CN112374504A - Process for manufacturing nano silicon dioxide by physical method - Google Patents
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- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
- C01B33/187—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by acidic treatment of silicates
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Abstract
The invention discloses a process for preparing nano silicon dioxide by a physical method, which comprises the steps of raw material pretreatment, raw material particle surface treatment, primary crushing, particle dispersion, secondary crushing, particle dispersion and homogenization. The crystalline state and the granularity of a product prepared by the process for manufacturing the nano silicon dioxide by the physical method can not be achieved by the prior process; on the basis that the product purity reaches more than 99.9 percent, the process can meet the requirements of different industries such as chemical industry, electronics, integrated circuit wafers, LED substrate materials CMP and the like, and presents physical and chemical characteristics different from products manufactured by a non-physical manufacturing process; the solid content of the aqueous slurry of the product prepared by the invention can reach 50.5%, and the dispersion time at normal temperature is more than 180 days. Compared with the existing products with the same purity in the market, the process cost of the invention is less than 50%, the process of the invention has no dangerous raw materials such as inflammable, explosive, toxic, strong acid, strong alkali and the like, and has no high-temperature and high-pressure process.
Description
Technical Field
The invention relates to the technical field of silicon dioxide production processes, in particular to a process for manufacturing nano silicon dioxide by a physical method.
Background
The existing nano silicon dioxide is prepared by a chemical method, and the preparation method comprises a gas phase method, a precipitation method, a kaolin or hard kaolin silicon source method and a coal gangue or fly ash silicon source method.
The vapor phase processes are mainly Chemical Vapor Deposition (CVD) processes, also known as pyrolysis, dry or combustion processes. The raw materials are silicon tetrachloride, oxygen (or air) and hydrogen which are reacted at high temperature. The reaction formula is as follows:
SiCl4+ 2H2+ O2—>SiO2+4HCl
air and hydrogen are respectively pressurized, separated, cooled and dehydrated, dried by silica gel, dedusted and filtered, and then are sent into a synthetic hydrolysis furnace. The silicon tetrachloride raw material is sent to a rectifying tower for rectification, then is heated and evaporated in an evaporator, and is sent to a synthetic hydrolysis furnace by taking dried and filtered air as a carrier. After the silicon tetrachloride is gasified at high temperature (flame temperature is 1000-1800 ℃), carrying out gas phase hydrolysis on the silicon tetrachloride and a certain amount of hydrogen and oxygen (or air) at the high temperature of about 1800 ℃; at the moment, the generated fumed silica particles are extremely fine and form aerosol with gas, so that the aerosol is not easy to trap, and the fumed silica particles are firstly gathered into larger particles in a collector, then the larger particles are collected by a cyclone separator, and then the larger particles are sent into a deacidification furnace, and the fumed silica is blown by nitrogen-containing air until the pH value is 4-6, so that a finished product is obtained.
The precipitation method is also called sodium silicate acidification method, and water glass solution is adopted to react with acid, and the nano silicon dioxide is obtained through precipitation, filtration, washing, drying and calcination. The reaction formula is as follows:
Na2SiO3 + 2H+ —> SiO2+ 2Na+ + H2O
the kaolin or hard kaolin silicon source method comprises the following steps: firstly, crushing kaolin or hard kaolin to 50-60 meshes, then roasting for 2 hours at a high temperature of 500-600 ℃, and then mixing roasted soil with 30% industrial hydrochloric acid according to the weight ratio of 1: 2.5 (weight) burdening, carrying out acid leaching for 7 hours at about 90 ℃, and neutralizing, filtering, washing and drying to obtain nano silicon dioxide, wherein the product quality meets the GB10507-89 standard; and simultaneously obtaining the high-efficiency water purifying agent polyaluminium chloride. The roasting and acid leaching reaction formula is as follows:
roasting: al (Al)2O3•2SiO2•2H2O —> Al2O3•2SiO2 + 2H2O
Acid leaching: al (Al)2O3•2SiO2 + 6HCl + 9H2O—>2AlCl3•6H2O + 2SiO2
The method for preparing the silicon source of the coal gangue or the fly ash comprises the following steps: firstly, coal gangue or fly ash is crushed to the granularity of less than 120 meshes, and then the method comprises two steps:
the first step of sodium silicate production: mixing the crushed coal gangue or coal ash and soda ash according to the weight ratio of 1: 50, uniformly mixing, smelting at high temperature (1400-1500 ℃, 1 hour), leaching with water (more than 100 ℃, 4-5 hours), filtering to remove impurities, and concentrating the filtrate to 45-46 Baume degree to obtain the sodium silicate.
The second step is to produce nano silicon dioxide: firstly, sodium silicate is prepared into a water glass solution (the modulus is 2.4-3.6, SiO)24-10 percent of nano silicon dioxide, then performing acid leaching in 5-20 percent of sulfuric acid (28-32 ℃ for 8-16 hours), heating to 80 ℃, stirring, adjusting the pH value to 5-7, curing for 20 minutes, and then performing filtration washing, drying and sorting to obtain the nano silicon dioxide. The nanometer silicon dioxide is active and has high purity.
The existing nano silicon dioxide production technology has the following defects:
(1) the primary particles are amorphous and have great difference with the crystalline particles in the aspect of physical characteristics, and the prior art synthesizes SiO2There are no conditions required for the crystallization of the particles in the process.
(2) The primary particles have narrow strength distribution, which can not meet the requirements of most fields, and the prior art does not have the condition that the primary particles are beyond the size of 15-40 nm.
(3) The prior art has the problems of high energy consumption, large pollution, high safety risk, large environmental protection pressure and the like. According to the characteristics of the existing process, the process has the technical processes of using flammable, explosive, toxic, strong acid and other raw materials, and high temperature and high pressure.
(4) The existing high-purity product process has high cost (determined by process characteristics).
(5) The existing low-cost product has low purity (determined by process characteristics).
Disclosure of Invention
In view of the above technical problems in the related art, the present invention provides a process for physically manufacturing nano-silica, which can overcome the above disadvantages in the prior art.
In order to achieve the technical purpose, the technical scheme of the invention is realized as follows:
a process for preparing nano silicon dioxide by a physical method comprises the following steps:
s1 raw material pretreatment: based on the weight portion, 1 portion of crystalline SiO2Adding the mixture into 0.8-1.5 parts of deionized water containing ammonium salt for primary dispersion to form slurry;
s2 surface treatment of raw material particles: adding a proper amount of surface treating agent into the slurry subjected to primary dispersion, and treating the slurry by using a dispersion machine;
s3, primary crushing and particle dispersing: conveying the dispersed slurry to a sand mill, and grinding for 1.5-3 hours by using zirconia microspheres with the diameter of 0.2-0.4mm as grinding media;
s4, secondary crushing and particle dispersing: continuously grinding for 6-11 hours, adjusting the particle size of the grinding medium to 0.5-2.5mm in the grinding process, adding an auxiliary agent with the mass of 0.5-4% of the powder, and adjusting the solid content by using deionized water;
s5 homogenization: and (3) conveying the continuously produced slurry to a stirring tank for stirring and homogenizing, and adding an auxiliary agent with the powder mass of 0.2-1.2% in the process.
Further, the process for manufacturing the nano silicon dioxide by the physical method comprises the following steps: s6 drying: drying the slurry to obtain powder nano SiO2。
Further, after the solid content is adjusted by deionized water in the step S4, the mixture is continuously ground for 0.1 to 5 hours, and an auxiliary agent with the powder mass of 0.2 to 3 percent is added in the grinding process.
Further, the concentration of the ammonium salt in the deionized water in step S1 is 0.5 to 3 wt%.
Further, the time for the treatment with the disperser in step S2 is 0.5 to 1.5 hours.
Further, 0.1 to 1.5wt% of ammonium salt is added during the grinding process of step S3.
The invention has the beneficial effects that: the indexes of the grain crystalline state and the granularity range of the product prepared by the process for preparing the nano silicon dioxide by the physical method can not be reached by the prior process technology; on the basis that the product purity reaches more than 99.9 percent, the process can meet the requirements of different industries such as chemical industry, electronics, integrated circuit wafers, LED substrate materials CMP (chemical mechanical polishing) and the like, and presents physical and chemical characteristics different from products manufactured by a non-physical manufacturing process; the solid content of the aqueous slurry of the product prepared by the invention can reach 50.5%, and the dispersion time at normal temperature is more than 180 days. Compared with the existing products with the same purity in the market (except the difference between the crystal form and the primary granularity and the process), the process cost for preparing the nano silicon dioxide by the physical method is less than 50 percent, mainly reducing the raw materials and the energy consumption and realizing the process conditions; the process disclosed by the invention has no dangerous raw materials such as inflammable, explosive, toxic, strong acid, strong alkali and the like, has no high-temperature and high-pressure process, and reduces the production cost and the risks of safety and environmental protection.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 shows a powder of nano SiO in accordance with an embodiment of the present invention2Electron micrograph of the product.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments that can be derived by one of ordinary skill in the art from the embodiments given herein are intended to be within the scope of the present invention.
Example 1
S1 crystal type SiO with purity not less than 99.95%, D50=1um, D100 not more than 10um21kg of the aqueous dispersion solution was added to 0.8kg of deionized water containing 0.5wt% of ammonium salt in batches to carry out preliminary dispersion to form a slurry;
s2, adding 1wt% of 8030 surface treating agent into the slurry subjected to primary dispersion, and treating for 1.5 hours by using a dispersion machine;
s3 first-stage crushing and particle dispersing steps: conveying the dispersed slurry to a sand mill (the impeller of the sand mill adopts a polyurethane material, the inner cylinder adopts a silicon carbide material, and the sand mill is vertical), grinding a medium which adopts zirconia micro-beads with the diameter of 0.2mm at the rotating speed of 700 r/min for 1.5 hours, and adding 0.1wt% of ammonium salt in the middle;
s4 secondary crushing and particle dispersing steps: continuing to continue the step S36 hours, adjusting the grain diameter of the grinding medium to 0.5mm in the process, rotating at 650 r/min, adding 9002 auxiliary agent with the powder mass of 0.5wt%, and adjusting the solid content to the required index by deionized water;
s5 particle size fraction, particle size distribution adjustment and particle dispersion steps: continuing to continue the step S for 40.1 hours, and adding 9006 percent of auxiliary agent with the powder mass of 0.2wt percent in the process;
s6 homogenization step: continuously produced slurry is conveyed to a stirring tank (polyethylene is lined on the inner wall of the stirring tank) for stirring and homogenization, the rotating speed of a stirring blade in the stirring tank is 5 r/min, and 9009 auxiliary agent with the powder mass of 0.2wt% is added in the process, so that the nano SiO2After the slurry is prepared, the slurry can be filled and hermetically stored, and the storage temperature is between 0 and 35 ℃;
s7 drying step: drying the slurry by a spray dryer to obtain powder nano SiO2The water content is adjusted according to the requirement, and the obtained powder nano SiO2The product is shown in figure 1.
Example 2
S1 crystal type SiO with purity not less than 99.95%, D50=3um, D100 not more than 15um21kg of deionized water containing 3wt% of ammonium salt pairs is added into 1.5kg of the mixture in batches for primary dispersion to form slurry;
s2, adding 3.5wt% of 8030 surface treating agent into the slurry subjected to primary dispersion, and treating for 0.5 hour by using a dispersion machine;
s3 first-stage crushing and particle dispersing steps: conveying the dispersed slurry to a sand mill (the impeller of the sand mill adopts a polyurethane material, the inner cylinder adopts a silicon carbide material, and the sand mill is vertical), grinding a medium which adopts zirconia micro-beads with the diameter of 0.4mm at the rotation speed of 950 rpm for 3 hours, and adding 1.5wt% of ammonium salt in the middle;
s4 secondary crushing and particle dispersing steps: continuing to continue the step S311 for hours, adjusting the grain diameter of the grinding medium to 2.5mm in the process, rotating at 950 rpm, adding 9002 auxiliary agent with the mass of 4wt% of the powder, and adjusting the solid content to the required index by using deionized water;
s5 particle size fraction, particle size distribution adjustment and particle dispersion steps: continuing to continue the step S45 hours, and adding 9006 auxiliary agents with the powder mass of 3wt% in the process;
s6 homogenization step: continuously produced slurry is conveyed to a stirring tank (polyethylene is lined on the inner wall of the stirring tank) for stirring and homogenization, the rotating speed of a stirring blade in the stirring tank is 20 r/min, and 9009 auxiliary agent with the powder mass of 1.2wt% is added in the process, so that the nano SiO2After the slurry is prepared, the slurry can be filled and hermetically stored, and the storage temperature is between 0 and 35 ℃;
s7 drying step: drying the slurry by a spray dryer to obtain powder nano SiO2The moisture is adjusted as required.
Example 3
S1 crystal form SiO with purity not less than 99.95%, D50=2um, D100 not more than 12um21kg of deionized water containing 1wt% of ammonium salt pairs is added into 1kg of the mixture in batches for primary dispersion to form slurry;
s2, adding 2wt% of 8030 surface treating agent into the slurry subjected to primary dispersion, and treating for 1 hour by using a dispersion machine;
s3 first-stage crushing and particle dispersing steps: conveying the dispersed slurry to a sand mill (the impeller of the sand mill is made of polyurethane material, the inner cylinder is made of silicon carbide material, and the sand mill is vertical), grinding a medium which is zirconia micro-beads with the diameter of 0.3mm at the rotating speed of 800 r/min for 2 hours, and adding 1wt% of ammonium salt in the middle;
s4 secondary crushing and particle dispersing steps: continuing to continue the step S38 hours, adjusting the grain diameter of the grinding medium to 1mm in the process, rotating at 700 r/min, adding 9002 percent of auxiliary agent with the mass of 2 weight percent of powder, and adjusting the solid content to the required index by deionized water;
s5 homogenization step: continuously produced slurry is conveyed to a stirring tank (polyethylene is lined on the inner wall of the stirring tank) for stirring and homogenization, the rotating speed of a stirring blade in the stirring tank is 10 r/min, and 9009 which accounts for 0.6 percent of the mass of powder is added in the processTo the nano SiO2After the slurry is prepared, the slurry can be filled and hermetically stored, and the storage temperature is between 0 and 35 ℃;
s6 drying step: drying the slurry by a spray dryer to obtain powder nano SiO2The moisture is adjusted as required.
The temperature of all the raw materials is between 5 and 29 ℃.
Powder of Nano SiO obtained in examples 1 to 32The crystal form and particle size of the product are shown in table 1.
TABLE 1 powder Nano SiO2Crystal form and particle size of product
Serial number | Crystal form | D50(nm) | D97(nm) | D100(nm) |
1 | Crystallization of | 73 | 115 | 177 |
2 | Crystallization of | 82 | 131 | 196 |
3 | Crystallization of | 88 | 164 | 220 |
In summary, by means of the above technical scheme of the present invention, the indexes of the grain crystalline state and the grain size range of the product produced by the process of the present invention are not reached by the existing process technology; the process can greatly improve the product purity and meet the requirements of different industries; compared with the existing products with the same purity in the market (except the difference between the crystal form and the primary granularity and the process), the process cost for preparing the nano silicon dioxide by the physical method is less than 50 percent, mainly reducing the raw materials and the energy consumption and realizing the process conditions; the process disclosed by the invention has no dangerous raw materials such as inflammable, explosive, toxic, strong acid, strong alkali and the like, has no high-temperature and high-pressure process, and reduces the production cost and the risks of safety and environmental protection.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (6)
1. A process for manufacturing nano silicon dioxide by a physical method is characterized by comprising the following steps:
s1 raw material pretreatment: based on the weight portion, 1 portion of crystalline SiO2Adding the mixture into 0.8-1.5 parts of deionized water containing ammonium salt for primary dispersion to form slurry;
s2 surface treatment of raw material particles: adding a proper amount of surface treating agent into the slurry subjected to primary dispersion, and treating the slurry by using a dispersion machine;
s3, primary crushing and particle dispersing: conveying the dispersed slurry to a sand mill, and grinding for 1.5-3 hours by using zirconia microspheres with the diameter of 0.2-0.4mm as grinding media;
s4, secondary crushing and particle dispersing: continuously grinding for 6-11 hours, adjusting the particle size of the grinding medium to 0.5-2.5mm in the grinding process, adding an auxiliary agent with the mass of 0.5-4% of the powder, and adjusting the solid content by using deionized water;
s5 homogenization: and (3) conveying the continuously produced slurry to a stirring tank for stirring and homogenizing, and adding an auxiliary agent with the powder mass of 0.2-1.2% in the process.
2. The process for physically fabricating nano-silica according to claim 1, further comprising:
s6 drying: drying the slurry to obtain powder nano SiO2。
3. The process for preparing nano-silica according to claim 1, wherein the solid content is adjusted by deionized water in step S4, and then the grinding is continued for 0.1-5 hours, and an auxiliary agent with a powder mass of 0.2-3% is added during the grinding process.
4. The process for physically manufacturing nano silica according to claim 1, wherein the concentration of ammonium salt in the deionized water in the step S1 is 0.5 to 3 wt%.
5. The process for physically manufacturing nano silica according to claim 1, wherein the time for the treatment with the disperser in the step S2 is 0.5 to 1.5 hours.
6. The process for physically manufacturing nano silica according to claim 1, wherein 0.1 to 1.5wt% of ammonium salt is added during the grinding process of the step S3.
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