A process for the production of a metal mixture composition containing lead and tin, and comprising by weight at least 10% tin and 45% lead, at least 90% of tin and lead together, more lead than tin, from 1-5000 ppm of copper, at least 0.42% antimony and at least 0.0001% wt of sulphur, at most 0.1% of the total of chromium, manganese, vanadium, titanium and tungsten, and at most 0.1% of each one of aluminium, nickel, iron and zinc. The process includes a pre-treatment step for producing the metal mixture composition, followed by a vacuum distillation step wherein lead is removed by evaporation and a bottom stream is obtained comprising at least 0.6% wt of lead.