Abstract: The invention relates to a method to produce blister copper or high grade matte in a smelting reactor directly from a sulfidic copper concentrate containing material and/or finely ground copper matte, whereby oxygen-containing gas, copper concentrate and/or finely ground copper matte are fed into the reactor. According to the invention CaO and SiO2 containing flux is fed into the smelting reactor along with oxygen-containing gas, copper concentrate and/or copper matte, and part of the copper in the concentrate and/or in the matte is oxidized in order to form a slag in which the CaO/SiO2 ratio is higher than 1.5, and in which the copper content is in oxidized form, and in which the lime content calculated in a CaO+SiO2+FeOx=100 system is higher than 20%.