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Received: July 20, 2011 / Accepted: August 18, 2011 / Published: April 25, 2012.
Abstract: The purposes of the work are elaboration of theoretical statements and technology for steel’s reduction melting that is based on the usage of solid carbon, because at present time it is lack of theoretical and experimental data to make correct decisions, consider new technical requirements and raw material condition. So there are many reserves to conduct deeper and accurate investigations. Research methodology is worked out and is used for sequential-phase interaction between solid carbon and metal oxides. Replacement of hot reduction gases by solid carbon allow to reduce of specific gas outlet for mass unit of metal till 6-8 times, reduce of large metallurgical divisions for charge mixture preparation, implement of high-technology of steel’s reduction melting with capability for direct alloying. Technological scheme of production chain is proposed. The samples of alloyed steel by manganese and chromium are obtained. dissociation mechanism there were proposed thermodynamic data about low dissociation tension of the most of metal oxides including iron oxides. Dispute increased during discussion of metal’s direct reduction by solid carbon. Adsorption-autocatalytic mechanism has been advanced under supervision of academician Chufarov [2], on the base is put reaction of gas-phase reagents with metal oxides. According with authors’ opinion decisive value belongs to absorbability of gas molecules on the surface of solid particles. Stated mechanism consists from five links:(1) adsorption of gas molecules on the surface of solid particles; (2) chemical reaction between gas-reducer and metal oxide molecules; (3) detach of oxygen from metal oxide by gas-reducer molecule; (4) formation of three-atom gas, reaction products (СО2 or Н2О); (5) gas desorption, product of the reaction.
Establishment of the technical policy. Formation of such mechanism has been under affect of practical interpretation of obvious natural phenomenon without consideration of dissociation effect that is inherent for
forces between atoms of metal and oxygen does not disappear, forces become weaker. Therefore oxygen atoms cannot evolve spontaneous to the atmosphere. Depending on interacting forces it forms under layers of short and long range ordering, correspondingly chemisorptions and adsorption layers. Reasoning from system condition it can be marked that adsorption of external gas atmosphere cannot occur directly on the surface of oxides’ lattice and only on the surface of adsorbed under layer of oxides’ gases (oxygen). As shown in the Fig. 2, it can be at equilibrium with adsorbed under layer of oxides’ oxygen. Only exterior heat input can expand thermal dissociation of metal’s oxide, which means weaken the bonds of oxygen adatoms with center and only then new compound can be formed with molecules of gas atmosphere. So it means that admolecules of HRG did not tear but bond of oxygen from dissociated under layers of oxide particles.
The followers of AACM ignored of solid carbon usage as reduction reagent because it is considered only as for interaction in contact-diffusion condition. According with DAM during heating of the system like metal’s oxides and solid carbon parallel goes metal oxide dissociation on the surface of solid particles and electron emission on the surface of
Fig. 2 Scheme of interaction of adsorpted molecules of HRG with surface dissociated and adsorpted layer of oxygen of metals oxides.
1: equilibrium lattice; 2: strained surface crystal lattice; 3: chemisorpted under layer of oxygen of oxides; 4: adsorpted under layer of oxide’s oxygen; 5: adsorpted layer of HRG molecules; q: flow of heat energy.
of metal ingot with chemistry that is presented in the Table 4.
As shown in the Table 4, correct proportion of stoichiomestry quantity of solid carbon for the reduction of different metal oxides in the charge and work-out of reduction-melting conditions allow obtaining of natural-alloyed steel.
Taking into account dissociation-adsorption mechanism of metal’s direct reduction the method for charge mixture combination and preparation has been worked out for implementation of steel’s reduction melting. Mechanism allowed on the basis of balance of gasified oxygen in the charge mixture and
The authors are thankful for funding and supporting
to our government of Kazakhstan and administration
of Kazakh national technical university named after
K.I. Satbayev.
References
[1] А.А. Bayikov, Metals’ reduction and oxidation, Metallurgist, 1926, pp. 5-24.
[2] G.I. Chufarov, Y.А. Tatiyevskaiya, Adsorption-catalytic theory of metal’s oxides reduction, Challenges of metallurgy, Moscow, Academy of science of USSR, 1953, pp. 15-32.
[3] G.I. Chufarov, Y.А. Tatiyevskaiya, Mechanism and kinetics of metals’ reduction, Physics-chemistry fundamentals of blast furnace process and modern practice of hot iron production, Sverdlovsk, 1956, pp. 21-64.
[4] P.V. Geld, Role of gas phase in the reduction of oxides by solid carbon and technology of rare elements, Sverdlovsk, 1957, pp. 8-14.
[5] S.M. Tleugabulov, Dissociation-adsorption mechanism and kinetics of iron’s solid phase reduction by carbon, Steel, Moscow, 1991, pp. 15-18.
[6] S.M. Tleugabulov, Y.Y. Kiyekbayev, G.М. Koishyna, Y.М. Aldangarov, Metals’ direct reduction, high-technology production, Steel, Moscow, 2010, No. 2, pp. 4-8.
[7] S.M. Tleugabulov, High-technology reduction-melting process for steelmaking, Steel, Moscow, 2011, No. 4, pp. 14-19.
[8] D.I. Ryzhonkov, V.D. Tomlyanovich, Mechanism and kinetics of reduction processes, Moscow, MISA, 1986, p. 122.
[9] H.W. Gudenau, From ore till steel, Aachen, RWTU, 1989, p. 495.
[10] O. Sawada, T. Miyamoto, Overview of market for direct reduced iron, Kobelco Technology Review 29 (2010) 47-49.
[11] H. Michishita, H. Tanaka, Prospects for coal-based direct reduced iron, Kobelco Technology Review 29 (2010) 69-76.
[12] V.G. Voskoboinikov, V.A. Kudrin, A.M. Yakushev, Common metallurgy, Moscow, Academy Book, 2002, p. 768.
Abstract: The purposes of the work are elaboration of theoretical statements and technology for steel’s reduction melting that is based on the usage of solid carbon, because at present time it is lack of theoretical and experimental data to make correct decisions, consider new technical requirements and raw material condition. So there are many reserves to conduct deeper and accurate investigations. Research methodology is worked out and is used for sequential-phase interaction between solid carbon and metal oxides. Replacement of hot reduction gases by solid carbon allow to reduce of specific gas outlet for mass unit of metal till 6-8 times, reduce of large metallurgical divisions for charge mixture preparation, implement of high-technology of steel’s reduction melting with capability for direct alloying. Technological scheme of production chain is proposed. The samples of alloyed steel by manganese and chromium are obtained. dissociation mechanism there were proposed thermodynamic data about low dissociation tension of the most of metal oxides including iron oxides. Dispute increased during discussion of metal’s direct reduction by solid carbon. Adsorption-autocatalytic mechanism has been advanced under supervision of academician Chufarov [2], on the base is put reaction of gas-phase reagents with metal oxides. According with authors’ opinion decisive value belongs to absorbability of gas molecules on the surface of solid particles. Stated mechanism consists from five links:(1) adsorption of gas molecules on the surface of solid particles; (2) chemical reaction between gas-reducer and metal oxide molecules; (3) detach of oxygen from metal oxide by gas-reducer molecule; (4) formation of three-atom gas, reaction products (СО2 or Н2О); (5) gas desorption, product of the reaction.
Establishment of the technical policy. Formation of such mechanism has been under affect of practical interpretation of obvious natural phenomenon without consideration of dissociation effect that is inherent for
forces between atoms of metal and oxygen does not disappear, forces become weaker. Therefore oxygen atoms cannot evolve spontaneous to the atmosphere. Depending on interacting forces it forms under layers of short and long range ordering, correspondingly chemisorptions and adsorption layers. Reasoning from system condition it can be marked that adsorption of external gas atmosphere cannot occur directly on the surface of oxides’ lattice and only on the surface of adsorbed under layer of oxides’ gases (oxygen). As shown in the Fig. 2, it can be at equilibrium with adsorbed under layer of oxides’ oxygen. Only exterior heat input can expand thermal dissociation of metal’s oxide, which means weaken the bonds of oxygen adatoms with center and only then new compound can be formed with molecules of gas atmosphere. So it means that admolecules of HRG did not tear but bond of oxygen from dissociated under layers of oxide particles.
The followers of AACM ignored of solid carbon usage as reduction reagent because it is considered only as for interaction in contact-diffusion condition. According with DAM during heating of the system like metal’s oxides and solid carbon parallel goes metal oxide dissociation on the surface of solid particles and electron emission on the surface of
Fig. 2 Scheme of interaction of adsorpted molecules of HRG with surface dissociated and adsorpted layer of oxygen of metals oxides.
1: equilibrium lattice; 2: strained surface crystal lattice; 3: chemisorpted under layer of oxygen of oxides; 4: adsorpted under layer of oxide’s oxygen; 5: adsorpted layer of HRG molecules; q: flow of heat energy.
of metal ingot with chemistry that is presented in the Table 4.
As shown in the Table 4, correct proportion of stoichiomestry quantity of solid carbon for the reduction of different metal oxides in the charge and work-out of reduction-melting conditions allow obtaining of natural-alloyed steel.
Taking into account dissociation-adsorption mechanism of metal’s direct reduction the method for charge mixture combination and preparation has been worked out for implementation of steel’s reduction melting. Mechanism allowed on the basis of balance of gasified oxygen in the charge mixture and
The authors are thankful for funding and supporting
to our government of Kazakhstan and administration
of Kazakh national technical university named after
K.I. Satbayev.
References
[1] А.А. Bayikov, Metals’ reduction and oxidation, Metallurgist, 1926, pp. 5-24.
[2] G.I. Chufarov, Y.А. Tatiyevskaiya, Adsorption-catalytic theory of metal’s oxides reduction, Challenges of metallurgy, Moscow, Academy of science of USSR, 1953, pp. 15-32.
[3] G.I. Chufarov, Y.А. Tatiyevskaiya, Mechanism and kinetics of metals’ reduction, Physics-chemistry fundamentals of blast furnace process and modern practice of hot iron production, Sverdlovsk, 1956, pp. 21-64.
[4] P.V. Geld, Role of gas phase in the reduction of oxides by solid carbon and technology of rare elements, Sverdlovsk, 1957, pp. 8-14.
[5] S.M. Tleugabulov, Dissociation-adsorption mechanism and kinetics of iron’s solid phase reduction by carbon, Steel, Moscow, 1991, pp. 15-18.
[6] S.M. Tleugabulov, Y.Y. Kiyekbayev, G.М. Koishyna, Y.М. Aldangarov, Metals’ direct reduction, high-technology production, Steel, Moscow, 2010, No. 2, pp. 4-8.
[7] S.M. Tleugabulov, High-technology reduction-melting process for steelmaking, Steel, Moscow, 2011, No. 4, pp. 14-19.
[8] D.I. Ryzhonkov, V.D. Tomlyanovich, Mechanism and kinetics of reduction processes, Moscow, MISA, 1986, p. 122.
[9] H.W. Gudenau, From ore till steel, Aachen, RWTU, 1989, p. 495.
[10] O. Sawada, T. Miyamoto, Overview of market for direct reduced iron, Kobelco Technology Review 29 (2010) 47-49.
[11] H. Michishita, H. Tanaka, Prospects for coal-based direct reduced iron, Kobelco Technology Review 29 (2010) 69-76.
[12] V.G. Voskoboinikov, V.A. Kudrin, A.M. Yakushev, Common metallurgy, Moscow, Academy Book, 2002, p. 768.