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Oxidation Kinetics of Mixed Copper-Iron Sulfide at 1173 K

1984; Japan Institute of Metals and Materials; Volume: 25; Issue: 7 Linguagem: Inglês

10.2320/matertrans1960.25.487

2432-4701

Z. Asaki, Masahiro Tosa, Teruo Tanabe, Yoshio Kondo,

Metal Extraction and Bioleaching

Oxidation of a dense Cu–Fe sulfide sample composed of a mixture of bornite (Cu5FeS4) and troilite (FeS) was investigated in a N2–O2 gas mixture at 1173 K. The oxygen partial pressure in the gas mixture was between 1.0×103 and 5.0×104 Pa. In the initial stage of oxidation, iron was preferentially oxidized to form magnetite, and the rate of oxidation was controlled by mass transfer of oxygen through a gas boundary film on the sample surface. When the partial pressure of oxygen was higher than 1.0×104 Pa, the oxidation proceeded in accordance with the parabolic rate law at the later stage of oxidation, and a dense Fe3O4 film was formed. At the oxygen partial pressure lower than 5.0×103 Pa, the oxidation was accompanied by the evolution of SO2 gas at the later stage, and porous oxide was formed. During the oxidation, the sulfide was partly melted. Temperature variation of the sample during the oxidation was also studied.