Evaluation of the Acid Baking Technique

Unlike the available mineral resources, the steelmaking processes have demanded raw material with lower phosphorus content to decrease the costs, energy use, and the residue generated within the steel plant. One alternative is to develop pretreatment of the iron ore concentrates producing raw materials with lower phosphorus. This study proposes a treatment using microwave heating combined with a dilute aqueous solution of sulfuric acid, followed by quenching during leaching with water, as an efficient route for phosphorus removal from iron ore. A design of experiment (DOE) was performed to investigate the optimal conditions for heating and leaching that maximize the rate of phosphorus removal. The structure of the treated iron ore particles was observed by scanning electron microscopy (SEM). Results indicated that an average heating time of 10 minutes, a crack size of approximately 20µm, and a leaching time of 8 minutes are adequate to achieve phosphorus content below 0.01%. Moreover, under the most favorable combination of heating and leaching conditions proposed in this study, the phosphorus content in the iron ore samples could be completely removed, demonstrating the viability of this technique for enhancing the quality of iron ore for steelmaking.