAB was also adopted to generate a model capable of determining the trend of flow of stress at operating temperatures. This was of immense value due to an increasing impact at higher percentage deformation with temperatures. Hence, Al -alloys will find applications in land vehicles, ships, trains, and aircraft, at elevated temperature.INTRODUCTIONThe problem of safe vehicle design with maximum impact energy absorption is a significant subject in structural crash worthiness design [1]. All engineering designs are expected to ensure the safety of users' life. This informed several studies meant to probe the causes of component failures in equipment, vehicles, and aerospace design and decide on appropriate solutions through materials selection techniques. A common example is in the design of crankcases and heads, piston, and cylinder blocks. As with engine blocks, cylinder heads can be made of Cast Iron or Aluminium Alloy. A head made of Aluminium alloy is lighter in weight than if it were made of Cast iron [2]."

Jan 1, 2013

By Wen-Ming Chien, Vamsi Krishna Kamisetty, Amrita Mishra, Ivan Gantan, Prathyusha Mekala, Dhanesh Chandra

"The phase equilibrium and characterization studies by using high temperature X-ray diffraction (XRD) and differential scanning calorimetric (DSC) methods have been performed for binary organic thermal energy storage materials. The organic thermal energy storage materials undergo a solid-solid state phase transition before melting which stores large amounts of thermal energy. Two materials [tris(hydroxymethyl)aminomethane(TRIS) and 2-Amino-2-methyl-l, 3- propanediol(AMPL)] were used for this study. Binary samples of AMPL-TRIS were prepared to perform high temperature XRD characterization and DSC studies and the binary AMPL-TRIS phase diagram was developed. The high temperature solid-state phases of AMPL and TRIS were characterized as a disordered BCC structure. It was found there is virtually no solubility of TRIS in AMPL or vice versa below -75 °C. The maximum solubility of TRIS in AMPL is 11% TRIS at 75 °C. The eutectoid transformation was shown at 19%TRIS-81%AMPL composition and at a temperature of 75°C. Lattice expansion calculations on single phase of TRIS and AMPL have been performed.IntroductionThermal energy storage materials can store a large amount of heat due to the presence of thermal transitions from the orientationally ordered to disordered phases occurring before melting. These molecules (such as amine and alcohol derivatives of neopentane) can reorient as a whole about the central carbon atom to form orientationally disordered crystals (ODIC) and their spherical shape makes them reorient relatively easier. Thermal energy storage materials are becoming increasingly important as a renewable energy resource. These molecules undergo large changes in enthalpies at solid-solid transitions. The presence of these compounds with large enthalpy changes are identified as potential thermal energy materials and some of die applications are solar cell systems [1-3]. Binary mixtures have been found as a way to adjust the transition properties in addition to pure compounds [4]. Tris(hydroxyrnethyl)aminomethane (TRIS, C(CH2OH)3NH2) and AMPL, CH3C(CH2OH)2NH2) are two important thermal energy storage materials."

Jan 1, 2012

Lance based copper-nickel matte converters have become an established technology in the field of base metal sulphide smelting and converting. An Ausmmelt® converter is currently being constructed at Anglo Platinum in South Africa to convert a nickel-copper rich matte containing platinum group metals (PGM&apos;s). The accurate prediction of the matte chemistry is required to control the composition at the endpoint which influences segregation of PGM&apos;s during the subsequent slow cooling and magnetic separation processes. A hybrid modelling approach is introduced in this paper that incorporates both the effect of thermochemistry and system dynamics. It will be shown how the model relates to fundamental conservation laws, while still providing enough flexibility to adapt to changing operating conditions. It will also show how off-line modelling can be incorporated into a robust on-line model. Based on the data from many pilot plant trials, the model prediction performance is shown to be within the accuracy requirement set by industry and therefore constitutes a reliable basis for model based control. The final generic model structure takes on the form of an thermodynamically integrated ARMAX hybrid model. The final model has the advantages of being dynamic, adaptive, robust and it can be related to thermochemical fundamentals.

Jan 1, 2002

By A. Ohno

"A new near net shape casting process, OHNO Continuous Casting (OCC), has been recently developed. In this process, molten metal is fed into a heated mold maintained at a temperature above the solidification temperature of the metal being cast. Solidification begins from the central core of the casting rather than the wall of the mold. With the heated mold, the formation of crystals on the mold wall is prevented and solidification occurs out of contact with the mold surface. This produces near net shaped products with smooth, mirror-like surfaces and unidirectional grain structures free from cavities, porosity and segregation. Any crystals formed at the beginning of solidification decrease in number as solidification progresses and eventually a single crystal product is obtained. This process is applicable to any metal alloys, converting them into new materials with superior properties and quality.IntroductionAs a result of growing technical demands for more advanced and diversified materials, the OHNO Continuous Casting (OCC) technology has found many new applications in industry. Considerable interest in the process has been shown in Japan and other countries because of its distinct ability to:produce a single crystal, (1)produce a remarkably clean cast surface without a witness mark,provide extremely good ductility,and reduce casting defects and segregation.This paper provides an overview of the principle of the OCC process and describes the remarkable characteristics of the material produced by this method."

Jan 1, 1988

By M. K. Alam

Chemical Vapor Deposition (CVD) processes are currently attracting special attention in materials processing. CVD processes are now used to produce special materials in the form of thin films, coatings, composites, and optical fibers. This process produces material of high purity, in complex shapes, and in a variety of microstructures. It is a capital intensive process, involving use of high cost raw materials. Modeling simulations have the potential of reducing the time for CVD . process design, and the need for experimentation. Modeling would, therefore, appear to be an attractive option for producing a product of acceptable quality. At Ohio University, progress has been made in modeling of CVD processes, specially in the areas of optical fiber preform fabrication, and fiber coating.

Jan 1, 1990

By G. T. Lapidus, O. J. Solis-Marcial

"The oxidative dissolution of copper from refractory minerals, such as chalcopynte, represents a technological challenge that has occupied hydrometallurgists for more than half a century. Innumerable processes have been suggested, but the majority operates at high temperatures or employs corrosive media. The origin of this refractory nature is the formation of passivating phases of iron(III) or copper. One option is to add non-corrosive ligands that complex these metal ions, thereby facilitating their dissolution. In the present work, the effect of acetone in sulfuric acid solutions was studied. The initial experiments were on chalcopynte carbon paste electrodes using cyclic voltammetry, where greater reactivity was observed. Later, leaching tests with hydrogen peroxide, cupric sulfate and ozone and, as oxidants, were performed. High extractions were achieved in three hours at 50°C. The solid residues contained the iron in the form of Fe203 and FeOOH.IntroductionChalcopyrite is the most important mineral of polysulfide copper ores [1] and accounts for approximately 70% of the world's copper reserves [2]. Currently, the copper present in chalcopyrite is extracted mainly by pyrometallurgical processes, which generate environmental concerns because of the formation of SO2 gas and submicron particulates [3]. The development of a less aggressive hydrometallurgical process for the extraction of copper would constitute a possible solution to these problems. For that reason, studies of the dissolution behavior of chalcopyrite are of great technological importance [4], However, the proposed oxidative leaching routes for chalcopyrite, generally at high pressures and temperatures, have not been implemented on an industrial scale, because of the elevated costs required to equal the high copper extractions obtained in thermal processes. These extreme leaching conditions are required because of the refractory nature of chalcopyrite. Passivation has been used to explain this phenomenon, although researchers have disagreed on the composition of the layer, which is various have assumed to be sulfur, copper sulfides, and iron-bearing jarosites or hydroxides [5]. If the latter compounds are the cause, an alternative solution would be the use of polar organic solvents in the oxidative leach to decrease the formation of the passivating iron layer. In this work, the influence of acetone on the oxidative leaching of a chalcopyrite concentrate at room conditions is explored."

Jan 1, 2012

By Shun Fujieda, Shigeru Suzuki, Kozo Shinoda, Tetsuo Fujita

"Dowa Metals & Mining Co. Ltd. has developed and plant-practiced a unique scorodite synthesis technology (DMSP®) for arsenic immobilization by oxidizing Fe(ll) ions in the presence of As(V) ions. Dowa has improved the DMSP® technology and has developed the process extensively for other applications. This paper focuses on the applicability of the DMSP® for various cases of copper smelting, and introduces other technologies for fixing arsenic and recycling gallium from GaAs, simultaneously processing (fixing) arsenic and thallium, and fixing and recovering arsenic from dilute arsenic solutions. The DMSP® was found to be applicable not only for various processes in nonferrous smelting, but also for other applications with a high potential for reducing environmental problems.IntroductionDowa Metals & Mining Co. Ltd. developed a method for synthesizing scorodite at ambient pressure [1], The scorodite is precipitated by oxidizing Fe(II) ion in a high-concentration As(V) solution. The scorodite produced in this way does not readily release arsenic because of its high crystallinity. Dowa built a demonstration plant for this technology at the Kosaka Smelter and established the production of scorodite at 30 t As/month by treating intermediate products from copper smelting as the starting material. The DMSP® was demonstrated to be favorably applicable to copper smelting [2]. We are engaged in further increasing the amount of arsenic fixation by the use of this process. Further improvements in productivity, cost reduction and applicability in various processes have been devised. Dowa has been endeavoring to resolve other problems as well as to improve productivity. We have gained extensive knowledge on arsenic treatment in our endeavors, enabling us to solve problems and improve productivity. This paper introduces the investigations and developments related to DMSP®."

Jan 1, 2012

By V. K. Handa

Sterlite Industries (I) Ltd. started its copper smelter in 1996 and worked through the common problems associated with smelter start-ups. Specific issues in the converter area included converter blower IGV problems, punching machine reliability, converter spitting, back collar burning, ,and short converter campaign life. With a very young and dedicated team of engineers and technicians, smelter management assigned teams of three to four members to work scientifically and systematically through each major problem area to recommend and implement appropriate solutions. The converter mouth was redesigned with respect to tuyere and metal height to eliminate spitting and back collar burning. The air line was changed in places to reduce the pressure drop. A new back-up compressed air line and vessel was installed to prevent tuyere blockage in the event of a blower trip or power failure. The converter mouth liners and bricking around the mouth was modified to eliminate metal leaking through the pouring lip Modifications to the punching machines were made to address specific problems and preventative maintenance practices were further streamlined and reinforced to ensure 100% availability of hot metal cranes, converter blowers, punching machines, and ID fans. Matte availability and matte temperatures were improved by streamlining the upstream ISA and Rotary Holding furnace areas. Implementation of a detailed training program for the converter operators significantly improved the operation and morale. Water-cooled double hoods and a third converter were installed as part of the smelter modernization plan. The new hoods dramatically improved hygiene in the crane aisle while the addition of the third converter posed new challenges for the same motivated group of crews with respect to flip flop operation to keep the idle converter hot and to maximize in-stack time, managing crane/ladle logistics, and managing revert generation. This paper describes the converter operation&apos;s journey from the initial days of long blowing times and large revert accumulations to present operations with two converter flip flop operation, and also describes the team work, constant focus on increasing productivity and reducing costs, and benchmarking.

Jan 1, 2002

By Jian Li, J. Miles, P. Liu, W. Cook, W. Zheng, Alvin Qian

"High temperature corrosion resistance is one of the key challenges in water-cooled nuclear reactor material development. Iron based materials with low Cr content exhibits superior high temperature mechanical properties. However, due to the relatively low Cr content, their corrosion resistances under supercritical water (SCW) conditions are generally poor. High-Cr alloys, despite their much improved corrosion resistance, often suffer from embitterment due to the precipitation of sigma phase in the microstructure. In this study, corrosion resistance of an in-house produced high Cr steel (25%Cr) showed much better corrosion resistance compared to that of low Cr alloy (14%Cr). This high-Cr steel can potentially be used as a corrosion-resistant coating for structural materials in sew applications.INTRODUCTIONThe supercritical water-cooled reactor (SCWR) concept is one of the promising designs for the next generation nuclear reactor, in which the water coolant is designed to be at about 625°C and 25 MPa at the outlet of the reactor core. Under these relatively high-temperature and high-pressure conditions, the cooling water is at supercritical state. High-temperature mechanical properties, corrosion resistance and radiation damage are some of the key challenges. At present, no single commercial material can meet all the requirements of the severe SCWR in-core conditions. Canada supports research in several key areas of SCWR development, including materials selection. A major focus is on materials development, selection and evaluation for both in-core and out-of-core components.Allen et. al. [1] carried out a comprehensive study on the SCW corrosion resistance up to 600 °C on commercially available high temperature materials including Ni-based super alloys, various types of stainless steels and ferritic/matensitic steels. They concluded that ferritic steels develop a relatively thick but mechanically stable oxide layer, while austenitic alloys develop a thinner oxide layer that has been found to spall in some cases. Of the three types of alloys examined, the Ni-based alloys exhibited the lowest oxide thickness, however pitting was observed in the vicinity of intermetallic precipitates."

Jan 1, 2011

By Hongmin Zhu, Guihua Wang, Xiangsheng Wang

"The anode process of carbon electrode in fluoride melt was studied by voltammetry and chronoamperometry. Anode gases were analyzed by gas chromatography on-line during controlled-potential electrolysis. Two peaks were observed on the cyclic voltammograms. According to the results of gas chromatography, the first peak was corresponded to the discharge of residual oxide ions, with the formation of CO and CO2. Discharge of fluoride ions occurred at 4.1 V vs. Li+/Li, and leading to the anode effect. With the occurrence of anode effect, small amount of CF4 was detected. As the potential reached 4.5 V, CF4 and C2F6 gas evolution occurred, and the current increased to form the second peak.1.IntroductionIn the primary production of Aluminum and some rare earth metals like neodymium, a departure from normal cell operation known as anode effect results in the generation of perfluorocarbons (PFCs), which have high global warming potentials [1]. Owing to the pressure of environmental protection, considerable research has been carried out to clarify the mechanism of anode effect and PFC generation of industry and laboratory cells in the aluminum electrolysis system [2-9]. The common result on PFC generation is that the PFCs are emitted from Hall-Heroult cells only when they are on anode effect. In this article, we selected LiF, the main electrolyte for the neodymium electrolysis [10-11], to perform further investigation on the underlying kinetics of PFC generation and the nature of the reactions at the electrode.2. ExperimentalAll experiments were carried out in an alumina tube reactor, which was filled with high purity helium atmosphere. Spectrographic graphite crucibles were used, which played the dual role of molten fluoride container and the counter electrode. Lithium fluoride was analytical grade. The experiments were carried out at 900 °C."

Jan 1, 2011

By C. Segawa

SMM operates an original slime treatment process for recovering precious metals and other metals (Te,Se,Sb,Bi)from the copper and the lead anode tankhouse slimes. In recent years, the amount of slimes has increased and the pyrometallurgical processing units capacity became the bottleneck of the entire plants. For the expansion of the plant, new pyrometallurgical facilities, incorporating a BBOC, was commissioned in 1992 and has now been successfully operated. In addition, unit operations were optimized to increase recovery and reduce operating cost .. The results of modifications made in the plant are discussed in this paper.

Jan 1, 1996

By Lee Fergusson

"The primary features of ViroMine™ Technology are introduced and applications of ViroMine™ Technology to mine site remediation and the treatment of a variety of intractable waste-streams, including a technical discussion of acid neutralizing capacity, metals binding capacity and longterm stability of results. Outcomes from four applications at high-profile international mine sites are presented: 1) the superfund site at the Gilt Edge Mine, South Dakota, USA (four years of data on the treatment of acidity, TDS and metals such as Al, Co, Fe, Mn and Zn); 2) one of Australia’s most polluted sites at King River Delta in Tasmania (treatment of TAA and TPA, and metal and metalloid contaminants such as As, Cr and Hg); 3) The Aljustrel “Aqua Forte” mine site in Portugal (high acidity, metal and metalloid contaminants such as Al, As, Cu and Zn) and 4) the Ulsan Iron Ore Mine at Ulsan, South Korea (treatment of metal and metalloid contaminants such as As, Cd and Ni).IntroductionThe commercialisation of ViroMine™ Technology has resolved some of the most intractable pollution issues associated with historic mining ventures on a global scale and has facilitated the neutralisation of Acid Rock Drainage (ARD), remediation of acidic and metal contaminated impoundments (including tailings dams) and promoted revegetation on tailings deposits and waste rock dumps. ViroMine™ Technology also enables current mining ventures to manage effluent simply and efficiently to meet increasingly stringent environmental standards and is enabling the mining sector to reconceptualise the management of mine spoil. The abilities of ViroMine™ reagents to neutralise the actual and potential acidity of sulphidic mine spoil coupled with the ability to bind metal and metalloid contaminants into non-bio-available forms are the key features delivering environmental and economic benefits to the mining sector and the broader community. Results from four projects utilising ViroMine™ Technology are presented to highlight the suitability of ViroMine™ Technology to treat all forms sulphidic mining wastes. 37"

Jan 1, 2008

By Ana E. Bohé, Georgina De Micco, Gastón G. Fouga

"In this work the reaction between several manganese oxides and chlorine is investigated in the range of temperatures between 650 and 950ºC. The reaction path for the chlorination of MnO is established, which involves recrystallization of high valence manganese oxides (Mn3O4 and Mn2O3) followed by its chlorination. For this reason, to understand the reaction of MnO, the chlorination of Mn3O4 and Mn2O3 has also been studied. The starting temperature for the reaction of these oxides is determined by non isothermal thermogravimetric measurements. The effect of temperature is analyzed, under our experimental conditions the rate of reaction is mass transfer controlled. The activation energy for the volatilization of manganese chloride is obtained which is in good agreement with volatilization enthalpy of MnCl2.IntroductionMany oxide ores which have manganese in their composition undergo chlorination processes during the extraction of refractory metals such as Ti, Hf and Nb. Although several works related with chlorination of manganese oxides were reported, there is no information about the kinetics or mechanism of the manganese oxide chlorination reactions. Okahara et al. studied the chlorination of manganese oxides and established that they react easily above 250ºC. Furthermore, they observed that chlorination of high order oxides is more difficult when there is not a reducing agent [1]. Ivashentsev studied the chlorination of manganese oxides using Cl2(g), CO(g) + Cl2(g) and COCl2(g). He established that the reaction of MnO started at 130ºC with formation of MnCl2(s), he also observed recrystallization of manganese sexquioxide [2]. Finally, the chlorination of manganese nodules from the ocean was studied by Murthy and Reddy [3] with the aim of obtaining valuable metals such as Mn, Co, Ni and Cu. They studied the influence of several parameters like temperature, carbon percentage, particle size and chlorine flow rate in the extraction process."

Jan 1, 2008

By Feng Ningchuan, Guo Xueyi, Tian qinghua, Liang Sha

"In this study, copper adsorption by orange peel which was chemically treated with sodium hydroxide was investigated. The morphological and chemical characteristics of the adsorbent were evaluated by spectroscopy and N2-adsorption techniques. Equilibrium isotherms and kinetics were obtained and the effects of solutions pH, adsorbent concentrations and temperature were studied in batch experiments. Equilibrium was well described by Langmuir and Freundlich isotherms and kinetics was found to fit pseudo-second order type adsorptions kinetics. According to the Langmuir equation, the maximum adsorption capacities (qm) for Cu(II) was 50.25 mg·g-1 at pH 5.3. With the temperature increased from 16 to 60°C, copper removal decreased. The loaded adsorbent was regenerated using HCl solution and could be used repeatedly at five cycles with little loss of adsorption capacity. The results show additional chemical treatment of the adsorbent by NaOH, is favor of improving the adsorption capacity. Introduction Increased use of metals and chemicals in manufacture industries has resulted in generation of large quantities of effluent that contains high level of toxic heavy metals and it poses environmental-disposal problems due to its non-degradable, persistence nature and accumulation throughout the food chain [1, 2]. Copper is known to be a commonly used heavy metal. This metal, which found many useful applications in our life, is very harmful if charged into natural water resources and may pose finally a serious health hazard. Many methods, such as chemical precipitation, ion exchange, reverse osmosis and adsorption, etc., have been used for heavy metal ions removal from various aqueous solutions. In recent years, there has been considerable interests in use of biological materials including algae, bacteria, fungi, agricultural by-products and residues as adsorbents to remove toxic metals from aqueous solutions by adsorption [3-8]. Adsorption process has been extensively used to remove copper from aquatic medium using low cost adsorbents such as peanut husks [9], plant materials [10] and cellulose materials [11]. Among them, agricultural by-products and biomass are relatively cheap and show very high adsorption capacities. However, to apply untreated agricultural by-products as adsorbents has the disadvantages such as low adsorption capacity, high chemical oxygen demand (COD) and biological chemical demand (BOD) as well as total organic carbon (TOC), due to the release of soluble organic compounds contained in the plant materials such as lignin, tannin, pectin and cellulose, into the solutions [12-14]."

Jan 1, 2008

By June-Yong Eom, Jong-Jin Pak, Jung-Mock Jang, Min-Kyu Paek

The nitrogen solubility in liquid Mn-Si, Mn-Si-Fe, Mn-Si-C and Mn-Si-Fe-C alloys has been measured by the gas-liquid metal equilibration technique in the temperature range of 1673-1773 K. The additions of silicon, iron and carbon significantly decreased the nitrogen solubility in liquid manganese alloys. The experimental results were thermodynamically analyzed by the Wagner’s formalism to determine the first- and second-order interaction parameters of silicon, iron and carbon on nitrogen in liquid manganese. The thermodynamic parameters can be used to predict the nitrogen solubility in ferromanganese and silicomanganese alloy melts as functions of the melt composition and temperature at given nitrogen partial pressures.

Jan 1, 2014