Search Documents

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By Nathalie Neveux

For the first time, dehydrated ferrous sulfate was successfully used for the dry synthesis of potassium ferrate. In addition, ferrate ion is stabilized as a solid solution where hexavalent iron is partially substituted by S(V1) leading to a sulfato-ferrate having the following formula K2(Fe,S)04. This substance has an efficient life time of about six months. Ferrate ion is a powerful oxidant ( EO = 2.2V ), a bactericidal agent and possesses coagulant, flocculant properties. Its reduction generates nascent oxygen, hydroxyl groups and Fe(OH)3. Alkali metal ferrate is probably the future global agent for water treatment. Applications of this material in the field of urban and industrial effluents treatment have been investigated. Heavy metals cations such as Cu, Cd, Mn, Ni, Pb, Zn, ... were successfully removed. The results of sulfato-ferrate use for cyanide destruction, decrease in COD, soil, discoloration of pulp and paper effluents will be summarized.

Jan 1, 1999

By K. M. Parida

The kinetics of dissolution of manganese dioxide in dilute sulphuric acid solution have been investigated using iron pyrites as a reductant. The dissolution rate of manganese is independent of the speed stirring but depends upon temperature, particle size, specific surface area of manganese ore, acid concentration, Fe(II) concentration and amount of pyrite. The activation energy is 43.6 KJ/mol and the linear relationship between the rate of dissolution and lido indicates that the reaction is chemically-controlled. The redox reactions of MnO2 with iron pyrites and Fe(II) are the rate-controlling reactions.

Jan 1, 1990

By Zhongning Shi, Ramana G. Reddy, Min Li, Zhaowen Wang

Electrodeposition of cobalt from cobalt tetrafluoroborate (Co(BF4)2) was investigated using 1- butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) ionic liquid. The experiments were conducted at 353 K. Chronoamperometry experiments confirm that the electrodeposition of cobalt on tungsten electrode proceeds via three-dimensional instantaneous nucleation with diffusion-controlled growth process. The average diffusion coefficient of Co(II) was found to be 7.5 × 10-8 cm2s-1 at 353 K, which is in good agreement with the estimated value from cyclic voltammetry. The electrochemical deposit was characterized using SEM-EDS and XRD methods. The SEM image shows formation of a dense and compact deposit at - 0.75 V. The EDS and XRD analysis confirm that the obtained deposit is pure cobalt metal.

Jan 1, 2015

By E. J. Peterson

Oil shale retorting induces mineral and chemical reactions to occur on the macroscopic and microscopic levels in the kerogen-bearing marlstone. The nature and extent of the reactions is dependent upon process variables such as maximum temperature, time at temperature, atmosphere, and raw shale composition. This report describes the investigation of the mineral, chemical, and trace element release properties of spent shales retrieved from an experimental in situ retort at Occidental Oil Shale, Inc. 's Logan Wash site in Garfield County, Colorado. Correlation between mineralogy of the spent materials and the mobility of major, minor, and trace elements are indicated, and relationships with important process parameters are discussed. The progress .of carbonate decomposition reactions and silicat ion reactions is indicative of the processing conditions experienced by the shale materials and influences the mobility of major, minor, and trace elements when the solids are contacted by water. Shale minerals that are exposed to the extreme conditions reached in underground retorting form high temperature product phases including akermanite-gehlenite and diopside-augite solid solutions, kalsilite, monticellite, and forsterite. The persistence of relatively thermally stable phases, such as quartz, orthoclase, and albite provide insight into the extremes of processing conditions experienced by the spent shales. Leachate compositions suggest that several trace elements, including vanadium, boron, fluoride, and arsenic are not rendered immobile by the formation of the high-temperature silicate produce phase akermanite-gehlenite.

Jan 1, 1981

By W. R. McDonald

The U.S. Bureau of Mines investigated treatment of gold and silver refractory ores and concentrates that respond poorly to conventional cyanidation techniques due to the complex mineralogy of the ore. Three types of ores were investigated: gold locked placer sands, gold locked in sulfides, and gold that is robbed from the pregnant cyanide solutions by minerals in the ore. Ore treatment included grinding, flotation, cyanidation, air oxidation, pressure oxidation, hypochlorite oxidation, roasting, and carbon in leach.

Jan 1, 1991

By Sabine Knott

The thermodynamic properties of four liquid ternary zinc alloys, Au-Sn-Zn, Ag-Sn-Zn, AI-Sn- Zn and Cu-In-Zn were measured with an electromotive force (emf) method at three or four cross-sections with an constant X:Sn or Cu-In ratio. At the Au-Sn-Zn and AI-Sn-Zn system calorimetric measurements were also carried out in order to compare the integral enthalpy of mixing from the direct measurements with the data of the emf measurements, which were derived by Gibbs-Duhem integration.

Jan 1, 2003

By Duclerc Fernandes Parra, Washington Luiz Oliani, Christiano Gianesi Bastos Andrade, Ademar Benevolo Lugão, Danilo Marin Fermino, Francisco R. Valenzuela Diaz

This work concerns the study of the effect of discarded bond paper on the mechanical behavior of polypropylene/organophilic clay nanocomposites. A brown polycationic bentonite from the state of Paraíba, Brazil, was treated with sodium carbonate to transform it into a bentonite that swells in water and then treated with hexadecyltrimethylammonium ammonium chloride to transform it into a bentonite that swells in organic liquids. Polypropylene with 3 % polypropylene graft compatibilizer (PP-g-AM) was mixed with 1 % and 2 % by weight of discarded bond paper and with 1% and 2% by weight of organophilic clay using a twin-screw extruder. The specimens were prepared by the injection process. The clay as received and after organophilization was characterized by XRD, SEM, and capacity of swelling in water and in organic solvents. The nanocomposite specimens were characterized by XRD and thermal analysis. The mechanical behavior of the injected specimens was evaluated by strength, flexural and impact tests. The nanocomposites showed improved mechanical properties compared with the polymer without filler.

Jan 1, 2015

By Sabine Knoll

The thermodynamic properties of four liquid ternary zinc alloys, Au-Sn-Zn, Ag-Sn-Zn, AI-Sn Zn and Cu-In-Zn were measured with an electromotive force (emf) method at three or four cross-sections with an constant X:Sn or Cu-In ratio. At the Au-Sn-Zn and AI-Sn-Zn system calorimetric measurements were also carried out in order to compare the integral enthalpy of mixing from the direct measurements with the data of the emf measurements, which were derived by Gibbs-Duhem integration.

Jan 1, 2003

By S. G. Galbraith

We have used the principles of supramolecular chemistry to develop reagents to transport metal salts. These reagents have separated charged "compartments" which recognize a metal cation and its attendant anion(s). They are easy to manufacture as they are structurally related to the commercial hydroxy-oxime extractants for copper. Efficient protocols for loading and stripping of these extractants depend on the novel feature that they bind the metal salt in a zwitterionic form of the ligand. Transfer of the phenolic protons to the pendant amines generates the charged "compartments" to accommodate the metal cation and its attendant anion(s). This paper focuses on how these types of reagent can be used to recover base metals from sulfate and chloride media in flowsheets in which solvent extraction effects separation and concentration operations, interfacing between conventional leach and electrowin/reduction processes. Work on the development of reagents that have high selectivity for metal chloride/sulfate transport, convenient stripping protocols and appropriate hydrolytic stability will be described.

Jan 1, 2003

By Uchil Jayagopal, P. V. Krupakara, S. Manjunath

"This paper deals with the corrosion characterization of quartz particlate ZA-27 alloy metal matrix composites (MMCs). Quartz particles of size 50-80 microns are used as reinforcement. MMC's are prepared according to ASTM standards. Composites containing. 2, 4, and -6% by weight of quartz and unreinforced matrix were tested using 1 -N hydrochloric acid: The composite was found to be more corrosive resistant than matrix alloy. In each test the corrosion resistance of both alloy and composites were found to decrease with the exposure time.1. IntroductionMetal matrix composites- (MMCs) offer designers many added benefits, as they are particularly suited for applications requiring good strength at high temperature, good structural rigidity, dimensional stability, and light weight 1-5. The trend is towards safe usage of the MMC parts in the automobile engine, which work particularly at high temperature and pressure environments Particles reinforced MMCs has been the most popular over the last two decades.ZA alloy MMCs have most popular families being represented by. ZA-27 alloy reinforced with ceramic particulate. Although the incorporation of the second phase into a matrix material can enhance the physical and mechanical properties of the base metal, it could also significantly change the corrosion behavior.ZA alloys have been used extensively in industry. This is attributed to their excellent fludity, castability and good mechanical properties. Among the zinc-based foundry alloys, the ZA family of alloy have been widely used during the past few years. ZA alloys have many advantage over aluminium based ones, especially high strength with a low casting temperature 8."

Jan 1, 2000

By G. Kyle Green

Zirconium chlorinator residues contain an array of rare earths, scandium, unreacted coke, and radioactive thorium and radium. Because of the radioactivity, the residues must be disposed in special waste containment facilities. As these sites become more congested, and with stricter environmental regulations, disposal of large volumes of wastes may become more difficult. To reduce the mass of disposed material, the U.S. Bureau of Mines (USBM) developed technology to recover rare earths, thorium and radium, and unreacted coke from these residues. This technology employs an HCl leach to solubilize over 99% of the scandium and thorium, and over 90% of the rare earths. The leach liquor is processed through several solvent extraction stages to selectively recover scandium, thorium, and rare earths. The leach residue is further leached with an organic acid to solubilize radium, thus allowing unreacted coke to be recycled to the chlorinator. The thorium and radium waste products, which comprise only 2.1% of the original residue mass, can then be sent to the radioactive waste facility.

Jan 1, 1995

By A. D. Damodaran

Batch scale and continuous rotary kiln carbothermic metallisation of ilmenite followed by different down-stream treatments such as catalytic rusting, acidic chloride leaching, oxidation-leaching etc. has given rise to a high grade synthetic rutile (98% TiO2). Rotary reactor metallisation experiments had concurrently given important information with respect to mean residence time, dispersion number, hold-up and axial velocity profiles of the solids bed. A mathematical model based on law of additive reaction times has indicated that Boudouard reaction becomes faster than reduction reaction at higher conversions. A possible use of high grade synthetic rutile in paint industry and metallised ilmenite as welding electrode flux material are discussed.

Jan 1, 1992

By Xuerong Wen

The oxidation behavior of TiAl3 intermetallics was investigated as a hnction of time at 1273K in pure dry oxygen. The oxidation experiments were carried out using TGA method. The oxidation scales were analyzed using SEM, EDS and X-ray diffraction methods. The structures of oxides formed at the different oxidation times were analyzed. The mechanism of oxidation of TiAl3 intermetallics was discussed.

Jan 1, 1998

By May Nyman

Due to the vast diversity of chemical media in which metal separations are executed, a wide range of ion separation materials are employed, This ,results in an ongoing effort to discover new phases with novel ion exchange properties. We present here the synthesis of a novel class at, thermally and chemically stable microporous, niobate-based materials. Ion exchange studies show these new phases are highly selective for Sr2+ and other bivalent metals.

Jan 1, 1999

By S. R. Reddy

Thennodynamic properties of several quaternary systems are calculated using our recently modified Margules equations. The modified Margules equations are expressed up to infinite order in the vicinity of solvent. Quaternary system of one solvent and three,solute partials are derived. First order interaction coefficients of binary, ternary and cross -interaction parameters of quaternary system are used to'evaluate the partial functions. In the original fonn of Margules equations,derived partial functions are convergent and same 'as Unified ,Interaction Parameter Fonnalism. But considering up to infinite order of the Margules coefficients, the functions are divergent, in order to overcome this restriction, Margules equations are modified to get consistent equations. Derived partial functions are thennodynamica Hy consistent with Maxwell and Gibbs Duhem relations. The derived logarithmic activity coefficient of the solvent and solutes are consistent with the ternary systems. The calculated data, ie., activity coefficient values of nitrogen and interaction coefficients are in good agreement with the data of Fe-Cr-V -N. Fe-Ni-V -N, Fe-Cr-Ta-N and Fe-Ni-Ta-N systems.

Jan 1, 1999

By Liyuan Chai

The corrosion mechanism of A3 steel induced by chloride ions in the purified water had been investigated with the A C Impedance technique. The results showed that there were another two factors which determined its electrochemical corrosive rate: the electrode potential and coverage ratio of chloride ions on the surface of A3 Steel. The corrosion mechanism of A3 steel in the solution with chloride ions emendation was two steps of electrode process with the rate-determining step of 0,32kFeClFeCle+--¾¾®++.

Jan 1, 2009