| 摘要 |
The invention relates to a method for purifying metallic silicon by (1) float-and-sink separation of ground silicon, using a heavy separation fluid, such as 1,1,2,2-tetrabromoethane, methylene bromide or bromoform in conjunction with a diluent, (2) bleaching of the purified product of step (1), in particular with hydrochloric acid at elevated temperatures, and (3) melting of the silicon (purified by steps (1) and (2)), the molten silicon being brought into contact with (a) a gas which oxidises impurities, such as a mixture of Freon-12 and oxygen and (b) a slag on the basis of silicon dioxide, for example a mixture of SiO2, CaO and CaF2. By means of this method according to the invention, a hyperpure silicon is obtained which is suitable for semiconductors, electronic, photovoltaic and metallurgical applications. <IMAGE>
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