Dephosphorization of high-phosphorus iron ore by direct reduction of hydrogen-rich gases and melting separation

Abstract

This study developed a direct reduction route to smelt refractory high-phosphorus iron ores by using hydrogen-rich gas. The effects of temperature, gas composition, and gangue on the reduction behavior of iron ore pellets were investigated. Additionally, the migration behavior of phosphorus throughout the reduction-smelting process was examined. The apparent activation energy of the reduction process increased from 64.2 to 194.2 kJ/mol. Increasing the basicity from 0.5 to 0.9 increased the metallization rate from 85.9% to 89.2%. During the reduction process, phosphorus remained in the gangue phase. Carbon deposition and phosphorus removal behaviors of the pellets were investigated and correlated with the gas composition, temperature, pressure, metallization rate, and basicity. Increasing the FeO and CaO contents led to an increase in the liquidus temperature. A high metallization rate of the pellets reduced the phosphorus removal rate but increased the carbon content of the final iron product. Increasing basicity restricted the migration of phosphorus and improved the rate of phosphorus removal. The optimum dephosphorization parameters were separation temperature of 1823 K, basicity of 2.0, and metallization rate of 82.3%. This study presents a high-efficiency and low-carbon method for smelting high-phosphorus iron ores.

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