Abstract: As rare precious metals, niobium and tantalum are widely used in the fields of high-precision instruments and military equipment due to their excellent physical and stable chemical properties. China is rich in niobium and tantalum resources, most of which are associated deposits that coexist with various metal minerals and have high comprehensive utilization value. In response to the separation and recovery of uranium, thorium, and rare earth resources in niobium and tantalum concentrates, the HF-H2SO4 mixed acid method is used to preferentially extract niobium and tantalum, while enriching uranium, thorium, and rare earth in the slag. In this research, the one-factor experimental design is applied to study the leaching behavior of niobium and tantalum, meanwhile, the process mechanism and kinetics are discussed. The results show that using high concentration hydrofluoric acid, increasing the amount of hydrofluoric acid and sulfuric acid is beneficial for the leaching rate of niobium and tantalum. Reducing the ore particle size, increasing temperature, and extending leaching time all has favorable effect on the leaching rate of niobium and tantalum. The optimal leaching conditions obtained are as follows: 40wt% HF 1120 g/kg, H2SO4 392 g/kg, average particle size -25 μm (75%), leaching temperature 80℃, and leaching time 4 h. In which the leaching rate of niobium is greater than 98%, and that of tantalum is greater than 97%. Uranium, thorium, and rare earth are retained in the slag, and the enrichment rate in the slag reaches 3.0 to 4.2. The kinetic research has shown that the leaching process of tantalum and niobium conforms to the shrinkage core model and belongs to the chemistry and diffusion mixed control. The apparent activation energy of Nb obtained from the experiment is 34.00 kJ/mol, and that of Ta is 36.26 kJ/mol. This method effectively extracted niobium-tantalum and enriched the other valuable elements, which build the foundation for the design of the separation and purification process.

Key words: Niobium-tantalum concentrate, mixed acid leaching, radionuclide, rare earth, leaching kinetics

摘要： 铌、钽作为稀有贵金属，因其优良的物理性质和稳定的化学性质，在高精尖器械及军事装备领域被广泛应用。我国铌钽资源丰富，多为共伴生矿床，与多种金属矿物共存，具有较高的综合利用价值。针对铌钽精矿中铀、钍及稀土资源分离及回收问题，采用HF-H2SO4混酸法优先提取铌、钽，同时将铀、钍及稀土富集于渣中。本研究应用单因素试验法研究了铌、钽的浸出规律，并讨论了过程机理及其动力学。结果表明，使用高浓度HF，提高HF、H2SO4用量有利于铌、钽的浸出，减小矿石粒径、提高温度和延长浸出时间均能提高铌、钽浸出率。获得的最优浸出参数如下：HF浓度40wt%、HF用量1120 g/kg、H2SO4用量392 g/kg、平均粒径-25 μm (75%)、浸出温度80℃、浸出时间4 h。此条件下铌浸出率大于98%，钽浸出率大于97%，铀、钍及稀土保留在渣中，渣中富集率达3.0~4.2。动力学研究表明，铌、钽的浸出过程符合收缩核模型，并属于混合控制类型，铌、钽的表观活化能分别为34.00和36.26 kJ/mol。该方法有效提取了铌、钽并对其余有价元素进行富集，为后续分离提纯工艺的设计奠定基础。

关键词: 铌钽精矿, 混酸浸出, 放射性核素, 稀土, 浸出动力学