A method for producing a niobium-containing pyrochlore

Abstract

The application provides a preparation method of a niobium-containing pyrochlore, and belongs to the technical field of niobium mineral resource utilization, and the preparation method comprises the following steps: mixing NaF, Nb2O5 and CaCO3 according to a molar ratio of 1:1:1, and sufficiently grinding in an agate mortar to obtain a first powder; pressing the first powder in S1 into a round cake sample under a pressure of 10-15 MPa and keeping the pressure for 5-10 min to obtain a first sample; placing the first sample in S2 in a corundum crucible, placing the corundum crucible in a drying box, and drying at 80-100 DEG C for 40-60 min; placing the dried corundum crucible in S3 in a horizontal tube furnace, heating to a sintering temperature, and keeping the temperature for 3-6 hours; taking out the corundum crucible after keeping the temperature in S4 and cooling with the furnace, and collecting a final product, the application can directly synthesize a single niobium-containing mineral pyrochlore through solid-phase sintering, and through research on the mineral properties and reactions of the single niobium-containing mineral pyrochlore, a research object is provided for subsequent beneficiation, metallurgy and other research.

Description

Technical Field

[0001] The present invention relates to the technical field of niobium ore resource utilization, in particular to a method for preparing niobium-containing pyrochlore. Background Art

[0002] Niobium is a strategic metal of high economic value. Its high melting point, superconductivity, and corrosion resistance make it widely used in metallurgy, superconducting materials, aerospace, and military applications. Niobium metal is primarily derived from niobium minerals, with pyrochlore being the primary niobium-producing mineral, containing over 50% niobium, making it a high-niobium-content mineral. However, niobium ferrocogenite is the most widely utilized niobium resource in my country, while pyrochlore accounts for a relatively low proportion. Niobium grades in these deposits are generally below 0.2%, with many even falling below the industrial grade of 0.02%.

[0003] Although small amounts of pyrochlore deposits exist in some areas of my country, there are currently no single pyrochlore beneficiation plants. Most pyrochlore deposits are co-existing ores with niobium, iron, and rare earth elements. Due to the diverse niobium minerals, fine particle size, stable niobium phases, and complex physical properties found in these deposits, the mature HF hydrometallurgical process is difficult to process. Niobium beneficiation and smelting are extremely challenging, resulting in low utilization value.

[0004] For a long time, polymetallic associated ores have been used to beneficiate iron and rare earth elements. However, due to limited research on fundamental issues such as niobium's occurrence and physical properties, key scientific challenges in niobium beneficiation and extraction have yet to be effectively addressed. To date, relatively little research has focused on complex niobium minerals, characterized by their complex chemical composition, diverse elemental diversity, widespread isomorphism, and the presence of multiple valence states for some elements. Due to the significant difficulty in beneficiation, it has been difficult to study the mineralogy and reactions of the single niobium-bearing mineral pyrochlore. Summary of the Invention

[0005] A technical problem to be solved by the present invention is that it is currently difficult to study niobium minerals in polymetallic associated ores by mineral selection, and it is therefore impossible to study the mineral properties and reactions of the niobium mineral pyrochlore.

[0006] To solve the above technical problems, the present disclosure provides a method for preparing niobium-containing pyrochlore, which comprises:

[0007] S1. NaF, Nb2O5 and CaCO3 are mixed in a molar ratio of 1:1:1, and fully ground in an agate mortar to obtain a first powder;

[0008] S2. Press the first powder in S1 into a round cake-shaped sample under a pressure of 10-15 MPa and maintain the pressure for 5-10 minutes to obtain a first sample;

[0009] S3, placing the first sample in S2 in a corundum crucible, and drying the corundum crucible in a drying oven at 80-100° C. for 40-60 min;

[0010] S4, placing the dried corundum crucible in S3 in a horizontal tube furnace, heating it to a sintering temperature, and keeping it warm for 3-6 hours;

[0011] S5. The corundum crucible kept warm in S4 is taken out after cooling with the furnace, and the final product is collected.

[0012] In some embodiments, in the aforementioned method for preparing niobium-containing pyrochlore, the mass fractions of the substances in the first powder S1 are CaCO3: 24.5%, Nb2O5: 65.2%, and NaF: 10.3%.

[0013] In some embodiments, in the aforementioned method for preparing niobium-containing pyrochlore, the diameter of the first sample in S2 is 10-12 mm.

[0014] In some embodiments, in the aforementioned method for preparing niobium-containing pyrochlore, high-purity argon gas is introduced into the S4 and S5 horizontal tube furnace environments for protection, and the high-purity argon gas flow rate is 800-1000 mL / min.

[0015] In some embodiments, in the aforementioned method for preparing niobium-containing pyrochlore, the horizontal tube furnace S4 is purged with high-purity argon for 20-30 minutes before heating.

[0016] In some embodiments, in the aforementioned method for preparing niobium-containing pyrochlore, the purity of the high-purity argon gas is ≥99.999%.

[0017] In some embodiments, in the aforementioned method for preparing niobium-containing pyrochlore, F in the first powder in S1 is released in the form of F2, NbF5, and HF; wherein, when the first powder is fully dried, the generation of HF can be reduced.

[0018] In some embodiments, in the aforementioned method for preparing niobium-containing pyrochlore, the sintering temperature in S4 is 1000°C-1300°C.

[0019] Through the above technical solution, the present invention provides a method for preparing niobium-containing pyrochlore. According to the pyrochlore structure, it can generally be expressed in the form of A2B2O6(O,F), where A can be an element such as Ca, Na, and B can be an element such as Nb, Ta, etc., and according to the existing analysis of the composition of polymetallic associated ores, it can be known that the structure of the finally prepared niobium-containing pyrochlore is CaNaNb2O6F. The present application can directly synthesize a single niobium-containing mineral pyrochlore by solid-phase sintering. Compared with complex niobium minerals in polymetallic associated ores, which have complex chemical compositions, a large number of elemental species, widespread isomorphism, and multiple valence states of some elements, mineral processing is simpler and more convenient for separation. In addition, the method of the present application can be used to study the mineral properties and reactions of the single niobium-containing mineral pyrochlore, providing research objects for subsequent mineral processing, metallurgy, and other research. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 XRD patterns of niobium-containing pyrochlore CaNaNb2O6F prepared in Example 1, Example 2, and Example 3;

[0021] Figure 2 This is a flow chart of a method for preparing niobium-containing pyrochlore according to this embodiment. DETAILED DESCRIPTION

[0022] Example 1:

[0023] In this embodiment, a method for preparing niobium-containing pyrochlore includes the following steps:

[0024] S1. NaF, Nb2O5 and CaCO3 are mixed in a molar ratio of 1:1:1 and a mass fraction of CaCO3: 24.5%, Nb2O5: 65.2%, and NaF: 10.3%, and the mixture is fully ground in an agate mortar to obtain a first powder;

[0025] S2. Pressing the first powder into a round cake-shaped sample with a diameter of 12 mm under a pressure of 10 MPa and maintaining the pressure for 10 minutes to obtain a first sample. The pressing is to increase the density, increase the contact area between the raw materials, and promote the occurrence of the solid-phase sintering reaction;

[0026] S3, then placing the first sample in a corundum crucible, and placing the crucible in a drying oven at 100° C. for 40 min;

[0027] S4. Place the corundum crucible in a tube furnace, introduce high-purity argon gas with a purity of ≥99.999% to purge the furnace tube for 20 minutes, heat the furnace tube to 1100°C at a heating rate of 5°C / min and keep the temperature for 300 minutes, and introduce high-purity argon gas for protection at a flow rate of 1000 mL / min.

[0028] S5. Set the horizontal tube furnace to cool down to room temperature at a rate of 5°C / min, while introducing high-purity argon gas for protection at a flow rate of 1000 mL / min.

[0029] Reference Attachment Figure 1 and attached Figure 2 All its peaks are consistent with the standard card (Ca,Na)2Nb2O6(OH,F) (PDF#85-0790), and no other miscellaneous peaks appear, indicating that it only contains pyrochlore phase.

[0030] Example 2:

[0031] In this embodiment, a method for preparing niobium-containing pyrochlore includes the following steps:

[0032] S1. NaF, Nb2O5 and CaCO3 are mixed in a molar ratio of 1:1:1 and a mass fraction of CaCO3: 24.5%, Nb2O5: 65.2%, and NaF: 10.3%, and the mixture is fully ground in an agate mortar to obtain a first powder;

[0033] S2. Pressing the first powder into a round cake-shaped sample with a diameter of 12 mm under a pressure of 12 MPa and maintaining the pressure for 10 minutes to obtain a first sample. The pressing is to increase the density, increase the contact area between the raw materials, and promote the occurrence of the solid-phase sintering reaction;

[0034] S3, then placing the first sample in a corundum crucible, and placing the crucible in a drying oven at 90° C. for 50 min;

[0035] S4. Place the corundum crucible in a tube furnace, introduce high-purity argon gas with a purity of ≥99.999% to purge the furnace tube for 25 minutes, heat the furnace to 1200°C at a heating rate of 5°C / min and keep the temperature for 240 minutes, and introduce high-purity argon gas for protection at a flow rate of 900 mL / min.

[0036] S5. Set the horizontal tube furnace to cool down to room temperature at a rate of 5°C / min, while introducing high-purity argon gas for protection at a flow rate of 900 mL / min.

[0037] Reference Attachment Figure 1 and attached Figure 2 All its peaks are consistent with the standard card (Ca,Na)2Nb2O6(OH,F) (PDF#85-0790), and no other miscellaneous peaks appear, indicating that it only contains pyrochlore phase.

[0038] Example 3:

[0039] In this embodiment, a method for preparing niobium-containing pyrochlore includes the following steps:

[0040] S1. NaF, Nb2O5 and CaCO3 are mixed in a molar ratio of 1:1:1 and a mass fraction of CaCO3: 24.5%, Nb2O5: 65.2%, and NaF: 10.3%, and the mixture is fully ground in an agate mortar to obtain a first powder;

[0041] S2. Pressing the first powder into a round cake-shaped sample with a diameter of 12 mm under a pressure of 12 MPa and maintaining the pressure for 10 minutes to obtain a first sample. The pressing is to increase the density, increase the contact area between the raw materials, and promote the occurrence of the solid-phase sintering reaction;

[0042] S3, then placing the first sample in a corundum crucible, and placing the crucible in a drying oven at 90° C. for 60 min;

[0043] S4. Place the corundum crucible in a tube furnace, introduce high-purity argon gas with a purity of ≥99.999% to purge the furnace tube for 30 minutes, heat the furnace tube to 1300°C at a heating rate of 5°C / min and keep the temperature for 210 minutes, and introduce high-purity argon gas for protection at a flow rate of 800 mL / min.

[0044] S5. Set the horizontal tube furnace to cool down to room temperature at a rate of 5°C / min, while introducing high-purity argon gas for protection at a flow rate of 800 mL / min.

[0045] Reference Attachment Figure 1 and attached Figure 2 All its peaks are consistent with the standard card (Ca,Na)2Nb2O6(OH,F) (PDF#85-0790), and no other miscellaneous peaks appear, indicating that it only contains pyrochlore phase.

[0046] The contents of the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. Various equivalent modifications of the present invention by those skilled in the art fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing niobium-containing pyrochlore, characterized in that: The following steps are involved: S1. NaF, Nb2O5 and CaCO3 are mixed in a molar ratio of 1:1:1, and fully ground in an agate mortar to obtain a first powder; S2. Press the first powder in S1 into a round cake-shaped sample under a pressure of 10-15 MPa and maintain the pressure for 5-10 minutes to obtain a first sample; S3, placing the first sample in S2 in a corundum crucible, and drying the corundum crucible in a drying oven at 80-100° C. for 40-60 min; S4, placing the dried corundum crucible in S3 in a horizontal tube furnace, heating it to a sintering temperature, and keeping it warm for 3-6 hours; S5. The corundum crucible kept warm in S4 is taken out after cooling with the furnace, and the final product is collected.

2. The method for preparing niobium-containing pyrochlore according to claim 1, characterized in that: S1 The mass fractions of the substances in the first powder are: CaCO3: 24.5%, Nb2O5: 65.2%, and NaF: 10.3%.

3. The method for preparing niobium-containing pyrochlore according to claim 1, wherein: The diameter of the first sample in S2 is 10-12 mm.

4. The method for preparing niobium-containing pyrochlore according to claim 1, wherein: High-purity argon gas was introduced into the horizontal tube furnace environment of S4 and S5 for protection, and the flow rate of the high-purity argon gas was 800-1000 mL / min.

5. The method for preparing niobium-containing pyrochlore according to claim 1, characterized in that: S4: Before heating the horizontal tube furnace, the horizontal tube furnace is purged with high-purity argon for 20-30 minutes.

6. The method for preparing niobium-containing pyrochlore according to claim 4 or 5, characterized in that: The purity of the high-purity argon gas is ≥99.999%.

7. The method for preparing niobium-containing pyrochlore according to claim 1, characterized in that: The F in the first powder in S1 leaves in the form of F2, NbF5 and HF; Wherein, when the first powder is fully dried, the generation of HF can be reduced.

8. The method for preparing niobium-containing pyrochlore according to claim 1, characterized in that: The sintering temperature in S4 is 1000°C-1300°C.

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