Amorphous tungstic acid fused body and tungsten oxide manufactured by using the same

Abstract

To provide an amorphous tungstic acid fused body formed by aggregating primary particles of tungstic acid.SOLUTION: The present invention relates to an amorphous tungstic acid fused body formed by aggregating tungstic acid primary particles. The amorphous tungstic acid fused body provided herein is an amorphous tungstic acid fused body characterized by forming a bunch-like structure by interconnection of the tungstic acid primary particles to each other. According to one embodiment of the present invention, an environmentally-friendly, low-cost process technique is provided in which atmosphere and water pollution emission matters are greatly reduced while a process cost is decreased by not proceeding with an APT step.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a tungstic acid fusion produced by a wet process, and a tungsten oxide and a tungsten powder produced using the same, and more particularly, to a tungstic acid fusion shaped by a wet process. [Background technology]

[0002] Due to the development of high-tech industries, the development of the quaternary industry, and increased demand for the environment, tungsten usage is increasing in the tool and mold sector, which is the largest consumer of tungsten, and tungsten usage is also rapidly increasing in the semiconductor specialty gases, SCR catalysts, rolling parts, vibration motors, aerospace parts, thin films, functional ceramics, and other sectors.

[0003] The majority of the rapidly increasing demand for tungsten is from tungsten compounds (WF6gas, cermet, etc.) and composite materials containing tungsten (SCR catalysts, vibration motors, etc.), and the reality is that tungsten recycling technology is becoming increasingly difficult.

[0004] The most commonly used tungsten materials include tungsten oxide (WO3), tungsten powder (W) and tungsten carbide powder (WC).

[0005] There are two types of tungsten recycling technologies that have been developed so far: dry and wet. The dry method mainly produces WC from tungsten tools through multiple heat treatment steps, but it is difficult to apply to waste materials that contain impurities, and it is difficult to control the purity and particle size of the recycled WC.

[0006] On the other hand, the wet process uses ammonium paratungstate (APT: (NH4) 10 W 12 O 41The APT manufacturing process involves the use of ammonia to form and crystallize tungsten compounds, and in order to discharge the ammonia gas generated during this process, treatment facilities must be constructed to meet air quality standards. This creates a problem of significantly increasing the manufacturing costs of tungsten materials.

[0007] Therefore, the inventors introduced a new process that can replace the APT process, which is a limitation of the wet method, and produced high-purity amorphous tungstic acid (H2WO4) that can be used as a raw material for various tungsten materials, which led to the present invention. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been devised to solve the above problems, and one embodiment of the present invention provides an amorphous tungstic acid fusion formed by agglomerating primary particles of tungstic acid.

[0009] In another embodiment of the present invention, there is provided a tungsten oxide prepared by calcining powder of amorphous tungstic acid fusion.

[0010] In addition, another embodiment of the present invention provides a tungsten powder prepared by reducing an amorphous tungsten acid fusion powder.

[0011] In another embodiment of the present invention, there is provided a tungsten carbide powder produced by carburizing powder of amorphous tungsten acid fusion.

[0012] However, the technical problems that the present invention aims to achieve are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those having ordinary skill in the art to which the present invention pertains from the description below. [Means for solving the problem]

[0013] As a technical means for achieving the above technical object, one aspect of the present invention relates to an amorphous tungstic acid fusion formed by agglomerating primary particles of tungstic acid, and the amorphous tungstic acid fusion is characterized in that the primary particles of tungstic acid are interconnected to form a cluster-like structure.

[0014] The shape of the primary particles of tungstic acid may be characterized as being spherical, acicular, or a combination thereof.

[0015] The primary particles of tungstic acid may be characterized as being spherical particles having a diameter of 0.01 to 2.0 μm.

[0016] The primary particles of tungstic acid may be characterized as acicular particles having a length (L) of 0.01 to 1.8 μm and an aspect ratio (L / D) of 12 to 24.

[0017] The amorphous tungstic acid fusion bodies may be characterized as having a diameter of 30 μm or less.

[0018] D according to the particle size distribution of the amorphous tungstic acid fusion obtained by measuring by a laser diffraction scattering type particle size distribution measurement method 50 may be characterized as being between 5 and 12 μm.

[0019] The amorphous tungstic acid fusion bodies may be characterized by a standard deviation in diameter of 1.5 to 7 μm.

[0020] At least 80% of the tungstic acid primary particles may be characterized in that at least five of the tungstic acid primary particles are fused and bonded to each other to form an aggregate.

[0021] The tungstic acid primary particles may be composed of acicular particles and spherical particles, and the tungstic acid primary particles may be characterized in that the ratio of (weight of acicular particles):(weight of spherical particles) is 1:0.3 to 3.

[0022] Another aspect of the present invention provides a method for producing an amorphous tungstic acid fusion, the method including the steps of: adding a first additive including an ammonium compound to a tungstate aqueous solution; introducing an acidic solution into the tungstate aqueous solution; and adding a second additive including at least one of hydrogen peroxide and hydrofluoric acid to the aqueous solution after introducing the acidic solution; wherein the specific gravity of the tungstate aqueous solution is greater than 1.01 and less than 1.50, the acidic solution is introduced in an amount of 20 to 80 ml per 100 ml of the tungstate aqueous solution, the first additive is added in an amount of 1 to 10 g per 100 ml of the tungstate aqueous solution, and the second additive is added in an amount of 1 to 20 ml per 100 ml of the tungstate aqueous solution, the amorphous tungstic acid fusion is formed by interconnecting primary particles of tungstic acid to form a bunch-like structure, and the shape of the primary particles of tungstic acid is spherical, acicular, or a combination thereof.

[0023] The shape of the primary particles of the tungstic acid may be characterized as acicular or a combination of acicular and spherical shapes.

[0024] Another aspect of the present invention provides a tungsten oxide prepared by calcining the powder of the amorphous tungstic acid fusion.

[0025] Another aspect of the present invention provides a tungsten powder prepared by reducing the amorphous tungsten acid fusion powder.

[0026] Another aspect of the present invention provides a tungsten carbide powder prepared by carburizing the amorphous tungsten acid fusion powder. Effect of the Invention

[0027] According to one embodiment of the present invention, it is possible to provide an environmentally friendly, low-cost process technology that reduces process costs by not performing the APT process and significantly reduces air and water pollutant emissions.

[0028] In addition, according to an embodiment of the present invention, since it does not require the development of special equipment and devices, it is possible to provide a manufacturing process for tungsten material that is easily commercialized.

[0029] The effects of the present invention are not limited to the above effects, but should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the present invention or the claims. [Brief description of the drawings]

[0030] [Figure 1] 1 is a flow chart showing a method for preparing an amorphous tungstic acid fusion material according to an embodiment of the present invention; [Diagram 2] 2 is a flow chart showing in more detail the steps of a method for producing an amorphous tungstic acid fusion material according to an embodiment of the present invention in a time sequence. FIG. [Diagram 3] 1 shows a comparison of an SEM image of a conventional tungstic acid powder (left) and an SEM image of a tungstic acid fused powder according to an embodiment of the present invention (right). [Figure 4] 1 shows an SEM image of an example of a tungstic acid fusion prepared according to an embodiment of the present invention. [Diagram 5] 1 shows an SEM image of an example of a tungstic acid fusion prepared according to an embodiment of the present invention. [Figure 6] 1 shows an SEM image of an example of a tungstic acid fusion prepared according to an embodiment of the present invention. [Figure 7]1 shows XRD peak results of an example of a tungstic acid fusion prepared according to an embodiment of the present invention. [Figure 8] 1 shows XRD peak results of an example of a tungstic acid fusion prepared according to an embodiment of the present invention. [Figure 9] 1 shows XRD peak results of an example of a tungstic acid fusion prepared according to an embodiment of the present invention. [Figure 10] 1 shows a particle size distribution analysis result of an example of a tungstic acid fusion prepared according to an embodiment of the present invention. [Figure 11] 1 shows a particle size distribution analysis result of an example of a tungstic acid fusion prepared according to an embodiment of the present invention. [Figure 12] 1 shows a particle size distribution analysis result of an example of a tungstic acid fusion prepared according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather as defined by the claims set forth below.

[0032] In addition, the terms used in the present invention are merely used to describe specific embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless otherwise clearly intended in the context. Throughout the specification of the present invention, "comprises" a certain component does not exclude other components, but means that other components may be further included, unless otherwise specified to the contrary.

[0033] The first aspect of the present application is

[0034] Provided is an amorphous tungstic acid fusion formed by agglomerating primary particles of tungstic acid, characterized in that the primary particles of tungstic acid are interconnected to form a cluster-like structure.

[0035] The amorphous tungstic acid fusion material according to the first aspect of the present application will be described in detail below.

[0036] In one embodiment of the present application, the amorphous tungstic acid fusions may be interconnected between the tungstic acid primary particles to form a cluster structure, and the shape of the tungstic acid primary particles may be spherical, acicular, or a combination thereof.

[0037] In one embodiment of the present application, when the shape of the primary particles of tungstic acid is spherical, the primary particles may exist independently and be connected to each other to form a grape-like tungstic acid fusion. In one embodiment of the present application, the primary particles of tungstic acid may be spherical particles having a diameter of 0.01 to 2.0 μm. Preferably, the primary particles of tungstic acid may have a diameter of 0.03 to 1.8 μm, and the diameter of the primary particles of tungstic acid may vary depending on the process conditions. If the diameter exceeds 2.0 μm, the powder particles may become unnecessarily thick when the amorphous tungstic acid fusion is manufactured into tungsten oxide, tungsten, or tungsten carbide through a post-process, and if the diameter is less than 0.01 μm, the cluster structure is not observed and aggregation occurs more frequently.

[0038] In one embodiment of the present application, when the shape of the primary particles of tungstic acid is needle-shaped, the primary particles of tungstic acid may be needle-shaped particles having a length (L) of 0.01 to 1.8 μm and an aspect ratio (L / D) of 12 to 24. Preferably, the primary particles of tungstic acid may have a length (L) of 0.1 to 1.5 μm and an aspect ratio of 15 to 20. When the primary particles of tungstic acid have a length (L) of 0.01 to 1.8 μm and an aspect ratio of 12 to 24, the shape of the tungstic acid fusion may have a regular cluster structure compared to conventional amorphous tungstic acid powder. In the case of the tungstic acid fusion prepared according to one embodiment of the present application, when it is composed of only needle-shaped primary particles, it may have a relatively well-crystallized and interconnected and spread shape.

[0039] In one embodiment of the present application, the shape of the primary particles of tungstic acid may be a combination of spherical and acicular. In this case, the diameter of the primary particles of spherical tungstic acid may satisfy the above-mentioned range, and the length (L) and area ratio value of the primary particles of acicular tungstic acid may also satisfy the above-mentioned range. In one embodiment of the present application, the tungstic acid primary particles may be characterized by a ratio of (weight of acicular particles):(weight of spherical particles) of 1:0.3 to 3, preferably 1:0.8 to 2. By satisfying the above-mentioned range, it should be possible to obtain tungstic acid fusion particles with a properly controlled crystallinity. In the case of the tungstic acid fusion prepared according to one embodiment of the present application, the crystallinity may be lower than that of the tungstic acid fusion consisting of only acicular structures, but may be higher than that of the tungstic acid fusion consisting of only spherical primary particles, and may have a shape in which spherical and acicular shaped particles are mixed and interconnected to spread out.

[0040] In one embodiment of the present application, at least 50% of the tungstic acid primary particles may be characterized by at least three particles fused together and agglomerated. Preferably, at least 80% of the tungstic acid primary particles may be characterized by at least five particles fused together. By satisfying the above range, each primary particle can exist independently and form a tungstic acid fusion having a bunch-like structure like a bunch of grapes.

[0041] In one embodiment of the present application, the amorphous tungstic acid fusion particle characteristics can be measured by X-ray diffraction (XRD). The type, crystallinity, and distribution of crystal grains of the tungstic acid fusion can be analyzed through data such as peak position, area, intensity, and full width at half maximum (FWHM). The "amorphous tungstic acid fusion" includes all tungstic acid fusions with relatively low crystallinity, and as described below, the shape of the tungstic acid primary particles formed by the manufacturing method according to one embodiment of the present application can be adjusted to adjust the crystallinity.

[0042] In one embodiment of the present application, the diameter of the amorphous tungstic acid fusion may be 30 μm or less, preferably 25 μm. As will be described in detail below, in the case of the tungstic acid fusion according to one embodiment of the present application, the APT process is omitted, and a first additive containing an ammonium compound and a second additive containing at least one of hydrogen peroxide and hydrofluoric acid are added before and after the acidic solution is added to the tungstate aqueous solution, thereby producing a tungstic acid fusion having a regular particle shape and a particle size that can be appropriately controlled.

[0043] D according to the particle size distribution of the amorphous tungstic acid fusion obtained by measuring by a laser diffraction scattering type particle size distribution measurement method 50is preferably 5 to 16 μm, more preferably 5 to 12 μm. More preferably, when the shape of the tungstic acid primary particles is spherical, the D of the amorphous tungstic acid fusion 50 may be 7 to 10 μm, and when the shape of the tungstic acid primary particle is acicular, the D 50 may be 8.5 to 14 μm, and when the shape of the tungstic acid primary particles is a combination of acicular and spherical, the D 50 may be 6.5 to 9 μm.

[0044] In one embodiment of the present application, the standard deviation of the diameter of the amorphous tungstic acid fusion may be 1.5 to 7 μm, preferably 1.5 to 6.5 μm. This may vary depending on the shape of the tungstic acid primary particles, but preferably, when the shape of the tungstic acid primary particles is spherical, the standard deviation of the diameter of the amorphous tungstic acid fusion may be 2 to 4 μm, when the shape of the tungstic acid primary particles is acicular, the standard deviation of the diameter of the amorphous tungstic acid fusion may be 4 to 7 μm, and when the shape of the tungstic acid primary particles is a combination of acicular and spherical, the standard deviation of the diameter of the amorphous tungstic acid fusion may be 2 to 4 μm. When the standard deviation of the diameter of the amorphous tungstic acid fusion exceeds 7 μm, it is difficult to consider that the amorphous tungstic acid fusion was produced by a process in which the shape or particle size was appropriately controlled. When tungsten oxide, tungsten, or tungsten carbide is produced through a post-process, the particle size variation becomes even larger, making it difficult to produce a uniform powder.

[0045] A second aspect of the present application is

[0046] The present invention provides a method for producing an amorphous tungstic acid fusion, the method comprising the steps of: adding a first additive containing an ammonium compound to a tungstate aqueous solution; introducing an acidic solution into the tungstate aqueous solution; and adding a second additive containing at least one of hydrogen peroxide and hydrofluoric acid to the aqueous solution after introducing the acidic solution; wherein the specific gravity of the tungstate aqueous solution is greater than 1.01 and less than 1.50, the acidic solution is introduced in an amount of 20-80 ml per 100 ml of the tungstate aqueous solution, the first additive is added in an amount of 1-10 g per 100 ml of the tungstate aqueous solution, and the second additive is added in an amount of 1-20 ml per 100 ml of the tungstate aqueous solution, the amorphous tungstic acid fusion is formed by interconnecting primary particles of tungstic acid to form a bunch-like structure, and the shape of the primary particles of tungstic acid is spherical, acicular, or a combination thereof.

[0047] Detailed descriptions of parts that overlap with the first aspect of the present application have been omitted, but the contents described in the first aspect of the present application may be equally applied even if the description is omitted in the second aspect.

[0048] Hereinafter, a method for producing an amorphous tungstic acid fusion according to a second aspect of the present application will be described in detail with reference to the accompanying drawings.

[0049] FIG. 1 is a flow chart showing a method for preparing an amorphous tungstic acid fusion material according to an embodiment of the present invention.

[0050] As shown in FIG. 1, the method for producing tungsten oxide includes the steps of providing a tungstate aqueous solution (S110) and precipitating tungstic acid from the tungstate aqueous solution (S120).

[0051] The method for producing an amorphous tungstic acid fusion according to the embodiment of the present invention can be considered as a wet process since tungstic acid (H2WO4) is precipitated from a tungstate aqueous solution. When producing tungsten oxide by a wet process, a process for producing ammonium paratungstate (APT) is usually included, but according to the embodiment of the present invention, the APT production process can be omitted. When the APT production process is included, various disadvantages are caused by the characteristics of the production process. In particular, since the APT production process uses ammonia to form a tungsten compound and crystallize it, the evaporation / concentration process performed in the determination step requires a lot of energy and generates a large amount of ammonia gas. A lot of costs are incurred in the treatment of ammonia gas, making domestic tungsten production even more difficult. The reason why the APT production process is necessary despite the high costs is that tungstic acid powder forms fine and imperfectly shaped particles in the process of replacing tungstate with tungstic acid. The tungstic acid particles formed in the replacement process become more finely broken as they undergo the subsequent repeated washing processes, and the finer and more irregular the size of the tungstic acid particles, the more difficult the subsequent filtering and washing processes become. Here, the APT manufacturing process can increase the size of the tungstic acid particles and make their shape uniform, making it possible to easily handle the tungstic acid particles in the subsequent processes including the filtering and washing processes.

[0052] In one embodiment of the present application, the method for producing an amorphous tungstic acid fusion uses an additive in the process of replacing tungstate with tungstic acid to control the size and shape of the particles formed. The size of the particles can be as large as the tungstic acid particles produced by the APT production process, and the particle shape is not easily broken even in repeated water washing processes, and it is seen that the primary particles of tungstic acid are interconnected to form a cluster structure.

[0053] In one embodiment of the present application, the additive may be a first additive of an ammonium compound and a second additive containing at least one of hydrogen peroxide and hydrofluoric acid. By using the above additive in the substitution process, the precipitated tungstic acid powder is dissolved, aggregated, and dispersed, thereby forming particles of a uniform shape of a certain size or more, and the process efficiency of the subsequent filtration and water washing steps can be improved.

[0054] This will be considered in more detail below with reference to FIG.

[0055] FIG. 2 is a flow chart showing steps S110 and S120 of the method for producing an amorphous tungstic acid fusion material according to an embodiment of the present invention in more detail in terms of a time flow.

[0056] As shown in FIG. 2, in one embodiment of the present application, step (S110) may include a step (S112) of mixing a tungsten raw material with a carbonate and melting the mixture at a high temperature, and a step (S114) of cooling the molten mixture and then dissolving the tungstate aqueous solution in water.

[0057] In an embodiment of the present application, the tungsten raw material is a raw material containing tungsten, and may include ore, sludge, scrap, etc. The tungsten raw material may be crushed and oxidized as a pretreatment step for more efficiently performing step (S112) before being mixed with carbonate. Specifically, the ore of the tungsten raw material is crushed and screened repeatedly, and the sludge is dried and crushed to remove oil present in the sludge and to produce oxide particles of a suitable size. The scrap is subjected to a repeated process of oxidation and crushing to produce oxide particles of a suitable size. In this case, the oxidation temperature may be 800 to 1000°C.

[0058] The tungsten raw material prepared as above is mixed with carbonate and melted at high temperature (S112). At high temperature, the carbonate and tungsten combine to form a tungsten compound, which becomes water-soluble. In one embodiment of the present application, the carbonate may be sodium carbonate (Na2CO3). That is, in step (S112), the tungsten raw material and sodium carbonate are mixed in an appropriate ratio and melted at high temperature to produce water-soluble sodium tungstate (Na2WO4).

[0059] In one embodiment of the present application, the tungsten raw material and sodium carbonate may be mixed in a ratio of 1:0.4-1. If the ratio of sodium carbonate to the tungsten raw material is less than 0.4, the amount of sodium carbonate is relatively too low compared to the amount of tungsten. Therefore, it is disadvantageous that the equivalent amount at which sodium and tungsten can be combined cannot be reached, and there may be residual tungsten that cannot be combined with sodium tungstate (Na2WO4). If the ratio exceeds 1, there is a disadvantage that the amount of impurity removal due to over-feeding in the subsequent process increases, since sodium is also an impurity that must be removed after all. Therefore, the ratio is preferably 0.4-1.

[0060] In one embodiment of the present application, the melting temperature in step (S112) may be 800 to 1000° C. At this time, if the melting temperature is less than 800° C., the amount of tungsten that is not combined and melted increases because the melting temperature cannot be reached, resulting in a decrease in recovery rate, and if the melting temperature exceeds 1000° C., a large amount of energy is unnecessarily consumed, increasing production costs, so that the melting temperature is preferably selected from 800 to 1000° C.

[0061] Next, in one embodiment of the present application, the mixture melted in step (S112) is cooled and then poured into water to dissolve the tungstate aqueous solution (S114). The tungsten compound melted in step (S112) is water-soluble, and other components of the tungsten raw material (e.g., cobalt, copper, nickel, alumina, etc.) that have relatively weak binding strength with carbonate do not dissolve in water in the dissolution step and remain as they are, so it is possible to selectively extract the tungstate aqueous solution in step (S114). If the amount of dissolution is less than twice the weight of the tungsten raw material, there is a high possibility that tungsten will remain together with the water-insoluble residue that is not completely dissolved in water. If it exceeds 15 times, the amount of acid solution used to reach a certain pH in the subsequent replacement process may increase, causing a problem of producing fine powder and reducing production efficiency. Therefore, it is appropriate to set the amount of dissolution to 2 to 15 times the weight of the tungsten raw material.

[0062] In addition, in one embodiment of the present application, the specific gravity of the tungstate aqueous solution may be more than 1.01 and less than 1.50, preferably 1.05 to 1.40. It can be characterized that the higher the specific gravity of the tungstate aqueous solution, the more likely the shape of the primary particles of the tungstic acid becomes spherical. Therefore, by adjusting the specific gravity of the tungstate aqueous solution, it is possible to adjust the shape of the primary particles of tungstic acid and further adjust the crystallinity of the amorphous tungstic acid fusion.

[0063] The tungstate aqueous solution provided through steps S112 to S114 is precipitated into tungstic acid through steps S122 to S128, which will be described in more detail below with reference to FIG.

[0064] In one embodiment of the present application, step (S120) may include a step (S122) of adding an ammonium compound to the tungstate aqueous solution, a step (S124) of introducing an acidic solution into the tungstate aqueous solution, a step (S126) of adding hydrogen peroxide to the tungstate aqueous solution, and a step (S128) of heating and stirring the tungstate aqueous solution.

[0065] Meanwhile, in one embodiment of the present invention, the ammonium compound and hydrogen peroxide may be added after the acid solution is added, but adding the ammonium compound before the acid solution is advantageous in terms of forming particles with a more uniform distribution, and adding the hydrogen peroxide after the acid solution is advantageous in that tungstic acid can be precipitated under the same pH condition, so that powder with a more regular shape can be produced, so we will focus on an embodiment in which the ammonium compound is added before the acid solution is added and the hydrogen peroxide is added after the acid solution is added. Also, according to one embodiment of the present invention, hydrofluoric acid (HF) may be added instead of hydrogen peroxide, and we will focus on an embodiment in which hydrogen peroxide is used, because the effect of recrystallization and coagulation is superior when hydrogen peroxide is used rather than hydrofluoric acid.

[0066] First, in one embodiment of the present application, an ammonium compound may be added and dissolved as an additive in the tungstate aqueous solution provided in step (S110) (S122). In order to distinguish the additive added in step (S122) from the additive added in the following step (S126), the ammonium compound in step (S122) is referred to as a first additive, and hydrogen peroxide in step (S126) is referred to as a second additive.

[0067] In one embodiment of the present application, the tungstate aqueous solution may be a sodium tungstate aqueous solution (Na2WO4(aq)). In the following, the embodiment in which the tungstate aqueous solution is a sodium tungstate aqueous solution will be mainly discussed.

[0068] According to one embodiment of the present invention, the ammonium compound is an ammonium ion (NH + ), and may include at least one of ammonium chloride (NH4Cl), ammonium nitrate (NH4NO3), ammonium carbonate ((NH4)2CO3), ammonium bicarbonate (NH4HCO3), ammonium sulfate ((NH4)2SO4), ammonium fluoride (NH4F), ammonium oxalate ((NH4)2C2O4), ammonium acetate (NH4CH3CO2), monoammonium phosphate (NH4H2PO4), and diammonium phosphate ((NH4)2HPO4). The first additive containing ammonium ions can act as a dispersant for tungstic acid precipitated from the sodium tungstate aqueous solution, as described below. The ammonium ions (NH4 + ) is the tungstate ion (WO4 - ) to sodium ion (Na + ) in the sodium tungstate aqueous solution, the binding strength is weaker than that of tungstate ions (WO4 - ) and does not form a new compound, and as described below, can stably play the role of a dispersant in the sodium tungstate aqueous solution. In one embodiment of the present application, the ammonium compound may be added in an amount of 1 to 10 g per 100 ml of the sodium tungstate aqueous solution. If less than 1 g of the ammonium compound is added per 100 ml of the sodium tungstate aqueous solution, the effect as a dispersant is poor and particle clumping phenomenon may occur. If more than 10 g is added, the ammonium ions become too many, so that the ammonium ions, tungsten ions, and sodium ions can be bonded together, making it difficult to remove sodium in the subsequent process. In addition, unnecessary excessive addition causes an increase in production costs. Therefore, it is preferable that the ammonium compound is added in an amount of 1 to 10 g per 100 ml of the sodium tungstate aqueous solution.

[0069] Next, in one embodiment of the present application, an acidic solution may be added to the tungstic acid aqueous solution having the ammonium compound dissolved therein (S124). The acidic solution may include at least one of hydrochloric acid (HCl), nitric acid (HNO3), and sulfuric acid (H2SO4). The acidic solution lowers the pH of the sodium tungstate aqueous solution, creating an environment in which tungstic acid can be precipitated from the sodium tungstate aqueous solution when the aqueous solution reaches a certain pH value. The certain pH value may be 1 to 2 or less. The acidic solution is added to the sodium tungstate aqueous solution to precipitate sodium ions (Na + ) to hydrogen ions (H + ) as a substitution agent. That is, when the pH of the sodium tungstate aqueous solution reaches a certain value (for example, 1 or less) after the acid solution is added, the sodium ions of the sodium tungstate are replaced by hydrogen ions in the aqueous solution, and water-insoluble tungstic acid is formed and begins to precipitate in the aqueous solution. The acid solution may be added in an amount of 20 to 80 ml per 100 ml of the sodium tungstate aqueous solution. If less than 20 ml of the acid solution is added per 100 ml of the sodium tungstate aqueous solution, it may not be possible to reach a certain pH value (for example, 1 to 2) at which tungstic acid precipitates, and the equivalent amount at which sodium ions (Na+) and hydrogen ions (H+) can be replaced may not be met, resulting in poor recovery rate. If more than 80 ml is added, irregular particles may be generated due to the influence of the excessively added acid solution, and the amount of solution that must be handled in the subsequent process increases, resulting in poor productivity. Therefore, it is preferable that the acidic solution is added in an amount of 20 to 80 ml per 100 ml of the aqueous sodium tungstate solution.

[0070] In an embodiment of the present disclosure, immediately after the acid solution is added, stirring may be performed to thoroughly mix the acid solution in the sodium tungstate aqueous solution.

[0071] Next, in one embodiment of the present application, hydrogen peroxide (H2O2) is added as a second additive to the tungstic acid aqueous solution to which the acidic solution has been added (S126). Hydrogen peroxide can act as a dissolving agent for tungstic acid precipitated in the aqueous solution. As previously described, when the pH of the aqueous solution is lowered below a certain value by adding the acidic solution, water-insoluble tungstic acid begins to precipitate. At this time, hydrogen peroxide dissolves the precipitated tungstic acid, so that tungstic acid particles can be formed in a desired shape, as described below. Meanwhile, since hydrofluoric acid can also dissolve tungstic acid precipitated in the sodium tungstate aqueous solution, hydrofluoric acid can be added as the second additive according to another embodiment of the present invention. The second additive can be added in an amount of 1 to 20 ml per 100 ml of the sodium tungstate aqueous solution. If less than 1 ml of the second additive is added per 100 ml of the sodium tungstate aqueous solution, undissolved tungstic acid may exist, which may cause irregular particle formation. If the amount of the second additive is more than 20 ml, it takes a long time for tungstic acid to be produced after dissolution, and the addition of a large amount of hydrogen peroxide solution can raise the pH, which may lead to a situation where an acidic solution must be added to lower the pH. This is inefficient. Therefore, the second additive is preferably added in the range of 1 to 20 ml per 100 ml of the sodium tungstate aqueous solution. In one embodiment of the present application, if the second additive is added in an amount of more than 12 ml per 100 ml of the tungstate salt aqueous solution (e.g., sodium tungstate aqueous solution), the proportion of the precipitated primary particles of tungstic acid having an acicular shape may increase. That is, the relatively higher the content of the second additive, the more the shape of the primary particles of tungstic acid may be acicular or a combination of acicular and spherical shapes. Therefore, by adjusting the degree to which the second additive is added in a predetermined amount or more, it is possible to adjust the shape of the primary particles of tungstic acid and further adjust the crystallinity of the amorphous tungstic acid fusion.

[0072] In one embodiment of the present application, the sodium tungstate aqueous solution to which the first additive, the displacing agent and the second additive are respectively added is heated and stirred (S128). At this time, the heating and stirring may be performed at a temperature range of 30 to 75°C and a speed of 60 to 400 rpm for 1 to 6 hours. If the heating temperature is less than 30°C, the precipitation time is long and it is difficult to expect uniform particle formation, and if the heating temperature is more than 75°C, fine powder is formed, making the post-process difficult. If the heating and stirring is performed for less than 1 hour, crystals may not be formed because the reaction time for precipitation is not reached, and if it is performed for more than 6 hours, all reactions have already been completed, so there is no point in having a reaction time of more than 6 hours. And if the stirring speed is less than 60 rpm, it is difficult to apply the production process because particle clumping occurs and it is difficult to adjust uniform pH conditions, and if it is more than 400 rpm, it affects the formation of fine powder and makes it difficult to ensure the uniformity of particles. Therefore, the heating and stirring is preferably performed at a temperature range of 30 to 75°C for 1 to 6 hours at a speed of 60 to 400 rpm. By performing step (S128), tungstic acid fusion particles are produced in which primary particles exist independently and are formed in a cluster-like structure. The tungstic acid particles thus produced are different from particles produced by applying the existing general wet process, in that the particles formed above a certain size have a fixed shape, and thus the breakage phenomenon is improved, and the processing is easy in the subsequent filtration and water washing steps, making it possible to produce a tungstic acid fusion without the existing APT production process.

[0073] In order to control the size and shape of the precipitated tungstic acid particles, the role of additives added to the sodium tungstate aqueous solution will be considered in more detail. As follows, hydrogen peroxide plays a dissolving and coagulating role in the aqueous solution, and ammonium compound plays a dispersing role. When the pH of the sodium tungstate aqueous solution reaches a certain value by the acidic solution, water-insoluble tungstic acid begins to precipitate in the aqueous solution. At this time, hydrogen peroxide is added to dissolve the water-insoluble tungstic acid. As mentioned above, hydrofluoric acid may be used instead of hydrogen peroxide.

[0074] Then, the aqueous solution is heated and stirred under certain conditions, and as time passes, tungstic acid begins to precipitate further, which is a reprecipitation step in which the tungstic acid irregularly generated in the sodium tungstate solution having a high pH value (e.g., pH 14) is dissolved under various identical conditions including the same pH range until the pH value becomes low (e.g., pH 1) at which tungstic acid precipitates, and this can be considered as a recrystallization process for forming regular and shaped particles. Meanwhile, when tungstic acid precipitates, the ammonium compound dissolved in the aqueous solution acts as a dispersant, so that the tungstic acid powder precipitates in a dispersed state without excessive aggregation.

[0075] That is, the tungstic acid powder is dissolved by hydrogen peroxide, and as it undergoes a recrystallization process, the tungstic acid powder aggregates with each other to form fused particles of a certain size or more (dissolving and agglomerating role of hydrogen peroxide), and at the same time, the tungstic acid fused particles formed to a certain size or more are dispersed so as not to aggregate with each other due to the surfactant effect of the ammonium compound (dispersing role of the ammonium compound), so that the particles do not further aggregate and can maintain their shape. If the ammonium compound is not added, the tungstic acid particles formed to a certain size by hydrogen peroxide cannot further maintain their shape, but continue to aggregate with each other in parts, and should be transformed into new amorphous particles that are irregularly elongated horizontally and vertically. Such amorphous particles are vulnerable to external impacts during the subsequent step of repeated water washing. On the other hand, if hydrogen peroxide is not added, the tungstic acid powder precipitated from the sodium tungstate aqueous solution will not dissolve, and will aggregate to form one large lump. In other words, the dissolving and coagulating role of hydrogen peroxide and the dispersing role of ammonium compound in the sodium tungstate aqueous solution complement each other, so that the precipitated tungstic acid powder can form tungstic acid fused particles having a definite shape of a cluster structure in which primary particles exist independently of each other.

[0076] When an acidic solution serving as a displacement agent is added to a sodium tungstate aqueous solution, the pH of the aqueous solution reaches a certain value (for example, pH 1 or less), and tungstic acid begins to precipitate from the sodium tungstate aqueous solution. The precipitated tungstic acid powder has a tendency to aggregate with each other in an amorphous manner (see the left side of FIG. 3).

[0077] Referring to the left side of Fig. 3, tungstic acid particles produced by a conventional wet process without ammonium compounds and hydrogen peroxide are shown. As shown in the left side of Fig. 3, the size of the particles formed by the aggregation of tungstic acid powder is amorphous and irregular, with some being horizontally elongated and others being vertically elongated. This makes it difficult to perform subsequent processing by easily breaking into small pieces during the subsequent repeated filtration and water washing steps.

[0078] However, when an ammonium compound and hydrogen peroxide are added to the sodium tungstate aqueous solution according to an embodiment of the present invention, the tungstic acid powder precipitated from the sodium tungstate aqueous solution is dissolved and coagulated by hydrogen peroxide, and dispersed by the ammonium compound, so that the precipitated tungstic acid powder is generally uniformly aggregated and dispersed to form particles with a fixed shape (see the right side of FIG. 3). As shown in the right side of FIG. 3, the mutual complementation between hydrogen peroxide and the ammonium compound in the tungstate aqueous solution results in the formation of tungstic acid particles with a fixed shape like bunches of grapes that are separated one by one. The tungstic acid fusion particles of this shape are improved in the subsequent step in the breakage phenomenon caused by repeated washing with water, and can be easily filtered and washed with water, so that tungsten oxide, tungsten powder, or tungsten carbide can be produced immediately in a subsequent process without the APT manufacturing process.

[0079] Next, the steps of producing tungsten oxide using the tungstic acid obtained through the above steps (S122 to S128) will be considered.

[0080] As shown in FIG. 2, a method for preparing a tungstic acid fusion according to an embodiment of the present disclosure may include a step of filtering and washing the heated and stirred aqueous solution to obtain crystalline tungstic acid particles containing moisture (S132), and a step of drying the tungstic acid particles to remove moisture (S134).

[0081] First, in one embodiment of the present application, in step (S132), the solution obtained in step (S128) is filtered in a filtration device, and acid washing and distilled water washing are repeated. Through step (S132), tungstic acid particles in a crystalline form containing moisture can be obtained. The tungstic acid fusion particles according to one embodiment of the present application can be smoothly washed repeatedly because the powder breakage phenomenon caused by repeated washing is improved. Filter paper can be used for filtering, and the hole size of the filter paper can be determined in consideration of the effective size of tungstic acid particles. Preferably, the size of the tungstic acid particles obtained according to one embodiment of the present application may be approximately 3 μm or more, so that filter paper having a hole size of 3 μm or less can be selectively used.

[0082] In one embodiment of the present application, the acid solution used in the acid washing may be the same as the displacing agent solution used in step (S124). This is advantageous in terms of process efficiency. For example, at least one of hydrochloric acid (HCl), nitric acid (HNO3), and sulfuric acid (H2SO4) may be used. The concentration of the acid solution used in the acid washing may be 1 to 10%. If the concentration of the acid solution is less than 1%, the impurity removal effect is poor, and if it exceeds 10%, it causes an increase in washing water during the distilled water washing process, so it is preferable to select the concentration of the acid solution within the range of 1 to 10%. The acid washing and distilled water washing may be repeated two or more times. If the number of times of the acid washing and distilled water washing exceeds five times, the amount of distilled water used increases, which increases the production cost and increases the possibility of powder breakage, so it is preferable not to exceed five times.

[0083] In one embodiment of the present application, the water-washed tungstic acid powder can be dried in a dryer to remove moisture (S134). Through step (S134), moisture contained in the tungstic acid fusion particles is removed. At this time, the drying temperature is preferably 60 to 100°C. If the drying temperature is less than 60°C, the drying time is long and the drying efficiency is poor, and if it exceeds 100°C, it is disadvantageous because agglomeration may occur between the powder, so the drying temperature is preferably selected in the range of 60 to 100°C.

[0084] A third aspect of the present application provides a tungsten oxide prepared by calcining the powder of the amorphous tungstic acid fusion.

[0085] Detailed descriptions of parts that overlap with the first and second aspects of the present application have been omitted, but the contents described for the first and second aspects of the present application may be equally applied even if the description is omitted in the third aspect.

[0086] The tungsten oxide according to the third aspect of the present application will be described in detail below.

[0087] In one embodiment of the present application, a calciner may be used in air or vacuum for the calcination treatment, and the calcination temperature is preferably 500 to 1000° C. and the calcination time is preferably 1 to 6 hours. If the calcination temperature is less than 500°C or the calcination time is less than 1 hour, the crystal structure does not change well from tungstic acid to tungsten oxide. If the calcination temperature is more than 1000°C or the calcination time is more than 6 hours, the powder hardens and causes problems in subsequent processes. Therefore, it is preferable to select the calcination temperature in the range of 500 to 1000°C and the calcination time in the range of 1 to 6 hours.

[0088] A fourth aspect of the present application provides a tungsten powder produced by reducing the powder of the amorphous tungstic acid fusion.

[0089] Detailed descriptions of parts that overlap with the first to third aspects of the present application have been omitted, but the contents described for the first to third aspects of the present application may be equally applied even if the description is omitted in the fourth aspect.

[0090] In one embodiment of the present application, the tungsten powder may be prepared by hydrogen reduction of the amorphous tungstic acid fusion powder. The temperature for the reduction treatment may be 900 to 1200°C. If the temperature is less than 900°C, the conversion from tungstic acid to tungsten is not performed well, and if the reduction treatment temperature exceeds 1200°C, agglomeration occurs between the particles of the powder, causing hard solidification and problems in the subsequent process. Therefore, it is preferable to select the reduction treatment temperature in the range of 900 to 1200°C.

[0091] In a fifth aspect of the present application, there is provided a tungsten carbide powder, which is manufactured by mixing the amorphous tungsten acid fusion powder with carbon powder and carburizing the mixture.

[0092] Detailed descriptions of parts that overlap with the first to fourth aspects of the present application will be omitted, and the contents described in the first to fourth aspects of the present application may be equally applied even if the description is omitted in the fifth aspect.

[0093] In one embodiment of the present application, the carburizing treatment may be performed at a temperature of 900 to 1300° C. If the temperature is less than 900° C., the conversion from tungstic acid to tungsten carbide may not be completed well, and if the reduction treatment temperature exceeds 1300° C., agglomeration may occur between powder particles, resulting in the formation of unnecessarily large powder, which may harden and cause problems in subsequent processes. Therefore, it is preferable to select the carburizing treatment temperature in the range of 900 to 1300° C.

[0094] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention may be embodied in various different forms and should not be construed as being limited to the embodiments set forth herein.

[0095] Example 1. Preparation of tungstic acid fusions

[0096] The tungsten raw powder was mixed with sodium carbonate in a weight ratio of 1:0.6 and placed in a container, then placed in a box-type electric furnace and melted at high temperature for 6 hours at 800℃ in an air atmosphere. The melt was then cooled to room temperature and poured into water to dissolve only the tungsten, which was then filtered to produce a sodium tungstate (Na2WO4) aqueous solution.

[0097] The ammonium compound was added to 300 ml of the prepared sodium tungstate aqueous solution and dissolved by stirring, and then 100 ml of acid solution and hydrogen peroxide solution (H2O2, 35%) were added according to Table 1 below, and the temperature was kept at 45-50°C and the stirring speed was kept at about 100 rpm, and the reaction was carried out for about 6 hours to precipitate tungstic acid (H2WO4).

[0098] Then, in order to separate the tungstic acid from the solution, the filter paper was placed in a filter device and filtered. An acid washing solution (HCl, 3.5%) was made, and the solution was washed twice with water, then washed three times with distilled water, and then dried in a dryer maintained at 85℃ to form a tungstic acid fusion product.

[0099] [Table 1]

[0100] Example 2. Preparation of tungstic acid fusions

[0101] A tungstic acid fusion compound was prepared in the same manner as in Example 1, except that the conditions were changed as shown in Table 2 below.

[0102] [Table 2]

[0103] Example 3. Preparation of tungstic acid fusions

[0104] A tungstic acid fusion compound was prepared in the same manner as in Example 1, except that the conditions were changed as shown in Table 3 below.

[0105] [Table 3]

[0106] Experimental Example 1. SEM analysis of particle shape of tungstic acid fusion

[0107] 4 to 6 show SEM images of the tungstic acid fusions of Examples 1 to 3 prepared as above.

[0108] Referring to FIG. 4, it can be seen that the primary particles of the tungstic acid fusion prepared in Example 1 are spherical and have a clustered shape like grapes, each of which is separated from the others.

[0109] Referring to FIG. 5, it can be seen that the tungstic acid fusion product prepared in Example 2 has a needle-like shape, a relatively crystalline structure, and a particle shape in which the needle-like primary particles are clustered and spread out.

[0110] Referring to FIG. 6, it can be seen that the shape of the primary particles of the tungstic acid fusion prepared in Example 2 includes both spherical and acicular shapes, and that the crystallinity is mixed with that of high and low. The aggregated shape is a particle shape with a bunch-like structure resembling a bunch of grapes.

[0111] Experimental Example 2. Tungsten acid fusion XRD peak analysis

[0112] The tungsten fusion powder prepared and dried in the above example was placed in a sample holder and compressed to flatten the surface to prepare a sample for XRD analysis. The sample was then attached to a high-resolution X-ray diffraction analyzer (Bruker, D8 ADVANCE). The analysis conditions were set to a diffraction angle of 10° to 80°, a diffraction speed of 0.2 seconds, and a diffraction interval of 0.02 step to perform the XRD analysis of the tungsten fusion.

[0113] 7 to 9 show the XRD peak results of the tungstic acid fusions of Examples 1 to 3. To interpret the peak results, the XRD-JCPDS CARD of WO3·H2O Tungstite was referred to, which showed that the pattern calculated by X-ray diffraction showed major peaks at 2θ of about 16.5390° (hereinafter referred to as the first peak), 25.6377° (hereinafter referred to as the second peak), and 35.0352° (hereinafter referred to as the third peak), and the intensities were about 565.999 and 160, respectively.

[0114] 7, in the range of 16.5390±0.1° of 2θ, the peak corresponding to the first peak of WO3·H2O tungstite is hardly observed, and therefore, the ratio of the corresponding peak intensity to the X-ray diffraction peak intensity of WO3·H2O may be formed to be about 0.001 to 0.03. In addition, in the range of 25.6377±0.1°, the peak corresponding to the second peak of WO3·H2O tungstite is weakly observed, but a shift occurs or the peak is broadened, and therefore, the ratio of the corresponding peak intensity to the X-ray diffraction peak intensity of WO3·H2O may be formed to be about 0.001 to 0.1. In addition, in the range of 35.0352±0.1°, the peak corresponding to the third peak of WO3·H2O Tungstite is weakly shown, but it is shifted or the peak is broadly formed, and therefore the ratio of the peak intensity to the X-ray diffraction peak intensity of WO3·H2O can be formed to about 0.001 to 0.1. Therefore, in summary, the main peak intensity is not characteristically strong, but is widely distributed, which can be seen as meaning that the crystallinity is relatively low and the crystal size is uniform. In other words, when the shape of the primary particles of tungstic acid is spherical, the crystallinity is low and the crystal size can be uniform.

[0115] Referring to FIG. 8, a peak corresponding to the first peak of WO3·H2O tungstite is strongly indicated in the range of 16.5390±0.1° of 2θ (intensity of 750 to 1100), and the ratio of the corresponding peak intensity to the X-ray diffraction peak intensity of WO3·H2O can be formed to be about 0.5 to 2.3. It was also observed that the FWHM (full width at half maximum) of the corresponding peak is 0.30° to 1.0°. In addition, a peak corresponding to the second peak of WO3·H2O tungstite is strongly indicated in the range of 25.6377±0.1° (intensity of 1350 to 1900), and therefore, the ratio of the corresponding peak intensity to the X-ray diffraction peak intensity of WO3·H2O can be formed to be about 0.5 to 2.3. It was also found that the FWHM (full width at half maximum) of the corresponding peak was 0.20° to 0.90°. In addition, a peak corresponding to the third peak of WO3·H2O tungstite was observed in the range of 35.0352±0.1° (intensity of 300 to 450), which indicates that the ratio of the corresponding peak intensity to the X-ray diffraction peak intensity of WO3·H2O can be formed at about 0.5 to 1.3. It was also found that the FWHM (full width at half maximum) of the corresponding peak was 0.30° to 1.10°. In summary, it was confirmed that the intensity of the main peak was characteristically stronger than that of WO3·H2O tungstite, which indicates that when the shape of the primary tungstic acid particles is only needle-shaped, a tungstic acid fusion with a relatively high degree of crystallinity is formed.

[0116] In the case of FIG. 9, in the range of 16.5390±0.1° of 2θ, the peak corresponding to the first peak of WO3·H2O Tungstite is shown to be relatively strong (intensity of 330 to 480), and the ratio of the peak intensity to the X-ray diffraction peak intensity of WO3·H2O can be formed to be about 0.5 to 1.2. It was also observed that the FWHM (full width at half maximum) of the peak is 0.30° to 1.0°. In the range of 25.6377±0.1°, the peak corresponding to the second peak of WO3·H2O Tungstite is also shown to be relatively strong (intensity of 450 to 820), and therefore, the ratio of the peak intensity to the X-ray diffraction peak intensity of WO3·H2O can be formed to be about 0.5 to 1.2. It was also found that the FWHM (full width at half maximum) of the corresponding peak was 0.20° to 0.90°. In addition, a peak corresponding to the third peak of WO3·H2O tungstite was observed in the range of 35.0352±0.1° (intensity of 200 to 290), which indicates that the ratio of the corresponding peak intensity to the X-ray diffraction peak intensity of WO3·H2O can be formed to about 0.5 to 1.3. It was also found that the FWHM (full width at half maximum) of the corresponding peak was 0.30° to 1.10°. In summary, the intensity of the main peak was stronger to a certain level compared to WO3·H2O tungstite, but the intensity was weaker compared to Example 2, while the peak distribution was relatively broad. This means that the shape of the primary particles of tungstic acid is a combination of needle-like and spherical shapes, and there is a mixture of parts with relatively good crystallinity and parts with poor crystallinity.

[0117] Experimental Example 3. Particle size distribution analysis of tungstic acid fusion

[0118] 10 to 12 show the particle size distribution analysis results of the tungstic acid fusions of Examples 1 to 3 prepared as above.

[0119] Referring to FIG. 10, the D 50 The standard deviation of the diameter of the amorphous tungstic acid fusion is about 3.10 μm, and it can be seen that when the primary particles of tungstic acid are spherical, the particle size of the tungstic acid fusion is relatively uniform and the size can be well controlled to 30 μm or less.

[0120] Referring to FIG. 11, the D 50 The standard deviation of the diameter of the amorphous tungstic acid fusion is about 6.47 μm. In this case, the shape of the primary particles of tungstic acid is needle-like. 50 Although the standard deviation of the diameter was relatively large, it can be confirmed that the particle size of the tungstic acid fusion is relatively uniform, and the size can be well controlled to 35 μm or less with a particle distribution of about 99%.

[0121] Referring to FIG. 12, the D 50 The standard deviation of the diameter of the amorphous tungstic acid fusion was about 7.27 μm, and the standard deviation of the diameter of the amorphous tungstic acid fusion was about 2.92 μm. From this, it was confirmed that when the shape of the primary particles of tungstic acid is a combination of needle-like and spherical, the particle size of the tungstic acid fusion is relatively uniform, similar to Example 1, and the size can be well controlled to 30 μm or less. [Industrial Applicability]

[0122] According to one embodiment of the present invention, it is possible to provide an environmentally friendly, low-cost process technology that reduces process costs by not performing the APT process and significantly reduces air and water pollutant emissions.

[0123] In addition, according to an embodiment of the present invention, since it does not require the development of special equipment and devices, it is possible to provide a manufacturing process for tungsten material that is easily commercialized.

Claims

1. An amorphous tungstic acid fusion product formed by agglomerating primary particles of tungstic acid, The amorphous tungstic acid fusion is characterized in that the tungstic acid primary particles are interconnected to form a cluster-like structure.

2. The amorphous tungstic acid fusion of claim 1, wherein the shape of the tungstic acid primary particles is spherical, acicular, or a combination thereof.

3. The amorphous tungstic acid fusion of claim 1, wherein the tungstic acid primary particles are spherical particles having a diameter of 0.01 to 2.0 μm.

4. The tungstic acid primary particles have a length (L) of 0.01 to 1.8 μm; The amorphous tungstic acid fusion of claim 1, characterized in that the fusion particles are acicular particles having an aspect ratio (L / D) of 12 to 24.

5. The amorphous tungstic acid fusion of claim 1, wherein the diameter of the amorphous tungstic acid fusion is 30 μm or less.

6. D according to the particle size distribution of the amorphous tungstic acid fusion obtained by measuring by a laser diffraction scattering type particle size distribution measurement method ５０ The amorphous tungstic acid fusion of claim 1, wherein the diameter of the amorphous tungstic acid fusion is 5 to 12 μm.

7. 2. The amorphous tungstic acid fusion of claim 1, wherein the standard deviation of the diameter of the amorphous tungstic acid fusion is 1.5 to 7 μm.

8. The amorphous tungstic acid fusion according to claim 1, wherein at least 80% of the primary particles of tungstic acid are fused and bonded to each other by at least five particles.

9. The tungstic acid primary particles consist of acicular particles and spherical particles, The amorphous tungstic acid fusion material according to claim 2, wherein the tungstic acid primary particles have a ratio of (weight of acicular particles):(weight of spherical particles) of 1:0.3 to 3.

10. adding a first additive comprising an ammonium compound to the aqueous tungstate solution; introducing an acidic solution into the tungstate aqueous solution; and adding a second additive, the second additive including at least one of hydrogen peroxide and hydrofluoric acid, to the aqueous solution after the acid solution is added; The specific gravity of the tungstate aqueous solution is greater than 1.01 and less than 1.50; The acid solution is added in an amount of 20 to 80 ml per 100 ml of the tungstate aqueous solution, the first additive is added in an amount of 1 to 10 g per 100 ml of the tungstate aqueous solution, and the second additive is added in an amount of 1 to 20 ml per 100 ml of the tungstate aqueous solution; The amorphous tungstic acid fusion product is a cluster-like structure formed by interconnecting primary particles of tungstic acid, The method for producing an amorphous tungstic acid fused body, wherein the shape of the tungstic acid primary particles is spherical, acicular, or a combination thereof.

11. The method for producing an amorphous tungstic acid fused material according to claim 10, wherein the shape of the primary particles of tungstic acid is acicular or a combination of acicular and spherical shapes.

12. A tungsten oxide produced by calcining the powder of the amorphous tungstic acid fusion of claim 1.

13. A tungsten powder produced by reducing the amorphous tungstic acid fused powder of claim 1.

14. A tungsten carbide powder produced by carburizing the amorphous tungsten acid fused powder of claim 1.

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