A method for preparing a Ni3S4 compound and its application

Abstract

The application relates to a preparation method of a Ni3S4 compound and application thereof, wherein the preparation method comprises the following steps: weighing required sulfur powder and nickel powder as reaction raw materials, wherein the molar ratio of the sulfur powder and the nickel powder is (1.2-1.6):1; grinding the reaction raw materials into mixed powder of the sulfur powder and the nickel powder under the atmosphere of inert gas; cleaning the mixed powder after the grinding treatment; vacuum drying the mixed powder after the cleaning treatment; putting the mixed powder after the vacuum drying treatment into a sintering furnace for sintering treatment to obtain the Ni3S4 compound; and cooling the Ni3S4 compound with the sintering furnace. The preparation method of the Ni3S4 compound provided by the application does not need smelting rolling, and the preparation process is simple; the raw material cost of the Ni3S4 compound obtained by the application is low; in addition, the molar ratio of the sulfur powder and the nickel powder is limited to a certain range, too much residual sulfur powder or nickel powder is avoided, and the prepared Ni3S4 compound with high purity is ensured.

Description

Technical Field

[0001] This invention relates to the field of materials chemistry, and more specifically, to a method for preparing a Ni3S4 compound and its application. Background Technology

[0002] In industries such as petroleum, metallurgy, power, and petrochemicals, flue gas treatment systems that use heavy oil or coal as the main industrial fuel, such as air preheaters, heat exchangers, economizers, flues, chimneys, and desulfurization devices in the low-temperature parts of boilers, commonly encounter situations where the sulfur content in the fuel is high. After combustion, SO2 is generated, some of which further generates SO3. When SO3 reaches the dew point temperature, it combines with water vapor to form H2SO4, changing from dilute to concentrated, causing corrosion of the equipment. This phenomenon is called "sulfuric acid dew point corrosion."

[0003] In the existing technology, 09CrCuSb steel contains Cr, Cu, and Sb elements. During service in a sulfuric acid environment, these elements are more likely to react first and form a passivation film on the steel surface, preventing corrosion. 09CrCuSb steel is a steel resistant to sulfuric acid dew point corrosion and is widely used in the manufacture of equipment such as coal-fired boilers, oil-fired boilers, coolers, and evaporators.

[0004] The prior art, patent CN105200349A, discloses a method for producing 09CrCuSb round steel resistant to sulfuric acid dew point corrosion, including the following steps: (1) reasonably determining the chemical composition and inclusion control level of the 09CrCuSb round steel; (2) converter; (3) LF furnace smelting; (4) VD vacuum refining; (5) continuous casting; (6) heating furnace; (7) billet casting; (8) high-pressure water descaling; (9) rolling process, etc.

[0005] However, 09CrCuSb steel also has the following disadvantages: high cost, complex preparation process, and corrosion resistance needs to be improved. Summary of the Invention

[0006] This invention provides a method for preparing Ni3S4 compound, which solves the technical problems of high cost, complex preparation process and low corrosion resistance of 09CrCuSb steel in the prior art.

[0007] A method for preparing a Ni3S4 compound, comprising the following steps:

[0008] Weigh out the required sulfur powder and nickel powder as reaction raw materials, wherein the molar ratio of sulfur powder to nickel powder is (1.2-1.6):1;

[0009] Grinding: The reactants are ground into a mixture of sulfur powder and nickel powder in an inert gas atmosphere;

[0010] Cleaning: The ground mixture is then cleaned.

[0011] Drying: The mixed powder after cleaning is placed in a vacuum drying oven for vacuum drying.

[0012] Sintering: The mixed powder after vacuum drying is placed in a sintering furnace for sintering to obtain Ni3S4 compound.

[0013] The method for preparing Ni3S4 compound provided by this invention, compared with the existing preparation process of 09CrCuSb steel, does not require smelting and rolling, and the preparation process is simple. Since 09CrCuSb steel contains chromium (Cr), copper (Cu) and the non-renewable rare metal antimony (Sb), its cost is high. On Earth, sulfur (S) and nickel (Ni) resources are relatively abundant. Therefore, the raw material cost of Ni3S4 compound obtained by this invention is low. In addition, limiting the molar ratio of sulfur powder and nickel powder to meet a certain range avoids excessive sulfur powder or nickel powder residue, ensuring the preparation of Ni3S4 compound with high purity.

[0014] Furthermore, the sintering treatment of the mixed powder after vacuum drying includes: cooling the mixed powder to room temperature in a vacuum drying oven, placing it in a crucible, and placing the crucible containing the mixed powder into a plasma activation sintering furnace for plasma activation sintering treatment.

[0015] The process conditions for the plasma-activated sintering treatment are as follows: the sintering temperature is between 900℃ and 1500℃, the sintering pressure is between 10MPa and 30MPa, and the sintering vacuum degree is ≤10. -1 Pa, the sintering time is between 5 min and 10 min.

[0016] This invention uses a mixture of sulfur powder and nickel powder that is activated by plasma to sinter. It has the technical advantages of rapid heating, short sintering time, and improved sintering efficiency of the mixture. It also improves the performance of the sintered body of the mixture, making the structure of the sintered body of the mixture fine, uniform and dense.

[0017] Further, the step of grinding the reaction raw materials into a mixed powder of sulfur powder and nickel powder under an inert gas atmosphere includes:

[0018] The reactants are placed in a ball mill jar, the ball mill jar is evacuated and filled with inert gas;

[0019] The ball mill jar containing the reaction raw materials is placed in a ball mill for ball milling.

[0020] This invention improves the dispersion of nickel powder and sulfur powder by ball milling the reaction raw materials, so that the nickel powder and sulfur powder are fully mixed, reducing the particle size of nickel powder and sulfur powder, thereby improving the formability and sintering properties of nickel powder and sulfur powder, reducing the sintering temperature, saving energy, and increasing the sintering density.

[0021] Furthermore, the ball milling time is 5h-50h.

[0022] This invention ensures that nickel powder and sulfur powder are fully ground and thoroughly mixed by limiting the ball milling time within a certain range.

[0023] Further, the step of cleaning the ground mixed powder includes:

[0024] The mixed powder is placed in a container containing acetone or ethanol for a first stirring and cleaning process.

[0025] The mixed powder is placed in a container filled with distilled water for a second stirring and washing process.

[0026] Since nickel powder and sulfur powder are insoluble in acetone, ethanol, or distilled water, this invention removes organic and inorganic impurities from the mixed powder by first washing it with acetone or ethanol and then with distilled water, thereby improving the purity of the reaction raw materials for preparing Ni3S4 compounds.

[0027] Furthermore, the first stirring and cleaning time is between 10 min and 60 min, the second stirring and cleaning time is between 5 min and 30 min; and / or, the temperature of the first stirring and cleaning is between 30℃ and 50℃.

[0028] In this embodiment of the invention, by limiting the temperature of the first stirring and cleaning, the cleaning effect of the mixed nickel powder and sulfur powder is improved, so that organic impurities are fully dissolved in acetone or ethanol solution, thereby improving the purity of the mixed nickel powder and sulfur powder.

[0029] Furthermore, the vacuum drying temperature is between 120℃ and 150℃, and the vacuum drying time is between 1 hour and 5 hours.

[0030] This invention ensures that the mixed powder of cleaned nickel powder and sulfur powder is fully dried by limiting the temperature and time of the vacuum drying process.

[0031] Furthermore, the particle size of both the sulfur powder and the nickel powder is ≤300μm, and / or the purity of both the sulfur powder and the nickel powder is ≥99%.

[0032] Furthermore, after the step of sintering the mixed powder in a sintering furnace to obtain the Ni3S4 compound, the method further includes: cooling: cooling the Ni3S4 compound along with the sintering furnace.

[0033] The present invention also provides an application of the Ni3S4 compound, wherein the Ni3S4 compound is obtained by the preparation method of the Ni3S4 compound described above, and the Ni3S4 compound is coated on the inner surface of a coal-fired boiler or an oil-fired boiler. Attached Figure Description

[0034] Figure 1 A schematic diagram of the process flow for preparing the Ni3S4 compound provided by the present invention;

[0035] Figure 2 A schematic diagram of the fracture morphology of Ni3S4 compound obtained by the preparation method of Ni3S4 compound provided by the present invention; Detailed Implementation

[0036] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the following description is provided in conjunction with the accompanying drawings. Figure 1-2 Specific embodiments of the present invention will be described in detail below.

[0037] See appendix Figure 1 This invention provides a method for preparing a Ni3S4 compound. The method for preparing the Ni3S4 compound includes the following steps:

[0038] Weigh out the required sulfur powder and nickel powder as reaction raw materials, wherein the molar ratio of sulfur powder to nickel powder is (1.2-1.6):1;

[0039] Grinding: The reaction raw materials are ground into a mixed powder of sulfur powder and nickel powder under an inert gas atmosphere;

[0040] Cleaning: The ground powder mixture is then cleaned.

[0041] Drying: Place the cleaned mixed powder into a vacuum drying oven for vacuum drying.

[0042] Sintering: The mixed powder after vacuum drying is placed into a sintering furnace for sintering to obtain Ni3S4 compound.

[0043] It should be noted that Ni3S4 compounds can exist in bulk, powder, filament, strip, or flake form. Ni is a corrosion-resistant metal, and Ni resources are relatively abundant.

[0044] It should be noted that grinding is carried out in an inert gas atmosphere to prevent the sulfur powder and nickel powder from oxidizing.

[0045] It should be noted that the material is cooled to room temperature along with the sintering furnace.

[0046] Preferably, the molar ratio of sulfur powder to nickel powder is (1.25-1.5):1; more preferably, the molar ratio of sulfur powder to nickel powder is (1.3-1.45):1.

[0047] The method for preparing Ni3S4 compound provided in this invention, compared with the prior art preparation process of 09CrCuSb steel, does not require smelting and rolling, and the preparation process is simple. Since 09CrCuSb steel contains Cr, Cu and the non-renewable rare metal Sb, its cost is high. On Earth, S and Ni resources are relatively abundant. Therefore, the raw material cost of Ni3S4 compound obtained by this invention is low. In addition, limiting the molar ratio of sulfur powder and nickel powder to meet a certain range avoids excessive sulfur powder or nickel powder residue, ensuring the preparation of Ni3S4 compound with high purity.

[0048] It should be noted that sintering types include conventional sintering, atmosphere pressure sintering, hot pressing sintering, microwave sintering, and plasma-activated sintering. Among them, the main characteristic of plasma-activated sintering is that it uses heating and surface activation to achieve ultra-fast densification sintering of materials. It has advantages such as fast heating rate, short sintering time, low sintering temperature, uniform heating, high production efficiency, and energy saving. In addition, due to the combined effect of plasma activation and rapid heating sintering, grain growth is suppressed, the microstructure of the original particles is maintained, thereby fundamentally improving the performance of the sintered body and making the final product have the characteristics of fine and uniform structure, maintaining the natural state of the raw materials, and high density.

[0049] In this embodiment of the invention, the mixed powder after vacuum drying is subjected to sintering treatment, specifically including: cooling the mixed powder to room temperature, placing it in a crucible, and placing the crucible containing the mixed powder into a plasma activation sintering furnace for plasma activation sintering treatment.

[0050] It should be noted that the crucible can be a graphite crucible, a corundum crucible, or a metal crucible, etc.

[0051] Therefore, the present invention uses a mixture of plasma-activated sintered sulfur powder and nickel powder, which has the technical effects of rapid heating, short sintering time, and improved sintering efficiency of the mixture. It also improves the performance of the sintered body of the mixture, making the structure of the sintered body of the mixture fine, uniform and dense.

[0052] Optionally, in this embodiment of the invention, the process conditions for plasma-activated sintering treatment can be: a sintering temperature between 900℃ and 1500℃, a sintering pressure between 10MPa and 30MPa, and a sintering vacuum degree ≤10. -1The sintering time is between 5 min and 10 min; preferably, the plasma-activated sintering process conditions can also be: sintering temperature between 1000℃ and 1400℃, sintering pressure between 15 MPa and 25 MPa, and sintering vacuum degree ≤ 10 MPa. -1 The sintering time is between 6 min and 9 min; more preferably, the process conditions for plasma-activated sintering treatment can also be: sintering temperature between 1100℃ and 1300℃, sintering pressure between 18 MPa and 22 MPa, and sintering vacuum degree ≤ 10 MPa. -1 Pa, sintering time is between 7 min and 8 min.

[0053] In this embodiment of the invention, the reactants are ground into a mixed powder of sulfur powder and nickel powder under an inert gas atmosphere, comprising:

[0054] The reaction materials are placed in a ball mill jar, the ball mill jar is evacuated and filled with inert gas;

[0055] Place the ball mill jar containing the reactants into the ball mill for ball milling.

[0056] It should be noted that there are no restrictions on the type of ball mill; it can be a short-cylinder ball mill, a long-cylinder ball mill, a tube mill, or a conical mill.

[0057] In this embodiment of the invention, ball milling of the reaction raw materials improves the dispersion of nickel powder and sulfur powder, ensuring thorough mixing of the nickel powder and sulfur powder, reducing the particle size of the nickel powder and sulfur powder, thereby improving the formability and sinterability of the nickel powder and sulfur powder, reducing the sintering temperature, saving energy, and also increasing the sintering density.

[0058] In this embodiment of the invention, optionally, the ball milling time is 5h-50h; preferably, the ball milling time can be 10h-40h; more preferably, the ball milling time can be 20h-30h.

[0059] In this embodiment of the invention, the ground mixed powder is cleaned, including:

[0060] The mixed powder is placed in a container containing acetone or ethanol for the first stirring and washing.

[0061] The mixed powder is placed in a container of distilled water for a second stirring and washing.

[0062] Since nickel powder and sulfur powder are insoluble in acetone, ethanol, or distilled water, this embodiment of the invention removes organic and inorganic impurities from the mixed powder by first washing it with acetone or ethanol and then with distilled water, thereby improving the purity of the reaction raw materials for preparing Ni3S4 compounds.

[0063] In this embodiment of the invention, optionally, the first stirring and cleaning time is between 10 min and 60 min, and the second stirring and cleaning time is between 5 min and 30 min; preferably, the first stirring and cleaning time is between 20 min and 50 min, and the second stirring and cleaning time is between 10 min and 25 min; more preferably, the first stirring and cleaning time is between 30 min and 40 min, and the second stirring and cleaning time is between 15 min and 20 min.

[0064] In this embodiment of the invention, by limiting the stirring and cleaning time, the cleaning effect of the mixed nickel powder and sulfur powder can be improved, so that impurities can be fully dissolved, thereby improving the purity of the mixed nickel powder and sulfur powder.

[0065] Optionally, the temperature of the first stirring and cleaning is between 30°C and 50°C; preferably, the temperature of the first stirring and cleaning is between 40°C and 50°C; more preferably, the temperature of the first stirring and cleaning is between 45°C and 50°C.

[0066] In this embodiment of the invention, by limiting the temperature of the first stirring and cleaning, the cleaning effect of the mixed nickel powder and sulfur powder is improved, so that organic impurities are fully dissolved in acetone or ethanol solution, thereby improving the purity of the mixed nickel powder and sulfur powder.

[0067] In this embodiment of the invention, the mixed powder after cleaning is subjected to vacuum drying. Specifically, the cleaned mixed powder is placed in a vacuum drying oven for drying. Optionally, the vacuum drying temperature is between 120℃ and 150℃, and the vacuum drying time is between 1 hour and 5 hours; preferably, the vacuum drying temperature is between 125℃ and 145℃, and the vacuum drying time is between 1.5 hours and 4.5 hours; more preferably, the vacuum drying temperature is between 130℃ and 140℃, and the vacuum drying time is between 2 hours and 4 hours.

[0068] In this embodiment of the invention, by limiting the temperature and time of the vacuum drying process, the mixed powder of cleaned nickel powder and sulfur powder is ensured to be fully dried.

[0069] In this embodiment of the invention, optionally, the particle size of both sulfur powder and nickel powder is ≤300μm; preferably, the particle size of both sulfur powder and nickel powder is ≤200μm; more preferably, the particle size of both sulfur powder and nickel powder is ≤100μm.

[0070] The embodiments of the present invention, by limiting the particle size of sulfur powder and nickel powder to meet certain conditions, are beneficial to saving ball milling time.

[0071] In this embodiment of the invention, optionally, the purity of both sulfur powder and nickel powder is ≥99%; preferably, the purity of both sulfur powder and nickel powder is ≥99.5%; more preferably, the purity of both sulfur powder and nickel powder is ≥99.9%.

[0072] The embodiments of the present invention improve the purity of the prepared Ni3S4 compound by limiting the purity of sulfur powder and nickel powder to meet certain conditions.

[0073] In this embodiment of the invention, after the step of sintering the mixed powder in a sintering furnace to obtain the Ni3S4 compound, the method further includes: cooling: cooling the Ni3S4 compound along with the sintering furnace.

[0074] This invention also provides an application of the Ni3S4 compound. The Ni3S4 compound is obtained by the above-mentioned preparation method. The Ni3S4 compound is coated on the inner surface of a coal-fired boiler or an oil-fired boiler to improve the corrosion resistance of the inner surface of the coal-fired boiler or an oil-fired boiler, extend the service life of the coal-fired boiler or an oil-fired boiler, and improve the efficiency of the coal-fired boiler or an oil-fired boiler.

[0075] To further illustrate the present invention, the Ni3S4 compound and its preparation method provided by the present invention will be described in more detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0076] Example 1

[0077] Step 1: Weigh the required sulfur powder and nickel powder as reaction materials. The molar ratio of sulfur powder to nickel powder is 1.6:1, the particle size of both sulfur powder and nickel powder is 300μm, and the purity of both sulfur powder and nickel powder is ≥99%.

[0078] Step 2: Ball milling: Place the reaction raw materials from Step 1 into a ball mill jar, evacuate the ball mill jar and fill it with argon gas, and then place the ball mill jar containing the reaction raw materials into a ball mill to ball mill into a mixed powder of sulfur powder and nickel powder; the ball milling time is 50 hours.

[0079] Step 3: Acetone cleaning treatment: Put the mixed powder from step 2 into a beaker and add acetone for the first stirring and cleaning; wherein, the temperature of the beaker for acetone cleaning is 50℃, and the first stirring and cleaning time is 60min, that is, the acetone cleaning time is 60min.

[0080] Step 4: Distilled water washing treatment: Place the mixed powder after acetone washing in step 3 into a container filled with distilled water for a second stirring and washing; the second stirring and washing time is 30 minutes, that is, the distilled water washing time is 30 minutes.

[0081] Step 5: Vacuum drying treatment: Place the mixed powder washed with distilled water in step 4 into a vacuum drying oven for vacuum drying treatment. Turn off the power to the vacuum drying oven and let the mixed powder cool to room temperature with the vacuum drying oven; the vacuum drying temperature is 150℃ and the vacuum drying time is 5 hours.

[0082] Step 6: Sintering treatment: Place the mixed powder cooled to room temperature in Step 5 into a crucible, and then place the crucible containing the mixed powder into a plasma-activated sintering furnace for plasma-activated sintering to obtain the Ni3S4 compound; wherein the sintering temperature is 1500℃, the sintering pressure is 30MPa, and the sintering vacuum degree is 10. -1 Pa, sintering time is 5 min.

[0083] Step 7: Cooling treatment: The Ni3S4 compound obtained in step 6 is cooled in a plasma-activated sintering furnace.

[0084] Referring to Table 2, corrosion tests were conducted on 09CrCuSb steel and the Ni3S4 compound bulk material obtained in Example 1. Specifically, the 09CrCuSb steel and the Ni3S4 compound obtained in Example 1 were placed in a tubular container filled with H2S and SO2, and the corrosion test was carried out at 800°C. The flow ratio of H2S to SO2 was 2:1. The corrosion test results showed that the volumetric corrosion of the Ni3S4 compound was 5.1 mm. 3 The volumetric corrosion rate of 09CrCuSb steel is 21.3 mm / h. 3 / h, the volumetric corrosion of Ni3S4 compounds is about 1 / 4 of that of 09CrCuSb steel.

[0085] Example 2

[0086] Step 1: Weigh the required sulfur powder and nickel powder as reaction materials. The molar ratio of sulfur powder to nickel powder is 1.2:1, the particle size of both sulfur powder and nickel powder is 200μm, and the purity of both sulfur powder and nickel powder is 99.9%.

[0087] Step 2: Ball milling: Place the reaction raw materials from Step 1 into a ball mill jar, evacuate the ball mill jar and fill it with argon gas, and then place the ball mill jar containing the reaction raw materials into a ball mill to ball mill into a mixed powder of sulfur powder and nickel powder; the ball milling time is 5 hours.

[0088] Step 3: Acetone cleaning treatment: Put the mixed powder from step 2 into a beaker and add acetone for the first stirring and cleaning; wherein, the temperature of the beaker for acetone cleaning is 30℃, and the first stirring and cleaning time is 10 minutes, that is, the acetone cleaning time is 10 minutes.

[0089] Step 4: Distilled water washing treatment: Place the mixed powder after acetone washing in step 3 into a container filled with distilled water for a second stirring and washing; wherein, the second stirring and washing time is 5 minutes, that is, the distilled water washing time is 5 minutes.

[0090] Step 5: Vacuum drying treatment: Place the mixed powder washed with distilled water in step 4 into a vacuum drying oven for vacuum drying treatment. Turn off the power to the vacuum drying oven and let the mixed powder cool to room temperature with the vacuum drying oven; the vacuum drying temperature is 120℃ and the vacuum drying time is 1 hour.

[0091] Step 6: Sintering treatment: Place the mixed powder cooled to room temperature in Step 5 into a crucible, and then place the crucible containing the mixed powder into a plasma-activated sintering furnace for plasma-activated sintering to obtain the Ni3S4 compound; wherein the sintering temperature is 900℃, the sintering pressure is 10MPa, and the sintering vacuum degree is 10 -1 Pa, sintering time is 10 min.

[0092] Step 7: Cooling treatment: The Ni3S4 compound in step 6 is cooled in a plasma-activated sintering furnace.

[0093] Referring to Table 2, corrosion tests were conducted on 09CrCuSb steel and the Ni3S4 compound bulk material obtained in Example 2. Specifically, the 09CrCuSb steel and the Ni3S4 compound obtained in Example 2 were placed in a tubular container filled with H2S and SO2, and the corrosion test was carried out at 800°C. The flow ratio of H2S to SO2 was 2:1. The corrosion test results showed that the volumetric corrosion of the Ni3S4 compound was 6.9 mm. 3 The volumetric corrosion rate of 09CrCuSb steel is 21.3 mm / h. 3 / h, the volumetric corrosion of Ni3S4 compounds is about 1 / 3 of that of 09CrCuSb steel.

[0094] Example 3

[0095] Step 1: Weigh the required sulfur powder and nickel powder as reaction materials. The molar ratio of sulfur powder to nickel powder is 1.3:1, the particle size of sulfur powder and nickel powder is ≤100μm, and the purity of sulfur powder and nickel powder is 99.9%.

[0096] Step 2: Ball milling: Place the reaction raw materials from Step 1 into a ball mill jar, evacuate the ball mill jar and fill it with argon gas, then place the ball mill jar containing the reaction raw materials into a ball mill and ball mill it into a mixed powder of sulfur powder and nickel powder; the ball milling time is 25 hours.

[0097] Step 3: Acetone cleaning treatment: Put the mixed powder from step 2 into a beaker and add acetone for the first stirring and cleaning; wherein, the temperature of the beaker for acetone cleaning is 40℃, and the first stirring and cleaning time is 30min, that is, the acetone cleaning time is 30min.

[0098] Step 4: Distilled water washing treatment: Place the mixed powder after acetone washing in step 3 into a container filled with distilled water for a second stirring and washing; the second stirring and washing time is 20 minutes, that is, the distilled water washing time is 20 minutes.

[0099] Step 5: Vacuum drying treatment: Place the mixed powder washed with distilled water in step 4 into a vacuum drying oven for vacuum drying treatment. Turn off the power to the vacuum drying oven and let the mixed powder cool to room temperature with the vacuum drying oven; the vacuum drying temperature is 130℃ and the vacuum drying time is 2.5h.

[0100] Step 6: Sintering treatment: Place the mixed powder cooled to room temperature in Step 5 into a crucible, and then place the crucible containing the mixed powder into a plasma-activated sintering furnace for plasma-activated sintering to obtain the Ni3S4 compound; wherein the sintering temperature is 1300℃, the sintering pressure is 20MPa, and the sintering vacuum degree is 10. -1 Pa, sintering time is 7 min.

[0101] Step 7: Cooling treatment: The Ni3S4 compound from step 6 is cooled in a plasma-activated sintering furnace.

[0102] Referring to Table 2, corrosion tests were conducted on 09CrCuSb steel and the Ni3S4 compound bulk material obtained in Example 3. Specifically, the 09CrCuSb steel and the Ni3S4 compound obtained in Example 3 were placed in a tubular container filled with H2S and SO2, and the corrosion test was carried out at 800°C. The flow ratio of H2S to SO2 was 2:1. The corrosion test results showed that the volumetric corrosion of the Ni3S4 compound was 7.2 mm. 3 The volumetric corrosion rate of 09CrCuSb steel is 21.3 mm / h. 3 / h, the volumetric corrosion of Ni3S4 compounds is about 1 / 3 of that of 09CrCuSb steel.

[0103] Table 1: Comparison of relevant parameters for the preparation methods of Ni3S4 compounds in each embodiment.

[0104] Relevant parameters Example 1 Example 2 Example 3 molar ratio of sulfur powder to nickel powder 1.6：1 1.2：1 1.3：1 Particle size of sulfur powder and nickel powder 300μm 200μm ≤100μm Purity of sulfur powder and nickel powder ≥99％ 99.9％ 99.9％ Ball grinding time 50h 5h 25h Temperature of the beaker cleaned with acetone 50℃ 30℃ 40℃ Acetone cleaning time 60min 10min 30min Distilled water rinsing time 30min 5min 20min Vacuum drying temperature 150℃ 120℃ 130℃ Vacuum drying time 5h 1h 2.5h sintering temperature 1500℃ 900℃ 1300℃ Sintering pressure 30MPa 10MPa 20MPa Vacuum degree of sintering <![CDATA[10 -1 Well]]> <![CDATA[10 -1 Well]]> <![CDATA[10 -1 Well]]> Sintering time 5min 10min 7min

[0105] Table 2: Comparison of volumetric corrosion of Ni3S4 compounds in each embodiment and 09CrCuSb steel in the comparative example.

[0106]

[0107] In summary, the preparation method of Ni3S4 compound provided in this embodiment of the invention is simple, and the resulting Ni3S4 compound is low in cost. Compared with the sulfuric acid dew point corrosion resistant 09CrCuSb steel used in the prior art, the volumetric corrosion of Ni3S4 compound is about 1 / 4 to 1 / 3 of that of 09CrCuSb steel, further improving its corrosion resistance. It is suitable for widespread use in equipment such as coal-fired boilers, oil-fired boilers, coolers, and evaporators, improving the corrosion resistance of equipment, extending the life of equipment and related components, reducing maintenance costs and time, and improving equipment production efficiency.

[0108] Finally, it should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0109] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to the embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a Ni3S4 compound, characterized in that, Including the following steps: Weigh out the required sulfur powder and nickel powder as reaction raw materials, wherein the molar ratio of sulfur powder to nickel powder is (1.2-1.6):1; Grinding: The reactants are ground into a mixture of sulfur powder and nickel powder in an inert gas atmosphere; Cleaning: The ground mixture is then cleaned. Drying: The mixed powder after cleaning is placed in a vacuum drying oven for vacuum drying. Sintering: The mixed powder after vacuum drying is placed in a sintering furnace for sintering to obtain Ni3S4 compound; The step of placing the vacuum-dried mixed powder into a sintering furnace for sintering includes: cooling the mixed powder to room temperature in a vacuum drying oven, placing it in a crucible, and placing the crucible containing the mixed powder into a plasma-activated sintering furnace for plasma-activated sintering. The process conditions for the plasma-activated sintering treatment are as follows: the sintering temperature is between 900℃ and 1500℃, the sintering pressure is between 10MPa and 30MPa, and the sintering vacuum degree is ≤10. -1 Pa, the sintering time is between 5 min and 10 min.

2. The method for preparing the Ni3S4 compound according to claim 1, characterized in that, The step of grinding the reactants into a mixed powder of sulfur powder and nickel powder under an inert gas atmosphere includes: The reactants are placed in a ball mill jar, the ball mill jar is evacuated and filled with inert gas; The ball mill jar containing the reaction raw materials is placed in a ball mill for ball milling.

3. The method for preparing the Ni3S4 compound according to claim 2, characterized in that, The ball milling time is 5h-50h.

4. The method for preparing the Ni3S4 compound according to claim 1, characterized in that, The step of cleaning the ground mixed powder includes: The mixed powder is placed in a container containing acetone or ethanol for a first stirring and cleaning process. The mixed powder is placed in a container filled with distilled water for a second stirring and washing process.

5. The method for preparing the Ni3S4 compound according to claim 4, characterized in that, The first stirring and cleaning time is between 10 min and 60 min, and the second stirring and cleaning time is between 5 min and 30 min.

6. The method for preparing the Ni3S4 compound according to claim 4, characterized in that, The temperature of the first stirring and cleaning process is between 30℃ and 50℃.

7. The method for preparing the Ni3S4 compound according to claim 1, characterized in that, The vacuum drying temperature is between 120℃ and 150℃, and the vacuum drying time is between 1 hour and 5 hours.

8. The method for preparing the Ni3S4 compound according to claim 1, characterized in that, The particle size of both the sulfur powder and the nickel powder is ≤300μm, and / or the purity of both the sulfur powder and the nickel powder is ≥99%.

9. The method for preparing the Ni3S4 compound according to any one of claims 1-8, characterized in that, After the step of sintering the mixed powder in a sintering furnace to obtain the Ni3S4 compound, the process further includes: cooling: cooling the Ni3S4 compound along with the sintering furnace.

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