CN113564386A

CN113564386A - Method for recovering molybdenum from waste nickel-molybdenum catalyst

Info

Publication number: CN113564386A
Application number: CN202110837756.1A
Authority: CN
Inventors: 张广积; 李望良; 李媛媛; 杨超
Original assignee: Nanjing Jiuzhang Chemical Tech Co Ltd; Institute of Process Engineering of CAS; University of Chinese Academy of Sciences
Current assignee: Nanjing Jiuzhang Chemical Tech Co Ltd; Institute of Process Engineering of CAS; University of Chinese Academy of Sciences
Priority date: 2021-07-23
Filing date: 2021-07-23
Publication date: 2021-10-29
Anticipated expiration: 2041-07-23
Also published as: CN113564386B

Abstract

The invention provides a method for recovering molybdenum from a waste nickel-molybdenum catalyst, which comprises the following steps: (1) mixing hydrogen peroxide and a waste nickel-molybdenum catalyst, and then carrying out one-step reaction to obtain a leaching solution; (2) and (2) adding ammonia water into the leachate obtained in the step (1), carrying out two-step reaction, adding ammonia water, carrying out three-step reaction, and filtering to obtain a molybdenum-containing filtrate. The method has the advantages of low temperature, no need of a pressurized reactor, simple operation and low equipment investment. The resulting ammonium molybdate solution may be recovered using conventional methods.

Description

Method for recovering molybdenum from waste nickel-molybdenum catalyst

Technical Field

The invention belongs to the technical field of resource recovery, and relates to a method for recovering molybdenum from a waste nickel-molybdenum catalyst.

Background

At present, 20 million tons of oil refining waste catalysts are generated in the oil refining industry of China every year, only about 10 percent of the waste catalysts are treated in a resource mode, and most of the waste catalysts can only be stockpiled. The waste catalyst belongs to dangerous waste, contains a large amount of harmful substances, and has high environmental risk in long-term storage. The nickel-molybdenum catalyst is a hydrogenation catalyst commonly used in the oil refining process, usually gamma-alumina is used as a carrier, the molybdenum content can reach more than 10%, the nickel content is between 3 and 10%, the nickel is mainly present in a sulfide form, and the rest elements are mainly a small amount of iron and silicon. The catalyst can be used for extracting valuable metals such as molybdenum and the like after being scrapped, and can be used as secondary resources for utilization, wherein the element with the most recovery value is molybdenum. Because molybdenum mainly exists in a sulfide form, oxidation conversion is needed before extraction, and a commonly used oxidation method is high-temperature roasting, and a certain amount of alkaline substances such as sodium carbonate and the like are added to inhibit the release of sulfur dioxide and improve the leaching rate of molybdenum. Although the method is simple to operate, high-temperature roasting is needed, smoke pollution is easily caused, and the difficulty of post-treatment is increased due to the addition of excessive sodium carbonate. It has also been reported that the amount of sulfuric acid consumed is large and the resulting aluminum sulfate solution is difficult to recycle because the catalyst support alumina is dissolved in sulfuric acid and then the nickel sulfide and molybdenum sulfide in the residue are recovered.

The molybdenum content in the waste nickel-molybdenum catalyst is very high, and the waste nickel-molybdenum catalyst exists in a sulfide situation, so that the waste nickel-molybdenum catalyst can be leached to a certain extent according to the treatment mode of molybdenum sulfide ore. However, the molybdenum leaching agent has complex components, and other elements are easy to leach simultaneously in the molybdenum leaching process, so that the leachate is difficult to treat. For example, in the treatment process of molybdenum sulfide ore, molybdenum sulfide is converted into molybdic acid and then extracted by adopting a concentrated nitric acid oxidation pressure cooking mode; or by using oxygen gas pressure leaching with the addition of sodium hydroxide. The reaction conditions of the method are harsh, and the strong acid or strong alkali condition can cause alumina in the waste catalyst to be dissolved, so that the method cannot be directly used for extracting molybdenum in the waste catalyst. On the other hand, the molybdenum sulfide in the waste catalyst is formed by vulcanizing molybdate, the crystallinity is poorer than that of molybdenum sulfide ore, and the molybdenum in the molybdenum sulfide ore is easier to be oxidized and dissolved and can be leached under a milder condition. Therefore, in order to selectively leach molybdenum from the waste nickel-molybdenum hydrogenation catalyst, a method for oxidizing and leaching molybdenum under mild conditions needs to be developed.

CN111573733A discloses a method for preparing a hydrogenation catalyst by using a molybdenum-nickel spent catalyst. Mixing, roasting and leaching pretreated molybdenum-nickel system waste catalyst powder and alkali to obtain a molybdate solution and alumina filter residue, and adjusting the pH of the molybdate solution to remove aluminum ions to obtain molybdic acid; mixing the alumina filter residue with alkali, and then carrying out secondary roasting and leaching to obtain a sodium aluminate solution and a nickel oxide solid; cooling and crystallizing the sodium aluminate solution, and filtering and separating to obtain hydrated sodium aluminate solid and dilute sodium aluminate solution; drying the hydrated sodium aluminate solid to obtain sodium aluminate; introducing carbon dioxide into the dilute sodium aluminate solution, and obtaining a primary product after the reaction is finished; and performing secondary parallel flow reaction on the primary product and acid liquor, and finally aging, filtering and drying to obtain the pseudo-boehmite. The method only adjusts the pH value to generate molybdic acid to recover molybdenum, and the strong acid or strong alkali condition can cause alumina in the waste catalyst to be dissolved, so that the impurity content in the recovered molybdenum is higher.

CN101435027B discloses a method for recovering molybdenum from molybdenum-containing spent catalyst, which mainly comprises the following steps: the method comprises the steps of pretreating the molybdenum-containing spent catalyst, leaching molybdenum into a solution, purifying and recovering molybdenum from the solution, wherein the pretreatment of the molybdenum-containing spent catalyst is to fully mix the crushed spent catalyst with an alkaline substance and magnesium oxide in a proper proportion and then carry out high-temperature roasting treatment. The method needs high-temperature roasting, smoke pollution is easy to cause, and the difficulty of post-treatment is increased due to the addition of excessive alkaline substances.

The scheme has the problems that the recovered molybdenum contains more impurities and is easy to cause pollution or difficult in post-treatment, so that the development of a method for recovering molybdenum from the waste catalyst, which has high molybdenum recovery purity, is environment-friendly and simple in post-treatment, is necessary.

Disclosure of Invention

The invention aims to provide a method for recovering molybdenum from a waste nickel-molybdenum catalyst, which adopts hydrogen peroxide and ammonia water to leach molybdenum in the waste nickel-molybdenum catalyst, and the reaction is carried out under the condition of neutral to alkalescence, thereby avoiding the simultaneous dissolution of other components such as alumina and the like and realizing selective leaching; the reaction temperature is lower, a pressurized reactor is not needed, the operation is simple, and the equipment investment is low. The resulting ammonium molybdate solution may be recovered using conventional methods.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for recovering molybdenum from a waste nickel-molybdenum catalyst, which comprises the following steps:

(1) mixing hydrogen peroxide and a waste nickel-molybdenum catalyst, and then carrying out one-step reaction to obtain a leaching solution;

(2) and (2) adding ammonia water into the leachate obtained in the step (1), carrying out two-step reaction, adding ammonia water, carrying out three-step reaction, and filtering to obtain a molybdenum-containing filtrate.

The invention adopts hydrogen peroxide as an oxidant to carry out oxidation leaching on the waste nickel-molybdenum catalyst, and adds a proper amount of ammonia water to neutralize sulfuric acid generated in the oxidation process, so that the reaction is basically carried out under a neutral condition. In order to improve the leaching rate of molybdenum, ammonia water is gradually added in the later stage of the reaction to promote further dissolution of molybdenum. The leached molybdenum enters the solution in the form of ammonium molybdate and can be recovered by conventional precipitation of ammonium polymolybdate.

Preferably, the mass concentration of the hydrogen peroxide in the step (1) is 10-20%, for example: 10%, 12%, 15%, 18%, 20%, etc.

Preferably, the temperature of the one-step reaction in the step (1) is 40-90 ℃, for example: 40 ℃, 60 ℃, 70 ℃, 80 ℃ or 90 ℃ and the like.

Preferably, the time of the one-step reaction is 20-40 min, for example: 20min, 25min, 30min, 35min or 40min and the like.

Preferably, stirring is performed during the one-step reaction.

Preferably, the stirring speed is 200-300 rpm, such as: 200rpm, 220rpm, 250rpm, 280rpm, 300rpm, or the like.

Preferably, the mass concentration of the ammonia water in the step (2) is 10-30%, for example: 10%, 15%, 20%, 25%, 30%, etc.

Preferably, the pH of the two-step reaction is 7-8, such as: 7. 7.2, 7.5, 7.8 or 8, etc.

Preferably, the temperature of the two-step reaction in the step (2) is 50-80 ℃, for example: 50 ℃, 60 ℃, 70 ℃ or 80 ℃ and the like.

Preferably, the time of the two-step reaction is 30-60 min, for example: 30min, 35min, 40min, 45min, 50min or 60min and the like.

Preferably, the temperature of the three-step reaction in the step (2) is 40-90 ℃, for example: 40 ℃, 60 ℃, 70 ℃, 80 ℃ or 90 ℃ and the like.

Preferably, the time of the three-step reaction is 30-60 min, for example: 30min, 35min, 40min, 45min, 50min or 60min and the like.

Preferably, the pH of the three-step reaction in the step (2) is 9-10, such as: 9. 9.2, 9.5, 9.8 or 10, etc.

And (3) acidifying and precipitating the molybdenum-containing filtrate obtained in the step (2).

Preferably, the acid solution of the acidified precipitate comprises any one of sulfuric acid, nitric acid or hydrochloric acid.

As a preferred embodiment of the present invention, the method comprises the steps of:

(1) mixing hydrogen peroxide with the concentration of 10-20% and a waste nickel-molybdenum catalyst, and reacting at 40-90 ℃ for 20-40 min to obtain a leaching solution;

(2) adding ammonia water into the leachate obtained in the step (1) to adjust the pH value to 7-8, reacting at 40-90 ℃ for 30-60 min, adding ammonia water to adjust the pH value to 9-10, reacting for 30-60 min, and filtering to obtain a filtrate;

(3) and (3) acidifying and precipitating the filtrate obtained in the step (2) to obtain ammonium polymolybdate.

Compared with the prior art, the invention has the following beneficial effects:

(1) the invention adopts the hydrogen peroxide and the ammonia water to leach the molybdenum in the waste nickel-molybdenum catalyst, the reaction is carried out under the condition of neutral to alkalescence, the aluminum oxide and other components can be prevented from being dissolved at the same time, and the selective leaching is realized.

(2) The method has the advantages of low reaction temperature, no need of a pressurized reactor, simple operation and low equipment investment. The resulting ammonium molybdate solution may be recovered using conventional methods.

Drawings

FIG. 1 is a schematic flow chart of the method for recovering molybdenum from waste nickel-molybdenum catalyst in example 1 of the invention.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

The waste nickel-molybdenum catalyst selected in this example is a waste catalyst containing 12.5% by mass of molybdenum, 2.4% by mass of nickel, 25.4% by mass of aluminum, and 9.4% by mass of sulfur, wherein molybdenum mainly exists in the form of molybdenum sulfide, but the crystallinity is poor, and aluminum basically exists in the form of amorphous alumina.

The embodiment provides a method for recovering molybdenum from waste nickel-molybdenum catalyst, which comprises the following steps:

(1) using 30% hydrogen peroxide by mass concentration, adding 40mL of hydrogen peroxide into a 500mL three-neck flask, diluting to 100mL with deionized water, adding 20g of waste nickel-molybdenum catalyst, and stirring for reaction at 60 ℃ at the stirring speed of 250 rpm. Leaching solution is obtained in 30 min;

(2) slowly adding ammonia water with the mass concentration of 20% into the leaching solution obtained in the step (1), keeping the pH value at 7.5, reacting for 45min, and then adding ammonia water again until the pH value is 9.5. After reacting for 1h, stopping heating, filtering to obtain filtrate and filter residue, wherein the mass content of aluminum in the leached residue is 39.7%, the mass content of molybdenum is 0.2%, the mass content of sulfur is reduced to 0.5%, and the mass content of molybdenum in the filtrate is 18.5 g/L;

(3) and (3) adding sulfuric acid with the mass concentration of 8% into the filtrate obtained in the step (2), and precipitating to obtain ammonium polymolybdate.

The process flow diagram of the method of this example is shown in fig. 1.

Example 2

The waste nickel-molybdenum catalyst selected in the embodiment is milled to below 200 meshes after being washed by acetone and deoiled. The mass content of molybdenum, nickel, sulfur and aluminum was 11.8%, 3.5%, 10.4% and 26.7%, respectively.

(1) 20g of the ground spent catalyst was slurried with 60mL of deionized water and added to a three-neck flask. Adding 40mL of hydrogen peroxide with the mass concentration of 30%, and reacting at 60 ℃ for 30min to obtain a leaching solution;

(2) and (2) slowly adding ammonia water with the mass concentration of 20% into the leachate obtained in the step (1), keeping the pH value at 7.5, reacting for 2 hours, filtering, adding 30mL of ammonia water with the mass concentration of 20% into filter residues, and stirring and leaching for 30min again. Filtering, combining the two filtrates, wherein the mass content of molybdenum in the filter residue is 0.1%, the mass content of nickel is 3.1%, the mass content of aluminum is 40.2%, the mass content of sulfur is reduced to 0.8%, and the mass content of molybdenum in the filtrate is 21.6 g/L;

Example 3

The present example is different from example 1 only in that the amount of hydrogen peroxide added in step (1) is 30mL, (the concentration of hydrogen peroxide after dilution is 9%), and other conditions and parameters are completely the same as those in example 1.

Example 4

The present embodiment is different from embodiment 1 only in that the hydrogen peroxide solution in step (1) is diluted from 30% to 20%, and other conditions and parameters are completely the same as those in embodiment 1.

Example 5

This example differs from example 1 only in that the pH of the reaction after the first addition of aqueous ammonia in step (2) is 7, and the other conditions and parameters are exactly the same as those in example 1.

Example 6

This example differs from example 1 only in that the reaction pH after the first addition of ammonia in step (2) is 8, and the other conditions and parameters are exactly the same as those in example 1.

Example 7

This example differs from example 1 only in that the pH of the reaction after the second addition of ammonia in step (2) is 9, and the other conditions and parameters are exactly the same as those in example 1.

Example 8

This example is different from example 1 only in that the pH of the reaction after the second addition of ammonia in step (2) is 10, and the other conditions and parameters are exactly the same as those in example 1.

Comparative example 1

The comparative example differs from example 1 only in that no second ammonia is added and the other conditions and parameters are exactly the same as in example 1.

Comparative example 2

The comparative example is different from example 2 only in that hydrogen peroxide is changed into 68% concentrated nitric acid, and 20mL of the concentrated nitric acid is diluted to 100 mL. After one-step leaching, ammonia water is not added for neutralization, and other conditions and parameters are completely the same as those of example 2.

The filtrates and filter residues obtained in step (2) of examples 1 to 8 and comparative examples 1 to 2 were taken to test the contents of internal elements, and the test results are shown in table 1:

TABLE 1

As can be seen from Table 1, in the filter residue obtained by the method of the present invention, the molybdenum content is less than 3.5 wt%, and the concentration of molybdenum in the filtrate is more than 14.3g/L, as can be seen from examples 1-8.

Compared with the embodiment 1 and the embodiment 3-4, the concentration of hydrogen peroxide can influence the amount of molybdenum recovered by the method, the concentration of hydrogen peroxide is controlled to be 1-20%, molybdenum in the waste nickel-molybdenum catalyst can be leached to the maximum extent, if the concentration of hydrogen peroxide is too low, the reaction is slow, the reaction time is too long, the molybdenum leaching rate is low, if the concentration of hydrogen peroxide is too high, the initial reaction is violent, the hydrogen peroxide is decomposed too fast to generate oxygen, so that the consumption of hydrogen peroxide is caused, and meanwhile, the temperature rises rapidly to generate a large amount of bubbles, so that the overflow of reactants is easily caused.

Comparing the embodiment 1 with the embodiments 5 to 8, the pH value of the reaction after the ammonia water is added in the first step and the ammonia water is added in the second step can influence the recovery amount of molybdenum, the ammonia water is added in the first step for neutralizing sulfuric acid generated by the reaction of hydrogen peroxide and molybdenum sulfide, the solubility of the generated molybdic acid is low, and the leaching rate can be improved by adding the ammonia water in the second step to form ammonium molybdate with molybdic acid, so that the pH value is further increased in the later stage of the reaction, the ammonium molybdate is continuously obtained by the reaction, the generated ammonium molybdate solution can generate ammonium molybdate crystals after being acidified, and the leaching effect is not obviously improved when the pH value reaches 10, namely, the pH value after the ammonia water is added in the second step reaches 10, the molybdenum can be completely leached, but the excessive alkali concentration can influence the subsequent acidification precipitation, so that excessive acid is used for acidification, and waste is caused.

Compared with the comparative example 1, the method has the advantages that the solubility of molybdenum in the solution can be improved by adding ammonia water to generate ammonium molybdate after the molybdic acid is generated, and then the molybdenum is extracted to the maximum extent.

Compared with the embodiment 2, the method disclosed by the invention has the advantages that the hydrogen peroxide is used as the oxidant to leach the molybdenum in the waste nickel-molybdenum catalyst, the molybdenum can be selectively leached under mild conditions, the hydrogen peroxide is neutral, and the aluminum oxide in the catalyst can be prevented from being dissolved out, in the comparative example 2, nitric oxide is released in the leaching process due to the fact that nitric acid is used as the oxidant, the leaching amount of aluminum is large due to acidic condition leaching, the leaching solution contains a large amount of aluminum ions, aluminum hydroxide colloid is formed on time when the molybdic acid is acidified and precipitated, and the subsequent filtration and separation cannot be carried out.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.

Claims

1. A method for recovering molybdenum from a spent nickel molybdenum catalyst, the method comprising the steps of:

2. The method according to claim 1, wherein the mass concentration of the hydrogen peroxide in the step (1) is 10-20%.

3. The method of claim 1 or 2, wherein the temperature of the one-step reaction in the step (1) is 40-90 ℃;

preferably, the time of the one-step reaction is 20-40 min.

4. The method of any one of claims 1 to 3, wherein stirring is performed during the one-step reaction;

preferably, the stirring speed is 200-300 rpm.

5. The method according to any one of claims 1 to 4, wherein the mass concentration of the ammonia water in the step (2) is 10 to 30%;

preferably, the pH value of the two-step reaction is 7-8.

6. The method according to any one of claims 1 to 5, wherein the temperature of the two-step reaction in the step (2) is 40 to 90 ℃;

preferably, the time of the two-step reaction is 30-60 min.

7. The method according to any one of claims 1 to 6, wherein the temperature of the three-step reaction in step (2) is 40 to 90 ℃;

preferably, the time of the three-step reaction is 30-60 min.

8. The method according to any one of claims 1 to 7, wherein the pH of the three-step reaction in step (2) is 9 to 10.

9. The method according to any one of claims 1 to 8, wherein the molybdenum-containing filtrate obtained in step (2) is subjected to an acidification precipitation;

10. The method according to any one of claims 1 to 9, characterized in that it comprises the steps of: