KR101800811B1 - Method for manufacturing tungsten oxide and tungsten oxide manufactured by the same - Google Patents

Abstract

The present invention relates to a method for producing tungsten oxide via a wet-type process, and tungsten oxide produced thereby. The method for producing tungsten oxide comprises the following steps: eluting tungstic acid by inserting an acidic solution into a tungstate aqueous solution; and acquiring tungsten oxide from the tungstic acid. The elution step involves the use of a first additive containing ammonium compound, and a second additive containing at least one of hydrogen peroxide and hydrofluoric acid. According to the present invention, it is possible to reduce production costs for tungsten oxide.

Description

METHOD FOR MANUFACTURING TUNGSTEN OXIDE AND TUNGSTEN OXIDE MANUFACTURED BY THE SAME,

The present invention relates to a tungsten oxide production process and tungsten oxide produced thereby, and more particularly to a tungsten oxide production process using a wet process and tungsten oxide produced thereby.

Tungsten oxide is used in various fields such as photocatalyst, electrochromic, electronic device and sensor.

The tungsten oxide may be prepared by a variety of methods including dry leaching or wet leaching. Typically, the wet process involves the production of ammonium para tungstate (APT: (NH ₄ ) ₁₀ W ₁₂ O ₄₁ .5H ₂ O).

The APT manufacturing process is a process of forming and crystallizing tungsten compounds using ammonia. In order to discharge the ammonia gas generated in this process, a treatment facility should be constructed to meet atmospheric environment standards. This greatly increases the cost of manufacturing tungsten oxide.

Embodiments of the present invention provide a cost saving tungsten oxide manufacturing method and tungsten oxide produced thereby.

According to an embodiment of the present invention, there is provided a method for producing tungsten oxide, comprising: depositing tungstic acid by introducing an acidic solution into a tungstate aqueous solution; And obtaining tungsten oxide from the tungstic acid, wherein the step of precipitating may include using a first additive including an ammonium compound and a second additive including at least one of hydrogen peroxide and hydrofluoric acid.

The first additive is ammonium chloride (NH ₄ Cl), ammonium nitrate (NH ₄ NO _3), ammonium carbonate ((NH _{4) 2} CO _3), ammonium bicarbonate (NH ₄ HCO _3), ammonium sulfate ((NH _{4) 2} SO _4), ammonium fluoride (NH ₄ F), ammonium oxalate _{((NH 4) 2 C 2} O 4), ammonium acetate _{(NH 4 CH 3 CO 2)} , phosphate, ammonium (NH ₄ H ₂ PO _4), and the phosphate may include at least one of ammonium _{((NH 4) 2 HPO 4} ).

The second additive may serve as a dissolving agent for dissolving the tungstic acid powder so that the particles formed by the precipitated tungstic acid powder do not exceed a predetermined size.

The first additive may serve as a dispersing agent for dispersing the particles so that the particles formed by the precipitated tungstic acid powder have a definite shape.

The acidic solution may include at least one of hydrochloric acid (HCl), nitric acid (HNO ₃ ), and sulfuric acid (H ₂ SO ₄ ).

The tungstate may include sodium tungstate (Na ₂ WO ₄ ).

The particles of the precipitated tungstic acid powder may each have a diameter of 10 to 30 탆.

This technology can reduce the manufacturing cost of tungsten oxide.

FIG. 1 is a flowchart showing a method of manufacturing tungsten oxide according to an embodiment of the present invention over time.
FIG. 2 is a flowchart showing the step of providing a tungstate aqueous solution according to an embodiment of the present invention in more detail according to time.
FIG. 3 is a flowchart showing the step of depositing tungstic acid according to an embodiment of the present invention in more detail over time.
Figure 4 is an enlarged view of the tungstic acid particles produced according to a conventional wet process, with no additives according to an embodiment of the present invention.
5 is an enlarged view of the tungstic acid particles produced according to an embodiment of the present invention.
6 is a flowchart showing the step of acquiring tungsten oxide according to an embodiment of the present invention in more detail over time.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a flowchart showing a method of manufacturing tungsten oxide according to an embodiment of the present invention over time.

As shown in FIG. 1, the method for producing tungsten oxide includes the steps of providing a tungstate aqueous solution (S110), depositing tungstic acid from a tungstate aqueous solution (S120), and obtaining tungsten oxide from tungstic acid S130).

The method for producing tungsten oxide according to an embodiment of the present invention may correspond to a wet process since tungstic acid (H ₂ WO ₄ ) is precipitated from an aqueous solution of tungstate.

When a tungsten oxide is produced by a wet process, ammonium paratungstate (APT) production process is usually included, but according to the embodiment of the present invention, the APT production process can be omitted.

When accompanied by the APT manufacturing process, it involves various drawbacks due to the nature of the manufacturing process. In particular, the APT process uses ammonia to form and crystallize tungsten compounds, so the evaporation / concentration process in the crystallization step requires a lot of energy and generates a large amount of ammonia gas. Ammonia gas is expensive to process and makes domestic tungsten production more difficult.

Despite the high cost, the APT manufacturing process is necessary because the tungstate powder forms fine and incomplete particles during the process of replacing tungstate with tungstate. The tungstic acid particles formed in the substitution process are further broken down through the repeated water washing process. As the size of the tungstic acid particles is minute and irregular, the subsequent filtration and washing process becomes more difficult. Here, the APT manufacturing process can increase the size of the tungstic acid particles and make the shape uniform, so that the tungstic acid particles can be smoothly handled in the subsequent treatment including the filtration and the washing process.

In view of these points, the method for producing tungsten oxide according to an embodiment of the present invention proposes a method for obtaining tungstic acid particles corresponding to the particle size of tungstic acid produced by a conventional wet process without APT production process.

The method for preparing tungsten oxide according to an embodiment of the present invention controls the particle size and shape formed by using an additive in the process of substituting tungstate for tungstate. The particle size can be as large as that of the tungstic acid particles produced by the APT manufacturing process, and the shape of the grains has a shape of grapevine clusters that are not easily broken even in the repetitive washing process.

An additive according to an embodiment of the present invention is a first additive of an ammonium compound and a second additive comprising at least one of hydrogen peroxide and hydrofluoric acid. By using the above additives in the substitution process, the tungstic acid powder to be precipitated dissolves, coagulates and disperses in the powder, so that particles having a uniform shape of a predetermined size or more can be produced, thereby improving the process efficiency in the subsequent filtration and washing steps.

Hereinafter, the present invention will be described in more detail with reference to FIGS. 2 to 6. FIG.

FIG. 2 is a flowchart showing a step (S110) of providing a tungstate aqueous solution according to an embodiment of the present invention in more detail in accordance with the passage of time.

As shown in FIG. 2, step S110 is a step (S112) of mixing a tungsten raw material and a carbonate and melting the mixture at a high temperature (S112), cooling the molten mixture and then introducing water into the water to elute the tungstate aqueous solution (S114) . ≪ / RTI >

The tungsten raw material is a raw material containing tungsten, and may include ores, sludge, scrap, and the like.

The tungsten raw material can be pulverized and oxidized as a pretreatment step to perform Step S112 more efficiently before mixing with the carbonate. Specifically, the ore in the tungsten raw material is subjected to repetitive pulverization and sorting, and the sludge is dried and pulverized to remove the oil present in the sludge and make it into granules of an appropriate size. The scrap is repeatedly oxidized and pulverized to make granules of appropriate size. The oxidation temperature may be 800-1000 < 0 > C.

The carbonate is mixed with the prepared tungsten raw material and melted at a high temperature (S112).

At high temperatures, the carbonate and tungsten combine to form a tungsten compound, where the tungsten compound becomes water soluble.

The carbonate may be sodium carbonate (Na ₂ CO ₃ ). That is, in the step (S112) and melting at high temperature a mixture of the tungsten raw material with sodium carbonate in an appropriate ratio, to produce a water-soluble sodium tungstate (Na ₂ WO _4).

According to an embodiment of the present invention, the tungsten raw material and sodium carbonate may be mixed in a ratio of 1: 0.4 to 1. When the ratio of sodium carbonate to tungsten raw material is less than 0.4, the amount of sodium carbonate is relatively lower than the amount of tungsten. Thus, it is disadvantageous that the equivalent amount of sodium and tungsten can not be reached and there may be residual tungsten which can not bind with sodium tungstate (Na ₂ WO ₄ ). If the ratio is more than 1, sodium is also an impurity which must eventually be eliminated, and therefore, there is a disadvantage that the amount of impurity removal due to over-feeding is increased in the post-process. Therefore, the ratio is preferably 0.4 to 1.

The melting temperature in step S112 may be 800-1000 < 0 > C. If the melting temperature is lower than 800 ° C, the melting temperature is not reached, and the amount of tungsten that is bound or not dissolved increases, which lowers the recovery rate. If the melting temperature exceeds 1000 ° C, It is preferable that the melting temperature is selected from 800 to 1000 占 폚.

Next, in step S112, the molten mixture is cooled and then put into water to elute the tungstate aqueous solution (S114).

The molten tungsten compound in step S112 is water soluble and the other components (e.g., cobalt, copper, nickel, alumina, etc.) of the tungsten raw material having relatively low bonding strength with the carbonate remain untouched in the eluting step , It is possible to selectively extract the tungstate aqueous solution in step S114.

When the amount of eluted water is less than 4 times the weight of the tungsten raw material, there is a high possibility that tungsten may remain in the residue which is insoluble in water and remains insoluble. If it is more than 15 times, the amount of the acidic solution used for reaching a certain pH in the post-process substitution step may be increased, and a problem arises in that fine powder is produced to lower the production efficiency. Therefore, it is appropriate that the amount of eluted water is 4 to 15 times the weight of the tungsten raw material.

The tungstate aqueous solution provided through steps S112 through S114 as described above is precipitated in tungstic acid through the following steps S122 through S128. This will be described in more detail with reference to FIG.

FIG. 3 is a flowchart showing a step (S120) of depositing tungstic acid according to an embodiment of the present invention in more detail over time.

As shown in FIG. 3, step S120 includes adding an ammonium compound to the tungstate aqueous solution (S122), adding an acidic solution to the aqueous tungstate solution (S124), adding hydrogen peroxide to the tungstate aqueous solution (S126), and heating and stirring the aqueous tungstate solution (S128).

Meanwhile, according to another embodiment of the present invention, the ammonium compound and hydrogen peroxide may be added after the acidic solution is added, but the addition of the ammonium compound before the acidic solution is advantageous in terms of particle formation with a more even distribution, The addition of hydrogen peroxide after the addition of the solution is advantageous in that tungstic acid can be precipitated under the same pH conditions and powder production with more regular fixation is possible. Therefore, before the acid solution is added, the ammonium compound is added, Hereinafter, an embodiment in which hydrogen peroxide is added will be mainly described.

In addition, according to another embodiment of the present invention, hydrofluoric acid (HF) may be added instead of hydrogen peroxide, but hydrogen peroxide is more effective than hydrogen fluoride in that the effect of recrystallization and agglomeration is excellent. see.

First, an ammonium compound is added as an additive to the tungstate aqueous solution provided from step S110 and dissolved (S122).

The ammonium compound in step S122 is referred to as a first additive and the hydrogen peroxide in step S126 is referred to as a second additive in order to distinguish the additive to be added in step S122 from the additive to be added in the subsequent step S126 .

The tungstate aqueous solution may be an aqueous sodium tungstate solution (Na ₂ WO ₄ (aq)). Hereinafter, the tungstate aqueous solution is an aqueous solution of sodium tungstate.

Ammonium compound according to an embodiment of the present invention is a compound of the water-soluble comprises an ammonium ion (NH ₄ +), ammonium chloride (NH ₄ Cl), ammonium nitrate (NH ₄ NO _3), ammonium carbonate ((NH _{4) 2} CO ₃ ), ammonium bicarbonate (NH ₄ HCO ₃ ), ammonium sulfate ((NH ₄ ) ₂ SO ₄ ), ammonium fluoride (NH ₄ F), ammonium oxalate ((NH ₄ ) ₂ C ₂ O ₄ ) NH ₄ CH ₃ CO ₂ ), monoammonium phosphate (NH ₄ H ₂ PO ₄ ), ammonium dihydrogen phosphate ((NH ₄ ) ₂ HPO ₄ ).

The first additive comprising ammonium ions can act as a dispersant for tungstic acid precipitated from an aqueous solution of sodium tungstate as described below.

Ammonium ions of the ammonium compounds (NH ₄ +) is a sodium tongue tungstate ion in State solution (WO ₄ -) the binding force than sodium ion (Na +) weak against a, a tongue in the sodium tungstate solution state ions (WO ₄ -) And can act as a dispersant stably in an aqueous sodium tungstate solution as described below without forming a new compound.

The ammonium compound may be added in an amount of 1 to 10 g per 100 ml of the aqueous sodium tungstate solution. If less than 1 g of the ammonium compound is added per 100 ml of the aqueous solution of sodium tungstate, the effect as a dispersant may be deteriorated and the aggregation of the particles may occur. When more than 10 g of ammonium ion is added, ammonium ion, tungsten ion and sodium ion can be bonded together as ammonium ion is increased, making it difficult to remove sodium in a post-process. In addition, unnecessary over-addition causes an increase in production cost. Therefore, it is preferable that the ammonium compound is added in an amount of 1 to 10 g per 100 ml of the aqueous sodium tungstate solution.

Next, the acidic solution is introduced into the aqueous tungstic acid solution in which the ammonium compound is dissolved (S124).

Acidic solution may include at least one of hydrochloric acid (HCl), nitric acid (HNO ₃₎ and sulfuric acid (H ₂ SO _4).

The acidic solution lowers the pH of the aqueous solution of sodium tungstate and creates an environment in which tungstic acid can be precipitated from the aqueous solution of sodium tungstate since the aqueous solution reaches a certain pH value. The constant pH value can be 1 to 2 or less.

The acid solution is added to the sodium tungstate aqueous solution to serve as a substituent to replace the sodium ion (Na +) of the sodium tungstate with the hydrogen ion (H +).

That is, when the pH of the sodium tungstate aqueous solution reaches a certain value (for example, 1 or less) by the introduction of the acidic solution, the sodium ion of the sodium tungstate is replaced by the hydrogen ion in the aqueous solution, Tungstic acid is formed and begins to precipitate in aqueous solution.

The acid solution may be added in an amount of 20 to 80 ml per 100 ml of sodium tungstate aqueous solution. If the acidic solution is added to less than 20 ml per 100 ml of sodium tungstate aqueous solution, it may not reach a constant pH value (for example, 1 to 2) at which tungstic acid precipitates and sodium ion (Na +) and hydrogen ion It is possible to reduce the recovery rate because it is less than the equivalent amount. When the amount exceeds 80 ml, irregular particles may be formed due to the excessively charged acid solution, and the amount of the solution to be handled in the post-process increases, resulting in decreased productivity. Therefore, it is preferable that the acidic solution is added in the range of 20 to 80 ml per 100 ml of the aqueous sodium tungstate solution.

Immediately after the acidic solution is added, the stirring may be performed so that the acidic solution can be mixed well in the sodium tungstate aqueous solution.

Next, hydrogen peroxide (H ₂ O ₂ ) is added as a second additive into the aqueous tungstic acid solution into which the acidic solution has been added (S 126).

Hydrogen peroxide can act as a solubilizer for tungstic acid precipitated in aqueous solution. As described above, when the pH of the aqueous solution becomes lower than a certain value as the acidic solution is introduced, the water-insoluble tungstic acid begins to precipitate. At this time, the hydrogen peroxide dissolves the precipitated tungstic acid, So that tungstic acid particles can be formed. On the other hand, hydrofluoric acid can also dissolve tungstic acid precipitated in an aqueous solution of sodium tungstate, and therefore, according to another embodiment of the present invention, hydrofluoric acid may be added as a second additive.

Hydrogen peroxide may be added in an amount of 1 to 10 ml per 100 ml of aqueous sodium tungstate solution. When hydrogen peroxide is added in an amount of less than 1 ml per 100 ml of the sodium tungstate aqueous solution, undissolved tungstic acid is present, which may cause irregular particle formation. If it is added in an amount exceeding 10 ml, it takes a long time to produce tungstic acid again after dissolution, and a large amount of hydrogen peroxide may increase the pH, which may result in an additional acid solution to lower the pH. This is inefficient. Therefore, hydrogen peroxide is preferably added in the range of 1 to 10 ml per 100 ml of aqueous solution of sodium tungstate.

As described above, the sodium tungstate aqueous solution into which the first additive, the substituent and the second additive are respectively added is heated and stirred (S128).

At this time, heating and stirring may be carried out at a temperature of 30 to 75 ° C at a rate of 60 to 200 rpm for 1 to 6 hours. If the heating temperature is lower than 30 ° C, the time for precipitation becomes long and it is difficult to expect uniform particle formation. When the heating temperature is higher than 75 ° C, fine powder is formed to make post-processing difficult. When the heating and stirring proceed to less than 1 hour, the reaction does not reach the precipitation reaction time and crystals may not be formed. When the reaction proceeds over 6 hours, all the reactions have already been completed. Therefore, There is no meaning. If the agitation speed is less than 60 rpm, the agglomeration of the particles may occur and it is difficult to apply the production process. When the agitation speed is more than 200 rpm, it affects the fine powder formation and it is difficult to ensure the uniformity of the particles. Therefore, it is preferable that heating and stirring are carried out at a temperature of 30 to 75 DEG C for 1 to 6 hours at a rate of 60 to 200 rpm.

 As the step S128 progresses, grape clusters of crystallized tungstic acid particles are generated one by one apart.

The tungstic acid particles thus formed are different from the particles prepared by the conventional wet process, and the particles formed at a predetermined size or more are formed, and the cracking phenomenon is improved, so that the treatment at the subsequent filtration and washing step So that the tungstate compound can be produced without the conventional APT production process.

In order to control the size and shape of the precipitated tungstic acid particles, the role of the additives added in the aqueous solution of sodium tungstate will be examined in more detail. In the aqueous solution, as shown below, hydrogen peroxide acts as a solubilization and agglomeration, and the ammonium compound acts as a dispersing agent.

When the pH of the sodium tungstate aqueous solution reaches a predetermined 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.

Then, the heating and stirring for the aqueous solution are performed under a predetermined condition, and tungstic acid starts to precipitate again over time. This is because a low pH (for example, pH 14) in which tungstic acid precipitates in a sodium tungstate solution having a high pH value Tungstic acid which is irregularly generated until a value (for example, pH 1) is dissolved in several identical conditions, including the same pH period, to undergo a re-precipitation step, It can be seen as a recrystallization process.

On the other hand, when the tungstic acid is precipitated, the ammonium compound dissolved in the aqueous solution acts as a dispersant, so that the tungstic acid powders precipitate in a dispersed state so as not to be excessively aggregated with each other.

That is, the tungstic acid powder is dissolved by the hydrogen peroxide and undergoes the recrystallization process, so that the tungstic acid powders coalesce with each other to become particles capable of forming particles having a predetermined size (dissolution and coagulation of hydrogen peroxide) As the tungstic acid particles are dispersed so as not to coalesce with each other due to the surfactant effect of the ammonium compound (the dispersion of the ammonium compound), the particles can retain their shape without further agglomeration.

If the ammonium compound is not added, the tungstic acid particles formed to a certain size by the hydrogen peroxide do not maintain their shape but continue to be partially united and deformed into amorphous new particles that extend horizontally or vertically. will be. These amorphous particles are susceptible to external shocks in the subsequent step of repetitive flushing.

Conversely, if hydrogen peroxide is not added, the tungstic acid powders precipitated from the aqueous sodium tungstate solution will not dissolve and will all aggregate to form one large lump.

In other words, the dissolution and coagulation of hydrogen peroxide in the aqueous solution of sodium tungstate and the dispersing role of the ammonium compound complement each other, so that the tungstic acid powder precipitated forms tungstic acid particles having grape clusters .

When the pH of the aqueous solution reaches a predetermined value (for example, pH 1 or less) as the acidic solution as the substituent is added to the aqueous solution of sodium tungstate, tungstic acid begins to precipitate from the aqueous solution of sodium tungstate, Have amorphous tendency to coalesce with each other (see Fig. 4).

Figure 4 shows, by position, an enlargement of the tungstic acid particles produced according to the conventional wet process without the ammonium compound and hydrogen peroxide. Figs. 4A, 4C and 4D show x5000 magnification and Fig. 4B x4500 magnification. As shown in Fig. 4, the size of the particles formed by gathering the tungstic acid powder is long, some are long, and others are amorphous and irregular. This can easily break up in subsequent iterative filtration and washing steps, making subsequent processing difficult.

However, when the ammonium compound and the hydrogen peroxide are added to the sodium tungstate aqueous solution, the tungstic acid powder precipitated from the sodium tungstate aqueous solution is dissolved and coagulated by the hydrogen peroxide and is dispersed by the ammonium compound so that the precipitated tungstic acid powder is substantially uniform The particles may be aggregated and dispersed to form particles having an affinity (see FIG. 5).

FIG. 5 is an enlarged view of the tungstic acid particles prepared according to an embodiment of the present invention. 5A shows an x1000 magnification and FIG. 5B shows an x500 magnification. As shown in FIG. 5, tungstic acid particles having a grape clustering shape, which are separated one by one from each other by the complementary action of hydrogen peroxide and ammonium compounds, are formed in aqueous solution of tungstate. The tungstic acid particles having such a shape improve the cracking due to repetitive flushing at the subsequent stage, which facilitates filtration and washing, thereby making it possible to produce tungsten oxide directly without an APT production process.

Next, the step of producing tungsten oxide using the tungstic acid obtained through the above-described steps S122 to S128 will be described.

FIG. 6 is a flowchart showing the step of acquiring tungsten oxide (S130) according to an embodiment of the present invention in more detail according to time.

As shown in FIG. 6, step S130 includes a step (S132) of obtaining tungstic acid particles in a crystalline form containing water by filtering and washing the heated and stirred aqueous solution, drying the tungstic acid particles to remove water (S134), and calcining the dried tungstic acid particles (S136).

First, in step S132, the solution that has been treated until step S128 is filtered through a filtration apparatus, and acid washing and distilled water washing are repeated.

Through step (S132), tungstic acid particles in crystalline form containing water can be obtained.

The tungstic acid particles according to the embodiment of the present invention are improved in cracking of the powder due to repetitive washing and can be repeatedly washed with water smoothly.

For filtration, filter paper can be used, and the hole size of the filter paper can be determined in consideration of the size of the effective tungstic acid particles. The size of the tungstic acid particles obtained according to the embodiment of the present invention may have a size of about 10 mu m or more, so that a filter paper having a hole size of 10 mu m or less can be selectively used.

The acid solution used for pickling can be the same as the substituent solution used in step S124. This is advantageous in terms of process efficiency. For example, hydrochloric acid (HCl), nitric acid (HNO _3), at least one of sulfuric acid (H ₂ SO ₄₎ may be used.

The concentration of the acid solution used for the acid cleaning may be 1 to 10%. If the concentration of the acid solution is less than 1%, the effect of removing impurities deteriorates. If the concentration of the acid solution exceeds 10%, the concentration of the acid solution is selected within the range of 1 to 10% desirable.

Acid cleansing and distilled water cleansing can be carried out repeatedly two or more times. When the number of times of acid washing and distilled water washing is more than 5 times, the amount of distilled water used increases, so that the production cost rises and the possibility of powder cracking increases. Therefore, it is preferable not to exceed 5 times.

The thus washed tungstic acid powder is dried in a dryer to remove water (S134).

Through step S134, the moisture contained in the tungstic acid particles is removed.

The drying temperature is preferably 60 to 100 ° C. When the drying temperature is lower than 60 ° C, the drying time is long and the drying efficiency is lowered. When the drying temperature is higher than 100 ° C, it is disadvantageous that agglomeration may occur between the powders. .

Next, the tungstic acid particles obtained in the step S134 are calcined (S136).

Through the step (S136), tungsten oxide (for example, WO ₃₎ is finally obtained.

For the calcination treatment, a calcination furnace can be used in an atmospheric or vacuum atmosphere.

The calcination temperature is 400 to 1000 占 폚, and the calcination time is 1 to 6 hours. When the calcination temperature is less than 400 ° C or the calcination time is less than 1 hour, the crystal structure is not well changed from tungstic acid to tungsten oxide. If the calcination temperature is more than 1000 ° C or the calcination time is more than 6hr, The calcination temperature is selected in the range of 400 to 1000 占 폚, and the calcination time is preferably selected within the range of 1 to 6 hours.

The tungsten oxide can be obtained through the steps described above. According to the embodiment of the present invention, tungstic acid which can be easily handled in post treatment including filtration and washing can be obtained, and tungsten oxide can be produced without APT production process.

Hereinafter, embodiments in which the above steps are applied will be described together with comparative examples.

≪ Example 1 >

Sodium carbonate was mixed at a weight ratio of 1: 0.6 in a suitable amount of tungsten raw material powder, charged into a box-type electric furnace, and then hot-melted at 800 ° C for 6 hours in an air atmosphere. Then, the molten material was cooled at room temperature, dissolved in tungsten only in water, and filtered to prepare an aqueous solution of sodium tungstate (Na ₂ WO ₄ ).

10 g of ammonium chloride (NH ₄ Cl) was added to 300 ml of the aqueous sodium tungstate solution (specific gravity 1.14) prepared above and dissolved by stirring. Then, 90 ml of hydrochloric acid (HCl, 35%) and 30 ml of aqueous hydrogen peroxide (H ₂ O ₂ , 35% And the reaction was carried out for about 5 hours while maintaining the stirring speed at about 100 rpm to precipitate tungstic acid (H ₂ WO ₄ ).

Then, filter paper was put on a filtration apparatus to separate the tungstic acid and the solution, and the filtration was performed. An acid cleaning solution (HCl, 3.5%) was prepared, rinsed twice, rinsed three times with distilled water, and dried in a dryer maintained at 85 ° C. The dried tungstic acid powder was charged into a tube furnace and maintained at about 500 ° C. for 4 hours while flowing air, followed by cooling at room temperature to obtain tungsten oxide (WO ₃ ) powder.

≪ Example 2 >

An aqueous solution of sodium tungstate was prepared in the same manner as in Example 1.

After adding 10 g of ammonium chloride to 300 ml of the aqueous sodium tungstate solution (specific gravity 1.14), 90 ml of nitric acid (HNO ₃ , 60%) and 30 ml of hydrogen peroxide solution (H ₂ O ₂ , 35% Deg.] C and reacted for about 5 hours while maintaining a stirring speed of about 100 rpm to precipitate tungstic acid.

The precipitated tungstic acid was filtrated, washed, dried and calcined in the same manner as in Example 1.

≪ Example 3 >

An aqueous solution of sodium tungstate was prepared in the same manner as in Example 1.

After adding 10 g of ammonium chloride to 300 ml of the aqueous sodium tungstate solution (specific gravity 1.14), 90 ml of sulfuric acid (H ₂ SO ₄ , 99%) and 30 ml of hydrogen peroxide solution (H ₂ O ₂ , 35% The reaction was continued for about 5 hours while keeping the stirring speed at about 100 rpm, and tungstic acid was precipitated.

The precipitated tungstic acid was filtrated, washed, dried and calcined in the same manner as in Example 1.

Comparative Example 1 in which neither a dispersant nor a solubilizer was added, Comparative Example 2 in which no solubilizer was added, and Comparative Example 3 in which no dispersant was added were set as a control group for the above Examples 1 to 3, As shown in the table.

division Experimental conditions Experiment result Substituent Dispersant Solvent Na ₂ WO ₄ Specific gravity Heating temperature (℃) Heating time (hr) Stirring speed (rpm) Size (㎛) Grape cluster shape Comparative Example 1 HCl X X 1.14 40 to 45 5 100 Not measurable X Comparative Example 2 HCl NH ₄ Cl X 1.14 40 to 45 5 100 Not measurable X Comparative Example 3 HCl X H ₂ O ₂ 1.14 40 to 45 5 100 Not measurable X Experimental Example 1 HCl NH ₄ Cl H ₂ O ₂ 1.14 40 to 45 5 100 10 to 30 O Experimental Example 2 HNO ₃ NH ₄ Cl H ₂ O ₂ 1.14 40 to 45 5 100 10 to 30 O Experimental Example 3 H ₂ SO ₄ NH ₄ Cl H ₂ O ₂ 1.14 40 to 45 5 100 10 to 30 O

As can be seen from the above Table 1, when at least one of the dispersing agent and the solubilizer was not added (Comparative Examples 1 to 3), the tungstic acid particles became irregular and amorphous and the crystal structure could not be analyzed. Size analysis was impossible.

In contrast, in the case where both the dispersant containing ammonium ion and the solubilizer containing hydrogen peroxide were added (Experimental Examples 1 to 3), tungstic acid particles clustering in the form of grapevine clusters separated one by one were obtained. The same results were obtained even when nitric acid or sulfuric acid was used instead of hydrochloric acid as the substituent.

From the above results, it can be confirmed that tungstic acid particles having a desired shape can be obtained when both a dispersant and a solubilizing agent are added regardless of the kind of an acidic solution (hydrochloric acid, nitric acid, or sulfuric acid) as a substituent.

On the other hand, in order to examine the effect of the specific gravity of the sodium tungstate aqueous solution on the formation of tungstic acid particles, the specific gravity was varied (Comparative Examples 4 to 5). Except for the specific gravity of sodium tungstate.

division Experimental conditions Experiment result Substituent Dispersant Solvent Na ₂ WO ₄ Specific gravity Heating temperature (℃) Heating time (hr) Stirring speed (rpm) Size (㎛) Grape cluster shape Comparative Example 4 HNO ₃ NH ₄ Cl H ₂ O ₂ 1.05 40 to 45 5 100 1 to 10 O Comparative Example 5 HNO ₃ NH ₄ Cl H ₂ O ₂ 1.25 40 to 45 5 100 20 to 50 O

It can be seen from Table 2 that small tungstic acid particles are formed as the specific gravity of the aqueous solution of sodium tungstate is lower and larger tungstic acid particles are formed as the specific gravity is higher. In any case, grains of tungstic acid in the form of grapevine clusters that are separated one by one can be obtained. However, in order to facilitate handling of tungstic acid particles in the subsequent filtration and washing step, tungstic acid particles of 10 to 30 탆 in size The appropriate specific gravity of the aqueous sodium tungstate solution that can be formed can be selected. For example, the preferred specific gravity of the sodium tungstate aqueous solution may be greater than 1.05 and less than 1.25.

Further, in order to examine the influence of the step (S128) of heating and stirring the sodium tungstate aqueous solution on the formation of tungstic acid particles, the heating temperature, the heating time and the stirring speed were varied (Comparative Examples 6 to 10).

division Experimental conditions Experiment result Substituent Dispersant Solvent Na ₂ WO ₄ Specific gravity Heating temperature (℃) Heating time (hr) Stirring speed (rpm) Size (㎛) Grape cluster shape Comparative Example 6 HNO ₃ NH ₄ Cl H ₂ O ₂ 1.14 25 5 100 20 to 50 △ Comparative Example 7 HNO ₃ NH ₄ Cl H ₂ O ₂ 1.14 80 ~ 90 5 100 1 to 10 O Comparative Example 8 HNO ₃ NH ₄ Cl H ₂ O ₂ 1.14 40 to 45 10 100 10 to 30 O Comparative Example 9 HNO ₃ NH ₄ Cl H ₂ O ₂ 1.14 40 to 45 5 X 20 to 80 △ Comparative Example 10 HNO ₃ NH ₄ Cl H ₂ O ₂ 1.14 40 to 45 5 250 1 to 20 O

Step S128 corresponds to heating and stirring the aqueous solution so that tungstic acid can be precipitated from the sodium tungstate aqueous solution.

From Table 3, it can be seen that, in the case of Comparative Example 6 in which the heating temperature in Step S128 is very low, the size of the precipitated particles becomes large, but it is difficult to form grains having a desired grape shape. On the other hand, in the case of Comparative Example 7 in which the heating temperature in the step S128 is very high, it can be confirmed that the size of the precipitated particles is small, which is expected to make filtration and flushing as the subsequent steps difficult. Therefore, it can be confirmed that the heating temperature in step S128 is suitably selected in the range of 30 to 75 占 폚.

Comparative Example 8 shows that grains having a desired grape cluster shape can be formed even if the heating time in step S128 is long. Since the recovery rate will be lower as the heating time is shortened, the appropriate heating time can be selected. As an example, the heating time in step S128 can be selected in the range of 1 to 6 hours.

Comparative Example 9 shows that when the stirring speed in Step S128 is very low, the size of the precipitated particles becomes very large and has an irregular shape. On the other hand, Comparative Example 10 shows that when the stirring speed in Step S128 is very high, the size of the precipitated particles becomes small. The fine particle size is expected to make subsequent filtration and washing difficult. Therefore, it can be confirmed that the stirring speed in step S128 is preferably selected in the range of 60 to 200 rpm.

Further, in order to examine the influence of the kind of the dispersing agent as the first additive and the kind of the dissolving agent as the second additive on the formation of the tungstic acid particle, the anion portion of the ammonium compound was changed (Experimental Examples 4 to 12) Instead, experiments were conducted using hydrofluoric acid (Experimental Example 13). The experimental conditions except for the dispersing agent and the dissolving agent were all set as in Experimental Example 2.

division Experimental conditions Experiment result Substituent Dispersant Solvent Na ₂ WO ₄ Specific gravity Heating temperature (℃) Heating time (hr) Stirring speed (rpm) Size (㎛) Grape cluster shape Experimental Example 4 HNO ₃ NH ₄ NO ₃ H ₂ O ₂ 1.14 40 to 45 5 100 10 to 30 O Experimental Example 5 HNO ₃ (NH _{4) 2} CO ₃ H ₂ O ₂ 1.14 40 to 45 5 100 10 to 30 O Experimental Example 6 HNO ₃ NH ₄ HCO ₃ H ₂ O ₂ 1.14 40 to 45 5 100 10 to 30 O Experimental Example 7 HNO ₃ (NH _{4) 2} SO ₄ H ₂ O ₂ 1.14 40 to 45 5 100 10 to 30 O Experimental Example 8 HNO ₃ NH ₄ F H ₂ O ₂ 1.14 40 to 45 5 100 10 to 30 O Experimental Example 9 HNO _{3 (NH 4) 2 C 2 O} 4 H ₂ O ₂ 1.14 40 to 45 5 100 10 to 30 O Experimental Example 10 HNO ₃ NH ₄ CH ₃ CO ₂ H ₂ O ₂ 1.14 40 to 45 5 100 10 to 30 O Experimental Example 11 HNO ₃ (NH ₄₎ H ₂ PO ₄ H ₂ O ₂ 1.14 40 to 45 5 100 10 to 30 O Experimental Example 12 HNO ₃ (NH _{4) 2} HPO ₄ H ₂ O ₂ 1.14 40 to 45 5 100 10 to 30 O Experimental Example 13 HNO ₃ NH ₄ Cl HF 1.14 40 to 45 5 100 10 to 30 O

From the above Table 4, it can be seen that the dispersant containing ammonium ions is composed of ammonium nitrate (NH ₄ NO ₃ ) of Experimental Example 4, ammonium carbonate ((NH ₄ ) ₂ CO ₃ ) of Experimental Example 5, ammonium bicarbonate ₄ HCO _3), example 7 of ammonium sulfate _{((NH 4) 2 SO 4} ), ammonium fluoride in experimental example 8 (NH ₄ F), of oxalic acid in experimental example 9 ammonium _{((NH 4) 2 C 2} O 4) (NH ₄ CH ₃ CO ₂ ) of Experimental Example 10, ammonium monophosphate (NH ₄ H ₂ PO ₄ ) of Experimental Example 11, and ammonium phosphate ((NH ₄ ) ₂ HPO ₄ of Experimental Example 12) It is possible to obtain tungstic acid particles having a desired shape.

It is also shown that tungstic acid particles having a desired shape can be obtained in the same manner as in Experimental Example 13 using hydrofluoric acid instead of hydrogen peroxide as the solubilizer.

According to the embodiment of the present invention, the tungstic acid particles each having a predetermined size or more are formed, and the cracking phenomenon is improved, so that the treatment is easy in the subsequent filtration and washing steps, and the tungstate compound Can be manufactured at low cost.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- And various modifications and changes may be made thereto by those skilled in the art to which the present invention pertains. Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (16)

Introducing an acid solution into the tungstate aqueous solution to precipitate tungstic acid; And
And obtaining tungsten oxide from the tungstic acid,
Wherein the precipitation step comprises using a first additive comprising an ammonium compound and a second additive comprising at least one of hydrogen peroxide and hydrofluoric acid,
Wherein the step of precipitating comprises:
Adding the first additive to the aqueous solution before adding the acidic solution,
And adding the second additive to the aqueous solution after the acidic solution is added. The method according to claim 1,
The first additive is ammonium chloride (NH ₄ Cl), ammonium nitrate (NH ₄ NO _3), ammonium carbonate ((NH _{4) 2} CO _3), ammonium bicarbonate (NH ₄ HCO _3), ammonium sulfate ((NH _{4) 2} SO _4), ammonium fluoride (NH ₄ F), ammonium oxalate _{((NH 4) 2 C 2} O 4), ammonium acetate _{(NH 4 CH 3 CO 2)} , phosphate, ammonium (NH ₄ H ₂ PO _4), and the ammonium phosphate _{((NH 4) 2 HPO 4} ) at least one of tungsten oxide production method that includes of. The method according to claim 1,
Wherein the second additive acts as a dissolving agent for dissolving the precipitated tungstic acid so that particles formed by the precipitated tungstic acid do not exceed a predetermined size. The method according to claim 1,
Wherein the first additive acts as a dispersing agent for dispersing the particles together so that the particles formed by the precipitated tungstic acid have a definite shape. The method according to claim 1,
The acidic solution is hydrochloric acid (HCl), nitric acid (HNO _3), sulfuric acid (H ₂ SO ₄₎ at least a tungsten oxide production method which includes one of. The method according to claim 1,
Wherein the tungstate comprises sodium tungstate (Na ₂ WO ₄ ). delete The method according to claim 1,
Wherein the step of precipitating comprises:
Further comprising heating and stirring the aqueous solution after adding the second additive. 9. The method of claim 8,
The specific gravity of the tungstate aqueous solution is more than 1.05 but less than 1.25,
20 to 80 ml of the acid solution is added 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,
Wherein the second additive is added in an amount of 1 to 10 ml per 100 ml of the tungstate aqueous solution. 10. The method of claim 9,
Wherein the heating and stirring are performed at a rate of 60 to 200 rpm for 1 to 6 hours at a temperature in the range of 30 to 75 占 폚. 9. The method of claim 8,
Wherein the acquiring comprises:
Filtering and washing the heated and stirred aqueous solution to obtain the crystalline tungstic acid containing water;
Drying the obtained tungstic acid to remove the water, and
And calcining the dried tungstic acid. The method according to claim 1,
Providing a tungstate aqueous solution using a tungsten source and a carbonate. 13. The method of claim 12,
Tungsten oxide production method including the carbonate is sodium carbonate (Na ₂ CO _3). 13. The method of claim 12,
Wherein the providing step comprises:
Mixing the tungsten raw material and the carbonate and melting them at a high temperature,
Cooling the molten mixture and then adding water to elute the tungstate aqueous solution. The method according to claim 1,
Wherein the particles of the precipitated tungstic acid each have a diameter of 10 to 30 占 퐉. A tungsten oxide produced by the process according to any one of claims 1 to 6 and 8 to 15.

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