Preparation method of ultra-coarse tungsten powder

Abstract

The invention relates to the technical field of powder metallurgy, in particular to a preparation method of ultra-coarse tungsten powder. The preparation method of the ultra-coarse tungsten powder comprises the following steps that a second material layer is laid on a first material layer, and after dry hydrogen reduction and screening are conducted in sequence, the ultra-coarse tungsten powder is obtained; wherein the first material layer comprises a tungsten-containing raw material with a first particle size, the second material layer comprises a tungsten-containing raw material with a second particle size, and the first particle size is larger than the second particle size. According to the preparation method of the ultra-coarse tungsten powder, a doping agent does not need to be added, dry hydrogen reduction is used, process conditions are easy to control, the corrosion effect of water vapor on equipment is relieved, and the product consistency and purity of the ultra-coarse tungsten powder are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of powder metallurgy, and in particular to a method for preparing super-coarse tungsten powder. Background Art

[0002] Super-coarse tungsten powder has good strength and toughness and is widely used in many fields. For example, in the manufacturing of cemented carbide tools, geological and mining tools, stamping die manufacturing, oil drilling and production industries, artificial diamond production, high-speed cutting tools, furnace structure materials, jet engine components, cermet materials, resistance heating elements, and hard-facing materials, etc.

[0003] Currently, the preparation of super-coarse tungsten powder includes the following methods. High-temperature reduction method: In a two-zone molybdenum wire furnace, tungsten oxide powder is reduced with hydrogen at a high temperature of about 1200 °C to obtain tungsten powder; however, the particle size of the obtained tungsten powder can only reach 7 - 15 μm. Doping and thickening method: A mixed solution of sodium tungstate and ammonium tungstate is heated, concentrated, evaporated, and dried to obtain a precursor of a crystalline mixture of ammonium paratungstate and sodium tungstate, which is sieved to make -80 mesh powder, and then fine tungsten powder return material is added and mixed, and then hydrogen is introduced into a tubular reduction furnace for reduction to obtain super-coarse tungsten powder with a particle size of 60 - 150 μm; however, in this method, doping agents such as sodium salts are used for thickening, and the prepared tungsten powder will have doping agent residues, affecting the purity of the tungsten powder. Undoped humid reduction method: High specific surface area and large particle blue tungsten are subjected to humid reduction by introducing water vapor and hydrogen in a three-zone high-temperature molybdenum wire furnace, and after cooling and sieving, super-coarse tungsten powder is obtained; although the humid hydrogen reduction method solves the problem of doping agent residues, there may be the following disadvantages in preparing tungsten powder with humid hydrogen: Oxygen content problem: Humid hydrogen contains a certain amount of water vapor, which may lead to a relatively high oxygen content in the prepared tungsten powder. For example, if there is no reasonable process control, the oxygen content in the tungsten powder may exceed expectations, affecting the purity of the tungsten powder and the performance of subsequent products; Powder agglomeration problem: During the humid hydrogen reduction process, tungsten powder particles may be more likely to agglomerate, making the dispersibility of the powder worse and affecting its uniformity and stability in subsequent processing and applications; Particle size distribution is difficult to precisely control: Although humid hydrogen conditions are helpful for the growth of tungsten powder particles in some cases, due to factors such as hydrogen humidity and water vapor partial pressure being difficult to precisely and stably control in actual production, the particle size distribution range of tungsten powder produced in the same batch may be relatively large, resulting in poor product consistency; Complex production process: Preparing tungsten powder with humid hydrogen may require additional equipment or measures to control parameters such as hydrogen humidity and dew point, increasing the complexity of the production process and cost investment; Equipment corrosion risk: The water vapor present in the humid hydrogen environment may have a certain corrosive effect on the production equipment, which may affect the service life and performance of the equipment in the long term and increase the equipment maintenance cost.

[0004] In view of this, this invention is specifically proposed. Summary of the Invention

[0005] The object of the present invention is to provide a method for preparing ultra-coarse tungsten powder, which does not require the addition of dopants, uses dry hydrogen reduction, has process conditions that are easy to control, alleviates the corrosion effect of water vapor on equipment, and improves the product consistency and purity of ultra-coarse tungsten powder.

[0006] In order to achieve the above object of the present invention, the following technical solutions are specifically adopted:

[0007] The present invention provides a method for preparing ultra-coarse tungsten powder, comprising the following steps:

[0008] Lay the second material layer on the first material layer, and after performing dry hydrogen reduction and screening in sequence, obtain the ultra-coarse tungsten powder;

[0009] Wherein, the first material layer comprises a tungsten-containing raw material with a first particle size, the second material layer comprises a tungsten-containing raw material with a second particle size, and the first particle size is greater than the second particle size.

[0010] Further, the tungsten-containing raw material comprises blue tungsten and / or tungsten oxide.

[0011] Further, the first material layer comprises a tungsten-containing raw material with a particle size of 30 - 35 μm, and the second material layer comprises a tungsten-containing raw material with a particle size of 2 - 5 μm.

[0012] Further, the mass ratio of the tungsten-containing raw material with a particle size of 30 - 35 μm to the tungsten-containing raw material with a particle size of 2 - 5 μm is (8 - 12):1.

[0013] Further, the total thickness of the second material layer and the first material layer is 2 - 5 cm.

[0014] Further, the hydrogen flow rate for the dry hydrogen reduction is 3 - 8 m 3 / h.

[0015] Further, the temperature for the dry hydrogen reduction is 900 - 1400 °C.

[0016] Further, the time for the dry hydrogen reduction is 5 - 10 h.

[0017] Further, the device for the dry hydrogen reduction comprises a fifteen-tube furnace.

[0018] Further, the Fisher particle size of the ultra-coarse tungsten powder is 35 - 40 μm.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. In the method for preparing ultra-coarse tungsten powder of the present invention, there is no need to add dopants, avoiding the problem that dopant residues affect the purity of tungsten powder.

[0021] 2. The preparation method of the ultra-coarse tungsten powder of the present invention adopts dry hydrogen reduction, and improves the particle size of the tungsten powder by making full use of the water generated by the reduction reaction itself, solving the problems of difficult process control in the wet hydrogen reduction method and corrosion of equipment by water.

[0022] 3. The preparation method of the ultra-coarse tungsten powder of the present invention makes the particle size distribution of the tungsten powder product more concentrated, improving the product consistency. Specific Embodiments

[0023] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer can be obtained as conventional products through commercial purchase.

[0024] The preparation method of an ultra-coarse tungsten powder according to an embodiment of the present invention will be specifically described below.

[0025] In some embodiments of the present invention, a preparation method of ultra-coarse tungsten powder is provided, including the following steps:

[0026] Lay the second material layer on the first material layer, and after dry hydrogen reduction and screening in sequence, ultra-coarse tungsten powder is obtained;

[0027] Among them, the first material layer includes tungsten-containing raw materials with a first particle size, and the second material layer includes tungsten-containing raw materials with a second particle size, and the first particle size is larger than the second particle size.

[0028] In the preparation method of the ultra-coarse tungsten powder of the present invention, no dopant needs to be added, avoiding the problem that the dopant residue affects the purity of the tungsten powder.

[0029] Water is the key factor for the growth of tungsten powder particle size. The present invention uses dry hydrogen and improves the tungsten powder particle size by making full use of the water generated by the reduction reaction itself, solving the problems of difficult process control in the wet hydrogen reduction method and corrosion of equipment by water.

[0030] In the present invention, by laying a layer of tungsten-containing raw materials with a larger particle size on the lower layer and a layer of tungsten-containing raw materials with a smaller particle size on the upper layer, fine tungsten powder with higher activity is generated on the upper layer. It reacts more easily with water vapor to generate water and tungsten oxide. The concentration of hydrated tungsten oxide gas on the surface of the upper layer raw materials increases, and more hydrated tungsten oxide vapor is reduced by hydrogen and deposited on the upper layer tungsten particles, causing the particle size of the upper layer tungsten powder to grow. This process reduces the particle size difference between the upper and lower layers of tungsten powder, makes the particle size distribution of the tungsten powder product more concentrated, and improves the product consistency.

[0031] In some embodiments of the present invention, the tungsten-containing raw material includes blue tungsten and / or tungsten oxide; blue tungsten or tungsten oxide can be obtained by calcining ammonium paratungstate (APT) to obtain blue tungsten or tungsten oxide with different particle size distributions; preferably, the tungsten-containing raw material includes blue tungsten.

[0032] In some embodiments of the present invention, the first material layer includes a tungsten-containing raw material with a particle size of 30 - 35 μm (for example, the particle size can be 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, etc.), and the second material layer includes a tungsten-containing raw material with a particle size of 2 - 5 μm (for example, the particle size can be 2 μm, 3 μm, 4 μm, 5 μm, etc.).

[0033] The present invention uses raw materials with different particle size distributions to prepare ultra-coarse tungsten powder. The tungsten-containing raw material with a particle size of 30 - 35 μm is placed in the lower layer of the boat, and a layer of tungsten-containing raw material with a particle size of 2 - 5 μm is spread on the upper layer; the reduction is carried out step by step from the upper layer raw material to the lower layer raw material. When the coarser raw material in the lower layer is reduced, the water vapor generated needs a certain time to diffuse outwards, and since a layer of finer raw material is spread on the upper layer, there is a certain hindrance to the overflow of water vapor. The residence time of water vapor in the raw material becomes longer, and the water vapor will oxidize the reduced tungsten powder to form hydrated tungsten oxide, which will volatilize into a gas under these process conditions and then be reduced by hydrogen again to form tungsten powder and deposit on the larger tungsten powder particles, causing the particle size of the lower layer tungsten powder to grow; the finer raw material in the upper layer has a small particle size, high activity, and more sufficient contact with hydrogen, so it is preferentially reduced by hydrogen to generate fine tungsten powder with high activity. When the water vapor generated by the reaction in the lower layer overflows to the upper layer of the raw material, it will react with the already reduced fine tungsten powder to form hydrated tungsten oxide, which will volatilize into a gas under these process conditions and then be reduced by hydrogen again to form tungsten powder and deposit on the larger tungsten powder particles, causing the particle size of the upper layer tungsten powder to grow.

[0034] Using a tungsten-containing raw material with a particle size of 30 - 35 μm, the particle size is relatively large, which is beneficial for making ultra-coarse tungsten powder, and raw materials in this particle size range are easy to prepare; using a tungsten-containing raw material with a particle size of 2 - 5 μm, the particle size is small, the activity is high, the reaction rate in the upper layer is relatively fast, the generated tungsten powder has a finer particle size and high activity, and it reacts with the generated water vapor to form volatile hydrated tungsten oxide, which is reduced by hydrogen and deposited on the tungsten powder, causing the particle size of the tungsten powder to grow. The tungsten powder generated from tungsten-containing raw materials with a smaller particle size is too small and is extremely easy to be oxidized, with a risk of ignition.

[0035] In some embodiments of the present invention, the mass ratio of the tungsten-containing raw material with a particle size of 30 - 35 μm to the tungsten-containing raw material with a particle size of 2 - 5 μm is (8 - 12):1; typically but not limited to, for example, the mass ratio of the tungsten-containing raw material with a particle size of 30 - 35 μm to the tungsten-containing raw material with a particle size of 2 - 5 μm can be 8:1, 9:1, 10:1, 11:1, 12:1 or any range value composed of any two of them.

[0036] When the tungsten-containing raw materials with two different particle sizes of the present invention adopt the above mass ratio range, not only can ultra-coarse tungsten powder be prepared, but also the raw materials are fully utilized, and the proportion of the finer tungsten powder as a by-product screened out subsequently is relatively low; when the mass ratio is relatively large, the proportion of the fine-grained raw materials is low, and the contribution to the growth of tungsten powder is limited; when the mass ratio is relatively small, the proportion of the fine raw materials is relatively large, and there will be a large amount of fine tungsten powder by-products subsequently.

[0037] In some embodiments of the present invention, the total thickness of the second material layer and the first material layer is 2-5 cm; typically but not restrictively, for example, the total thickness of the second material layer and the first material layer can be 2 cm, 3 cm, 4 cm, 5 cm or the range value composed of any two of them.

[0038] In some embodiments of the present invention, the hydrogen flow rate for dry hydrogen reduction is 3-8 m 3 / h; typically but not restrictively, for example, the hydrogen flow rate for hydrogen reduction can be 3 m 3 / h, 4 m 3 / h, 5 m 3 / h, 6 m 3 / h, 7 m 3 / h, 8 m 3 / h or the range value composed of any two of them.

[0039] In some embodiments of the present invention, the temperature for dry hydrogen reduction is 900-1400 °C; typically but not restrictively, for example, the temperature for dry hydrogen reduction can be 900 °C, 1000 °C, 1100 °C, 1200 °C, 1300 °C, 1400 °C or the range value composed of any two of them.

[0040] In some embodiments of the present invention, the time for dry hydrogen reduction is 5-10 h; typically but not restrictively, for example, the time for dry hydrogen reduction can be 5 h, 6 h, 7 h, 8 h, 9 h, 10 h or the range value composed of any two of them.

[0041] In some embodiments of the present invention, the device for dry hydrogen reduction includes a fifteen-tube furnace.

[0042] In some embodiments of the present invention, the Fisher grain size of the ultra-coarse tungsten powder is 35-40 μm.

[0043] Example 1

[0044] The method for preparing ultra-coarse tungsten powder provided in this example includes the following steps:

[0045] First, spread a layer of blue tungsten with a particle size of 30 - 35 μm in the boat, and then spread another layer of blue tungsten with a particle size of 2 - 5 μm. The mass ratio of the blue tungsten with a particle size of 30 - 35 μm to the blue tungsten with a particle size of 2 - 5 μm is 9:1, and the total thickness of the material layer (blue tungsten) in the boat is 3 cm;

[0046] Start the fifteen - tube furnace and set the parameters as follows: the flow rate of hydrogen (dry) is 5 m 3 / h, the temperature is 1200 °C, and the time is 6 h; Push the boat filled with the above - mentioned materials into the fully - automatic fifteen - tube furnace for dry - hydrogen reduction;

[0047] After dry - hydrogen reduction, perform screening to obtain ultra - coarse tungsten powder.

[0048] Example 2

[0049] The preparation method of the ultra - coarse tungsten powder provided in this example includes the following steps:

[0050] First, spread a layer of blue tungsten with a particle size of 30 - 35 μm in the boat, and then spread another layer of blue tungsten with a particle size of 2 - 5 μm. The mass ratio of the blue tungsten with a particle size of 30 - 35 μm to the blue tungsten with a particle size of 2 - 5 μm is 6:1, and the total thickness of the material layer (blue tungsten) in the boat is 3 cm;

[0051] Start the fifteen - tube furnace and set the parameters as follows: the flow rate of hydrogen (dry) is 5 m 3 / h, the temperature is 1200 °C, and the time is 6 h; Push the boat filled with the above - mentioned materials into the fully - automatic fifteen - tube furnace for dry - hydrogen reduction;

[0052] After dry - hydrogen reduction, perform screening to obtain ultra - coarse tungsten powder.

[0053] Example 3

[0054] The preparation method of the ultra - coarse tungsten powder provided in this example includes the following steps:

[0055] First, spread a layer of blue tungsten with a particle size of 30 - 35 μm in the boat, and then spread another layer of blue tungsten with a particle size of 2 - 5 μm. The mass ratio of the blue tungsten with a particle size of 30 - 35 μm to the blue tungsten with a particle size of 2 - 5 μm is 12:1, and the total thickness of the material layer (blue tungsten) in the boat is 3 cm;

[0056] Start the fifteen - tube furnace and set the parameters as follows: the flow rate of hydrogen (dry) is 5 m 3 / h, the temperature is 1200 °C, and the time is 6 h; Push the boat filled with the above - mentioned materials into the fully - automatic fifteen - tube furnace for dry - hydrogen reduction;

[0057] After dry - hydrogen reduction, perform screening to obtain ultra - coarse tungsten powder.

[0058] Example 4

[0059] The method for preparing ultra-coarse tungsten powder provided by this embodiment includes the following steps:

[0060] First, spread a layer of blue tungsten with a particle size of 30 - 35 μm in a boat, and then spread a layer of blue tungsten with a particle size of 2 - 5 μm on it. The mass ratio of the blue tungsten with a particle size of 30 - 35 μm to the blue tungsten with a particle size of 2 - 5 μm is 9:1, and the total thickness of the material layer (blue tungsten) in the boat is 2 cm;

[0061] Start the fifteen-tube furnace and set the parameters as follows: the flow rate of hydrogen (dry) is 5 m 3 / h, the temperature is 1200 °C, and the time is 6 h; push the boat filled with the above materials into the fully automatic fifteen-tube furnace for dry hydrogen reduction;

[0062] After dry hydrogen reduction, perform screening to obtain ultra-coarse tungsten powder.

[0063] Example 5

[0064] The method for preparing ultra-coarse tungsten powder provided by this embodiment includes the following steps:

[0065] First, spread a layer of blue tungsten with a particle size of 30 - 35 μm in a boat, and then spread a layer of blue tungsten with a particle size of 2 - 5 μm on it. The mass ratio of the blue tungsten with a particle size of 30 - 35 μm to the blue tungsten with a particle size of 2 - 5 μm is 9:1, and the total thickness of the material layer (blue tungsten) in the boat is 5 cm;

[0066] Start the fifteen-tube furnace and set the parameters as follows: the flow rate of hydrogen (dry) is 5 m 3 / h, the temperature is 1200 °C, and the time is 6 h; push the boat filled with the above materials into the fully automatic fifteen-tube furnace for dry hydrogen reduction;

[0067] After dry hydrogen reduction, perform screening to obtain ultra-coarse tungsten powder.

[0068] Example 6

[0069] The method for preparing ultra-coarse tungsten powder provided by this embodiment includes the following steps:

[0070] First, spread a layer of blue tungsten with a particle size of 30 - 35 μm in a boat, and then spread a layer of blue tungsten with a particle size of 2 - 5 μm on it. The mass ratio of the blue tungsten with a particle size of 30 - 35 μm to the blue tungsten with a particle size of 2 - 5 μm is 9:1, and the total thickness of the material layer (blue tungsten) in the boat is 3 cm;

[0071] Start the fifteen-tube furnace and set the parameters as follows: the flow rate of hydrogen (dry) is 7 m 3 / h, the temperature is 1300 °C, and the time is 8 h; push the boat filled with the above materials into the fully automatic fifteen-tube furnace for dry hydrogen reduction;

[0072] After dry hydrogen reduction, perform screening to obtain ultra-coarse tungsten powder.

[0073] Example 7

[0074] The method for preparing ultra - coarse tungsten powder provided in this example includes the following steps:

[0075] First, spread a layer of tungsten oxide with a particle size of 30 - 35 μm in the boat, and then spread a layer of tungsten oxide with a particle size of 2 - 5 μm on it. The mass ratio of the tungsten oxide with a particle size of 30 - 35 μm to the tungsten oxide with a particle size of 2 - 5 μm is 9:1, and the total thickness of the material layer (tungsten oxide) in the boat is 3 cm;

[0076] Start the fifteen - tube furnace and set the parameters as follows: the flow rate of hydrogen (dry) is 5m 3 / h, the temperature is 1200 °C, and the time is 6 h; push the boat filled with the above - mentioned materials into the fully automatic fifteen - tube furnace for dry - hydrogen reduction;

[0077] After dry - hydrogen reduction, perform screening to obtain ultra - coarse tungsten powder.

[0078] Example 8

[0079] The method for preparing ultra - coarse tungsten powder provided in this example includes the following steps:

[0080] First, spread a layer of blue tungsten with a particle size of 30 - 35 μm in the boat, and then spread a layer of blue tungsten with a particle size of 10 - 15 μm on it. The mass ratio of the blue tungsten with a particle size of 30 - 35 μm to the blue tungsten with a particle size of 10 - 15 μm is 12:1, and the total thickness of the material layer (blue tungsten) in the boat is 3 cm;

[0081] Start the fifteen - tube furnace and set the parameters as follows: the flow rate of hydrogen (dry) is 5m 3 / h, the temperature is 1200 °C, and the time is 6 h; push the boat filled with the above - mentioned materials into the fully automatic fifteen - tube furnace for dry - hydrogen reduction;

[0082] After dry - hydrogen reduction, perform screening to obtain ultra - coarse tungsten powder.

[0083] Example 9

[0084] The method for preparing ultra - coarse tungsten powder provided in this example includes the following steps:

[0085] First, spread a layer of blue tungsten with a particle size of 50 - 60 μm in the boat, and then spread a layer of blue tungsten with a particle size of 2 - 5 μm on it. The mass ratio of the blue tungsten with a particle size of 50 - 60 μm to the blue tungsten with a particle size of 2 - 5 μm is 12:1, and the total thickness of the material layer (blue tungsten) in the boat is 3 cm;

[0086] Start the fifteen - tube furnace and set the parameters as follows: the flow rate of hydrogen (dry) is 5m 3at 1200 °C for 6 h; Push the above-loaded boat into a fully automatic fifteen-tube furnace for dry hydrogen reduction;

[0087] After dry hydrogen reduction, screening is carried out to obtain ultra-coarse tungsten powder.

[0088] Comparative Example 1

[0089] The preparation method of ultra-coarse tungsten powder provided in this comparative example includes the following steps:

[0090] Mix blue tungsten with a particle size of 30 - 35 μm and blue tungsten with a particle size of 2 - 5 μm, then spread them evenly in a boat. The mass ratio of blue tungsten with a particle size of 30 - 35 μm to blue tungsten with a particle size of 2 - 5 μm is 9:1, and the total thickness of the material layer (blue tungsten) in the boat is 3 cm;

[0091] Turn on the fifteen-tube furnace and set the parameters as follows: the flow rate of hydrogen (dry) is 5 m 3 / h, the temperature is 1200 °C, and the time is 6 h; Push the above-loaded boat into a fully automatic fifteen-tube furnace for dry hydrogen reduction;

[0092] After dry hydrogen reduction, screening is carried out to obtain ultra-coarse tungsten powder.

[0093] Comparative Example 2

[0094] The preparation method of ultra-coarse tungsten powder provided in this comparative example includes the following steps:

[0095] Spread blue tungsten with a particle size of 30 - 35 μm in a boat, and the total thickness of the material layer (blue tungsten) in the boat is 3 cm;

[0096] Turn on the fifteen-tube furnace and set the parameters as follows: the flow rate of hydrogen (dry) is 5 m 3 / h, the temperature is 1200 °C, and the time is 6 h; Push the above-loaded boat into a fully automatic fifteen-tube furnace for dry hydrogen reduction;

[0097] After dry hydrogen reduction, screening is carried out to obtain ultra-coarse tungsten powder.

[0098] Test Example

[0099] The Fisher particle size, purity, and oxygen content of the ultra-coarse tungsten powder prepared in Examples 1 - 9 and Comparative Examples 1 - 2 are shown in Table 1.

[0100] Table 1

[0101]

[0102]

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing super-coarse tungsten powder, characterized in that It includes the following steps: Lay the second material layer on the first material layer, and after dry hydrogen reduction and screening in sequence, obtain the ultra-coarse tungsten powder; Among them, the first material layer includes tungsten-containing raw materials with a first particle size, the second material layer includes tungsten-containing raw materials with a second particle size, and the first particle size is greater than the second particle size.

2. The preparation method of the ultra-coarse tungsten powder according to claim 1, wherein, The tungsten-containing raw materials include blue tungsten and / or tungsten oxide.

3. The preparation method of the ultra-coarse tungsten powder according to claim 1, wherein, The first material layer includes tungsten-containing raw materials with a particle size of 30 - 35 μm, and the second material layer includes tungsten-containing raw materials with a particle size of 2 - 5 μm.

4. The method for preparing super-coarse tungsten powder according to claim 3, wherein The mass ratio of the tungsten-containing raw materials with a particle size of 30 - 35 μm to the tungsten-containing raw materials with a particle size of 2 - 5 μm is (8 - 12):

1.

5. The preparation method of the ultra-coarse tungsten powder according to claim 1, characterized in that, The total thickness of the second material layer and the first material layer is 2 - 5 cm.

6. The method for preparing super-coarse tungsten powder according to claim 1, wherein The hydrogen flow rate for the dry hydrogen reduction is 3 to 8 m 3 / h.

7. The preparation method of the ultra-coarse tungsten powder according to claim 1, wherein The temperature of the dry hydrogen reduction is 900 - 1400 °C.

8. The preparation method of the ultra-coarse tungsten powder according to claim 1, characterized in that, The time of the dry hydrogen reduction is 5 - 10 h.

9. The method for preparing super-coarse tungsten powder according to claim 1, wherein, The device for the dry hydrogen reduction includes a fifteen-tube furnace.

10. The preparation method of the ultra-coarse tungsten powder according to claim 1, characterized in that, The Fisher particle size of the ultra-coarse tungsten powder is 35 - 40 μm.

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