Ferrosilicon-nitride purificn. - where treatment with chlorine gas produces high content of silicon nitride and low iron content

摘要

The Fe-Si-N contains by wt. 80-95% Si3N4 obtd. by the chlorination of Fe-Si-N obtd. in a conventional way. The initial Fe-Si-N powder is reacted at high temp. with Cl2 gas to produce ferric chloride, which is deposited cooled reactors. The chlorination pref. occurs at 200-600 degrees C, esp. 300-550 degrees C., for 20-80 mins. the reaction time and temp. being used to adjust the residual iron content of the purified Fe-Si-N obtd. Fe-Si-N contg. 65-98% Si3N4 is used as a less expensive alternative to Si3N4 in refractories employed e.g. in blast furnaces, but the high Fe content of the conventional material is undesirable. Fe-Si-N with a low iron content is produced at low cost without producing effluents causing pollution.