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.