Quartz-Cristobalite Transformation and Its Effect on Reactions in Si Production: Initial Studies
In Si and FeSi production, the main Si source is SiO2, in the form of quartz. Reactions with SiO2 generate SiO-gas that further reacts with SiC to Si. During heating, quartz will transform to other SiO2 modifications with cristobalite as the stable high temperature phase. Transformation to cristobalite has been investigated and shown to be a slow process where the rate varies between the investigated quartz types.
The effect of quartz versus cristobalite as SiO2 source has been studied for reaction (1) 2SiO2 + SiC = 3SiO + CO, by heating of pellets with SiO2 + SiC in Ar-gas. The reaction was faster with cristobalite than with quartz. Initial experiments indicates that this is the case only in Ar and not in CO-atmosphere The higher specific surface area of cristobalite is believed to contribute to the higher rate. The industrial consequences of the observed difference between quartz types are discussed.
Keywordssilicon quartz cristobalite reaction rates
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- 1.A Schei A., J K Tuset J.K., and H. Tveit, “Production of High Silicon Alloys”, Tapir forlag, (Trondheim, Norway, 1998), ISBN: 82–519–1317–9.Google Scholar
- 2.Kjell Wiik, “Kinetics of reactions between silica and carbon” (PhD thesis, NTNU Trondheim, Norway 1990), IUK report 1990:60; ISBN: 82–7119–170–5.Google Scholar
- 3.Kurt Aasly, “Properties and behavior of quartz for the silicon process” (PhD thesis, NTNU Trondheim, Norway, 2008).Google Scholar
- 5.Vegar Andersen, “Investigation of thermal properties of quartz for the silicon industry under reducing atmosphere”, (NTNU Project work in TMT 4500, Trondheim, Norway, 2009).Google Scholar
- 6.Dian Adisty, “Influence of Holding Time on Solid-Solid Reaction between quartz + SiC and Cristobalite + SiC”, (NTNU Report, Trondheim, Norway, 2012).Google Scholar
- 7.Dian Adisty, “Kinetics study of silicon production from different polymorphs of quartz”, (NTNU Project work, TMT 5500, Trondheim, Norway 2012).Google Scholar
- 8.Bjørn Eske Sørensen and Sebastian Vedeler, “Preliminary study to quantify amorphous silica with X-Ray Diffraction”, (NTNU report 228.11.11, Trondheim, Norway 2011).Google Scholar
- 9.Dian Adisty, “Kinetic Study of SiO2 + SiC Reaction in Silicon Production”, (MSc thesis, NTNU, Trondheim, Norway, 2013).Google Scholar