2018-Sustainable Industrial Processing Summit
SIPS2018 Volume 1. Afonso Intl. Symp. / Iron and Steel Making
| Editors: | F. Kongoli, M.-C. Gomez-Marroquin, M. Contrucci, N. Lacerda, F. V. Cancado, M. de Souza, R. Valladares |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2018 |
| Pages: | 184 pages |
| ISBN: | 978-1-987820-82-9 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Impact of Raw Materials on Production and Refining of Silicon
Vishu Dosaj1;1DOW CORNING CORPORATION, Midland, United States;
Type of Paper: Regular
Id Paper: 400
Topic: 2
Abstract:
In the production of silicon, quartz is reduced with carbon in an arc furnace. During the selection of a plant site, key considerations include availability of high quality quartz, source of carbon such as charcoal and or low ash high reactivity bituminous coal, and wood chips. Quartz quality requires adequate thermal strength and impurities namely alumina, iron oxide and titanium. High alumina levels in quartz not only impact the silicon production but also require creative refining. The supplies of low ash coal suitable for silicon production are limited. Such coals are available in United States and to some extent in Europe. Charcoal is widely used in South America but not so in Europe and USA.
The furnace operating strategy depends on the raw material type, and size of the furnace. The operating strategy with coal and charcoal based raw material mix is discussed and recommendations are made for operating variables namely, furnace operating resistance and electrode current to complement the raw material mix. The size of raw materials and the fines content also has a significant impact on process efficiency. The furnace size also impacts process efficiency requiring attention to details with increasing furnace size. Typically the furnace efficiency drops as the furnace size exceeds 20 MW load.
Silicon refining process is a function of tap temperature, tap chemistry (with respect to Al and Ca), silicon flow rate, tap weight and the amount of slag from the tap hole. Taking into account the refining conditions, the refining strategy is discussed to increase in specification product and at the same time reduce scull losses and improve ladle life.