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By Mieke Campforts

The usefulness of the water-cooled probe technique to experimentally study slag solidification and freeze lining formation in pyrometallurgical reactors is evaluated. With this technique a layer of solidified slag is formed on a water-cooled probe that is submerged into a liquid slag bath. The influence of the submergence time and the heat input is examined. The solidified layers are analyzed with light microscopy, electron microscopy, electron probe micro-analysis and X-ray diffraction. Thermodynamic software is used to interpret the solidification microstructure. The results demonstrate that the technique is useful to understand freeze lining formation.

Jan 1, 2006

By Jing Zhong, Yugang Li, Chen Yan, Shaoda Zhang, Qian Wang

Online surface quenching technology has been developed for the hot charging process to prevent the surface cracks in high strength low-alloy steel slabs. In this paper, a two-dimensional heat transfer model of surface quenching process was presented. This finite element model includes nonlinear thermodynamic properties, by which the slab temperature distributions were computed. The model predicted temperatures show reasonable agreement with the measurements. The effects of the water flow rate and slab movement velocity on temperature variation during the quenching and subsequent tempering process were investigated. The result shows that the temperature drop increases but the tempering temperature changes slightly with increasing water flow rate and decreasing slab velocity. Keeping the slab movement velocity at 1.2-2.1m/min and the water flow rate at 55-70m3/h, the slab surface experiences a temperature drop of 400-600 firstly, then recovers above 650, the quenching and energy-saving effect are remarkable.

Jan 1, 2015

By Damien Wagner

To reduce the emission of greenhouse gases by the steel industry, particularly for ironmaking, the production of DRI (Direct Reduced Iron) using hydrogen as the reducing gas instead of carbon monoxide is being considered. In this context, the reduction of pure hematite by hydrogen was studied at the laboratory scale, varying the experimental conditions and observing the rate and the course of the reaction. All the reduction experiments were performed in a thermobalance and supplementary characterization methods were used like scanning and transmission electron microscopy, X-ray diffraction, and Mössbauer spectrometry. The influence of rising temperature in the range 550-900°C is to accelerate the reaction; no slowing down was observed, contrary to some literature conclusions. A series of experiments consisted in interrupting the runs before complete conversion, thus enabling the characterization of partially reduced samples. Interpretation confirms the occurrence of three successive and rather separate reduction steps, through magnetite and wustite to iron, and illustrates a clear structural evolution of the samples. Finally, the influence of the sample type was revealed comparing a regular powder, a nanopowder and a sintered sample. The regular powder proved to be the most reactive despite its larger grain size, due to a more porous final structure.

Jan 1, 2006

By Guo Chen, Jin Chen, Jinhui Peng

In this paper, solving common problem of electrostatic precipitator (ESP), which was frequently ruptured of the cathode insulation in the production process were studied. The microwave heating airflow technology was introduced, which takes full advantage of its unique properties, solves the output problem of the high temperature air, achieves purpose of energy conservation, important economic significance and environmental significance. The mathematical models and designing of microwave high-temperature hot air system was calculated. The common forms of heat exchangers and comparative analysis were also introduced. The conditions found to be at the temperature of 240 °C. Under optimum conditions, the microwave heating power was 1482 W. Based on the mention results, this microwave heating method can be applied effectively and efficiently way for the production process of electrostatic precipitator.

Jan 1, 2015

By Leonid M. Lerner

High temperature aluminum Alloy 8009 is a rapidly solidified/powder metallurgy aluminum-iron-vanadium-silicon alloy. This alloy in combination with hard oxide aluminum film has unique engineering properties which may recommend its use in compressors and impellers for aerospace applications. Various anodizing processes (including Sanford Low Voltage DC+AC Process) for these task will be evaluated and normal chemical composition, physical properties, and macrostructures of 8XXX aluminum alloys will be presented.

Jan 1, 2006

By Leiv Kolbeinsen, Stian Seim, In-ho Jung

"The current work presents new experimental data in the iron-unsaturated region of the FeTiO3-Ti2O3-TiO2 slag system. The samples are prepared by melting pure reactants in a high frequency induction furnace that employs a cold crucible. A similar experimental set-up has been described in literature and proven suitable to investigate high titania slags. The FeO content of the samples range from 3.7 to 21.8 wt% and the Ti2O3 content range from 3.6 to 30.1 wt%. The liquidus temperatures of the samples are measured in-situ by a spectropyrometer and range from 1450 to 1645 °C.In addition, an improved thermodynamic database for the FeO-Ti2O3-TiO2 system has been developed. Ternary parameters have been included and optimized to fit previously published experimental data. This optimization minimizes the discrepancy between experimental data and thermodynamic calculations as previously discussed in literature. New liquidus projection plots are proposed for the FeO-Ti2O3-TiO2 and the FeTiO3-Ti2O3-TiO2 systems.IntroductionIlmenite (FeTiOs) smelting is a relatively small industry world-wide. However, a reasonable focus on the process has been applied in Norway due to the location of one such smelter in Tyssedal, which is located in the western part of Norway. The process is essentially carbothermal reduction, where most of the iron in the ilmenite is reduced to its metallic state, and the titanium oxide is concentrated in the slag product. The metallic iron is sold as a high purity pig iron and finds applications in cast products. The slag concentrate is further processed for the production of TiOvpigment and/or titanium metal. This further processing can be performed through different routes according to the purity of the slag concentrate."

Jan 1, 2012

By Norihiro Murayama

The hydrothermal syntheses of zeolites from coal fly ash were carried out using NaOH and KOH as an alkali source. The cation exchange capacity (CEC) and the ion exchange selectivity were investigated for the zeolites synthesized by a hydrothermal treatment. The effective usage of the zeolite as a cation exchanger was considered from the viewpoint of engineering. Zeolite P, HS (hydroxysodalite) and K-CHA (potassium-chabazite) are mainly formed as zeolite species in NaOH or KOH solution at 393K. The zeolite P and K-CHA have a large exchange capacity as a cation exchanger. The cation exchange isotherms of various monovalent and divalent cations with various zeolites are investigated. The order of selectivity of the zeolites is as follows, NH4+> K+> Li+.For the divalent cation, the largest removal amount is obtained for Pb2+ in the low equilibrium concentrations below 0.2mmol/dm3, and almost perfect removal can be achieved for Pd2+. The order of selectivity of zeolites in low concentration is expressed in the following order; Pb2+> Co2+> Cd2+> Ca2+> Mg2+> Ni2+. Ii is considered the zeolites obtained from coal fly ash can be used as an excellent cation exchanger.

Jan 1, 2006

By Basak Anameric

Pig iron nugget process was developed by Kobe Steel as an environmentally friendlier, economical alternative to traditional blast furnace process. The process aimed to produce highly metallized, slag free pig iron nuggets throughout a single stage heat treatment, utilizing coal as a reducing ? carburizing agent. The objective of this work was to determine whether the pig iron nuggets produced at the laboratory conditions had comparable physical and chemical properties with the blast furnace pig iron. The physical and chemical properties of the pig iron nuggets were determined utilizing x-ray fluorescence spectroscopy, x-ray diffraction, optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and apparent density measurements. The pig iron nuggets had similar chemical composition and apparent density values (6.7 ? 7 g/cm3) with blast furnace pig iron and they had microstructures similar to low carbon white cast iron. These properties make them a competitive alternative to blast furnace pig iron.

Jan 1, 2006

By Dinesh Agrawal

Microwave energy has been in use for variety of applications for over 50 years. These applications include communication, food processing, wood drying, rubber vulcanization, medical therapy, polymers, etc. In the last two decades microwave heating has been also applied very effectively and efficiently to heat and sinter ceramic materials. Microwave heating is recognized for its various advantages, such as: time and energy saving, very rapid heating rates, considerably reduced processing cycle time and temperature, fine microstructures and improved mechanical properties, better product performance, etc. The most recent application of microwaves has been in the field of metallic materials for sintering, brazing/joining and melting. Several common steel compositions, pure metals and refractory metals have been sintered in microwaves to nearly full density with improved mechanical properties. Many commercial powder-metal components of various alloy compositions including iron and steel, copper, aluminum, nickel, Mo, Co, Ti, W, Sn, etc., and their alloys have also been sintered in microwaves producing better properties than their conventional counterparts by using a 2.45 GHz multimode microwave system. This work has been further extended to join and braze bulk metal pieces, especially super alloy based turbine blades. Further, in a specially designed microwave cavity, even the bulk metals can be made to couple with the microwave field and melted. The implications of these findings are obvious in the field of powder metal technology.

Jan 1, 2006

By Peter Brown

The present work involves the study of Chemical Vapor Deposition (CVD) of silicon carbide from the methyltrichlorosilane (MTS) - hydrogen system. A computer program, SOLGASMIX has been employed to calculate the equilibrium compositions of the gaseous and condensed phases in the MTS - H2 system. The results indicate the range of parameters such as temperature, pressure and species concentrations, required to deposit the single phase Sic under thermodynamic equilibrium conditions. A mathematical model for describing the transport phenomena and the rate of deposition of Sic onto a thin rod in a vertically-oriented hot-walled CVD reactor has been developed. Exper iments were conducted using the same operating conditions as those used in the model in order to validate the mathematical predictions. The predicted rates of deposition were found to be in good agreement with those obtained experimentally. The model can be used to study the effects of various operating parameters on the rate of Sic deposition on a fiber.

Jan 1, 1992

By Francis Vanbellen

Umicore Precious Metals Refining operates an integrated precious metals smelting and refining plant in Hoboken, Belgium. Once a smelter and refiner of complex concentrates, the plant today?s feed consists exclusively of industrial and consumer recycled products, making it the world?s largest recycling facility for precious metals. Unlike the fairy tale of the Frog Prince, it took much more than a princess? kiss to successfully realize this makeover. A completely renewed plant has been built over the past decade.

Jan 1, 2006

By Wentao Guo, Xuefeng She, Qingguo Xue, Jingsong Wang

By the coke gasified reaction device and online measurement high-temperature compressive strength apparatus, the variation of pore structures of coke after gasified reaction with CO2 and H2O was investigated. Research illuminating the influences of solution loss rate, temperature, and carbon species on compressive strength of coke was also carried out. The results showed that the total compressive strength was higher than for the reaction with CO2. The high-temperature compressive strength of coke decreased with the increasing of solution loss ratio or temperature after reacting with CO2 and H2O. At the same solution loss ratio, the damage of pore structure to coke strength after gasified reaction with H2O was relatively smaller and the deformation resistance was stronger when compared with that in CO2.

Jan 1, 2016

By Sung-Joo Lee, Gi-Chon Han, Nam-Il Um, Hee-Chan Cho

"In Korea, almost all of bottom ash produced by coal power plants is disposed of in ash ponds. Ash storage areas comprise more than 80% of most coal power plant sites. This disposal method is causing environmental problems and a managerial burden for plant operators. In this study, investigations to develop a beneficiation process for separating coal pond ash into various products were undertaken. To improve efficiency of the separation, coal ash was separated by sizes and each size fraction was subject to various beneficiation processes. The separation process used were flotation (-200 mesh size), hindered settling (16x200) and tabling (16x200 and 8x16 mesh). The results showed that various marketable products, such as lightweight aggregate, sand, high-carbon fuel, could be recovered from coal pond ash using simple physical separation techniques.IntroductionDue to the increased use of coals every year, about fifty million ton of coals were used in 2007 alone. As a result, about 6 million tons of coal ash were generated. In Korea, the coal bottom ash is classified as a general industrial waste and is usually disposed of in ash ponds. The costs for this disposal method continue to increase due to rising costs of site management and development and more strict environmental regulation. Therefore, utilities are constantly looking for ways to increase utilization of coal ash. In this study, various beneficiation processes were evaluated to examine the possibility of separating coal pond ash into various products which can be used as aggregates and high-carbon fuel."

Jan 1, 2008

By Carla Lupi

In this work, nickel-cobalt electrodeposition under galvanostatic conditions was investigated. Ni-Co alloy was electrowon from an acid sulphate bath containing 40 g/L Ni and2-8 g/L Co.. The effect of electrolyte composition, current density, temperature, solution pH and presence of buffers such as H3BO3 and (NH4)2SO4 on Co content of the binary alloy has been investigated. In particular, current densities ranging from 180 to 400 A/m2 and temperatures ranging from 27 to 60°C were tested. The composition of Ni-Co alloys may be diversified through the selection of process parameters. The experiments show that the highest cobalt content of the alloy is reached by using a buffer free electrolyte without solution pH control. Though, in these conditions, the most homogeneous, fine and regular deposit morphology is obtained, energy requirements are the highest in tests lasting just two hours.

Jan 1, 2003

By Kalathur S. Narasimhan

Powder metallurgy is a net shape process competing favorably with machining, stamping, forging and castings. The growth of ferrous powder metallurgy over the past four decades reflect the advancements in materials technology, compaction technology, sintering technologies and other related fields. This presentation gives a brief background on how materials technology evolved.

Jan 1, 2006

By Greg Dowling, Jun Ge, George Shannon, Shufeng Yang, Yongfeng Chen, Lifeng Zhang

"Inclusions in 316L stainless steel ingots poured using two different upgate designs – a traditional upgate and a swirl upgate - were investigated using SEM and ASPEX automated inclusion analysis. The main inclusions were high SiO2 inclusions, MnS inclusions and SiO2-Al2O3-CaO inclusions. More inclusions were detected at the top of the ingot than other places in vertical direction, and more inclusions were at the edge of the ingot than other place in the radial direction. With swirling upgate there were more K- and Na- bearing inclusions than that with the traditional upgate indicating possible more serious flux entrainment with the swirl upgate.IntroductionIngot casting still is very important for production of special steel grades including high carbon chromium bearing steel, thick plate, seamless tube, forgings, bars, and wire rods [1] . During the bottom teeming process, molten steel enters the trumpet and passes through the spider into the runners. Molten steel then enters the ingot mold through an upgate near the end of the runner. In the early stages of filling a mold, a mold flux bag hung in the mold were burnt and the mold flux will cover the top of the rising steel to protect the steel from being reoxidized, acting as well as act as a thermal insulator. So far, some efforts on studying inclusions characteristics in the ingot have been reported. A review paper on the control of inclusions during steel ingot casting was published by Zhang et al. [2] Zhang also studied Inclusions in bottom-teemed ingots of plain carbon steel and found that the >20µm inclusions originated from either the entrainment of mold flux of the reoxidation during teeming process. [3] The results of Nagendra and Du showed that there were more inclusions in the centre part of the ingot [4]. Eriksson et al reported that the composition of inclusions was more complex in the mold samples in comparison to the ladle samples, and more inclusions in the mold were found than in ladle because of the reaction between the mold flux and the molten steel [5]. It was reported that SiO2-CaO-Al2O3 inclusions originating from mold powder with reoxidation product Al2O3 as a part, and there were more inclusions close to the side wall than the center of the ingot in the radial direction. [6]. A more recent investigation showed that four main types of inclusions in runner samples were classified: oxides, sulfides, complex and carbon-nitrides. [7] The flow pattern in the mold during filling has been found to be an important factor regarding inclusions in the ingot. In the early stages offilling a mold, steel enters the mold through the entry nozzle at a high velocity. The effect of the resulting turbulence on the meniscus can lead to the entrainment of mold flux. Efforts have been paid over the years to find methods to reduce the velocity of the molten steel entering the mold, such as using opening angle of the inlet nozzle [8], using swirl blade at the runner [9], using a divergent nozzle combined with a swirling flow generated in the nozzle [10-11]."

Jan 1, 2012

By A. M. Strachan

The arising and behavioural pattern of polonium-210 in the Capper Pass & Son Limited non-ferrous metal smelting and refining circuit is briefly discussed. The process developed for the removal of polonium from lead, solder and bismuth is discussed in detail, together with the essential personnel safety and environmental protection precautions which must be taken during the refining and subsequent storage of the active dross.

Jan 1, 1992

By Lifeng Zhang

The transport of fluid, heat and particles (bubbles and solid inclusions) in flowing molten steel is investigated in steel refining ladles, the continuous casting tundish, continuous casting mold and strand, and steel ingot casting processes. Inclusion removal from the molten steel by flow transport and bubble flotation, and inclusion growth by collision and diffusion are discussed. Removal of impurity elements such as [C] and [O] during steel refining are reported.

Jan 1, 2006

By Andreas Weber

Batrec operates a plant for the recycling of used dry batteries with a capacity of 3000 tons per year. The plant Is situated In a tourist area of Switzerland and has complied with all the strict emission restrictions. The process yields four products: FeMn. Zn, Hg and slag. No hazardous waste Is produced. All types of batteries can be treated.

Jan 1, 1995

By Fatma Arslan

The lateritic nickel ore sample subjected to this experimental study was taken from Çalda ore deposit (Turkey) and contains 1.43% Ni and 0.105% Co. Mineralogical investigations showed that the ore sample contains asbolane, chromite, limonite, hematite, goethite, lepidocrocite, magnetite, serpentine, and clay type minerals together with chalcedon, quartz, calcite, and chlorite. In the acidic leaching experiments, the effects of temperature, acid (H2SO4) concentration, and leaching time on nickel leaching recoveries were investigated. Leaching recovery versus time curves showed a parabolic trend and increasing the temperature shifted that curves to the higher values. The dissolution of nickel from lateritic ore can be explained by a shrinking core model and the apparent activation energy was found as 47.34 kJ/mol in the range given by the literature. The highest Ni and Co leaching efficiencies as 90.2% and 96.8% respectively were obtained at 80°C temperature, 200 g/L H2SO4 concentration, and 8 hours of leaching time.

Jan 1, 2006