Research On Decomposition Of Tantalum-niobium Concentrate And Extraction Process Of Tantalum And Niobium In Sulfuric Acid System

Tantalum and niobium are rare high melting point metals,and their excellent properties of metals and alloys are widely used in high-tech fields such as steel,electronics,medicine and aerospace.The key to the extraction of tantalum niobium and its compounds lies in the decomposition of tantalum niobium ore and the separation of tantalum niobium.At present,the treatment method of tantalum-niobium ore widely used in industry is high-concentration hydrofluoric acid decomposition and extraction separation process,but this process will cause serious fluorine pollution and low resource utilization rate of refractory tantalum-niobium ore.For this reason,this paper focuses on the decomposition of tantalum-niobium ore by means of pressure strengthening conversion of tantalum-niobium in sulfuric acid system.The separation of tantalum and niobium can be realized under the following conditions,thereby greatly reducing fluorine pollution.In this paper,the Yichun tantalum-niobium concentrate is used as the experimental raw material to study the decomposition of tantalum-niobium in tantalum-niobium ore and the separation of tantalum-niobium.The main progress are as follows:The leaching of tantalum-niobium concentrate in sulfuric acid system was studied.The results show that the introduction of leaching aid ammonia fluoride in the autoclave without gas before leaching is very effective on the leaching of tantalum-niobium concentrate.On this basis,the pressure leaching conditions of tantalum-niobium concentrate were optimized.Under the optimal conditions,the leaching rates of tantalum and niobium were still not less than 93%and 96%,respectively.The mass concentration was reduced from 60-70%to 5.3%.The quantum chemical calculation results based on the DFT theory showed that after F^–was adsorbed on the surface of Mn Nb₂O₆（100）,there is a large area overlap between the s and p orbitals of F atoms and the s,p and d orbitals of surface Nb atoms,and the strong orbital hybridization of F atoms and surface Nb atoms strengthens the covalent effect between Nb-F.The leaching kinetics of niobium in the sulfuric acid system was studied.The leaching temperature has a very significant effect on the leaching of niobium in the sulfuric acid medium.The leaching process follows the surface reaction control kinetic model.The measured apparent activation energy is 43k J/mol,indicating that the leaching process At temperatures ranging from100°C to 200°C,the leaching process of niobium is controlled by chemical reactions.Taking the leaching solution of tantalum and niobium concentrates in the sulfuric acid system introduced with ammonia fluoride as the object,MIBK extraction method was used to separate tantalum and niobium.rate and separation factor of tantalum-niobium.The results showed that0.5mol/L of sulfuric acid was added to the leaching solution,the concentration of tantalum and niobium in the leaching solution was 38.19g/L,the extraction ratio was 3:1,and the extraction time was 5min.Under the experimental conditions,more than 98%of tantalum in the leaching solution was extracted in a single time,and the separation coefficient of tantalum and niobium was about5000,which effectively realized the separation of tantalum and niobium;3 mol/L of sulfuric acid was added to the residual tantalum extraction solution,and the extraction ratio was 3:1,The extraction time is 5 minutes,and the niobium in the tantalum residue is more than 99%in a single extraction.The extraction kinetics of tantalum and niobium in the leachate was studied.When the stirring speed was 400 rpm,the extraction of tantalum was controlled by the interfacial chemical reaction,and the extraction flux was F(kmol·s^-1·m^-2)=10^-2.34[Ta F₇^2-][H⁺][MIBK]_o.Apparent activation energy Ea=31.02 k J/mol;Activation entropyΔ^?H°=29.68 k J/mol,activation enthalpyΔ^?S°=-176.34J/（mol·K）.