Method for preparing high-purity ultrafine spherical silicon powder by combining chemical purification and physical forming

Abstract

The application relates to the technical field of silicon powder, in particular to a method for preparing high-purity superfine spherical silicon powder by combining chemical purification and physical forming, which comprises the following steps: step 1, preparing mineral powder from quartz minerals; step 2, adding the mineral powder and sodium hydroxide into a reaction kettle to generate liquid sodium silicate; step 3, adding hydrochloric acid solution into the filtrate generated in step 2 to generate silica precipitate; step 4, repeating steps 2 and 3; and step 5, spraying and cooling the silica powder to form balls to obtain high-purity superfine spherical silicon powder. The method for preparing high-purity superfine spherical silicon powder by combining chemical purification and physical forming has the advantages that the silica in the quartz minerals is dissolved by alkali to generate sodium silicate, the sodium silicate is reacted with hydrochloric acid to generate high-purity silica powder, and finally, the high-purity superfine spherical silicon powder is formed by melting, spraying and cooling, and has the advantages of uniform particle size, high purity and high spheroidization rate.

Description

Technical Field

[0001] This invention relates to the field of silicon micropowder technology, and in particular to a method for preparing high-purity ultrafine spherical silicon micropowder by combining chemical purification and physical molding. Background Technology

[0002] Ultrafine spherical silicon powder refers to an inorganic non-metallic powder material with spherical particles and silicon dioxide (SiO2) as its main component. Compared with natural angular silicon powder, spherical silicon powder has significant advantages such as good flowability, excellent dielectric properties, low coefficient of thermal expansion, high filling rate, and less wear on molds. It is widely used in functional fillers such as epoxy molding compounds (EMC) for large-scale integrated circuit packaging and copper clad laminates (CCL), and is an important basic material supporting the development of the microelectronics industry.

[0003] Currently, the preparation methods for spherical silicon micropowder are mainly divided into two categories: physical methods and chemical methods. Physical methods involve melting irregular powder particles through high-temperature heat treatment and shrinking them into spheres due to surface tension. This is the main technical route for achieving industrial mass production and mainly includes flame sphericalization, plasma methods, and high-temperature melt spraying methods.

[0004] The flame spheroidization method involves feeding pulverized quartz powder into a high-temperature flame above 1600℃, causing the particle surface to melt and naturally spheroidize under surface tension. The product is then collected after cooling. The plasma method utilizes the high-temperature environment generated by an electric arc plasma to melt and spheroidize powder particles. This method involves extremely high heating temperatures, which can vaporize some impurities during spheroidization, thus achieving a certain purification effect. Furthermore, the atmosphere can be controlled according to process requirements, resulting in less pollution. The high-temperature melt spraying method involves melting high-purity quartz raw materials into a liquid state at 2100–2500℃, then atomizing and cooling them to form spherical particles. Products obtained using this method achieve high spheroidization and amorphization rates, with smooth particle surfaces.

[0005] However, the purity of products obtained by physical methods is greatly affected by the purity of the raw materials themselves. To improve the purity of the final product, it is necessary to remove as many impurities as possible from the raw materials (quartz minerals). Existing impurity removal methods mainly involve acid immersion, which has a limited effect. Therefore, we propose a method combining chemical purification and physical molding to prepare high-purity ultrafine spherical silica powder to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for preparing high-purity ultrafine spherical silicon micropowder by combining chemical purification and physical molding.

[0007] A method for preparing high-purity ultrafine spherical silicon micropowder by combining chemical purification and physical shaping includes the following steps:

[0008] Step 1: First, clean the quartz mineral, manually remove impurities, and then grind it into mineral powder.

[0009] Step 2: Mix the mineral powder and sodium hydroxide solution and add them to the reaction vessel. Heat the mixture to 160-170℃ and react for 6-8 hours to produce liquid sodium silicate. Filter the mixture while it is hot and collect the filtrate and filter residue.

[0010] Step 3: Add hydrochloric acid solution to the filtrate generated in Step 2 to generate silica precipitate. After the reaction, filter and wash the precipitate, and dry the filter cake to obtain silica powder.

[0011] Step 4: Repeat steps 2 and 3 to prepare and collect silica powder;

[0012] Step 5: Melt the silica powder collected in Step 4 into a liquid at 2100-2200℃, and then spray and cool it into spheres to obtain high-purity ultrafine spherical silica powder.

[0013] Preferably, in step 3, the molar ratio of the solute in the hydrochloric acid solution to the sodium hydroxide in step 2 is (1.2-1.5):1, and the concentration of the hydrochloric acid solution is 1-3 mol / L.

[0014] Preferably, in step 3, the filtrate obtained from the filtration in step 3 is collected and set aside for later use.

[0015] Preferably, in step 2, the filter residue is soaked in hydrochloric acid solution, filtered after soaking, mixed with new mineral powder, and then mixed with sodium hydroxide solution and added to the reaction vessel to prepare liquid sodium silicate.

[0016] Preferably, when repeating step 2, the filter residue from step 2 is soaked in the filtrate obtained in step 3.

[0017] Preferably, in step 5, at the instant the molten quartz flows out, it is sprayed with high-pressure nitrogen gas. The high-speed airflow disperses the viscous melt into tiny mist-like droplets. After cooling, the droplets solidify to form high-purity ultrafine spherical silicon powder.

[0018] Preferably, in step 5, the pressure of the high-pressure nitrogen gas is 4-6 MPa.

[0019] Preferably, in step 1, the quartz mineral is ground to 50-500 mesh.

[0020] Preferably, in step 3, the mass ratio of mineral powder to sodium hydroxide is 1:(0.5-1), and the concentration of sodium hydroxide solution is 1-2 mol / L.

[0021] The beneficial effects of this invention are:

[0022] 1. The method for preparing high-purity ultrafine spherical silica powder proposed in this invention combines chemical purification and physical molding. First, the silica in quartz minerals is dissolved by alkali to generate sodium silicate. Then, sodium silicate reacts with hydrochloric acid to generate high-purity silica powder. Finally, the powder is melted and spray-cooled to form high-purity ultrafine spherical silica powder with uniform particle size, high purity, and high sphericity.

[0023] 2. The method for preparing high-purity ultrafine spherical silicon micropowder proposed in this invention combines chemical purification and physical molding. The unreacted mineral powder in step 2 is collected and soaked in hydrochloric acid to remove insoluble hydroxide impurities such as iron and magnesium from the mineral powder, which is beneficial to the subsequent reaction of the mineral powder and reduces the impurity content. Furthermore, the filtrate obtained from filtration in step 3 is used to soak the filter residue in step 2, which recycles the waste liquid, saves raw materials, and effectively reduces the amount of waste liquid discharged. Detailed Implementation

[0024] The present invention will be further explained below with reference to specific embodiments.

[0025] In Example 1, the method for preparing high-purity ultrafine spherical silicon micropowder by combining chemical purification and physical shaping includes the following steps:

[0026] Step 1: First, clean the quartz mineral, manually remove impurities, and then grind it into mineral powder.

[0027] Step 2: Mix the mineral powder and sodium hydroxide solution and add them to the reaction vessel. Heat the mixture to 160°C and react for 6 hours to produce liquid sodium silicate. Filter the mixture while it is hot and collect the filtrate and filter residue.

[0028] Step 3: Add hydrochloric acid solution to the filtrate generated in Step 2 to generate silica precipitate. After the reaction, filter and wash the precipitate, and dry the filter cake to obtain silica powder.

[0029] Step 4: Repeat steps 2 and 3 to prepare and collect silica powder;

[0030] Step 5: Melt the silica powder collected in Step 4 into a liquid at 2100℃, and then spray and cool it into spheres to obtain high-purity ultrafine spherical silica powder.

[0031] In step 3, the molar ratio of the solute in the hydrochloric acid solution to the sodium hydroxide in step 2 is 1.5:1, and the concentration of the hydrochloric acid solution is 1 mol / L.

[0032] In step 3, collect the filtrate obtained from the filtration in step 3 and set it aside for later use.

[0033] In step 2, the filter residue is soaked in hydrochloric acid solution. After soaking, it is filtered, and the filter residue is mixed with new mineral powder. Then, it is mixed with sodium hydroxide solution and added to the reaction vessel to prepare liquid sodium silicate.

[0034] When repeating step 2, use the filtrate obtained from filtering in step 3 to soak the filter residue from step 2.

[0035] In step 5, at the instant the molten quartz flows out, it is sprayed with high-pressure nitrogen gas. The high-speed airflow disperses the viscous melt into tiny mist-like droplets. After cooling, the droplets solidify to form high-purity ultrafine spherical silica powder.

[0036] In step 5, the pressure of the high-pressure nitrogen gas is 4 MPa.

[0037] In step 1, the quartz mineral is ground to 50-500 mesh.

[0038] In step 3, the mass ratio of mineral powder to sodium hydroxide is 1:0.5, and the concentration of sodium hydroxide solution is 1 mol / L.

[0039] In Example 2, the method for preparing high-purity ultrafine spherical silicon micropowder by combining chemical purification and physical shaping includes the following steps:

[0040] Step 1: First, clean the quartz mineral, manually remove impurities, and then grind it into mineral powder.

[0041] Step 2: Mix the mineral powder and sodium hydroxide solution and add them to the reaction vessel. Heat the mixture to 170°C and react for 8 hours to produce liquid sodium silicate. Filter the mixture while it is hot and collect the filtrate and filter residue.

[0042] Step 3: Add hydrochloric acid solution to the filtrate generated in Step 2 to generate silica precipitate. After the reaction, filter and wash the precipitate, and dry the filter cake to obtain silica powder.

[0043] Step 4: Repeat steps 2 and 3 to prepare and collect silica powder;

[0044] Step 5: Melt the silica powder collected in Step 4 into a liquid at 2200℃, and then spray and cool it into spheres to obtain high-purity ultrafine spherical silica powder.

[0045] In step 3, the molar ratio of the solute in the hydrochloric acid solution to the sodium hydroxide in step 2 is 1.2:1, and the concentration of the hydrochloric acid solution is 3 mol / L.

[0046] In step 3, collect the filtrate obtained from the filtration in step 3 and set it aside for later use.

[0047] In step 2, the filter residue is soaked in hydrochloric acid solution. After soaking, it is filtered, and the filter residue is mixed with new mineral powder. Then, it is mixed with sodium hydroxide solution and added to the reaction vessel to prepare liquid sodium silicate.

[0048] When repeating step 2, use the filtrate obtained from filtering in step 3 to soak the filter residue from step 2.

[0049] In step 5, at the instant the molten quartz flows out, it is sprayed with high-pressure nitrogen gas. The high-speed airflow disperses the viscous melt into tiny mist-like droplets. After cooling, the droplets solidify to form high-purity ultrafine spherical silica powder.

[0050] In step 5, the pressure of the high-pressure nitrogen gas is 4-6 MPa.

[0051] In step 1, the quartz mineral is ground to 50-500 mesh.

[0052] In step 3, the mass ratio of mineral powder to sodium hydroxide is 1:0.8, and the concentration of sodium hydroxide solution is 1.5 mol / L.

[0053] In Example 3, the method for preparing high-purity ultrafine spherical silicon micropowder by combining chemical purification and physical shaping includes the following steps:

[0054] Step 1: First, clean the quartz mineral, manually remove impurities, and then grind it into mineral powder.

[0055] Step 2: Mix the mineral powder and sodium hydroxide solution and add them to the reaction vessel. Heat the mixture to 165°C and react for 7 hours to produce liquid sodium silicate. Filter the mixture while it is hot and collect the filtrate and filter residue.

[0056] Step 3: Add hydrochloric acid solution to the filtrate generated in Step 2 to generate silica precipitate. After the reaction, filter and wash the precipitate, and dry the filter cake to obtain silica powder.

[0057] Step 4: Repeat steps 2 and 3 to prepare and collect silica powder;

[0058] Step 5: Melt the silica powder collected in Step 4 into a liquid at 2150℃, and then spray and cool it into spheres to obtain high-purity ultrafine spherical silica powder.

[0059] In step 3, the molar ratio of the solute in the hydrochloric acid solution to the sodium hydroxide in step 2 is 1.3:1, and the concentration of the hydrochloric acid solution is 2 mol / L.

[0060] In step 3, collect the filtrate obtained from the filtration in step 3 and set it aside for later use.

[0061] In step 2, the filter residue is soaked in hydrochloric acid solution. After soaking, it is filtered, and the filter residue is mixed with new mineral powder. Then, it is mixed with sodium hydroxide solution and added to the reaction vessel to prepare liquid sodium silicate.

[0062] When repeating step 2, use the filtrate obtained from filtering in step 3 to soak the filter residue from step 2.

[0063] In step 5, at the instant the molten quartz flows out, it is sprayed with high-pressure nitrogen gas. The high-speed airflow disperses the viscous melt into tiny mist-like droplets. After cooling, the droplets solidify to form high-purity ultrafine spherical silica powder.

[0064] In step 5, the pressure of the high-pressure nitrogen gas is 5 MPa.

[0065] In step 1, the quartz mineral is ground to 50-500 mesh.

[0066] In step 3, the mass ratio of mineral powder to sodium hydroxide is 1:0.7, and the concentration of sodium hydroxide solution is 1.5 mol / L.

[0067] In Example 4, the method for preparing high-purity ultrafine spherical silicon micropowder by combining chemical purification and physical shaping includes the following steps:

[0068] Step 1: First, clean the quartz mineral, manually remove impurities, and then grind it into mineral powder.

[0069] Step 2: Mix the mineral powder and sodium hydroxide solution and add them to the reaction vessel. Heat the mixture to 160°C and react for 6 hours to produce liquid sodium silicate. Filter the mixture while it is hot and collect the filtrate and filter residue.

[0070] Step 3: Add hydrochloric acid solution to the filtrate generated in Step 2 to generate silica precipitate. After the reaction, filter and wash the precipitate, and dry the filter cake to obtain silica powder.

[0071] Step 4: Repeat steps 2 and 3 to prepare and collect silica powder;

[0072] Step 5: Melt the silica powder collected in Step 4 into a liquid at 2100℃, and then spray and cool it into spheres to obtain high-purity ultrafine spherical silica powder.

[0073] In step 3, the molar ratio of the solute in the hydrochloric acid solution to the sodium hydroxide in step 2 is 1.3:1, and the concentration of the hydrochloric acid solution is 2 mol / L.

[0074] In step 3, collect the filtrate obtained from the filtration in step 3 and set it aside for later use.

[0075] In step 2, the filter residue is soaked in hydrochloric acid solution. After soaking, it is filtered, and the filter residue is mixed with new mineral powder. Then, it is mixed with sodium hydroxide solution and added to the reaction vessel to prepare liquid sodium silicate.

[0076] When repeating step 2, use the filtrate obtained from filtering in step 3 to soak the filter residue from step 2.

[0077] In step 5, at the instant the molten quartz flows out, it is sprayed with high-pressure nitrogen gas. The high-speed airflow disperses the viscous melt into tiny mist-like droplets. After cooling, the droplets solidify to form high-purity ultrafine spherical silica powder.

[0078] In step 5, the pressure of the high-pressure nitrogen gas is 5 MPa.

[0079] In step 1, the quartz mineral is ground to 50-500 mesh.

[0080] In step 3, the mass ratio of mineral powder to sodium hydroxide is 1:0.7, and the concentration of sodium hydroxide solution is 1.5 mol / L.

[0081] In Example 5, the method for preparing high-purity ultrafine spherical silicon powder by combining chemical purification and physical shaping includes the following steps:

[0082] Step 1: First, clean the quartz mineral, manually remove impurities, and then grind it into mineral powder.

[0083] Step 2: Mix the mineral powder and sodium hydroxide solution and add them to the reaction vessel. Heat the mixture to 170°C and react for 8 hours to produce liquid sodium silicate. Filter the mixture while it is hot and collect the filtrate and filter residue.

[0084] Step 3: Add hydrochloric acid solution to the filtrate generated in Step 2 to generate silica precipitate. After the reaction, filter and wash the precipitate, and dry the filter cake to obtain silica powder.

[0085] Step 4: Repeat steps 2 and 3 to prepare and collect silica powder;

[0086] Step 5: Melt the silica powder collected in Step 4 into a liquid at 2200℃, and then spray and cool it into spheres to obtain high-purity ultrafine spherical silica powder.

[0087] In step 3, the molar ratio of the solute in the hydrochloric acid solution to the sodium hydroxide in step 2 is 1.3:1, and the concentration of the hydrochloric acid solution is 2 mol / L.

[0088] In step 3, collect the filtrate obtained from the filtration in step 3 and set it aside for later use.

[0089] In step 2, the filter residue is soaked in hydrochloric acid solution. After soaking, it is filtered, and the filter residue is mixed with new mineral powder. Then, it is mixed with sodium hydroxide solution and added to the reaction vessel to prepare liquid sodium silicate.

[0090] When repeating step 2, use the filtrate obtained from filtering in step 3 to soak the filter residue from step 2.

[0091] In step 5, at the instant the molten quartz flows out, it is sprayed with high-pressure nitrogen gas. The high-speed airflow disperses the viscous melt into tiny mist-like droplets. After cooling, the droplets solidify to form high-purity ultrafine spherical silica powder.

[0092] In step 5, the pressure of the high-pressure nitrogen gas is 5 MPa.

[0093] In step 1, the quartz mineral is ground to 50-500 mesh.

[0094] In step 3, the mass ratio of mineral powder to sodium hydroxide is 1:0.7, and the concentration of sodium hydroxide solution is 1.5 mol / L.

[0095] The silicon micropowders prepared in Examples 1-5 were subjected to physical property tests, and the results are listed in Table 1. The tests included purity, sphericity, and particle size.

[0096]

[0097] As can be seen from Examples 1-5, the silicon micropowder prepared by this method has high purity and sphericity, and an average particle size of less than 7 μm.

[0098] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing high-purity ultrafine spherical silica powder by combining chemical purification and physical molding, characterized in that, Includes the following steps: Step 1: First, clean the quartz mineral, manually remove impurities, and then grind it into mineral powder. Step 2: Mix the mineral powder and sodium hydroxide solution and add them to the reaction vessel. Heat the mixture to 160-170℃ and react for 6-8 hours to produce liquid sodium silicate. Filter the mixture while it is hot and collect the filtrate and filter residue. Step 3: Add hydrochloric acid solution to the filtrate generated in Step 2 to generate silica precipitate. After the reaction, filter and wash the precipitate, and dry the filter cake to obtain silica powder. Step 4: Repeat steps 2 and 3 to prepare and collect silica powder; Step 5: Melt the silica powder collected in Step 4 into a liquid at 2100-2200℃, and then spray and cool it into spheres to obtain high-purity ultrafine spherical silica powder.

2. The method for preparing high-purity ultrafine spherical silicon micropowder by combining chemical purification and physical molding according to claim 1, characterized in that, In step 3, the molar ratio of the solute in the hydrochloric acid solution to the sodium hydroxide in step 2 is (1.2-1.5):1, and the concentration of the hydrochloric acid solution is 1-3 mol / L.

3. The method for preparing high-purity ultrafine spherical silicon micropowder by combining chemical purification and physical molding according to claim 1, characterized in that, In step 3, the filtrate obtained from the filtration in step 3 is collected and set aside for later use.

4. The method for preparing high-purity ultrafine spherical silicon micropowder by combining chemical purification and physical shaping according to claim 3, characterized in that, In step 2, the filter residue is soaked in hydrochloric acid solution. After soaking, it is filtered. The filter residue is mixed with new mineral powder, and then mixed with sodium hydroxide solution and added to the reaction vessel to prepare liquid sodium silicate.

5. The method for preparing high-purity ultrafine spherical silicon micropowder by combining chemical purification and physical shaping according to claim 4, characterized in that, When repeating step 2, use the filtrate obtained from filtering in step 3 to soak the filter residue from step 2.

6. The method for preparing high-purity ultrafine spherical silica powder by combining chemical purification and physical shaping according to claim 1, characterized in that, In step 5, at the instant the molten quartz flows out, it is sprayed with high-pressure nitrogen gas. The high-speed airflow disperses the viscous melt into tiny mist-like droplets. After cooling, the droplets solidify to form high-purity ultrafine spherical silicon powder.

7. The method for preparing high-purity ultrafine spherical silicon micropowder by combining chemical purification and physical shaping according to claim 6, characterized in that, In step 5, the pressure of the high-pressure nitrogen gas is 4-6 MPa.

8. The method for preparing high-purity ultrafine spherical silicon micropowder by combining chemical purification and physical shaping according to claim 1, characterized in that, In step 1, the quartz mineral is ground to 50-500 mesh.

9. The method for preparing high-purity ultrafine spherical silicon micropowder by combining chemical purification and physical shaping according to claim 1, characterized in that, In step 3, the mass ratio of mineral powder to sodium hydroxide is 1:(0.5-1), and the concentration of sodium hydroxide solution is 1-2 mol / L.

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