To make it possible to separate and recover an Ni-Si-Fe based alloy and metallic Sn by adding ferrosilicon to a solder-contg. nickel alloy in an inert atmosphere and melting this alloy in a specific temp. range.

The ferrosilicon is added as an Si source 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 inert atmosphere by gaseous N2 in a high-frequency induction heating furnace to melt the mixture. At this time, the Si grade in the Ni-Si-Fe based alloy is preferably controlled to 25 to 35 wt.% or the Si/Sn weight ratio to 1.1 to 1.4. The solder-contg. nickel alloy and the ferrosilicon are brought into sufficient reaction and the reaction product is held at a prescribed temp. and is then subjected to phase sepn. by cooling down to room temp. As a result, the Ni-Si; Fe based alloy of about 5% Sn is obtd. and the metal Sn may be recovered by elution.