Surface Tension of Melts of CaO–SiO2–Al2O3–B2O3 System
Akberdin A.A. Kim A.S. Sultangaziev R.B.
January 2021Pleiades journals
Steel in Translation
2021#51Issue 115 - 21 pp.
Abstract: 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 melt composition has been created and diagrams in the form of tetrahedron sections in B2O3 have been constructed. In the CaO–SiO2–Al2O3 system, which is the basis for metallurgy, melts with a high surface tension adjoin the binary side of CaO–Al2O3 in the calcium aluminate crystallization area which have small sizes, high charge and, thus, 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 Si2O76-, and ring complex [Si3O9]6– pseudo-wollastonite anion. The anion complication 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 (BO45-) to three oxygen-coordinated state (BO33-). Formed flat triangles BO33- or complexes with them are loosely related to the melt’s volume, 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 capillary activity closeness 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 lying drop method. 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 metal loss 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.
anions , boron , charge , diagram , mathematical model , surface tension
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Abishev Chemical-Metallurgical Institute, Karaganda, 100009, Kazakhstan
Abishev Chemical-Metallurgical Institute
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