Iodination of Aluminothermic Silicon Produced From Quartz Glass and Silumin with Obtaining High-Purity Silicon

摘要

At obtaining pure silicon it is important to use raw materials with low content of impurities. The quartz glass contained 99.5-99.94% of SiO_2 can be applied as such. The given article contains the research results of obtaining pure silicon from opaque quartz glass (99.5% of SiO_2) and silumin (90% of Al; 9.64% of Si and 0.34% of impurities) with the subsequent iodination of aluminothermic silicon and pyrolysis of silicon iodides. The researches have been performed with use of a software package HSC-5.1 based on the Gibbs energy minimization and the second order rotatable method of planning an experiment with the subsequent optimization of the process conditions. It was found, that iodination of the aluminothermic silicon produced at the interaction of opaque quartz glass contained 99.5% of Si and silumin is accompanied by the full transition of the Si in a gas phase at 980-1,100℃ (P=0.1-0.77 bar), titanium - at 966-1,065℃ (P=0.1-0.92 bar), iron - at 1,005-1,028℃ (P=0.1-1 bar), manganese - at 1,030-1,100℃ (P=0.1-0.73 bar), copper - at 954-1,040℃ (P=0.1-0.92 bar), aluminum and magnesium - at 800-1,100℃ (P=0.1-1 bar), calcium - at 900-1,100℃ (P=0.1-1 bar). At heating the iodide gas phase to 1,700-1,900℃ (pressure is 0.1 bar) occurs formation of the silicon with purity of 99.8061-99.8097%; basic impurities of this silicon are Fe - 0.108-0.112%, Ti - 0.0515-0.0534%, the increase in pressure to 1 bar lowers purity of the silicon to 99.6719-99.7681%.