A method for producing a tantalum carbide using lithium tantalate

Abstract

The application discloses a method for preparing carbonized tantalum by using lithium tantalate, comprising the following steps: S1, grinding and crushing lithium tantalate wafer into powder; S2, mixing the lithium tantalate powder with carbon black to obtain a first mixture; S3, placing the first mixture into a carbonization furnace to perform primary carbonization, secondary carbonization and tertiary carbonization; after the tertiary carbonization, a second mixture of carbonized tantalum with an oxygen content of 5000-10000 ppm is obtained; S4, grinding and crushing the second mixture to obtain a third mixture; and S5, heating the third mixture to 1500-1700 DEG C in a vacuum furnace, and discharging the furnace to obtain finished carbonized tantalum; the preparation method of the application adopts a direct carbonization method to recycle and utilize lithium tantalate, skips a wet process step, avoids fluorine pollution, and has double values of resource circulation and economic benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of preparation of tantalum carbide, and more particularly to a method for preparing tantalum carbide by using lithium tantalate. BACKGROUND

[0002] The lithium tantalate wafer has excellent electro-optic, piezoelectric, acousto-optic and other characteristics, and its application covers high-end electronics, communication, medical treatment and other fields. The yield in the production process is also affected by multiple factors, so 10% of the total capacity will enter the scrap market. Recycling of waste lithium tantalate can reduce the dependence on primary minerals, extend the resource use cycle. At present, waste lithium tantalate is mainly recycled by hydrometallurgy. This kind of recycling needs to use HF / HSO4 system to dissolve tantalum, which will produce fluorine-containing wastewater, and the process needs repeated extraction, and the recovery rate of tantalum is also low.

[0003] As a typical superhard metal carbide, tantalum carbide is widely used in cutting tools, aerospace heat-resistant coatings and other fields due to its high melting point, high hardness and excellent chemical stability. The traditional preparation of tantalum carbide relies on high-purity tantalum powder and graphite high-temperature reaction (>1800℃), which is costly. If waste lithium tantalate can be used as raw material to directly synthesize tantalum carbide, the production cost can be significantly reduced, but the technical difficulty lies in impurity separation and carbonization efficiency, so a recycling process with dual values of resource recycling and economic benefits is needed to utilize waste lithium tantalate wafer to prepare tantalum carbide.

[0004] Publication No. CN116947047A discloses a preparation method of tantalum carbide powder, which comprises the following steps: (1) mixing tantalum oxide powder and carbon black powder into a carbon boat; (2) pushing the carbon boat containing the mixture into a carbon tube furnace to make the tantalum oxide in the carbon boat react with the carbon black; (3) pushing the carbon boat out of the carbon tube furnace and cooling to obtain tantalum carbide; (4) ball milling and sieving; (5) performance testing to obtain tantalum carbide powder; the preparation method uses tantalum oxide powder as raw material, which has high cost, resulting in low economic benefit of the method. SUMMARY

[0005] To solve the problems of fluorine pollution caused by hydrometallurgical recovery of lithium tantalate and low recovery rate of hydrometallurgical tantalum, and the problem of high cost of traditional preparation of tantalum carbide relying on high-purity tantalum powder and graphite high-temperature reaction, a method for preparing tantalum carbide by using lithium tantalate is provided.

[0006] The technical scheme of the present application is:

[0007] A method for preparing tantalum carbide by using lithium tantalate, comprising the following steps:

[0008] S1, grinding and crushing lithium tantalate wafer into powder;

[0009] S2, mixing the lithium tantalate powder with carbon black to obtain a first mixture;

[0010] S3, placing the first mixture into a carbonization furnace to perform primary carbonization at a carbonization temperature of 1200-1400 DEG C for 5-7 hours, secondary carbonization at a carbonization temperature of 1400 DEG C-1500 DEG C for 5-7 hours, and tertiary carbonization at a carbonization temperature of 1500 DEG C-1600 DEG C for 5-7 hours, to obtain a second mixture of carbonized tantalum with an oxygen content of 5000-10000 ppm;

[0011] S4, grinding and crushing the second mixture to obtain a third mixture;

[0012] S5, heating the third mixture in a vacuum furnace to 1500-1700 DEG C for 11-13 hours, and then introducing cooling gas to cool, to obtain a finished product of carbonized tantalum.

[0013] Further, the particle size of the lithium tantalate after grinding in S1 is ≤100 mesh.

[0014] Further, in S2, the mass ratio of the lithium tantalate powder to carbon black is 1:0.25-0.4.

[0015] Further, the mixing time in S2 is 6-7 hours.

[0016] Further, the carbonization furnace is a horizontal furnace, and the feeding mode is continuous pushing.

[0017] Further, the particle size of the third mixture in S4 is ≤100 mesh.

[0018] Further, the vacuum degree of the vacuum furnace in S5 is 1 Pa-10 Pa.

[0019] Further, the products of the primary carbonization, the secondary carbonization, the tertiary carbonization in S3, and the product of the furnace discharge in S5 are subjected to chemical component detection.

[0020] Further, the chemical component detection items of the furnace discharge product include the carbon content, the oxygen content, the nitrogen content, the Li content, and the tantalum content of the product.

[0021] Further, the cooling gas is argon.

[0022] Compared with the prior art, the application has the beneficial effects that:

[0023] The preparation method of the application recycles and utilizes lithium tantalate by direct carbonization, skips the wet process, avoids fluorine pollution, and has dual values of resource recycling and economic benefits.

[0024] The preparation method is simple in steps, and the prepared carbonized tantalum product has a mass fraction of more than 99%. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A process flow chart of a method for preparing carbonized tantalum by using lithium tantalate. DETAILED DESCRIPTION

[0026] In order to clearly illustrate the technical solutions of the present application, the following will give a detailed description of the present application with reference to the drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in other ways different from those described herein. Therefore, the protection scope of the present application is not limited by the specific embodiments disclosed below. In addition, in the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified. In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected, or it can be communicated; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication or interaction relationship of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0027] Embodiment 1

[0028] The present embodiment provides a method for preparing tantalum carbide by using lithium tantalate, comprising the following steps:

[0029] S1, grinding the lithium tantalate wafer into powder, the step uses a ball mill to grind, the particle size of the lithium tantalate powder is controlled, and the particle size after grinding is required to be ≤100 mesh.

[0030] S2, mixing the lithium tantalate powder and carbon black to obtain a first mixture, the first mixture is fully mixed in a mixer, and the mixing time is controlled to be 6-7 h, wherein the mass ratio of the lithium tantalate powder to the carbon black is 1:0.25.

[0031] S3, the first mixture is placed into a carbonization furnace for primary carbonization, the carbonization temperature is 1200℃, the carbonization time is 5h; secondary carbonization, the carbonization temperature is 1400℃, the time is 5h; tertiary carbonization, the carbonization temperature is 1500℃, the time is 5h; after the tertiary carbonization, a second mixture of carbonized tantalum with an oxygen content of 5000-10000ppm is obtained. Because the structure of the carbonization furnace is relatively simple, it is a horizontal furnace, and the furnace body is an elongated cylinder, the mixture is pushed by a screw during the carbonization process in the carbonization furnace, enters from one end and exits from the other end, and the heating reaction is carried out in a non-vacuum environment, which is subject to the external environment (non-vacuum), so the gas impurities cannot be further reduced, and must be subjected to the next reaction in a vacuum furnace to further reduce. If the carbonization is continuously heated, a dynamic balance will exist, and part of the oxygen will react with the carbonized tantalum to form tantalum oxide, so it is necessary to monitor the oxygen content of the product after the tertiary carbonization.

[0032] S4, the second mixture is broken into a third mixture, and the particle size of the third mixture is ≤100 mesh, so that the subsequent reaction can be more efficient and sufficient.

[0033] S5, the third mixture is heated to 1500℃ in a vacuum furnace, cooled by introducing cooling gas after holding for 11h, and the tantalum carbide product is obtained, the vacuum degree of the vacuum furnace in S5 is controlled to be 1Pa-10Pa, and the cooling gas is argon.

[0034] Chemical composition detection is performed on the products of the primary carbonization, the secondary carbonization, the tertiary carbonization in S3 and the product after the furnace is discharged in S5, wherein the detection items include the carbon content, the oxygen content, the nitrogen content, the Li content and the tantalum content of the product, and the detection data are shown in Table 1.

[0035] Table 1: detection results in Example 1

[0036]

[0037] As shown by the data in Table 1, the lithium content in the final vacuum furnace product is 0, indicating that lithium has been transferred in the form of gas during the high-temperature carbonization process, realizing the separation of tantalum and lithium; the oxygen and nitrogen contents also meet the quality requirements, and the mass fraction of the carbonized tantalum gradually increases during the carbonization process, and finally reaches 99.45%.

[0038] Example 2

[0039] The embodiment provides a method for preparing carbonized tantalum by using lithium tantalate, and comprises the following steps:

[0040] S1, grinding lithium tantalate wafer into powder, the step of grinding is performed by using a ball mill, the particle size of the lithium tantalate powder is controlled by grinding, and the particle size after grinding is required to be less than or equal to 100 mesh.

[0041] S2, mixing the lithium tantalate powder and carbon black to obtain a first mixture, the first mixture is fully mixed in a mixer, and the mixing time is controlled to be 7 hours, wherein the mass ratio of the lithium tantalate powder to the carbon black is 1:0.4.

[0042] S3, placing the first mixture into a carbonization furnace to perform primary carbonization, the carbonization temperature is 1300 DEG C, and the carbonization time is 7 hours; secondary carbonization is performed at a carbonization temperature of 1450 DEG C for 7 hours; tertiary carbonization is performed at a carbonization temperature of 1550 DEG C for 7 hours; the second mixture of carbonized tantalum with an oxygen content of 30000-40000 ppm is obtained after the tertiary carbonization; wherein the heating rate of the primary carbonization, the secondary carbonization and the tertiary carbonization is 5-10 DEG C / min, and the temperature is kept constant after the heating is completed.

[0043] S4, grinding the second mixture to obtain a third mixture, the particle size of the third mixture is less than or equal to 100 mesh, and the third mixture after grinding can make the subsequent reaction more efficient and sufficient.

[0044] S5, heating the third mixture to 1600 DEG C in a vacuum furnace, introducing cooling gas to cool after heat preservation for 13 hours, and taking out the furnace to obtain a carbonized tantalum product, the vacuum degree of the vacuum furnace in S5 is controlled to be 10 Pa-1 Pa, and the cooling gas is argon.

[0045] Chemical composition detection is performed on the products of the primary carbonization, the secondary carbonization, the tertiary carbonization in S3 and the product taken out of the furnace in S5, wherein the detection items include the carbon content, the oxygen content, the nitrogen content, the Li content and the tantalum content of the product, and the detection data are shown in the following table 2.

[0046] Table 2: detection results in example 2

[0047]

[0048] It can be known from the data in table 2 that the lithium content in the final product of the vacuum furnace is 0%, which indicates that the lithium is transferred in the form of gas in the high-temperature carbonization process, and the separation of tantalum and lithium is realized; the oxygen and nitrogen contents also meet the quality requirements, and the mass fraction of the carbonized tantalum gradually increases with the carbonization process, and finally reaches 99.48%.

[0049] Example 3

[0050] The embodiment provides a method for preparing carbonized tantalum by using lithium tantalate, and comprises the following steps:

[0051] S1, grinding lithium tantalate wafer into powder, the step uses a ball mill to grind, and the particle size of the lithium tantalate powder is controlled; and the particle size after grinding is required to be less than or equal to 100 mesh.

[0052] S2, mixing the lithium tantalate powder and carbon black to obtain a first mixture, the first mixture is fully mixed in a stirrer, and the mixing time is controlled to be 6-7 hours; and the mass ratio of the lithium tantalate powder to the carbon black is 1:0.25-0.4.

[0053] S3, placing the first mixture into a carbonization furnace to perform primary carbonization, the carbonization temperature is 1400 DEG C, and the carbonization time is 6 hours; performing secondary carbonization, the carbonization temperature is 1500 DEG C, and the carbonization time is 6 hours; performing tertiary carbonization, the carbonization temperature is 1600 DEG C, and the carbonization time is 6 hours; and the carbonized tantalum second mixture with an oxygen content of 5000-10000 ppm is obtained after the tertiary carbonization; wherein the heating rate of the primary carbonization, the secondary carbonization and the tertiary carbonization is 5-10 DEG C / min, and the temperature is kept constant after the heating is completed.

[0054] S4, grinding the second mixture to obtain a third mixture, and the particle size of the third mixture is less than or equal to 100 mesh, so that the subsequent reaction can be more efficient and sufficient.

[0055] S5, heating the third mixture to 1700 DEG C in a vacuum furnace, introducing cooling gas to cool after heat preservation for 11-13 hours, and taking out the furnace to obtain a carbonized tantalum product, the vacuum degree of the vacuum furnace in S5 is controlled to be 10 Pa-1 Pa, and the cooling gas is argon.

[0056] Chemical composition detection is performed on the products of the primary carbonization, the secondary carbonization, the tertiary carbonization in S3 and the product taken out of the furnace in S5, and the detection items include the carbon content, the oxygen content, the nitrogen content, the Li content and the tantalum content of the product, and the detection data are shown in Table 3.

[0057] Table 3: detection results in the embodiment 3

[0058]

[0059] It can be known from the data in Table 3 that the lithium content in the final product of the vacuum furnace is 0, which indicates that the lithium is transferred in the form of gas in the high-temperature carbonization process, and the separation of tantalum and lithium is realized; the oxygen and nitrogen contents also meet the quality requirements, and the mass fraction of the carbonized tantalum gradually increases in the carbonization process, and finally reaches 99.5%. The above embodiments show that the preparation method has good impurity separation effect, and the carbonization rate can reach more than 99%.

[0060] Obviously, the above embodiments of the present application are merely exemplary but not intended to limit the embodiments of the present application. Based on the above description, any other variations or changes can be made by those skilled in the art without departing from the spirit and principles of the present application. It is not necessary to list all the embodiments here. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application should be included in the protection scope of the claims of the present application.

Claims

1. A method for producing a tantalum carbide using a lithium tantalate, characterized by, The method comprises the following steps: S1, grinding and crushing lithium tantalate wafer into powder; S2, mixing the lithium tantalate powder with carbon black to obtain a first mixture; S3, placing the first mixture into a carbonization furnace for primary carbonization at a temperature of 1200-1400 DEG C for 5-7 hours, secondary carbonization at a temperature of 1400-1500 DEG C for 5-7 hours, and tertiary carbonization at a temperature of 1500-1600 DEG C for 5-7 hours, to obtain a second mixture of carbonized tantalum with an oxygen content of 5000-10000 ppm; S4, grinding and crushing the second mixture to obtain a third mixture; S5, heating the third mixture in a vacuum furnace to 1500-1700 DEG C for 11-13 hours, and then introducing cooling gas to cool, and finally obtaining carbonized tantalum product.

2. The method for preparing the carbonized tantalum using the lithium tantalate according to claim 1, wherein, The particle size of the lithium tantalate after grinding in S1 is less than or equal to 100 mesh.

3. The method for preparing the carbonitride of tantalum using the lithium tantalate according to claim 1, characterized by, In S2, the mass ratio of the lithium tantalate powder to carbon black is 1:0.25-0.

4.

4. The method of claim 1, wherein the lithium tantalate is prepared by the steps of: preparing a lithium tantalate precursor; and heating the lithium tantalate precursor at a temperature of 800-1,000°C for 1-10 hours in an atmosphere of nitrogen or argon. The mixing time in S2 is 6-7 hours.

5. The method of claim 1, wherein the lithium tantalate is prepared by the steps of: preparing a lithium tantalate precursor; and heating the lithium tantalate precursor at a temperature of 600- 1,000°C for 1-10 hours in an atmosphere of nitrogen, argon, or vacuum. The carbonization furnace is a horizontal furnace, and the feeding mode is continuous pushing.

6. The method of claim 1, wherein the lithium tantalate is prepared by the steps of: preparing a lithium tantalate precursor; and heating the lithium tantalate precursor at a temperature of 600- 1,000°C for 1-10 hours in an atmosphere of nitrogen, argon, or vacuum. The particle size of the third mixture in S4 is less than or equal to 100 mesh.

7. The method of claim 1, wherein the lithium tantalate is prepared by a method comprising: preparing a lithium tantalate precursor; and heating the lithium tantalate precursor in a carbon source. The vacuum degree of the vacuum furnace in S5 is 1-10 Pa.

8. The method of claim 1, wherein the lithium tantalate is prepared by the steps of: preparing a lithium tantalate precursor; and heating the lithium tantalate precursor at a temperature of 600- 1,000°C for 1-10 hours in an atmosphere of nitrogen, argon, or vacuum. The products after primary carbonization, secondary carbonization, tertiary carbonization in S3 and after being taken out of the furnace in S5 are subjected to chemical composition detection.

9. The method of claim 8, wherein the lithium tantalate is prepared by a method comprising: preparing a lithium tantalate precursor; and heating the lithium tantalate precursor in a carbon source. The chemical composition detection items of the products taken out of the furnace include carbon content, oxygen content, nitrogen content, Li content, and tantalum content.

10. The method of claim 1, wherein the lithium tantalate is prepared by the steps of: preparing a lithium tantalate precursor; and heating the lithium tantalate precursor to a temperature of 600- 1000 °C in a reducing atmosphere. The cooling gas is argon.

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