This paper presents the results of research into the production of high-grade solders from tin-containing slag recycled from the melt. Excess copper is removed by filtering the rough solder over a specific temperature range, yielding POS61 solder. The resulting filter residue is used for alloying gray cast iron. To produce lead-free solders, lead is removed by mixing SnCl2 into the melt at a 10:1 ratio. Regeneration of the resulting salt slag to extract SnCl2 and reuse it is carried out using fractional crystallization in water, taking into account the different solubility of SnCl2 and PbCl2 at low temperatures.