To make it possible to separate and recover an Ni-Si based alloy and metallic Sn by adding an SiO2-contg. material and a reducing agent to a solder-contg. nickel alloy and subjecting the mixture to reduction melting in a a specific temp. range under a strong reduction atmosphere under which Si is stable.

The SiO2 component, such as silica stone, as an Si source and coke, etc., as the reducing agent are added to the solder-contg. nickel alloy and the mixture is sufficiently mixed and is charged into a graphite crucible. This graphite crucible is heated in a temp. range of ≥1400 to ≤1600°C under the strong reduction atmosphere under which the Si is stable in a high-frequency induction heating furnace to melt and reduce the mixture. At this time, the Si grade in the Ni-Si based alloy is preferably controlled to 15 to 35 wt.%, more preferably 30 to 35 wt.%. When the melting and reducing of the mixture ends, the mixture is held at the prescribed temp. and is then cooled to cause phase sepn. As the result, the Ni-Si based alloy of a low Sn grade and the high-grade Sn are separated and recovered at a high yield. Particularly the Si grade in the Ni-Si based alloy is controlled to 30 to 35 wt.%, by which the Sn grade is confined to about ≤3%.