A needle-like purple tungsten and a preparation process thereof

Abstract

The present application belongs to the field of powder metallurgy, and particularly relates to a needle-like purple tungsten and a preparation process thereof. The needle-like purple tungsten is stably prepared by using ammonium paratungstate as raw material and controlling the calcination atmosphere and temperature zone in a rotary furnace. The problems of easy agglomeration of the material in the calcination process of the purple tungsten, thereby causing the blockage of the furnace tube, and easy air entering the furnace tail in the preparation process of the purple tungsten, thereby causing the oxidation of the material and the generation of yellow tungsten are solved. The BET of the prepared needle-like purple tungsten is greater than or equal to 3.45 m 2 / g, the oxygen index is stably 2.72-2.74, and the product quality is effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of powder metallurgy technology, specifically a needle-shaped purple tungsten and its preparation process. Background Technology

[0002] Ultrafine cemented carbide refers to cemented carbide materials with an average WC grain size of 0.2–0.5 μm. Compared to traditional WC-CO cemented carbide, ultrafine cemented carbide possesses both high strength and high hardness, meeting the machining needs of some difficult-to-machine materials in modern industry. It is one of the important research and development directions in the cemented carbide industry. Its main applications include machining difficult-to-cut materials such as high-temperature alloys, titanium alloys, and stainless steel; low-speed cutting and intermittent cutting tools; mining and rock drilling tools; and cemented carbide top hammers for synthetic diamond. It is also widely used in high-efficiency, high-precision cutting processes in industries such as automotive manufacturing, aerospace, mold manufacturing, and electronic information, especially in micro-drills for integrated circuit board processing.

[0003] The main raw material for producing ultrafine cemented carbide is ultrafine tungsten carbide powder. Studies have shown that tungsten carbide powder, due to its unique structure and excellent permeability, is the best raw material for preparing uniform ultrafine tungsten powder. Tungsten carbide mainly exists in two crystal forms: short, coarse rod-shaped and long, slender needle-shaped. The tungsten powder prepared from the long, slender needle-shaped crystal is finer and more uniform. Currently, industrial production of tungsten carbide primarily uses ammonium paratungstate (APT) as raw material, calcined in a rotary kiln. However, this method mainly produces short, coarse rod-shaped tungsten carbide and is prone to furnace blockage, severely affecting product quality. Summary of the Invention

[0004] To address the problems existing in the prior art, the main objective of this invention is to propose a needle-shaped purple tungsten and its preparation process, which makes the purple tungsten crystal form needle-shaped with a large aspect ratio, thereby reducing the production of short rod-shaped purple tungsten crystals.

[0005] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0006] A process for preparing needle-shaped purple tungsten includes the following steps:

[0007] S1. Ammonium paratungstate pretreatment;

[0008] S2. The pretreated ammonium paratungstate is fed into a rotary kiln for calcination. The temperature in the rotary kiln is set to three temperature zones from the feed end to the discharge end, with a temperature difference of 8 to 15°C, and all three temperature zones are within the temperature range of 650 to 800°C. Needle-shaped purple tungsten is obtained after exiting the kiln.

[0009] As a preferred embodiment of the preparation process of needle-shaped purple tungsten according to the present invention, in step S1, the ammonium paratungstate pretreatment is a sieve pretreatment of ammonium paratungstate.

[0010] As a preferred embodiment of the preparation process of needle-shaped purple tungsten according to the present invention, in step S1, the laser particle size D50 of the ammonium paratungstate after sieving pretreatment is 50-70 μm and the diameter is 1.0-1.5.

[0011] As a preferred embodiment of the preparation process of needle-shaped purple tungsten according to the present invention, in step S2, before the pretreated ammonium paratungstate is fed into the rotary kiln, nitrogen gas is introduced into the rotary kiln to discharge air and other gases in the furnace and reduce the interference of gases in the furnace.

[0012] In a preferred embodiment of the preparation process of needle-shaped purple tungsten according to the present invention, in step S2, when the pretreated ammonium paratungstate is fed into the rotary kiln, nitrogen gas is continuously introduced into the rotary kiln.

[0013] In a preferred embodiment of the preparation process of needle-shaped purple tungsten according to the present invention, in step S2, after the pretreated ammonium paratungstate is fed into the rotary kiln, the nitrogen flow rate is reduced, and ammonia gas is introduced simultaneously at a flow rate of 1.0–2.5 m³ / h. 3 / h, the ammonia to nitrogen flow ratio is 3:1.

[0014] As a preferred embodiment of the preparation process of needle-shaped purple tungsten according to the present invention, in step S2, the pretreated ammonium paratungstate is fed into the rotary kiln by a spiral feeding method, and the feeding speed is controlled to be 20-50 kg / h.

[0015] In a preferred embodiment of the preparation process of needle-shaped purple tungsten according to the present invention, in step S2, the rotation speed of the rotary kiln tube is 2-5 r / min.

[0016] As a preferred embodiment of the preparation process of needle-shaped purple tungsten according to the present invention, in step S2, the furnace is discharged by a spiral discharge method, and the discharge speed is controlled to be 10-40 kg / h.

[0017] To solve the above-mentioned technical problems, according to another aspect of the present invention, the present invention provides the following technical solution:

[0018] A needle-shaped purple tungsten, prepared using the above-described process, wherein the BET of the needle-shaped purple tungsten is ≥3.45m. 2 / g, with the oxygen index remaining stable at 2.72–2.74.

[0019] The beneficial effects of this invention are as follows:

[0020] This invention proposes a method for preparing needle-shaped tungsten and its preparation process. Using ammonium paratungstate as raw material, the calcination atmosphere and temperature are controlled in a rotary furnace, enabling stable preparation of needle-shaped tungsten. This method solves the problem of material agglomeration during tungsten calcination, which leads to furnace tube blockage. It also addresses the issue of air entering the furnace tail during tungsten preparation, causing material oxidation and the formation of yellow tungsten. The prepared needle-shaped tungsten has a BET ≥ 3.45m. 2 / g, with an oxygen index that remained stable at 2.72–2.74, effectively improving product quality. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0022] Figure 1 The image shows a SEM image of needle-shaped purple tungsten prepared in Example 1 of this invention.

[0023] Figure 2 This is a SEM image of the needle-shaped purple tungsten prepared in Example 2 of the present invention;

[0024] Figure 3 This is a SEM image of the needle-shaped purple tungsten prepared in Example 3 of the present invention;

[0025] Figure 4 This is a SEM image of the needle-shaped purple tungsten prepared in Example 4 of the present invention;

[0026] Figure 5 This is a SEM image of needle-shaped purple tungsten prepared in Example 5 of the present invention;

[0027] Figure 6 This is a SEM image of the needle-shaped purple tungsten prepared in Example 6 of the present invention;

[0028] Figure 7 This is a SEM image of the needle-shaped purple tungsten prepared in Example 7 of the present invention;

[0029] Figure 8 Here is a SEM image of purple tungsten prepared in Comparative Example 1 of this invention;

[0030] Figure 9 Here is a SEM image of the purple tungsten prepared in Comparative Example 2 of this invention;

[0031] Figure 10 Here is a SEM image of the purple tungsten prepared in Comparative Example 3 of this invention;

[0032] Figure 11 This is a SEM image of the purple tungsten prepared in Comparative Example 4 of this invention.

[0033] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0034] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] The main objective of this invention is to propose a needle-shaped tungsten crystal and its preparation process, which makes the tungsten crystal form needle-shaped with a large aspect ratio, thereby reducing the production of short rod-shaped tungsten crystals.

[0036] According to one aspect of the present invention, the present invention provides the following technical solution:

[0037] A process for preparing needle-shaped purple tungsten includes the following steps:

[0038] S1. Ammonium paratungstate pretreatment;

[0039] S2. The pretreated ammonium paratungstate is fed into a rotary kiln for calcination. The temperature in the rotary kiln is set to three temperature zones from the feed end to the discharge end, with a temperature difference of 8 to 15°C, and all three temperature zones are within the temperature range of 650 to 800°C. Needle-shaped purple tungsten is obtained after exiting the kiln.

[0040] Preferably, in step S1, the ammonium paratungstate pretreatment is a sieving pretreatment of the ammonium paratungstate; the laser particle size D50 of the pretreated ammonium paratungstate is 50-70 μm, and the span is 1.0-1.5; specifically, the laser particle size D50 of the ammonium paratungstate can be, for example, but not limited to, any one or any two of 50 μm, 55 μm, 60 μm, 65 μm, 70 μm; the span can be, for example, but not limited to, any one or any two of 1.0, 1.1, 1.2, 1.3, 1.4, 1.5.

[0041] Preferably, in step S2, the temperature inside the rotary kiln from the feed end to the discharge end is set into three temperature zones with a 10°C temperature difference, ranging from low to high; and all three temperature zones are within the temperature range of 680 to 750°C. The influence of temperature on crystal form is mainly manifested as follows: if the temperature is too low, ammonium paratungstate cannot be completely calcined, and some of the ammonium paratungstate morphology will be retained, affecting the performance of purple tungsten; if the temperature is too high, the needle-shaped purple tungsten will easily break, forming short rod-shaped purple tungsten. By setting the temperature from the feed end to the discharge end into three temperature zones with a 10°C temperature difference, the high temperature can be blown to the front section by the airflow at the tail of the furnace, saving energy consumption.

[0042] More preferably, in step S2, before the pretreated ammonium paratungstate is fed into the rotary kiln, nitrogen gas is introduced into the rotary kiln to expel air and other gases inside the kiln and reduce interference from gases inside the kiln; when the pretreated ammonium paratungstate is fed into the rotary kiln, nitrogen gas is continuously introduced into the rotary kiln; after the pretreated ammonium paratungstate is fed into the rotary kiln, the nitrogen gas flow rate is reduced, and ammonia gas is introduced simultaneously, with an ammonia gas flow rate of 1.0–2.5 m³ / h. 3 The ammonia to nitrogen flow rate is 3:1 per hour. Specifically, the ammonia flow rate can be, for example, but not limited to, 1.0 m³ / h. 3 / h, 1.5m 3 / h, 2.0m 3 / h, 2.5m 3 The range of any one or any two of / h; ammonia is a reducing atmosphere that decomposes into hydrogen and nitrogen when heated; the main function of nitrogen is to vent other gases in the furnace and quickly remove the moisture produced by APT calcination, so as to avoid the problem of material agglomeration caused by excessive humidity in the furnace, which would lead to furnace tube blockage.

[0043] More preferably, in step S2, the pretreated ammonium paratungstate is fed into the rotary kiln using a screw feeder to ensure that the material can enter the rotary kiln evenly, and the feeding speed is controlled to be 20-50 kg / h; specifically, the feeding speed can be, for example, but not limited to, any one or any two of 20 kg / h, 25 kg / h, 30 kg / h, 35 kg / h, 40 kg / h, 45 kg / h, and 50 kg / h.

[0044] More preferably, the rotary kiln tube rotation speed is 2 to 5 r / min, specifically, the rotary kiln tube rotation speed is any one of 2 r / min, 3 r / min, 4 r / min, and 5 r / min or a range between any two of them;

[0045] Preferably, in step S2, the material is discharged from the furnace using a screw conveyor, and the discharge speed is controlled to be 10–40 kg / h. Specifically, the discharge speed can be, for example, but not limited to, any one or any two of 10 kg / h, 15 kg / h, 20 kg / h, 25 kg / h, 30 kg / h, 35 kg / h, and 40 kg / h.

[0046] According to another aspect of the present invention, the present invention provides the following technical solution:

[0047] A needle-shaped purple tungsten was prepared using the above-described preparation process.

[0048] Preferably, the BET of the needle-shaped purple tungsten is ≥3.45m. 2 / g, with the oxygen index remaining stable at 2.72–2.74.

[0049] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0050] Example 1

[0051] A process for preparing needle-shaped purple tungsten includes the following steps:

[0052] S1. Ammonium paratungstate pretreatment;

[0053] The raw material ammonium paratungstate was sieved using a vibrating screen with a mesh size of 120 mesh. Ammonium paratungstate with a laser particle size D50 of 55 μm and a diameter of 1.3 was selected.

[0054] S2. The pretreated ammonium paratungstate is fed into a rotary kiln for calcination using a screw feeder. The feed rate is controlled at 30 kg / h, and the furnace tube rotation speed is 3 r / min. The temperature inside the rotary kiln from the feed end to the discharge end is set to three temperature zones from low to high: 680℃, 690℃, and 700℃. The nitrogen flow rate is 0.4 m³ / h. 3 / h, ammonia flow rate is 1.2m 3 / h; using a discharge speed of 25kg / h for spiral discharge to obtain needle-shaped purple tungsten (such as Figure 1 As shown), by Figure 1 It can be seen that the acicular purple tungsten prepared in this embodiment exhibits a acicular crystal form, with a BET of 3.5m. 2 / g, oxygen index is 2.72, no yellow tungsten oxide.

[0055] Example 2

[0056] A process for preparing needle-shaped purple tungsten includes the following steps:

[0057] S1. Ammonium paratungstate pretreatment;

[0058] The raw material ammonium paratungstate was sieved using a vibrating screen with a mesh size of 120 mesh. Ammonium paratungstate with a laser particle size D50 of 52 μm and a diameter of 1.4 was selected.

[0059] S2. The pretreated ammonium paratungstate is fed into a rotary kiln for calcination using a screw feeder. The feed rate is controlled at 20 kg / h, and the furnace tube rotation speed is 2 r / min. The temperature inside the rotary kiln from the feed end to the discharge end is set to three temperature zones from low to high: 700℃, 710℃, and 720℃. The nitrogen flow rate is 0.3 m³ / h. 3 / h, ammonia flow rate is 0.9m 3 / h; using a discharge speed of 15kg / h for spiral discharge to obtain needle-shaped purple tungsten (such as Figure 2 As shown), by Figure 2It can be seen that the acicular purple tungsten prepared in this embodiment exhibits a acicular crystal form, with a BET of 3.45m. 2 / g, oxygen index is 2.72, no yellow tungsten oxide.

[0060] Example 3

[0061] A process for preparing needle-shaped purple tungsten includes the following steps:

[0062] S1. Ammonium paratungstate pretreatment;

[0063] The raw material ammonium paratungstate was sieved using a vibrating screen with a mesh size of 120 mesh. Ammonium paratungstate with a laser particle size D50 of 61 μm and a diameter of 1.1 was selected.

[0064] S2. The pretreated ammonium paratungstate is fed into a rotary kiln for calcination using a screw feeder. The feed rate is controlled at 20 kg / h, and the furnace tube speed is 5 r / min. The temperature inside the rotary kiln from the feed end to the discharge end is set to three temperature zones from low to high: 720℃, 730℃, and 740℃. The nitrogen flow rate is 0.4 m³ / h. 3 / h, ammonia flow rate is 1.2m 3 / h; using a discharge speed of 15kg / h for spiral discharge to obtain needle-shaped purple tungsten (such as Figure 3 As shown), by Figure 3 It can be seen that the acicular purple tungsten prepared in this embodiment exhibits a acicular crystal form, with a BET of 3.53m. 2 / g, oxygen index is 2.73, no yellow tungsten oxide.

[0065] Example 4

[0066] A process for preparing needle-shaped purple tungsten includes the following steps:

[0067] S1. Ammonium paratungstate pretreatment;

[0068] The raw material ammonium paratungstate was sieved using a vibrating screen with a mesh size of 120 mesh. Ammonium paratungstate with a laser particle size D50 of 58 μm and a diameter of 1.3 was selected.

[0069] S2. The pretreated ammonium paratungstate is fed into a rotary kiln for calcination using a screw feeder. The feed rate is controlled at 30 kg / h, and the furnace tube rotation speed is 3 r / min. The temperature inside the rotary kiln from the feed end to the discharge end is set to three temperature zones from low to high: 700℃, 710℃, and 720℃. The nitrogen flow rate is 0.5 m³ / h. 3 / h, ammonia flow rate is 1.5m 3 / h; using a discharge speed of 25kg / h for spiral discharge to obtain needle-shaped purple tungsten (such as Figure 4 As shown), by Figure 4It can be seen that the acicular purple tungsten prepared in this embodiment exhibits a acicular crystal form, with a BET of 3.50m. 2 / g, oxygen index is 2.73, no yellow tungsten oxide.

[0070] Example 5

[0071] A process for preparing needle-shaped purple tungsten includes the following steps:

[0072] S1. Ammonium paratungstate pretreatment;

[0073] The raw material ammonium paratungstate was sieved using a vibrating screen with a mesh size of 120 mesh. Ammonium paratungstate with a laser particle size D50 of 55 μm and a diameter of 1.5 was selected.

[0074] S2. The pretreated ammonium paratungstate is fed into a rotary kiln for calcination using a screw feeder. The feed rate is controlled at 40 kg / h, and the furnace tube rotation speed is 3 r / min. The temperature inside the rotary kiln from the feed end to the discharge end is set to three temperature zones from low to high: 700℃, 710℃, and 720℃. The nitrogen flow rate is 0.4 m³ / h. 3 / h, ammonia flow rate is 1.2m 3 / h; using a discharge speed of 35kg / h for spiral discharge to obtain needle-shaped purple tungsten (such as Figure 5 As shown), by Figure 5 It can be seen that the acicular purple tungsten prepared in this embodiment exhibits a acicular crystal form, with a BET of 3.60m. 2 / g, oxygen index is 2.74, no yellow tungsten oxide.

[0075] Example 6

[0076] A process for preparing needle-shaped purple tungsten includes the following steps:

[0077] S1. Ammonium paratungstate pretreatment;

[0078] The raw material ammonium paratungstate was sieved using a vibrating screen with a mesh size of 120 mesh. Ammonium paratungstate with a laser particle size D50 of 65 μm and a diameter of 1.2 was selected.

[0079] S2. The pretreated ammonium paratungstate is fed into a rotary kiln for calcination using a screw feeder. The feed rate is controlled at 30 kg / h, and the furnace tube rotation speed is 3 r / min. The temperature inside the rotary kiln from the feed end to the discharge end is set to three temperature zones from low to high: 680℃, 690℃, and 700℃. The nitrogen flow rate is 0.4 m³ / h. 3 / h, ammonia flow rate is 1.2m 3 / h; using a discharge speed of 25kg / h for spiral discharge to obtain needle-shaped purple tungsten (such as Figure 6 As shown), by Figure 6It can be seen that the acicular purple tungsten prepared in this embodiment exhibits a acicular crystal form, with a BET of 3.45m. 2 / g, oxygen index is 2.72, no yellow tungsten oxide.

[0080] Example 7

[0081] A process for preparing needle-shaped purple tungsten includes the following steps:

[0082] S1. Ammonium paratungstate pretreatment;

[0083] The raw material ammonium paratungstate was sieved using a vibrating screen with a mesh size of 120 mesh. Ammonium paratungstate with a laser particle size D50 of 56 μm and a diameter of 1.5 was selected.

[0084] S2. The pretreated ammonium paratungstate is fed into a rotary kiln for calcination using a screw feeder. The feed rate is controlled at 30 kg / h, and the furnace tube rotation speed is 3 r / min. The temperature inside the rotary kiln from the feed end to the discharge end is set to three temperature zones from low to high: 680℃, 690℃, and 700℃. The nitrogen flow rate is 0.6 m³ / h. 3 / h, ammonia flow rate is 1.8m 3 / h; using a discharge speed of 25kg / h for spiral discharge to obtain needle-shaped purple tungsten (such as Figure 7 As shown), by Figure 7 It can be seen that the acicular purple tungsten prepared in this embodiment exhibits a acicular crystal form, with a BET of 3.63m. 2 / g, oxygen index is 2.72, no yellow tungsten oxide.

[0085] Comparative Example 1

[0086] A process for preparing purple tungsten includes the following steps:

[0087] S1. Ammonium paratungstate pretreatment;

[0088] The raw material ammonium paratungstate was sieved using a vibrating screen with a mesh size of 120 mesh. Ammonium paratungstate with a laser particle size D50 of 66 μm and a diameter of 1.4 was selected.

[0089] S2. The pretreated ammonium paratungstate is fed into a rotary kiln for calcination using a screw feeder. The feed rate is controlled at 40 kg / h, and the furnace tube rotation speed is 3 r / min. The temperature inside the rotary kiln from the feed end to the discharge end is set to three temperature zones from low to high: 750℃, 760℃, and 770℃. The nitrogen flow rate is 0.4 m³ / h. 3 / h, ammonia flow rate is 0.8m 3 / h; using a discharge speed of 35kg / h for spiral discharge to obtain purple tungsten (such as Figure 8 As shown), by Figure 8It can be seen that the tungsten crystals prepared in this comparative example exhibit a mixture of needle-like and rod-like crystals, with a BET value of 3.13m. 2 / g, oxygen index is 2.78, no yellow tungsten oxide.

[0090] Comparative Example 2

[0091] A process for preparing purple tungsten includes the following steps:

[0092] S1. Ammonium paratungstate pretreatment;

[0093] The raw material ammonium paratungstate was sieved using a vibrating screen with a mesh size of 120 mesh. Ammonium paratungstate with a laser particle size D50 of 54 μm and a diameter of 1.2 was selected.

[0094] S2. The pretreated ammonium paratungstate is fed into a rotary kiln for calcination using a screw feeder. The feed rate is controlled at 40 kg / h, and the furnace tube rotation speed is 2 r / min. The temperature inside the rotary kiln from the feed end to the discharge end is set to three temperature zones from low to high: 630℃, 640℃, and 650℃. The nitrogen flow rate is 0.5 m³ / h. 3 / h, ammonia flow rate is 0.5m³ / h. 3 / h; using a discharge speed of 35kg / h for spiral discharge to obtain purple tungsten (such as Figure 9 As shown), by Figure 9 It can be seen that the tungsten crystal structure prepared in this comparative example is incompletely reduced, with a BET of 2.5m. 2 / g, oxygen index is 2.92, no yellow tungsten oxide.

[0095] Comparative Example 3

[0096] A process for preparing purple tungsten includes the following steps:

[0097] Unsieved ammonium paratungstate was fed into a rotary kiln for calcination using a screw feeder. The feed rate was controlled at 30 kg / h, and the furnace tube rotation speed was 8 r / min. The temperature inside the rotary kiln, from the feed end to the discharge end, was set into three temperature zones: 700℃, 710℃, and 720℃, increasing from low to high. The nitrogen flow rate was 0.8 m³ / h. 3 / h, ammonia flow rate is 0.4m³ / h. 3 / h; using a discharge speed of 25kg / h for spiral discharge to obtain purple tungsten (such as Figure 10 As shown), by Figure 10 It can be seen that the purple tungsten prepared in this comparative example exhibits a rod-like crystal structure, with a BET of 2.9 m. 2 / g, oxygen index is 2.82, no yellow tungsten oxide.

[0098] Comparative Example 4

[0099] A process for preparing purple tungsten includes the following steps:

[0100] Unsieved ammonium paratungstate was fed into a rotary kiln for calcination using a screw feeder. The feed rate was controlled at 40 kg / h, and the furnace tube rotation speed was 5 r / min. The temperature inside the rotary kiln, from the feed end to the discharge end, was set into three temperature zones: 750℃, 760℃, and 770℃, increasing from low to high. The nitrogen flow rate was 1.0 m³ / h. 3 / h, ammonia flow rate is 0.5m³ / h. 3 / h; using a discharge speed of 35kg / h for spiral discharge to obtain purple tungsten (such as Figure 11 As shown), by Figure 11 It can be seen that the purple tungsten prepared in this comparative example exhibits a rod-like crystal structure, with a BET of 3.2 m. 2 / g, oxygen index is 2.76, no yellow tungsten oxide.

[0101] This invention uses ammonium paratungstate as raw material and controls the calcination atmosphere and temperature in a rotary furnace to stably prepare needle-shaped purple tungsten. It solves the problem of material agglomeration during purple tungsten calcination, which leads to furnace tube blockage, and also addresses the issue of air entering the furnace tail during purple tungsten preparation, causing material oxidation and the formation of yellow tungsten. The prepared needle-shaped purple tungsten has a BET ≥ 3.45m. 2 / g, with an oxygen index that remained stable at 2.72–2.74, effectively improving product quality.

[0102] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A process for preparing needle-shaped purple tungsten, characterized in that, Includes the following steps: S1. Ammonium paratungstate pretreatment, the laser particle size D50 of the pretreated ammonium paratungstate is 60~70μm, and the diameter is 1.0~1.5; S2. Pretreated ammonium paratungstate is fed into a rotary kiln for calcination using a screw feeder, with the feed rate controlled at 20-50 kg / h and the kiln tube speed at 2-5 r / min. The ammonium paratungstate is discharged from the kiln using a screw discharger, with the discharge rate controlled at 10-40 kg / h. Nitrogen gas is continuously introduced into the rotary kiln while the pretreated ammonium paratungstate is fed in. After the pretreated ammonium paratungstate is fed into the rotary kiln, the nitrogen flow rate is reduced, and ammonia gas is introduced simultaneously at a flow rate of 2.0-2.5 m³ / h. 3 The ammonia to nitrogen flow rate ratio is 3:1; the temperature inside the rotary kiln is set to three temperature zones from the feed end to the discharge end, with a temperature difference of 8~15℃, and all three temperature zones are within the temperature range of 650~720℃; needle-shaped tungsten is obtained after exiting the kiln, and the BET of the needle-shaped tungsten is ≥3.45m. 2 / g, with an oxygen index of 2.72~2.

74.

2. The preparation process according to claim 1, characterized in that, In step S1, the ammonium paratungstate pretreatment is a screening pretreatment of the ammonium paratungstate.

3. The preparation process according to claim 1, characterized in that, In step S2, before the pretreated ammonium paratungstate is fed into the rotary kiln, nitrogen gas is introduced into the rotary kiln to expel air and other gases from the kiln and reduce interference from the gases inside the kiln.

4. A needle-shaped purple tungsten, prepared using any one of the preparation processes according to claims 1-3.

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