Reaction Behavior of Phosphorus in Coal-Based Reduction of an Oolitic Hematite Ore and Pre-Dephosphorization of Reduced Iron

Abstract

Coal-based reduction followed by magnetic separation is an effective way to recover iron from high phosphorus-containing oolitic hematite ore. Given that high quantities of dephosphorization agent are needed to obtain low phosphorus reduced iron, a novel approach is proposed by the authors. Without prior phosphorus removal, the phosphorus was enriched in the reduced iron during a reduction process, then high-phosphorus reduced iron was refined to low phosphorus molten iron and high phosphorus dephosphorization slag to be used as a phosphate fertilizer. The influences of various parameters, including the reduction temperature, the reduction time, and the C/O molar ratio, on the reaction behavior of phosphorus during reduction process were studied. Experimental results indicate that a higher reduction temperature, a longer reduction time, or a higher C/O molar ratio was favorable for the reduction of apatite to phosphorus and the enrichment of phosphorus in reduced iron. X-ray diffraction (XRD) analysis demonstrated that the apatite was reduced to phosphorus and Ca 2 SiO 4 (or Ca(Al 2 Si 2 O 8 )) in the presence of SiO 2 and Al 2 O 3 , whilst the phosphorus enriched in reduced iron formed Fe 3 P. The migration behavior of phosphorus was investigated using line scanning analysis of reduction products at different reduction times. The results show that the phosphorus primarily existed in the slag phase 10 min before reduction, and a large amount of phosphorus migrated into iron phase from slag phase with a reduction time of 40 min. The phosphorus content in the iron phase only slightly changed after 50 min. The pre-dephosphorization of reduced iron was performed at 1873 K, indicating a higher basicity or Fe t O content of CaO-based slag was beneficial to dephosphorization of the reduced iron.

Characterization studies on Agbaja iron ore: a high-phosphorus content ore

“…As a consequence, a lot of research efforts have been focused on phosphorus removal from high-phosphorus iron ore [20,24,[32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] in a bid to reduce the P content to acceptable levels. Processes that had been employed for phosphorus removal from iron ores include thermal treatment [7,21,24,[38][39][40][41][49][50][51][52][53], microwave treatment [38,[54][55][56], ultrasonic treatment [54], acid leaching [12,17,20,49,[56][57][58][59][60], alkaline leaching [5,59], bioleaching [30,[61]…”

Effect of particle size on reduction kinetics of hematite ore in suspension roaster

“…The explored reserves of those iron ores reach 20 billion tons in China, which is characterized by complex mineral composition and ultra-fine grain size of iron minerals. It is difficult to enrich iron minerals of refractory iron ores using conventional fine grinding followed by forth flotation or magnetic separation effectively (Nunes et al, 2012;Gao et al, 2016;Zhu et al, 2019).…”

Effect of Roasting Temperature on Phase Transformation in Co-Reduction Roasting of Nickel Slag

“…Studies have illustrated that nickel slag and blast furnace dust as waste solid should be disposed of and reutilized urgently. At present, the technology of coal-based direct reduction roasting following magnetic separation has been demonstrated as an effective technology to process refractory iron ore [16][17][18][19][20]. In this study, a novel method called co-reduction roasting was proposed for the comprehensive utilization of nickel slag and blast furnace dust, considering that the nickel slag containing Fe and blast furnace dust containing Fe and C have complementary mineral and chemical components.…”