Oxidation Roasting, Gas-based Reduction Followed by Magnetic Separation of a High Phosphorus Iron Ore in Africa

This is an article in the field of metallurgical engineering. In view of the problems of low compressive strength and high reduction temperature in the gas-base reduction of a high-phosphorus iron ore, a new process of oxidation roasting, gas-based reduction followed by magnetic separation was proposed. The effect of oxidation temperature and the types and dosages of dephosphorization on the compressive strength of the oxidized pellets were investigated, and the conditions of oxidation roasting that met the strength requirements of the shaft furnace were found. On this basis, the effects of reducing temperature, total reducing gas flow rate, reducing gas composition and reducing time on iron recovery and dephosphorization were studied. The results showed that under the conditions of 10% Na₂CO₃ dosage, oxidation temperature 1200 ℃, oxidation time 60 min, reduction temperature 950 ℃, flow rates of H₂ and CO were 3.75 L/min and 1.25 L/min, respectively, and reduction time 180 min, Iron grade, iron recovery and phosphorus content were 91.15%, 93.07% and 0.14%, respectively. The SEM results show that the phosphorus in the powdered reduced iron exists in the form of mechanical inclusions, and the phosphorus is removed by grinding-magnetic separation.