Preparation method of superfine magnesium oxide powder

Abstract

The invention discloses a preparation method of superfine magnesium oxide powder. The preparation method comprises the following steps: preparing magnesium oxide granulation powder; vaporizing the magnesium oxide granulation powder and quickly condensing to obtain spherical magnesium oxide powder; and sorting the spherical magnesium oxide powder to obtain the high-purity superfine magnesium oxide powder. According to the preparation method of the superfine magnesium oxide powder, the superfine magnesium oxide powder can be prepared, and the powder is spherical and has good dispersity.

Description

Technical Field

[0001] The invention belongs to the technical field of material science, and in particular provides a method for preparing ultrafine magnesium oxide powder. Background Art

[0002] Magnesium oxide is an excellent filler and reinforcing agent for rubber products, which can improve the quality and strength of rubber products. It can also be used to manufacture advanced glass products, adhesives, paints and daily chemicals. Ultrafine magnesium oxide has the characteristics of light weight and good activity. It can be used as a filler for paper, an accelerator and activator for chlororubber and fluororubber, and has important use value in many industries. However, for a long time, the preparation technology of high-purity ultrafine magnesium oxide powder (below 100nm) has been difficult to break through. Therefore, it has become an urgent problem to propose a method for preparing ultrafine magnesium oxide powder. Summary of the invention

[0003] In view of this, the object of the present invention is to provide a method for preparing ultrafine magnesium oxide powder, using high-purity magnesium oxide as a raw material and utilizing the property of magnesium oxide that is easily vaporized at high temperatures to prepare a high-purity ultrafine magnesium oxide product.

[0004] The present invention provides a method for preparing ultrafine magnesium oxide powder, comprising:

[0005] Step 1: Preparation of magnesium oxide granulated powder

[0006] A spray granulation slurry is prepared using magnesium oxide powder as a raw material, polyvinyl butyral as a binder, and ethanol as a solvent, and the spray granulation slurry is granulated to obtain magnesium oxide granulated powder;

[0007] Step 2: Vaporize the magnesium oxide granulated powder and rapidly condense it to obtain spherical magnesium oxide powder

[0008] (1) Obtain a stable plasma torch;

[0009] (2) vaporizing the magnesium oxide granulated powder by using the plasma torch in a central powder feeding manner to obtain magnesium oxide vapor;

[0010] (3) rapidly condensing the magnesium oxide vapor to obtain spherical magnesium oxide powder;

[0011] Step 3: sorting the spherical magnesium oxide powder to separate the coarse particle powder product to obtain high-purity ultrafine magnesium oxide powder.

[0012] Preferably, in step 1, the weight of the polyvinyl butyral is 1%-5% of the weight of the magnesium oxide powder.

[0013] More preferably, in step 1, the magnesium oxide powder is light magnesium oxide powder.

[0014] More preferably, in step 1, the granulation process adopts a centrifugal spray granulation process.

[0015] More preferably, in step 1, the granulation particle size is below 40 μm.

[0016] Further preferably, in step 2, a high-frequency plasma device is used to obtain a stable high-temperature plasma torch, wherein the flame temperature of the high-temperature plasma torch is above 7000K.

[0017] Further preferably, in step 2, powder is delivered to the center of the flame of the plasma torch by central powder delivery, wherein the vaporization temperature of the powder is controlled at 8000-9500K, nitrogen or air is used as the powder delivery gas, and the powder delivery rate is controlled at 80-150g / min.

[0018] Further preferably, in step 2, the method for rapidly condensing the magnesium oxide vapor is as follows: dry compressed air is introduced into the periphery of the magnesium oxide vapor to rapidly condense the magnesium oxide vapor, wherein the compressed air temperature is -25°C-40°C and the flow rate is 500-1200 L / min.

[0019] Further preferably, in step 3, an induced draft fan is used to introduce the spherical magnesium oxide powder into a powder collection system along with a compressed air flow, wherein the powder collection system consists of a cyclone separator, a bag collector and an electrostatic precipitator, the cyclone separator is used to remove a small amount of large particle impurities, the bag collector is used to collect the remaining powder after impurities are removed by the cyclone separator, and the electrostatic precipitator is used to further capture the remaining powder in the flue gas.

[0020] The beneficial effects of the method for preparing ultrafine magnesium oxide powder provided by the present invention are as follows:

[0021] 1. This method solves the problem of difficulty in preparing ultrafine (below 100nm) magnesium oxide

[0022] Generally speaking, ultrafine ceramic powders are usually prepared by grinding or chemical synthesis to obtain ultrafine powders, but the current grinding methods cannot grind powder products below 100nm, and the products synthesized by chemical methods must undergo a sintering process in the later stage, during which agglomeration and particle growth are prone to occur, resulting in a decrease in product quality. This method uses a purely physical method to directly condense magnesium oxide in a gaseous state to obtain ultrafine powders, effectively avoiding powder agglomeration, and under the condition of controlling the degree of supercooling and air flow velocity, it is difficult for particles to grow, thereby obtaining high-quality ultrafine powders;

[0023] 2. This method can improve the purity of raw materials

[0024] The plasma flame has a very high temperature. At this temperature, some low-melting-point components will be evaporated first. Therefore, the powder product of this scheme has a certain room for improvement in purity compared to the raw material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments:

[0026] Figure 1 This is a microscopic schematic diagram of the ultrafine magnesium oxide powder prepared in Example 1;

[0027] Figure 2 This is a microscopic schematic diagram of the ultrafine magnesium oxide powder obtained in Example 2;

[0028] Figure 3 This is a microscopic schematic diagram of the ultrafine magnesium oxide powder prepared in Example 3. DETAILED DESCRIPTION

[0029] The present invention will be further explained below in conjunction with specific implementation schemes, but the present invention is not limited thereto.

[0030] The present invention provides a method for preparing ultrafine magnesium oxide powder, which is characterized by comprising:

[0031] Step 1: Preparation of magnesium oxide granulated powder

[0032] A spray granulation slurry is prepared using magnesium oxide powder as a raw material, polyvinyl butyral (PVB) as a binder, and ethanol as a solvent, and the spray granulation slurry is granulated to obtain magnesium oxide granulated powder, wherein the weight of the polyvinyl butyral (PVB) is 1%-5% of the weight of the magnesium oxide powder;

[0033] The magnesium oxide powder is a light magnesium oxide powder; the granulation process adopts a centrifugal spray granulation process; the granulation particle size is less than 40 μm;

[0034] Step 2: Vaporize the magnesium oxide granulated powder and rapidly condense it to obtain spherical magnesium oxide powder

[0035] (1) Obtain a stable plasma torch

[0036] Use high-frequency plasma equipment to obtain a stable high-temperature plasma torch. Specifically, increase the voltage to 7000V, introduce argon gas for ignition, and continue to increase the voltage to 9500V-10500V after ignition. At the same time, introduce air to a flow rate of 60-80L / min, and adjust the equipment frequency to between 2.6-2.8MHz. At this time, a suitable flame (temperature above 7000K) can be obtained;

[0037] (2) using the plasma torch to vaporize the magnesium oxide granulated powder in a central powder feeding manner to obtain magnesium oxide vapor

[0038] The powder is fed to the center of the flame of the plasma torch by a central powder feeding method, wherein the vaporization temperature of the powder is adjusted by controlling the vertical position of the powder feeding nozzle, and the vaporization temperature is controlled at 8000-9500K; nitrogen or air is used as the powder feeding gas for powder feeding, and the powder feeding rate is controlled at 80-150g / min;

[0039] (3) Rapidly condensing the magnesium oxide vapor to obtain spherical magnesium oxide powder

[0040] Dry compressed air is introduced into the periphery of the magnesium oxide steam to quickly condense the magnesium oxide steam to obtain spherical magnesium oxide powder, wherein the compressed air temperature is -25°C-40°C and the flow rate is 500-1200L / min;

[0041] Step 3: Sorting the spherical magnesium oxide powder to separate the coarse particle powder product to obtain high-purity ultrafine magnesium oxide powder

[0042] The spherical magnesium oxide powder is introduced into a powder collection system along with a compressed air flow by an induced draft fan, wherein the powder collection system consists of a cyclone separator, a bag collector and an electrostatic precipitator. The cyclone separator is used to remove a small amount of large particle impurities, the bag collector is used to collect the remaining powder after the cyclone separator removes impurities, and the electrostatic precipitator is used to further capture the remaining powder in the flue gas.

[0043] The method for preparing ultrafine magnesium oxide powder comprises: preparing magnesium oxide granulated powder; sending the prefabricated magnesium oxide granulated powder into the center of a high-temperature plasma flame, utilizing high temperature to instantly vaporize the powder to form magnesium oxide steam, utilizing low-temperature gases such as compressed air or liquid nitrogen to rapidly condense the steam to obtain ultrafine nano magnesium oxide powder, and finally sorting the magnesium oxide powder to obtain high-purity ultrafine nano magnesium oxide powder, wherein the ultrafine nano magnesium oxide powder obtained after intense vaporization and rapid condensation has a particle size of less than 100 nm, is spherical, and has good dispersibility.

[0044] Example 1

[0045] Preparation of ultrafine magnesium oxide powder, the steps are as follows:

[0046] Step 1: Preparation of magnesium oxide granulated powder

[0047] According to the weight ratio: 100 parts of light magnesium oxide powder, 2 parts of polyvinyl butyral (PVB), and 45 parts of ethanol are prepared into a spray granulation slurry and centrifugal spray granulation is performed to obtain magnesium oxide granulation powder, wherein the granulation particle size is less than 40 μm;

[0048] Step 2: Vaporize the magnesium oxide granulated powder and rapidly condense it to obtain spherical magnesium oxide powder

[0049] (1) Obtain a stable plasma torch

[0050] A high-frequency plasma device is used to obtain a stable high-temperature plasma torch. Specifically, the voltage is increased to 7000V, argon gas is introduced for ignition, and the voltage is continuously increased to 9500V after ignition. At the same time, air is introduced to a flow rate of 70L / min, and the device frequency is adjusted to between 2.6MHz. At this time, a stable plasma flame (temperature above 7000K) is obtained;

[0051] (2) using the plasma torch to vaporize the magnesium oxide granulated powder in a central powder feeding manner to obtain magnesium oxide vapor

[0052] The powder is fed to the center of the flame of the plasma torch by a central powder feeding method, wherein the vaporization temperature of the powder is controlled at 9000K; air is used as the powder feeding gas during powder feeding, and the powder feeding rate is controlled at 100g / min;

[0053] (3) Rapidly condensing the magnesium oxide vapor to obtain spherical magnesium oxide powder

[0054] Dry compressed air is introduced into the periphery of the magnesium oxide vapor to rapidly condense the magnesium oxide vapor to obtain spherical magnesium oxide powder, wherein the compressed air temperature is -25°C and the flow rate is 850L / min;

[0055] Step 3: Sorting the spherical magnesium oxide powder to separate the coarse particle powder product to obtain high-purity ultrafine magnesium oxide powder

[0056] The spherical magnesium oxide powder is introduced into a powder collection system along with a compressed air flow by an induced draft fan, wherein the powder collection system consists of a cyclone separator, a bag collector and an electrostatic precipitator. The cyclone separator is used to remove a small amount of large particle impurities, the bag collector is used to collect the remaining powder after the cyclone separator removes impurities, and the electrostatic precipitator is used to further capture the remaining powder in the flue gas.

[0057] The high-purity ultrafine magnesium oxide powder finally obtained is Figure 1 shown.

[0058] Example 2

[0059] Preparation of ultrafine magnesium oxide powder, the steps are as follows:

[0060] Step 1: Preparation of magnesium oxide granulated powder

[0061] According to the weight ratio: 100 parts of light magnesium oxide powder, 1 part of polyvinyl butyral (PVB), and 45 parts of ethanol are prepared into a spray granulation slurry and centrifugal spray granulation is performed to obtain magnesium oxide granulation powder, wherein the granulation particle size is less than 40 μm;

[0062] Step 2: Vaporize the magnesium oxide granulated powder and rapidly condense it to obtain spherical magnesium oxide powder

[0063] (1) Obtain a stable plasma torch

[0064] A high-frequency plasma device is used to obtain a stable high-temperature plasma torch. Specifically, the voltage is increased to 7000V, argon gas is introduced for ignition, and the voltage is continuously increased to 10500V after ignition. At the same time, air is introduced to a flow rate of 60L / min, and the device frequency is adjusted to between 2.7MHz. At this time, a stable plasma flame (temperature above 7000K) is obtained;

[0065] (2) using the plasma torch to vaporize the magnesium oxide granulated powder in a central powder feeding manner to obtain magnesium oxide vapor

[0066] The powder is fed to the center of the flame of the plasma torch by a central powder feeding method, wherein the vaporization temperature of the powder is controlled at 9500K; air is used as the powder feeding gas during powder feeding, and the powder feeding rate is controlled at 150g / min;

[0067] (3) Rapidly condensing the magnesium oxide vapor to obtain spherical magnesium oxide powder

[0068] Dry compressed air is introduced into the periphery of the magnesium oxide vapor to quickly condense the magnesium oxide vapor, wherein the compressed air temperature is -10°C and the flow rate is 500L / min;

[0069] Step 3: Sorting the spherical magnesium oxide powder to separate the coarse particle powder product to obtain high-purity ultrafine magnesium oxide powder

[0070] The spherical magnesium oxide powder is introduced into a powder collection system along with a compressed air flow by an induced draft fan, wherein the powder collection system consists of a cyclone separator, a bag collector and an electrostatic precipitator. The cyclone separator is used to remove a small amount of large particle impurities, the bag collector is used to collect the remaining powder after the cyclone separator removes impurities, and the electrostatic precipitator is used to further capture the remaining powder in the flue gas.

[0071] The high-purity ultrafine magnesium oxide powder finally obtained is Figure 2 shown.

[0072] Example 3

[0073] Preparation of ultrafine magnesium oxide powder, the steps are as follows:

[0074] Step 1: Preparation of magnesium oxide granulated powder

[0075] According to the weight ratio: 100 parts of light magnesium oxide powder, 5 parts of polyvinyl butyral (PVB), and 45 parts of ethanol are prepared into a spray granulation slurry and centrifugal spray granulation is performed to obtain magnesium oxide granulation powder, wherein the granulation particle size is less than 40 μm;

[0076] Step 2: Vaporize the magnesium oxide granulated powder and rapidly condense it to obtain spherical magnesium oxide powder

[0077] (1) Obtain a stable plasma torch

[0078] A stable high-temperature plasma torch was obtained by using a high-frequency plasma device. Specifically, the voltage was increased to 7000V, argon gas was introduced for ignition, and the voltage was continuously increased to 10000V after ignition. At the same time, air was introduced to a flow rate of 80L / min, and the device frequency was adjusted to between 2.8MHz. At this time, a stable plasma flame (temperature above 7000K) was obtained.

[0079] (2) using the plasma torch to vaporize the magnesium oxide granulated powder in a central powder feeding manner to obtain magnesium oxide vapor

[0080] The powder is fed to the center of the flame of the plasma torch by a central powder feeding method, wherein the vaporization temperature of the powder is controlled at 8000K; nitrogen is used as the powder feeding gas during powder feeding, and the powder feeding rate is controlled at 80g / min;

[0081] (3) Rapidly condensing the magnesium oxide vapor to obtain spherical magnesium oxide powder

[0082] Dry compressed air is introduced into the periphery of the magnesium oxide vapor to rapidly condense the magnesium oxide vapor to obtain spherical magnesium oxide powder, wherein the compressed air temperature is 40° C. and the flow rate is 1200 L / min;

[0083] Step 3: Sorting the spherical magnesium oxide powder to separate the coarse particle powder product to obtain high-purity ultrafine magnesium oxide powder

[0084] The spherical magnesium oxide powder is introduced into a powder collection system along with a compressed air flow by an induced draft fan, wherein the powder collection system consists of a cyclone separator, a bag collector and an electrostatic precipitator. The cyclone separator is used to remove a small amount of large particle impurities, the bag collector is used to collect the remaining powder after the cyclone separator removes impurities, and the electrostatic precipitator is used to further capture the remaining powder in the flue gas.

[0085] The high-purity ultrafine magnesium oxide powder finally obtained is Figure 3 shown.

[0086] pass Figures 1 to 3 It can be seen that the obtained powder products have a particle size of less than 100 nm and are spherical, indicating that the expected powder products can be obtained according to the technical method of the present invention.

[0087] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for preparing ultrafine magnesium oxide powder, characterized in that: include: Step 1: Preparation of magnesium oxide granulated powder A spray granulation slurry is prepared using magnesium oxide powder as a raw material, polyvinyl butyral as a binder, and ethanol as a solvent, and the spray granulation slurry is granulated to obtain magnesium oxide granulated powder; Step 2: Vaporize the magnesium oxide granulated powder and rapidly condense it to obtain ultrafine spherical magnesium oxide powder (1) Obtain a stable plasma torch; (2) using the plasma torch to vaporize the magnesium oxide granulated powder in a central powder feeding manner to obtain magnesium oxide vapor; (3) rapidly condensing the magnesium oxide vapor to obtain spherical magnesium oxide powder; Step 3: sorting the spherical magnesium oxide powder to separate the coarse particle powder product to obtain high-purity ultrafine magnesium oxide powder.

2. The method for preparing ultrafine magnesium oxide powder according to claim 1, characterized in that: In step 1, the weight of the polyvinyl butyral is 1%-5% of the weight of the magnesium oxide powder.

3. The method for preparing ultrafine magnesium oxide powder according to claim 1, characterized in that: In step 1, the magnesium oxide powder is light magnesium oxide powder.

4. The method for preparing ultrafine magnesium oxide powder according to claim 1, characterized in that: In step 1, the granulation process adopts a centrifugal spray granulation process.

5. The method for preparing ultrafine magnesium oxide powder according to claim 1, characterized in that: In step 1, the granulation particle size is below 40 μm.

6. The method for preparing ultrafine magnesium oxide powder according to claim 1, characterized in that: In step 2, a high-frequency plasma device is used to obtain a stable high-temperature plasma torch, wherein the flame temperature of the high-temperature plasma torch is above 7000K.

7. The method for preparing ultrafine magnesium oxide powder according to claim 1, characterized in that: In step 2, powder is delivered to the center of the flame of the plasma torch by central powder delivery, wherein the vaporization temperature of the powder is controlled at 8000-9500K, nitrogen or air is used as the powder delivery gas, and the powder delivery rate is controlled at 80-150g / min.

8. The method for preparing ultrafine magnesium oxide powder according to claim 1, characterized in that: In step 2, the method for rapidly condensing the magnesium oxide vapor is as follows: dry compressed air is introduced into the periphery of the magnesium oxide vapor to rapidly condense the magnesium oxide vapor, wherein the compressed air temperature is -25°C-40°C and the flow rate is 500-1200 L / min.

9. The method for preparing ultrafine magnesium oxide powder according to claim 1, characterized in that: In step 3, the spherical magnesium oxide powder is introduced into a powder collection system along with a compressed air flow by an induced draft fan, wherein the powder collection system consists of a cyclone separator, a bag collector and an electrostatic precipitator, the cyclone separator is used to remove a small amount of large particle impurities, the bag collector is used to collect the remaining powder after the cyclone separator removes impurities, and the electrostatic precipitator is used to further capture the remaining powder in the flue gas.

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