An ore containing 76 mol% iron pyrites (FeS2) and 24% solid inert is roasted in the presence of dry air at 500 °C and 1 atm. The following reactions take place:
2 FeS2(s) + 15/2 O2 (g) → Fe2O3(s) + 4SO3 (g) (1)
2 FeS2(s) + 11/2 O2 (g) → Fe2O3(s) + 4SO2 (g) (2)
Dry air is fed to the furnace in 25% excess of the amount theoretically required to oxidize all the sulfur in the ore to SO3. An FeS2 oxidation of 80% is obtained, with 40% of the FeS2 converted forming SO2 and the rest forming SO3. A gas stream and a solid stream leave the roaster. Calculate the molar composition and volumetric flow rate of the gas leaving the roasting oven per kmol of ore roasted, assuming
i. ideal gas behavior
ii. compressibility factor equation of state
iii. SRK equation of state (assume that Kay's rule can be used to approximate ω for the mixture, and ωSO3 ≈ ωSO2)