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By Okechukwu Anopuo, Gerhard Tober, Petra Maier

"In this study, an investigation on the microstructure of hot rolled steel S355J2+N was conducted to optimize process parameters of complex forming, which combines rolling and bending. The best sets of parameters are worked out based on homogeneous mechanical properties and microstructure within the varied deformation degree with maximum at <p = 1.14 on a 25 mm thick plates. Mechanical properties, especially of heavy plates, are strongly influenced by the local deformation degree, strain rate and temperature. Detailed microstructural analyses showed that the ferrite-pearlite band structure changes near the surface, while maintaining homogeneous microstructure within the deformed work piece. Surface decarburization was also observed and this leads to decrease in hardness. To minimize iron oxide formation which could lead to side cracking, reduction in exposure time to temperature was suggested. On the other hand, temperature reduction below a critical value would risk the accurate forming process.IntroductionThis work presents the preliminary results of research to develop a new complex deformation process of thick steel plates. Complexity is given because the forming process combines rolling to reduce thickness and profiling by bending. The work piece will experience a thickness reduction from 25mm to 8 mm and is double curved. To explain and understand forming of thick plates basics of sheet forming as well as massive forming need to be used. At the moment there is no forming process established to produce double curved plates including reducing thickness in one process step. Technologies nowadays consist of two process steps: flat rolling and pressing in shape. Due to good weldability and formability the final product will be made of steel S355J2+N. This low-carbon steel is well understood and has a low strengthening exponent, which is expected to keep the forming forces down. Reduction of thickness from 25 mm to 8 mm gives furthermore a high deformation degree. Thus, hot forming has to be applied. The determination of process parameters is the main aim of overall research project; temperatures above lOOO°C are expected. Flow curves in literature are given at various temperatures and strain rates [1]. However, experiments with data close to the industrial application are rarely found, especially at low strain rates and high deformation degrees. Pre-test were done by flat rolling, being aware that the influence of bending is eliminated. The microstructure evolution were characterised in relationship to material formability with special attention to grain size change and recrystallization. Representative samples should be selected from specific locations in the deformation zone according to the knowledge about the metal forming process [2]. Due to no further alloying elements in S355, no precipitation hardening is expected to take place during hot forming, which keeps the mechanisms simple and the concentration on the feasibility of the complex forming process is given."

Jan 1, 2012

By Akita Ito, Sumio Kato, Mikio Sugai, Shinichi Nakata

"Spark Plasma Sintering (SPS) is a newly developed method for the sintering of metal and ceramic powders, and completes their densification at low temperature and in short period. The SiC powder was synthesized from diatomite and graphite or carbon black by heating at 1 450°C for 1 hr in an argon atmosphere. The synthesized SiC powder was heated at 1500-1800°C, 50 MPa for 15-18 min by SPS. The relative density of sintered SiC body increased with the rise in the temperature. The oxidation of the surface of the SiC particle and impurities in SiC from diatomite greatly influenced the sintering promotion of SPS.IntroductionThe SiC has high hardness because of the covalent bonding, and is also excellent in thermal and chemical stability. However, it is difficult to obtain a dense SiC sintered body by the combustion heating-method. Therefore, the dense SiC bodies have been made by the use of additives and I or the hot pressing (HP) method.In this study, the SiC powder was synthesized by using diatomite of natural products and graphite, and carbon black of reagent as raw materials, and the relationship between the properties of SiC powders prepared at various synthetic conditions and the density of sintered body by SPS was examined."

Jan 1, 2000

By Jakub Kaczorowski

In the production of Mn-alloys, the Boudouard reaction significantly influences the mass and energy balance. The endothermic nature of this reaction requires more energy for the process, while the direct consumption of carbon is reflected in the greater demand for carbonaceous raw materials. Therefore, it is desirable to eliminate or suppress the reaction. The kinetics of the Boudouard reaction are a function of many factors, of which coke properties and the conditions around the particles (i.e. temperature, gas composition) seem to be the most important. In the present study properties of selected single source and commercial metallurgical cokes are compared with reactivity results. The single source cokes represent a single coal that has been carbonized in a laboratory scale furnace. The commercial cokes are products of carbonization of coal blends under industrial conditions. The coke properties include proximate, ultimate and ash analysis. Also, coke petrography with carbon forms is included. The reactivity tests were performed on different particle sizes at various temperatures, gas compositions and gas flow rates. The experimental parameters were chosen to simulate the conditions in an industrial furnace. The results show that highly graphitized structure of cokes, minimal surface area and a low concentration of ash retard the reactivity. Of the other factors, the temperature and the gas composition have the greatest impact on the reactivity.

Jan 1, 2006

By David J. Roha

"The harsh environment of the Carbothermic Aluminum process makes necessary numerical modeling as a means of process visualization and understanding. A brief survey of the various numerical models, with emphasis on CFD, applied in the development of the process is presented.IntroductionThe environment of the Alcoa Carbothermic reactor is necessarily a harsh one, with temperatures approaching 2100 °C and plenty of reactive dust and vapors. As such, it is difficult to directly observe what is actually taking place. Thermocouples can last for a few minutes but are eventually destroyed. The openings to optical pyrometers become occluded with dust and condensation. Graphite sheathing embrittles, reacts away or becomes clogged with condensate. Dip-samples on steel rods are routinely taken, but their interpretation is often unclear.Those measurements that can be reliably taken are invaluable, but often do not provide a complete picture. Therefore from the very inception of the project both physical and computer based models have played an important role. Modeling provides an intuitive understanding of the processes that might be taking place and in very many cases approach quantitative prediction. I will briefly touch upon computer-based modeling performed at Alcoa over 12 years of the Carbothermic project, with special emphasis on CFD. The explanation of physical models is perhaps best left for those with the greatest familiarity with them"

Jan 1, 2012

By John Sakala, Jeyapandian Sasikumar, Sydney Kwalela

The Isasmelt Furnace was commissioned in September 2006 with a concentrates treatment capacity of 850,000 tonnes per annum. However, the converter section became a bottleneck to the high throughput. Over 25% of the Isasmelt Furnace down time was attributed to lack of converter space. Factors that affected converter operations were low tuyere line campaign life (an average of 150 blows), high reverts generation, low conversion rates, and high converter cycle time. As a result of efforts carried out to improve converter operation, the average campaign life has increased to over 250 blows and reverts generation has been reduced from 22% of concentrate treated to 15%. Blister copper conversion rate has increased from 15 tonnes per hour to 19 tonnes per hour and blowing time per cycle has been reduced from 5.7 hours to 4.7 hours.

Jan 1, 2012

By Kenneth L. Reid

The Mineral Resources Research Center at the University of Minnesota has recently installed a QEM*SEM system (Quantitative E.valuation of Materials using Scanning Electron Microscopy) to aid in detailed mineralogical evaluation of potential mineral resource developments in Minnesota and to provide services to the North American mineral industry. A primary application for the unit is to serve the Minnesota taconite industry by providing mineralogical analysis of ores and concentrator products. Minnesota taconite ores contain fine-grained magnetite in a quartz matrix. The ores undergo several size-reduction/magnetic-separation steps to produce a final concentrate with approximately 75% passing 325 mesh and containing about 5% gangue. The paper describes a typical taconite concentrator flowsheet and reports some preliminary results of the applications of QEM*SEM particle image maps and cumulative yield liberation data to samples from selected points in the concentrator circuit.

Jan 1, 1988

By Jong-Oh Jo1

Thermodynamics of Ti, N and O in liquid iron was studied in order to establish a data base for the prediction of TiN and TiOx formation in liquid stainless steels containing various alloying elements including Cr, Ni and Si as a function of temperature. The interaction parameters of these elements on Ti and N were determined using the metal-nitride-gas equilibration technique. The TiN stability diagram for a commercial stainless steel grade was constructed from the measured thermodynamic parameters, and its validity was confirmed experimentally. The interaction parameters between Ti and O, and the equilibrium constants for Ti deoxidation reactions for the formation of Ti2O3 and Ti3O5 were also determined by the equilibration of the melts with those oxides identified by the XRD and the EPMA analyses.

Jan 1, 2006

By B. Fresz

Before aluminum is utilized in automotive bodies, the longevity of the electrodes employed in the resistance spot welding of aluminum must increase. This paper explores the affects of electrode composition on electrode life. To compare these variables, electrode tests were completed on a Taylor Wield welding machine using, Cu-Cr, Cu- Zr, Cu-Cr-Zr, Cu-Be, and Glidcop electrodes tested to 12.5%, 25%, 50%, 100%, and 150% lifetimes. Electrode diameters were found via a magnification technique using a PULNIM video camera attached to a low magnification Wild Heerbrugg stereo-zoom microscope. From these measurements, graphs of electrode life verses face diameter and weld number verses face diameter were created. Analyses of these graphs suggest that a single failure mechanism is responsible for electrode failure, though the number of welds until failure (100% electrode life) varied with composition (700-2000 welds).

Jan 1, 1999

By S. Ikenobu

This paper describes a method for processing high-silicate zinc concentrates by hydrometallurgical zinc refining. Silica in concentrates reacts to form zinc silicate during roasting. The zinc silicate readily dissolves and slowly precipitates in sulfuric acid solutions during leaching. However, if proper operating parameters are not maintained, the colloidal silica may form an unfilterable gel. That is, according to the investigation results obtained, the silica concentration in the reactor has to be maintained at 5 g/1 or less (preferably 2 g/1 or less) by promoting the precipitation reaction. The proposed method has made it possible to precipitate silica in a form having excellent solid-liquid separation characteristics, without the need for facilities having a high filtration capacity, and to maintain a low silica concentration in the reactor by feeding a composition containing pre-adjusted silica contents.

Jan 1, 2000

By Alex I. Kociubczyk, Wilky Desrosin, Lucía Mabel Boycho, Alicia E. Ares, Carlos E. Schvezov

In the present research, commercially pure Sn and Zn, and Sn-Zn alloys (Sn-1wt.%Zn, Sn- 2wt.%Zn, Sn-4wt.%Zn, Sn-8wt.%Zn and Sn-8.9wt.%Zn, weight percent) were obtained by a horizontal directional solidification process with two opposite senses and heat extraction. The solidification process was realized using a horizontal furnace with two heat extraction systems at both ends. The temperature was measured using eight K-type thermocouples and an electronic recorder of temperature data. The resulting structures were analyzed using optical microscopy. From the solidification process the thermal and metallographic parameters were determined in all samples. The presence of defects in the solidified pieces was observed. Internal defects pretended to be dependent not only on the composition of the alloys under consideration but also on the size of the structures formed, also, on the velocities and accelerations of interphases, and on the variation of thermal gradients. A model of the phenomenon from the first principles is presented.

Jan 1, 2015

By Takeshi Yoshikawa

For the sake of effective control of titanium-compound inclusions in the steel-making processes, especially for stainless steel production, the influences of alloying elements of chromium, nickel, manganese, molybdenum, copper and oxygen on the thermodynamic property of titanium in molten iron were investigated at 1873K. At a certain titanium potential controlled by the coexistence of Ti3O5 and Ti2O3 doubly saturation of steels, the interaction parameters between alloying elements and titanium in molten iron were determined as follows. [ ] From the investigations on the equilibrium of titanium deoxidation in molten iron, the activity coefficient of titanium and the first order interaction parameter between oxygen and titanium were determined as follows. [ ] Also, deoxidation equilibrium for titanium in molten 304 stainless steel was measured and compared with the calculated results using the determined interaction parameters.

Jan 1, 2006

By A. Mejias, M. A. Garcia, G. Diaz

During 1997 and 1998 two successful zinc feasibility studies, Skorpion and Sanyati, were carried out by Tecnicas Reunidas based on the modified ZINCEX® technology. The technical viability of each project was proved during more than 600 h of continuous running in a pilot plant. The Skorpion zinc project would recover 150,000 t SHG Zn/y from an oxidized zinc ore of a Namibian mine. The economical study showed that the plant would have the lowest production costs in the world. The Sanyati zinc project would treat a bleed from an existing copper refinery in Zimbabwe to recover 5,000 t SHG Zn/y. In the first case the electrowinning cellhouse was supplied by Union Miniere and in the second by Tecnicas Reunidas. This article highlights the pilot plant results and the advantages of the proposed process over conventional zinc production practices.

Jan 1, 2000

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

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

Jan 1, 2014

By J. Miernik, D. Krupka, B. Ochab

The electrolytic zinc plant, with a capacity 75,000 tonnes per year, is part of Zaklady Gorniczo-Hutnicze BOLESLAW. It is the biggest zinc producer in Poland. The electrolytic zinc plant started up in 1955 with a capacity 15,000 tonnes per year, and multiplied its production by 5 till nowadays. At the beginning, the plant processed only calcine from zinc oxides (60% Zn, 3-4% Pb, 0,03 % Cd) which were produced from Waeltz fumes by calcination in a rotary kiln. Participation of calcine from zinc sulfide concentrates in the feed grew during the BOLESLAW plant expansion. Currently, only roasted sulphide concentrates, calcine from fluid-bed roasters, is processed. This paper presents a general description of the ZGH BOLESLAW plant and discusses the processes of roasting, leaching, purification and electrolysis. Also shown are the chemical analyses of the various process materials.

Jan 1, 2000

By Daoxin Wu

Originated from(C4H9O)4Ti, nano--rutile TiO2 was synthesized by low temperature hydrolysis process in this paper. After being prepared by decomposing ammonium tungstate and covering on the surface of TiO2, TiO2/WO3 were characterized by means of X-ray diffraction(XRD), UV--vis difuse reflectance(DRS), fluorescence spectrum (FS). Results showed that with the increase of the supported concentration of WO3, the reflectance of DRS and the fluorescence spectrum intensity of TiO2/WO3 decreased accordingly, which indicated the powder?s increase in light absorbance and the decrease in luminescence respectively; with the increase of calcined temperature, the reflectance of DRS increased.

Jan 1, 2009

By Michael E. Stout

The recovery of the constituent components of spent lead acid batteries was pioneered in the early 1970&apos;s by M.A. Industries, Inc. MA&apos;s main reason for research and development in this area was to recover the polypropylene casings for use as feed stock in their injection molding plants. At that time spent and reject casings were either disposed of or being fed with the lead &apos;bearing materials into the ,smelting process. M.A. has since developed, built and operated plant for the conversion of scrap casing into reusable copolymer resins. The system is composed, of washing, .sizing, extrusion and pelletizing the polymer into a form which is ready to be injection molded into new products.

Jan 1, 1995

By Y. Sako, E. Nomura, K. Muraguchi, K. Shibata

In 1998, Mitsui Mining & Smelting Co., Ltd. (MMS) produced 70,000 tonnes of lead, 231,000 tonnes of zinc and 214,000 tonnes of copper. MESCO, Inc. has been in charge of the automation and mechanization of smelting facilities promoted by MMS as well as the construction of facilities for chemical production and electronics materials plants, by which MESCO has contributed to the development of MMS. Initially, MESCO developed a casting machine for refined lead in the early 1960's, and thereafter, it developed a casting machine for refined zinc, a stripping machine for zinc tankhouses and energy saving facilities. In the field of copper smelting, it has also developed automation and mechanization facilities.

Jan 1, 2000

By Alexander V. Suvorin, Vladyslav M. Sokolov

"The traditional technologies for production of the coprecipitated and deposited catalysts are analyzed from the standpoint of diversion of application of the feedstock and increase of efficiency for its usage. The options for return of the metals of spent catalysts to the catalysts production are described. The novel environmentally friendly and cost efficient approach for reutilization of the spent catalysts is realized in practice. It anticipates application along with spent catalysts of the waste generated in the catalytic productions. Reutilization of the Ni-containing catalysts is referred as an illustration. Introduction The recent development of large catalytic manufacturing for organic and inorganic synthesis, and petroleum refinery as well as for applied environmental catalysis has brought about increase and diversification of catalysts production. The generation of spent catalysts has been increased correspondently. The feedstock for production of catalysts is mostly metals in a form of nitrates, carbonates, hydroxides, hydroxydcarbonates. Sometimes salts of organic acids, of ammoniates, of chlorides and of sulphates occur. All these materials are scarce and expensive. So their repeated use by reutilization of spent catalysts is very actual issue. The traditional recycling the Fe-, Cr-, Ni-, Cu- or Zn-containing spent catalysts are carried out by pyrometallurgical reclamation of pure metals or alloys. They can not be used directly in production of catalysts [1, 2]. The hydrometallurgical approach is used for recycling spent catalysts with PGM, W, Mo, Co, Ni or Cu. It provides production of salts of these metals in a form of sulphates, chlorides, carbonates, hydroxydcarbonates and sometimes nitrates or ammoniates. Only a limited number of these salts can be used directly in production of catalysts. Material losses during catalysts production The basic feedstock for manufacturing coprecipitated and deposited catalysts that may be produced from the spent catalysts is aqueous solutions of metals nitrates. Their production is based on application of nitric acid as a dissolvent. About half of it is lost with the flue gases in a form of nitrates vapor and nitrogen oxides (II, IV). The last compound is generated by reaction:"

Jan 1, 2008

By Per Anders Eidem, Merete Tangstad, Jens Davidsen

"During excavations of submerged arc furnaces producing silicomanganese, silicon carbide (SiC) has been found. Contributing to the size of the inactive area of the furnace, the active area of the furnace where reactions occur will decrease, thus reducing the potential for pre-reduction in the furnace.This work studied the formation of SiC from the liquid-solid reaction between slag, metal, and metallurgical coke. Slags and metals with different levels of silica (S1O2) and silicon (Si) have been studied. The slag and metal has been heated together with coke, and the samples investigated by microprobe. The results show that SiC was formed on the coke particle through reactions with both slag and metal. For the metal, the carbon most likely diffused through the SiC to react with Si in the alloy. SiC formation with slag is likely to go through the reduction of Si02 to Si.IntroductionToday, Silicomanganese (SiMn) is produced in submerged arc furnaces (SAF) by reduction of S1O2 and manganese oxides, mainly with metallurgical cokes. Typically, the tapped metal has a silicon content of 17 - 20 wt.%. To achieve higher levels of Si, the metal can be refined by adding off-grade silicon metal, yielding low carbon SiMn. [1]. What is believed to be SiC that has been found during dig-outs of SiMn furnaces producing high silicon alloy. It is possible that excess amounts of SiC in the furnace cause operational problems, since SiC will occupy furnace volume. As SiC accumulates, the active volume of the furnace will decrease, increasing the flow of material and gas in the active areas of the furnace. Formation of SiC is inevitable, so it is desired to keep the formation as low as possible. To be able to control the formation of SiC, one has to understand the basic mechanisms."

Jan 1, 2012

By Kouji Mimura, Masahito Uchikoshi, Minoru Isshiki

"HfO2 is expected to be a gate dielectric used in ULSI alternatives to S1O2. Although the materials used in ULSI are required to be significantly pure, commercial Hf contains > 2 mass% Zr. It is important to establish a process for removing Zr from Hf. In the present study, anion-exchange separation using a multi-column method was employed. The separation tests were carried out at variety of temperatures and flow rates. The decrease in the flow rate of the mobile phase made the elution curves of both Hf(IV) and Zr(IV) broaden contrary to the case of Co(II), Cu(II), or Fe(III). This is caused by the difference in adsorption rate on the anion exchange resin. In addition, more than one column was connected in series in order to enhance the separation. As a result, the content of Zr(IV) was successfully reduced to 1/100 of that relative to the raw material.IntroductionHafnium is one of the most important materials in modem society. The main applications of Hf metal are as a control rod in a nuclear reactors because of its large neutron-capture cross-section and as an additive to various alloys because of its corrosion resistance [1]. In addition to those applications, attention has been recently paid to HfCh as a high-x"" dielectric used in ultra large scale integration, ULSI, as well as ZrCh, AI2O3 and La2C>3, which are expected to be alternatives to conventional S1O2 thin films [2].The materials used in ULSI are required to have a high purity in order to avoid unexpected errors due to impurities. Furthermore, high purity Hf is indispensable for investigating the intrinsic properties of Hf metal. Thus, it is significant to establish the purification process for Hf from both the industrial and academic perspectives."

Jan 1, 2012