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By Jiang Fan, Wang Haigang

"The three-dimensional complex multiphase turbulent flow in U-beam separators was simulated using the Reynolds stress equation models (RSM). To account for the effect of the stochastic characteristic of the instantaneous gas velocity on the particles, the improved Lagrangian stochastic model based on the Reynolds stress model for gas phase was adopted, which attributed to the successful prediction of the turbulence anisotropy and particle crossing trajectories effects. The interaction between the particles was also considered using the HardSphere model. To treat the particle-wall collision, the influence of the roughness of the wall on the motion of the solid particles was taken into consideration by imposing random collision angles. The result from this study not only shows the dynamic characteristics of the multiphase flow- in the separators, but also gives the relationship among the efficiency, structure and pressure losses of the separator.IntroductionCirculating fluidized bed (CFB) combustion is one of the most promising clean coal techniques. A main feature of CFB boilers is the un-delayed recycle of solid, coal and sorbant particulate, in an external loop. Separator, which is required to separate the solid particle from the flue-gas leaving the reactor of CFB, plays an importance role in the external solids recycle loop. It affects the combustion of CFB system greatly. Presently cyclone is the most commonly used as separators for CFB system and other chemical industrial processes. It provides high level of separation for CFB system for fine particles. However it suffers from some inherent disadvantages. It's volume and size is huge. Moreover, it is difficult to design and install when the CFB workload rises. The application of U-beam separators instead of hot cyclone separators in CFB boilers has many advantages. Publications indicate proposals or successful use of Ubeam separators in Swedenr11, USA 21, Russia r3land China [4]• But it is not possible to find results in the literature of detailed investigations of this new. type of separators or recommendations on the choice and calculation of an optimal design. For this reason, numerical simulation for the three-dimensional gas-particle two-phase flows with several rows of vertical U-beam elements, local in the chess order and blocking a way of outgoing from a CFB boilers dusted gases was carried out in this study."

Jan 1, 2004

By F. Qian

Direct impingement of molten metal baths by a gas jet is commonly encountered in such processes as BOF and electric arc furnace steelmaking. Shape and local fluid mechanics in the impinging region is important because it determines the interaction of the metal pool with the surroundings. Goal of the present work is to characterize and understand the interfaces at the impinging region. Using a physical model consisting of water/corn oil and water/kerosene as surrogates for metal/slag, interface shapes for slag-gas, slag-metal and metal-gas are investigated. Influence of transport properties of the two liquids on the shape and flow fields are also experimentally determined under various impinging jet conditions, namely jet momentum and jet height. The viscosity of the slag layer (corn oil or kerosene) has the most significant effect on the interface shape and the induced flow fields. The interface shapes were measured both photographically and by using a surface- tracking resistance probe. The limiting condition at which the jet breaks through the corn oil or kerosene layer and reaches the water layer was determined experimentally

Jan 1, 1994

By J. C. Agarwal

Most metals are produced from minerals containing one or more of the desired metals, some contaminating metals, silicate, oxides, carbonates, and sulfides. Therefore, in the production of metals, there is generally a gaseous effluent in pyrometallurgical processes and a liquid effluent in hydrometallurgical processes. There are also solid residues such as waste ore, tailings, dust, and slag, created by the metal recovery processes. There are two important distinctions between the effluents and the residues: I. Effluents ? gases and liquids ? affect the neighboring environment for miles from the point of emission, while residues affect only the soil on which they are stored or dumped. 2. The environmental and economic effects of effluents are known and felt essentially immediately. By contrast, the environmental effects of the residues may not be known for a long time. For these reasons, the economic impact and the potential corrective actions required are very different for effluents and residues.

Jan 1, 1992

By Linfeng Zhou, Rong Sun, Guanghui Li, Zhiwei Peng, Tao Jiang

Dust, or airborne particulate matter, from metal smelting can be either mechanically or thermally generated and it negatively affects the indoor air quality as well as the fugitive emissions from the plant. The thermally generated dust is often referred to as fume and it is typically generated whenever liquid metal comes into contact with air. For practical reasons, such as vehicle access, etc. it is often difficult to collect 100% of the fume. It is therefore highly desirable to develop processes and optimize operational procedures so that fuming can be kept to a minimum. In this series of experiments, the mechanism of active oxidation and fume formation from liquid silicomanganese under an impinging air jet in the temperature range 1400-1600°C has been explored. Characteristic properties of the fume have been established; particle diameter, shape, size distribution, and elemental composition are reported. The oxidation process is described in terms of vaporization, oxidation and agglomeration. In the boundary layer, two competing mechanisms seem to be operative in parallel: a direct oxidation of Mn vapor, and a two-step oxidation of silicon. The thermodynamic and kinetic conditions governing the two mechanisms are discussed.

Jan 1, 2016

By Fuming Wang, Lifu Hu, Changrong Li, Ruipeng Pang

The solidification structure of 430 ferritic stainless steel has been calculated in the solidification process by using 3D-CAFE model under the condition of water cooling. The calculated results consistent with those obtained from experiment. Under watercooling condition, the solidification structure consists of chilled layer, columnar grain zone, transition zone and equiaxed grain zone

Jan 1, 2015

By Sudha Goel, Manis Kumar Jha, Deblina Dutta, Rekha Panda

Based on the placement of lead and its consumption in industry bran- ches, the paper deals with the composition of lead in the massive of Kopaonik. Removal, tenuity and grinding of galenit. The paper in particular treats the flotation process, and also treats physico-chemical bases of reagents in the process, as well as decanting, drying, filtering and storage of concentrates. Veri fication of the chemical composition of Pb concentrates with Pb, Zn, Bi, As, Sb, In, Au, Ag, etc. It is special that in Kopaonik massive the ratio of Pb: Zn composition is 1.4:1.0 and during the flotation lead is inclined to go with pirotines concentrate more than is allowed. We are strongly focused to maximally decrease the Pb amount that goes with pirotine concentrates and wastes. The paper as such gave the first effects in optimizing of these parameters with positive effects in flotation process in Trepca.

Mar 1, 2018

By C. H. Tsau

The intermetallic compounds of Ni-25Al-xFe, x is 20-40 at.%, were prepared by arc melting and drop casting into ingots, and were rapidly solidified into ribbons by melt spinning. The microstructure evolution of these alloys with varied Fe content were examined by the x-ray diffraction, optical microscope, scanning electron microscopy and transmission electron microscopy. The results reveal that two phases, {y'} and {B} phases, are existing in the alloys with low Fe content, and the microstructure changes from the mixture of y' and {B} phases to a single 0' phase when the Fe-content reaches to 40 at.%. Also, the formation of y' phase will be suppressed by rapidly solidified process. For annealing both of the melt-spun and the cast specimens, a disorder 0 phase was revealed in both of the ribbon and the cast ingot of Ni-Al-Fe alloys with higher Fe content. In addition, increasing the increment of iron which substituting nickel in this alloys results in increasing the lattice parameter of both {y'} and{B} phases.

Jan 1, 1992

By Sergio N. Monteiro

Jute fabric obtained from discarded sackcloth is a promising low cost and post-used material being considered as reinforcement of polymeric matrix composites. In particular, the combination of this fabric with a recycled plastic constitutes an environmentally correct composite with both economical and environmental advantages. The present work investigates the toughness of recycled polyethylene composites reinforced with up to 40 wt% of post-used jute fabric extracted from discarded sackcloth. Standard Izod notched specimens were impact tested and the results showed an increase in toughness with the amount of jute fabric. Observation of the composite fracture by SEM revealed that the fabric weave, in spite of damages caused by the previous use of the sackcloth, act as an effective obstacle to crack propagation.

Jan 1, 2009

By Lijuan Li, Zheng Lu, Xin Xia, Qijie Zhai, Qingchun Li

"Pulsed current and pulsed magnetic field have been applied to the bainite transformation of Cr5 steel. Three groups of experiments were conducted. In the first group, ordinary resistance furnace was used for heat treatment. The Cr5 specimens were rapidly heated up to austenitization temperature 940 °C, held for 20 min, air cooled to bainite transformation temperature 350 °C, held for 10, 20, or 40 min and then air cooled to room temperature. The second and the third group shared the same temperature-time curve with that of the first group, but their heat resources came from the Joule heat produced by pulsed current. 1.5 T pulsed magnetic field was exerted on the third group specimens when they were held at 350 °C, but the second group specimens did not undergo the treatment of magnetic field. It was found that both pulsed current and pulsed magnetic field obviously retarded the bainite transformation. The phenomena were discussed in terms ofliterature results.IntroductionApplying pulsed current and pulsed magnetic field technology are very pronnsmg ways to change the microstructure of materials by affecting the phase transformation process. People had found that pulsed current dramatically influences the behaviors of materials, for example, electromigration effect [l], the solidification of metals and alloys [2, 3], electroplasticity [4, 5], crystallization of amorphous alloys [6], healing of metal materials [7] and so on. As to pulsed magnetic field technology, a lot of effort had been spent on grain refinement in solidification of metals [8, 9], recrystallization of cold-worked metals and alloys [10] and Fe-based alloys solid-state phase transformation [11, 12]. Though application of pulsed current and pulsed magnetic field technology have proliferated in recent years, investigation on their effects on solid/solid phase transformation, especially bainite transformation, is lacking. The aim of this paper is to show the effects of pulsed current treatment (C-T) and the combined treatment of pulsed current and pulsed magnetic field (CM-T) on bainite transformation of commercial Cr5 steel"

Jan 1, 2014

By Naixiang Feng, Kun Zhao

This work presents a two-stage aluminothermic reduction process for preparing Ti and Ti-Al alloys using Na2TiF6. Al-Ti master alloy and pure cryolite as co-products could be obtained. After the first stage reduction, the oxygen content of the metal product is reduced, and the second stage produces high-purity titanium or Ti-Al alloys with cryolite and Al-Ti master alloy as recyclable co-products.

Mar 1, 2017

By H. Sieber

Multilayer samples of tantalum and aluminum with the composition of Al-25Ta were prepared by cold rolling of elemental foils. The microstructure and phases were characterized by XRD, SEM and TEMISAED and the reactive phase formation was examined by DSC and DTA measurements in multilayer foils rolled for different deformation levels. The rolling procedure yields a decrease of the Ta particle size in the Al matrix and also results in the formation of a multilayer structure with a thickness of the elemental foils down to 200 nm in average. No phase formation is observed during the cold rolling procedure. While XRD and DSC measurements show no phase formation up to the melting of aluminum for samples rolled up to 40 F&R (fold and rolling) passes, in samples rolled for 50 or more F&R passes a first phase formation reaction yield an interfacial layer of TaAl3. Contrary to former studies in the investigated cold rolled Al- 25Ta multilayers the reaction starts at temperatures as low as about 340°C. The first stages of the reaction are associated with two exothermic maxima, that increase in amplitude and shift to lower temperatures with increasing number of F&R passes. At higher temperature the TaA13 reaction layer thickens very sluggishly and yields a third exothermic maxima at about 600°C. Isothermal DSC scans show the reaction is not finished for samples containing elemental particles larger than 1 pm after annealing at 550°C for 5h. In all the investigated samples no Al- Ta phase other than Tad3 was observed to grow for heat treatments up to 800°C. Multilayer samples heated up to 1400°C show a morphology consisting of small AITa2 particles embedded in a single phase TaA13 matrix. The multilayer microstructure and reaction product morphology are characterized by SEM and TEM investigations in cross-section and plan view geometry.

Jan 1, 1998

By Yanhui Sun, Yanan Zeng, Kaike Cai

"Hot ductility of Nb-V-containing steel has been studied by theoretical calculation and thermal simulation experiment. Meanwhile, microsegregation and precipitates were analyzed. The results showed that segregation degree of elements S, P, 0 is greater in mushy zone, while, the hot ductility was deteriorated by inclusions of Fe(S,O), (Fe,Mn,Si,Al)(S,O) in the interdendritic region. At the temperature 1100°C, a few NbN particles, 60-70nm, have little effect on mechanical property. In the temperature range 1000°C to 975°C, R.A declined rapidly from 82.36% to 69.61% with the diameters decreasing from 20 to 10nm and quantity of particles increased 23 to 45inds/µm2, respectively. In the temperature range from 900°C to 850°C, R.A reduced unobviously from 34.27 % to 30.01 % with ferric films thickening gradually. The critical stress, 52.38MPa, was equal to tensile strength at 975°C. Intergranular fracture was easy to occur with higher critical stress below 975° C.IntroductionProductivity and product quality of slab are seriously affected by cracks during continuous casting and the influencing factors of cracks are various[l]. From microcosmic angle, resisting deformation ability of initial solidification shell decreases obviously with solute elements segregation which can urge the low melting point ofliquid film to form at grain boundaries[2, 3]. Meanwhile, with temperature decreasing, particles would precipitate as the practical solubility product is greater than equilibrium solubility product. The carbonitrides would lead to stress concentration at austenite grain boundaries. Therefore, the transverse cracks of microalloyed steel would form during the straightening operation in the continuous casting process. The hot ductility of steels in the temperature of mushy zone was characterized by microalloy elements segregation, zero strength temperature (ZST) and zero ductility temperature (ZDT). The nature, shape, and size of precipitates have been investigated by TEM (JEM2100). Hot tensile test with low strain rate was simulated by Gleeble-1500. The objective of present study is to provide reference for zero defect of microalloyed steel during continuous casting process."

Jan 1, 2013

By Takahiro Furuzono

Saganoseki Smelter and Refinery of Pan Pacific Copper Co., Ltd. started treating copper anode slimes using a unique hydrometallurgical process in chloride media in 1997. The process comprises the following stages, decopperizing, wet chlorination, solvent extraction for gold, silver chloride reduction, and separate reduction stages that treat the gold extraction raffinate with sulfur dioxide gas. Precious metals and rare metals in the copper anode slimes are dissolved in an aqueous solution of hydrochloric acid by oxidative leaching, which is termed wet chlorination. Gold is efficiently extracted from the chlorination liquor by dibutyl carbitol in the solvent extraction stage. Gold is reduced by oxalic acid from goldloaded dibutyl carbitol and recovered as gold powder. The gold powder is cast directly into granules or ingots of more than 99.99% purity without electrorefining. Selenium is recovered as a selenium residue by reduction with sulfur dioxide gas and refined through vacuum distillation. The plant was designed to process 132 tonnes of copper anode slimes per month and has a current capacity of 206 tonnes per month due to several enhancements. Compared with the conventional process, the hydrometallurgical process described here provides some advantages, in particular, a higher product quality, shorter gold-retention time, and reduction in environmental load.

By Brandon R. Ball

An investigation of the effects of ozone and ozone-induced hydroxyl radical on reducing whole effluent toxicity is described and discussed relative to the application of ozone for industrial water treatment. Results from operation of an ozone system treating industrial effluent from a lead and zinc mine in Colorado are presented. The mine discharges 1,000 gpm of wastewater into a tributary of the Arkansas River and has historically exceeded Whole Effluent Toxicity (WET) limits and on occasion has exceeded numeric limits for copper, ammonia, and cyanide. Based on results of a Toxicity Identification Evaluation (TIE) conducted on the effluent and individual process waste streams, the source of effluent toxicity is believed to be primarily associated with organic reagents used in the milling process. Based on test results, an applied ozone to COD ratio of 3: 1 by weight and a contact time of 30 minutes was found to be effective for reducing whole effluent toxicity at pH 11 but not at pH 7, indicating oxidation by hydroxyl radical to be the dominant mechanism responsible for toxic-ity reduction. At an applied ozone to COD ratio of 3:1 and a pH of 11, toxicity was improved from 0 percent survival to 100 percent survival for Ceriodaphnia dubia and fathead minnow (Pimephales promelas) based

Jan 1, 1996

By K. S. Kawatra

In recent years, there have been several efforts to develop binder mixtures for iron ore pelletization. Some efforts have been fruitful, while others have encountered failure. For example, adding corn starch to bentonite is effective, while adding fly ash to bentonite is not. When binders are made with fly ash, a pozzolanic reaction occurs, but no such reaction occurs when bentonite and corn starch are used together. The authors analyzed which binders can be mixed, and which binders will succeed. The authors confirmed this analysis with several laboratory and plant studies. This paper presents this critical analysis, along with various combinations of binders for making Iron Ore Pellets.

By Stavros A. Argyropoulos, Michael Trovant, Norman J. Goudie

"Two studies were carried out to estimate the thermal resistance of various interfaces using experimental and computational techniques. Three types of interfaces were examined. The first study investigated metal-mold interfaces, and the second study focused on metal-metal and metal-oxide interfaces.For the metal-mold interface, the air gap size was measured and subsequently correlated with the interface thermal resistance. The procedural details are outlined for the development of a correlation which predicts thermal resistance as a function of air gap size.Investigation of the metal-metal and metal-oxide interfaces employed data from a series of experiments as input into a model, which solved the inverse heat conduction problem in terms of a resistance estimate. These experiments, involved dipping a cold cylindrical metal into a liquid metal or liquid oxide, respectively. Under these conditions, a shell freezes around the cylindrical addition and a thermal resistance develops during the time period which shell exists . The Heat Transfer Coefficient (HTC) at the addition shell interface differs significantly among the various types of metals and oxides used. In the case of an oxide shell, the (HTC) is about an order of magnitude lower than the (HTC) of the metal shell.INTRODUCTIONIn many metals processing operations there is a need to estimate the thermal resistance at metal-metal, metal-oxide, metal-mold interfaces. This need was further intensified with the recent proliferation of mathematical models, which predict various transport phenomena events. There are many factors which can influence the magnitude of the interfacial thermal resistance. Some of the factors, among others, are as follows: contact temperature, metal thermal conductivity, apparent contact pressure, surface roughness, interstitial gas conductivity, and interstitial gas pressure.In this paper, two studies are reported on the estimation of thermal resistance. The first involves, the development of heat transfer coefficient-air gap relationships at the metal-mold interfaces. The second includes, estimations of thermal resistance at the addition-shell interface. The former case is encountered in the metals solidification and the latter during the melting and/or dissolution of additions to liquid metals or slags."

Jan 1, 1999

By Bing Ji Yan, Cui Wang, Ya Peng Zhang, Chuan Hui Li, Hong Wei Guo, Jian Liang Zhang

There are a lot of research of the chlorine element’s influence on blast furnace, and mainly pay close attention to the harm to gas pipes and equipment. There are three kinds of chloride in the blast furnace gas, including HCl, NH4Cl, and NaCl (or KCl, ZnCl, etc.). This paper mainly analyzes all kinds of phenomenon of the chlorine element overflowing blast furnaces in Jinan Steel, and puts forward some different viewpoints, which are that the chloride overflowing out of blast furnace in the types of HCl, NH4Cl, or NaCl (KCl) not only has much to do with raw materials of chlorine load level, at the same time with the blast furnace burden distribution. On this basis, comes up with countermeasures for the different situation, such as adjusting the burden distribution matrix to guarantee the central gas flow smooth and changing the kind of raw materials to reduce the chlorine quantity, which will be helpful to prevent the harmful influence of chlorine element.

Mar 1, 2017

By Thomas J. O'Keefe, Pu Yu, George Houlachi, Xuewen Tang

"Impedance measurements were used to investigate the electrochemical characteristics of acidic zinc sulphate electrolytes containing Sb3+, gelatin and their mixtures. The data were correlated with cyclic voltammetry curves made using synthetic as well as industrial electrolytes. The cyclic voltammetry results were similar to those obtained in previous studies in that antimony caused a depolarizing effect while gelatin gave an increase in the potential for zinc nucleation on an aluminum substrate.The electrochemical impedance spectroscopy (ElS) evaluations were conducted on electrodeposited zinc at three overpotential values. The potentials were chosen to represent various current density regions in the zinc polarization curves. The antimony and gelatin gave characteristic impedance plots which correlated with expected behavior, particularly current efficiency. Both antimony and glue appear to modify the intermediate zinc reaction sequence, but in different ways. The data strongly suggest that film formation and stability are major factors in the zinc ion reduction mechanism.IntroductionThe zinc electrodeposition process is sensitive to the presence of a variety of organic and inorganic chemical species in the electrolyte [I]. Such components can produce either beneficial or harmful effects, depending on their relative concentrations and electrochemical behavior. Extensive investigations have been made to gain a better understanding of the changes occurring during zinc deposition in the presence of such additives. Techniques employed include microscopy, x-ray diffraction, dynamic voitammetry, current imd energy efficiency studies [2-5]. Ultimately, the objectives are to identify the factors which most affect the efficiency of the process and to provide a means to effectively control them.One of the most harmful impurities is antimony, which can be detrimental when present at concentrations as low as 10 to 20 parts per billion. Dramatic changes in zinc polarization behavior, deposition structure and current efficiency have been observed with antimony in the electrolyte. Antimony appears to lower the hydrogen overpotential by hydride formation or a similar catalytic mechanism, which allows an increase in localized corrosion and zinc dissolution [6-8]."

Jan 1, 1997

By Florian Kongoli

The production of a homogeneous self-fluxing sinter is an important step in iron making processes. A good sinter should have good permeability and reducibility and has to keep those characteristics for a certain time. An early melt down of the sinter in the blast furnace, where its solid state reduction is essential, would cause many problems such as low permeability and reductibility. Nevertheless, the important factors that influence these characteristics, such as the chemistry of the sinter and the fluxing effect during sintering and sinter reduction conditions have not yet been clarified. In today's new reality where many new minor components such as Al2O3 and MgO enter to the sinter through raw materials, the quantification of the fluxing effects during sintering becomes even more important. In this work, the liquidus surface and phase relations of the sinter primary melts in the CaO-FeO-Fe203-Si02 system at sintering conditions have been quantified. The fluxing effect of oxygen potential, Al2O3 and MgO has also been quantified by the means of some practical diagrams that can directly help the optimization of the sintering processes.

Jan 1, 2003

By Florian Kongoli

The production of a homogeneous self-fluxing sinter is an important step in iron making processes. A good sinler should have good permeability and reducibility and has to keep those characteristics for a certain time. An early melt down of the sinter in the blast furnace, where its solid state reduction is essential, would cause many problems such as low permeability and reductibility. Nevertheless, the important factors that influence these characteristics, such as the chemistry of the sinter and the fluxing effect during sintering and sinter reduction conditions have not yet been clarified, In today's new reality where many new minor components such as Al2O3 and MgO enter to the sinter through raw materials, the quantification of the fluxing effects during sintering becomes even more important. In this work, the liquidus surface and phase relations of the sinter primary melts in the CaO-FeO-Fe203-Si02 system at sintering conditions have been quantified. The fluxing effect of oxygen potential, Al2O3 and MgO has also been quantified by the means of some practical diagrams that can directly help the optimization of the sintering processes.

Jan 1, 2003