The Basic Research On Coal-Based Direct Reduction For Low Grade And High Phosphorus Iron Ore

Along with the development of the steel industry, the demand of the rich mine and the Scrap steel are growing. Although China has abundant iron ore resources, but the rich is less,and the poor ore and symbiotic ore are much , difficult in using. At the same time, China lacks natural gas resources, and the coal resources is rich Therefore, the using of coal-based direct reduction technology is an important way to ravel out the lack of Scrap steel. However, the existing coal-based direct reduction process require high grade ore And low production efficiency, obstructing the technical development in the further. The paper is for studying on coal-based direct reduction process in utilizing the low-grade and hard-to-separate iron ores, and offering gists for this process developmentThe research obiect of this thesis is low-grade and high-kakoxene iron ore in YunNan province. The ores are divided into primaryore ore and oxidized ore. To research the physical and chemical properties of ore show that: ore has high phosphprus,high sulfur,high silicon and low-grade, and oxidized ore with Fe₂O₃ mainly ,then is limonite ,inaddition also has a little pyrite FeS₂. Gangue with SiO₂ main components is calcium silicon genus gangue mineral then is aluminum silicon gangue mineral. It is also found a little of non-ferrous metal. The beginning softening temperature of ore is very high, above 1250 degree centigrade, melting temperature is about 1400 degree centigrade.The roasting experimental of oxidized ore show that , the best system is:oxidized roasting temperature is 1020 degree centigrade, roasting time is 1.5 h,after roasting the ore grade improve to about 38.4%, desulfurization rate is about 89.47%, dephosphorization rate 19.01%, the result of SEM analysis show that : oxidation is comparison completely. Fe appeared aggregation phenomenon. The coal-based direct reduction experimental of oxidized ore show that, the best reduction system of roasting ore is:reduction temperature is 1100 degree centigrade, reduction time is two hours, deoxidize ore grade improve to about 45%, degree of metallization is above 85%, degree of reduction is also above 85%, integrated desulfurization rate is above 90%, integrated dephosphorization rate is above 30%. Microstructural observations by microscope and SEM show that Fe has obviously agglomeration phenomenon . and has a little of phosphorus always being in slag phase. slag phase has not any change. Laboratory studied on simplified process if or not that has not oxidized roasting, The results of thermal analysis of coal-based direct reduction showed that the activation energy of reduction are bigger, the reaction is not easily happened. The test result in laboratory indicate the result of coal-based direct induction is unstable that has not oxidized roasting, and the rate of desulfurization,dephosphorization is not tideal. The coal-based direct induction of low-grade and high phosphorus ore must oxidatly roasting oxygenation Roasting plays a vital role in the process of oxidation ore direct reduction...