Thermal Decomposition Kinetics of Small‐Particle Limestone at Converter Smelting Temperature

To optimize the slag‐forming process during steelmaking via limestone particles injection into the converter, the high‐temperature rapid calcination conditions of the converter are simulated by using a high‐temperature resistance furnace, and the thermal decomposition kinetics of small particle sizes of limestone (≤5 mm) are investigated in this work. Seven groups of particles with characteristic sizes (<0.075−5.7 mm) are tested using an isothermal calcination method and a thermal analysis kinetic model. Results show that the decomposition rate increases significantly with temperature (1300°C–1500°C). Furthermore, particle size nonlinearly influences decomposition kinetics. Particles between 0.18 and 1.0 mm (20–100 mesh) exhibit the fastest conversion rate, forming highly active CaO after only 60 s of calcination. In contrast, particles smaller than 0.075 mm may experience a reduced reaction rate due to agglomeration. Kinetic analysis indicates that particles below 100 mesh follow a three‐dimensional phase boundary reaction model with activation energies of 21.34–72.56 kJ mol −1 , while those above 100 mesh conform to a two‐dimensional model with activation energies of 26.04–36.43 kJ mol −1 . This study provides a theoretical basis for particle size selection and parameter optimization in converter limestone injection.