Dear Amine,

Thank You for you reply,

Is the granular phase as granular I assume?

---Yeah granular phase is granular

How many phases are now included?

---Two phases solid(Fe2O3 and Fe) and gas(CO and CO2)  , total 4 species

I will go with only two phases and perhaps think about DDPM if dense.

---Ok, I will try to solve with DDPM .