Surface tension of melts of СаО – SiO₂ – Al₂O₃ – В₂O₃ system

Using the method of experiment planning by simplex, the surface tension of the melts of СаО – SiO₂ – Al₂O₃ – В₂O₃ system was researched. The local part of the system was explored which covered the process of ferrosilicon, silicochrome, cement clinker, ceramics, glass, and sittals production. The amount of oxides in it was (%): 9.8 – 52.0 CaO; 0 – 70.4 SiO₂; 0 – 51.5 Al₂O₃ and 0 – 20 B₂O₃. A mathematical model of surface tension dependence on the melts composition has been created and diagrams in the form of tetrahedron sections in B₂O₃ have been constructed. It was found that, in the CaO – SiO₂ – Al₂O₃ system, which is basic for metallurgy, melts with a high surface tension adjoin the binary side of CaO – Al₂O₃ in the area of calcium aluminates crystallization which have small sizes, high charge and due to this bond to melt volume. With the introduction of SiO₂ , σ of melts decreases due to the formation of large aluminosilicon formations of the [Al₂Si₂O₈]^2– type, rankinite groups Si₂O₇^6-, and ring complex [Si₃O₉]^6- pseudo-wollastonite anion. The complication of anions due to polymerization leads to a drop of surface tension because of a decrease in charge ratio of the latter to the radius and, consequently, the strength of bond with cations. Boron anhydride injection causes a decrease in surface tension of melts СаО – SiO₂ – Al₂О₃ which can be explained by boron transition at high temperature from four oxygen-coordinated (BO₄^5-) to three oxygen-coordinated state (BO₃^3-). Formed flat triangles BO₃^3- or complexes with them are loosely related to the melt’s volume, they are forced out to the surface and reduce surface tension. Mostly this affects the main aluminate melts, rather than acid ones. The latter can be explained by the closeness of the capillary activity of boron – and silicon-oxygen anions. The surface phenomena between the products of blast-furnace smelting of titanomagnetite iron ores have been studied experimentally using the method of lying drop. It was noted that the highest adhesion forces (work of adhesion) take place between slag and grenal (cast iron with a high titanium and silicon content), which is the reason for the loss of metal at the outlet with slags during the processing of such ores. Boron loaded into the blast furnace (in the form of natural ores) is redistributed under reduction conditions between cast iron, grenal and slag. Experiments have shown that the presence of boron in slag at the level of microconcentrations reduces the work of adhesion from 688 to 436 MN/m (by 37 %). Industrial experiments have shown that this helped to reduce the loss of valuable vanadium-containing cast iron with slags by 1.2 – 1.5 times with a simultaneous improvement in smelting performance.

boron, anions, charge, surface tension, mathematical model, diagram

1. Popel’ S.I. Surface Phenomena in Melts. Moscow: Metallurgiya, 1994, 440 p. (In Russ.).

2. Arutyunyan N.A., Zaitsev A.I., Shaposhnikov N.G. Surface tension of CaO–Al O 3 , CaO–SiO 2 , and CaO–Al 2 O3 –SiO melts. Russian Journal of2 Physical Chemistry A. 2010, vol. 84,2 no. 1, pp. 7–12. https://doi.org/10.1134/S0036024410010024.

3. Picha R.,Vrestal J., Kroupa A. Prediction of alloy surface tension using a thermodynamic database. CALPHAD – Computer Coupling of Phase Diagrams and Thermochemistry. 2004, vol. 28, no. 2, pp. 141–146. https://doi.org/10.1016/j.calphad.2004.06.002

4. Bulter A.V. The thermodynamics of the surfaces of solutions. Proceedings of the Royal Society A: Mathematical, Physical & Engineering Sciences. 1932, vol. 135, pp. 348–375.

5. Yeum K.S., Speiser R., Poirier D.R. Estimation of the surface tensions of binary liquid alloys. Metallurgical Transactions B. 1989, vol. 20, no. 5, pp. 693–703. https://doi.org/10.1007/BF02655927

6. Tanaka T., Lida I. Application of a thermodynamic database to the calculation of surface tension for iron-base liquid alloys. Steel Research. 1994, vol. 6, no. 1, pp. 21–28. https://doi.org/10.1002/srin.199400921

7. Panfilovich K.B. Surface tension of liquid binary alloys. Vestnik KTU. 2006, no 4, pp. 106–111. (In Russ.).

8. Hultgren R., Desai P.T., Hawkins D.T. Selected Values of the Thermodynamic Properties of Binary Alloys. New York: American Society of Metals, 1973, 1275 p.

9. Panfilovich K.B. Thermal Radiation and Surface Tension of Liquid Metals and Alloys. Kazan: KSTU, 2009, 256 p. (In Russ.).

10. Siegel R., Howell J.R. Thermal Radiation Heat Transfer. New York: McGraw-Hill Book Company, 1972, 934 p.

11. Sprow F.B., Prausnitz J.M. Surface tensions of simple liquid mixtures. Transactions of the Faraday Society. 1966, vol. 62, no. 5, pp. 1105–1111.

12. Nakashima K. Interfacial properties of liquid iron alloys and liquid slags relating to iron and steel-making processes. ISIJ International. 1992, vol. 32, no. 1, pp. 11–18. https://doi.org/10.2355/isijinternational.32.11

13. Makurov S.L. Study of surface tension of slag-forming mixtures for continuous casting mold. Vіsnik Priazovs’kogo derzhavnogo tekhnіchnogo unіversitetu: zb. nauk. prats’. 2007, vol. 17, pp. 46–49. (In Russ.).

14. Tkachev I.V., Plyshevskii Yu.S. Technology of Boron Inorganic Compounds. Leningrad: Khimiya, 1983, 208 p. (In Russ.).

15. Lyakishev I.P., Pliner Yu.L., Lappo S.I. Boron-Containing Steels and Alloys. Moscow: Metallurgiya, 1986, 192 p.

16. Churyumov A.Yu., Khomutov M.G., Tsar’kov A.A., Pozdnyakov A.V., Solonin A.N., Mukhanov E.L. Boron-containing steel structure and properties at room and elevated temperature. Metallurgist. 2015, vol. 58, no. 11-12, pp. 992–997. https://doi.org/10.1007/s11015-015-0029-1

17. Semenchenko V.K. Surface Phenomena in Metals and Alloys. Moscow: Gosudarstvennoe izdatel’stvo tekhniko-teoreticheskoi literatury, 1957, 492 p. (In Russ.).

18. Akberdin A.A., Kim V.A., Nikolai E.I., Kulikov I.S. Planirovanie eksperimenta pri issledovanii fiziko-khimicheskikh svoistv metallurgicheskikh shlakov. Alma-Ata: Nauka,1989, 116 p. (In Russ.).

19. Nazarov B.K., Akberdin A.A. Calculation of the equilibrium phase composition in the B2 O 3 – CaO – SiO 2 – Al2 O 3 system. Russian metallurgy. Metally. 1987, no 4. pp. 221–223.

20. Berezhnoi A.S. Multicomponent Oxide Systems. Kiev: Naukova dumka, 1970, 544 p. (In Russ.).

21. Schlackenatlas. Verein Deutscher Eisenhüttenleute. Verlag Stahleisen, 1981, 282 p. (Russ. ed.: Atlas shlakov. Sprav. Moscow: Metallurgiya, 1985, 208 p.)

22. Manyak N.M., Ogunlana O.A., Dolzhenkova E.F. Surface tension of iron-boron melts. Izvestiya. Ferrous Metallurgy. 1986, no. 8, pp. 147–148. (In Russ.).

23. Novikov V.S., Shavrin S.V., Fofanov A.A. Smelting of vanadium cast iron in large blast furnaces. In: Production of Alloyed Cast Iron and Steel: Scientific Papers of UralNIIIChM. Sverdlovsk, 1982, pp. 5–17. (In Russ.).

24. Akberdin A.A, Kim A.S. Reserves of the blast furnace process for production of high-quality rolled steel. In: Transactions of Int. Sci. and Pract. Conf. “Scientific and Technical Progress in Metallurgy”, September 29-30, 2005, Temirtau. Temirtau: 2005, pp. 148–156. (In Russ.).