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By Mohamad Omarei, S. M. Sadrameli

"The aim of this research work was to produce biodiesel (fatty acid methyl esters, FAME) from canola oil using KOH loaded on y-Al203 support as a heterogeneous catalyst. Different parameters such as effects of the molar ratio of methanol to oil, catalyst amount and reaction time on the yield were investigated. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were used for characterization of the catalysts. A biodiesel yield of 86.67% was obtained under catalyst preparation and transesterification conditions of calcinations temperature of 773 K, 4 h of reaction time at 338 K, and using 3.5 wt% catalysts and molar ratio of methanol/oil of 15:1. The leaching of potassium species in the spent catalyst was observed.1. IntroductionBiodiesel is an eco-friendly and alternative energy source for diesel engines that can be synthesized by transesterfication of vegetable oil or animal fat with alcohols [1 ]. There are four principal approaches to the synthesis of biodiesel involving the transesterification of the triglycerides of the plant oils and animal fats: base catalysis [2], acid catalysis [3-5], employing supercritical alcohol conditions [6] and enzyme catalysis [7]. The commonly used homogeneous catalysts are NaOH, KOH and their alkoxides. Homogeneous alkali-catalyzed transesterification is much faster than acidcatalyzed transesterfication [8]. However, a large amount of water is required to transfer the catalysts from the organic phase to a water phase after the reaction. Therefore, it is considerably more costly to separate the catalyst from the produced solution [9]. These disadvantages could be removed by use of a heterogeneous catalyst [10]. The use of heterogeneous catalysts eliminates the neutralization step, hence it results much easier to separate from liquid products. Also, they can be designed to give a higher activity and selectivity and to have longer catalyst lifetimes [11]. A large number of different heterogeneous catalysts have been synthesized for biodiesel production. For example, calcined Mg-Al hydrotalcites [12], zeolite and metal catalysts [13], metal oxides such as calcium oxide (CaO) [14], magnesium oxide (MgO) [15], zirconium oxide (Zr02) [16], and supported catalysts [17] have been investigated as heterogeneous catalysts. CaO and MgO are most frequently used heterogeneous catalysts for biodiesel production [18]. In this present work, we aimed at developing an efficient catalyst for transesterification of canola oil. We have prepared KOH/ Al203 by impregnation and applied to determine the optimum conditions for biodiesel production. Three different variables including reaction time , alcohol to oil molar ratio and catalyst loading with may influence the quality of the produced biodiesel were optimized. Moreover, SEM (scan electron microscope), XRD (X-ray diffraction) and XRF were used for characterization of the catalysts."

Jan 1, 2012

By William C. Spindler

Five industrial installations of large lead-acid battery energy storage systems in operation in the United States, West Germany and the 'Republic of South Africa will be described. One example is for a deep mine shaft in which air ventilation and personnel evacuation require the highest reliability for emergency power. The battery system is designed for additional cost-effective benefits of peak load lopping and reactive power control. Commercially available lead-acid batteries of the following types are in use1 traction, truck, submarine, high power, and gel. Electrode grids of both the calcium and antimony alloy types are used. Applications include deep and shallow cycling as well as float and intermittent use. The advantages of sealed lead-acid batteries in UPS (uninterruptible power source) systems are well established throughout the world, and such system suppliers could readily develop markets for industrial emergency and peak power lead-acid storage battery installations.

Jan 1, 1990

By T. Shimizu

In Japan, the emission standard of selenium in effluent was set at a maximum of20 mgll in Feb. '94 for the first time, and it is scheduled to be further decreased to a maximum of 0.1 mg/I from Feb. '97 due to tightening of the Water Pollution Prevention Act. Selenium (IV) and (VI) are generally found in effluent from precious metals refineries. Although selenium (IV) can be easily eliminated by some reducing agents, selenium (VI) is more difficult to be reduced. Therefore, many smelters are having difficulty in complying with the new emission standard. At Mitsubishi Materials' Naoshima smelter, the behavior and the elimination of selenium in effluent have been extensively investigated. As a result, it was found that two strategies were particularly effective. One of them is improving the overall operation of precious metals refinery, that is, feeding uniformly the effluent to the waste-water treatment plant, reducing the effluent volume by recycling and recovering more selenium (IV) in the effluent. The other is eliminating selenium (VI) in the effluent from the precious metals refinery. It was found that selenium (VI) can be effectively reduced by using hydrazine under high? sulphuric acid concentration and high temperature conditions. By using these measures, it is considered that Naoshima Smelter will be able to comply with the new emission standard.

Jan 1, 1996

By M. Friák, L. G. Wang, M. Šob, V. Vitek

"The paper gives an account of applications of quantum-mechanical (first-principles) electronic structure calculations to the problem of theoretical tensile strength in metals and intermetallics. First, we briefly describe the way of simulating the tensile test and the electronic structure calculational method. Our approach is then illustrated on calculations of theoretical tensile strength in W, NiAl and transition metal disilicides MoSi2 and WSi2 with C11b structure. In Wand NiAl, we consider uniaxial tension along [001] and [111] directions. Although tungsten is elastically nearly isotropic (C44 = C”), theoretical tensile strength exhibits a marked anisotropy (oth/001 = 29 GPa, o'th/111 = 40 GPa). Calculated results compare favorably with experimental value of 24.7±3.6 GPa obtained for tungsten whiskers grown along the [110] direction. Similarly, in NiAl, the 'hard' orientation [001] differs very significantly from the [ill] orientation (oth/001 = 46 GPa, oth/111 = 25 GPa). This anisotropy is explained in terms of higher-symmetry structures present or absent on the calculated deformation paths. In disilicides, the theoretical strength is calculated for [001] loading (oth/001 = 37 GPa and 38 GPa for MoSi2 and WSi2 , respectively). The role of relaxation of internal structure parameter is discussed and changes in bonding conditions during the tensile test are analyzed.IntroductionIn most engineering applications, the strength of materials is limited by the presence of internal defects. If there were no defects, then, for example, the tensile strength could be several orders of magnitude higher and its value would be comparable with that of shear modulus. Therefore, the strength of ideal (defect-free) crystal represents an upper limit of attainable stresses, which is called the ideal strength. While it may not be possible to achieve the ideal strength in practice, it is not possible to exceed it. However, the ideal strength is already approached in situations which are technologically relevant. These include the low-temperature deformation of inherently strong materials, such as diamond, Si, Ge and some of the transition-metal carbonitrides, deformation of whiskers, nanoindentation of materials with low defect densities, hardened thin films and coatings etc. The ideal strength sets the limits of elastic stability of a solid. Its knowledge is useful for estimation of the ideal work of fracture stresses needed for homogeneous nucleation of dislocations and for modelling of crack propagation."

Jan 1, 2001

By Richard D. Hagni

Polished sections of pyrometallurgical intermediate products from a simulated commercial flash furnace were examined by reflected light microscopy, scanning electron microscopy-energy dispersive spectrometry and electron backscatter analysis, and microprobe analysis for phase and textural relationships. The smelter feed is a copper concentrate from a porphyry copper deposit. The concentrate consists primarily of chalcopyrite, bornite and pyrite with smaller amounts of covellite, chalcocite, molybdenite, magnetite, galena, and sphalerite. The flash furnace reactions for pyrite and chalcopyrite can be observed by reflected light microscopy. Reacted angular particles of pyrite exhibit successive rims of fibrous pyrrhotite and hematite or magnetite. Reacted angular chalcopyrite particles show successive rims of bornite, digenite, and chalcocite. Spherical particles, formed by the complete melting of former pyrite particles, consist of variable amounts of granular pyrrhotite with magnetite rims and minor hematite. Spherical particles, formed by the complete melting of former chalcopyrite particles, exhibit exsolution intergrowths with varying proportions of intermediate solid solution, bornite, digenite, and chalcocite and have rims of hematite, magnetite, and copper-iron spinel. Sphalerite and molybdenite do not show evident mineralogical reactions.

Jan 1, 1987

By Andreas Siegmund

Cast or rolled lead anodes employed in zinc electrowinning typically contain between 0.5?1.0% silver to decrease the overall corrosion rate. The production of cast lead-silver or lead-silver-calcium anodes often results in the formation of numerous holes, voids or laps in the anode surface that can initiate internal corrosion in localized areas. In rolled anodes the presence of internal porosity is significantly reduced, thus resulting in extended service life. The obtained grain structure of cast or rolled Pb-Ag anodes, however, requires a relatively long period of time to form a stable protective PbO2/MnO2 layer that can evolve oxygen without excessive lead contamination of the cathode. Therefore, these anodes are often mechanically, chemically or electrochemically conditioned prior to being placed in the electrowinning process. RSR Technologies has developed an improved anode for zinc electrowinning. The anode consists of a rolled Pb-Ag-Ca-alloy with controlled surface grain structure. The preferred calcium and silver content of the alloy is 0.05?0.08 % and 0.3?0.4%, respectively. Since May 2001, industrial-scale tests have been carried out at two zinc refineries in North America in industrial electrowinning cells. The controlled grain structure of these anodes allows forming an adherent protective oxide coating within a short period of several days when placed in an electrowinning cell without the necessity of being preconditioned. Anode sludge growth is evenly distributed. The anodes stay dimensionally stable and no short-circuits have been observed. Consequently, low corrosion rates and improved current efficiencies have been achieved.

Jan 1, 2003

By Sadi Medina

As it is characteristic from Custom Smelters, ENAMl Las Ventanas Smelter has to deal with different qualities and quantities of mining products from about 70 suppliers, that contain a variety of impurities that would be harmful for copper production. In order to increase the smelting capacity, an oxygen plant has been running since September of 1990. Moreover, to improve the environmental conditions, a new sulphuric acid plant started up to neutralize the metallurgycal off-gases from the Teniente Converter and partially from the Peirce-Smith converters. Based on the on-line operation among the reverberatory furnace and the Teniente Converter using oxygen enriched air to produce high grade matte, most of the volatilizing impurities, mainly arsenic, are collected as discarding compounds in the gas cleaning system of the acid plant. This paper describes the continuous performance of the Teniente Converter with acid plant, the results attained, the operation problems and how they were solved. The impurities distribution achieved in this process is also included.

Jan 1, 1993

By Cong Wang, Kexin Jiao, Yongan Zhao, Haibin Zuo, Jianliang Zhang

Traditional refractory materials for blast furnace hearth lining are mainly composed of carbon bricks and the ceramic cup. However, these materials can’t meet the demands for long service life design of blast furnaces. In this paper, a new refractory called carbon composite brick (CCB) was introduced, which combined the advantages of carbon bricks and the ceramic cup. In this case, the resistance of the CCB against corrosion was equal to the ceramic cup and the thermal conductivity of the CCB was equal to carbon bricks. From the results of more than 20 blast furnaces, the CCB could be well used in small blast furnaces and large blast furnaces. In the bad condition of low grade burden and high smelting intensity, the CCB gave full play to the role of cooling system, and effectively resisted the erosion of hot metal to improve the service life of blast furnaces.

Jan 1, 2015

By M. Girgis

The behavior of arsenic III during electrolytic refining of copper in acidic copper ?sulphate electrolytes was studied by different electrochemical methods such as, linear potential sweep, cyclic voltammetry, chronoamperometry and chronopotentiometry. The study showed that arsenic behaves as a depolarizing ion and has a deleterious effect on copper deposit. Three substrates; Pb, Cu and Ag were used during the refining process and the electrode kinetics were found similar for both Cu and Pb electrodes while a little difference was found for the Ag electrode. A microscopic study by scanning electron microscope was undertaken to show the influence of arsenic on deposit's morphology. Surface analyses of the deposit were carried out by some electronspectroscopic techniques such as Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The results showed that arsenic coexists with copper deposit at potential?~ -0.25 V.

Jan 1, 1987

By J. Wong

We report a successful use of x-ray absorption spectroscopy to probe the chemical and structural environment of trace elements in coal. When applied to vanadium in coal, it was found that vanadium exists in at least two environments: a trivalent site 6-fold coordinated by oxygens at ca. 2.0~ and a tetravalent site 5-or 6-fold coordinated also by oxygens, one of which forms a short V=O bond at ca. 1.6a. No evidence of nitrogen (porphyrin)1'or sulfide environment was found. It was also found that the vanadium environ-ments in the raw coal did not survive unchanged in a liquefaction process. These findings have implications for coal cleaning processes and for trace element release into liquefaction process streams.

Jan 1, 1982

By Luciano B. Oliveira, Luis G. C. Marques, Sergio N. Monteiro, Marcos V. M. Fagundes

"Biodiesel production is normally associated with large plantations of oily vegetables such as soybean and colza, in large rural areas. However, in the municipal limits of the city of Rio de Janeiro, southeast of Brazil, biodiesel is being produced from wastes commonly generated by typical urban activities such as sewage sludge, discarded fat from meat markets and post-used cooking oils. In the present work, the experience of producing biodiesel from urban wastes in Rio de Janeiro is assessed. The type of precursor materials, equipments and logistics are presented. The environmental and economical advantages as well as the drawbacks are discussed.IntroductionThe interest for a liquid fuel that could substitute those obtained from petroleum started more than one hundred years ago when Rudolph Diesel tested his no-spark internal combustion engine, impelled by compression, with peanut oil. By that time, petroleum was beginning to be extracted in large scale and no one was concerned with the future environmental problems and its eventual depletion. In the last century, the successful association of petroleum based fuels with the automotive industry was an almost insurmountable obstacle to any attempt to use nonmineral oils [1]. In addition to the greater efficiency and, by then, lower price of the diesel from petroleum, the use of plain vegetable oils introduced undesirable carbon deposits and reduced the engine lifetime. Today, the situation is reverse. The continuous increase in the price of petroleum and, above all, its contribution to climate changes are strongly motivating the use of biofuels to replace those obtained from fossil fuels such as petroleum, natural gas and coal [2].In the case of the common petroleum derived diesel, many countries are now engaged in large scale substitution programs. The USA should produce more than 700 million litters of biodiesel, while the European Community is expected too produce around 6.5 billion litters in 2008. In Brazil, the federal biodiesel program imposed a minimum of 2% addition to the common diesel. This would demand a production of 800 million litters in 2008 [3]. The Brazilian biodiesel is made from a diversified source of vegetables mainly castor bean, African palm and soybean. The main producers are agrobusiness firms located in large rural areas of the Brazilian hinterland [4]."

Jan 1, 2008

By M. Misra

The prediction and assessment of the reactivity of acid mine tailings has been a subject of numerous studies. The conventional approaches such as sulfur content, pH, net acid generating capacity and conductivity are used for assessing reactivity of the tailings. In this paper a new non-invasive Impedance Spectroscopy (IS) technique is used for the determination of reactivity and acid mine potential of tailings. This technique is also used to establish the long term stability and leaching propensity of the tailings agglomerated with alkaline binders.

Jan 1, 1994

By Donald R. Fosnacht

An investigation was initiated to obtain the scope of the problems associated with recycling various waste oxide materials generated at Inland Steel and to identify and? test techniques that could possibly aid in increasing the amount of waste oxide materials recycled to primary. operations. Based on the results of this work, several new techniques were developed ?and tested on ?a plant or laboratory scale. These include the use of cold-bond agglomeration methods for producing waste oxide agglomerates for use as a cooling agent or scrap substitute in steelmaking operations, and the use of various techniques for beneficiating blast furnace flue dust and soaking pit rubble so that the upgraded materials can be utilized in sinter plant or ironmaking operations. The physical and chemical characteristics of the waste oxide materials and the results of the laboratory and plant testing are discussed in this paper.

Jan 1, 1985

By N. M. Komkov

The main operation of obtaining zinc from sulfide raw materials by hydrometallurgical technologies is the oxidation roasting of zinc concentrates in fluidized bed furnaces. The technical-economic parameters are determined by the parameters of the roasting process, which depend on the composition of the initial raw materials, the temperature of the bed and on other factors. The predetermined roasting temperature is maintained due to the change of specific efficiency as well as to the quantity of the heat removed from the bed. The efficiency of caissons depends at a high degree on the composition and the thickness of the accretion formed on the surface of the caissons. Forecasting the roasting results is impossible unless we know the mechanism of the accretion formation. The aim of the present paper is the thermodynamic analyses of the behavior of the charge compositions under roasting and the determination of the potential mechanism of the accretion formation. The thermodynamic analyses show that under conditions of the oxidation roasting the thermodynamic probability of the formation of zinc sulfate is higher than the probability of the oxide formation until a temperature of873 OK is reached. The thermodynamic probability of the formation of the lead sulfate is higher than the probability of oxide formation in the entire temperature range of roasting. The probability of formation of ferrites and silicates of zinc decreases only insignificantly the sulfate stability. The results of the investigation of the accretions composItion formed under roasting of concentrates with particle sizes less than 0.02 J..lm (60%), containing 65% of sphalerite (ZnS), 12% of pyrite and chalcopyrite (FeS2 and CufeSz) each, 3% of galenite (PbS), 7% of silica and other non-ore minerals, have shown that the composition of accretion varies depending on the depth of the accretion layer. The accretions on the caissons and the thermo-siphons consist mostly of zinc sulfate (more than 50%). The accretions of forehamber consist mostly of zinc oxide. They also contain ferrites and silicates. The formation of the sulfate zinc accretion in the cold parts of the fluidized bed furnace (the caissons and thermo-siphons) may be explained by a lower temperature on the surface and probably by a catalytic influence of the present oxides in the formation of S02 and sulfates. The nature of the structure of the accretion in the hotter parts of the furnace may supposedly be explained by the formation of elemental vaporous zinc during roasting.

Jan 1, 2003

By J. W. Perez

A simple exponential model has been developed (Perez and Aplan. Process Mineralogy, VI, 1986) to describe the fractional yield of a given species out of a locked assemblage: Fractional Yield of Species A = a e X/U where 'X' is particle size and 'a' and 'U' are constants. In the present study, the general validity of this model has been further demonstrated. experimentally, for the liberation of coal and pyrite out of various raw coals and beneficiated fractions using a variety of crushing devices. Using data from the literature, the model is also shown to be applicable to the liberation of sulfide minerals out of ores.

Jan 1, 1987

By Petr Sulovsky, Jaroslava Ledererova, Miroslav Svoboda, Michaela Suchardova

"The thinning resources of natural raw materials necessitate an increased degree of waste material recycling. The building industry offers a range of technologies enabling incorporation of industrial wastes into building materials for construction purposes in an economically acceptable way. Our research is focused on finding the appropriate technologies for specific groups of industrial waste materials (IWM). The studied IWM involve coal combustion residues (CCR), desulphurization products, sludges, metallurgical slags, and various other wastes. Many of them contain increased amounts of toxic elements that can under certain conditions get released. In order to prevent this, each specific IWM requires finding the technology that best ensures the binding of toxic elements in the building matter are fixed for the long term.Introduction The sustainable development of mankind is more than ever viewed as a matter of resources. Many aspects of the switch from a throw-away to a recycling society concern one of the largest consumers of natural resources and producer of greenhouse gases, the building industry. One of the biggest tasks lying before the researchers in the field of building materials is to find substitute or alternative raw materials that would save the thinning reserves of natural resources. The most promising and natural way is to replace the traditional raw materials with rejected and unwanted products of industrial processes, classified as wastes. These of course are not produced with the primary intention of achieving some desired properties. The usage of industrial wastes therefore involves finding the optimal way of usage their existing positive (from the point of view of utilizations) properties and minimizing the impact of their undesired properties, i.e. from the perspective of the considered application."

Jan 1, 2008

By N. Krishna

The utilization of Electrochemical Impedance Spectroscopy (EIS) in conjunction with Atomic Force Microscopy (AFM) is a powerful surface characterization technique to study the role of sulfur formation during acidic oxidation of chalcopyrite. It has been established that the chalcopyrite dissolution kinetics is controlled by the formation of passive sulfur layer during leaching. The objective of the study was to characterize the intermediate sulfur layer formation at different oxidation conditions in acidic solution. The chalcopyrite samples were subjected to anodic oxidation and the oxidation process was analyzed using impedance spectroscopy. The sulfur growth on the chalcopyrite surface during oxidation was further analyzed using Atomic Force Microscope for sulfur roughness and grain size, peak height and sulfur growth.

Jan 1, 1999

By J. W. Ahlrichs

In gold exploration and metallurgical testing, the role of the mineralogist is to assist in solving problems with regard to (a) sampling, (b) gold occurrences, and (c) petrologic classifications of host rocks. The presence of "coarse" gold as a sampling problem can be overcome by various methods, including "screen fire assays," screened analyses and special gravity techniques which may be used to determine distributions of "coarse" versus fine gold. Determinations of mineralogic associations of gold usually require special separation techniques, accompanied by fire-AA-mineralogic assays of the products. After accurate mineralogic analyses are obtained for various products, quantitative distributions of refractory gold associations can be calculated by the use of simultaneous equations. Petrologic classifications are required by the geologist for mapping and interpretation of the various rocks. After the petrology and mineralogic differences of the rock units are determined, x-ray diffraction analyses of analytical pulps can be used for lithologic logging of drill cores. XRD logging is an efficient method for correlating lithologic units and alteration trends throughout a gold prospect.

Jan 1, 1981

By A. E. Isaacson

The U.S. Bureau of Mines is studying the effect of supercritical water, at 400' C and 3,500 psi, and subcritical water, at lower temperatures and pressures, on mixtures of minerals and metals to determine the possible applications of water at high temperature and pressure for processing these materials. This research was conducted using a flow-through bench-scale system. Copper-bearing minerals studied were chalcocite, chalcopyrite, covellite, and cuprite. In general, mixtures of copper minerals and pyrite reacted to form bornite. Intermediate phases formed were chalcopyrite and digenite. Similar reactions occurred between pyrite and metallic copper. A mixture of chalcopyrite and pyrite was inert in supercritical water'. The reaction between cuprite and metallic zinc yielded metallic copper. The cuprite was reduced by hydrogen generated by the reaction between metallic zinc and water. None of the reactions occurred exclusively in supercritical water, but also occurred in water at high temperature and pressure below the critical point. 'Experimental results did show that a dual-reaction process, consisting of solid-state diffusion and fluid transport, was occurring.

Jan 1, 1989

By Xiping Chen, Wangxing Li

"Spent potlining is unavoidable solid waste from aluminum smelters. About thirty kilograms spent potlining is discharged in China to produce per ton primary aluminum. Spent potlining has high level soluble fluorides and cyanides so that it brings heavy pollution to environment. It is prohibited to keep a large amount of spent potlining in open air because it will lead concentrated pollution to local soil and water source due to hydrated reactions between spent potlining and rain water/moisture in air. Landfill may solve pollution of spent potlining provisionally, but it is difficult to be accepted by aluminum smelters because of its high investment, troublesome monitoring and perennial maintenance. Detoxifying of spent potlining not only can remove deleterious fluorides and cyanides in SPL, but also can make fluorides in SPL recycle and return to aluminum electrolysis cells, at the same time benign SPL solid residue can be recycled and ready for cement production.IntroductionChina became the largest primary aluminum manufacturer in 2001. In the past few years, its aluminum output increased by twentyfive percent every year and reached 12.56 million metric tons in 2007. The whole world was very surprised and focused attention upon Chinese aluminum industry. It is more and more important to keep sustainable and steady development with the rapid development of Chinese economy. Aluminum industry is an important base industry and does a great contribution to Chinese economy. But aluminum industry is high energy-consumption and heavy-pollution industry. The government has paid more attention to aluminum industry in recent years. Nowadays the bothersome problem which counterworks Chinese aluminum industry is pollution from solid wastes. Main Solid wastes from aluminum industry are red mud from alumina refineries and spent potlining (short as SPL) from aluminum smelters. Spent potlining are waste lining materials from aluminum electrolysis cells. During production of aluminum, due to reactions between melted electrolyzer and pot lining as well as penetrating of fluorides into pot lining, newly-formed compounds inlayed in pot lining, destroyed the lining structure and brought pot lining cracking. Melt rushed out of lining cracks, cells have to be stopped running and ready for heavy repair. Cell life generally varies from 1500 to 2000 days. Spent potling is an unavoidable solid waste from aluminum industry."

Jan 1, 2008