Effect of Gamma Irradiation on Phosphorus Removal from an Algerian Iron Ore of Gara Djebilet

Phosphorus, along with other undesirable elements, is an extremely deleterious constituent present in iron ores utilized as the raw material in the steel production process. It is responsible for increasing the hardness and brittleness of steel while reducing its ductility. The iron ore of Gara Djebilet has been the subject of several dephosphorization and enrichment studies. In this work, we are tested a new method for the dephosphorization of iron ore, which consists of irradiated ore with gamma irradiation, which possesses sufficient energy to potentially cleave the bonds between iron and phosphorus. Thermal pre-treatment can improve the efficacy of dephosphorization, we chose to roast the samples at 800°C followed by leaching with sulfuric acid. Mineralogical analyses including XRF, XRD, SEM and UV spectroscopy were conducted to identify the mineralogical phases. To optimize the parameters influencing the treatment and reduce the number of experiments, a Box-Behnken design of experiments was implemented and allowed assessment of the technique's efficacy. The treatment parameters optimized in this work were roasting temperature (300-800°C), sulfuric acid concentration (0.2-1N) and gamma irradiation dose (20-100 kGy). The two measured responses were the phosphorus removal percentage and iron enrichment percentage. The irradiated iron ore was leached with sulfuric acid solution after roasting the iron ore at the appropriate temperature. The optimization results confirm the model is significant. The optimal conditions proposed by the model for Gara Djebilet iron ore dephosphorization within the selected ranges are: a roasting temperature of 800°C, 0.6 N sulfuric acid and an irradiation dose of 100 kGy. Gamma irradiation is enabled to reducing the roasting temperature, but also decreasing the concentration of sulfuric acid. However, the obtained dephosphorization rate remains appreciable at over 53%.