A Preheater-Steelmaking Furnace and closed loop Process System for semi-continuous melting of integrally preheated recycled or virgin ferrous charge, by using highly energy efficient combustion process of natural gas combusted by oxygen as the main heat source, after preheating of the cold charge, by fully exploiting thermal energies of the melting process off-gases, in a gas tight, low noise, ecologically friendly PSF with scant CO and drastically reduced CO2 in exhaust gases for semi-continuous, batch self-charging, sealed pairs of eccentrically rotating quasi cylindrical, permeable half drums hoppers creating separate preheating chambers.