Method for extracting tantalum and niobium by roasting and melting tantalum and niobium concentrate through villiaumite after multiple times of acid leaching

Abstract

The invention discloses a method for extracting tantalum and niobium by roasting and melting tantalum and niobium concentrate through villiaumite after multiple times of acid leaching, which comprises the following steps: fully grinding the tantalum and niobium concentrate through a grinding machine, sieving, and fully mixing with concentrated acid according to a certain mass ratio for first acid leaching; filtering the mixed solution, and washing with pure water; mixing the filter residues with concentrated acid according to a certain mass ratio, carrying out secondary acid leaching, filtering, and washing the filter residues with pure water; drying the filter residue, and fully mixing with villiaumite according to a certain mass ratio; fully grinding the mixed solid roasting material by using a grinding machine; roasting and melting the materials; and leaching the roasted material with water or dilute acid, filtering after leaching is completed, and collecting filtrate. According to the method, most impurity ions can be effectively removed through secondary acid leaching impurity removal in the leaching process. And the fluorine salt roasting cost is low, the tantalum-niobium leaching effect is good, the tantalum-niobium leaching rate can reach 90% or above, and the comprehensive utilization rate of resources is high.

Description

Technical Field

[0001] The invention relates to a method for extracting tantalum and niobium from molten tantalum and niobium concentrate by fluoride salt roasting after multiple acid leaching. Background Art

[0002] Tantalum (Ta) and niobium (Nb) are two refractory metals that possess inherent properties such as corrosion resistance, superconductivity, high electrical capacitance, and biocompatibility. The two metals often occur together in various minerals and are combined with other oxide impurities. The two metals are also similar in chemical and physical properties, which makes their separation and purification difficult.

[0003] Currently, these metals are usually recovered from ores by pyrometallurgy or hydrometallurgy. Pyrometallurgy is carried out by aluminothermic reduction or carbothermic reduction; hydrometallurgy includes tantalum and niobium leaching, leachate purification and impurity removal, precipitation, calcination and final refining of high-purity metal oxides. However, since hydrometallurgical leaching operations usually use a mixture of HF and H2SO4, both of which are highly corrosive acids and present certain dangers, they bring operational challenges when producing Ta and Nb on an industrial scale.

[0004] Although this method has significant effects in the extraction of tantalum and niobium, it also brings some environmental problems. For example, hydrofluoric acid is highly volatile. When acid-hydrolyzing tantalum and niobium ore, about 10% of the hydrofluoric acid will evaporate into the air in the form of fluorine-containing waste gas, causing pollution. The generated fluorine-containing waste slag also needs to be properly handled. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for extracting tantalum and niobium from molten tantalum and niobium concentrate by fluoride salt roasting after multiple acid leaching, aiming to solve the above technical problems.

[0006] To achieve the above purpose, the present invention proposes a method for extracting tantalum and niobium from molten tantalum and niobium concentrate by multiple acid leaching followed by fluoride salt roasting, comprising:

[0007] S1. Grind the tantalum-niobium concentrate by a grinder, sieve it, and mix it with concentrated acid in a certain mass ratio for the first acid leaching;

[0008] S2, filtering the mixed solution in step S1, and washing with pure water to remove impurities in the tantalum-niobium concentrate;

[0009] S3, mixing the filter residue after filtering in step S2 with concentrated acid in a certain mass ratio for a second acid leaching and filtering, and washing the filter residue with pure water;

[0010] S4, drying the filter residue in step S3 and mixing it with the fluoride salt in a certain mass ratio;

[0011] S5, grinding the solid roasted material mixed in step S4 by a grinder;

[0012] S6, roasting and melting the material in step S5 under certain conditions;

[0013] S7, leaching the material after roasting in step S6 with water or dilute acid, filtering after leaching, and collecting the filtrate.

[0014] In one embodiment, the steps of grinding the tantalum-niobium concentrate by a grinder, sieving the tantalum-niobium concentrate, and mixing the tantalum-niobium concentrate with concentrated acid in a certain mass ratio for the first acid leaching are specifically as follows:

[0015] The tantalum-niobium concentrate is fully ground by a grinder and sieved through 200 mesh to a particle size less than 200 mesh, and is fully mixed with concentrated acid in a mass ratio of 1:(0.2-1.5) for the first acid leaching. The acid leaching time is 0.5h and the reaction temperature is 80°C.

[0016] In one embodiment, the concentrated acid in step S1 includes one or more of concentrated sulfuric acid, concentrated hydrochloric acid, and concentrated nitric acid.

[0017] In one embodiment, the filter residue after filtering in step S2 is mixed with concentrated acid in a certain mass ratio for a second acid leaching and filtering, and the filter residue is washed with pure water in the following steps:

[0018] The filter residue after filtering in step S2 is mixed with concentrated acid in a mass ratio of 1:(0.2-1.5) for a second acid leaching, the acid leaching time is 0.5h, the reaction temperature is 80°C, filtered, and the filter residue is washed with pure water.

[0019] In one embodiment, the step of drying the filter residue in step S3 and mixing it with the fluoride salt in a certain mass ratio is specifically as follows:

[0020] After drying the filter residue in step S3, the filter residue is fully mixed with the fluoride salt in a mass ratio of 1:(0.5-2).

[0021] In one embodiment, the fluoride salt includes ammonium bifluoride or ammonium fluoride.

[0022] In one embodiment, the step of roasting and melting the material in step S5 under a certain environment is specifically as follows:

[0023] The material in step S5 is roasted and melted, the roasting temperature is 200° C.-400° C., and the roasting and heat preservation time is 1 h-2 h.

[0024] In one embodiment, the acid solution used in step S7 is one of sulfuric acid or hydrochloric acid and has a hydrogen ion concentration lower than that of the concentrated acid in step S1.

[0025] In the technical solution of the present invention, the method for extracting tantalum and niobium from molten tantalum and niobium concentrate by fluoride salt roasting after multiple acid leaching comprises:

[0026] S1. Grind the tantalum-niobium concentrate by a grinder, sieve it, and mix it with concentrated acid in a certain mass ratio for the first acid leaching;

[0027] S2, filtering the mixed solution in step S1, and washing with pure water to remove impurities in the tantalum-niobium concentrate;

[0028] S3, mixing the filter residue after filtering in step S2 with concentrated acid in a certain mass ratio for a second acid leaching and filtering, and washing the filter residue with pure water;

[0029] S4, drying the filter residue in step S3 and mixing it with the fluoride salt in a certain mass ratio;

[0030] S5, grinding the solid roasted material mixed in step S4 by a grinder;

[0031] S6, roasting and melting the material in step S5 under certain conditions;

[0032] S7, leaching the material after roasting in step S6 with water or dilute acid, filtering after leaching, and collecting the filtrate.

[0033] The present invention uses lithium precipitation mother liquor as a raw material, and directly mixes it with an extractant for extraction without adjusting the alkali, thereby avoiding the need to supplement sodium salt or potassium salt to supplement alkalinity in the traditional lithium extraction process, and reducing the increase of metal ions in the water sample; at the same time, there is no need to carry out a concentration step for the lithium precipitation mother liquor, thereby reducing energy consumption and production costs, and at the same time, the lithium extraction rate and direct recovery rate are high.

[0034] The lithium carbonate prepared by the present invention has high purity, especially reducing the proportion of potassium and sodium salts in the lithium carbonate product, reaching the standard of battery-grade lithium carbonate, and solving the problems of complex purification process and high production cost of industrial-grade lithium carbonate prepared by traditional concentrated lithium precipitation.

[0035] The present invention uses concentrated sulfuric acid to remove impurities and filter, fluoride salt to roast at high temperature, and water to leach tantalum and niobium. In the leaching process, secondary acid leaching can effectively remove most of the impurity ions. In addition, the use of hydrofluoric acid is avoided from the source, the fluoride salt roasting cost is low, the tantalum and niobium leaching effect is good, the tantalum and niobium leaching rate can reach more than 90%, and the comprehensive utilization rate of resources is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0037] Figure 1 This is a process flow chart of a method for extracting tantalum and niobium from molten tantalum and niobium concentrate by fluoride salt roasting after multiple acid leaching according to an embodiment of the present invention.

[0038] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0041] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0042] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0043] The invention provides a method for extracting tantalum and niobium from molten tantalum and niobium concentrate by fluoride salt roasting after multiple acid leaching.

[0044] like Figure 1As shown, the method for extracting tantalum and niobium from molten tantalum and niobium concentrate by fluoride salt roasting after multiple acid leaching provided by the embodiment of the present invention comprises:

[0045] (1) The tantalum-niobium concentrate is fully ground by a grinder and then sieved to 200 mesh. The particle size is less than 200 mesh so that the acid leaching reaction can fully react. The concentrate is fully mixed with concentrated acid at a mass ratio of 1:(0.2-1.5) for the first acid leaching. The acid leaching time is 0.5h and the reaction temperature is 80°C. The concentrated acid includes one or more of concentrated sulfuric acid, concentrated hydrochloric acid and concentrated nitric acid.

[0046] (2) Filter the mixed solution in step 1 and wash it with pure water for several times to remove most of the impurities such as iron and manganese in the tantalum-niobium concentrate. The removal rate of the iron and manganese impurities in the tantalum-niobium concentrate is greater than 70%.

[0047] (3) The filter residue after filtering in step 2 is mixed with concentrated acid in a mass ratio of 1: (0.2-1.5) for a second acid leaching, the acid leaching time is 0.5h, the reaction temperature is 80°C, and the filter residue is filtered and washed with pure water for several times to remove most of the iron, manganese and other impurities remaining after the first acid leaching. After two acid leachings, the removal rate of iron and manganese impurities in the tantalum-niobium concentrate is greater than 95%.

[0048] (4) After drying the filter residue in step 3, the filter residue is fully mixed with a fluoride salt in a mass ratio of 1:(0.5-2). The fluoride salt includes one or both of ammonium bifluoride and ammonium fluoride.

[0049] (5) The solid roasted material mixed with the fluoride salt in step 4 is fully ground by a grinder and then sieved to 200 mesh. The particle size is less than 200 mesh so that the roasting process can fully react and the tantalum and niobium leaching rate is high. If the particle size is larger than 200 mesh, the reaction time and cost will be increased.

[0050] (6) The material in step 5 is roasted and melted at a temperature of 200°C-400°C and a roasting holding time of 1h-2h. After roasting, the tantalum oxide and niobium oxide in the tantalum-niobium concentrate are melted with ammonium bifluoride to produce a calcined product composed of (NH4)2TaF7 and (NH4)3NbOF6. The specific reaction is as follows:

[0051] Ta2O5+NH4HF2→(NH4)2TaF7

[0052] Nb2O5+NH4HF2→(NH4)3NbOF6

[0053] (7) Leaching the material after roasting in step 6 with water or dilute acid, wherein the seed acid is one or both of sulfuric acid and hydrochloric acid, the leaching temperature is 60-80°C, the leaching time is 0.5-1h, and after the leaching is completed, filtering is performed to collect H2TaF7 and H3NbOF6 solutions.

[0054] The present application is explained below through various specific embodiments.

[0055] Example 1

[0056] This example uses a tantalum-niobium concentrate as raw material, and its main components are as follows:

[0057]

[0058] Table 1

[0059] 80g of raw material was fully ground by a grinder and then sieved to 200 mesh. After sieving, a certain proportion of 98% sulfuric acid was added according to a mass ratio of 1: (0.2-1.5) and heated on a magnetic stirrer for reaction for 0.5h. The reaction temperature was 80°C and the stirring speed was 100-300rpm / min. After the reaction was completed, the first acid leaching liquid and acid leaching residue were obtained by filtration, and the filter residue was washed several times with pure water. Then the acid leaching residue was dried, and a certain proportion of 98% sulfuric acid was continued to be added according to a mass ratio of 1: (0.2-1.5) to react on a magnetic stirrer. The reaction conditions were the same as the first acid leaching. After the reaction was completed, the second acid leaching liquid and acid leaching residue were obtained by filtration. After the two acid leachings, the total removal rate of iron and manganese reached 96.66%. After drying the filter residue, it is fully mixed with ammonium bifluoride in a certain proportion and fully ground to 200 meshes by a grinder. Then, the obtained mixture is placed in a muffle furnace for roasting at a temperature of 200°C for a time of 2 hours. After roasting, tantalum oxide, niobium oxide and ammonium bifluoride in the tantalum-niobium concentrate are melted to produce a calcined product composed of (NH4)2TaF7 and (NH4)3NbOF6. Then, the obtained calcined product is leached with water at a leaching temperature of 60-80°C for a leaching time of 0.5 hours. Finally, H2TaF7 and H3NbOF6 solutions are collected. The leaching rate of tantalum can reach 91.52%, and the leaching rate of niobium can reach 93.67%.

[0060] Example 2

[0061] The raw materials used in this embodiment are the same as the tantalum-niobium concentrate in Example 1, except that the roasting temperature is different. 80g of the raw materials are ground and sieved to 200 meshes in a grinder. After sieving, a certain proportion of 98% sulfuric acid is added according to a mass ratio of 1: (0.2-1.5) and heated on a magnetic stirrer for reaction for 0.5h. The reaction temperature is 80°C and the stirring speed is 100-300rpm / min. After the reaction is completed, the first acid leaching liquid and acid leaching residue are obtained by filtration, and the filter residue is washed several times with pure water. Then the acid leaching residue is dried, and a certain proportion of 98% sulfuric acid is added according to a mass ratio of 1: (0.2-1.5) to react on a magnetic stirrer. The reaction conditions are the same as the first acid leaching. After the reaction is completed, the second acid leaching liquid and acid leaching residue are obtained by filtration. The total removal rate of iron and manganese after two acid leachings reaches 96.98%. After drying the filter residue, it is fully mixed with ammonium bifluoride in a certain proportion and fully ground to 200 meshes by a grinder. Then, the obtained mixture is placed in a muffle furnace for roasting at a temperature of 300°C for a time of 2 hours. After roasting, tantalum oxide, niobium oxide and ammonium bifluoride in the tantalum-niobium concentrate are melted to produce a calcined product composed of (NH4)2TaF7 and (NH4)3NbOF6. Then, the obtained calcined product is leached with water at a leaching temperature of 60-80°C for a leaching time of 0.5 hours. Finally, H2TaF7 and H3NbOF6 solutions are collected. The leaching rate of tantalum can reach 93.34%, and the leaching rate of niobium can reach 94.48%.

[0062]

[0063] Table 2

[0064] Example 3

[0065] The raw materials used in this embodiment are the same as the tantalum-niobium concentrate in Example 1, except that the roasting temperature is different. 80g of the raw materials are ground and sieved to 200 meshes in a grinder. After sieving, a certain proportion of 98% sulfuric acid is added according to a mass ratio of 1: (0.2-1.5) and heated on a magnetic stirrer for reaction for 0.5h. The reaction temperature is 80°C and the stirring speed is 100-300rpm / min. After the reaction is completed, the first acid leaching liquid and acid leaching residue are obtained by filtration, and the filter residue is washed several times with pure water. Then the acid leaching residue is dried, and a certain proportion of 98% sulfuric acid is added according to a mass ratio of 1: (0.2-1.5) to react on a magnetic stirrer. The reaction conditions are the same as the first acid leaching. After the reaction is completed, the second acid leaching liquid and acid leaching residue are obtained by filtration. The total removal rate of iron and manganese after two acid leachings reaches 97.11%. After drying the filter residue, it is fully mixed with ammonium bifluoride in a certain proportion and fully ground to 200 meshes by a grinder. Then the obtained mixture is placed in a muffle furnace for roasting at a temperature of 400°C for a time of 2 hours. After roasting, tantalum oxide, niobium oxide and ammonium bifluoride in the tantalum-niobium concentrate are melted to produce a calcined product composed of (NH4)2TaF7 and (NH4)3NbOF6. Then the obtained calcined product is leached with water at a leaching temperature of 60-80°C for a leaching time of 0.5 hours. Finally, H2TaF7 and H3NbOF6 solutions are collected. The leaching rate of tantalum can reach 90.19%, and the leaching rate of niobium can reach 92.76%.

[0066]

[0067] Table 3

[0068] In summary, the present invention uses concentrated sulfuric acid to remove impurities and filter, fluoride salt high temperature roasting, and water leaching to extract tantalum and niobium. In the leaching process, secondary acid leaching can effectively remove most of the impurity ions. In addition, the use of hydrofluoric acid is avoided from the source, and the cost of fluoride salt roasting is low. The tantalum and niobium leaching effect is good, the tantalum and niobium leaching rate can reach more than 90%, and the comprehensive utilization rate of resources is high.

[0069] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for extracting tantalum and niobium from molten tantalum and niobium concentrate by multiple acid leaching followed by fluoride salt roasting, characterized in that: The method for extracting tantalum and niobium from molten tantalum and niobium concentrate by fluoride salt roasting after multiple acid leaching comprises: S1. Grind the tantalum-niobium concentrate by a grinder, sieve it, and mix it with concentrated acid in a certain mass ratio for the first acid leaching; S2, filtering the mixed solution in step S1, and washing with pure water to remove impurities in the tantalum-niobium concentrate; S3, mixing the filter residue after filtering in step S2 with concentrated acid in a certain mass ratio for a second acid leaching and filtering, and washing the filter residue with pure water; S4, drying the filter residue in step S3 and mixing it with the fluoride salt in a certain mass ratio; S5, grinding the solid roasted material mixed in step S4 by a grinder; S6, roasting and melting the material in step S5 under certain conditions; S7, leaching the material after roasting in step S6 with water or dilute acid, filtering after leaching, and collecting the filtrate.

2. The method for extracting tantalum and niobium from molten tantalum and niobium concentrate by multiple acid leaching followed by fluoride salt roasting according to claim 1, characterized in that: The steps of grinding the tantalum-niobium concentrate by a grinder, sieving it, and mixing it with concentrated acid in a certain mass ratio for the first acid leaching are specifically as follows: The tantalum-niobium concentrate is fully ground by a grinder and sieved through 200 mesh to a particle size less than 200 mesh, and is fully mixed with concentrated acid in a mass ratio of 1:(0.2-1.5) for the first acid leaching. The acid leaching time is 0.5h and the reaction temperature is 80°C.

3. The method for extracting tantalum and niobium from molten tantalum and niobium concentrate by fluoride salt roasting after multiple acid leaching according to claim 2, characterized in that: The concentrated acid in step S1 includes one or more of concentrated sulfuric acid, concentrated hydrochloric acid, and concentrated nitric acid.

4. The method for extracting tantalum and niobium from molten tantalum and niobium concentrate by fluoride salt roasting after multiple acid leaching according to claim 1, characterized in that: The steps of mixing the filter residue after filtering in step S2 with concentrated acid in a certain mass ratio for a second acid leaching and filtering, and washing the filter residue with pure water are specifically as follows: The filter residue after filtering in step S2 is mixed with concentrated acid in a mass ratio of 1:(0.2-1.5) for a second acid leaching, the acid leaching time is 0.5h, the reaction temperature is 80°C, filtered, and the filter residue is washed with pure water.

5. The method for extracting tantalum and niobium from molten tantalum and niobium concentrate by fluoride salt roasting after multiple acid leaching according to claim 1, characterized in that: The step of drying the filter residue in step S3 and fully mixing it with the fluoride salt in a certain mass ratio is specifically as follows: After drying the filter residue in step S3, the filter residue is fully mixed with the fluoride salt in a mass ratio of 1:(0.5-2).

6. The method for extracting tantalum and niobium from molten tantalum and niobium concentrate by fluoride salt roasting after multiple acid leaching according to claim 5, characterized in that: The fluoride salt includes ammonium bifluoride or ammonium fluoride.

7. The method for extracting tantalum and niobium from molten tantalum and niobium concentrate by fluoride salt roasting after multiple acid leaching according to claim 1, characterized in that: The step of roasting and melting the material in step S5 under a certain environment is specifically as follows: The material in step S5 is roasted and melted, the roasting temperature is 200° C.-400° C., and the roasting and heat preservation time is 1 h-2 h.

8. The method for extracting tantalum and niobium from molten tantalum and niobium concentrate by fluoride salt roasting after multiple acid leaching according to claim 1, characterized in that: The acid solution used in step S7 is one of sulfuric acid or hydrochloric acid and has a hydrogen ion concentration lower than the concentrated acid in step S1.

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