Distribution of Iron and Boron Between Silicon Metal Smelting Products in Industrial Saf using Borate Fluxes

Abstract

The article identifies the key sources of iron and boron impurities entering silicon metal under industrial smelting conditions in Submerged arc furnace (SAF). Impurity rocks in the composition of quartz, the main raw material for the production of silicon metal, were studied using the X-ray fluorescence method, and their visual classification was carried out. It has been established that the energy of secondary characteristic x-ray radiation (CXR) for boron and iron contained in the feedstock is 3.1 and 6.3 keV, respectively. A relationship was found between the intensity of CXR pulses and the concentration of iron and boron impurities. The features of the distribution of these elements between metallurgical phases (silicon metal, slag and gas phase) when used in the smelting process with and without borate flux (colemanite) have been established. Under industrial conditions, it has been established that the transfer coefficient of boron into silicon metal is reduced when using borate flux from 76.3% to 58.36%. The transfer of iron into silicon metal from the charge remains at the same level with a slight downward trend from 93.18% to 92.12%. This may be explained by a reduction in the contact time of the molten slag accumulating on the bottom with liquid silicon metal. There is also a reduction in the consumption of charge materials when using colemanite from 6.07 to 5.635 t/t of silicon metal due to the reduction in the time of cleaning the smelting bath from viscous slag accumulated on the bottom.