Evaluation of the Acid Baking Technique to Decrease the Phosphorus Content of the Iron Ore

Abstract

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. Depending on the mineral structure, a heat treatment combined with leaching could be an efficient way to achieve concentrates with low phosphorus (less than 0.01%), suitable for steelmaking processes. A fast and efficient way of applying energy to iron ore particles is the use of microwave to heat the particles. Thus, we propose a treatment using microwave heating while mixing with a dilute aqueous solution of sulfuric acid, followed by quenching during leaching with water, as a feasible route for the phosphorus removal from iron ore particles. We performed a design of experiment (DOE) to investigate the optimal conditions of heating and leaching, which maximize the rate of phosphorus removal. The structure of the iron ore particles after their treatment with microwave energy was observed by scanning electron microscopy (SEM). Thus, we analyze the optimal conditions for heating and leaching, the structure of the iron ore particles and which mechanism and rate equations are controlling the phosphorus removal. The results indicated that the average heating time is 10 min, the size of the crack of the order of 20µm and a leaching time of 8 min are adequate to achieve less than 0.01% of phosphorus. We demonstrated that under the most favorable combination of conditions for heating followed by leaching proposed in this study, the removal of the phosphorus content in the iron ore samples could reach 100%.

Evaluation of the Influence of Particle Size in the Acid Baking Process for the Reduction of Phosphorus Content in Iron Ore

“…The results presented and discussed in this paper are in accordance with those reported by Silva et al [21][22][23] and Silva 23 , where it was observed that after the pretreatment with the microwave energy, the same decrease in the tendency of the diffusional control in the iron ore particles to the particles of the same granulometry without the occurrence of pretreatment 23 . This fact demonstrates that with the decrease of the mean value of granulometry, also occurs the decrease of the diffusional control.…”

Analysis of the Microwave Heating Effect in the Comminution Efficiency of Iron Ore Particles

“…However one of the most important benefits in the treatment of iron ore to microwave energy consists in the release of particles into larger granulometric size thus decreasing the wear of the grinding equipment in the plant [12]. Compared with conventional methods, pre-treatment using microwave energy consumes lower amounts of energy, improves the performance of grinding and phosphorus removal and reduces the processing time [13].…”

Analysis of the Carbothermic Reduction of Iron Ore-Coke Composite Mixtures by Microwave Heating

“…The application of microwave energy in the steel industry encompasses studies from the treatment of ores [18][19][20] and attempts to design a furnace for obtaining pig iron 21,22 to the recovery of the metallic load from steel residues 23 and also the treatment and effects of microwave irradiation on blast furnace slag 24,25 . However, the main results come from kinetic tests of carbothermic reduction of iron ore and carbon-rich material mixtures.…”