Phosphorus removal of oolitic high-phosphorus iron ore using biomass char

A method of phosphorus removal was proposed to process oolitic high-phosphorus iron ore. It is an integration of direct reduction and melting separation with carbon-containing pellets prepared with high-reactivity biomass char. Direct reduction experiments were performed in a tubular furnace, and three parameters were investigated, i. e., reduction temperature, biomass char adding ratio (carbon-to-oxygen molar ratio) and atmospheres. The optimum condition was determined to be the reduction temperature of 1373 K, the biomass adding ratio of 0.9, the P_CO2/P_CO value of 1:1, and the reduction time of 15 to 25 min. Under this condition, the metallization rate and the residual carbon content of reduced samples are 75% to 80% and 0.69% to 0.11%, respectively. SEM-EDS and XRD examination of reduced samples obtained under the optimum condition shows that the major phases are metallic iron, calcium silicate and calcium phosphate, but phosphorus still remains in gangue. Subsequent melting separation experiments were conducted in a Si-Mo high-temperature furnace. Metal with the phosphorus content of some 0.4% was obtained from the reduced samples;and furthermore, metal with the phosphorus content of less than 0.3% could be obtained after introducing 2% to 4% Na₂CO₃ into the melting system. Based on the above analysis, the feasibility of applying biomass char for phosphorus removal is demonstrated.