Green production process of high silica glass fiber

Abstract

The application discloses a green production process of high-silica glass fiber, which is from raw materials of binary-component sodium silicate glass fiber to production and processing of high-silica glass fiber and products, and a series of purification processes are performed on a large amount of chemical raw materials and energy consumed in treatment of acid-containing wastewater and solid waste miscellaneous salt to achieve product standard recycling and reuse of industrial sodium sulfate salt and sale as by-products, and the production process is matched with an environment-friendly treatment and disposal of auxiliary materials for regeneration and utilization, effectively solving problems of large consumption of alkali in neutralization of the acid-containing wastewater and large cost of subsequent treatment of the solid salt, realizing recycling of the organic matter, recycling of the acid-containing wastewater and recycling of the solid salt as by-products, and conforming to the development concept of green and low carbon.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high silica glass fiber production, in particular to a green production process of high silica glass fiber. BACKGROUND

[0002] High silica glass fiber yarn has the characteristics of corrosion resistance, high temperature resistance, etc., and is mainly used for various reinforced, corrosion-resistant, heat-insulating textiles, and is widely used in the fields of aviation, aerospace, etc. High silica glass fiber and various products can generally be prepared by preparing alkali-containing glass fiber. Although the raw material components for preparing high silica glass fiber and its products are different, the SiO content in the fiber can reach 94%-98% after acid treatment process, and can be used in high temperature environment of 900-1000℃ for a long time.

[0003] The traditional high-silica glass fiber process is as follows: Step one: the glass fiber containing alkali produced by drawing is used as raw material of high-silica glass fiber and its products to produce related semi-finished products of glass fiber containing alkali through relevant processing (chopping, spinning, etc.); Step two: the semi-finished product of glass fiber containing alkali produced in step one is packed or wound on a special tool for acid treatment; Step three: the semi-finished product of glass fiber containing alkali packed or wound in step two is put into a circulating acid solution of a certain concentration, and the temperature of the acid solution and the acid leaching time are controlled, so that high-silica semi-finished products with SiO2 content greater than 96% are obtained; Step four: in order to obtain clean high-silica finished products, the high-silica semi-finished products filtered out in step three need to be cleaned, and since inorganic salt crystals generated by acid leaching treatment will remain on the surface of the high-silica semi-finished products, the high-silica semi-finished products need to be cleaned in circulating hot water with energy-controlled temperature of 40-55°C, so that the PH value of the surface of the high-silica semi-finished products reaches 6-8; Step five: the high-silica semi-finished products rinsed in step four are dried by microwave radiation heating and auxiliary hot air circulation, etc., to obtain high-silica semi-finished products; Step six: the high-silica semi-finished products in step five are packaged and stored after passing the detection; Step seven: step three is repeated in the acid treatment liquid for multiple times, and after the high-silica semi-finished products with SiO2 content greater than 96% are obtained, the acid treatment liquid begins to enrich inorganic salt, and after reaching a certain concentration of inorganic salt, the surface of the high-silica semi-finished products is secondarily contaminated, which increases the cleaning difficulty of step four, so the acid treatment liquid cannot be repeatedly used after the inorganic salt reaches the process concentration; Step eight: the waste acid treatment liquid in step seven that cannot be repeatedly used is discharged to an intermediate storage tank, and the waste acid treatment liquid is first neutralized with alkali to adjust the acidic PH value to 6-8, forming a mixed solution of high-concentration inorganic salt of neutralization reaction and inorganic miscellaneous salt generated by acid leaching; Step nine: the mixed solution of high-concentration inorganic salt of neutralization reaction and inorganic miscellaneous salt of acid leaching in step eight is separated by evaporation crystallization, etc., to precipitate a large amount of inorganic miscellaneous salt mixture, and this part of inorganic miscellaneous salt is disposed according to the relevant environmental protection policy and requirement; Step ten: the 40-55°C cleaning acid water in step four is discharged to a neutralization reaction tank, and the cleaning acid water in the neutralization reaction tank is adjusted to be neutral and low-concentration inorganic salt water through acid-base neutralization reaction, and this part of low-concentration inorganic salt water is discharged to a professional production wastewater treatment site for ultrafiltration desalination treatment, etc., and finally reaches the environmental protection requirement for discharge.

[0004] The above high-silica glass fiber is obtained by using glass fiber containing alkali produced by drawing as raw material, and going through relevant processing, acid leaching treatment, water washing and drying, etc. main processes. These glass fiber raw materials consume a lot of various energy and chemical raw materials during the acid treatment, water washing and drying processes, and at the same time, related environmental protection post-treatment equipment and facilities are needed to treat the production waste liquid and solid waste to reach the standard for discharge and disposal.

[0005] In the production of high silica glass fiber, alkali-containing glass fiber is used for acid leaching treatment in acid solution to remove metal oxides and leave porous silica skeleton. Inorganic salts are generated during the acid leaching treatment process. As the acid treatment progresses, the concentration of inorganic salts in the acid solution gradually increases. When the concentration of inorganic salts in the acid solution reaches a limit, it will affect the quality of high silica products and other process production. At this time, the acid solution and inorganic salt mixture need to be discharged for related disposal before being discharged. At the same time, due to the product characteristics of high silica glass fiber and products after acid treatment, warm water is used to dissolve the inorganic salts on the surface of the fiber for washing and drying to ensure that the surface of the obtained high silica glass fiber and products is neutral and the fiber surface does not remain inorganic salts. A large amount of acidic wastewater containing inorganic salts is also generated during washing and needs to be treated before being discharged.

[0006] The common technical solution for the acid leaching of alkali-containing glass fiber and the mixture of acid solution and inorganic salts is to adjust the pH value of the above waste acid treatment liquid to 6-8 with alkali, and then obtain organic impurities by evaporation crystallization, and then dispose according to environmental protection requirements. A large amount of acidic wastewater containing inorganic salts is also generated during the washing of glass fiber and products, which is also adjusted to a pH value of 6-8 with alkali, and then discharged to the production wastewater treatment station. The wastewater is treated to reach the standard by flocculation, precipitation, and other process technical measures, and then discharged to the municipal sewage pipe network. The associated waste liquid and wastewater generated during the production of high silica glass fiber and products require the manufacturer to spend a large amount of treatment raw materials, energy, and disposal fees to complete, which does not conform to the concept and direction of future green development.

[0007] The specific defects of the existing process are as follows:

[0008] 1. High silica glass fiber is obtained by processing alkali-containing glass fiber as raw material through related processes. The composition of alkali-containing glass fiber also limits the related subsequent processing and production process to a great extent. Therefore, a relatively green, low-cost, and efficient alkali-containing glass fiber formula is needed as the raw material for high silica fiber production, and related other green process technologies are needed to produce high silica glass fiber products.

[0009] 2. Alkali-containing glass fiber is used as raw material for acid leaching treatment. As the acid leaching process progresses, inorganic salts begin to accumulate in the acid solution. As the concentration of inorganic salts increases, the acid treatment liquid cannot be reused and needs to be discharged for waste liquid treatment, causing waste of acid solution. A process technology is needed to ensure the continuous reuse of acid treatment liquid.

[0010] 3. The acid treatment liquid cannot be reused and needs to be discharged for process treatment, which requires the use of high-cost alkali for neutralization treatment. A process method is needed that does not require the use of high-cost alkali for neutralizing acid treatment waste liquid.

[0011] 4. The inorganic salt solution generated again by the neutralization reaction of the acid treatment solution requires supporting evaporation and crystallization equipment and energy sources such as steam and electricity to precipitate the inorganic salts from the neutralization reaction.

[0012] 5. The solid waste salts produced by evaporation and crystallization have a certain impact on the environment. At present, they can only be entrusted to other third-party organizations or platforms for in-depth environmental protection treatment in accordance with environmental protection requirements, and the enterprise pays the relevant disposal fees.

[0013] 6. Because the high-silica fiber semi-finished product filtered by acid leaching contains residual acid, inorganic salt solution and inorganic salt crystals, a large amount of hot water is required for circulating cleaning in order to dissolve and clean the inorganic salt crystals on the residual high-silica glass fiber. In addition, a large amount of energy is required to heat the room temperature water to 40-55℃.

[0014] 7. After neutralization and adjustment, the cleaning water enters the production wastewater treatment system for environmental protection treatment to meet environmental protection requirements. Then it needs to be discharged into the park's sewage pipe network for further environmental protection treatment by the park's sewage treatment unit.

[0015] Therefore, there is an urgent need for an improved technology to solve the problems existing in the current technology. Summary of the Invention

[0016] The purpose of this invention is to provide a green production process for high-silica glass fiber, from the raw materials of alkali-containing glass fiber to the production and processing of high-silica glass fiber and products, and then to the environmentally friendly treatment, disposal and recycling of auxiliary materials used in the production process. This effectively solves the problems of high alkali consumption for neutralizing acidic wastewater and high subsequent treatment costs for solid salts. It realizes the recycling of organic matter, the recycling of acidic wastewater and the reuse of solid salt by-products, which is in line with the green and low-carbon development concept and solves the problems mentioned in the background technology.

[0017] To achieve the above objectives, the present invention provides the following technical solution: a green production process for high-silica glass fiber, comprising the following steps:

[0018] Step 1: Using sodium silicate glass fiber as raw material, it is processed into a semi-finished product of sodium silicate glass fiber;

[0019] Step 2: The semi-finished sodium silicate glass fiber from Step 1 is circulated and reacted with a certain concentration of dilute sulfuric acid in a container according to the acid leaching process, and sodium sulfate is generated in the reaction.

[0020] Step three: the sodium sulfate produced in step two is co-dissolved with the dilute sulfuric acid solution, and as the acid leaching process circulates, the concentration of sodium sulfate in the dilute sulfuric acid solution increases to saturation, and sodium sulfate begins to crystallize and is trapped in the high-silica glass fiber semi-finished product, which will affect the quality of the high-silica product, and cannot be used for acid leaching, so the sodium sulfate and dilute sulfuric acid co-dissolution solution needs to be discharged;

[0021] Step four: using the low-temperature crystallization characteristics of sodium sulfate, and assisted by a set of process equipment, the sodium sulfate and dilute sulfuric acid co-dissolution solution in step three is cooled by a refrigerated liquid exchanger, causing sodium sulfate in the sodium sulfate and dilute sulfuric acid co-dissolution solution to crystallize and produce sodium sulfate decahydrate, which is then separated by a centrifuge;

[0022] Step five: the dilute sulfuric acid solution separated by the centrifuge in step four is returned to the acid leaching treatment tank and adjusted to the required sulfuric acid concentration for acid leaching treatment of sodium-silicon glass fiber, and the sulfuric acid solution is used for secondary circulation;

[0023] Step six: the sodium sulfate decahydrate separated by the centrifuge in step four is then melted, diluted, and the pH of the sodium sulfate solution is adjusted with hot water, and then the solution is transferred to an MVR for evaporation and crystallization to obtain high-quality anhydrous sodium sulfate;

[0024] Step seven: the anhydrous sodium sulfate produced in step six is tested and stored as a byproduct, part of which is used for high-silica raw material production, and the rest is directly sold on the market as a byproduct;

[0025] Step eight: in step two, the semi-finished product of sodium-silicon glass fiber reacts with a certain concentration of dilute sulfuric acid to produce sodium sulfate and high-silica glass fiber or product semi-finished product, but due to the generation of inorganic salt crystals during acid leaching treatment, the inorganic salt crystals are left on the surface of the high-silica or product semi-finished product, and hot water with a temperature of 40-55℃ is used to dissolve and clean the inorganic salt crystals left on the surface of the high-silica or product semi-finished product;

[0026] Step nine: the hot water used in step eight is controlled to be above the solubility of sodium sulfate;

[0027] Step ten: combine the cleaning hot water required in step nine with the low-temperature refrigerant medium required for low-temperature crystallization of sodium sulfate in step four;

[0028] Step eleven: in step six, the ten-water sodium sulfate needs to be heated and melted, and a hot water coil type atmospheric hot melting tank is used, combined with the melting heat of the ten-water sodium sulfate, a large amount of hot water generated by the heat pump in step ten is circulated in the hot melting tank coil to melt the ten-water sodium sulfate in the hot melting tank;

[0029] Step twelve: the residual inorganic crystalline salt on the surface of high silica or product semi-finished product is dissolved and cleaned in step eight, and the generated cleaning wastewater is low-acid concentration wastewater, which is neutralized and adjusted to be neutral through online PH detection;

[0030] Step thirteen: the cleaning wastewater adjusted and neutralized in step twelve is subjected to physical rough filtration and fine filtration to remove a small amount of high silica fiber fluff mixed in the cleaning water;

[0031] Step fourteen: the cleaning water in which the high silica fiber fluff is removed in step thirteen is subjected to multi-stage reverse osmosis filtration desalination to generate reclaimed water and high-salt concentrated water, and the reclaimed water is reused in the cleaning process for the dissolution and cleaning of the inorganic crystalline salt;

[0032] Step fifteen: the high-salt concentrated water generated in step fourteen is frozen and exchanged with the sodium sulfate and dilute sulfuric acid co-solution in step three to make sodium sulfate in the sodium sulfate and dilute sulfuric acid co-solution precipitate to produce sodium sulfate decahydrate, and then the sodium sulfate decahydrate is subjected to solid-liquid separation through a centrifuge, thereby forming an energy-saving and closed-cycle green production process technology.

[0033] Preferably, the green production process of high-silica glass fiber provided by the application has the following technical scheme: the concentration of the dilute sulfuric acid in step two is 8-15%.

[0034] Preferably, the green production process of high-silica glass fiber provided by the application has the following technical scheme: one set of process equipment in step four is equipped with low-temperature refrigerant-5℃ process cooling equipment, the sodium sulfate and dilute sulfuric acid co-solution is controlled at 0-10℃, and then the sodium sulfate is crystallized and separated out through a large circulation crystallizer.

[0035] Preferably, the green production process of high-silica glass fiber provided by the application has the following technical scheme: the sodium sulfate and dilute sulfuric acid co-solution in step three is washed by the hot water required in step eight, and the washing hot water is controlled at 40-55℃ in combination with the solubility and temperature attribute relationship of sodium sulfate.

[0036] Preferably, the green production process of high-silica glass fiber provided by the application has the following technical scheme: before the solid-liquid separated dilute sulfuric acid liquid returns to the acid leaching treatment tank, energy recovery and heat exchange for mother liquid precooling are increased, and countercurrent heat exchange is performed between the frozen crystallization liquid and the low-temperature dilute sulfuric acid liquid after low-temperature crystallization after the acid leaching treatment.

[0037] Preferably, the green production process of high-silica glass fiber provided by the application has the following technical scheme: the anhydrous sodium sulfate in step six is combined with the drying treatment and packaging of anhydrous sodium sulfate required by market customers, and finally inspected and produced as a byproduct into a warehouse.

[0038] Preferably, the present application provides a green production process of high silica glass fiber, wherein the middle water in step 14 is stored in a middle water pool, and hot water generated by a heat pump heat exchanger from the middle water pool is reused in the cleaning process for dissolving inorganic crystalline salt and cleaning.

[0039] Compared with the prior art, the present application has the following advantages:

[0040] By producing a binary component sodium silicate glass fiber (Na 2° mSiO2) as raw material to produce high silica glass fiber and products, the binary component sodium silicate glass has lower cost than other high silica glass fiber production raw materials, the main raw material composition is single, the acid treatment process is environmentally friendly and efficient, and it is also beneficial to the green recycling production and utilization and energy saving and emission reduction after treatment.

[0041] (2) Use sodium silicate glass fiber as raw material (Na2·mSiO2) to react with dilute sulfuric acid (H2SO4) of certain concentration, and generate sodium sulfate (Na2SO4). At this time, sodium sulfate and dilute sulfuric acid are in a common solution. With the circulation of the acid leaching process, the concentration of sodium sulfate in the dilute sulfuric acid solution increases. The dilute sulfuric acid cannot be recycled and is discharged to the sodium sulfate crystallization storage tank. By using the low-temperature crystallization characteristics of sodium sulfate, a set of process technology equipment is designed to make the sodium sulfate in the sodium sulfate and dilute sulfuric acid common solution precipitate to produce sodium sulfate decahydrate (Na2SO4·10H2O). Then, the solid-liquid separation is carried out by a centrifuge. The dilute sulfuric acid solution is returned to the acid leaching tank and adjusted to the required sulfuric acid concentration for acid leaching treatment of sodium silicate glass fiber. The sulfuric acid solution is recycled, which does not cause waste of sulfuric acid discharge treatment and does not need to use high-cost alkali for neutralization treatment. At the same time, it does not need to use steam, electricity and other energy to evaporate and crystallize the inorganic salt generated by the neutralization reaction, forming a green production process technology that can be recycled, greatly reducing production consumption, and achieving energy saving and emission reduction.

[0042] (3) The sodium sulfate and dilute sulfuric acid common solution after the reaction of sodium silicate glass fiber with dilute sulfuric acid of certain concentration is crystallized. A full-recovery heat pump technology is used to generate low-temperature refrigerant and exchange heat with the sodium sulfate and dilute sulfuric acid common solution, and then supplemented by crystallization circulation and centrifugal separation to precipitate sodium sulfate decahydrate. At the same time, after the acid leaching treatment of sodium silicate glass fiber, a certain amount of sodium sulfate crystallization is left between the fibers, which needs to be cleaned with a large amount of hot water. The full-recovery heat pump unit generates low-temperature refrigerant and a large amount of heat energy for heating and warming the cleaning water at the same time, which does not need to use steam or electricity to heat the cleaning water, realizing a green production process technology of comprehensive energy utilization.

[0043] (4) The hot water used for cleaning high silica glass fiber products is no longer neutralized and adjusted before entering the production wastewater treatment system for environmental protection treatment, but is online micro-neutralized and adjusted, then filtered coarsely, filtered finely, and then filtered by multi-stage reverse osmosis, and the concentrated filtered hot brine is collected into the molten crystal tank of sodium sulfate decahydrate produced in the crystallization centrifugation process, and the sodium sulfate decahydrate is fully dissolved (the sodium sulfate decahydrate is a supersaturated sodium sulfate solution after being heated and dissolved, and a certain proportion of unsaturated sodium sulfate solution is needed to supplement to completely dissolve), and at the same time, the molten crystal tank for dissolving sodium sulfate decahydrate adopts a double jacket structure, and the heat source also comes from the hot water generated by the heat pump unit. At the same time, the hot cleaning hot water is reused after being micro-neutralized and adjusted, filtered coarsely, filtered finely, and then filtered by multi-stage reverse osmosis, forming a green production process technology that saves energy and reduces energy consumption.

[0044] (5) Since the binary component sodium silicate glass fiber is used as the raw material for producing high silica glass fiber, and after reacting with dilute sulfuric acid, clean sodium sulfate decahydrate is produced by low-temperature crystallization, and then after melting and crystallizing and PH adjustment (after separation of sodium sulfate decahydrate, acid solution is left on the surface of the crystal), finally enters the evaporation system to produce high-quality anhydrous sodium sulfate (metam powder) as a byproduct, which meets the product standard of industrial anhydrous sodium sulfate. A part of the produced industrial anhydrous sodium sulfate (metam powder) is used as one of the raw materials for the production of sodium silicate glass fiber, and the other part is directly sold as a byproduct. The solid waste salt generated in the production process of high silica glass fiber is changed into anhydrous sodium sulfate that meets the product standard of industrial anhydrous sodium sulfate through a series of process technologies, forming a new green production process technology. DETAILED DESCRIPTION

[0045] The technical solutions of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0046] The present application provides a technical solution: a green production process of high silica glass fiber, comprising the following steps:

[0047] Step one: using sodium silicate glass fiber as raw material (Na2·mSiO2) to change the semi-finished product of sodium silicate glass fiber after processing;

[0048] Step two: the semi-finished product of sodium silicate glass fiber in step one is circulated and reacted with dilute sulfuric acid (H2SO4) with a concentration of 8-15% in the container according to the acid leaching process, and sodium sulfate (Na2SO4) is generated by the reaction;

[0049] Step three: The sodium sulfate produced in step two is co-dissolved with dilute sulfuric acid solution. As the acid leaching process circulates, the concentration of sodium sulfate in the dilute sulfuric acid solution increases to saturation. Sodium sulfate begins to crystallize and is trapped in the high-silica glass fiber semi-finished product, affecting the quality of the high-silica product. The sodium sulfate and dilute sulfuric acid solution cannot be used for acid leaching and needs to be discharged.

[0050] Step four: Using the low-temperature crystallization characteristics of sodium sulfate, a low-temperature refrigerant-5°C matching process cooling equipment is used to control the temperature of the sodium sulfate and dilute sulfuric acid co-solution at 0-10°C. Then, through a large circulation crystallizer, sodium sulfate is crystallized and separated out. The sodium sulfate and dilute sulfuric acid co-solution in step three is cooled by the freezing liquid, causing sodium sulfate to precipitate from the sodium sulfate and dilute sulfuric acid co-solution to produce sodium sulfate decahydrate (Na2SO4·10H2O). Then, solid-liquid separation is performed by a centrifuge.

[0051] Step five: The dilute sulfuric acid solution separated by the centrifuge in step four is returned to the acid leaching tank and adjusted to the required sulfuric acid concentration for acid leaching treatment of sodium-silicon glass fiber. Before returning to the acid leaching tank, heat exchange for energy recovery and mother liquor pre-cooling is added. After acid leaching and filtration, countercurrent heat exchange is performed between the frozen crystallization liquid and the low-temperature dilute sulfuric acid liquid after low-temperature crystallization. The sulfuric acid solution is used twice.

[0052] Step six: The sodium sulfate decahydrate separated by the centrifuge in step four is subjected to melting, dilution, and PH adjustment (the crystal surface is left with residual acid solution) using hot water. The sodium sulfate solution is then transferred to an MVR for evaporation crystallization to obtain high-quality anhydrous sodium sulfate. The anhydrous sodium sulfate is dried and packaged according to market customer needs. Finally, it is inspected and stored as a byproduct.

[0053] Step seven: The anhydrous sodium sulfate (Na2SO4) produced in step six is inspected according to the product standard of industrial anhydrous sodium sulfate GBT 6009-2014 and stored as a byproduct. A part is used for high-silica raw material production, and the other is directly sold on the market as a byproduct.

[0054] Step eight: In step two, the semi-finished product of sodium-silicon glass fiber reacts with dilute sulfuric acid of a certain concentration to produce sodium sulfate and high-silica glass fiber or product semi-finished product. However, due to the generation of inorganic salt crystals during acid leaching, the inorganic salt crystals remain on the surface of the high-silica or product semi-finished product. Hot water is needed to dissolve and clean the inorganic salt crystals remaining on the surface of the high-silica or product semi-finished product.

[0055] Step nine: The hot water needed in step eight needs to be controlled above the solubility of sodium sulfate based on the solubility and temperature properties of sodium sulfate.

[0056] Step ten: the washing hot water required in step nine and the low-temperature refrigerant medium required for the low-temperature crystallization of sodium sulfate in step four are exchanged cold, and the process invention uses a full-recovery heat pump unit to produce low-temperature refrigerant while also producing a large amount of heat energy for heating and warming the washing water, so that steam or electricity is no longer needed to heat the washing water, and a green production process technology of comprehensive energy utilization is achieved;

[0057] Step eleven: the ten-water sodium sulfate in step six needs to be heated and crystallized, and the process invention uses a hot water coil type atmospheric hot melting tank, combines the melting heat of the ten-water sodium sulfate, and uses the large amount of hot water produced by the heat pump in step ten to pass into and circulate in the hot melting tank coil to melt and crystallize the ten-water sodium sulfate in the hot melting tank;

[0058] Step twelve: the inorganic crystalline salt remaining on the surface of the high-silica or product semi-finished product in step eight is dissolved and washed to produce washing wastewater, which is a relatively complex component wastewater (high in salt and slightly acidic, and also containing a small amount of high-silica fiber fluff);

[0059] Step thirteen: the washing wastewater adjusted to neutral in step twelve is subjected to physical coarse filtration and fine filtration to remove the small amount of high-silica fiber fluff contained in the washing water;

[0060] Step fourteen: the washing water in which the high-silica fiber fluff is removed in step thirteen is subjected to multi-stage reverse osmosis filtration desalination to generate reclaimed water, which is stored in a reclaimed water pool, and the hot water generated by the heat pump heat exchanger from the reclaimed water pool is reused to the washing process for dissolving and washing inorganic crystalline salt;

[0061] Step fifteen: the high-salt concentrated water produced in step fourteen is subjected to freezing liquid exchange cold with the sodium sulfate and dilute sulfuric acid co-solution in step three to precipitate sodium sulfate in the sodium sulfate and dilute sulfuric acid co-solution to produce ten-water sodium sulfate (Na2SO4·10H2O), and then subjected to solid-liquid separation by a centrifuge to form a closed-cycle green production process technology that saves energy and reduces energy consumption. EMBODIMENT

[0062] A green production process of high-silica glass fiber, comprising the following steps:

[0063] Step one: using sodium-silicon glass fiber as raw material (Na2·mSiO2) to process sodium-silicon glass fiber semi-finished product;

[0064] Step two: the sodium-silicon glass fiber semi-finished product in step one is subjected to acid leaching process in a container with 12% dilute sulfuric acid (H2SO4) to react and generate sodium sulfate (Na2SO4);

[0065] Step three: The sodium sulfate produced in step two is co-dissolved with dilute sulfuric acid solution. As the acid leaching process circulates, the concentration of sodium sulfate in the dilute sulfuric acid solution increases to saturation. Sodium sulfate begins to crystallize and is trapped in the high-silica glass fiber semi-finished product, affecting the quality of the high-silica product. The sodium sulfate and dilute sulfuric acid solution co-dissolution cannot be used for acid leaching and needs to be discharged.

[0066] Step four: Utilizing the low-temperature crystallization characteristics of sodium sulfate, a low-temperature refrigerant-5°C matching process cooling equipment is used to control the temperature of the sodium sulfate and dilute sulfuric acid co-dissolution at 5°C. Then, through a large circulation crystallizer, sodium sulfate is crystallized and separated out. The sodium sulfate and dilute sulfuric acid co-dissolution in step three is cooled by the freezing liquid, causing the sodium sulfate in the sodium sulfate and dilute sulfuric acid co-dissolution to crystallize and produce sodium sulfate decahydrate (Na2SO4·10H2O). Then, solid-liquid separation is performed by a centrifuge.

[0067] Step five: The dilute sulfuric acid solution separated by the centrifuge in step four is returned to the acid leaching treatment tank and adjusted to the required sulfuric acid concentration for the acid leaching treatment of sodium-silicon glass fiber. Before returning to the acid leaching treatment tank, heat exchange for energy recovery and mother liquor pre-cooling is added. After acid leaching and filtration, countercurrent heat exchange is performed between the frozen crystallization liquid and the low-temperature dilute sulfuric acid liquid after low-temperature crystallization. The sulfuric acid solution is used for secondary circulation.

[0068] Step six: The sodium sulfate decahydrate separated by the centrifuge in step four is subjected to melting, dilution, and PH adjustment (the crystal surface after separation is residual acid solution) using hot water. The sodium sulfate solution is then transferred to an MVR for evaporation crystallization to obtain high-quality anhydrous sodium sulfate. The anhydrous sodium sulfate is dried and packaged according to market customer needs. Finally, it is inspected and produced as a byproduct for storage.

[0069] Step seven: The anhydrous sodium sulfate (Na2SO4) produced in step six is inspected according to the product standard of industrial anhydrous sodium sulfate GBT 6009-2014 and produced as a byproduct for storage. Part of it is used for high-silica raw material production, and the rest is directly marketed as a byproduct.

[0070] Step eight: In step two, the semi-finished product of sodium-silicon glass fiber reacts with dilute sulfuric acid of a certain concentration to produce sodium sulfate and high-silica glass fiber or product semi-finished product. However, due to the generation of inorganic salt crystals during acid leaching treatment, they are left on the surface of the high-silica or product semi-finished product. Hot water is needed to dissolve and clean the inorganic salt crystals left on the surface of the high-silica or product semi-finished product.

[0071] Step nine: The hot water needed in step eight needs to be controlled above the solubility of sodium sulfate, considering the solubility and temperature properties of sodium sulfate.

[0072] Step ten: the cleaning hot water required in step nine and the low-temperature refrigerant medium required for the low-temperature crystallization of sodium sulfate in step four are exchanged cold, and the heat pump unit used in the process invention produces low-temperature refrigerant while producing a large amount of heat energy for heating and warming the cleaning water, so that steam or electricity is no longer needed to heat the cleaning water, achieving a comprehensive energy utilization green production process technology;

[0073] Step eleven: the ten-water sodium sulfate needs to be heated and melted in step six, and the process invention uses a hot water coil type atmospheric hot melting tank, combines the melting heat of the ten-water sodium sulfate, and uses the large amount of hot water produced by the heat pump in step ten to pass into and circulate in the hot melting tank coil to melt the ten-water sodium sulfate in the hot melting tank;

[0074] Step twelve: the inorganic crystalline salt remaining on the surface of the high-silica or semi-finished product is dissolved and cleaned in step eight to produce cleaning wastewater, which is a relatively complex component of wastewater (the cleaning wastewater is acidic and has a high salt content, and also contains a small amount of high-silica fiber fluff); the low-acid concentration wastewater is neutralized to neutral by on-line PH detection and adjustment;

[0075] Step thirteen: the cleaning wastewater adjusted by neutralization in step twelve is physically coarsely filtered and finely filtered to remove the small amount of high-silica fiber fluff contained in the cleaning water;

[0076] Step fourteen: the cleaning water in which the high-silica fiber fluff is removed in step thirteen is further desalted by multi-stage reverse osmosis filtration to generate reclaimed water, which is stored in a reclaimed water pool, and the hot water generated by the heat pump heat exchanger from the reclaimed water pool is reused to the cleaning process for dissolving and cleaning the inorganic crystalline salt;

[0077] Step fifteen: the high-salt concentration water produced in step fourteen is introduced into step fourteen, and the sodium sulfate in the sodium sulfate and dilute sulfuric acid co-solution in step three is precipitated by freezing liquid cooling to produce ten-water sodium sulfate (Na2SO4·10H2O), and then solid-liquid separation is performed by a centrifuge, forming a closed-loop green production process technology that saves energy and reduces energy consumption.

[0078] The purpose of the process is to design a green production process for high-silica glass fiber, from the raw material of alkali-containing glass fiber to the production and processing of high-silica glass fiber and products, to the environmental protection treatment and disposal of auxiliary materials for the production process, etc. The problems of large amount of neutralization of acid-containing wastewater and large amount of solid salt treatment cost are effectively solved, the recycling of organic matter, the recycling of acid-containing wastewater and the recycling of solid salt are realized, and the development concept of green and low carbon is met.

[0079] The green production process technology of high silica glass fiber uses binary sodium silicate glass fiber as raw material to produce high silica glass fiber and products, and the binary sodium silicate glass fiber has lower cost, single composition, green and efficient acid treatment process, and is beneficial to green recycling and treatment of by-products.

[0080] The green production process technology of high silica glass fiber uses sulfuric acid to greenly acid treat binary sodium silicate glass fiber; after acid treatment, sodium sulfate and dilute sulfuric acid mixed solution is subjected to freezing crystallization process technology to precipitate sodium sulfate, and the dilute sulfuric acid solution can be used for acid treatment of binary sodium silicate glass fiber after sodium sulfate is precipitated, and the dilute sulfuric acid solution is recycled; all the refrigerant freezing media generated by using heat pump technology crystallize sodium sulfate in the mixed solution, and the heat generated by the heat pump technology is used for heating the washing water to heat the surface of the high silica glass fiber.

[0081] The green production process technology of high silica glass fiber uses a binary sodium silicate glass fiber as raw material to produce high silica glass fiber and products, and the binary sodium silicate glass fiber has lower cost, single composition, green and efficient acid treatment process, and is beneficial to green recycling and treatment of by-products.

[0082] The green production process technology of high silica glass fiber uses sodium-silicon glass fiber as raw material and reacts with dilute sulfuric acid of a certain concentration to generate sodium sulfate, which is a cosolute with dilute sulfuric acid. With the circulation of acid leaching process, the concentration of sodium sulfate in dilute sulfuric acid solution increases, and dilute sulfuric acid cannot be recycled and is discharged to a sodium sulfate crystallization storage tank. By using the low-temperature crystallization characteristics of sodium sulfate, a set of process technology equipment is designed to precipitate sodium sulfate from the cosolute of sodium sulfate and dilute sulfuric acid to produce sodium sulfate decahydrate, and then the sodium sulfate is separated by a centrifuge. The dilute sulfuric acid solution is returned to the acid leaching tank and adjusted to the required sulfuric acid concentration for acid leaching of sodium-silicon glass fiber. The sulfuric acid solution is recycled, which does not cause waste of sulfuric acid discharge and does not need to use high-cost alkali for neutralization treatment. At the same time, steam, electricity and other energy are not needed to evaporate and crystallize the inorganic salt generated by the neutralization reaction, forming a green production process technology that can be recycled, greatly reducing production consumption, and saving energy and reducing emissions.

[0083] The green production process technology of the high silica glass fiber is used for crystallizing the sodium sulfate and dilute sulfuric acid co-solution after the sodium silicate glass fiber is reacted with dilute sulfuric acid, heat exchange is carried out between low-temperature refrigerant and the sodium sulfate and dilute sulfuric acid co-solution by using the all-purpose recovery heat pump technology, and sodium sulfate decahydrate is separated out by crystallization circulation and centrifugal separation; meanwhile, after the sodium silicate glass fiber is acid leached, a certain amount of sodium sulfate crystal is left in the fibers, a large amount of hot water needs to be used for circulating cleaning, the all-purpose recovery heat pump unit generates low-temperature refrigerant and a large amount of heat energy is by-produced for heating and warming the cleaning water, steam or electric energy is no longer needed for heating the cleaning water, and a green production process technology of comprehensive energy utilization is realized.

[0084] The green production process technology of the high silica glass fiber is used for cleaning the hot water of the high silica glass fiber product, and the adjusted hot water no longer enters a production wastewater treatment system for environmental protection treatment, but is subjected to rough filtration, fine filtration, multi-stage reverse osmosis filtration, concentration and filtration of relatively concentrated hot brine, collection into a sodium sulfate decahydrate melting and crystallizing tank, full dissolution of the sodium sulfate decahydrate (the sodium sulfate decahydrate is over-saturated after being heated and melted, needs a certain proportion of unsaturated sodium sulfate solution for complete dissolution), meanwhile, the melting and crystallizing tank for melting and dissolving the sodium sulfate decahydrate adopts a double jacket structure, and the heat source is also from the hot water generated by the heat pump unit. Meanwhile, the hot cleaning hot water is subjected to rough filtration, fine filtration, multi-stage reverse osmosis and reuse of the middle water, and a green production process technology of energy saving and emission reduction is formed.

[0085] The green production process technology of the high silica glass fiber is used for crystallizing the sodium sulfate and dilute sulfuric acid co-solution after the sodium silicate glass fiber is reacted with dilute sulfuric acid, heat exchange is carried out between low-temperature refrigerant and the sodium sulfate and dilute sulfuric acid co-solution by using the all-purpose recovery heat pump technology, and sodium sulfate decahydrate is separated out by crystallization circulation and centrifugal separation; meanwhile, after the sodium silicate glass fiber is acid leached, a certain amount of sodium sulfate crystal is left in the fibers, a large amount of hot water needs to be used for circulating cleaning, the all-purpose recovery heat pump unit generates low-temperature refrigerant and a large amount of heat energy is by-produced for heating and warming the cleaning water, steam or electric energy is no longer needed for heating the cleaning water, and a green production process technology of comprehensive energy utilization is realized.

[0086] The green production process technology of the high silica glass fiber is used for crystallizing the sodium sulfate and dilute sulfuric acid co-solution after the sodium silicate glass fiber is reacted with dilute sulfuric acid, heat exchange is carried out between low-temperature refrigerant and the sodium sulfate and dilute sulfuric acid co-solution by using the all-purpose recovery heat pump technology, and sodium sulfate decahydrate is separated out by crystallization circulation and centrifugal separation; meanwhile, after the sodium silicate glass fiber is acid leached, a certain amount of sodium sulfate crystal is left in the fibers, a large amount of hot water needs to be used for circulating cleaning, the all-purpose recovery heat pump unit generates low-temperature refrigerant and a large amount of heat energy is by-produced for heating and warming the cleaning water, steam or electric energy is no longer needed for heating the cleaning water, and a green production process technology of comprehensive energy utilization is realized.

[0087] Finally, it should be noted that the above detailed description is only used to explain the technical solutions of the present application and not to limit the present application. Although the present application has been described in detail with reference to the examples, those skilled in the art should understand that the technical solutions of the present application can be modified and replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application, and all modifications and replacements should be included in the scope of the claims of the present application.

Claims

1. A green process for the production of high silica glass fibers, characterized by: It comprises the following steps: Step one: using sodium-silicon glass fiber as raw material to process sodium-silicon glass fiber semi-finished product; Step two: the sodium-silicon glass fiber semi-finished product in step one is reacted with dilute sulfuric acid in a container according to the acid leaching process, and sodium sulfate is generated; Step three: the sodium sulfate generated in step two is co-dissolved with dilute sulfuric acid solution. With the circulation of the acid leaching process, the concentration of sodium sulfate in the dilute sulfuric acid solution increases to saturation, and sodium sulfate begins to crystallize and is included in the high-silicon glass fiber semi-finished product, which affects the quality of the high-silicon product. If it cannot be used for acid leaching, it needs to be discharged from the sodium sulfate and dilute sulfuric acid solution; Step four: using the low-temperature crystallization characteristics of sodium sulfate, and assisted by a set of process equipment, the sodium sulfate and dilute sulfuric acid solution in step three is cooled by freezing liquid exchange to make sodium sulfate and dilute sulfuric acid solution in the sodium sulfate and dilute sulfuric acid solution crystallize to produce sodium sulfate decahydrate, and then solid-liquid separation is carried out by centrifuge; Step five: the dilute sulfuric acid solution separated by centrifuge in step four is returned to the acid leaching treatment tank and adjusted to the required sulfuric acid concentration for acid leaching treatment of sodium-silicon glass fiber, and the sulfuric acid solution is used for secondary circulation; Step six: the sodium sulfate decahydrate separated by centrifuge in step four is melted, diluted and PH adjusted by hot water, and then transferred to MVR for evaporation crystallization to obtain high-quality anhydrous sodium sulfate; Step seven: the anhydrous sodium sulfate generated in step six is tested and stored as a byproduct, part of which is used for high-silicon raw material production, and the other part is directly sold on the market as a byproduct; Step eight: in step two, the sodium-silicon glass fiber semi-finished product reacts with dilute sulfuric acid of a certain concentration to generate sodium sulfate and high-silicon glass fiber or product semi-finished product. However, due to the generation of inorganic salt crystals during acid leaching treatment, the inorganic salt crystals are left on the surface of the high-silicon or product semi-finished product. Hot water is used to dissolve and clean the inorganic salt crystals left on the surface of the high-silicon or product semi-finished product; Step nine: the hot water used in step eight is controlled above the solubility of sodium sulfate; Step ten: combining the cleaning hot water required in step nine with the low-temperature refrigerant medium required for low-temperature crystallization of sodium sulfate in step four; Step eleven: in step six, the sodium sulfate decahydrate needs to be heated and melted. A hot water coil type atmospheric hot melting tank is used, combined with the melting heat of sodium sulfate decahydrate, and a large amount of hot water generated by the heat pump in step ten is circulated in the hot melting tank coil to melt the sodium sulfate decahydrate in the hot melting tank; Step twelve: the cleaning wastewater generated by dissolving and cleaning the inorganic salt crystals left on the surface of the high-silicon or product semi-finished product in step eight is a low-acid concentration wastewater. This part of low-acid concentration wastewater is neutralized to neutral by on-line PH detection and neutralization adjustment; Step thirteen: the cleaning wastewater adjusted by neutralization in step twelve is physically coarsely filtered and finely filtered to remove a small amount of high-silicon fiber fluff in the cleaning water; Step fourteen: the cleaning water in step thirteen after removing the high-silicon fiber fluff is filtered and desalted by multi-stage reverse osmosis to generate reclaimed water and high-salt concentrated water, and the reclaimed water is used in the cleaning process for dissolving and cleaning the inorganic salt crystals; Step fifteen: the high salt concentration water produced in step fourteen is exchanged with the sodium sulfate and dilute sulfuric acid co-solution in step three by freezing liquid exchange, so that the sodium sulfate in the sodium sulfate and dilute sulfuric acid co-solution is precipitated to produce sodium sulfate decahydrate, and then solid-liquid separation is carried out by a centrifuge.

2. A green process for the production of high silica glass fibers as claimed in claim 1, wherein: The concentration of the dilute sulfuric acid in step two is 8-15%.

3. A green process for the production of high silica glass fibers as claimed in claim 1, wherein: In step four, a set of process equipment uses low-temperature refrigerant-5℃ to support process cooling equipment, controls the temperature of the sodium sulfate and dilute sulfuric acid co-solution at 0-10℃, and then uses the sodium sulfate to crystallize and separate out through a large circulating crystallizer.

4. A green process for the production of high silica glass fibers as claimed in claim 1, wherein: The sodium sulfate and dilute sulfuric acid co-solution in step three is washed by hot water required in step eight, combined with the solubility and temperature attribute relationship of sodium sulfate, and the hot water is controlled at 40-55℃.

5. A green process for the production of high silica glass fibers as claimed in claim 1, wherein: In step five, the dilute sulfuric acid liquid separated from the solid-liquid separation is returned to the acid leaching treatment tank, and the heat exchange of energy recovery and mother liquor precooling is increased. After acid leaching treatment, the effluent is subjected to countercurrent heat exchange between the frozen crystallization liquid and the low-temperature dilute sulfuric acid liquid after low-temperature crystallization.

6. A green process for the production of high silica glass fibers as claimed in claim 1, wherein: In step six, the anhydrous sodium sulfate is combined with the market customer's need for drying and packaging of anhydrous sodium sulfate, and finally inspected and produced as a byproduct into the warehouse.

7. A green process for the production of high silica glass fibers as claimed in claim 1, wherein: In step fourteen, the intermediate water is stored in an intermediate water pool, and hot water for producing intermediate water is generated by a heat pump heat exchanger from the intermediate water pool.