Molybdenum oxide material for molybdenum powder and preparation method thereof

Abstract

The present invention provides a molybdenum oxide material for molybdenum powder and a preparation method thereof. The method comprises laying ammonium dimolybdate material in a material boat, then placing the material boat containing the ammonium dimolybdate material in a roasting furnace, sealing the roasting furnace and evacuating the furnace, and maintaining the temperature at 350-720°C for 60-420 minutes; after the end of the heat preservation, the molybdenum oxide material for molybdenum powder is obtained. The molybdenum oxide material for molybdenum powder comprises a MoO3 crystal phase and a MoO2 crystal phase, or comprises a MoO3 crystal phase and a Mo4O 11 This method features a short process flow, easy and precise control of process parameters, and a stable process, making it suitable for industrial production. The molybdenum content in this material is 66.67% higher than the theoretical molybdenum content of pure molybdenum trioxide, making it suitable as a high-quality pure molybdenum oxide raw material for preparing molybdenum powder. Using this material as a raw material for preparing molybdenum powder has the advantages of low hydrogen consumption during reduction and high activity.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical raw materials and relates to a molybdenum oxide material for molybdenum powder, and in particular to a molybdenum oxide material for molybdenum powder and a preparation method thereof. Background Art

[0002] With the rapid advancement of molybdenum metallurgical technology, competition in the molybdenum production technology market is becoming increasingly fierce. Molybdenum's application areas are gradually expanding, and the market demand for a wider range of molybdenum chemical products is increasing, with increasingly stringent requirements for molybdenum product quality and specifications. In response, molybdenum chemical production technology is keeping pace with the times, developing higher-quality products and developing product preparation processes with shorter processes, simpler operations, and more stable and reliable performance to meet market demands.

[0003] High-quality pure molybdenum oxide for molybdenum powder is a new variety of pure molybdenum oxide. It is developed due to the need to change the raw materials for molybdenum powder preparation under environmental pressure and the quality requirements for pure molybdenum oxide raised with the development of molybdenum powder preparation technology.

[0004] High-quality pure molybdenum oxide for molybdenum powder is prepared by using ammonium molybdate as raw material, which is decomposed into ammonia, water vapor and molybdenum trioxide at a certain temperature. The main occurrence states of metallic molybdenum in high-quality pure molybdenum oxide for molybdenum powder are MoO3, MoO2 and Mo4O 11 It has the characteristics of low oxygen content and high molybdenum content, and exhibits the advantages of high reduction activity and low energy consumption in molybdenum powder preparation.

[0005] The existing technology for preparing molybdenum powder using high-quality pure molybdenum oxide has the following main defects:

[0006] First, the existing preparation method has a complex process flow and it is difficult to accurately control the process parameters, resulting in poor process stability, which in turn makes it difficult to adapt to industrial production.

[0007] Second, when ammonium molybdate is roasted to produce molybdenum oxide, air needs to be injected into the roasting furnace to remove the ammonia and water vapor produced during the roasting process. Air containing ammonia and water vapor pollutes the environment, so ammonia in the exhaust gas needs to be recovered. However, due to the small differences in the physical and chemical properties of nitrogen, oxygen, water vapor, and ammonia contained in the exhaust gas, it is difficult to completely separate ammonia from the other gases, resulting in high waste gas treatment costs and the generation of secondary pollutants.

[0008] From the above analysis, it can be seen that inventing a stable and pollution-free method for preparing high-quality pure molybdenum oxide for molybdenum powder is urgent in order to meet the needs of industrial production of high-quality pure molybdenum oxide for molybdenum powder and the raw material market. Summary of the Invention

[0009] In view of the defects and shortcomings of the prior art, the purpose of the present invention is to provide a molybdenum oxide material for molybdenum powder and a preparation method thereof, so as to solve the technical problem that the preparation process of the molybdenum oxide material for molybdenum powder in the prior art is complex and unstable.

[0010] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0011] A method for preparing a molybdenum oxide material for molybdenum powder comprises the following steps: placing ammonium dimolybdate material in a material boat, then placing the material boat containing the ammonium dimolybdate material in a roasting furnace, sealing the roasting furnace and evacuating the furnace, and maintaining the temperature at 350-720°C for 60-420 minutes; after the end of the heat preservation, taking out the material to obtain the molybdenum oxide material for molybdenum powder.

[0012] The present invention also has the following technical features:

[0013] Specifically, during the insulation process, the water temperature at the ammonia recovery inlet of the roasting furnace is maintained at 10-25° C. to condense and recover ammonia gas.

[0014] Specifically, during the heat preservation process, the vacuum degree in the roasting furnace is maintained at 0.02Mpa to 0.09Mpa.

[0015] Specifically, the laying density of ammonium dimolybdate material in the material boat is 0.7g / cm 2 ~2.3g / cm 2 .

[0016] The present invention provides a molybdenum oxide material for molybdenum powder, which is prepared by the above-mentioned method for preparing the molybdenum oxide material for molybdenum powder; the molybdenum oxide material for molybdenum powder comprises a MoO3 crystal phase and a MoO2 crystal phase, or comprises a MoO3 crystal phase and a Mo4O 11 Crystal phase.

[0017] Specifically, the molybdenum oxide material for molybdenum powder contains a MoO3 crystal phase with a phase content of 90.9wt.% and a MoO2 crystal phase with a phase content of 9.1wt.%, or contains a MoO3 crystal phase with a phase content of 56.11wt.% and a Mo4O crystal phase with a phase content of 43.89wt.%. 11 The crystalline phase contains 65.6 wt.% of MoO3 and 34.4 wt.% of Mo4O. 11 Crystal phase.

[0018] Specifically, the bulk density of the molybdenum oxide material used for the molybdenum powder is 1.36 g / cm 3 ~1.37g / cm 3 .

[0019] Specifically, the molybdenum oxide material used for the molybdenum powder has a Fisher particle size of 12.5 μm to 12.6 μm.

[0020] The beneficial technical effects of the present invention compared with the prior art are as follows:

[0021] (I) The method for preparing the molybdenum oxide material for molybdenum powder of the present invention has a short process flow, easy and precise control of process parameters, stable process, and is suitable for industrial production.

[0022] (II) The method for preparing the molybdenum oxide material for molybdenum powder of the present invention transfers ammonia and water vapor to the outside of the roasting furnace by vacuuming, and simultaneously condenses the ammonia and water vapor to form ammonia water by shell and tube condensation, thereby avoiding the phenomenon that ammonia-containing waste gas is difficult to treat due to ammonia and water vapor carried in the air, and also avoids the generation of secondary pollutants in dilute ammonia water, thereby achieving the emission of no ammonia-containing waste liquid and waste gas.

[0023] (III) The molybdenum oxide material for molybdenum powder of the present invention has a molybdenum content higher than the theoretical molybdenum content of pure molybdenum trioxide by 66.67%, and is suitable as a high-quality pure molybdenum oxide raw material for preparing molybdenum powder. Using this material as a raw material for preparing molybdenum powder has the advantages of low hydrogen consumption during reduction and high activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The figure is a flow chart of a method for preparing molybdenum oxide material for molybdenum powder.

[0025] Figure 2 This is an SEM image of the molybdenum oxide material for molybdenum powder prepared in Example 1.

[0026] Figure 3 This is the XRD pattern of the molybdenum oxide material for molybdenum powder prepared in Example 1.

[0027] Figure 4 This is an SEM image of the molybdenum oxide material for molybdenum powder prepared in Example 2.

[0028] Figure 5 This is the XRD pattern of the molybdenum oxide material for molybdenum powder prepared in Example 2.

[0029] Figure 6 This is an SEM image of the molybdenum oxide material for molybdenum powder prepared in Example 3.

[0030] Figure 7 This is the XRD pattern of the molybdenum oxide material for molybdenum powder prepared in Example 3.

[0031] The technical solution of the present invention is further described below in conjunction with embodiments. DETAILED DESCRIPTION

[0032] It should be noted that all raw materials and equipment used in the present invention, unless otherwise specified, are raw materials and equipment known in the art. For example, the roasting furnace adopts a roasting furnace known in the prior art, and the ammonia recovery inlet of the roasting furnace is a shell and tube condensation ammonia recovery inlet.

[0033] In accordance with the above technical solution, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0034] Example 1:

[0035] This embodiment provides a method for preparing molybdenum oxide material for molybdenum powder. Figure 1 As shown, the method specifically includes the following processes:

[0036] The ammonium dimolybdate material was pressed at 0.7 g / cm 2 The ammonium dimolybdate material is evenly laid in the material boat at a density of 10000 g / m2. The material boat containing the ammonium dimolybdate material is then placed in a roasting furnace. The roasting furnace is sealed and evacuated. The temperature is raised to 350°C and then held for 60 minutes. During the holding process, the vacuum degree in the roasting furnace is maintained at 0.02 MPa, and the water temperature at the ammonia recovery inlet of the roasting furnace is maintained at 10°C. After the holding period is completed, the temperature is cooled to room temperature along with the furnace, and the material taken out is the molybdenum oxide material for molybdenum powder.

[0037] In this embodiment, the ammonia content in the gas discharged by the water circulation vacuum pump is 7 mg / m 3 , which is less than the ammonia emission limit of 10mg / m3 specified in the national standard GB31573-2015 3 .

[0038] In this embodiment, the SEM image of the molybdenum powder molybdenum oxide material is as follows: Figure 2 As shown, from Figure 2 It can be seen that the particles of the molybdenum oxide material used in the molybdenum powder are irregular blocks, the particles are non-agglomerated and evenly distributed, and the size is about 200μm.

[0039] In this embodiment, the XRD pattern of the molybdenum powder molybdenum oxide material is as follows: Figure 3 As shown by Figure 3 It can be seen that the molybdenum oxide material for molybdenum powder contains MoO3 crystal phase and MoO2 crystal phase, wherein the mass content of MoO3 crystal phase is 90.9%, and the mass content of MoO2 crystal phase is 9.1%.

[0040] Example 2:

[0041] This embodiment provides a method for preparing molybdenum oxide material for molybdenum powder, which specifically includes the following steps:

[0042] The ammonium dimolybdate material was pressed at 2.3 g / cm 2 The ammonium dimolybdate material is evenly laid in the boat. The boat containing the ammonium dimolybdate material is then placed in a roasting furnace. The roasting furnace is sealed and evacuated. The temperature is raised to 720°C and then held for 420 minutes. During the holding process, the vacuum in the roasting furnace is maintained at 0.09 MPa, and the water temperature at the ammonia recovery inlet of the roasting furnace is maintained at 25°C. After the holding period is completed, the temperature is cooled to room temperature, and the material removed is the molybdenum oxide material for molybdenum powder.

[0043] In this embodiment, the ammonia content in the gas discharged by the water circulation vacuum pump is 9 mg / m 3 , which is less than the ammonia emission limit of 10mg / m3 specified in the national standard GB31573-2015 3 , indicating that this method produces few pollutants and is environmentally friendly.

[0044] In this embodiment, the SEM image of the molybdenum powder molybdenum oxide material is as follows: Figure 4 As shown, from Figure 4 It can be seen that the particles of the molybdenum oxide material used in the molybdenum powder are irregular blocks, the particles are non-agglomerated and evenly distributed, and the size is about 200μm.

[0045] In this embodiment, the XRD pattern of the molybdenum powder molybdenum oxide material is as follows: Figure 5 As shown by Figure 5 It can be seen that the molybdenum oxide material for molybdenum powder contains MoO3 crystal phase and Mo4O 11 The mass content of MoO3 crystal phase is 56.11%, and the mass content of Mo4O 11 The mass content of the crystalline phase is 43.89%.

[0046] Example 3:

[0047] This embodiment provides a method for preparing molybdenum oxide material for molybdenum powder, which specifically includes the following steps:

[0048] The ammonium dimolybdate material was pressed at 1.5 g / cm 2 The ammonium dimolybdate material is evenly laid in the material boat at a density of 10000 g / m2. The material boat containing the ammonium dimolybdate material is then placed in a roasting furnace. The roasting furnace is sealed and evacuated. The temperature is raised to 450°C and then held for 240 minutes. During the holding process, the vacuum degree in the roasting furnace is maintained at 0.05 MPa, and the water temperature at the ammonia recovery inlet of the roasting furnace is maintained at 16°C. After the holding period is completed, the temperature is cooled to room temperature along with the furnace, and the material taken out is the molybdenum oxide material for molybdenum powder.

[0049] In this embodiment, the ammonia content in the gas discharged by the water circulation vacuum pump is 7 mg / m 3 , which is less than the ammonia emission limit of 10mg / m3 specified in the national standard GB31573-2015 3, indicating that this method produces few pollutants and is environmentally friendly.

[0050] In this embodiment, the SEM image of the molybdenum powder molybdenum oxide material is as follows: Figure 6 As shown, from Figure 6 It can be seen that the particles of the molybdenum oxide material used in the molybdenum powder are irregular blocks, the particles are non-agglomerated and evenly distributed, and the size is about 200μm.

[0051] In this embodiment, the XRD pattern of the molybdenum powder molybdenum oxide material is as follows: Figure 7 As shown by Figure 7 It can be seen that the molybdenum oxide material for molybdenum powder contains MoO3 crystal phase and Mo4O 11 The mass content of MoO3 crystal phase is 65.6%, and the mass content of Mo4O 11 The mass content of the crystalline phase is 34.4%.

[0052] In this example, the technical indicators of the molybdenum oxide materials for molybdenum powder prepared in Examples 1 to 3 were analyzed, and the results are shown in Table 1.

[0053] Table 1 Technical indicators of molybdenum oxide materials for molybdenum powder prepared in Examples 1 to 3

[0054]

[0055]

[0056] As can be seen from Table 1, the molybdenum content of the molybdenum oxide materials used for molybdenum powder in Examples 1, 2, and 3 is 67.43%, 67.50%, and 67.42%, respectively. The molybdenum content is similar, but all are greater than the theoretical content of 66.67% of pure molybdenum trioxide. The molybdenum content of other elements remains basically unchanged. The bulk density is 1.36 g / cm 3 , 1.37g / cm 3 and 1.36 g / cm 3 The bulk density and the Fisher particle size of the molybdenum oxide materials for molybdenum powder prepared in the three embodiments are very close, indicating that the preparation method of the present invention has good reproducibility and consistency and is suitable for industrial production.

Claims

1. A method for preparing molybdenum oxide material for molybdenum powder, characterized in that: The method specifically includes the following steps: placing ammonium dimolybdate material in a material boat, then placing the material boat containing the ammonium dimolybdate material in a roasting furnace, sealing the roasting furnace and evacuating the furnace, and maintaining the temperature at 350-720°C for 60-420 minutes; after the end of the heat preservation, taking out the material to obtain a molybdenum oxide material for molybdenum powder; During the insulation process, the water temperature at the ammonia recovery inlet of the roasting furnace is maintained at 10-25°C, and ammonia is recovered by condensation; During the insulation process, the vacuum degree in the roasting furnace is maintained at 0.02Mpa~0.09Mpa; The laying density of ammonium dimolybdate material in the material boat is 0.7g / cm 2 ~2.3g / cm 2 ; The molybdenum content in the molybdenum oxide material used for the molybdenum powder can reach 67.50wt.%; The molybdenum oxide material for molybdenum powder contains MoO3 crystal phase and MoO2 crystal phase, or contains MoO3 crystal phase and Mo4O 11 crystal phase; The molybdenum oxide material for molybdenum powder contains a MoO3 crystal phase with a phase content of 90.9wt.% and a MoO2 crystal phase with a phase content of 9.1wt.%, or contains a MoO3 crystal phase with a phase content of 56.11wt.% and a Mo4O crystal phase with a phase content of 43.89wt.%. 11 The crystalline phase contains 65.6 wt.% of MoO3 and 34.4 wt.% of Mo4O. 11 crystal phase; The bulk density of the molybdenum oxide material used for the molybdenum powder is 1.36 g / cm 3 ~1.37g / cm 3 ; The Fisher grain size of the molybdenum oxide material used for the molybdenum powder is 12.5 μm to 12.6 μm.

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