Experimental Study On Preparation Of Niobium-iron Alloy By Aluminothermic Reduction Of Niobium-bearing Iron Ore Powder

In order to find a new process for preparing niobium ferroalloy by simple and efficient treatment of low grade niobium iron ore,this paper aims at the problems of long process,high energy consumption and low niobium grade in the preparation of niobium ferroalloy because of the lack of rational utilization of niobium resources in China,For the comprehensive utilization and industrialization of Baotou Bayan Obo ore resources of niobium,a relatively efficient new approach was explored,and the preparation of niobium ferroalloy from Baotou BaiyunObo niobium-bearing iron ore powder was studied.The experimental scheme of gas-based selective reduction-slag gold melt fractionaluminothermic reduction is proposed.The feasibility of gas-based selective reduction reaction was analyzed by using HSC6.0 thermodynamic analysis software.Hydrogen was used as reducing gas in gas-based selective reduction phase,and the experimental temperature,reduction time and hydrogen flux were studied.The experimental temperature was 940℃,950℃,960℃,970℃,the reduction time was 2h,2.5h,3h,3.5h,the hydrogen flux was 60L/h,70L/h,80L/h,90L/h.The optimum conditions of hydrogen selective reduction are 950℃,3h,90L/h.Under these conditions,the weight loss rate can be calculated to be 22.32% through the experimental results,and the metallization rate is 95.23% and the reduction degree is 96.24%.Therefore,the best experimental condition of hydrogen reduction is that the experimental temperature is 950℃,the reduction time is 3 h,and the hydrogen flux 90L/h is the best experimental condition for hydrogen reduction.The melting separation experiment of niobium-bearing ore powder after reduction was carried out under this experimental condition.The experimental temperature was 1550℃ and the holding time was 25 min.After the reduced niobium-iron ore powder was melted at high temperature,the obtained Fe phase and slag phase were detected by ICP,sulfur and phosphorus.Iron and other impurity elements have been effectively removed,the desulphurization rate is about 99.5%,the dephosphorization rate is about 95%,the iron removal rate is 97%,niobium is enriched well in the slag,and the recovery rate of niobium is over 98%.The grade of niobium is about 2.1 times that of original ore.The aluminothermic reduction experiment of niobium-rich slag after separation of slag and gold was carried out.The reduction temperatures of 1500℃,1550℃ and 1600℃ were investigated,and the optimum temperature of 1550℃ was obtained.When the temperature is 1550℃,the holding time is 25 min and the basicity is 1.0,the niobium-rich slag can be obtained by aluminothermic reduction,in which the niobium is about 1.48 g and the yield of niobium is 78.8%.