Laboratory experiments on thermal segregation in the melt of industrial pyrrhotite and nickel concentrates were performed. Grinding and magnetic separation of the pulp allowed to separate the product into magnetic alloy and separation tailings. The yield of magnetic alloy amounted to 50-60%, and the extraction of components in it reached, %: Ni 90-94; Co 92-94; S 5-6. The technological scheme is proposed, which allows to convert more than 90% of iron from circulating converter slag into low-sulfur matte during smelting, and then, during magnetic-flotation separation of cooled matte, to remove iron together with sulfur as a poor sulfide product. By processing about 1 mln tons/year of nickel concentrate, sulfur dioxide emissions into the atmosphere can be reduced by 440kt/year compared to the existing technology.