Two-stage synthesis of spherical iron powders from steel industry by product

Abstract

Spherical iron powders are often used in high end applications like metal injection molding additive manufacturing, and soft magnetics due to their sphere morphology, high density and good flowability. Till date, manufacturing processes like gas atomization and carbonyl process are the only available routes for synthesis of spherical iron. In this work a novel approach of obtaining spherical iron powder via a two stage (reduction + plasma spheroidization) process by use of iron oxide by-product from steel industry is proposed. Physico-chemical characterization of powders reveals that irregular iron powders with high purity (Fe (T)- 98.2 wt%, Fe(M)- 96.8 wt%), low apparent density (1.1 g/cc) and high surface area (0.37 m²/g) are successfully synthesized at optimal conditions of reduction (850 °C, 300 min). Further, plasma spheroidization of this irregular iron powders at optimized process parameters (11.5 KW plasma power, 6.5 g/min feed rate) generated spherical powders with high purity (Fe (T)- 97.8 wt%, Fe(M)- 95.6 wt%), high apparent density (3.84 g/cc) and good flowability (8.8 s/50 g). Present work fosters a sustainable and scalable approach for synthesis of two different grades of iron powder having diverse applications from a single feed source.