Method for producing precipitated silicon dioxide through harmless treatment of organic silicon incineration solid waste

Abstract

The invention discloses a method for producing precipitated silicon dioxide through harmless treatment of organic silicon incineration solid waste. The method comprises the following steps: 1, mixing solid waste obtained by incinerating organic silicon with a sodium hydroxide solution with the mass concentration of 32% in proportion to obtain a mixture I; 2, the first mixture is heated and stirred at the heating temperature of 50-80 DEG C for 1 hour, silicon dioxide and sodium hydroxide in the solid waste fully react, and a second mixture is obtained; and step 3, filtering the mixture 2 through a filter I. According to the method for producing precipitated silica through harmless treatment of organic silicon incineration solid waste, hazardous waste obtained through incineration is subjected to harmless treatment, precipitated silica is produced, and the method not only can convert the hazardous waste into a precipitated silica product, but also can convert the hazardous waste into a precipitated silica product. And the greenhouse gas CO2 can be converted into a Na2CO3 product, so that the hazardous waste treatment cost of an organic silicon factory is reduced, and a product with a certain value is obtained.

Description

Technical Field

[0001] This invention relates to the field of harmless treatment technology for organosilicon incineration solid waste, specifically a method for producing precipitated silica through harmless treatment of organosilicon incineration solid waste. Background Technology

[0002] With the continuous development of society, people's demand for organosilicon products is increasing. The production process of organosilicon products generates a large amount of waste gas and waste liquid. As organosilicon production capacity continues to increase, the amount of waste gas and waste liquid generated is also increasing. The waste gas and waste liquid from organosilicon mainly include toxic and harmful substances such as chloromethane and various methylchlorosilanes. Currently, the main methods for treating organosilicon waste gas and liquid are waste gas incineration and dilute hydrochloric acid recovery. The main steps of this method are: High-temperature incineration: The organosilicon waste gas and liquid are incinerated at high temperature in an incinerator, turning it into flue gas (the flue gas mainly consists of hydrogen chloride gas, silica particles, carbon dioxide, etc.); Preheating boiler recovery: The high-temperature flue gas undergoes heat recovery in a preheating boiler, reducing the flue gas temperature to around 250℃ and simultaneously generating saturated steam; Quenching tower cooling: After heat recovery, the flue gas temperature remains high, requiring further cooling in a quenching tower using wet hydrochloric acid spraying to reduce the temperature to around 60℃; Wet spray dust removal: After the flue gas from the quenching tower undergoes wet spray dust removal with circulating dilute acid, most of the silica particles are separated from the flue gas; HCl absorption: The dust-removed flue gas further absorbs HCl using circulating dilute hydrochloric acid, and the resulting dilute hydrochloric acid can be recycled and reused, while the flue gas meets the corresponding emission standards. Although this method can yield some recyclable dilute acid, the dilute acid has a high solid content, so its recycling value is low. In addition, most of the silica particles obtained from incineration are classified as hazardous waste and still need to be treated. Therefore, we propose a method for the harmless treatment of organosilicon incineration solid waste to produce precipitated silica. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the existing defects and provide a method for harmlessly treating organosilicon incineration solid waste to produce precipitated silica. By harmlessly treating the hazardous waste obtained from incineration and producing precipitated silica, the problems in the background technology can be effectively solved.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for producing precipitated silica through harmless treatment of organosilicon incineration solid waste, comprising the following steps; Step 1: Mix the solid waste obtained from the incineration of organosilicon with a sodium hydroxide solution of a certain concentration according to the specified ratio to obtain mixture 1; Step 2: Heat and stir mixture 1 at a temperature of 50-80℃ for 1 hour to allow the silica and sodium hydroxide in the solid waste to react fully, thus obtaining mixture 2. Step 3: Filter mixture 2 through filter press 1 to separate filter cake residue and sodium silicate solution; Step 4: In the reactor, a fixed amount of CO2 gas is introduced into the sodium silicate solution by bubbling to control the pH of the reaction system to less than 6.5. At the same time, the reactor is heated with high-temperature steam to ensure the reaction temperature and complete conversion of sodium silicate. Step 5: After reacting for 2-4 hours, transfer the material to a slurry tank for settling. Step 6: After settling, filter the material through filter press 2 and rinse the filter cake with clean water to remove the Na2CO3 adhering to the surface. Step 7: Dry and grind the filter cake obtained in Step 6 at 200-400℃ to obtain the precipitated silica product; Step 8: The filtrate obtained in Step 6 is evaporated, concentrated, and cooled to crystallize, yielding solid Na2CO3. By harmlessly treating the hazardous waste obtained from incineration and producing precipitated silica, this method can not only convert hazardous waste into precipitated silica products, but also convert greenhouse gas CO2 into Na2CO3 products. This reduces the hazardous waste treatment costs of organosilicon plants and yields products with certain value.

[0005] Furthermore, in step one, the mass ratio of solid waste to sodium hydroxide solution is 1:4-6, and the concentration of sodium hydroxide solution is 30%-35%, preferably 32%. This ratio ensures that the silica in the solid waste reacts fully with the sodium hydroxide, avoiding incomplete reaction and solid waste residue due to insufficient sodium hydroxide, while also preventing waste of raw materials and subsequent processing burden due to excessive sodium hydroxide, thus improving the utilization rate of raw materials while ensuring reaction efficiency.

[0006] Furthermore, the stirring rate in step two is 150-250 r / min. This rate allows the solid waste in mixture one to come into full contact with the sodium hydroxide solution and mix evenly, accelerating the reaction rate and ensuring that silicon dioxide and sodium hydroxide react efficiently within 1 hour. This avoids insufficient reaction due to slow stirring or excessive energy consumption due to excessive stirring.

[0007] Furthermore, in steps three and six, both filter one and filter two are plate and frame filters or vacuum filters with a filtration pressure of 0.2-0.5 MPa. This equipment and pressure parameters can effectively separate the filter cake and solution in the mixture, ensuring filtration effect and efficiency. This avoids slow filtration speed and incomplete separation due to excessively low pressure, while also preventing damage to the equipment or splashing of filtrate due to excessively high pressure, thus ensuring the purity of raw materials in subsequent processes.

[0008] Furthermore, the high-temperature steam heating in step four maintains the reaction temperature in the reactor at 50-90°C. This temperature range promotes the reaction between sodium silicate and CO2, accelerates the reaction rate, and ensures complete reaction. It avoids slow or incomplete reaction due to excessively low temperature, or increased energy consumption and decreased CO2 solubility due to excessively high temperature, which would affect the reaction effect.

[0009] Furthermore, in step four, the gas flow rate of the bubbling is 0.5-2 m³ / h, and the purity of the CO2 gas is not less than 95%. This flow rate ensures that the CO2 and sodium silicate solution can fully contact and react, and the purity can reduce the interference of impurities on the reaction, ensuring that the sodium silicate is completely converted into the target product. This avoids incomplete reaction due to too small a flow rate or waste of CO2 due to too large a flow rate, as well as insufficient purity affecting the purity of the product.

[0010] Furthermore, the drying time in step seven is 2-5 hours, and the particle size of the ground product is 100-300 mesh. This time ensures that the filter cake is fully dried and the moisture is removed. The particle size range ensures that the silica product meets the application requirements. This avoids both excessively short drying time leading to high product moisture content and excessively long drying time increasing energy consumption. At the same time, the appropriate particle size ensures the performance of the product.

[0011] Furthermore, the evaporation and concentration temperature in step eight is 80-110℃, and the final temperature for cooling and crystallization is 10-30℃. This concentration temperature can efficiently evaporate water and increase the solution concentration, while the crystallization temperature can promote the full precipitation of Na2CO3. This avoids both low evaporation efficiency due to excessively low concentration temperature and increased energy consumption due to excessively high concentration temperature. At the same time, the appropriate crystallization temperature ensures the yield and purity of Na2CO3.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: The method for producing precipitated silica through the harmless treatment of organosilicon incineration solid waste has the following advantages: 1. Realize the resource utilization of hazardous waste, transform the silica hazardous waste generated from organosilicon incineration into silica products with application value through precipitation method, and at the same time absorb greenhouse gas CO2 to generate Na2CO3 solid, thereby reducing hazardous waste treatment costs and increasing the economic benefits of the factory.

[0013] 2. It conforms to the concepts of energy conservation, emission reduction and circular economy, and avoids the problems of low value of dilute acid recovery and resource waste caused by hazardous waste treatment in existing technologies. It realizes the recycling of resources while treating pollutants and reduces the burden on the environment. Attached Figure Description

[0014] Figure 1 This is a flowchart of a method for producing precipitated silica through the harmless treatment of organosilicon incineration solid waste according to the present invention. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Please see Figure 1 The present invention provides the following technical solutions: Example 1: A method for producing precipitated silica through harmless treatment of organosilicon incineration solid waste, comprising the following steps: Mixing: Take 100 kg of organosilicon incineration solid waste (silicon dioxide content 90%), add 400 kg of 32% sodium hydroxide solution at a ratio of 1:4, and the reaction SiO2 + NaOH → Na2SiO3 + H2O will occur to obtain mixture one; Reaction: Mixture 1 is heated and stirred in a dissolving tank at 60°C for one hour to allow silicon dioxide and sodium hydroxide to react fully, resulting in Mixture 2 (the completion of the reaction is determined by the amount of silica colloid or precipitate produced). Filtration: A filter press was used for two-stage filtration of the mixture at a pressure of 0.3 MPa, resulting in a filter cake (approximately 4 kg of impurities) and a sodium silicate solution. Carbonization reaction: Sodium silicate solution is fed into the reactor and heated to 60°C. CO2 gas is introduced at a bubbling flow rate of 1.0 m³ / h. The gas is stopped when the pH reaches 6.3. The total reaction time is 2.5 hours. The reaction that occurs is: Na2SiO3 + CO2 + H2O = Na2CO3 + H2SiO3, which completely converts sodium silicate. Settling: The material is fed into a slurry tank and allowed to settle for 1 hour; Washing and filtration: The material after settling is filtered through a filter press, and the filter cake is rinsed with clean water to remove Na2CO3 adhering to the surface. Preparation of silica: The filter cake was dried at 250℃ for 3 hours, and the reaction H2SiO3——SiO2+H2O occurred (under the condition of heating at 250℃). Then it was ground to 200 mesh to obtain 83kg of silica product with a purity of over 99%. Preparation of sodium carbonate: The filtrate was evaporated and concentrated to 50% at 90℃, and then cooled to 20℃ to crystallize, yielding 86 kg of Na2CO3 solid.

[0017] Example 2: A method for producing precipitated silica through harmless treatment of organosilicon incineration solid waste, comprising the following steps: Mixing: Take 150 kg of organosilicon incineration solid waste (silicon dioxide content 89%), add 750 kg of 32% sodium hydroxide solution at a ratio of 1:5, and the reaction SiO2 + NaOH → Na2SiO3 + H2O will occur to obtain mixture one; Reaction: Mixture 1 is heated and stirred in a dissolving tank at 70°C for one hour to allow silicon dioxide and sodium hydroxide to react fully, yielding Mixture 2 (the completion of the reaction is determined by the amount of silica colloid or precipitate produced). Filtration: The mixture was filtered using a filter press at a pressure of 0.4 MPa to separate the filter cake (approximately 6 kg of impurities) and a sodium silicate solution. Carbonization reaction: The reactor temperature is maintained at 70℃, CO2 gas is introduced, the bubbling flow rate is 1.5m³ / h, and the gas is stopped when the pH=6.0. The reaction time is 3 hours. The reaction that occurs is: Na2SiO3+CO2+H2O=Na2CO3+H2SiO3, which completely converts sodium silicate. Settling: The material is placed in a slurry tank and allowed to stand for 1.2 hours; Washing and filtration: The material after settling is filtered through a filter press, and the filter cake is rinsed with clean water to remove Na2CO3 adhering to the surface. Preparation of silica: The filter cake was dried at 300℃ for 2.5 hours, and the reaction H2SiO3——SiO2+H2O occurred (under the condition of heating at 300℃). Then it was ground to 150 mesh to obtain 128 kg of silica product with a purity of over 99%. Preparation of sodium carbonate: The filtrate was concentrated to 50% at 100℃, cooled to 15℃ for crystallization, yielding 132 kg of solid Na2CO3. Example 3: A method for producing precipitated silica through harmless treatment of organosilicon incineration solid waste, comprising the following steps: Mixing: Take 200 kg of organosilicon incineration solid waste (silicon dioxide content 91%), add 1200 kg of 32% sodium hydroxide solution at a ratio of 1:6, and the reaction SiO2 + NaOH → Na2SiO3 + H2O will occur to obtain mixture one; Reaction: Mixture 1 is heated and stirred in a dissolving tank at 80°C for one hour to allow silicon dioxide and sodium hydroxide to react fully, resulting in Mixture 2 (the completion of the reaction is determined by the amount of silica colloid or precipitate produced). Filtration: The mixture was filtered using a filter press at a pressure of 0.35 MPa to separate the filter cake (approximately 7 kg of impurities) and a sodium silicate solution. Carbonization reaction: The reactor temperature is 80℃, CO2 gas is introduced, the bubbling flow rate is 1.8m³ / h, the gas is stopped when the pH reaches 6.1, the reaction time is 3.5 hours, the reaction occurs: Na2SiO3+CO2+H2O=Na2CO3+H2SiO3 completely converts sodium silicate; Settling: Allow the material to settle for 1.5 hours; Washing and filtration: The material after settling is filtered through a filter press, and the filter cake is rinsed with clean water to remove Na2CO3 adhering to the surface. Preparation of silica: The filter cake was dried at 350℃ for 2 hours, and the reaction H2SiO3——SiO2+H2O occurred (under the condition of heating at 350℃). Then it was ground to 250 mesh to obtain 172 kg of silica product with a purity of over 99%. Preparation of sodium carbonate: The filtrate was concentrated to 50% at 95℃ and then cooled to 25℃ to crystallize, yielding 178 kg of Na2CO3 solid.

[0018] The present invention provides a method for the harmless treatment of organosilicon incineration solid waste to produce precipitated silica, as follows: Mixing: The solid waste obtained from organosilicon incineration is mixed with a sodium hydroxide solution of a certain concentration in a certain proportion, and the reaction occurs: SiO2 + 2NaOH = Na2SiO3 + H2O to obtain mixture one; Reaction: Mixture one is heated and stirred thoroughly to ensure that the silica in the solid waste reacts completely with the sodium hydroxide to obtain mixture two; Filtration: Mixture two is filtered through filter one to separate the filter cake (impurities) and sodium silicate solution; Carbonization reaction: In the reactor, a certain amount of CO2 gas is introduced into the sodium silicate solution by bubbling to control the pH of the reaction system to less than 6.5, while the reactor is heated with high-temperature steam to maintain the reaction temperature, and the reaction occurs. Reaction: Na2SiO3 + CO2 + H2O = Na2CO3 + H2SiO3 completely converts sodium silicate; Static precipitation: After reacting for 2-4 hours, the material is sent to a slurry tank for static precipitation; Washing and filtration: The material after static precipitation is filtered twice through a filter press, and the filter cake is rinsed with clean water to remove the Na2CO3 adhering to the surface; Preparation of silicon dioxide: The filter cake (H2SiO3) obtained in step 6 is dried and ground at 200-400℃, and the reaction occurs: H2SiO3 → SiO2 + H2O (under the condition of heating at 200-400℃), to obtain the precipitated silicon dioxide product; Preparation of sodium carbonate: The filtrate (containing Na2CO3) obtained in step 6 is evaporated, concentrated, cooled and crystallized to obtain solid Na2CO3.

[0019] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for the harmless treatment of organosilicon incineration solid waste to produce precipitated silica, characterized in that: Includes the following steps; Step 1: Mix the solid waste obtained from the incineration of organosilicon with a sodium hydroxide solution of a certain concentration according to the specified ratio to obtain mixture 1; Step 2: Heat and stir mixture 1 at a temperature of 50-80℃ for 1 hour to allow the silica and sodium hydroxide in the solid waste to react fully, thus obtaining mixture 2. Step 3: Filter mixture 2 through filter press 1 to separate filter cake residue and sodium silicate solution; Step 4: In the reactor, a fixed amount of CO2 gas is introduced into the sodium silicate solution by bubbling to control the pH of the reaction system to less than 6.

5. At the same time, the reactor is heated with high-temperature steam to ensure the reaction temperature and complete conversion of sodium silicate. Step 5: After reacting for 2-4 hours, transfer the material to a slurry tank for settling. Step 6: After settling, filter the material through filter press 2 and rinse the filter cake with clean water to remove the Na2CO3 adhering to the surface. Step 7: Dry and grind the filter cake obtained in Step 6 at 200-400℃ to obtain the precipitated silica product; Step 8: The filtrate obtained in Step 6 is evaporated, concentrated, and cooled to crystallize, yielding solid Na2CO3.

2. The method for producing precipitated silica through harmless treatment of organosilicon incineration solid waste according to claim 1, characterized in that: In step one, the mass ratio of solid waste to sodium hydroxide solution is 1:4-6, and the concentration of sodium hydroxide solution is 30%-35%.

3. The method for producing precipitated silica through harmless treatment of organosilicon incineration solid waste according to claim 1, characterized in that: The stirring rate in step two is 150-250 r / min.

4. The method for producing precipitated silica through harmless treatment of organosilicon incineration solid waste according to claim 1, characterized in that: In steps three and six, both filter one and filter two are plate and frame filters or vacuum filters, with a filtration pressure of 0.2-0.5 MPa.

5. The method for producing precipitated silica through harmless treatment of organosilicon incineration solid waste according to claim 1, characterized in that: The high-temperature steam heating in step four maintains the reaction temperature inside the reactor at 50-90℃.

6. The method for producing precipitated silica through harmless treatment of organosilicon incineration solid waste according to claim 1, characterized in that: In step four, the gas flow rate for bubbling is 0.5-2 m³ / h, and the purity of the CO2 gas is not less than 95%.

7. The method for producing precipitated silica through harmless treatment of organosilicon incineration solid waste according to claim 1, characterized in that: The drying time in step seven is 2-5 hours, and the particle size of the ground product is 100-300 mesh.

8. The method for producing precipitated silica through harmless treatment of organosilicon incineration solid waste according to claim 1, characterized in that: The evaporation and concentration temperature in step eight is 80-110℃, and the final temperature for cooling and crystallization is 10-30℃.

Images