Mechanism of lime decomposing Al2O3-containing fayalite melt
A method to upgrade the iron grade in copper slagwas proposed using lime to decompose Al2O3-containing fayalite melt (AFMT). Thermodynamic calculations indicated that adjusting the CaO/AFMT ratio can yield a residual melt with a FeO concentration of 75−88 wt.％ and produce Ca2SiO4. In-situ observations suggested that the reaction was impeded in some way. Quenching experiments revealed that the initial reaction products consisted of calcium ferrite compounds and FeO−CaO melt. At the FeO−CaO melt/AFMT interface,Ca2SiO4 particles precipitated,forming a dense Ca2SiO4 film that significantly impeded mass transfer. Although trace amounts of Al2O3 in AFMT temporarily enhanced mass transfer,they were insufficient to overcome this retardation effect. The decomposition reaction was far from achieving equilibrium,demonstrating a self-retardation effect. Measures must be implemented to eliminate this self-retardation effect and enhance the efficiency of reaction kinetics.
limeAl2O3-containing fayalite meltCa2SiO4 filmself-retardationmass transfer
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