The research presents the calculations of the analytical expressions of the oxide system MnO-CaO-Al2O3-SiO2 and the phase compositions of the slags from the production of refined ferromanganese. It is determined that the system under consideration is divided into 19 elementary quasi-systems consisting of incongruently melting and congruently melting compounds. The sum of the relative volumes of the elementary tetrahedron of the MnO-CaOAl2O3-SiO2 system equals one (1,000000), which confirms the accuracy of the performed calculations. Quasi-volumes in the system MnO-CaO-Al2O3-SiO2, simulating the composition of the resulting slag in the process of metallothermic recovery of manganese concentrates are found

A. Abdirashit

A. Baisanov

A. Issagulov

D. Yessengaliyev

O. Zayakin

S. Baisanov

English

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291METALURGIJA 58 (2019) 3-4, 291-294D. YESSENGALIYEV, S. BAISANOV, A. ISSAGULOV, A. BAISANOV, O. ZAYAKIN, A. ABDIRASHITTHERMODYNAMIC DIAGRAM ANALYSIS (TDA) OF MnO–CaO-Аl2O3-SiO2 AND PHASE COMPOSITION OF SLAG IN REFINED FERROMANGANESE PRODUCTIONReceived – Primljeno: 2019-01-12Accepted – Prihvaćeno: 2019-03-28Preliminary Note – Prethodno priopćenjeD. Yessengaliyev, (dauralga@mail.ru) A. Issagulov, Karaganda State Technical University, Karaganda, KazakhstanS. Baisanov, A. Baisanov, Che mical-Metallurgical Institute, Karagan-da, KazakhstanO. Zayakin, Institute of Metallurgy, Yekaterinburg, RussiaA. Abdirashit, Aktobe regional state of university, Aktobe, KazakhstanThe research presents the calculations of the analytical expressions of the oxide system MnO-CaO-Al2O3-SiO2 and the phase compositions of the slags from the production of refined ferromanganese. It is determined that the sys-tem under consideration is divided into 19 elementary quasi-systems consisting of incongruently melting and con-gruently melting compounds. The sum of the relative volumes of the elementary tetrahedron of the MnO-CaO-Al2O3-SiO2 system equals one (1,000000), which confirms the accuracy of the performed calculations. Quasi-volumes in the system MnO-CaO-Al2O3-SiO2, simulating the composition of the resulting slag in the process of metallother-mic recovery of manganese concentrates are found.Key words: thermodynamic-diagram analysis, refined ferromanganese, phase composition, oxide system, metallo-thermyINTRODUCTIONIn metallurgy it’s important to study the state of ma-terials that involve in metallurgical conversion, depend-ing on temperature and pressure. However, the classical thermodynamic study of processes in complex systems is rather lengthy and requires using complex mathemat-ical calculations and it’s associated with the need to de-termine the thermodynamic parameters of a large num-ber of independent reactions. Often data on variety of substances that are necessary to determine changes in Gibbs free energy, are limited or absent, which in such cases exclude the thermodynamic analysis possibility of multicomponent system. Moreover, the latter does not consider the particular intermediate stages of the process, since it only operates with input and output pa-rameters of the process.An alternative variant to the classical thermodynam-ic study of processes in metallurgy is method of analyz-ing geometric thermodynamics – thermodynamic dia-gram analysis (TDA), developed by the Chemical Met-allurgical Institute (CMI).This method is particularly effective in terms of ap-plication to metallurgical technologies, since it allows to reveal the features of the phase state of the raw mate-rials involved in the metallurgical conversion. Howev-ISSN 0543-5846METABK 58(3-4) 291-294 (2019)UDC – UDK 536.777:669.15.74:536.425:541.451:517.9 = 111er, the final result of such researches is a diagram of the phase composition of a single system that is closest to the composition of metallurgical products. Using this diagram, the evolution of phase transformations in slags and metal systems can be visually traced and predict their final state.RESEARCH METHODOLOGYIn this work, an attempt has been made to create a mathematical model for estimating the type and number of forming phases in the slag system of refined ferro-manganese production. It’s well known the technology of refined ferromanganese production characterized in the initial periods of melting by slags of the FeO-MnO-CaO-Al2O3-SiO2 system to the final period – by the same system without iron oxide (II).However the phys-ico – chemical properties of the latter system have cru-cial Impact on value outputs of the technology as a whole. [1]. In order to determine the tetrahedron in the MnO-CaO-Аl2O3-SiO2 system to the refined ferroman-ganese slags, first of all, it is necessary to find those el-ementary tetrahedrons in which they are located. Then, focusing on the location of slags in one or another tetra-hedron, as well as on the normative distribution of their main components between the compounds (secondary phases) located on the tops of this tetrahedron, it is pos-sible to give a qualitative and quantitative technological assessment of the materials under study. Then, focusing on the location of slags in one or another tetrahedron, as well as on the normative distribution of their main com-ponents between the compounds (secondary phases) 292D. YESSENGALIYEV et al.: THERMODYNAMIC DIAGRAM ANALYSIS (TDA) OF MnO–CaO-Al2O3-SiO2 … METALURGIJA 58 (2019) 3-4, 291-294located on the vertex corners of this tetrahedron, it is possible to give a qualitative and quantitative techno-logical assessment of the being studied materials. For this we have organized complete TDA of the MnO-CaO-Аl2O3-SiO2 system.The four-component MnO-CaO-Аl2O3-SiO2 system is assembled from the individual ternary systems MnO-CaO- SiO2, MnO-Аl2O3-SiO2, MnO-CaO-Аl2O3 and CaO-Аl2O3-SiO2. Based on the calculated thermody-namic data, a diagram of the four-component system MnO-CaO-Al2O3-SiO2 was constructed and a mathe-matical model of its phase structure was created [2]. Unknown thermodynamic constants of binary com-pounds are calculated by using the models available in the literature [3–5]. To simplify the comprehension of this diagram and its phase structure, it’s moved apart into integral parts. The transformation coefficients cal-culated by the method of Heath [6] are intended to de-termine the phase composition of the primary compo-nents (by chemical composition). Analysis of the phase equilibrium of the compounds of the MnO-CaO-Al2O3-SiO2 quadruple system, which simulate the phase com-positions of the remaining slags of the silicothermic, aluminothermic, alumino-silicothermic (metallother-my) ferromanganese, leads to the conclusion that we considering that four-component system consists of 19 elemental tetrahedrons, volumes (relative to the volume of the general system equal to 1 in terms of the units) are presented in Table 1. The breakdown of the general system is carried out with congruently melting com-pounds by combining a metastable conod of incongru-ent secondary components into stable triangles. The to-tal of the relative volumes of elementary tetrahedrons is equal to one (1,000000), which confirms the correct-ness of the tetrahedration.In work [6] have been explained the easiest and ac-cessible method for manual calculations the derivation of transformation equations, that expresses any second-ary system through primary systems of basic system. Calculated by the Heath equation the positive quantity of all the n-th amount coefficients of secondary compo-nents of a particular polytope, are the criterion for the location of a given composition of the melt in one of the quasi-systems. From what has been said, coefficients were tabulated in Table 2, which had been calculated by us by the procedure [6] for each secondary component of 19 congruently melting quasi-systems of the basic tetrahedron.RESULTS RESEARCHThe practical using of the TDA results specifically to the slags from the production of refined ferromanga-nese lies in the fact of finding the elementary tetrahe-dron, within which their compositions are located, and the normative distribution of primary phases between secondary compounds for them is equal to 100% of the considered tetrahedron. To determine the technological effectiveness of the generating slags during the smelt-ing process, it is necessary to recalculate average weighted material compositions into four main oxides of the MnO-CaO-Аl2O3-SiO2, system, which are listed in Table 3 [7]. The phase composition in each of the tetrahedrons in Table 1 can be described by substituting the proper coefficients from Table 2 into the equation: Xi = aiCo + biMo + ciAo + diSowhich is the transformation equation (according to Heath), where Xi is the amount of the secondary form-ing phase; ai, bi, ci, di - transformation ratios; Co, Mo, Ao, So - the number of primary oxide components in the melt.Using silicomanganese as reducing agent in produc-tion of refined ferromanganese in the analysis of slag compositions it was established that:• Slag composition of low carbon ferromanganese (14,0% MnO; 46,0% CaO; 31,0% SiO2; 2,15% Al2O3) simulated by tetrahedron 2CaO∙Al2O3∙SiO2-CaO∙SiO2 - 2MnO∙SiO2 - 2CaO∙SiO2 (relative volume V = 0.043935), for which transformation equations to calculate the equilibrium ratios of the secondary components through primary component are written in the form of system of four linear expressions:C2AS = 2,68817∙A;CS = -1,63709∙M-2,07738∙C+ 3,87500∙S+0,00275∙A;M2S = 1,42248∙M;C2S = 1,21462∙M+ 3,07738∙C-2,87500∙∙S-1,69092∙A.Table 1  The list of elementary tetrahedrons MnO-CaO-Al2O3-SiO2 No. Tetrahedrons Elementary volumes1 C-C12A7-C2S-M 0,1797352 C12A7-AC-C2S-M 0,0457193 AC-C2AS-C2S-M 0,0458484 AC-A2C-C2AS-M 0,0304415 M-MA-A2C-C2AS 0,0277806 MA-A2C-A-C2AS 0,0193057 A-C2AS-CAS2-MA 0,0543948 A-A3S2-CAS2-MA 0,0232409 A3S2-MA-M3AS3-CAS2 0,03113110 S-A3S2-CAS2-M3AS3 0,06205711 MA-M3AS3-CAS2-M 0,04316712 C2AS-CAS2-MA-M 0,07827513 S-M3AS3-M2S-CAS2 0,02910814 M2S-M3AS3-M-CAS2 0,01229815 M-M2S-CAS2-C2AS 0,02237316 CS-CAS2-C2AS-M2S 0,05465517 CS-C2S-M2S-C2AS 0,04393518 C2S-C2AS-M-M2S 0,07192519 S-CS-M2S-CAS2 0,124614Total 1,000000293D. YESSENGALIYEV et al.: THERMODYNAMIC DIAGRAM ANALYSIS (TDA) OF MnO–CaO-Al2O3-SiO2 …METALURGIJA 58 (2019) 3-4, 291-294Table 2  The list of elementary tetrahedrons, their volumes and the coefficients of the equations to calculate the equilibrium ratios of the secondary components of the MnO-CaO-Аl2O3-SiO2 systemcomponentscoeffi  cientsQuasi-quad systems, their volumes and transformation coeffi  cients1 2 3 4 5 6 7 8 9 10C2S- C2S- C2AS- A2C- M- A- A- A- CAS2- S-C- AC- M- AC- C2AS- C2AS- C2AS- A3S2- A3S2- A3S2-C12A7- C12A7- AC- C2AS- A2C- A2C - CAS2- CAS2- M3AS3- CAS2-M M C2S M MA MA MA MA MA M3AS3Volumes 0,179735 0,045719 0,045848 0,030441 0,02778 0,019305 0,054394 0,02324 0,03113 0,062057Аl2O3 a1 0 0 2,69469 2,54676 -0,69492 1 1 1 0 -0,39276a2 -0,94175 3,70229 0 -1,54676 0 0 0 0 0,96358 1,39276a3 1,94175 -2,70229 -0,00375 0 0 0 0 0 -0,74651 0a4 0 0 -1,69094 0 1,69492 0 0 0 0,78293 0MnO b1 0 0 0 0 1 -1,43902 -1,43902 -1,43902 0 -0,65835b2 0 0 1 0 0 0 0 0 -1,3866 -0,66723b3 0 0 0 0 0 0 0 0 1,07425 0b4 1 1 0 1 0 2,43902 2,43902 2,43902 1,31237 2,32558SiO2 c1 2,86533 2,86533 9,17262 4,35354 -3,55811 5,12021 -0,56781 -2,5461 0 1c2 -1,86533 7,33316 0 -7,91975 4,56621 4,56621 -1,51505 3,5461 1,09271 0c3 0 -9,19849 -5,28207 4,56621 -8,68642 -8,68642 3,08286 0 1,9007 0c4 0 0 -2,89055 0 8,67832 0 0 0 -1,99341 0CaO d1 0 0 -4,91742 -4,64748 2,53725 -3,65116 -0,6055 3,64634 4,97512 -1,43213d2 1 -3,9313 0 5,64748 0 0 3,25622 -7,62147 -4,10791 -2,543d3 0 4,9313 2,8317 0 4,65116 4,65116 -1,65072 4,97513 -2,72204 4,97513d4 0 0 3,08572 0 -6,18841 0 0 0 2,85483 011 12 13 14 15 16 17 18 19Volumes 0,043167 0,078275 0,029108 0,012298 0,022373 0,054655 0,043935 0,071925 0,12461Аl2O3 a1 -0,69492 -0,69492 -0,88512 2,09509 4,16864 1,34719 2,68817 2,68817 -0,59087a2 0 1,69492 4,85437 -5,94946 -5,92979 -1,70644 0,00275 -0,00168 -1,1339a3 0 0 -2,96924 4,85437 5,42937 0 0 0,00239 0a4 1,69492 0 0 0 -2,66822 1,35925 -1,69092 -1,68888 2,72479MnO b1 1 1 -0,42248 1 1 0,96324 0 0 -0,42248b2 0 0 0 0 0 -0,40935 -1,63709 1 0b3 0 0 1,42247 0 0 1,42248 1,42248 0 1,42248b4 0 0 0 0 0 -0,97637 1,21461 0 0SiO2 c1 -0,78804 0,39458 1 -2,367 -2,367 -2,28 0 0 1c2 -0,95921 -0,96239 0 3,367 3,367 0,96894 3,875 -2,367 0c3 2,74725 3,08286 0 0 0 0 0 3,367 0c4 0 -1,51505 0 0 0 2,31106 -2,875 0 0CaO d1 2,96253 0,42077 -0,53313 1,26192 -2,5241 2,4405 0 0 -1,07039d2 -1,03311 -1,02627 -8,86345 3,6264 3,59048 1,03325 -2,07738 1,26895 2,07039d3 -5,90454 -1,65072 5,42146 -8,86345 -4,93821 0 0 -1,80504 0d4 4,97512 3,25622 4,97512 4,97513 4,87183 -2,47375 3,07738 1,53609 0*Note. The following abbreviations are used in the table: M-MnO; C-CaO; A-Al2O3; S-SiO2This implies that, a slag in the subsolidus state in-cludes itself, % 6,20 C2AS; 1,71 CS; 21,34 M2S; 70,64 C2S.• Composition of highly basic ore-lime melt (12% MnO; 48% CaO; 25,2% SiO2; 2,5% Al2O3) simulated in tetrahedron 2CaO∙Al2O3∙SiO2-MnO-Al2O3∙CaO-2CaO∙SiO2 (relative volume V=0,04585),the given tet-rahedron is characterized by a high content of calcium oxide and ratio of CaO/SiO2 = 1,8-2,2.Analytical expressions of secondary phases are writ-ten as:C2AS=-4,91742∙C+9,17262∙S+2,69469∙A;M = 1,00000∙M;AC = 2,83170∙C-5,28206∙S-0,00375∙A;C2S = 3,08572∙C-2,89055∙S-1,69094∙A.Producing melt will include, %: 27,45 C2AS; 12,00 M; 2,80 АС; 71,05 C2S.The slags from the production of refined ferroman-ganese are reduced by the aluminosilicothermy method that have the following property. Slag compositon шлака (13,0% MnO; 45,6% CaO; 26,0% SiO2; 10,0% Al2O3) simulated in tetrahedron 2CaO∙Al2O3∙SiO2–MnO-2MnO∙SiO2-2CaO∙SiO2 with large relative vol-ume V=0,071925. The transformation equations for the abovementioned quasi-system are written as:C2S= 1,53610∙C-1,68888∙AC2AS= 2,68817∙AM=1,00000∙M+1,26895∙C-2,36700∙S--0,00168∙AM2S=-1,80504∙C+ 3.36700∙S+ 0,00239∙A294D. YESSENGALIYEV et al.: THERMODYNAMIC DIAGRAM ANALYSIS (TDA) OF MnO–CaO-Al2O3-SiO2 … METALURGIJA 58 (2019) 3-4, 291-294Table 3  The weighted average chemical composition of slags from the production of refined ferromanganese smelted by the methods: silicothermy, metallothermy and tetrahedron where they are locatedMaterial MnO CaO SiO2 Al2O3 TetrahedronSilicothermy processSlag refi ned ferromanganese 14,0 46,0 31,0 2,15 C2AS-CS-M2S-C2SOre-lime melt 12,0 48,0 25,2 2,50 С2AS-M-AC-C2SMetallothermy processSlag refi ned ferromanganese13,0 45,6 26,0 10,0 С2AS-M-M2S-C2SThe regulatory phase composition of this slag in-cludes, %: 44,65 C2S; 38,65 C2AS; 11,2 М; 5,5 M2S.It has been established that the slag composition of the refined ferromanganese reduced by the metallother-my method, alumina secondary compounds based on calcium dominate in slag 2CaO∙SiO2∙Al2O3 (to 45 %, instead 6,0 %), which explains the significant decrease in the concentration of 2CaO∙SiO2 (two-calcium sili-cate) (from 75 % to 45 %), which diffuses into powder when cooled. The displacement the remaining slag composition to the side of gehlenite by loading an alu-minum-silicon-manganese-containing alloy as a reduc-ing agent into furnace-charge does not negatively affect on technology of refined ferromanganese smelting. In-cluding the fact that this displacement raises the melting point of the slag and therefore the whole process, con-tributes the complete reduction of manganese and sili-con from their silicates, notably from tephroite (2MnO ∙ SiO2) [8]. However, due to the limited content of silicon in the ferromanganese according to GOST 4755-91, an excessively high content of alumina in the slag is unde-sirable, since this contributes to a deeper recovery of silicon.CONCLUSIONSFrom the above mentioned theoretical data follows validaton of the fact that the TDA, in which neglecting the complex mathematical apparatus, allows using the phase diagrams of multicomponent systems to establish the optimal range of slag compositions. Furthermore, according to the data on the melting points of the sec-ondary components of the elementary volume, it is pos-sible to determine the relative melting points of the re-searched slag.REFERENCES[1] Gabdullin T.G., Takenov T.D., Baisanov S.O., Buketov E.A. Physical-chemical properties of manganese slag – Alma-Ata: Nauka, 1984. 232 p.[2] Baisanov S.O. Regularities of phase equilibria in metallur-gical systems and development of effective technologies for the smelting of ferroalloys on their basis: Dr. Tech. Sci. Diss. - Karaganda: KhMI, 2002. 295p.[3] Kasenov B.K., Aldabergenov M.K., Pashinkin A.S. etc. Method of applied thermodynamics in chemistry and me-tallurgy– Karaganda: Glasir, 2008. – 332 p.[4] Moiseev G.K., Vatolin N.A., Trusov B.G. Thermodynamic modeling in high-temperature inorganic systems – Mo-scow: Metallurgiya, 1994, 353 p.[5] Morachevskii A.G., Sladkov I.B. Guide to thermodynamic calculations – Leningrad: LPI im. M.I. Kalinina, 1975, 66 p.[6] Heath D.L. Mathematical Treatment of Multicomponent Systems. Jour. Amer. Ceram. Soc. – 40(1957) 2, 50-53[7] Zhuchkov V.I., Smirnov L.A., Zaiko V.P., Voronov Yu.I. Technology of manganese ferroalloys part.2. Low carbon alloys. Yekaterinburg: UroRAN, 2008, 435 p.[8] Baisanov S.O., Baisanov A.S., Issagulov A.Z., Yessenga-liyev D.A., Ospanov N.I. Design of technology for refined ferromanganese smelting by using special complex redu-cing agents / Proceedings of higher educational institu-tions. Ferrous metallurgy. 61(2018) 9, 689-694Note:  The responsible for England language is Aigerim Baibulova, Aktobe Kazakhstan

Thermodynamic diagram analysis (TDA) of MnO–CaO-Аl2O3-SiO2 and phase composition of slag in refined ferromanganese production

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Thermodynamic diagram analysis (TDA) of MnO–CaO-Аl2O3-SiO2 and phase composition of slag in refined ferromanganese production

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