Preparation method of rare earth silicate

Abstract

The invention relates to the technical field of preparation of rare earth silicate, in particular to a preparation method of rare earth silicate. The rare earth silicate is prepared by uniformly mixing and roasting rare earth carbonate and diatomite. According to the preparation method of the rare earth silicate, the diatomite is adopted as a silicon source for the first time, compared with silicon dioxide, soluble silicon-containing inorganic salt or organic compounds (such as sodium silicate and tetraethoxysilane) and other silicon sources, the diatomite has the advantage of low price, and the prepared rare earth silicate has good chemical stability and low thermal conductivity and can be used for preparing the rare earth silicate. The method can be widely used in the fields of coatings and ceramics.

Description

Technical Field

[0001] The present invention relates to the technical field of rare earth silicate preparation, and particularly to a method for preparing rare earth silicate. Background Art

[0002] Diatomite is a biogenic siliceous sedimentary rock, which is mainly composed of the remains of ancient diatoms. Its chemical composition is mainly amorphous SiO2, with a content often exceeding 70%. Due to its strong adsorption capacity, low thermal conductivity, and good chemical stability, it is widely used in light industry, food, chemical industry, building materials, petroleum, medicine, high-grade highway construction and other fields.

[0003] Rare earth silicate has good thermal stability and chemical stability, and is widely used in thermal insulation coatings, environmental barrier coating materials, and functional ceramics. With the in-depth research on rare earth silicate, its application advantages in refractory materials are gradually emerging. At present, the silicon sources for preparing rare earth silicate powder are mainly silicon oxide and soluble silicon-containing inorganic salts or organic compounds (such as sodium silicate, tetraethyl orthosilicate). There is no report on directly using the inorganic silicate mineral - diatomite to prepare rare earth silicate powder.

[0004] The invention patent with the publication number CN112029502A discloses a lanthanum silicate phosphor powder material with apatite structure, its preparation method and application. Specifically, a co-precipitation method using tetraethyl orthosilicate as the raw material is adopted to prepare the lanthanum silicate phosphor powder material with apatite structure. This method can successfully prepare a high-performance phosphor material without impurity phases, but it requires tetraethyl orthosilicate as the raw material, with high cost and high risk factor.

[0005] The invention patent with the publication number CN 117285338 A discloses a super-high porosity high-entropy rare earth silicate with good high-temperature resistance and its preparation method. Using rare earth oxides and silicon oxide powder as raw materials, ceramic slurry is prepared with water as the dispersion medium, a dispersant is added to make the slurry particles disperse evenly, then a foaming agent is added and rapidly stirred to foam, and then injection molding and low-temperature freezing are carried out. Then vacuum drying and demolding are carried out. Finally, high-temperature sintering is carried out in a muffle furnace to prepare a porous high-entropy rare earth silicate high-temperature thermal insulation material. This method has a complex process, and the use of dispersants and foaming agents is required, with high cost and difficulty in industrial scale-up.

[0006] The invention patent with the publication number CN 106342076 B discloses a preparation method of composite rare earth silicate powder. Using a soluble salt containing RE element or a solution containing RE ions and a soluble silicon source with a pH value lower than 4 as raw materials, a hydrothermal reaction is carried out at 130°C - 450°C to obtain a precipitate, which is washed, centrifuged and then dried, and calcined at a temperature above 1400°C for more than 5 hours and ground to obtain the composite rare earth silicate powder. This technology requires hydrothermal treatment, with high energy consumption, difficult filtration, requires centrifugal separation, and is not easy to achieve process amplification. Summary of the Invention

[0007] In view of this, the purpose of the present invention is to provide a preparation method of rare earth silicate, directly using diatomite and rare earth carbonate to prepare rare earth silicate by solid-phase method.

[0008] To achieve the above purpose, the present invention provides the following solutions:

[0009] The present invention provides a preparation method of rare earth silicate, which is obtained by roasting the mixture of rare earth carbonate and diatomite evenly.

[0010] The present invention also provides a rare earth silicate prepared by the above preparation method.

[0011] The present invention also provides the application of the above rare earth silicate in the preparation of refractory materials.

[0012] The present invention discloses the following technical effects:

[0013] The present invention provides a preparation method of rare earth silicate. For the first time, diatomite is used as the silicon source. Compared with silicon sources such as silicon dioxide, soluble inorganic salts or organic compounds containing silicon (such as sodium silicate, tetraethyl orthosilicate), it has the advantage of low price. The prepared rare earth silicate has good chemical stability and low thermal conductivity, and can be widely used in fields such as coatings and ceramics. Brief Description of the Drawings

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0015] Figure 1 XRD pattern of the rare earth silicate prepared in Example 1. Detailed Description of the Embodiments

[0016] The various exemplary embodiments of the present invention will be described in detail below. This detailed description should not be construed as a limitation on the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0017] It should be understood that the terms used in the present invention are only for describing particular embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0018] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0019] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0020] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0021] In the present invention, REO represents rare earth oxide.

[0022] The present invention provides a method for preparing rare earth silicate, which directly uses diatomite as a raw material to prepare rare earth silicate by a solid-phase method, specifically including the following steps:

[0023] Mix rare earth carbonate and diatomite evenly and then calcine to obtain rare earth silicate.

[0024] In a preferred embodiment of the present invention, the rare earth element in the rare earth carbonate is at least one of lanthanum, cerium, yttrium, and ytterbium.

[0025] In a preferred embodiment of the present invention, the content of SiO2 in the diatomite is not less than 80 wt%; preferably, the content of SiO2 in the diatomite is not less than 85%; more preferably, the content of SiO2 is not less than 90%.

[0026] In a preferred embodiment of the present invention, based on REO, the molar ratio of SiO2 in the diatomaceous earth to the rare earth ions in the rare earth carbonate is (1-2):1.

[0027] In a preferred embodiment of the present invention, the temperature of the roasting is 1200°C - 1400°C; preferably, the temperature of the roasting is 1250°C - 1400°C.

[0028] In a preferred embodiment of the present invention, the time of the roasting is 120 min - 240 min.

[0029] The present invention also provides a rare earth silicate prepared by the above-mentioned preparation method.

[0030] The present invention also provides the application of the above-mentioned rare earth silicate in the preparation of refractory materials.

[0031] The technical solutions of the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are all purchased from commercial channels or have been made public.

[0032] The test methods involved in the present invention:

[0033] X-ray diffraction: The test is carried out using an X-ray powder diffractometer (model: X Pert PRO) from PANalytical of the Netherlands.

[0034] Thermal conductivity: The test is carried out using a thermal conductivity meter (model: TPS2500S) from Hot Disk of Sweden.

[0035] The technical solutions provided by the present invention will be described in detail below in conjunction with the examples, but they should not be construed as limiting the scope of protection of the present invention.

[0036] Example 1

[0037] Lanthanum carbonate (REO = 47.8%) and diatomaceous earth with a silica content of 85% were mixed evenly at a mass ratio of 1:9.64, roasted at 1250°C for 160 min, and lanthanum silicate was obtained, with a thermal conductivity of 0.34 W / m·K.

[0038] Figure 1 This is the XRD pattern of the lanthanum silicate prepared in Example 1. From Figure 1 It can be known that lanthanum monosilicate with good crystal form can be prepared using diatomaceous earth as the raw material.

[0039] Example 2

[0040] Mix yttrium carbonate (REO = 45.0%) and diatomaceous earth with 85% silica content evenly at a mass ratio of 1:5.48, and calcine at 1400 °C for 120 min to obtain yttrium silicate.

[0041] Example 3

[0042] Mix ytterbium carbonate (REO = 48.8%) and diatomaceous earth with 90% silica content evenly at a mass ratio of 1:3.465, and calcine at 1350 °C for 180 min to obtain ytterbium silicate.

[0043] Using the rare earth silicate prepared by the present invention to prepare refractory materials can achieve the same technical effects as the rare earth silicate obtained by purchase. This is because the main components of diatomaceous earth are amorphous silica above 85% and some iron, calcium, magnesium, aluminum and organic substances. During the calcination process, the organic substances decompose. Although there is still a small amount of iron, calcium, magnesium and aluminum that cannot be removed, the oxides of elements such as calcium, magnesium and aluminum are also indispensable elements in refractory materials. For example, magnesium oxide has a very high melting point and good high-temperature resistance, especially strong resistance to alkaline slag erosion, and calcium oxide can improve the high-temperature performance and slag resistance of refractory materials.

[0044] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing rare earth silicate, characterized in that, The rare earth carbonate and diatomite are mixed evenly and then calcined to obtain rare earth silicate.

2. The preparation method of rare earth silicate according to claim 1, characterized in that, The rare earth element in the rare earth carbonate is at least one of lanthanum, cerium, yttrium, and ytterbium.

3. The preparation method of rare earth silicate according to claim 1, characterized in that, The content of SiO2 in the diatomite is not less than 80 wt%.

4. The preparation method of rare earth silicate according to claim 1, characterized in that, Based on REO, the molar ratio of SiO2 in the diatomite to the rare earth ions in the rare earth carbonate is (1-2):

1.

5. The preparation method of rare earth silicate according to claim 1, characterized in that, The temperature of the calcination is 1200°C - 1400°C.

6. The preparation method of rare earth silicate according to claim 1, characterized in that, The time of the calcination is 120 min - 240 min.

7. A rare earth silicate prepared by the preparation method according to any one of claims 1-6.

8. The application of the rare earth silicate according to claim 7 in the preparation of refractory materials.

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