KR102376746B1 - A method for manufacuring tantalum powder using metallothermic reduction - Google Patents

Abstract

Provided is a method for smelting tantalum using a metal thermal reduction method capable of smelting high-purity tantalum with excellent yield by minimizing unreacted raw materials by incrementally adding a reducing agent.
The method for smelting tantalum using the metal thermal reduction method according to the present invention comprises the steps of charging and heating a raw material and a diluent containing tantalum in a reaction vessel, incrementally introducing a reducing agent into the reaction vessel, and the reducing agent and the raw material and reacting the material to produce tantalum.

Description

Smelting method of tantalum using metal thermal reduction method

The present invention relates to a smelting method of tantalum using a metal thermal reduction method capable of smelting high-purity tantalum with excellent yield by minimizing unreacted raw materials.

Tantalum has excellent corrosion resistance, strength, dielectric constant, and workability (ductility), so it is widely used in industries such as electrical and electronic, aviation, medical, optics, and military. It is used as a material for superalloys for aircraft engines and gas turbines for power generation.

The manufacturing technology of tantalum metal powder includes a method of reducing Ta ₂ O ₅ with carbon, a method of reducing with Ca and Mg, a method of reducing TaCl ₅ with hydrogen, a method of reducing TaCl ₅ with a reducing metal such as Mg and Na, K ₂ TaF There is the molten salt electrolysis method of ₇ . In the case of the carbon reduction method, a high temperature of 1500 ℃ is required and the concentration of residual oxygen is high. The method of reducing TaCl ₅ to hydrogen is known to have a serious corrosion problem due to HCl by-products, and has a disadvantage in that it is difficult to control the particle size. In addition, the molten salt electrolysis method of K ₂ TaF ₇ has a problem in that a dendritic powder is obtained and there is a limitation in its utilization.

Therefore, tantalum metal powder is mostly produced by the Hunter process, but there is a problem of low yield due to high process temperature and high wastewater treatment to remove by-products. The existing tantalum powder manufacturing method is manufactured by a batch type process in which raw materials, reducing agents, and diluents are mixed and charged at the same time to react. However, when the reaction starts, there is a problem in that unreacted raw materials are generated because the reaction proceeds as an explosive reaction.

In addition, it is difficult to control the reaction temperature and speed, so there are many by-products generated after the reaction, and a large amount of wastewater is generated to remove them, which causes environmental load problems and wastewater treatment cost problems. Accordingly, there is an urgent need for the development of a tantalum smelting method with excellent yield and high purity through a stable process.

1. Korean Patent Publication No. 10-0438670 2. Korean Patent Publication No. 10-2001-0099260

An object of the present invention is to provide a method for smelting tantalum using a metal thermal reduction method capable of smelting high-purity tantalum with excellent yield by minimizing unreacted raw materials by incrementally adding a reducing agent.

However, these tasks are exemplary, and the technical spirit of the present invention is not limited thereto.

A method for smelting tantalum using a metal thermal reduction method according to the technical idea of the present invention for achieving the above technical problem includes the steps of charging and heating a raw material and a diluent containing tantalum in a reaction vessel, and incrementally adding a reducing agent into the reaction vessel It characterized in that it comprises the step of adding and the reducing agent and the raw material react to produce tantalum.

In some embodiments of the present invention, the raw material may be K ₂ TaF ₇ .

In some embodiments of the present invention, the diluent may be at least one selected from NaCl, KCl, LiCl, and KF.

In some embodiments of the present invention, the diluent may be added in an amount of more than 6.2 mol and less than 6.7 mol per 1 mol of the raw material.

In some embodiments of the present invention, the reducing agent may be at least one selected from Ca, Na, and Mg.

In some embodiments of the present invention, 5 to 7 mol of the reducing agent may be added per 1 mol of the raw material.

In some embodiments of the present invention, the reducing agent may be introduced into the reaction vessel in increments of 5 times at intervals of 5 minutes.

In some embodiments of the present invention, the generating of tantalum may be performed at 950° C. or less.

In some embodiments of the present invention, the purity of the smelted tantalum may be 99.95% by weight or more.

In some embodiments of the present invention, the oxygen content of the smelted tantalum may be 988 ppm or less.

In some embodiments of the present invention, the final yield of the smelted tantalum may be 83% or more.

The method for smelting tantalum using the metal thermal reduction method according to the present invention can smelt high-purity tantalum with excellent yield by minimizing unreacted raw materials by incrementally adding a reducing agent.

In addition, the method for smelting tantalum using the metal thermal reduction method according to the present invention can reduce environmental load and reduce wastewater treatment costs by reducing process by-products generated in a stable process with controlled reaction temperature and speed.

In addition, tantalum using the metal thermal reduction method according to the present invention may have a purity of 99.95% by weight or more, an oxygen content of 988ppm or less, and a yield of 83% or more.

The above-described effects of the present invention have been described by way of example, and the scope of the present invention is not limited by these effects.

1 is a flowchart schematically illustrating a method for smelting tantalum using a metal thermal reduction method according to an embodiment of the present invention.
2 is a diagram illustrating a smelting apparatus used for smelting tantalum using a metal thermal reduction method according to an embodiment of the present invention.
3 is an XRD analysis graph of tantalum smelted according to an embodiment of the present invention.
4 is an SEM / EDS analysis photograph of smelted tantalum according to an embodiment of the present invention.
5 is a graph of measuring the temperature, pressure, and oxygen content of the smelted tantalum powder of the tantalum process according to the diluent concentration according to the embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention are provided to more completely explain the technical idea of the present invention to those of ordinary skill in the art, and the following examples may be modified in various other forms, The scope of the technical idea is not limited to the following examples. Rather, these embodiments are provided in order to more fully and complete the present disclosure, and to fully convey/completely the technical spirit of the present invention to those skilled in the art. As used herein, the term “and/or” includes any one and all combinations of one or more of those listed items. The same symbols refer to the same elements from time to time. Furthermore, various elements and regions in the drawings are schematically drawn. Therefore, the technical spirit of the present invention is not limited by the relative size or spacing drawn in the accompanying drawings.

1 is a flowchart schematically illustrating a method for smelting tantalum using a metal thermal reduction method according to an embodiment of the present invention. The method for smelting tantalum using a metal thermal reduction method according to the present invention includes a step of heating a raw material containing tantalum and a diluent, an incremental input of a reducing agent, and a step of generating tantalum.

2 is a diagram illustrating a smelting apparatus used for smelting tantalum using a metal thermal reduction method according to an embodiment of the present invention. The smelting apparatus may include a housing 10 , a reaction vessel 20 , a thermocouple 30 , a stirrer 40 , a reducing agent injector 50 , and a controller 60 . The metal thermal reduction is performed in a smelting apparatus, and the smelting apparatus may include a vacuum means for preventing tantalum from being oxidized by combining with oxygen, and a heating means for heating the reaction vessel to an appropriate temperature, and to accelerate the reduction reaction To this, it may include a stirrer 40 for stirring the reactants. In particular, it may include a reducing agent injector 50 for incrementally inputting the reducing agent.

In particular, when selecting a structural material for a smelting apparatus, Ni is suitable as an optimal structural material. STS(Fe) reacts with Ta to form a TaFe ₂ phase over the entire temperature range (0 to 1,000°C). Mo and Ni do not react with reducing agents, raw materials, diluents, etc., so they are stable in all temperature ranges. Considering chemical stability and price, it can be seen that Ni is suitable as an optimal structural material.

The heating of the raw material and the diluent is a step of charging and heating the raw material and the diluent including tantalum in the reaction vessel. The raw material is K ₂ TaF ₇ , This can be obtained by dissolving tantalum ore in a mixed solution of hydrofluoric acid and sulfuric acid, followed by filtration and solvent extraction using methyl isobutyl ketone (MIBK), and crystallizing K ₂ TaF ₇ . This process may be repeatedly performed several times in order to lower the level of impurity, in particular, the level of niobium (Nb).

When heating without the diluent, the reaction temperature may increase and damage to the equipment may occur. The diluent may be at least one selected from NaCl, KCl, LiCl, and KF. As a result of confirming the physical property values of each diluent, NaCl > KCl > KF is advantageous according to the HSC chemistry calculation for the endothermic value, the solubility is KF > NaCl > KCl, and the melting point is KCl (770 ℃) < NaCl (801 ℃) < It shows the advantageous physical properties of KF (858°C). In particular, as a result of comparing thermodynamic calculations, properties, and prices, NaCl with excellent properties can be used.

When the thermodynamic calculation is confirmed, the reaction temperature is thermodynamically stabilized when 6 mol of the NaCl diluent is added per 1 mol of the K ₂ TaF ₇ raw material. However, when the K ₂ TaF ₇ raw material is added at an amount of less than 6.2 mol per 1 mol, the actual reaction temperature is too high and when it exceeds 6.7 mol, the oxygen content of the smelted tantalum is too high. Therefore, the NaCl diluent may be added in an amount of more than 6.2 mol and less than 6.7 mol per 1 mol of the K ₂ TaF ₇ raw material.

The step of incrementally adding the reducing agent is a step of incrementally adding the reducing agent into the reaction vessel. The reducing agent may be at least one selected from Ca, Na and Mg. Raw materials containing tantalum react with Na, Ca, and Mg metals to form Ta. Each by-product is Na: NaF, Ca: CaF ₂ , Mg: MgF ₂ , and the solubility of water (H ₂ O) for each by-product is NaF (40.4 g/L), CaF ₂ (0.016 g/L), MgF ₂ (0.13 g/L). When Na is used, it is possible to secure purity and shorten the process time by forming NaF, which is well soluble in water.

In addition, as a result of calculating the adiabatic temperature T _ad from 0 to 9 moles for each reducing agent, Ca (2,716 ℃ ~ 1,046 ℃), Mg (2,118 ℃ ~ 859 ℃), Na (1,771 ℃ ~ 855 ℃) to control the heat generation when using Na was confirmed to be effective.

As used herein, the term "incrementally" means to increase the amount of the reducing agent by adding the reducing agent to the reaction vessel in one or more increments or portions. The amount of increments may be the same or different. The increments may be added in stages or a combination thereof. Accordingly, the term "incremental" as used in the specification and claims includes both the continuous and stepwise addition of the reducing agent in one or more increments.

The reducing agent may be incremented 5 times at intervals of 5 minutes into the reaction vessel, and 5 to 7 mol of the reducing agent may be added per 1 mol of the raw material. By incrementally adding the reducing agent, it is possible to induce a uniform reaction between the raw material and the reducing agent, thereby minimizing unreacted raw materials and smelting high-purity tantalum with excellent yield. In addition, the mixing of trace impurities is also remarkably reduced, making it easy to control by-products. Therefore, it is possible to reduce environmental load and reduce wastewater treatment costs by reducing process by-products generated by a stable process with controlled reaction temperature and speed.

The tantalum generation step is a step in which the reducing agent and the raw material react to generate tantalum. Tantalum is produced by the reaction of K ₂ TaF ₇ + 5Na → Ta + 2KF + 5NaF with the K ₂ TaF ₇ raw material and the Na reducing agent.

The tantalum generation step may be performed at 950° C. or less. The method for smelting tantalum using the metal thermal reduction method according to the present invention can reduce environmental load and reduce wastewater treatment costs by reducing process by-products generated in a stable process with controlled reaction temperature and speed. Tantalum using the metal thermal reduction method according to the present invention may have a purity of 99.95% by weight or more, an oxygen content of 988ppm or less, and a yield of 83% or more.

That is, the smelting method of tantalum using the metal thermal reduction method according to the present invention can minimize unreacted raw materials by incrementally adding a reducing agent, thereby smelting high-purity tantalum with excellent yield. In addition, it is possible to reduce the environmental load and reduce the cost of wastewater treatment by reducing the process by-products generated by a stable process with controlled reaction temperature and speed. In addition, tantalum using the metal thermal reduction method according to the present invention may have excellent characteristics such as a purity of 99.95 wt% or more, an oxygen content of 988 ppm or less, and a yield of 83% or more.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and cannot be construed as limiting the present invention in any sense.

Content not described here will be omitted because it can be technically inferred sufficiently by a person skilled in the art.

smelting of tantalum

The smelting of tantalum using the metal thermal reduction method according to the present invention proceeded as shown in FIG. 1 in a heating step of a raw material and a diluent, an incremental inputting of a reducing agent, and a tantalum generation step.

The raw material K ₂ TaF ₇ and the diluent NaCl containing tantalum were charged into the reaction vessel and heated. The NaCl was added in 6.2, 6.5 and 6.7 mol per 1 mol of K ₂ TaF ₇ , respectively.

The reducing agent Na was added incrementally into the reaction vessel. The Na was added 5, 6, and 7 mol per 1 mol of K ₂ TaF ₇ into the reaction vessel in 5 increments at 5 minute intervals, respectively. As a comparative example, 5, 6, and 7 mol of Na per 1 mol of K ₂ TaF ₇ were added in batches.

When the reducing agent and the raw material react to produce tantalum, the produced tantalum was pulverized, washed, and dried to prepare tantalum powder. Washing was performed for 1 hour in 2% H ₂ O ₂ and 1% HF solution, and 20% (HCl+HNO ₃ ) solution for 1 hour.

Evaluation of Tantalum Powder Properties

The physical properties of the smelted tantalum powder according to the manufacturing method were evaluated. 3 is an XRD analysis graph of tantalum smelted by incrementally adding 5, 6, and 7 mol of a reducing agent per 1 mol of raw material, and FIG. 4 is a smelting by incrementally adding 5, 6 and 7 mol of reducing agent per 1 mol of raw material. SEM/EDS analysis picture of tantalum. Single-phase Ta was confirmed by XRD confirmation, and it was confirmed by EDS analysis that no impurities other than Ta were detected.

Table 1 below shows the purity, oxygen content, and final yield of the tantalum powder smelted by batch input and incremental input of 5, 6, and 7 mol per mol of the raw material as a reducing agent according to an embodiment of the present invention.

reducing agent content batch input Incremental input water
(ICP analysis)
weight% 5 mol 99.92 99.95 6 mol 99.97 99.99 7 mol 99.96 99.98 oxygen content
(ICP analysis)
weight% 5 mol 1076 988 6 mol 868 824 7 mol 894 834 final yield
% 5 mol 72 83 6 mol 87 92 7 mol 85 89

As shown in Table 1, it can be seen that as the reducing agent Na is incrementally added, it is advantageous for purity and oxygen content, and tantalum refined under the condition that 5 to 7 mol Na reducing agent per 1 mol of raw material is incremented 5 times at 5 minute intervals It was confirmed that the silver purity was 99.95% by weight or more, the oxygen content was 988ppm or less, and had a yield of 83% or more.

[Effect of Incremental Input]

If the reducing agent is added incrementally regardless of the reducing agent content, purity, oxygen content, and yield are all improved. It is groundbreaking that Ta with a purity of 99.99% can be obtained only by incrementally adding a reducing agent without an additional refining process. With the incremental addition of reducing agent, it is noticeable that the final yield is improved by 4-11% with the improvement of purity.

[Effect of exceeding the stoichiometric ratio]

When the reducing agent is added in excess of the stoichiometric ratio, purity, oxygen content, and yield are all improved. When the reducing agent content is increased from the stoichiometric ratio of 5 mol to 6 mol, the purity and yield increase, the oxygen content decreases, and the reducing agent content decreases. When it becomes 7 mol, the purity, oxygen content, and yield are slightly lower than when the reducing agent is 6 mol. Therefore, the reducing agent is preferably added in excess of the stoichiometric ratio, more preferably in the range of more than 5 mol to 7 mol and 6 to 7 mol.

As above, incremental input of reducing agent can induce a uniform reaction between raw materials and reducing agent due to external supply, so recovery rate without unreacted raw materials is increased, and the mixing of trace impurities is remarkably reduced, so it is easy to control by-products. did

Table 2 below shows process conditions of an experiment in which 6.2, 6.5, and 6.7 mol of a diluent per 1 mol of a raw material, respectively, were added according to an embodiment of the present invention. 5 is a graph of measuring the temperature, pressure, and oxygen content of the smelted tantalum powder of the tantalum process according to the diluent concentration under the process conditions of Table 2;

K ₂ TaF ₇ Na NaCl Input method fair atmosphere 1 mol 6 mol 6.7 mol Inject Na34.48g 6.896g 5 times every 5 minutes Oxygen: within 660ppm
Moisture: 0.1ppm
Internal pressure: 0.1psi 1 mol 6 mol 6.5 mol Inject Na34.48g 6.896g 5 times every 5 minutes Oxygen: less than 30ppm
Moisture: 0.1ppm
Internal pressure: 0.1psi 1 mol 6 mol 6.2 mol Inject Na34.48g 6.896g 5 times every 5 minutes Oxygen: less than 30ppm
Moisture: 0.1ppm
Internal pressure: 0.1psi

When the thermodynamic calculation is confirmed, the reaction temperature is thermodynamically stabilized when 6 mol of the NaCl diluent is added per 1 mol of the K ₂ TaF ₇ raw material. However, as shown in FIG. 5 , when the K ₂ TaF ₇ raw material is added at an amount of 6.2 mol or less per 1 mol, the actual reaction temperature exceeds 1000° C., so it is too high. In addition, when 6.7 mol or more of the diluent is added per 1 mol of K ₂ TaF ₇ raw material, the reaction temperature and oxygen content tend to increase. Therefore, the NaCl diluent is preferably added in excess of 6.2 mol per 1 mol of the K ₂ TaF ₇ raw material, and more preferably more than 6.2 mol and less than 6.7 mol.

As described above, in the method for smelting tantalum using the thermal reduction method according to the present invention, it is possible to smelt high-purity tantalum with excellent yield by minimizing unreacted raw materials by incrementally adding a reducing agent. In addition, it is possible to reduce the environmental load and reduce wastewater treatment costs by reducing the process by-products generated by a stable process with controlled reaction temperature and speed. It may have a higher yield.

The technical spirit of the present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is the technical spirit of the present invention that various substitutions, modifications and changes are possible without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill in the art to which this belongs.

10: housing 20: reaction vessel
30: thermocouple 40: agitator
50: reducing agent input device 60: controller

Claims (11)

In the tantalum smelting method,
Batch charging and heating the raw material and the diluent containing tantalum in the reaction vessel;
incrementally introducing a reducing agent into the reaction vessel; and
and the step of reacting the reducing agent with the raw material to produce tantalum,
The reducing agent is one or more selected from Ca, Na and Mg, and 5 to 7 mol is added per 1 mol of the raw material,
In the incrementally inputting step, by incrementally introducing the reducing agent into the reaction vessel 5 times at an interval of 5 minutes,
The tantalum generation step is performed at 950 ° C. or less to reduce process by-products in a stable process in which the reaction temperature and speed are controlled, and the final yield is improved by 4 to 11%, and the purity of the smelted tantalum is 99.95 wt% or more, oxygen A method for smelting tantalum using a metal thermal reduction method, characterized in that the content is 988 ppm or less and the final yield is 83% or more.
According to claim 1,
The raw material is K ₂ TaF ₇ Method for smelting tantalum using a metal thermal reduction method, characterized in that
According to claim 1,
The diluent is at least one selected from NaCl, KCl, LiCl, and KF. Method for smelting tantalum using a thermal reduction method
4. The method of claim 3,
The diluent is a method of smelting tantalum using a metal thermal reduction method, characterized in that more than 6.2 mol and less than 6.7 mol is added per 1 mol of the raw material.
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