KR20190074745A - Method for recovering valuable metals from denitrification waste catalysts - Google Patents

Abstract

The present invention relates to a method for recovering valuable metal contained in a denitrification waste catalyst and, more specifically, to a method for recovering valuable metal contained in a denitrifiaction waste catalyst, comprising the following steps of: grinding valuable metal such as tungsten (WO_3) and vanadium (V_2O_5) contained in the denitrification waste catalyst into sodium hydroxide (NaOH) and fine particles to roast and leach the valuable metal; and concentrating sodium tungstate (Na_2WO_4) and sodium vanadate (NaVO_3) in a vacuum evaporation manner for crystallization. Therefore, the valuable metal can be recovered in quantity.

Description

[0001] The present invention relates to a method for recovering valuable metals from denitrification waste catalysts,

The present invention relates to a method for recovering valuable metals contained in a denitrification catalyst, and more particularly, to a method for recovering valuable metals such as tungsten and vanadium contained in a denitrification catalyst, which is a waste of an NO x removal catalyst, To a method for recovering valuable metals contained in a denitrification catalyst which is roasted with sodium hydroxide or sodium carbonate (Na ₂ CO ₃ ) for leaching and recovered in large quantities.

Fossil fuels, coal, petroleum, natural gas is a combustion gas generated during combustion is contained a lot of nitrogen oxides (NO, NO _2, etc. known as NOx). As the use of fossil fuels increases, the amount of nitrogen oxides generated is further increased, which is a typical harmful substance causing problems such as fine dust, acid rain, and photochemical smog.

This, and the use of a denitration catalyst to reduce the emissions in the atmosphere of nitrogen oxides (NO, NO _2, etc. known as NOx) air pollutants, the mechanism of by injecting ammonia (NH ₃₎ for combustion gases fitted NOx removal catalyst NO _x and NH ₃ are chemically reacted on the surface of the catalyst in the SCR reactor and converted into nitrogen molecules (N ₂ ) and water vapor molecules (H ₂ O) the concentration of NO, NO _2, etc. known as NOx) in 250 ~ 300ppm of the first generation is performed is a role lowers to below 140ppm (90ppm from 2018).

However, there is an environmental problem that a denitration catalyst such as the SCR catalyst is used in a large amount in a device using fossil fuel, because a denitration catalyst is used for about 20,000 hours and secondary waste is generated .

In recent years, tungsten (WO ₃ = 7 to 8%), vanadium (V ₂ O ₅ = 1 to 2%), titanium (TiO ₂ = 70 to 72% ) Are reclaimed to minimize secondary wastes, and many technologies have been proposed.

Korean Patent No. 10-1281579 (Feb. 23, 2013) discloses a method for leaching valuable metals contained in a denitrification catalyst using roasting and water leaching.

(A) mixing an denitration waste catalyst containing vanadium (V) and tungsten (W) in the form of oxides with an alkali metal compound to form a mixture, wherein the alkali Mixing 15 to 30% by weight of a metal compound;

(b) roasting said mixture to produce a roast product comprising sodium vanadate (NaVO ₃ ) and sodium tungstate (Na ₂ WO ₄ ); And

(c) subjecting the endosperm production product to water so that sodium vanadate and sodium tungstate are water-leached in the form of vanadium acid ions (VO ₃ ^- ) and tungstate ions (WO ₄ ^2- ) do.

Here, the alkali metal compound is composed of sodium carbonate (Na ₂ CO ₃ ) or sodium hydroxide (NaOH), and the step (b) is performed at 800 to 900 ° C.

However, in the above-mentioned prior art, only a small amount of the denitrification catalyst is introduced into the process due to the volume of the denitrification catalyst that is input during the step (a) (mixing process), so that the large amount of sodium vanadate and sodium tungstate This was a difficult problem.

In addition, in the above-mentioned prior art, although the leaching efficiency is increased according to the weight ratio and the temperature of the water when the product is introduced into the water of the end product in the step (c) (water leaching step) there is a problem that it takes more time to perform the step c).

It is an object of the present invention to improve the chemical reaction between the denitrification catalyst and sodium hydroxide by pulverizing it into fine particles before roasting, and it is possible to increase the amount of sodium tungstate and sodium vanadate It is possible to increase the dispersion efficiency and the leaching rate by circulating and rotating the water so that the contained powder is prevented from being aggregated when dissolved in water, and the sodium tungstate and sodium vanadate can be stably recovered from a large amount of the denitrification- The present invention provides a method for recovering valuable metals contained in a denitrification catalyst.

In order to accomplish the above object, the present invention provides a method for recovering valuable metals contained in a denitrification catalyst, comprising the steps of removing tungsten (WO ₃ ) and vanadium (Fe ₃ O ₃ ) contained in a denitrification catalyst used for reducing harmful substances generated during fossil fuel combustion V ₂ O ₅ ), the mixture of 100 wt% of denitrification catalyst and 20 to 30 wt% of sodium hydroxide (NaOH) is crushed and crushed on the inner wall of the crusher to be spheroidized A pulverizing step of pulverizing; A collecting transfer step of collecting, in a cyclone, a pulverized product having a size of 500 to 1000 meshes in the pulverized product pulverized in the pulverizing step; A mixing step of spraying 10 to 15% by weight of water on 100% by weight of the pulverized material collected in the collecting and transferring step to form sodium hydroxide (NaOH) in a blender so as to absorb moisture; In the mixing step, tungsten (WO ₃ ) and vanadium (V ₂ O ₅ ) contained in the pulverized product react with sodium hydroxide (NaOH), so that sodium tungstate (Na ₂ WO ₄ ) date (NaVO _3), and in that the roasting phase is stirred and roasted in a rotary kiln of 830 ~ 870 ℃ temperature conversion; A second grinding step of grinding the roasted product produced in the roasting step into a powder having a size of less than 500 mesh; A step of leaching the powder pulverized in the second pulverization step into water at a temperature of 60 to 70 캜 to leach sodium tungstate (Na ₂ WO ₄ ) and sodium vanadate (NaVO ₃ ) into ionized solution and residue; A solution separation step of separating the solution and the residue of the leaching step into compressed air of a filter press; And crystallizing sodium tungstate (Na ₂ WO ₄ ) and sodium vanadate (NaVO ₃ ) contained in the solution separated in the solution separation step, followed by crystallization in an evaporator.

The leaching step is characterized in that the flow impeller of the leaching vessel is rotated at a high speed such that the water is circulated and rotated when the powder is introduced.

Wherein the crystallization is performed by a vacuum evaporation method such that sodium tungstate (Na ₂ WO ₄ ) and sodium vanadate (NaVO ₃ ) are contained in an amount of 5 to 7 wt% in 100 wt% of the concentrate when the solution is converted into a concentrate Wow; And a concentrated liquid crystallization step of crystallizing the concentrated liquid into an evaporator at 150 to 200 ° C.

In the concentration step, 30 g of ammonium chloride (NH ₄ Cl) is dissolved in 1,000 ml of the concentrate, 500 ml of 40% by weight hydrochloric acid and 100 ml of hydrogen peroxide at a concentration of 40% by weight are mixed, (H ₂ WO ₄ ) to crystallize and separate the tungstate (H ₂ WO ₄ ).

And an air transfer step of transferring air from the powder discharge port to the blender to prevent the pulverized product from being scattered is provided in the blending step.

And the roasting time during which the pulverized product is roasted in the rotary kiln in the roasting step is 3 to 4 hours.

The pulverizing step may include a pulverizing step of transferring particles larger than 500 to 1000 mesh size in the pulverized product to the impeller end of the pulverizer to re-pulverize the pulverized product.

As described above, the method for recovering valuable metals contained in the denitrification catalyst according to the present invention has the following effects.

First, by pulverizing the denitrification catalyst and sodium hydroxide into 500 to 1000 mesh, Na ⁺ ions of sodium hydroxide can be contacted with tungsten (WO ₃ ) and vanadium (V ₂ O ₅ ) of the denitrification waste catalyst during mixing and roasting The surface area is enlarged to increase the leaching rate,

Second, tungsten (WO ₃₎ and vanadium (V ₂ O ₅₎ is by stirring rotation and roasting in a rotary kiln to produce a tungsten oxide and vanadium oxide reacts with sodium hydroxide and the tungsten (WO ₃₎ and vanadium (V ₂ O ₅ ) The chemical reaction of sodium hydroxide reacts evenly and the leaching rate can be increased,

Third, the powder containing tungsten oxide and vanadium oxide is introduced into the water by vacuum suction force, and the water is strongly circulated and rotated by the rotation of the impeller of the leaching vessel, so that the tungsten oxide and vanadium oxide are aggregated And the leaching time can be shortened,

Fourth, a solution in which tungsten oxide and vanadium oxide are dissolved in water is concentrated and concentrated by an evaporator of a vacuum concentration method, whereby a large amount can be treated with less power than the conventional pressure heating method, and productivity is improved.

FIG. 1 is a view for explaining a leaching method for a valuable metal contained in a denitrification catalyst using roasting and water leaching according to the prior art,
2 is a view for explaining a method for recovering a valuable metal contained in a denitrification catalyst according to the present invention,
3 is a view for explaining the crystallization step of the method for recovering valuable metals according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method for recovering valuable metals contained in a denitrification catalyst according to the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIGS. 2 to 3, the method for recovering valuable metals contained in the denitrification catalyst according to the present invention is a method for recovering tungsten (WO) contained in a denitrification catalyst used for reducing harmful substances generated during combustion of fossil fuel ₃ ) and vanadium (V ₂ O ₅ ) is withdrawn by leaching out a mixture of 100 wt% of denitrification catalyst and 20 to 30 wt% of sodium hydroxide (NaOH) in the crusher, A crushing step (S10) of crushing, spheronizing and crushing each other; A collecting transfer step (S20) of collecting the pulverized material having a size of 500 to 1000 meshes in the cyclone in the pulverizing step (S10); A mixing step (S30) of spraying 10 to 15% by weight of water on 100% by weight of the pulverized material collected in the collecting and transferring step (S20) and mixing the sodium hydroxide (NaOH) in a blender to absorb moisture; (WO ₃ ) and vanadium (V ₂ O ₅ ) contained in the pulverized product react with sodium hydroxide (NaOH) to form sodium tungstate (Na ₂ WO ₄ ) which is easily dissolved in water in the mixing step (S30) and sodium vanadate (NaVO ₃₎ roasting step is stirred and roasted in a rotary kiln of 830 ~ 870 ℃ temperature to convert to (S40) and; A second grinding step (S50) of grinding the roasted product produced in the roasting step (S40) with a powder having a size smaller than 500 mesh; The second charged into the the powder pulverized in the pulverizing step (S50) in water of 60 ~ 70 ℃ sodium tungstate (Na ₂ WO ₄₎ and sodium vanadate (NaVO ₃₎ is leached to leach into the ionized solution and the residues Step S60; A solution separation step (S70) of separating the solution and the residue of the leaching step (S60) into compressed air of a filter press; After concentration of the solution and the solution separated in the separation step (S70) in the evaporator of sodium tungstate (Na ₂ WO ₄₎ and sodium vanadate (NaVO ₃₎ a crystallization step (S80) as a crystallizing; consists of.

In this case, sodium carbonate (Na ₂ CO ₃ ) may be used instead of sodium hydroxide (Na ₂ CO ₃ ). In the grinding step (S 10), the impeller of the pulverizer is rotated at a high speed so that air and pulverized material forced in the pulverizer (50 to 20 mu m) in size by friction with each other and pulverized into ultrafine particles having a size of 500 to 1000 mesh (50 to 20 mu m) It becomes easy to crush.

Further, as the pulverized product becomes spheroidized, the surface area becomes wider, and tungsten (WO ₃ ) and vanadium (V ₂ O ₅ ) react with Na + of sodium hydroxide (NaOH) to increase the leaching rate. When the pulverized product is pulverized with ultrafine particles having a size of 600 mesh (40 μm or less), the leaching rate is as high as about 85%.

Meanwhile, in the leaching step (S60), the flow impeller of the leaching vessel is rotated at a high speed so that the water is circulated and rotated when the powder is introduced. The rotation of the flow impeller circulates the water and generates a suction force for sucking the powder, so that the powder is dispersed at the same time when the powder contacts with the water, thereby preventing the aggregation phenomenon. As a result, the leaching rate is also increased.

Also, the solution separating step (S70) is filtered and various insoluble metal debris, such as sodium tungstate (Na ₂ WO ₄₎ and sodium vanadate (NaVO ₃₎ and titanium (TiO ₂₎ was dissolved in the leaching step (S60) which is then separated by filtration.

In the crystallization step S80, the concentration of the concentrate such that sodium tungstate (Na ₂ WO ₄ ) and sodium vanadate (NaVO ₃ ) are contained in an amount of 5 to 7 wt% is added to 100 wt% of the concentrate when the solution is converted into a concentrate Step S81; And a concentrate crystallization step (S82) of crystallizing the concentrated liquid into an evaporator at 150 to 200 deg.

In the crystallization step (S80), about 90 kW of electricity is consumed in order to crystallize one ton of the solution by performing the concentrate crystallization step (S82) through the concentration step (S81) using the evaporator of the vacuum evaporation type. This is very economical as compared with the conventional pressure heating method which consumes about 1000 kW of power.

In addition, the crystallization step (S80) is, and increase the quality of tungsten (WO ₃₎ than the conventional method. That is, the conventional crystallization method has a problem in that calcium chloride (CaCl) is added to crystallize and precipitate, so that a large amount of calcium (Ca) remains together and the quality of tungsten (WO3) drops.

In the concentration step S81, 30 g of ammonium chloride (NH ₄ Cl) was dissolved in 1,000 ml of the concentrate, and 500 ml of hydrochloric acid (HCL) at a concentration of 40% by weight and hydrogen peroxide (H ₂ O ₂ ) (S85) for separating and crystallizing the tungstate (H ₂ WO ₄ ) by reacting the mixture at 40 to 50 ° C. for 3 to 4 hours.

Here, the ammonium chloride (NH ₄ Cl) serves to disperse the concentrate. The hydrogen peroxide (H ₂ O ₂ , 40%) acts as a complement to the ammonium chloride (NH ₄ Cl) by dissolving and coagulating the concentrate. In addition, the hydrochloric acid (HCL) lowers the pH of the concentrate to PH2 or lower, thereby extracting tungstate (H2WO4) from the concentrate. At this time, the quality of the tungstate (H2WO4) is extracted with WO ₃ = 80% level.

Meanwhile, in the collecting transfer step S20, an air transfer step S21 for transferring air from the powder discharge port to the blender is provided so as to prevent the pulverized product from being scattered.

That is, the pulverized material collected in the cyclone in the collecting transfer step (S20) is easily scattered in a size of 500 to 1000 mesh, thereby reducing the loss of the pulverized material due to transportation and transportation from the pulverization to the blending machine, Dust generation can be reduced.

Meanwhile, in the roasting step (S40), the pulverized product is roasted in the rotary kiln for 3 to 4 hours of roasting time. The roasting time of 3 hours or less is less than the roasting rate, and the roasting time of 4 hours or more is no longer increased in leaching rate, so that roasting time of 3 to 4 hours is preferable. The chemical reaction that occurs during roasting is expressed as follows.

WO ₃ + ₂ NaOH = Na ₂ WO ₄ (sodium tungstate) + 2H ₂ O

V ₂ O ₅ + ₂ NaOH = 2NAVO ₃ (sodium vanadate) + 2H ₂ O

In the grinding step (S10), a re-pulverization step (S11) of transferring particles larger than 500 to 1000 mesh size of the pulverized product to the impeller end of the pulverizer and re-pulverizing the pulverized product is provided. That is, since the size of the pulverized particles influences the leaching rate of sodium tungstate (sodium tungstate) and sodium vanadate (sodium vanadate), pulverization with ultrafine particles increases the contact area, It becomes easy.

The operation of the method for recovering valuable metals contained in the denitrification catalyst according to the present invention having the above structure is as follows.

In the method for recovering valuable metals contained in the denitrification catalyst of the present invention, any one of sodium hydroxide (NaOH) or sodium carbonate (Na ₂ CO ₃ ) is mixed with the denitrification catalyst and pulverized into spherical ultra-fine particles. The ultrafine particles are roasted in a rotary kiln to produce a boiled product containing sodium tungstate (Na ₂ WO ₄ ) and sodium vanadate (NAVO ₃ ) which are easily soluble in water.

Here, the denitrification waste catalyst contains 7 to 8 wt% of tungsten (WO ₃ ), 1 to 2 wt% of vanadium (V ₂ O ₅ ), and about 70 to 72 wt% of titanium (TiO ₂ ) (WO ₃ ) and vanadium (V ₂ O ₅ ) are mixed with sodium hydroxide (NaOH) and roasted to convert into sodium tungstate (Na ₂ WO ₄ ) and sodium vanadate (NAVO ₃ ) It is eluted and filtered to recover a predetermined product.

First, 100% by weight of denitrification catalyst and 20 to 30% by weight of sodium hydroxide (NaOH) are mixed in a pulverizing step (S10), and they are pulverized in a pulverizer so that the denitrification catalyst and sodium hydroxide (NaOH) . At this time, the impeller inside the pulverizer is rotated at a high speed. In the collecting transfer step S20, only fine particles having a predetermined size of 500 to 1000 mesh are collected in the cyclone in the pulverizing step (S10) To the air conditioner to the blender, thereby preventing the fine particles from being scattered.

In the compounding step (S30), water is sprayed in the form of spray so that moisture is adsorbed to the sodium hydroxide (NaOH), and sodium hydroxide (NaOH) dissolved in water is added to the denitrification catalyst to remove tungsten (WO ₃ ) and vanadium ₂ O ₅ ) for 0.5 to 1 hour to mix well.

In the roasting step S40, the mixed compound of the mixing step S30 is mixed with tungsten (WO ₃ ) and vanadium (V ₂ O ₅ ) with sodium hydroxide (NaOH) to form sodium tungstate (Na ₂ WO ₄ ) vanadate (NaVO ₃₎ is produced in the rotary kiln so that the stirring of 830 ~ 870 ℃ temperature, and is calcined.

At this time, the roasted product in the roasting step S40 is cured and then subjected to a second grinding step (S50). In the second grinding step (S50), the roasted product is once again pulverized with a powder smaller than 500 mesh Further crushing facilitates leaching.

Then, the leaching step (S60) in the 60 to circulate water of 70 ℃ temperature and charged into the the powder pulverized in the roasting step (S40) in the water of sodium tungstate (Na ₂ WO ₄₎ and sodium vanadate ( NaVO ₃ ) dissolved in the solution is obtained.

At this time, the water is circulated and rotated to prevent the powder from being aggregated. In addition, circulation of the water reduces the dispersion time of the powder, thereby increasing the dispersion efficiency and the leaching rate. In the leaching step (S60), the amount of hot water used is reduced by about 20%, and the leaching time is shortened by about 50% or more in about 30 minutes.

Meanwhile, in the solution separating step (S70), the slurry containing the solution and the residue is transferred to the filter press by a hydraulic pump, and the compressed air of the filter press separates the slurry into the solution and the residue.

Finally, the sodium tungstate (Na ₂ WO ₄₎ and sodium vanadate (NaVO ₃₎ a concentration step (S81) of condensed or concentrated using steam as the vacuum evaporation method included in the solution in the crystallization step (S80) And crystallized in an evaporator at a temperature of 150 to 200 ° C.

Therefore, in the leaching step S60 of the present invention, the amount of hot water used and the leaching time are reduced, and in the crystallization step S80, sodium tungstate (Na ₂ WO ₄ ) and sodium vanadate (NaVO ₃ ) It is possible to crystallize the crystals into an amorphous state, thereby improving the economical efficiency.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims and their equivalents. Of course, such modifications are within the scope of the claims.

Description of the Related Art
S10: Grinding step S11: Re-grinding step
S20: collecting transfer step S21: air transfer step
S30: mixing step S40: roasting step
S50: Second crushing step S60: Leaching step
S70: solution separation step S80: crystallization step
S81: Concentration step S82: Concentrate crystallization step
S85: Tungstate separation step

Claims (7)

(WO ₃ ) and vanadium (V ₂ O ₅ ) contained in the denitrification catalyst used to reduce harmful substances generated during combustion of fossil fuel,
(S10) in which a mixture of 100 wt% of denitrification catalyst and 20 to 30 wt% of sodium hydroxide (NaOH) is rubbed together on the inner wall at the time of crushing in the crusher to be spheroidized and crushed;
A collecting transfer step (S20) of collecting and transporting pulverized material having a size of 500 to 1000 meshes in the cyclone in the crushing step (S10);
A mixing step (S30) of spraying 10 to 15% by weight of water on 100% by weight of the pulverized material collected in the collecting and transferring step (S20) and mixing the sodium hydroxide (NaOH) in a blender to absorb moisture;
(WO ₃ ) and vanadium (V ₂ O ₅ ) contained in the pulverized product react with sodium hydroxide (NaOH) to form sodium tungstate (Na ₂ WO ₄ ) which is easily dissolved in water in the mixing step (S30) and sodium vanadate (NaVO ₃₎ roasting step is stirred and roasted in a rotary kiln of 830 ~ 870 ℃ temperature to convert to (S40) and;
A second grinding step (S50) of grinding the roasted product produced in the roasting step (S40) with a powder having a size smaller than 500 mesh;
The second charged into the the powder pulverized in the pulverizing step (S50) in water of 60 ~ 70 ℃ sodium tungstate (Na ₂ WO ₄₎ and sodium vanadate (NaVO ₃₎ is leached to leach into the ionized solution and the residues Step S60;
A solution separation step (S70) of separating the solution and the residue of the leaching step (S60) into compressed air of a filter press;
Characterized in that consisting of; the solution contained in the solution separated in the separation step (S70) of sodium tungstate (Na ₂ WO ₄₎ and sodium vanadate (NaVO ₃₎ that after the crystallization step (S80) crystallizing from the evaporator concentrate the Wherein the denitrification catalyst comprises a denitrification catalyst. The method according to claim 1,
The leaching step (S60)
Wherein the flow impeller of the leaching vessel is rotated at a high speed such that the water is circulated and rotated when the powder is introduced. The method according to claim 1,
The crystallization step (S80)
A concentrating step (S81) of concentrating the concentrated solution by vacuum evaporation so that sodium tungstate (Na ₂ WO ₄ ) and sodium vanadate (NaVO ₃ ) are contained in an amount of 5 to 7 wt% ;
And crystallizing the concentrate in an evaporator at 150 to 200 DEG C to crystallize the concentrate (S82). The method of claim 3,
In the concentration step S81
30 g of ammonium chloride (NH ₄ Cl) was dissolved in 1,000 ml of the concentrate, 500 ml of hydrochloric acid having a concentration of 40% by weight and 100 ml of hydrogen peroxide having a concentration of 40% by weight were mixed and reacted at 40 to 50 ° C for 3 to 4 hours The method for recovering valuable metals as recited in claim 1, further comprising a tungstate separation step (S85) for crystallizing and separating the tungstate (H ₂ WO ₄ ). The method according to claim 1,
In the collecting transfer step S20
(S21) for transferring air from the powder discharge port to the blender so as to prevent the pulverized product from being scattered. The method according to claim 1,
Wherein the roasting time during which the pulverized product is roasted in the rotary kiln in the roasting step (S40) is 3 to 4 hours. The method according to claim 1,
In the grinding step (S10)
And a re-pulverizing step (S11) of transferring particles larger than the size of 500 to 1000 mesh in the pulverized product to the impeller end of the pulverizer to re-pulverize the pulverized product.

Images