Kinetic investigation on the reduction of iron concentrate-charcoal composite briquette by forced stepwise isothermal analysis (FSIA)

Flotation tailings of the zinc processing plant contain a high amount of iron. Recovery of iron from these tailings is a promising approach to reduce process waste and provide the steel industry's raw material. This study investigated the reduction kinetics of self-reducing briquettes composed of fine hematite particles and iron concentrate; a material obtained from processing zinc tailing by magnetic separation. The investigation was performed using the forced stepwise isothermal analysis method, and mass loss data from 973 to 1373 K was provided by the reduction of the briquettes in a thermogravimetric scale. The addition of iron concentrate as part of the raw material showed an increase in the reduction rate compared to briquettes composed of pure hematite. In the temperature range of 973-1073 K, the reduction was controlled by nucleation, with an activation energy of 327.60 kJ mol(-1), and from 1123 to 1223 K by diffusion, with an activation energy of 402.3-665.0 kJ mol(-1). For a batch process, as performed in the TG analysis, the gasification of charcoal was a step that increased the apparent activation energy of the process.

Automated summary

This study investigated the reduction kinetics of self-reducing briquettes composed of fine hematite particles and iron concentrate obtained from processing zinc tailings. The results showed that the addition of iron concentrate increased the reduction rate, and the reduction process was mainly controlled by nucleation or diffusion at different temperature ranges.