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

Abstract

The article deals with the H₂ 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 °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 H₂/kg pellet. The gas pressure (0–10 bar) increases the H₂ consumption from 0 to 5.1 kg H₂/kg pellet. Higher temperatures (600–1300 °C) reduce H₂ consumption from 5.1 to 0 kg H₂/kg pellet, most efficiently at 950–1050 °C, where it decreases from 0.22 to 0.10 kg H₂/kg pellet. An increase in TiO₂ content from 0% to 0.92% lowers H₂ consumption from 0.22 to 0.10 kg H₂/kg pellet, while a higher Fe content (61–67.5%) also reduces it. An increase in SiO₂ content from 0% to 3% increases H₂ consumption from 0 to 5.1 kg H₂/kg pellet. Porosity structure influences H₂ consumption, with the average pore size decreasing from 2.83 to 0.436 mm with increasing TiO₂ content, suggesting that micropores increase H₂ consumption and macropores decrease it.