Fundamental Study On Smelting Of Low Level Niobium-iron Alloy

Recently, with rapid development of iron and steel production in our nation, quantity demand of metallic niobium and niobium chemical compound are rapidly increasing for alloyed steel production and chemical industry etc. However, the output of metallic niobium and niobium-contained alloyed steel and niobium-bearing chemical compound can't satisfy the demand of national economic development. Furthe more, present niobium enriching and smelting methods have some deficiencies, for example, long process flow, high energy consumption, high cost, insufficient resource utilization, which limit the development of niobite smelting in some extent.Therefore, this paper studies the fundamental theory for smelting Niobite based on the Fe-Nb-RE special resource from Baotou Steel and a new technology is developed to enrich niobium into slag by selective reduction with tank reduction method.. The charging methods of tank reduction include column stuff, pancake stuff and CCB. The optimal reduction technology and operation parameters are obtained by comparing the results of reducing iron preparation concentrate and niobite tailing with different tank reduction methods.The main contents and results of this paper are:(1)Columnar tank reduction experiments:The metallization ratio nearly approachs the highest value after 4h reducing for both iron preparation concentrate and niobite tailing at 850℃and 950℃, and the metallization ratio does not change greatly with time increasing after 4h. For examples, the metallization of niobite tailing is 55% at 850℃and 73% at 950℃eventually, while the metallization of iron preparation concentrate is 90% at 950℃.(2) Pancake tank reduction experements:The reducing rate of niobite tailing is faster at earlier stage of 950℃, such as the metallization ratio is 77% after 2 hours, which, is 16% higher than the metallization ratio of iron preparation concentrate. But after 2 hours, the metallization ratio of niobite tailing increases slowly and reachs 84% after eight hours. The metallization ratio of iron preparation concentrate reachs the maximum (about 90%) after 4 hours reducing And the metallization ratio does not change Greatly with time increasing. Therefore, the metallization ratio of niobium preparation concentrate will higher than niobite tailing in practical production.(3) Carbon Composite iron ore hot Briquette tank reduction experiments: Reducing temperature is most important parameter to the metallization ratio of Carbon Composite iron ore hot Briquette, comparing with reducing time and coal proportion. When Coal proportion is 10% and 20% respective, the metallization ratio of Carbon Composite iron ore hot Briquette is 70～74% at 850℃and 84～88% at 950℃correspoding, the later value is 14% higher than the former.(4) Analysis and comparation on different charging methods:The metallization ratio increases with reducing time increase for any charging methods,In this experiment, when the reducing time increases from 2 hours to 4 hours, the metallization ratio increases 7-8% generally. At the same reducing condition, the metallization ratios of Carbon Composite iron ore hot Briquette (Coal proportion10% or 20%) and Pancake tank reduction are similar, while obvious higher than that of columnar tank reduction.(5) Analysis and comparation on reduction of iron preparation concentrate and niobite tailing:The metallization ratio of iron preparation concentrate with columnar and pancake tank reduction method is obviouser high than that of niobite tailing. The former can reach 90%, while the latter is merely 72-84%. For niobite tailing, the metallization ratio with pancake tank reduction is obvious higher than that with columnar tank reduction (about higher 10%). But the metallization ratios of iron preparation concentrate with two different charging method are similar to each other. Therefore, for niobite preparation concentrate in the next work, the proper charging method should be redetermined through experiment and mechanism analysis.In summary, the optimal technology parameters for niobite tailing reduction are:the charging method is pancake and reducing time is 2 hours.at 950℃This results of this paper provide theory basis for niobium-iron ore smelting in Baotou Steel and references for the determination of technological parameters.