verfahren und herstellung von silicium oder in einem ferrosilicium elektroniederschachtofen und fur das verfahren geeignete rohstoff - formlinge

摘要

A process for the production of silicon in a low-shaft electric furnace, in which raw-material blanks are first formed which contain fine-grain silicon dioxide, e.g. in the form of sand, and carbon in excess in respect of the reduction to silicon carbide and the raw-material blanks are introduced into the low-shaft furnance as a charge in mixture with silicon dioxide in lump form. The silicon dioxide in the raw-material moldings is reduced to silicon carbide in an upper part of the low-shaft electric furnace at a temperature of below 1600 DEG C. and coke structure agglomerates are formed from the excess carbon of the raw-material moldings. In a lower part of the low-shaft electric furnace, the silicon dioxide in lump form, is reduced to silicon with silicon carbide and carbon from the coke structure agglomerates at a temperature of above 1600 DEG C., preferably from 1800 DEG to 200 DEG C. The raw-material moldings are formed with bituminous binder containing a fine-particle silica powder. The silicon carbon reduction results in coke structure agglomerates having a very large internal carbon area in accordance with the internal area and percentage proportion of silica powder in the raw-material moldings. The silicon dioxide and gaseous silicon monoxide are reduced with the coke structure agglomerates having the increased internal area.