Improving property of reduced iron powders by ultrapure magnetite pellets

To address the issues of low process efficiency, high energy consumption, and significant pollution in the traditional Hoganas method for producing reduced iron powder, reduced iron powder for powder metallurgy was prepared using ultrapure magnetite pellets with various compressive strengths by coal-based reduction-hydrogen reduction method. The results show that pellets with compressive strength of 2500 N/pellet ultimately produce a powder metallurgy iron powder with iron grade of 98.24%, hydrogen loss of only 0.5%, bulk density of 2.38 g cm^-3, fiow rate of 35.97 s (50 g)^-1, and compressibility of 6.41 g cm^-3 after reduction for 12 h at a C/Fe mass ratio of 2 and a temperature of 105 C, followed by crushing, fine grinding, and secondary hydrogen reduction at 800 ℃ for 2 h, meeting the standard for FHY100·240. As the compressive strength of ultrapure magnetite pellets increases, the aggregation of metallic iron grains in the reduced pellets intensifies, the porosity of the pellets decreases, and the structure densifies, resulting in a significant increase in the bulk density of reduced iron powder.