TWI468524B - Recovery of vanadium and tungsten from waste selective catalytic reduction catalyst - Google Patents

Description

Method for recovering vanadium and tungsten from waste selective catalytic reduction catalyst

The invention relates to a method for recovering vanadium and tungsten from a waste selective catalytic reduction catalyst, in particular to a method for using an anion exchange resin in combination to recover vanadium and tungsten in a waste selective catalytic reduction catalyst.

Selective catalytic reduction (SCR) is currently the mainstream technology for the treatment of air pollutant nitrogen oxides (NO _x ). The catalyst used in the selective catalytic reduction method (hereinafter referred to as SCR catalyst) includes a carrier made of ceramics, and an active material such as tungsten oxide (WO ₃ ) or vanadium oxide (V ₂ O ₅ ). . After use, the SCR catalyst can be reused and become a waste SCR catalyst. The waste SCR catalyst contains heavy metals such as vanadium and tungsten. If it is disposed of at will, heavy metals will pollute the environment and cause more environmental pollution problems. If the metals such as vanadium and tungsten in the discarded SCR catalyst cannot be recovered, it is also a waste of earth resources. Therefore, how to separate vanadium and tungsten from waste SCR catalyst, to avoid vanadium and tungsten polluting the environment and to recycle and reuse these metals is also an important subject for research in this field.

Taiwan Patent No. I295691 discloses a method for regenerating waste denitrification catalyst resources, which is to separate vanadium and tungsten from waste denitrification catalyst: the following steps are included: grinding waste denitrification catalyst to a size of 50 mesh, adding and removing waste The same amount of Na ₂ CO ₃ as the nitrate catalyst is mixed with the waste denitration catalyst, calcined at 800 ° C for 2 hours, and the calcined solid product is impregnated with water to obtain an impregnation liquid containing vanadium and tungsten metal; After adding sodium sulfite to the liquid and adjusting the pH of the immersion liquid to 0.5 with sulfuric acid, the immersion liquid is extracted with a solvent to extract the tungsten metal in the immersion liquid to the oil phase, and the vanadium metal remains in the water phase to obtain a An oil phase containing a tungsten metal and an aqueous phase containing a vanadium metal. The tungsten metal-containing oil phase is extracted by back extraction, and the tungsten metal is back-extracted to the aqueous phase to obtain an aqueous phase containing tungsten metal. Finally, the aqueous phase of the vanadium-containing metal is crystallized to form NH ₄ VO ₃ by crystallization, and the aqueous phase containing the tungsten metal is precipitated by precipitation to precipitate NH ₄ WO ₄ . 3H ₂ O.

Although the method of the Taiwan patent case can achieve a good recovery rate of tungsten, but the operation steps are cumbersome (requires extraction and then back extraction), the extractant [trioctylamine] used is costly, complicated and costly. The recycling method will reduce the willingness of relevant industry to recycle vanadium and tungsten in the waste SCR catalyst, and even cause the industry to discard the waste SCR catalyst and pollute the environment. Moreover, the method further needs to additionally treat the extraction waste liquid, and the extracting agent used in the method is slightly soluble in the water phase, and if the time of extraction and back extraction is improperly controlled, the extracting agent is slightly soluble in water. The increase in the difficulty of processing the extracted waste liquid not only increases the cost of processing the extracted waste liquid, but also causes environmental pollution if the extraction waste liquid is improperly disposed.

From the above, the selective catalytic reduction method can effectively treat nitrogen. Oxide is of great help to the prevention and control of air pollution. However, if the waste SCR catalyst is improperly disposed, it will cause environmental pollution and waste of earth resources. Therefore, if a metal with high balance can be developed ( Vanadium and tungsten) can effectively and comprehensively protect the environment by recovering vanadium and tungsten from waste SCR catalysts with low recovery rate, simple steps and no environmental pollution.

Accordingly, it is an object of the present invention to provide a process for recovering vanadium and tungsten from a spent selective catalytic reduction catalyst which is effective in recovering vanadium and tungsten from waste SCR catalysts without contaminating the environment.

Therefore, the method for recovering vanadium and tungsten from the waste selective catalytic reduction catalyst comprises: providing a waste selective catalytic reduction catalyst comprising a vanadium source and a tungsten source; a pretreatment step comprising a baking step And a immersing step: mixing the waste selective catalytic reduction catalyst with a calcining agent and calcining to form a calcined selective catalytic reduction catalyst, wherein the vanadium source and the tungsten source are respectively Reacting with the calcining agent to form a vanadium salt and a tungsten salt, and the impregnating step is: immersing the calcined selective catalytic reduction catalyst in a vanadium salt and tungsten formed by dissolving the roasting treatment a salt liquid to dissolve the vanadium salt and the tungsten salt to form an immersion liquid; an impurity removing step to remove impurities in the immersion liquid to form a purified immersion liquid; and an ion exchange step, the purified pH range adjustment of the immersion liquid From 1 to 3, a liquid to be separated is formed, and the vanadium salt and the tungsten salt in the liquid to be separated are separated by an anion exchange resin to obtain a vanadium-containing solution, and an anion exchange resin containing tungsten.

The effect of the invention is that the vanadium and tungsten are successfully separated and recovered from the discarded SCR catalyst by sequentially performing the calcination step, the impregnation step, the impurity removal step and the ion exchange step, and the ion exchange step can be used Improve the recovery rate of vanadium and tungsten without causing environmental pollution.

The contents of the present invention will be described in detail below:

In the present invention, the selective catalytic reduction catalyst (hereinafter referred to as SCR catalyst) used is not particularly limited, and both existing and commercially available SCR catalysts are suitable for the method of the present invention. In the SCR catalyst, the vanadium source is more specifically a vanadium oxide, such as V ₂ O ₅ , more specifically a tungsten oxide, such as WO ₃ .

The following is a detailed description of each processing step:

Pre-Processing Steps

The pretreatment step includes a calcination step and an impregnation step after the calcination step. If the calcination step is not carried out first, the waste SCR catalyst may be directly subjected to an impregnation step to dissolve the vanadium source and the tungsten source, but the impregnation efficiency is low. In this case, high temperature and high pressure equipment is required and used. The concentration of acid or lye can achieve the desired impregnation efficiency. The method of the invention performs the calcination step before the impregnation step, and in addition to obtaining excellent impregnation efficiency, it is not necessary to use high temperature and high pressure equipment and high concentration acid or alkali solution.

[baking step]

The baking step is first to treat the waste SCR catalyst with a calcining agent. After mixing, the calcination treatment is performed to form a calcined waste SCR catalyst, and the vanadium source and the tungsten source are respectively reacted with the calcining agent to form a vanadium salt and a tungsten salt.

In the present invention, a suitable calcination treatment is an alkali calcination method or a sulphation roasting method. Among them, the sulphation roasting method can obtain the same effect as the alkali calcination method, but toxic sulfur oxides are generated during the calcination, so that the alkali roasting method is preferred.

When a sulfation roasting method is employed, the calcining agent is, for example but not limited to, sulfur dioxide or the like. When an alkali baking method is used, the baking agent is, for example but not limited to, sodium carbonate, sodium hydroxide or sodium chloride. In one embodiment of the invention, the calcining agent is sodium carbonate, the vanadium salt formed is NaVO ₃ , and the tungsten salt formed is Na ₂ WO ₄ .

[impregnation step]

In the impregnation step, the calcined waste SCR catalyst is immersed in a liquid capable of dissolving the vanadium salt and the tungsten salt formed by the calcination treatment to dissolve the vanadium salt and the tungsten salt to form an immersion liquid.

The liquid which can dissolve the vanadium salt and the tungsten salt is selected depending on the kind of the vanadium salt and the tungsten salt. In a specific embodiment of the present invention, the vanadium salt is NaVO ₃ , and the tungsten salt is Na ₂ WO ₄ , as long as any solvent capable of dissolving NaVO ₃ and Na ₂ WO ₄ is suitable, and in specific examples, deionization is used. water.

"Steps for removing impurities"

The step of removing impurities is to remove impurities in the immersion liquid to form a purified immersion liquid. Removal of impurities in the immersion liquid prior to the ion exchange step can enhance recovery of vanadium in subsequent ion exchange steps The rate and the recovery of tungsten can increase the purity of the final product (ammonium vanadate and ammonium tungstate in one embodiment of the invention).

The specific manner of the impurity removal step is to select an appropriate mode depending on the type of impurities and the subsequent ion exchange step. Preferably, the step of removing impurities comprises a step of adjusting the pH value, a heating step after the step of adjusting the pH value, and filtering the removed impurity precipitate after the heating step to form the purified immersion liquid.

More specifically, the pH adjustment step is performed by adding an acid agent to the immersion liquid, and adjusting the pH of the immersion liquid to a range of 7.5 to 9.5 to increase impurities such as sodium citrate or sodium hydroxide. The removal rate; adjusting the pH of the immersion liquid to a range of 7.5 to 8.0 is more preferable. The acid agent is, for example but not limited to; (1) monochaotic acid: hydrochloric acid or nitric acid, etc.; (2) bis protonic acid: sulfuric acid, etc.; (3) tribasic acid: phosphoric acid, etc.; wherein the acid agent is double Protonic acid is preferred. In a specific embodiment of the present invention, the immersion liquid further has a small amount of NaAlO ₂ and Na ₂ SiO ₃ , and the acid agent used is sulfuric acid. Therefore, in the pH adjustment step, the addition of sulfuric acid can adjust the immersion liquid. The pH range, NaAlO ₂ and Na ₂ SiO ₃ will be hydrolyzed by sulfuric acid and neutralized to form Al(OH) ₃ , SiO. Precipitation of nH ₂ O and aluminosilicate. In a specific example of the present invention, when the pH of the immersion liquid ranges from 7.5 to 9.5, the immersion liquid contains a vanadium salt ion V ₃ O ₉ ^3- and a tungsten salt ion WO ₄ ^2- .

The heating step is to heat the immersion liquid at a temperature ranging from 30 ° C to 100 ° C after the pH adjustment step, thereby improving the impurity removal rate in the impurity removal step and reducing the loss rate of vanadium and tungsten. This temperature range is preferably from 75 ° C to 90 ° C. In this step, the heating time range is 0.5 Hours to 12 hours; and preferably from 0.5 hours to 2 hours.

Ion Exchange Step

The ion exchange step is to first adjust the pH range of the purified immersion liquid to 1 to 3 to form a liquid to be separated, and then separate the vanadium salt and the tungsten salt in the liquid to be separated by an anion exchange resin, the tungsten salt It will adsorb on the ion exchange resin to obtain a vanadium-containing solution and an anion exchange resin containing tungsten. Wherein, the pH of the liquid to be separated ranges from 1 to 3, and the charge of vanadium and tungsten is different from each other, so that vanadium and tungsten can be separated by an anion exchange resin.

Preferably, the anion exchange resin is selected from the group consisting of a quaternary ammonium salt type, a tertiary ammonium salt type, and a secondary ammonium salt type.

In order to increase the recovery rate of vanadium and the recovery rate of tungsten in the ion exchange step, preferably, the concentration of the vanadium salt in the liquid to be separated ranges from 0.1 to 0.00001 mol/L; preferably, the tungsten salt in the liquid to be separated The concentration ranges from 1 to 0.00001 mol/L. Preferably, the temperature of the liquid to be separated ranges from 21 to 28 °C.

"Vanadium precipitation step"

The vanadium precipitation step is to precipitate a vanadium-containing precipitate from the vanadium-containing solution after the ion exchange step.

In the present invention, the vanadium precipitation step is specifically carried out by first adjusting the pH of the vanadium-containing solution by an alkali agent to a range of 6.5 to 8.5, and then adding a precipitating agent to obtain a vanadium-containing precipitate. The alkali agent is, for example but not limited to, sodium hydroxide, potassium hydroxide, sodium carbonate or potassium carbonate, and sodium hydroxide is preferred. The precipitating agent is, for example but not limited to, ammonium chloride, sulfuric acid Ammonium, ammonium nitrate, ammonium acetate or ammonium carbonate.

"Tungsten precipitation step"

The tungsten precipitation step is such that after the ion exchange step, tungsten ions are desorbed from the tungsten-containing anion exchange resin to form a tungsten-containing solution, and a tungsten-containing precipitate is precipitated from the tungsten-containing solution.

In the present invention, the tungsten precipitation step is specifically performed by first washing the tungsten-containing anion exchange resin with a washing liquid to desorb the tungsten ions adsorbed on the anion exchange resin to obtain a tungsten-containing solution, and then The pH of the tungsten-containing solution was adjusted to 1.5 to 2.5 with an acid agent, and a precipitant was added to obtain an ammonium tungstate precipitate. The washing liquid is, for example but not limited to, ammonia water or sodium hydroxide. The acid agent is, for example but not limited to, hydrochloric acid or nitric acid or the like. The precipitating agent is, for example but not limited to, ammonium chloride, ammonium sulfate, ammonium nitrate or ammonium carbonate.

In the method of the present invention, a waste SCR catalyst including a vanadium source and a tungsten source is first calcined with a suitable calcining agent, followed by impregnation, followed by removing impurities in the impregnation liquid, and adjusting the purified impregnation liquid. After the pH value is within an appropriate range, separation is carried out with an anion exchange resin, and a relatively excellent vanadium recovery rate and tungsten recovery rate can be achieved, and the use of the ion exchange resin does not pollute the environment.

The invention will be further illustrated by the following examples, but It is to be understood that the examples are for illustrative purposes only and are not to be construed as limiting.

<Example>

[Evaluation Evaluation] The following tests were carried out on the following examples and comparative examples:

Impregnation efficiency

Impregnation efficiency (%) = content of vanadium salt (or tungsten salt) in the immersion liquid 钒 content of vanadium source (or tungsten source) in the waste SCR catalyst

The content of the vanadium salt (or tungsten salt) in the immersion liquid is measured by "the method for detecting heavy metals in the commercial waste extract - acid digestion method" (NIEA R306.13C). The content of vanadium source (or tungsten source) in the discarded SCR catalyst is measured by the following method: a waste SCR catalyst and a mixture containing water and concentrated nitric acid (volume ratio of water to concentrated nitric acid = 1:1) The contact was carried out for 30 minutes at a solid-liquid ratio of 1 g/100 ml and a temperature of 95 ° C to obtain a reaction liquid. After the reaction solution is cooled to normal temperature (25 ° C), 3 mL of 30% hydrogen peroxide and 2 mL of water are added, followed by reaction at 95 ° C for 1 hour to obtain a test liquid, and then the "business waste" of the environmental inspection The content of the vanadium source (or tungsten source) in the waste SCR catalyst can be known by measuring the liquid to be tested by the method for detecting heavy metals in the liquid-acid digestion method (NIEA R306.13C).

2. Impurity removal rate

Impurity removal rate (%) = [content of aluminum (or bismuth) in the immersion liquid - content of aluminum (or bismuth) in the purified immersion liquid] content of aluminum (or bismuth) in the immersion liquid

Among them, the inclusion of aluminum (or bismuth) in the immersion liquid and the purified immersion liquid The amount was measured by the "Detection Method for Heavy Metals in Business Waste Extracts - Acid Digestion Method" (NIEA R306.13C) by the Environmental Inspection Institute.

3. Loss rate of vanadium (or tungsten)

Vanadium (or tungsten) loss rate (%) = [vanadium salt (or tungsten salt) content in the impregnation liquid - vanadium salt (or tungsten salt) content in the purified impregnation liquid] vanadium salt in the immersion liquid (or Tungsten salt content

Among them, the content of the vanadium salt (or tungsten salt) in the immersion liquid and the purified immersion liquid is measured by the "heavy metal detection method in the commercial waste extract liquid - acid digestion method" (NIEA R306.13C) by the environmental inspection institute. .

4. Recovery of vanadium (or tungsten)

Vanadium recovery rate (%) = (Vanadium salt content in the liquid to be separated - Vanadium content in the vanadium-containing solution) Vanadium salt content in the liquid to be separated

Tungsten recovery rate (%) = (tungsten salt content in the liquid to be separated - tungsten content in the anion exchange resin containing tungsten) 钨 tungsten salt content in the liquid to be separated

Among them, the vanadium salt (or tungsten salt) in the liquid to be separated, and the vanadium content in the vanadium-containing solution are "the heavy metal detection method in the commercial waste extract-acid digestion method" by the environmental inspection institute (NIEA R306. 13C) measured. The tungsten content in the tungsten-containing anion exchange resin is obtained by subtracting the tungsten content in the vanadium-containing solution from the tungsten salt content in the liquid to be separated.

[Example 1] Pre-Processing Steps

[Roasting step]: Take a waste selective catalytic reduction catalyst (hereinafter referred to as waste SCR catalyst, manufacturer model: SINOx ^@ Argillon Plate type SCR Catalyst), the waste SCR catalyst contains a vanadium source (vanadium oxide V ₂ O ₅ ) and a tungsten source (tungsten oxide WO ₃ ), the waste SCR catalyst is ground to below 140 mesh to form a waste SCR catalyst powder, and a calcining agent (sodium carbonate) is mixed with the waste SCR catalyst powder to form a waste SCR catalyst. a mixture (weight ratio of the waste SCR catalyst powder to sodium carbonate = 10:7), and then the mixture is calcined at 900 ° C for 3 hours to form a calcined waste SCR catalyst, the vanadium source and the tungsten source Reacting with the calcining agent respectively to form a vanadium salt (Na ₂ VO ₃ ) and a tungsten salt (Na ₂ WO ₄ ).

[Immersion step]: the calcined waste SCR catalyst is immersed in deionized water to dissolve the vanadium salt (Na ₂ VO ₃ ) and the tungsten salt (Na ₂ WO ₄ ) under the immersion temperature of 90 ° C, The immersion time was 1 hour and the solid-liquid ratio was 30 g/100 ml to obtain an immersion liquid (pH = 12). The impregnation efficiency is: vanadium 100% and tungsten 95%.

"Steps for removing impurities"

After adjusting the pH of the immersion liquid to 8 with sulfuric acid (concentration: 98%), it was heated to 80 ° C and kept at a constant temperature for 30 minutes, and then filtered to remove an impurity [including: Al(OH) ₃ , SiO. nH ₂ O and aluminosilicate] form a purified impregnation solution (containing vanadium salt V ₃ O ₉ ^3- and tungsten salt WO ₄ ^2- ). In this precipitation separation step, the removal rate of aluminum was 84.27%, the removal rate of ruthenium was 95.97%, the loss rate of vanadium was 5.82%, and the loss rate of tungsten was 6.44%.

Ion Exchange Separation Step

The pH of the purified impregnation solution was adjusted to 1 with hydrochloric acid (concentration: 37%) to form a liquid to be separated (containing vanadium salt VO ²⁺ and tungsten salt W ₁₂ O ₃₉ ^6- ), and an anion exchange resin was added (four The ammonium salt type, manufacturer: Taiyang Chemical, model: DIAION ^® PA316) was added to the liquid to be separated, and the temperature of the liquid to be separated was controlled at 25 ° C, and the total reaction time was set to 8 hours. After 8 hours, a solution containing vanadium (VO ²⁺ ) and an anion exchange resin containing tungsten (W ₁₂ O ₃₉ ^6- ) were obtained. In this ion exchange separation step, the recovery of vanadium was 82%, and the recovery of tungsten was 100%.

"Vanadium precipitation step"

First adjust the pH of the vanadium-containing solution to 8.5 with an aqueous solution of sodium hydroxide (concentration: pH=12), then add a precipitant (ammonium chloride), heat and concentrate for 1 to 2 hours to obtain ammonium vanadate precipitate. Things.

"Tungsten precipitation step"

The tungsten-containing anion exchange resin is washed with a washing liquid (ammonia water, concentration: 7 to 10 mol/L) to desorb the tungsten ions adsorbed on the anion exchange resin, thereby obtaining a tungsten-containing solution, followed by hydrochloric acid (concentration). : 37%) The pH of the tungsten-containing solution was adjusted to 7, and then a precipitant (ammonium chloride) was added, and the mixture was heated and concentrated for 1 to 3 hours to obtain an ammonium tungstate precipitate.

The following Examples 2-1 and 2-2 are further tested for the adjustment of the impurity removal step, and Example 3 is further tested for the adjustment of the ion exchange separation step:

[Example 2-1] Step of removing impurities

After adjusting the pH of the impregnation liquid of Example 1 to 8.5 with hydrochloric acid (concentration: 37%), it was allowed to stand for one day, and filtered to remove a mixture of impurities [including: Al(OH) ₃ , SiO. nH ₂ O and aluminosilicate] form a purified impregnation solution (containing vanadium salt V ₃ O ₉ ^3- and tungsten salt WO ₄ ^2- ). In this precipitation separation step, the removal rate of aluminum was 0.83%, the removal rate of ruthenium was 69.29%, the loss rate of vanadium was 9.72%, and the loss rate of tungsten was 32.90%.

[Example 2-2] Step of removing impurities

After adjusting the pH of the impregnation liquid of Example 1 to 8 with sulfuric acid (concentration: 98%), it was filtered to remove a mixture of impurities [including: Al(OH) ₃ , SiO. nH ₂ O and aluminosilicate] form a purified impregnation solution (containing vanadium salt V ₃ O ₉ ^3- and tungsten salt WO ₄ ^2- ). In this precipitation separation step, the removal rate of aluminum was 47.65%, the removal rate of ruthenium was 21.23%, the loss rate of vanadium was 6.44%, and the loss rate of tungsten was 10.02%.

[Example 3] Ion exchange separation step

The pH of the purified impregnation solution of Example 1 was adjusted to 3 with hydrochloric acid (concentration: 37%) to form a liquid to be separated [containing a small amount of vanadium salt VO ²⁺ , a large amount of vanadium salt V ₁₀ O ₂₆ (OH) ₂ ^4- , and tungsten salt W ₁₂ O ₃₉ ^6- ], add an anion exchange resin (quaternary ammonium salt type, manufacturer: Taiyang Chemical, model: DIAION ^® PA316) to the liquid to be separated, and to be separated The temperature of the liquid was controlled at 25 ° C, and the total reaction time was set to 8 hours. The reaction time is less than 4 hours, and the vanadium salt and the tungsten salt in the liquid to be separated can be effectively separated to obtain a solution containing vanadium [VO ²⁺ , V ₁₀ O ₂₆ (OH) ₂ ^4- ], and a tungsten-containing ( The anion exchange resin of W ₁₂ O ₃₉ ^6- ), at which time the recovery of vanadium is 3% to 12%, and the recovery of tungsten is 100%. However, the reaction time is more than 4 hours, that is, the vanadium salt and the tungsten salt in the liquid to be separated cannot be separated.

The following is a highlight of the efficacy of the method of the present invention, and a comparative example is designed for the pretreatment step, the impurity removal step, and the ion exchange step, respectively.

[Comparative Example 1-1] Pretreatment step

[Immersion step]: taking a waste SCR catalyst containing a vanadium source (vanadium oxide V ₂ O ₅ ) and a tungsten source (tungsten oxide WO ₃ ), grinding the waste SCR catalyst to below 140 mesh to form an abandoned SCR catalyst powder, the waste SCR catalyst powder is immersed in an aqueous sodium hydroxide solution (concentration: 1 M) to dissolve the vanadium source and the tungsten source, and the immersion conditions are: immersion temperature 90 ° C, immersion time 1 hour, and solid-liquid ratio 1 g / 100 ml, an impregnation solution was obtained. The impregnation efficiency is 100% vanadium and 50% tungsten.

[Comparative Example 1-2] Pretreatment step

[baking step]: taking a waste SCR catalyst containing a vanadium source (vanadium oxide V ₂ O ₅ ) and a tungsten source (tungsten oxide WO ₃ ), grinding the waste SCR catalyst to below 140 mesh to form an abandoned The SCR catalyst powder was fired at 700 ° C for 1 hour to form a calcined waste SCR catalyst.

[Immersion step]: the calcined waste SCR catalyst is immersed in deionized water to dissolve the vanadium source and the tungsten source, and the immersion conditions are: immersion temperature 90 ° C, immersion time 1 hour, and solid-liquid ratio 1 g/100 ml, An immersion liquid is obtained. The impregnation efficiency is 62% vanadium and 3% tungsten.

[Comparative Example 1-3] Pretreatment Step

[baking step]: taking a waste SCR catalyst containing a vanadium source (vanadium oxide V ₂ O ₅ ) and a tungsten source (tungsten oxide WO ₃ ), grinding the waste SCR catalyst to below 140 mesh to form an abandoned The SCR catalyst powder was fired at 700 ° C for 1 hour to form a calcined waste SCR catalyst.

[Immersion step]: the calcined waste SCR catalyst is immersed in an aqueous sodium hydroxide solution (concentration: 1 M) to dissolve the vanadium source and the tungsten source, and the immersion conditions are: immersion temperature 90 ° C, immersion time 1 hour and Solid solution An immersion liquid was obtained in an amount of 1 g/100 ml. The impregnation efficiency is: vanadium 87% and tungsten 30%.

[Comparative Example 2] Ion exchange separation step

The pH of the purified impregnation solution of Example 1 was adjusted to 7 with hydrochloric acid (concentration: 37%) to form a liquid to be separated [containing vanadium salt V ₃ O ₉ ^3- , and tungsten salt HWO ₄ ^2- ], added An anion exchange resin (quaternary ammonium salt type, manufacturer: Taiyang Chemical, model: DIAION ^® PA316) was added to the liquid to be separated, and the temperature of the liquid to be separated was controlled at 25 ° C for a total reaction time of 8 hours. After 8 hours, the ion exchange separation step of Comparative Example 3 could not separate the vanadium salt and the tungsten salt in the liquid to be separated.

[Result analysis]

Table 1 shows the finishing of Example 1 and Comparative Examples 1-1 to 1-3, and it is known from Comparative Examples 1-1 to 1-3 that when baking is not carried out (Comparative Example 1-1), When the calcination is carried out but the calcining agents (1-2 and 1-3) are not used, the impregnation efficiency of vanadium and tungsten cannot be simultaneously increased. In the first embodiment, the method of pre-baking and re-impregnation, together with a suitable calcining agent, can obtain relatively excellent vanadium impregnation efficiency (100%) and tungsten impregnation efficiency (95%).

Table 2 shows the finishing of Examples 1, 2-1 and 2-2. In the comparison of Examples 2-1 and 2-2, the manner of the impurity removing step of Example 1 after heating the immersion liquid after adjusting the pH value can be found. It has a better performance in terms of impurity removal rate, vanadium and tungsten loss rate.

Table 3 shows the finishing of Examples 1, 3 and Comparative Example 2. In Comparative Example 2, the pH of the liquid to be separated is 7, so that the vanadium salt and the tungsten salt in the liquid to be separated are adsorbed on the anion exchange resin. The purpose of separating and recovering vanadium and tungsten in the waste SCR catalyst cannot be achieved. And in the control of Example 3, it can be seen that the pH of the liquid to be separated can successfully achieve the purpose of separating and recovering vanadium and tungsten in the waste SCR catalyst at a pH of 1 to 3, but if the pH of the liquid to be separated is When it is 3 hours, the vanadium salt and the tungsten salt are adsorbed on the anion exchange resin. Therefore, if the convenience of handling is considered, it is preferable to control the pH of the liquid to be separated to be less than 3.

In summary, the method for recovering vanadium and tungsten from the waste selective catalytic reduction catalyst of the present invention, by sequentially performing the calcination step, the impregnation step, the impurity removal step and the ion exchange step, can be complemented by the steps Successfully separated and recovered vanadium and tungsten from waste SCR catalyst, and achieved quite excellent vanadium recovery rate and tungsten recovery rate. At the same time, the method of the present invention adopts the ion exchange step, so that it does not cause environmental pollution, so it can indeed The object of the invention is achieved.

However, the above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent change of the patent application scope and the patent specification content of the present invention is Modifications are still within the scope of the invention.

Claims (10)

A method for recovering vanadium and tungsten from a waste selective catalytic reduction catalyst, comprising: providing a waste selective catalytic reduction catalyst comprising a vanadium source and a tungsten source; a pretreatment step comprising a calcination step and an impregnation Step: the calcination step is: mixing the waste selective catalytic reduction catalyst with a calcining agent and performing calcination treatment to form a calcined waste selective catalytic reduction catalyst, wherein the vanadium source and the tungsten source are respectively The calcining agent is reacted to form a vanadium salt and a tungsten salt, and the impregnating step is: immersing the calcined waste selective catalytic reduction catalyst in a vanadium salt and a tungsten salt which can be formed by dissolving the roasting treatment a liquid to dissolve the vanadium salt and the tungsten salt to form an immersion liquid; an impurity removal step to remove impurities in the immersion liquid to form a purified immersion liquid; and an ion exchange step to impregnate the purification The pH range of the liquid is adjusted to 1 to 3 to form a liquid to be separated, and the vanadium salt and the tungsten salt in the liquid to be separated are separated by an anion exchange resin to obtain a vanadium-containing solution and a tungsten-containing solution. Anion exchange resin. The method of claim 1, wherein when the pH of the liquid to be separated ranges from 3, the anion exchange resin is contacted with the liquid to be separated for no more than 4 hours. The method of claim 1, wherein the pH value of the liquid to be separated is The circumference is less than 3. The method of claim 1, wherein the calcination treatment is a base roasting method. The method of claim 4, wherein the calcining agent is selected from the group consisting of sodium carbonate, sodium hydroxide or sodium chloride. The method of claim 1, wherein the step of removing impurities comprises a step of adjusting the pH to adjust the pH range of the immersion liquid to 7.5 to 9.5. The method of claim 6, wherein the step of removing impurities further comprises a heating step of heating the immersion liquid at a temperature ranging from 30 ° C to 100 ° C after the step of adjusting the pH. The method of claim 1, wherein the anion exchange resin is selected from the group consisting of a quaternary ammonium salt type, a tertiary ammonium salt type, and a secondary ammonium salt type. The method of claim 1, further comprising a vanadium precipitation step of depositing a vanadium-containing precipitate from the vanadium-containing solution after the ion exchange step. The method of claim 1, further comprising a tungsten precipitation step of desorbing tungsten ions from the tungsten-containing anion exchange resin and forming a tungsten-containing solution after the ion exchange step, and from the tungsten-containing solution A precipitate containing tungsten is precipitated in the solution.