A method for recovering molybdenum from waste nickel and aluminum powder for catalyst

Abstract

The present invention relates to the technical field of solid waste resource recycling and utilization, and specifically discloses a method for recovering molybdenum from waste nickel-aluminum powder for catalysts. The method provided by the present invention for recovering molybdenum from waste nickel-aluminum powder for catalysts comprises the steps of: mixing the waste nickel-aluminum powder with a flux to form balls, followed by roasting in a microwave environment to obtain roasted slag; the roasted slag is pre-activated by ultrasonic wave, followed by water leaching, and then solid-liquid separation to obtain a molybdenum-containing leachate and nickel-aluminum leach slag, respectively. The method of the present invention can achieve efficient leaching of molybdenum from waste nickel-aluminum powder for catalysts, and the obtained leaching slag can be directly used as a raw material for catalyst preparation after simple treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource recycling, and in particular to a method for recovering molybdenum from waste nickel-aluminum powder used as a catalyst. Background Art

[0002] Molybdenum is a strategically important rare metal with a wide range of applications. In the chemical industry, it is used to manufacture corrosion-resistant equipment and containers. It is also an excellent conductor of electricity, used in electrodes, capacitors, and other materials. Furthermore, its high strength and hardness, along with its excellent mechanical properties, make it crucial for applications in high-strength alloys, electronic devices, and aerospace. With the rapid development of modern industry, the demand for molybdenum raw materials has increased annually. Extracting molybdenum from ores alone is no longer sufficient to meet the demands of production growth, making the recycling and reuse of molybdenum-containing secondary resources of great strategic importance.

[0003] Raney nickel catalyst is a solid-state heterogeneous catalyst composed of fine, porous nickel-aluminum alloy grains. It is produced by activating nickel-aluminum alloy powder and is primarily used in catalytic hydrogenation reactions. After repeated use, the catalytic activity of Raney nickel catalyst decreases, and deactivation produces a large amount of waste nickel-aluminum powder. This waste nickel-aluminum powder is an important secondary resource, containing not only nickel and aluminum but also rare metals such as vanadium and molybdenum.

[0004] Currently, when processing this type of scrap nickel and aluminum powder, the vanadium and molybdenum metals are generally recovered. The conventional recovery method involves sodium-based roasting of the scrap nickel and aluminum powder, followed by water leaching to produce a vanadium- and molybdenum-containing leachate. However, it has been found that after conventional methods have recovered vanadium and molybdenum, the scrap nickel and aluminum powder still contains molybdenum metal, even exceeding the molybdenum content found in some molybdenum-containing lean ores, making it a critical secondary resource with significant economic value. However, due to the complex composition of scrap nickel and aluminum powder and the difficulty of processing it, there is still no effective method for recovering molybdenum.

[0005] Therefore, under the current severe reality of decreasing mineral resources and worsening ecological environment damage, conducting research on the comprehensive recovery and utilization of molybdenum in waste nickel and aluminum powder has both environmental and economic benefits. Summary of the Invention

[0006] The main technical problem solved by the present invention is to provide a method for recovering molybdenum from waste nickel-aluminum powder for catalysts, which can achieve effective leaching of molybdenum from waste nickel-aluminum powder for catalysts.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for recovering molybdenum from waste nickel and aluminum powder for catalyst, comprising the steps of:

[0008] S1: Mixing waste nickel and aluminum powder with flux to form balls, and then calcining them in a microwave environment to obtain loose and porous slag;

[0009] The calcination conditions for calcination in a microwave environment are as follows: microwave power of 400-800W, calcination temperature of 400-600°C;

[0010] S2: The roasted slag is pre-activated by ultrasonic wave, then treated with water, and then solid-liquid separation is carried out to obtain molybdenum-containing leaching solution and nickel-aluminum leaching slag respectively.

[0011] As an embodiment of the present invention, the waste nickel and aluminum powder, flux and water are mixed to form balls, and the ball diameter is controlled to be 1 to 3 cm.

[0012] As an embodiment of the present invention, the flux is sodium hydroxide and / or potassium hydroxide.

[0013] As an embodiment of the present invention, the molar number of the flux is 1.2 to 2.0 times the molar number of molybdenum ions contained in the scrap nickel-aluminum powder.

[0014] Preferably, the molar number of the flux is 1.5 to 1.8 times the molar number of molybdenum ions contained in the scrap nickel-aluminum powder.

[0015] As an embodiment of the present invention, the calcination time in step S1 is controlled to be 20 to 30 minutes.

[0016] In one embodiment of the present invention, the ultrasonic pre-activation comprises: treating the calcined slag with ultrasound at room temperature, with an ultrasonic power of 200-400W and a treatment time of 3-5 minutes. Room temperature refers to a temperature range of 20-40°C, preferably a temperature range of 25-35°C.

[0017] In one embodiment of the present invention, water is added to the calcined slag before ultrasonic treatment to form a hydrated calcined slag material having a liquid-to-solid ratio of 2.5 to 5.0 mL / g. Ultrasonic pre-activation treatment involves treating the calcined slag material with ultrasonic waves at room temperature. The liquid-to-solid ratio refers to the ratio of the liquid volume (mL) of the calcined slag material to the mass (g) of the material contained therein.

[0018] As an embodiment of the present invention, the water immersion treatment includes: heating the water-containing roasted slag material after ultrasonic pre-activation to 75-90° C. and stirring for 30-60 minutes.

[0019] The molybdenum-containing leachate obtained by the present invention contains metallic molybdenum at a mass percentage of ≥98% based on the total mass of the metals contained (excluding sodium or potassium). The leachate has high purity, significantly simplifies the subsequent purification process for molybdenum, and metallic molybdenum can be obtained through simple treatment.

[0020] The nickel-aluminum leaching residue obtained by the present invention has a nickel-aluminum mass percentage content of ≥98% based on the total mass of the metals contained. The nickel-aluminum leaching residue has high purity and can be directly used as a raw material for preparing a Raney nickel catalyst after simple treatment.

[0021] The present invention provides a method for recovering molybdenum from waste nickel-aluminum powder for catalysts. The raw material to be processed is waste nickel-aluminum powder from which vanadium and molybdenum have been recovered by conventional methods, and most of the vanadium and soluble molybdenum have been removed. The molybdenum element in this waste nickel-aluminum powder mainly exists in the form of insoluble phases such as NiMoO4, and it is difficult to effectively recover it using conventional processes. The method of the present invention first mixes the waste nickel-aluminum powder with a flux to form balls, and then performs low-temperature roasting in a microwave environment to obtain loose and porous roasting slag; the roasting slag is then treated with an ultrasonic pre-activation-water leaching process, and after solid-liquid separation, a leachate containing metallic molybdenum and nickel-aluminum leaching slag can be obtained. The method of the present invention can achieve effective leaching of molybdenum from insoluble NiMoO4 in waste nickel-aluminum powder for catalysts, greatly improving the leaching efficiency of molybdenum in waste nickel-aluminum powder, and the leached slag can be directly used as a raw material for catalyst preparation after simple treatment.

[0022] The molybdenum in the raw materials processed by the present invention primarily exists in the form of insoluble phases such as NiMoO4. Effective dissolution of molybdenum from insoluble phases is a common challenge because these phases can only be effectively dissolved after their chemical bonds are broken. This often requires temperatures exceeding 1,000 degrees Celsius, or even higher temperatures and extended periods of time, increasing production costs, energy consumption, and placing higher demands on equipment.

[0023] The inventors have found that the chemical bonds of insoluble molybdenum-containing phases such as NiMoO4 in scrap nickel and aluminum powder are stable and difficult to decompose under low temperature conditions. Their chemical bonds can only be destroyed under high temperature conditions or special field conditions. The present invention adopts a microwave low-temperature roasting treatment method, utilizing the special effect of microwaves on the Ni-Mo-O chemical bond and the rapid selective heating characteristics of the flux under the microwave field. Under low temperature conditions below 600 degrees, the Ni-Mo-O chemical bond is destroyed, and Mo is converted into a water-soluble phase. Macroscopically, the flux is added with water to form a viscous slurry, which is then mixed with the scrap nickel and aluminum powder to form balls, so that the raw materials and flux are evenly distributed in the spheres. In the microwave field, the water is first rapidly heated and dried, and the pellets form a loose and porous structure. With the subsequent rapid heating of the flux, the loose and porous structure becomes more obvious, providing conditions and channels for in-depth destruction by microwaves. At the microscopic level, the Ni-Mo-O chemical bond is destroyed, and at the same time, the flux rapidly melts under the microwave field, forming a synergistic effect, which causes the molybdenum-containing phase to transform from insoluble to soluble, which is beneficial to the smooth progress of the subsequent leaching reaction.

[0024] The study also found that low-temperature calcination can prevent the reaction of molybdenum-containing compounds with nickel to form new insoluble phases such as Ni-Mo-O. Therefore, controlling the calcination temperature is crucial, neither too high nor too low. Only by controlling microwave calcination within the appropriate calcination temperature range can the effective dissolution of molybdenum from insoluble phases such as NiMoO4 be achieved.

[0025] The roasted slag obtained by microwave roasting is spherical (spherical diameter 1 to 3 cm). If it is directly treated by traditional stirring method, the leaching rate will inevitably decrease due to the uneven dispersion of the material. If the leaching rate needs to be improved, the roasted slag can be ground and then leached, but this increases energy consumption. The present invention proposes to use ultrasonic pre-activation-water leaching process to treat the roasted slag, abandoning the process of grinding the roasted slag, which significantly reduces the process energy consumption. First, the roasted slag (spherical) is added with water and then pre-activated by normal temperature ultrasound. This step can break up the pelletized roasted slag macroscopically, so that the leaching process material is evenly dispersed in the leaching agent water. Microscopically, due to the cavitation effect of the ultrasound, the surface particles of the roasted slag can be activated, which promotes the leaching reaction and greatly shortens the time of the water leaching process. The leachate obtained by the treatment of the present invention has a high molybdenum content and an extremely low nickel and aluminum content; the nickel and aluminum are mainly present in the leaching residue, and the nickel and aluminum content in the leaching residue is greater than 98% by mass, with high purity. The leaching residue can be directly used as a raw material for catalyst preparation after simple treatment.

[0026] The method for recovering molybdenum from waste nickel-aluminum powder provided by the present invention is designed to address the unique, insoluble composition and structure of molybdenum in the raw material. Experimental results show that the method can leach most of the molybdenum from the waste nickel-aluminum powder, with a molybdenum recovery rate exceeding 97%. Simultaneously, the nickel-aluminum leaching rate is less than 0.3%, resulting in a high-purity leachate, significantly simplifying the subsequent molybdenum purification process. The leached residue after leaching has a nickel-aluminum content (calculated by total metal mass) of greater than 98%, exhibiting high purity. The residue can be directly used as a catalyst preparation raw material after simple processing.

[0027] The method for recovering molybdenum from waste nickel-aluminum powder for catalysts provided by the present invention realizes the rapid and effective recovery of molybdenum from the waste nickel-aluminum powder. In addition, the recovery and treatment method has low production cost, low labor intensity, and short treatment time, thereby increasing the treatment capacity of the waste nickel-aluminum powder, being more conducive to promoting the resource treatment of the waste nickel-aluminum powder, and realizing energy conservation, emission reduction, and green production in the molybdenum industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a scanning electron microscope image of the insoluble NiMoO4 phase in the waste nickel and aluminum powder treated in Example 1 of the present invention;

[0029] Figure 2 This is a picture of the loose and porous calcined slag obtained by processing in step S1 in Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The following examples are intended to further illustrate the present invention, but are not intended to limit the scope of protection of the present invention.

[0031] In the following examples, the pharmaceutical agents used are all commercially available products. Unless otherwise specified, the percentages in each example are by mass.

[0032] Example 1

[0033] This embodiment provides a method for recovering molybdenum from waste nickel-aluminum powder used as a catalyst. The raw material waste nickel-aluminum powder to be processed is waste nickel-aluminum powder provided by a chemical enterprise in Liaoning Province, which has been subjected to conventional methods to recover vanadium and molybdenum. The powder is in the form of light green powder. The chemical composition analysis of the main valuable metals is shown in Table 1 below, where the content of each element is in mass percentage. The mass percentage of the NiMoO4 insoluble phase in the waste nickel-aluminum powder is 29%, and the scanning electron microscope NiMoO4 insoluble phase diagram is shown in Table 1 below. Figure 1 shown.

[0034] Table 1

[0035] element V Ni Al Mo Content, Wt% 0.23 10.25 53.86 8.96

[0036] The processing steps are as follows:

[0037] S1: Mix the flux sodium hydroxide with water to form a viscous slurry, then add scrap nickel aluminum powder to the viscous slurry, mix and form balls, and control the ball diameter within 1-3 cm. The number of moles of the added flux sodium hydroxide is 1.8 times the number of moles of molybdenum ions contained in the scrap nickel aluminum powder. Then, low-temperature calcination is carried out in a microwave environment. The calcination conditions are: microwave power 400W, calcination temperature 500℃, and treatment time 30min. A loose and porous calcined slag is obtained. See the photo. Figure 2 As shown;

[0038] S2: The calcined slag (spherical) is first added with water to prepare a hydrated calcined slag material, the liquid-solid ratio of the hydrated calcined slag material is 2.5 mL / g, and the hydrated calcined slag material is ultrasonically preactivated at room temperature (about 25°C), the ultrasonic power is 400 W, and the treatment time is 5 min; then, it is water-immersed, the ultrasonically preactivated hydrated calcined slag material is heated to 80°C, stirred for 50 min, and then solid-liquid separated to obtain molybdenum-containing leaching solution and nickel-aluminum leaching slag, respectively.

[0039] Analysis revealed that the majority of the molybdenum in the scrap nickel and aluminum powders entered the leachate, resulting in a molybdenum recovery rate of 99% and a nickel-aluminum leaching rate of 0.25%. The molybdenum mass fraction in the leachate, calculated based on the total mass of metals (excluding sodium), was 98.83%, indicating that the leachate was primarily molybdenum and of high purity.

[0040] The mass percentage content of nickel and aluminum in the leaching residue (calculated based on the total mass of metals contained in the leaching residue) is 98.3%.

[0041] Example 2

[0042] This embodiment provides a method for recovering molybdenum from waste nickel and aluminum powder for catalysts. The raw waste nickel and aluminum powder processed is the same as in Example 1. The processing steps are as follows:

[0043] S1: Potassium hydroxide (a flux) is mixed with water to form a viscous slurry. Scrap nickel and aluminum powder is then added to the viscous slurry, and the mixture is formed into balls with a diameter of 1 to 3 cm. The molar number of the added potassium hydroxide is 1.6 times the molar number of molybdenum ions contained in the scrap nickel and aluminum powder. The mixture is then calcined in a microwave environment at a microwave power of 800 W, a calcination temperature of 600° C., and a calcination time of 20 minutes to obtain a loose and porous slag.

[0044] S2: The calcined slag (spherical) is first added with water to prepare a hydrated calcined slag material, the liquid-solid ratio of the hydrated calcined slag material is 5.0 mL / g, and the hydrated calcined slag material is ultrasonically preactivated at room temperature (about 25°C), the ultrasonic power is 200 W, and the treatment time is 3 min; then, it is water-immersed, the ultrasonically preactivated hydrated calcined slag material is heated to 75°C, stirred for 60 min, and then solid-liquid separated to obtain molybdenum-containing leaching solution and nickel-aluminum leaching slag, respectively.

[0045] Analysis revealed that the majority of the molybdenum in the scrap nickel and aluminum powders entered the leachate, resulting in a molybdenum recovery rate of 97% and a nickel-aluminum leaching rate of 0.22%. The molybdenum mass fraction in the leachate, calculated based on the total mass of metals (excluding potassium), was 99.11%, indicating that the leachate was primarily molybdenum and of high purity.

[0046] The mass percentage content of nickel and aluminum in the leaching residue (calculated based on the total mass of metals contained in the leaching residue) is 98.8%.

[0047] Example 3

[0048] This embodiment provides a method for recovering molybdenum from waste nickel and aluminum powder for catalysts. The raw waste nickel and aluminum powder processed is the same as in Example 1. The processing steps are as follows:

[0049] S1: Mixing a flux of sodium hydroxide with water to form a viscous slurry, then adding scrap nickel and aluminum powder to the viscous slurry, mixing and forming balls, wherein the ball diameter is controlled within 1 to 3 cm, and the number of moles of the added flux of sodium hydroxide is 1.7 times the number of moles of molybdenum ions contained in the scrap nickel and aluminum powder. Then, low-temperature calcination is performed in a microwave environment under the following conditions: microwave power of 550 W, calcination temperature of 500° C., and treatment time of 25 minutes to obtain a loose and porous calcined slag;

[0050] S2: The calcined slag (spherical) is first added with water to prepare a hydrated calcined slag material, the liquid-solid ratio of the hydrated calcined slag material is 3.0 mL / g, and the hydrated calcined slag material is ultrasonically preactivated at room temperature (about 25°C), the ultrasonic power is 300 W, and the treatment time is 4 min; then, it is water-immersed, the ultrasonically preactivated hydrated calcined slag material is heated to 90°C, stirred for 30 min, and then solid-liquid separated to obtain molybdenum-containing leaching solution and nickel-aluminum leaching slag, respectively.

[0051] Analysis revealed that the majority of the molybdenum in the scrap nickel and aluminum powders entered the leachate, resulting in a molybdenum recovery rate of 98% and a nickel-aluminum leaching rate of 0.27%. The molybdenum mass fraction in the leachate, calculated based on the total mass of metals (excluding sodium), was 98.77%, indicating that the leachate was primarily molybdenum and of high purity.

[0052] The mass percentage content of nickel and aluminum in the leaching residue (calculated based on the total mass of metals contained in the leaching residue) is 98.5%.

[0053] Example 4

[0054] This embodiment provides a method for recovering molybdenum from waste nickel and aluminum powder for catalysts. The raw waste nickel and aluminum powder processed is the same as in Example 1. The processing steps are as follows:

[0055] S1: Potassium hydroxide (a flux) is mixed with water to form a viscous slurry. Scrap nickel and aluminum powder is then added to the viscous slurry, and the mixture is mixed to form balls. The ball diameter is controlled within 1 to 3 cm. The number of moles of potassium hydroxide added is 1.5 times the number of moles of molybdenum ions contained in the scrap nickel and aluminum powder. The mixture is then calcined in a microwave environment at a microwave power of 700 W, a calcination temperature of 400° C., and a calcination time of 20 minutes to obtain a loose and porous slag.

[0056] S2: The calcined slag (spherical) is first added with water to prepare a hydrated calcined slag material, the liquid-solid ratio of the hydrated calcined slag material is 4.0 mL / g, and the hydrated calcined slag material is ultrasonically preactivated at room temperature (about 25°C), the ultrasonic power is 300 W, and the treatment time is 4 min; then, it is water-immersed, the ultrasonically preactivated hydrated calcined slag material is heated to 80°C, stirred for 40 min, and then solid-liquid separated to obtain molybdenum-containing leaching solution and nickel-aluminum leaching slag, respectively.

[0057] Analysis revealed that the majority of the molybdenum in the scrap nickel and aluminum powders entered the leachate, resulting in a molybdenum recovery rate of 98% and a nickel-aluminum leaching rate of 0.22%. The molybdenum mass fraction in the leachate, calculated based on the total mass of metals (excluding potassium), was 98.63%, indicating that the leachate was primarily molybdenum and of high purity.

[0058] The mass percentage content of nickel and aluminum in the leaching residue (calculated based on the total mass of metals contained in the leaching residue) is 98.9%.

[0059] As can be seen from the above examples, the method of the present invention for treating waste nickel and aluminum powders achieves a molybdenum recovery rate of up to 99%, while simultaneously achieving a nickel and aluminum leaching rate of less than 0.3%. The resulting leached residue has a nickel and aluminum content exceeding 98% and is highly pure, allowing it to be directly used as a catalyst preparation raw material after simple processing. The resulting leachate is highly pure, significantly simplifying the subsequent molybdenum purification process.

[0060] Comparative Example 1

[0061] This comparative example provides a method for recovering molybdenum from waste nickel and aluminum powder used as a catalyst. The raw waste nickel and aluminum powder processed is the same as in Example 1. The processing steps are as follows:

[0062] S1: Mixing a flux of sodium hydroxide with water to form a viscous slurry, then adding scrap nickel and aluminum powder to the viscous slurry, mixing and forming balls, wherein the ball diameter is controlled within 1 to 3 cm, and the number of moles of the added flux of sodium hydroxide is 1.7 times the number of moles of molybdenum ions contained in the scrap nickel and aluminum powder. Then, low-temperature calcination is performed in a microwave environment under the following conditions: microwave power of 550 W, calcination temperature of 500° C., and treatment time of 25 minutes to obtain a loose and porous calcined slag;

[0063] S2: The calcined slag (spherical) was first added with water to prepare a hydrated calcined slag material. The liquid-solid ratio of the hydrated calcined slag material was 3.0 mL / g. The hydrated calcined slag material was directly subjected to water leaching treatment. The hydrated calcined slag material was heated to 90°C and stirred for 60 minutes. Then, the solid-liquid separation was performed to obtain a molybdenum-containing leaching solution and a nickel-aluminum leaching slag, respectively.

[0064] After testing and analysis, the molybdenum recovery rate of this comparative example is only 63%.

[0065] Comparative Example 2

[0066] This comparative example provides a method for recovering molybdenum from waste nickel and aluminum powder used as a catalyst. The raw waste nickel and aluminum powder processed is the same as in Example 1. The processing steps are as follows:

[0067] S1: Potassium hydroxide (a flux) is mixed with water to form a viscous slurry. Scrap nickel and aluminum powder is then added to the viscous slurry, and the mixture is formed into balls. The ball diameter is controlled within 1 to 3 cm. The number of moles of potassium hydroxide added is 1.6 times the number of moles of molybdenum ions contained in the scrap nickel and aluminum powder. The mixture is then calcined in a muffle furnace under the following conditions: the calcination temperature is set at 400° C. and the calcination time is controlled at 60 minutes to obtain calcined slag.

[0068] S2: The calcined slag (spherical) is first added with water to prepare a hydrated calcined slag material, the liquid-solid ratio of the hydrated calcined slag material is 5.0 mL / g, and the hydrated calcined slag material is ultrasonically preactivated at room temperature (about 25°C), the ultrasonic power is 200 W, and the treatment time is 3 min; then, it is water-immersed, the ultrasonically preactivated hydrated calcined slag material is heated to 75°C, stirred for 60 min, and then solid-liquid separated to obtain molybdenum-containing leaching solution and nickel-aluminum leaching slag, respectively.

[0069] The calcination temperature in step S1 of this comparative example was changed from 400°C to 500°C, 600°C, 700°C, and 800°C, respectively, with the treatment time remaining unchanged. Experiments were carried out to obtain the metal molybdenum recovery rates at the corresponding temperatures. The results are shown in Table 2.

[0070] Table 2

[0071] Calcination temperature, ℃ 400 500 600 700 800 Molybdenum recovery rate, % 26 32 41 58 72

[0072] It can be seen from the above table that when using a muffle furnace for roasting, it is difficult to decompose the insoluble molybdenum-containing phases such as NiMoO4 in the scrap nickel-aluminum powder under low temperature conditions, and the molybdenum recovery rate is low; it also shows that it is difficult to destroy its chemical bonds under the low-temperature roasting conditions of the muffle furnace. When the temperature is raised to 800 degrees, the molybdenum recovery rate is also less than 75%.

[0073] Experimental Example 1

[0074] This experiment mainly investigated the effect of different calcination treatment times on the molybdenum recovery rate. The raw materials treated were the same as those in Example 1.

[0075] The experimental steps are as follows:

[0076] S1: Potassium hydroxide (a flux) is mixed with water to form a viscous slurry. Scrap nickel and aluminum powder is then added to the viscous slurry, and the mixture is mixed to form balls. The ball diameter is controlled within 1 to 3 cm. The molar number of the added potassium hydroxide flux is 1.5 times the molar number of molybdenum ions contained in the scrap nickel and aluminum powder. The mixture is then subjected to a low-temperature calcination treatment in a microwave environment. The calcination conditions are: microwave power 700 W, calcination temperature 400°C, and treatment time is set to 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, and 40 min, respectively, to obtain loose and porous calcined slag.

[0077] The various types of calcined residues obtained in step S1 were subjected to ultrasonic preactivation and water leaching, using the same process steps as step S2 in Example 4 of the present invention. A molybdenum-containing leachate and a nickel-aluminum leached residue were obtained, and the molybdenum recovery rate was calculated. The specific results are shown in Table 3.

[0078] Table 3

[0079] Calcination time, min 10 15 20 25 30 35 40 Molybdenum recovery rate, % 43 68 98 98 99 79 68

[0080] From the above experiments, it can be seen that during microwave low-temperature roasting, the roasting time has a significant effect on the leaching of molybdenum. Too short or too long a time is not conducive to the dissolution of molybdenum in waste nickel-aluminum powder. Too short a time will result in incomplete roasting. Too long a time will easily promote the reaction of soluble molybdenum-containing compounds with nickel to form new insoluble Ni-Mo-O and other phases. Therefore, controlling the roasting time is very critical. The preferred roasting time of the present invention is controlled to 20 to 30 minutes.

[0081] The above examples illustrate that the method of the present invention can achieve effective leaching of molybdenum from insoluble NiMoO4 in scrap nickel-aluminum powder for catalysts, and significantly improve the recovery efficiency of molybdenum; the obtained leached residue has high purity and can be directly used as a raw material for catalyst preparation after simple treatment, thereby achieving true reuse and reducing the processing cost of the overall process.

[0082] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or any direct or indirect application in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for recovering molybdenum from waste nickel and aluminum powder for catalyst, characterized in that: Including steps: S1: mixing waste nickel and aluminum powder, a flux and water to form balls, wherein the ball diameter is controlled to be 1 to 3 cm, and then roasting in a microwave environment to obtain roasted slag; wherein the roasting conditions for the microwave roasting are: microwave power of 400 to 800 W, roasting temperature of 400 to 600° C., and roasting time of 20 to 30 minutes; the flux is sodium hydroxide and / or potassium hydroxide; S2: The roasted slag is pre-activated by ultrasonic wave, then treated with water, and then solid-liquid separation is performed to obtain molybdenum-containing leachate and nickel-aluminum leachate slag respectively; The molybdenum element in the waste nickel-aluminum powder mainly exists in the form of NiMoO4 insoluble phase.

2. The method according to claim 1, characterized in that The molar number of the flux is 1.2 to 2.0 times the molar number of molybdenum ions contained in the waste nickel-aluminum powder.

3. The method according to claim 2, characterized in that The molar number of the flux is 1.5 to 1.8 times the molar number of molybdenum ions contained in the waste nickel-aluminum powder.

4. The method according to claim 1, wherein The ultrasonic pre-activation comprises: treating the calcined slag with ultrasonic waves at room temperature, with an ultrasonic power of 200 to 400 W and a treatment time of 3 to 5 minutes.

5. The method according to claim 4, wherein Before the calcined slag is treated with ultrasound, water is first added to prepare a water-containing calcined slag material, and the liquid-to-solid ratio of the water-containing calcined slag material is 2.5-5.0 mL / g.

6. The method according to claim 1, wherein The water immersion treatment comprises: heating the water-containing roasted slag material after ultrasonic pre-activation to 75-90° C. and stirring for 30-60 minutes.

7. The method according to claim 1, characterized in that The mass percentage content of metallic molybdenum in the molybdenum-containing leachate is ≥98%.

8. The method according to claim 1, characterized in that The mass percentage content of nickel and aluminum in the nickel and aluminum leaching residue is ≥98%.

Images