Chemical transformations at carbothermal reduction of barium and boron from oxides

Abstract

Alloys of boron and barium are applied to improve the quality of cast iron, steel, aluminum and other metals. The first industry produces mainly in the form of ferroboron, containing 6 – 17 % of boron depending on the brand. It is produced by an expensive aluminothermic method due to the use of boric anhydride and aluminum powder. At the same time, presence of aluminum in the metal is inevitable, it degrades the technological properties of cast iron and forms line alumina inclusions in steel. Extra-furnace removal of Al leads to oxidation of boron and its loss with slags. Therefore, the authors have proposed new methods for smelting boron-containing ferroalloys. Recent developments include the production technology of boron-containing ferrosilicon, which has been tested in industrial conditions. But its use may be limited in smelting of low-silicon steel grades. Barium is an effective modifier. Due to its low solubility in iron, it is produced in the form of alloys with silicon or aluminum. In the first case, silicides (BaSi, BaSi2 ) are formed and therefore such alloys are called silicon barium or ferrosilicon with barium. In present work, there has been studied the possibility of producing modifier with boron and barium ferroalloy. It was believed that the simultaneous presence of barium and boron in it can be demand for industry. At the first stage, chemistry of transformations in BaO– B2O3 – C ironless system was considered using the carbothermic method. A complete thermodynamic analysis of chemical interactions in this system was performed in the temperature range of 1400 – 3000 K. Possibility of the formation of a condensed metal phase due to boron carbides (B4C) and barium (BaC2 ), as well as barium hexaboride (BaB6 ) is shown. The obtained data can serve as the basis for creation of a new ferroalloy simultaneously containing boron and barium.