【摘要】 为了综合利用白云鄂博尾矿中的铌、铁资源，将微波冶金技术与直接还原技术耦合，进行白云鄂博尾矿低温碳热还原试验，研究微波场中铌和铁的选择性还原行为，优化工艺参数。结果表明：微波能够降低白云鄂博尾矿碳热还原的温度，加快金属化速度，并且随着温度的升高、保温时间的延长、升温速率的加快，铁的金属化率增加。铌矿物的还原行为与矿物中含铁量和嵌布关系有关。在富含CaO和CaF₂的区域，铌酸铁发生FeNb₂O₆→Nb₂O₅→CaNb₂O₆→Ca₂Nb₂O₆F的矿相转变；铌酸钙发生CaNb₂O₆→Ca₂Nb₂O₇→Ca₂Nb₂O₆F的矿相转变。当矿物中全铁含量(T_Fe)=10.60%，温度小于1100℃时，铌矿物中的铌不能被C还原，主要以Ca₂Nb₂O₆F的形式分布在渣相中；当T_Fe=29.20%，铌矿物中的铌在1000℃时开始被C还原成NbO₂和NbC，并与Fe,FeS紧密粘连。微波场中铌、铁选择性还原的条件是还原温度900℃，保温时间40 min，升温速率30℃·min^-1时，铁的金属化率达到93.07%，铌矿物中的铌未被还原，实现了铌、铁的选择性还原。更多还原

【Abstract】 The reserves of niobium resources in Bayan Obo are abundant,but the niobium minerals in it have the characteristics of"multiple species,low grade,fine particle size and complex embedded relationships",as a result,in the traditional beneficiation process based on"iron and rare earth",niobium resources are scattered in all levels of beneficiation processes,and finally accumulated in tailings dams,with zero utilization rate.China is rich in non-coking coal resources,and the direct reduction technology does not depend on coke,eliminating the need for cooking equipment,and can also obtain high-grade iron concentrates.It is in line with Chinese resource utilization direction,and it is an effective method to deal with complex co-existing ores.However,the high reduction temperature required by the direct reduction technology limits the selective reduction of valuable elements in the ore.Carbon can effectively absorb microwaves.In the process of carbothermic direct reduction,microwaves are selected for heating,which can take advantage of the characteristics of bulk heating and selective heating of microwave heating to achieve rapid temperature rise.The coupling of microwave metallurgy technology and direct reduction technology can reduce the reaction temperature of direct reduction,speed up the reaction speed,and enhance the reduction ability.Based on this,this work proposed a new technology of"superconducting niobium separationmicrowave iron removal-electrolytic niobium extraction"to deal with Bayan Obo tailings resources.Through the"permanent magnetelectromagnetic-superconducting"cascade magnetic separation technology and step-by-step flotation technology,the niobium was enriched in the form of niobium-rich ore.Under the action of external field strengthening,the selective reduction of niobium-rich ore was carried out to remove iron to further realize the enrichment of niobium in niobium-rich ore.Finally,the selective reduction characteristics of electrochemical metallurgy were used to extract niobium in the form of ferroniobium alloy.In this paper,the low-temperature carbothermic reduction experiment of Bayan Obo tailings was carried out in the microwave field,optimize process parameters,achieve selective reduction of niobium and iron.The results showed that microwave could reduce the temperature of carbothermic reduction of Bayan Obo tailings and speed up the metallization rate.And with the increase of temperature,the prolongation of holding time and the acceleration of heating rate,the metallization rate of tailings increased.The reduction behavior of niobium minerals was related to the content and intercalation in the minerals.In the region rich in CaO and CaF₂,iron niobate underwent the mineral phase transformation of FeNb₂O₆→Nb₂O₅→CaNb₂O₆→Ca₂Nb₂O₆F;calcium niobate underwent the mineral phase transformation of CaNb₂O₆→Ca₂Nb₂O₇→Ca₂Nb₂O₆F.When total iron content of minerals (T_Fe)=10.60%and the temperature was less than 1100℃，niobium minerals could not be reduced by C,and were mainly distributed in the slag phase in the form of Ca₂Nb₂O₆F;When T_Fe=29.20%,niobium minerals were reduced to NbO₂ and NbC by C at 1000℃，and were closely adhered to Fe and FeS.The conditions for selective reduction of niobium and iron in microwave field were reduction temperature of 900℃，holding time of 40 min,heating rate of 30℃·min^-1,the metallization rate of niobium tailings in Bayan Obo was 93.07%,and niobium minerals were not reduced,which could achieve selective reduction of iron and niobium.更多还原