<p>The input of FeS₂ and SiO₂ to flash furnaces has increased yearly with the recent trend toward lower grades of the copper concentrates. The influence of these coexisting materials on the concentrate’s combustion behavior was investigated. Samples made of copper concentrate, FeS₂ and SiO₂ were formed into tablet shape and burned. The sample temperature was measured using thermocouples embedded in the sample to characterize the combustion behavior. To evaluate the effect of FeS₂ and SiO₂ on concentrate combustion, the surface temperature and morphology of sample were also evaluated simultaneously using a high-speed IR camera. Even under conditions where CuFeS₂ alone would result in low-intensity combustion, there were cases where high-intensity combustion occurred in the case of copper concentrate. It was suggested that easily combustible substances like iron sulfide included in the concentrate could promote the combustion of the concentrate. When only FeS₂ was added to the concentrate, although the combustion intensity increased, the reaction product was in the solid phase. When various amounts of SiO₂ were added to this sample, there was optimal condition where the melt formed from the low temperatures and the combustion intensity was highest among these samples. When SiO₂ was excessive, SiO₂ remained unmelted and tended to inhibit combustion. It was revealed that the ratio of Fe to SiO₂ is very important even under the concentrate combustion. In addition, large SiO₂ also tended to lower the combustion intensity. Particle size of the silica flux also has a significant effect on concentrate combustion.</p> Graphical Abstract <p></p>