Growth characteristics of metallic iron particles during direct reductive of ludwigite ore
LIANG Bin-jun1, YU Ce-en2, TANG Li-qun3, HU Hai-xiang1
1. Department of Construction Engineering, Gannan University of Science and Technology, Ganzhou 341000, Jiangxi, China; 2. College of Resources and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi, China; 3. Department of Safety Engineering, Guangxi Vactional College of Safety Engineering, Nanning 530100, Guangxi, China
Abstract:Ludwigite ore will be the main source of boron-containing raw materials in China, and the key of its processing and utilization lies in the B-Fe separation. The growth characteristics of metallic iron particles in the direct reduction process of ludwigite ore under different conditions were investigated, which could provide theoretical support for B-Fe separation and achieve the purpose of resource utilization of ludwigite ore. The microscopic images of metallic iron particles in the reduced pellets were obtained by Leica DMI5000M optical microscope, the sizes of metallic iron particles were analyzed and counted by the software of Image-pro Plus 6.0, and then the metallization rate of iron in the reduces product was tested by chemical analysis. Meawhile, the promoting mechanism of Na2CO3 for iron oxide reduction and the growth behavior of metallic iron particles were studied by SEM. The results showed that the iron oxides of ludwigite ore pellets could be effectively reduced in the presence of Na2CO3. The metallization rate of iron and the size of metallic iron particles increased effectively with the extension of reduction time. When the pellets were roasted at 1 100 ℃ for 60 min in the absence of Na2CO3, the metallization rate of iron and the size of metallic iron particles in the reduced products were 84.36% and 8.55 μm. However, the metallization rate of iron and the size of metallic iron particles could reach to 91.72% and 14.07 μm with the same roasting conditions in the presence of 15% Na2CO3. The results of SEM-EDS analysis showed that Na2CO3 not only promoted the metallic iron to separate from other substances, but also affected the migration behavior of metallic iron particles during the reduction roasting process. The metallic iron particles first changed from "point" contact to "neck" contact, and then re-intersected to form new grain boundaries and became polygonal particles during the direct reducing process. Finally, the polygon particles were connected to each other to form a densified aggregate.
梁斌珺, 余策恩, 唐丽群, 胡海祥. 硼铁矿直接还原过程中金属铁颗粒的生长特性[J]. 钢铁, 2022, 57(5): 31-39.
LIANG Bin-jun, YU Ce-en, TANG Li-qun, HU Hai-xiang. Growth characteristics of metallic iron particles during direct reductive of ludwigite ore[J]. Iron and Steel, 2022, 57(5): 31-39.
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