RESEARCH OF THE BORON INTERFACIAL DISTRIBUTION BETWEEN BORON-BEARING OXIDE AND METAL

Abstract

The thermodynamic calculations have been performed to study the influence of silicon (0.1 – 0.8 %), aluminum (0.005 %) and carbon (0.1 %) contained in the metal on recovery process of boron from slag with the basicity equal to 5, at temperatures of 1400 – 1700 °C with the help of software package HSC 6.1 Chemistry (Outokumpu). The experiments of interfacial distribution of boron between slag system of СаО – SiО 2 – MgO – Al 2 O 3 – B 2 O 3 and metal have been carried out in a high temperature electrical resis­tance furnace of Tamman. The low-carbon steels with different con­tents of silicon were the base metal. The results of thermodynamic modeling and experimental data have shown that direct microalloy­ing of steel with boron are crucially possible due to boron reduce with the help of silicon in metal. The reduction of boron with slag is possible with the help of silicon in metal and the process was theo­retically based and experimentally studied. The results of thermody­namic modeling indicate the possibility of thermodynamic recovery of boron from the system of СаО – SiО 2 – MgO – Al 2 O 3 – B 2 O 3 with the help of silicon, despite its low (0.1 – 0.8 %) concentration in the metal. The increase of the initial silicon content in the steel increases the concentration of boron in the reduced metal. The results have shown the effect of silicon content and temperature of metal on the content of boron in steel. It has been shown that an extract of the metal by slag, containing 4.3 % B 2 O 3 , is accompanied by boron reduction. The primary reductant of boron is silicon, whose content in the metal after the experiment is reduced by 15 – 22 %. Thus, the steel sample with high concentration of silicon contains greater amount of boron. Recovery rate of boron ranges from 5.8 to 6.9 %, it is essentially correlated with the results of thermodynamic mod­eling. The concentration of boron in the metal can be controlled by changing temperature of process and content of silicon in the steel. The research results can be used in the development of the process technology of direct steel microalloying with boron.