Optimization of Hydrogen Utilization and Process Efficiency in the Direct Reduction of Iron Oxide Pellets: A Comprehensive Analysis of Processing Parameters and Pellet Composition

The article deals with the H-2 consumption for different processing conditions and the composition of the processed pellets during the direct reduction process. The experiments are carried out at 600-1300 degrees C, with gas pressures of 1-5 bar, gas flow rates of 1-5 L min(-1), and basicity indices of 0 to 2.15. Pellets with different compositions of TiO2, Al2O3, CaO, and SiO2 are analyzed. The gas flow rate is crucial, with 0-10 L min(-1) leading to an H2 consumption of 0-5.1 kg H-2/kg pellet. The gas pressure (0-10 bar) increases the H-2 consumption from 0 to 5.1 kg H-2/kg pellet. Higher temperatures (600-1300 degrees C) reduce H-2 consumption from 5.1 to 0 kg H-2/kg pellet, most efficiently at 950-1050 degrees C, where it decreases from 0.22 to 0.10 kg H-2/kg pellet. An increase in TiO2 content from 0% to 0.92% lowers H-2 consumption from 0.22 to 0.10 kg H-2/kg pellet, while a higher Fe content (61-67.5%) also reduces it. An increase in SiO2 content from 0% to 3% increases H-2 consumption from 0 to 5.1 kg H-2/kg pellet. Porosity structure influences H-2 consumption, with the average pore size decreasing from 2.83 to 0.436 mm with increasing TiO2 content, suggesting that micropores increase H-2 consumption and macropores decrease it.