GB484637A - Improvements in and relating to the production of silicon iron - Google Patents

Abstract

Silicon for use in the production of silicon iron is purified by melting it in a quartz crucible under reduced pressure to remove hydrogen. If it contains oxygen and nitrogen, calcium or one of the rare earth metals, such as cerium, may then be added, the excess being distilled off.ALSO:In a process for producing silicon iron, particularly one containing approximately 3 to 5 per cent of silicon, the iron is first melted alone, then decarbonized by adding one or more readily reacting oxides, then, after removal of any undesired constituents which may have entered the melt, is deoxidized, after which the silicon is added to the molten iron, the whole of the operations being carried out in the aforesaid sequence and under reduced pressure. Iron oxide or manganous oxide may be used for the decarbonization, the excess of manganese being in the latter case subsequently distilled off. The deoxidation may be performed by a hydrogen atmosphere or by passing hydrogen through the melt; alternatively one or more metals of the second group of the periodic system, especially calcium or beryllium, may be added, the excess being distilled off. One or more of the rare earth metals especially cerium may be employed for deoxidation, instead of, or in addition to hydrogen or calcium, the excess being distilled off. Copper up to 1 per cent may be added. The silicon may be purified before adding it to the iron, for example by melting it in a quartz crucible under reduced pressure to remove hydrogen. If it contains oxygen and nitrogen, calcium or one of the rare earth metals, such as cerium, may then be added, the excess being distilled off. In order to enable the additions to the molten iron to be made without breaking the partial vacuum, the substances to be added may be contained in a vessel disposed in the melting chamber and having a valve at the bottom which can be operated from outside.