The increasing amount of silicon waste generated from the rapid developing photovoltaic industry calls for an economical silicon recycling process. The present work proposes a facile process with which silicon waste and ironmaking slag containing TiO2 were used as raw materials to produce titanium silicides, a promising high added value material. The process was experimentally investigated in lab scale. The result shows that a high CaO/SiO2 ratio in slag promotes the reaction. TiSi2 and Ti5Si3 could be synthesized as principal products within 0.5 and 3 h with CaO/SiO2 = 1.31 in mass, respectively. CaO-SiO2 slag was produced as byproducts. Kinetic analysis indicates that silicon diffusion in slag is the rate-determining step of the reaction process. The reaction rate constant is around 1.0 × 10-4 s, and the effective diffusion film thickness in slag side is around 10-3 cm at the silicon-slag interface. Slag basicity is suggested to increase to 1.31 for a faster silicon diffusion and further promotion of the reaction rate.

Original languageEnglish
Pages (from-to)7078-7085
JournalACS Sustainable Chemistry and Engineering
Volume6
Issue number5
DOIs
Publication statusPublished - 2018

    Research areas

  • Kinetic analysis, Photovoltaic, Recycling, Solar cells, Titanium silicides

ID: 45172769