Mixtures of copper concentrate and silica sand with various CuFeS₂/FeS₂ ratios and with 5 mg in weight were dropped from the top side of the silica tube filled with O₂ gas and were reacted at 470℃. The Fe/SiO₂ mass ratio of the mixtures was fixed at 1.1 as a typical composition of flash smelting. The samples exhibited the white light emission expecting the arrival temperature of > 1500℃ due to the ignition reaction of sulfide minerals. Reaction products were evaluated by using scanning electron micrograph-energy dispersive X-ray spectrometry (SEM-EDS) analysis. In addition to un-reacted oxide and sulfide particles, matte-slag-mineral-magnetite coexisted particles were recognized in microstructure observation. The products supported heterogeneous reactions occurring in the copper concentrate burner. The effect of FeS₂ concentration on copper concentration in matte phase and magnetite phase fraction in slag phase was discussed.