Evaluation of Ignition and Combustion Reactions of CuFeS₂ and Silica Stone Less Than 100 ms in a Drop Furnace

Abstract

The objective of this study was to understand the instantaneous ignition and combustion reactions of CuFeS₂/silica mixture by preheated oxygen gas blowing. The ignition initiation position of CuFeS₂ was controlled by installing a coiled heater inside the reaction tube of the drop furnace, and the ignition and combustion reactions of the CuFeS₂/silica mixture were evaluated by blowing preheated oxygen gas. The sample was mixed at a mass ratio of Fe/SiO₂ = 1.1. The combustive sample was observed by a high-speed camera. The microstructure of reaction products in water-quenched samples was evaluated using scanning electron microscopy-energy dispersive spectroscopy. Based on particle temperature measurements by a two-color temperature method, bright particles observed by ignition and reaction were classified into the following four types: (1) ones with a surface temperature of at ≥2000℃, (2) ones including two different temperature regions of 1600 and 1900℃, (3) ones with a uniform temperature at around 1500°C, and (4) ones at lower temperatures of ≤1300°C. The microstructural analysis revealed that the Cu/S ratio of the matte phase had an average composition of 3.6 near Cu₂S. The ratios of Cu/S and Fe/SiO₂ had no change within experimental errors in all collected particles consisting of slag and matte phases.