Semicontinuous process for the manufacture of pure silicon
AssigneeHelictronic Forschungs- und Entwicklungs- Gesellschaft fur Solarzellen-Grundstoffe mbH
InventorsJosef Dietl, Claus Holm, Erhard Sirtl
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Abstract
Pure silicon is obtained in a cyclic process by reducing quartz sand with aluminum; the finely divided quartz is dissolved in an aluminum sulphide slag and is reduced by molten aluminum. The molten aluminum also serves as a solvent for the elemental silicon which crystallizes out and precipitates as the temperature falls. Aluminum oxide formed during the reduction is extracted from the slag and passed on for melt electrolysis in order to recover the aluminum.
Claims8
A semicontinuous process for the manufacture of silicon from quartz sand by reduction with aluminum, comprising the steps of:
- introducing quartz, batch-wise and while being stirred, into a closed reaction vessel containing molten aluminum sulphide in addition to aluminum;
- periodically removing aluminum, enriched by the elemental silicon that forms, said aluminum then being slowly cooled to a minimum temperature of approximately 600.degree. C., and being separated from the precipitating silicon;
- and
- removing the aluminum oxide, formed during the reaction, from the aluminum sulphide melt, said aluminum oxide then being separated from adhering aluminum sulphide melt.
Dependencies are inferred from the claim text.