Silicothermic reduction method was applied to produce ferrosilicon which contains Mg and other alkali earth metals and which is a powerful nodularizer of graphite in cast iron. Ferrosilicon was melted in a high frequency induction furnace using a MgO-lined crucible and treated by fluxes of powdered MgO CaO, SrO, BaO or CaCO_3+MgCO_3. Mg content of the ferrosilicon increased with the reaction temperature. Contents of other alkali earth metals were approximately in proportion to their boiling points. The nodularizing characteristics of the ferrosilicon were compared by examining the cast iron treated by them microscopically. The fading tendencies of nodularizing action were evaluated indirectly from the effect of the holding time after inoculation on the chilling depth of gray cast iron treated by various ferrosilicon and calcium silicide. From the results of these tests, it was concluded that the ferrosilicon containing small amounts of Mg and Ca reduced from their oxides can be used as an effective nodularizer for cast iron
