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By Tiejun Chun, Jian Pan, Deqing Zhu, Zhiyong Ruan

"In this paper, the desulfuration of pyrite cinder pellets was carried out. Phase analysis shows that most sulfur of pyrite cinder exists in the form of elementary sulfur. Most sulfur was removed in preheating stage. 81.25% sulfur was removed and the average SO2 concentration of exhaust gas was 1365ppm when the pellets were preheated at 950oC for 9 min. The final product, assaying 62.42wt%Fe and 0.02wt%S content at 96.88% desulfuration was achieved under the conditions of preheating at 950? for 9 min and roasting at 1200? for 15 min, which can be used as the burden for blast furnace.IntroductionPyrite cinder, as a subsidiary product of sulfuric acid production by roasting of pyrite ores, was solid waste in sulfuric acid enterprises. According to the statistics, the annual production of pyrite cinder is about 15 million tons in China. Besides, there is lots of pyrite cinder deposited for many years [1-3]. The pyrite cinder consumed in the cement and other industries as auxiliary additives only accounts for less 30% of its total discharge and the left is stored in waste pond, occupying much land and polluting environment in China [4-5]. Moreover, pyrite cinder contains iron between 30-63% which can be utilized as a cheap raw material for ironmaking by sintering or pelletizing processes, which can not only prevent pollution but also provide cheap raw materials for ironmaking [6-7]. However, compared to traditional iron ore concentrate, pyrite cinder possesses higher sulfur content."

Jan 1, 2012

By P. Chris Pistorius

An example is presented to illustrate the joint effect of local reaction equilibria and mass transfer limitations, for reactions during ladle refining of steel. The example relies on some of the kinetic principles that David Robertson has employed to quantify many metallurgical processes. In calcium treatment of alumina inclusions in aluminum-killed steels, solid CaS forms as an intermediate reaction product. During subsequent reaction, CaS disappears and calcium aluminate forms; at the same time, aluminum and sulfur dissolve in the steel. Kinetic analysis shows that the rate of this reaction is not limited by mass transfer of dissolved aluminum and sulfur away from the reacting inclusions. The reaction rate is likely limited by transport of dissolved calcium. This example also illustrates the use of FactSage macros for kinetic modeling.

Jan 1, 2014

By Georgeta Rata, Cornelia Petroman, Ioan Petroman

"Proper training and education in the field of recycling and waste treatment are inconceivable without the proper teaching of the terminology specific to both recycling (aerospace products recycling, automotive recycling, general recycling, recycling behaviour, recycling schemes, recycling systems, and waste recycling) and waste (characterization of waste, electronic waste, heavy-metal containing waste, monitoring of waste, radioactive waste, solid waste, waste collection, waste conversion, waste recycling, waste reutilization, waste stabilization, waste storage, and waste treatment) in both the students’ mother tongue and in English for Special Purposes (ESP) as a second language (with focus on the structuring of the specific terminology). Including linguistic approaches among the possible approaches of environmental protection and material sustainability means including linguistics among the various disciplines addressing energy supply, cement and building materials, metallurgy, chemistry, glassware, pulp and paper industry, machinery, automobile and electronic industries, collection, and sorting, further treatment and final disposal of post-consumer material.IntroductionCultural and technical changes have produced more novel artefacts than novel activities or novel properties, generating new vocabulary needs that are readily answered by new words (nouns).The purpose of this research is to show that ‘waste words’ – phrasal words (items that have the internal structure of phrases but function syntactically as words, e.g., cattle waste) and particularly compound nouns (words formed by combining roots, that tend to have a meaning that is more or less idiosyncratic or unpredictable, e.g., wastepaper ‘discarded paper’) – used in the study of the English of recycling, waste treatment, and clean technologies can be misleading for both native and non-native students and/or users of English because their structure alone does not allow instant, proper understanding of their meaning.Our hypothesis is that this inconvenient can be overcome by getting to reach the proper meaning of these new words. Or, arriving at the precise meanings of the ‘waste words’ depends on our knowledge of the world (for example, wastepaper indicates that some used paper is discarded and not wasted) rather than on purely linguistic knowledge."

Jan 1, 2008

By Yong Hack Lee

Nonferrous smelting processes have been through a rapid transformation since the beginning of 1980. The copper smelting technology has changed from the conventional Blast Furnace process to the Flash Smelting and MIB process. In the field of lead smelting, the technology has changed from the Blast Furnace Smelting to the Direct Smelting such as QSL and KIVCET. In 1992, Onsan Refinery successfully commissioned Direct Smelting QSL technology for lead. The QSL could produce more than 160,000 ton per year of lead bullion from lead concentrate and various residues. Moreover, since the year 2000, the TSL (Top Submerged Lance) Technology utilizing the same Direct Smelting process has been successfully commissioned to treat lead concentrate as well as lead sulfate residue produced from a hydrometallurgical zinc plant. This paper presents and compares the energy flows of lead smelting processes such as a conventional process and the Direct Smelting Processes plotted on the Pb-O-S phase diagram. The oxygen potential diagram suggests how to control the oxygen potential in the fum ace. Also, it describes the recent operational experience in the TSL plant of Onsan Refinery with necessary mass balance of key elements.

Jan 1, 2003

Physical and chemical properties of the salt flux phase play a significant role in the recycling of UBC in Aluminum melting processes. Particularly knowledge of several properties such as salt vapor pressure, melting temperature, loss of aluminum, corrosion of refractories are useful for the process control decisions in order to attain a good quality of aluminum produced. A literature review and analysis of several salt flux systems for the selection of a flux for the Aluminum melter (low temperature natural gas bath melting) process were made. Based on these analysis two salt flux systems are recommended for further studies. These are NaCl?KCl?LiF system and NaF?LiF?KCl system with small amounts of other salt additives. Application of these fluxes to Al industrial processes are discussed.

Jan 1, 1996

By T. Wang, R. G. Reddy

"The corrosion of stainless steel SS316L in a low melting point novel LiNO3-NaNO3-KNO3- NaNO2 eutectic molten salt mixture was investigated at 695K. After long-term isothermal dipping corrosion experiments, the SS316L samples were analyzed using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) to determine the topography and corrosion products. Dense and protective lithium iron oxide scale formed on the surface and prevented the SS316L sample from further severe corrosion. Therefore, SS316L is considered to be suitable construction material for solar thermal energy storage materials containers.IntroductionMolten salt mixtures have been considered as potential candidates for thermal energy storage and heat transfer media in solar energy applications. To apply the molten salt in the energy transfer process, the standard pipes made of stainless steel must be utilized to carry the molten salt mixtures in parabolic trough system of solar power production. The pipes encounter continuous flow of hot and cold molten salt every day. Thus corrosion of stainless steel in molten salt mixtures becomes extremely essential for the long-term utilization of the thermal energy storage media. The corrosion of passivity materials inside high temperature molten salt systems have been studied which gives fundamental understanding of basic mechanism about the corrosion process [1-8].The corrosion behavior of Fe-Ni-Cr alloys in an equi-molar LiNO3–NaNO3–KNO3 mixture was studied [9]. According to the XRD analyses, the major phases in the oxide scales were identified as LiFeO2, Fe3O4 and Cr2O3. A HITEC® salt mixture (NaNO3–NaNO2–KNO3) was also tested as a corrosion medium for stainless steel [10] and the corrosion rate was found to be affected by the protective oxide layer. In most cases, the alloys having more than 10wt% chromium show high resistance to corrosion in molten salts."

Jan 1, 2014

By Animesh Jha

"Fine ceramic powders (<500 nm) exhibit exceptional physical and mechanical properties in engineered structural ceramics. The production of fine powders, in particular the non-oxide ceramics, via a cheaper route than the organic solvent route has been rather elusive. This paper examines the physical chemistry of sub-oxide vapour-phase reduction reaction for the nucleation of non-oxide ceramic phase. Well known vapour species eg SiO and BO in the production of technical ceramic powders (SiC, BN) are particularly discussed for understanding the nucleation process of SiC and BN ceramic phases respectively. The regimes of partial pressures and temperatures are particularly 'identified. The calculated nucleation rate as a function of the temperature is compared with the experimental results on powder morphology. The production of amorphous and nanocrystalline h-BN powders is discussed in the context of substrate structure and thermodynamic parameters.IntroductionThe physical and mechanical properties of ceramic components are strongly dependent on the powder particle size and morphology used for their fabrication. For example the strength (Os) of the structural ceramic components increases with decreasing average grain-size (d) in accordance with the Hall-Petch relationship: Os = 0""0 + k/(d)1/2. Here k is an empirical constant which can be established from the graphical relationship. However as the particle size approaches submicrometer-size range, the dependence of strength on the particle size becomes more complex [1]. The design of ceramic components based on nanometer-size particles have recently become an important field which can offer ceramic materials with properties comparable to their metal counterparts. Several materials based on these concepts have been developed and reported by Niihara [2]. For example, the Al2O 3-SiC nanocomposite, having average B-SiC grain size 0.3-2um with intragranular SiC particulates of 5-10 nm has unusually high strengths (1100 MN/m2) at low and elevated temperatures combined with enhanced fracture toughness (> 4 MN-ml.5) which is an unusual combination in structural ceramics. Besides mechanical properties, as the particle size of ceramic powders approaches the nanometer-size range, the charge transport properties also improve by many times. The effect of particle size on the electrical conductivity of Si3N4-TiN composites has been well documented [3.4]. The size of ceramic particulates without doubt plays a pivotal role in determining the properties of ceramic components."

Jan 1, 1996

By Tobias Dubberstein, Hans-Peter Heller

The viscosity of Fe-Cr-Mn-Ni TRIP/TWIP (Transformation Induced Plasticity, Twinning Induced Plasticity) steel with varied nickel content is investigated using a vibrating finger viscometer. The viscosity of the melt is calculated from the change in power input in the field coil by an immersed finger into the liquid steel to maintain a constant peak-to-peak amplitude of the sine wave of oscillator compared to the idle state. Nickel content in steel is varied from 3 wt% to 9 wt%. The dynamic viscosity (η) at 1600 °C for 3 wt% Ni is 3.73±0.14 mPas, for 6 wt% Ni 3.50±0.03 mPas, and for 9 wt% Ni 3.93±0.09 mPas. There is a kink from low to high nickel content in viscosity values of Fe-Cr-Mn-Ni alloys. This phenomenon can be explained by a change in coordination number in the melt, as reported for Fe-Ni binary system in literature. The availability of viscosity data delivers relevant input to model free fall atomization processes of FeCrMnNi alloys.

Jan 1, 2015

By L. A. Barta

A new process for the leaching of chalcopyrite concentrates has been developed and tested in miniplant campaigns and locked cycle testwork carried out between 1996 and 1999. The process involves pressure leaching in a sulphuric acid solution, e.g. raffinate from copper solvent extraction. Iron in the feeds is precipitated predominantly as hematite in the autoclave, simultaneously with copper extraction. Gold and silver in the pressure leach residue are recoverable by conventional cyanidation, following flotation to remove elemental sulphur by-product. The results of recent miniplant tests and batch locked cycle tests are provided.

Jan 1, 1999

By Eiji Iwamura

"Two types of diamond-like carbon (DLC) films with different microstructures were prepared by unbalanced magnetron sputtering, and the tribological properties of the nanoscaled DLC multilayer coatings consisting of alternating layers of graphitelike and amorphous-like microstructures were examined. The DLC microstructure was characterized by certain features of graphite-like clusters, in that some of them had onion-like structures. The films filled with the clusters were obtained in a condition with an incidence of high influx of energetic electrons, and the other films without apparent cluster structures were formed in a condition with ion bombardment controlled by negative bias voltage applied to substrates. Stacking each film layer-by-layer, the nanoscaled multilayered coatings showed superior tribological properties to individual single-layered films due to the combination of properties induced by the difference of microstructures.IntroductionIn various tribologiql applications, it is necessary for diamond like carbon (DLC) coatings to have adequate adhesion, significant hardness and a concomitant low friction coefficient. A number of deposition techniques and coating structures have been proposed to achieve suitable DLC properties [1-3]. However it is still difficult to obtain a satisfactory level of combination of the properties particularly desirable for engineering applications.In this study, the features of unbalanced magnetron sputtering were demonstrated with the effect of ion and electron bombardment. Two types of microstructures , namely amorphous-like and graphite-like, were prepared by changing the condition of the charged particles bombardment during deposition. Using the difference of properties induced by the microstructures, nanoscaled DLC multilayered structures were examined in an attempt to improve tribological properties."

Jan 1, 2000

By Kathryn C. Sole

A novel solvent-extraction process for the refining of gold was recently commercialised, with the commissioning in May 1997 of a 24 t a-&apos; refinery at Harmony Gold Mine in Virginia, South Africa. The MinataurTM Process (Mintek Alternative Technology for Au Refining) uses solvent-extraction technology to produce gold of 99.99% purity from the cathode sludge arising from a conventional carbon-in-pulp / electrowinning circuit. Implementation of this process introduces significant cost benefits compared with the conventional dore smelting / toll-refining route previously followed. This paper outlines the process, presents selected operating results obtained during the first few months of operation, and provides some details of the associated techno-economic advantages.

Jan 1, 1998

By Lu-ming Zhao, Li Zhao, Yu Wang

Mould flux is a vital functional material which is based on silicate including flux and framework material. The effects of magnetic field intensity and frequency on viscosity of mould flux were tested by rotational viscosity tester and a measurement device for electromagnetic characteristics of mould flux viscosity under high temperature conditions. The results show that: with the magnetic field intensity rising (0 –30 mT), the viscosity of mould flux increases by 1.3–1.8 P. With the frequency rising (6–12 Hz), the viscosity of mould flux is increased by 1.2–1.4 P. When the binary basicity is 1.08, the viscous flow activation energy increases with the increase of the magnetic field intensity and frequency. It can be the main reason for the increase of mould flux viscosity that the electromagnetic forces disrupt the ordered structure of mould flux and make the ion migration rate increase.

Mar 1, 2018

By Cong Wang, Siyang Long, Pengcheng Zhang, Haibin Zuo

The present study describes central segregation of the High-carbon steel billets of 150mm square and its heredity to the following hot-rolled wire rods, whose sizes are 10mm and 6.5mm in diameter separately. The relationship between center segregation of the billets and solute element distribution of rods, the mechanical properties and microstructure of rods were studied experimentally. The results show that segregation index of C is higher than that of Mn. With the increase of central segregation, the stability of the mechanical property of the rods becomes worse. The formation of carbide network and central martensite in the rolled products can be attributed to the heredity of the as-cast central segregation. The 6.5mm-diameter-rod has higher tensile strength than that of 10mm diameter which might be due to bigger reduction ratio. Thermo Mechanical Control Process (TMCP) should be used together with Billet Centersegregation- controlling (BCSC) to improve the overall properties of rolled products effectively.

Jan 1, 2016

By H. Fukuyama

The wetting behavior of single crystalline MgO by fayalite-type slag melts has been studied by the sessile drop technique incorporated with high temperature X-ray radiography. The experiments were performed under oxygen partial pressures of 10-6 and 10-4 Pa at 1473 K. Mass ratios of iron to silica, Fe/Si~, in the slag employed were 1.4 and 2.0. To investigate the interfacial reaction, experiments using high density MgO crucibles were also conducted. The reactions at the interfaces were examined by Electron Probe Microanalysis. The contact angles between the slag melts and the MgO substrates were found to be relatively low, ranging from 30 to 10 degrees. The surface tension of the slag was 0.4 N/m for a slag of Fe/Si02 = 2.0. Two phases, magnesiowiistite and olivine, were observed at the interface. Interdiffusivity in magnesiowiistite solid solution was determined as a function of iron oxide content. Phase relations between magnesiowilstite and olivine, and the growth rates of both phases, are also discussed

Jan 1, 1996

By Henrique Kahn

The Anitapolis alkaline massif in southern Brazil underlies a sub circular area of 6 km2. Bore-hole data show a concentric rock distribution, with mafic rocks in the central part and felsic rocks in the border zone. The rocks are covered by talus and weathered material, 30 m thick on average, and very inhomogeneous in composition. Phosphate mineralization associated mainly with two levels of the weathering mantle and with fresh rocks. A preliminary ore-type classification was based on distribution of apatite, feldspar, vermiculite, biotite-phiogopite, calcite, pyroxene, amphibole and analcime, determined by semiquantitative diffraction method. Technological tests performed on eluvial ore samples from three adits resulted in a subdivision of ore-types based on the difference in behavior due to mineral characteristics during mineral pr

Jan 1, 1991

By Xin Zhang, Xu Zhang, Hao Bai, Ning Li

Organic Rankine Cycle (ORC) is an effective technology for low-grade waste heat power generation. In this paper, the thermal-dynamic performance of ORC system, in which low-temperature waste heat (from 40-140oC) is used as heat source, was evaluated with software RefProp8.0. The result indicates that in the range of low temperature, the working fluids like R601, R601a, R600a, R141b, R245fa and R245ca have better thermal performance. Furthermore, pilot-scale experiment using R245fa as working fluid was conducted, which validated the operation of the system for low-grade waste heat recovery. Finally, the economic feasibility of ORC has been analyzed for an ORC system using the waste heat from quenching water of blast furnace slag (80oC). According to the analysis, the project is reasonable in economy because the recovery period of investment is less than 4.2 years and environment-friendly since the CO2 emissions can be reduced by almost 43650.68t annually.

Jan 1, 2016

By Gennady I. Gulyayev

A mathematical model of plastic deformation occurring in cold plug drawing of mother tubes with initial cross-sectional wall thickness variations (CSWTV) has been developed. The main provision of the model is that eccentricity em is of such value that projection of all forces acting upon the plug in the deformation zone along the axis perpendicular to the drawing axis equals to zero. Calculations have proven that with other conditions being equal increase in the die cone angle and the deformation cycle number reduces CSWTV. Theoretical findings were confirmed by practical results. Keywords: cold, drawing, plug, die cone, plastic deformation.

Jan 1, 2003

By R. Y. Wan

Low grade sulfidic-carbonaceous refractory ore from Newmont Gold Company&apos;s Carlin deposit was microbially pretreated. The biological pretreatment process gave partial oxidation of the sulfidic components of the refractory ore but the preg-robbing carbon continued to be active resulting in approximately zero cyanide gold extraction. A 495 ton pilot plant test heap was conducted using acidic thiourea leach following biooxidation. Activated carbon and cation exchange resin adsorption were tested for gold recovery from the thiourea pregnant solution. The results obtained from the test heap were not satisfactory. Gold extraction was low due to slow reaction kinetics which was caused by relatively large particles and very low winter temperatures. Problems existed in the thiourea-test heap and are discussed in this paper. An alternative heap leach process using thiosulfate has been successfUl at the pilot scale for gold extraction following biooxidation pretreatment of refractory sulfidic-carbonaceous ores.

Jan 1, 1995

By Mark Kruzynski, Srinivas Garimella, James T. Wiswall

"A flue gas recirculation (FGR) system for a combustion fired aluminum melting furnace is experimentally investigated. The FGR system flows combustion air in a turbulent jet within the flue gas stream, and the turbulent jet flow is collected in a tube at a distance from the jet exit. Entrainment of the flue gases as well as heat transfer between the flue gases and the jet occurs over the length of the exposed jet. Heat transfer between the flue gases and the jet, and the amount of flue gas entrained into the jet (derived from temperature, flow rate and oxygen fraction measurements) were measured as a function of nozzle exit velocity and the distance between the nozzle exit and collection tube. In addition to flue gas entrainment, a fuel savings of up to 7%, due to heat transfer over the length of the jet, was projected from the measurements obtained.IntroductionFlue gas recirculation can be applied to aluminum melting furnaces to control combustion temperature. When coupled with a device to improve furnace efficiency by recovering heat from the furnace exhaust, flue gas recirculation provides a control technique that is integral to achieving the goals of reducing fuel consumption, increasing product yield, increasing the longevity of infrastructure, and reducing pollutant emissions. In particular, combustion temperature control can help reduce reactivity of the products of combustion with the molten metal surface and furnace refractory materials. Combustion temperature control can also help improve the life of heat exchangers used to recover energy lost to the environment in the flue gases, and reduce NOx formation in the combustion process. Flue gas recirculation can also dilute oxygen used in oxy-fuel combustion to reduce reactivity.Flue gas recirculation has been used since the 1970s to control flame temperatures in the automotive industry [1-3] and has successfully reduced NOx emissions. Many different flue gas recirculation approaches for high temperature melting such as melting aluminum and glass have been patented since the 1980s [4-12]. There has also been academic interest to determine the fundamental performance characteristics of flue gas recirculation in high temperature furnaces and in combustion [13-15]."

Jan 1, 2014

By Shengli Wu, Juan Zhu, Wei Huang, Xinliang Liu, Kaiping Du, Kaifa Zhang

Based on the furnace burden of high content of Al2O3, the process of softening and melting and the characteristic of primary slag were studied with the increase of MgO content in the sinter and adding some MgO into the pellet. The results showed that the content of MgO in the primary slag increased with the increase of MgO in the sinter and pellet. Meanwhile, the permeability of the furnace burden was improved because of low viscosity of high MgO primary slag. Compared with the increase of MgO content in the sinter, the increase of MgO content in the pellet can improved the softening and melting characteristic of the comprehensive furnace burden more effectively. More Mg-bearing pellet should be chosen in the comprehensive furnace burden for the purpose of improvement the fluidity of primary slag and the permeability of the furnace burden in the burden of high Al2O3 content.

Jan 1, 2015