System for preparing white carbon black and co-producing sodium fluoride by using sodium fluosilicate as raw material and use method of system

Abstract

The invention discloses a system for preparing white carbon black and co-producing sodium fluoride by using sodium fluosilicate as a raw material and a use method of the system, and relates to the technical field of white carbon black, in particular to a system for preparing white carbon black and co-producing sodium fluoride by using sodium fluosilicate as a raw material and a use method of the system. On the premise of producing high-quality white carbon black, the method successfully solves the defects of high temperature condition, high equipment requirement and high device price in the conventional fumed silica production, and also solves the problem that the low-cost waste sodium fluosilicate in the phosphate fertilizer industry cannot be efficiently utilized; meanwhile, the invention also provides a new process route and system for continuous production of white carbon black by a precipitation method, provides a new optional way for resource utilization of fluorine and silicon, and has positive significance and effects on improvement of comprehensive utilization of fluorine and silicon resources, environmental protection, benefit improvement, development of more high-added-value products and promotion of fluorine chemical development.

Description

Technical Field

[0001] The invention relates to the technical field of white carbon black, and in particular to a system for preparing white carbon black and co-producing sodium fluoride by taking sodium fluorosilicate as a raw material, and a use method thereof. Background Art

[0002] Phosphate fertilizer is one of the three major single-element fertilizers. In recent years, with the continuous growth of the global population, the demand for meat products and grain has increased, and the steady release of the output and demand of the phosphate fertilizer market has made the production capacity of phosphate fertilizer remain at a high level with slight fluctuations for a long time. According to statistics, in the process of phosphate fertilizer production, every 1 million tons of phosphate fertilizer produced will also produce 50,000 tons of fluosilicic acid byproducts, and the utilization rate of the entire industry in my country (in terms of fluosilicic acid) is less than 40%. Most phosphate fertilizer manufacturers will directly prepare the byproduct fluosilicic acid into sodium fluosilicate during the production process. Sodium fluosilicate is one of the main byproducts in the production of phosphate fertilizer industry. It is rich in fluorine and silicon elements, but it is highly corrosive and toxic. Random discharge will cause certain damage to health and the environment. It is also an inorganic chemical with low added value and poor economic benefits, so its production capacity is often in excess.

[0003] White carbon black is a white fine powder, the main component of which is silicon dioxide. It has good electrical insulation and porosity. It is widely used as a good reinforcing agent for synthetic rubber. Its reinforcing performance is second only to carbon black. If it is super-refined and properly treated, its effect is even better than carbon black. White carbon black can also be used as a blending agent for insulating paint, a matting agent for paint, a thixotropic agent for electronic component encapsulation materials, a precipitant for fluorescent powder when coating fluorescent screens, a filler for color printing plates, and a mold release agent for casting. White carbon black added to resin can improve the moisture resistance and insulation properties of the resin. White carbon black filled in plastic products can increase anti-skid and oil resistance. White carbon black filled in silicone resin can be made into plastics that can withstand temperatures above 200°C. White carbon black is used as a filler and surface component of paper in the papermaking industry. It can also be used in rubber products and various automobile inner and outer tires. Adding a certain amount of white carbon black to ordinary tires can increase the service life of the tires. White carbon black not only has good reinforcing properties, wear resistance, slip resistance and adhesion, but is also a good light-colored reinforcing material. Silica can be used as a filling material for plastics such as polyethylene, polypropylene, polybutene, and epoxy resin, which can improve the elastic strength and wear resistance of plastics as well as the thermal stability of hardness. Silica is mainly divided into fumed silica and precipitated silica based on the production method. Fumed silica products have high purity and large specific surface area, but their further development is limited due to their complex preparation process and high production cost. At present, precipitated silica occupies a dominant position in the silica market. The raw materials used are cheap, and the production process and equipment are simple, but how to continuously produce silica products with excellent performance is still the key to future research.

[0004] Sodium fluoride is a fluoride salt with a wide range of applications. It is the raw material for making most fluorides and is generally in the form of white crystalline powder. Sodium fluoride can be used as an agricultural pesticide and has a bactericidal effect; sodium fluoride added to toothpaste can prevent caries and reduce the formation of dental plaque; sodium fluoride can also be used as an adhesive and preservative in the leather industry. In addition, the application of sodium fluoride also involves many fields such as medical treatment, coatings, papermaking, lithium battery materials and metallurgy.

[0005] Therefore, if we can explore a continuous process equipment and process route for preparing high-purity white carbon black and sodium fluoride using sodium fluorosilicate as raw material, we can not only utilize the fluorine and silicon sources in phosphate fertilizer production to improve their economic value, but also reduce pollution and damage to the environment. Summary of the invention

[0006] The present invention aims to solve the technical problem of overcapacity of sodium fluorosilicate, a byproduct in the current phosphate fertilizer production process, and provides a system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as a raw material and a method for using the system.

[0007] The system for preparing white carbon black and co-producing sodium fluoride by using sodium fluorosilicate as raw material is composed of a sodium fluorosilicate storage tank 1, a first pump 2, a sodium carbonate storage tank 3, a second pump 4, a reactor 5, a precipitation device 6, a cleaning device 7, a washing device 8, a dryer 9, a pulverizer 10, a liquid storage tank 11, an evaporator 12, a filtering device 13, a third pump 14 and a spiral pipeline 15.

[0008] The outlet of the sodium fluorosilicate storage tank 1 and the outlet of the sodium carbonate storage tank 3 are respectively connected to the inlet of the reactor 5, a first pump 2 is arranged between the sodium fluorosilicate storage tank 1 and the reactor 5, and a second pump 4 is arranged between the sodium carbonate storage tank 3 and the reactor 5; the outlet of the reactor 5 is connected to the upper inlet of the precipitation device 6, and the top of the precipitation device 6 is provided with an exhaust pipe 6-2 with a condensing function for discharging the carbon dioxide gas generated in the reaction and condensing the water vapor into liquid to flow back into the precipitation device 6, and the condensing part of the exhaust pipe 6-2 is connected to the external cooling water; the outer wall of the precipitation device 6 is provided with an overflow weir 6-1, the lower outlet of the overflow weir 6-1 is connected to the inlet of the liquid storage tank 11, the bottom outlet of the precipitation device 6 is connected to the top inlet of the cleaning device 7, and the lower part of the side wall of the cleaning device 7 is connected to the external water source; the bottoms of the precipitation device 6 and the cleaning device 7 are both provided with valves; the top of the cleaning device 7 is provided with an outlet The bottom outlet of the cleaning device 7 is connected to the inlet of the washing device 8, the lower part of the side wall of the washing device 8 is connected to the external water source, the bottom outlet of the washing device 8 is connected to the inlet of the dryer 9, the upper and middle outlets of the washing device 8 are connected to the inlet of the liquid storage tank 11, and the outlet of the dryer 9 is connected to the inlet of the pulverizer 10; the bottom outlet of the liquid storage tank 11 is connected to the inlet of the evaporator 12, the bottom outlet of the evaporator 12 is connected to the inlet of the filter device 13, and the filtrate outlet of the filter device 13 is connected to the inlet of the sodium carbonate storage tank 3; the top outlet of the evaporator 12 is connected to the inlet of the spiral pipe 15, the outlet of the spiral pipe 15 is connected to the inlet of the third pump 14, and the outlet of the third pump 14 is connected to the lower part of the side wall of the cleaning device 7, and the spiral pipe 15 is vertically arranged in the sodium carbonate storage tank 3, the inlet of the spiral pipe 15 is at the bottom, and the outlet of the spiral pipe 15 is at the top.

[0009] The method of using the system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as a raw material of the present invention is as follows:

[0010] 1. Mix sodium fluorosilicate with water and heat it to increase the solubility of sodium fluorosilicate in water, and then transfer it to a sodium fluorosilicate storage tank 1; transfer a sodium carbonate aqueous solution prepared according to a specific molar ratio of sodium fluorosilicate and sodium carbonate to a sodium carbonate storage tank 3;

[0011] 2. Pumping the sodium fluorosilicate aqueous solution and the sodium carbonate aqueous solution into the reactor 5 by the first pump 2 and the second pump 4 respectively for mixing, heating the reactor 5, and the sodium fluorosilicate and the sodium carbonate react to generate SiO2·nH2O and sodium fluoride, and the sodium fluoride is dissolved in the hot solution and is carried into the precipitation device 6 together with the SiO2·nH2O along with the water flow;

[0012] 3. After entering the precipitation device 6, SiO2·nH2O naturally settles to the bottom of the container, which is controlled by a valve. The valve is opened to allow SiO2·nH2O and a small amount of orthosilicic acid solution to enter the cleaning device 7. The supernatant of the precipitation device 6 is discharged into the liquid storage tank 11 through the overflow weir 6-1;

[0013] Fourth, the lower part of the side wall of the cleaning device 7 is connected to an external water source, and the water flow rate is controlled to be 20L / h-30L / h so that it does not affect the sedimentation process of SiO2·nH2O. At the same time, the orthosilicic acid can be taken out of the device from the top outlet of the cleaning device 7 with the water flow and discharged into the liquid storage tank 11. The liquid in the liquid storage tank 11 is discharged into the evaporation device 12. SiO2·nH2O is precipitated at the bottom of the cleaning device 7. The valve is opened to discharge SiO2·nH2O into the washing device 8. The lower part of the side wall of the washing device 8 is connected to an external water source. After being washed again, SiO2·nH2O enters the dryer 9 for drying, and then enters the pulverizer 10 for pulverization to obtain a white carbon black product;

[0014] 5. High-temperature evaporation is performed in the evaporation device 12 to precipitate sodium fluoride crystals. The top outlet of the evaporation device 12 is used to discharge water vapor. The water vapor is cooled into liquid through the spiral pipe 15 in the sodium carbonate storage tank 3 for heat exchange and then connected to the cleaning device 7 to play a role in cleaning the cleaning device 7. At this time, the external water source is turned off; the heat exchange process of the spiral pipe 15 can also heat the sodium carbonate solution; the remaining sodium carbonate solution, orthosilicic acid solution and sodium fluoride in the evaporation device 12 are transferred to the filter device 13 through the bottom outlet for filtration. The filter device 13 is used to filter and recover the sodium fluoride solid product, and the remaining filtrate is returned to the sodium carbonate storage tank 3 for recycling.

[0015] The specific surface area of ​​the white carbon black recovered in step 4 of the present invention is not less than 315 m 2 / g.

[0016] The present invention provides a production process method and system for preparing high-quality white carbon black and co-producing sodium fluoride using sodium fluorosilicate, a waste material in phosphate fertilizer production, as a raw material. Under the premise of producing high-quality white carbon black, the present invention successfully solves the disadvantages of high temperature conditions, high equipment requirements, and expensive equipment in conventional gas-phase white carbon black production, and also solves the problem that low-cost waste sodium fluorosilicate in the phosphate fertilizer industry cannot be efficiently utilized. At the same time, it also provides a new process route and system for continuous production of precipitation-processed white carbon black, providing a new optional way for the utilization of fluorine and silicon resources, and has positive significance and role in improving the comprehensive utilization of fluorine and silicon resources, protecting the environment, improving benefits, developing more high-value-added products, and promoting the development of fluorine chemical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1This is a schematic diagram of a system for preparing white carbon black using sodium fluorosilicate as a raw material and co-producing sodium fluoride in a specific implementation mode 1. DETAILED DESCRIPTION

[0018] Specific implementation method 1: This implementation method is a system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as raw material, such as Figure 1 As shown, it is specifically composed of a sodium fluorosilicate storage tank 1, a first pump 2, a sodium carbonate storage tank 3, a second pump 4, a reactor 5, a precipitation device 6, a cleaning device 7, a washing device 8, a dryer 9, a pulverizer 10, a liquid storage tank 11, an evaporator 12, a filtering device 13, a third pump 14 and a spiral pipeline 15;

[0019] The outlet of the sodium fluorosilicate storage tank 1 and the outlet of the sodium carbonate storage tank 3 are respectively connected to the inlet of the reactor 5, a first pump 2 is arranged between the sodium fluorosilicate storage tank 1 and the reactor 5, and a second pump 4 is arranged between the sodium carbonate storage tank 3 and the reactor 5; the outlet of the reactor 5 is connected to the upper inlet of the precipitation device 6, and the top of the precipitation device 6 is provided with an exhaust pipe 6-2 with a condensing function for discharging the carbon dioxide gas generated in the reaction and condensing the water vapor into liquid to flow back into the precipitation device 6, and the condensing part of the exhaust pipe 6-2 is connected to the external cooling water; the outer wall of the precipitation device 6 is provided with an overflow weir 6-1, the lower outlet of the overflow weir 6-1 is connected to the inlet of the liquid storage tank 11, the bottom outlet of the precipitation device 6 is connected to the top inlet of the cleaning device 7, and the lower part of the side wall of the cleaning device 7 is connected to the external water source; the bottoms of the precipitation device 6 and the cleaning device 7 are both provided with valves; the top of the cleaning device 7 is provided with an outlet The bottom outlet of the cleaning device 7 is connected to the inlet of the washing device 8, the lower part of the side wall of the washing device 8 is connected to the external water source, the bottom outlet of the washing device 8 is connected to the inlet of the dryer 9, the upper and middle outlets of the washing device 8 are connected to the inlet of the liquid storage tank 11, and the outlet of the dryer 9 is connected to the inlet of the pulverizer 10; the bottom outlet of the liquid storage tank 11 is connected to the inlet of the evaporator 12, the bottom outlet of the evaporator 12 is connected to the inlet of the filter device 13, and the filtrate outlet of the filter device 13 is connected to the inlet of the sodium carbonate storage tank 3; the top outlet of the evaporator 12 is connected to the inlet of the spiral pipe 15, the outlet of the spiral pipe 15 is connected to the inlet of the third pump 14, and the outlet of the third pump 14 is connected to the lower part of the side wall of the cleaning device 7, and the spiral pipe 15 is vertically arranged in the sodium carbonate storage tank 3, the inlet of the spiral pipe 15 is at the bottom, and the outlet of the spiral pipe 15 is at the top.

[0020] Specific embodiment 2: This embodiment is different from the specific embodiment 1 in that the bottom of the precipitation device 6 and the cleaning device 7 are both provided with electromagnetic valves. The rest is the same as the specific embodiment 1.

[0021] Specific embodiment 3: This embodiment is different from specific embodiment 1 or 2 in that: a heating wire is provided on the reactor 5. The rest is the same as specific embodiment 1 or 2.

[0022] Specific embodiment 4: This embodiment is a method for using the system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as raw material in specific embodiment 1, and the specific process is as follows:

[0023] 1. Mix sodium fluorosilicate with water and heat it to increase the solubility of sodium fluorosilicate in water, and then transfer it to a sodium fluorosilicate storage tank 1; transfer a sodium carbonate aqueous solution prepared according to a specific molar ratio of sodium fluorosilicate and sodium carbonate to a sodium carbonate storage tank 3;

[0024] 2. Pumping the sodium fluorosilicate aqueous solution and the sodium carbonate aqueous solution into the reactor 5 by the first pump 2 and the second pump 4 respectively for mixing, heating the reactor 5, and the sodium fluorosilicate and the sodium carbonate react to generate SiO2·nH2O and sodium fluoride, and the sodium fluoride is dissolved in the hot solution and is carried into the precipitation device 6 together with the SiO2·nH2O along with the water flow;

[0025] 3. After entering the precipitation device 6, SiO2·nH2O naturally settles to the bottom of the container, which is controlled by a valve. The valve is opened to allow SiO2·nH2O and a small amount of orthosilicic acid solution to enter the cleaning device 7. The supernatant of the precipitation device 6 is discharged into the liquid storage tank 11 through the overflow weir 6-1;

[0026] Fourth, the lower part of the side wall of the cleaning device 7 is connected to an external water source, and the water flow rate is controlled to be 20L / h-30L / h so that it does not affect the sedimentation process of SiO2·nH2O. At the same time, the orthosilicic acid can be taken out of the device from the top outlet of the cleaning device 7 with the water flow and discharged into the liquid storage tank 11. The liquid in the liquid storage tank 11 is discharged into the evaporation device 12. SiO2·nH2O is precipitated at the bottom of the cleaning device 7. The valve is opened to discharge SiO2·nH2O into the washing device 8. The lower part of the side wall of the washing device 8 is connected to an external water source. After being washed again, SiO2·nH2O enters the dryer 9 for drying, and then enters the pulverizer 10 for pulverization to obtain a white carbon black product;

[0027] 5. High-temperature evaporation is performed in the evaporation device 12 to precipitate sodium fluoride crystals. The top outlet of the evaporation device 12 is used to discharge water vapor. The water vapor is cooled into liquid through the spiral pipe 15 in the sodium carbonate storage tank 3 for heat exchange and then connected to the cleaning device 7 to play a role in cleaning the cleaning device 7. At this time, the external water source is turned off; the heat exchange process of the spiral pipe 15 can also heat the sodium carbonate solution; the remaining sodium carbonate solution, orthosilicic acid solution and sodium fluoride in the evaporation device 12 are transferred to the filter device 13 through the bottom outlet for filtration. The filter device 13 is used to filter and recover the sodium fluoride solid product, and the remaining filtrate is returned to the sodium carbonate storage tank 3 for recycling.

[0028] Specific embodiment 5: This embodiment is different from specific embodiment 4 in that in step 1, sodium fluorosilicate is mixed with water, heated to 75° C. and stirred, the stirring speed is 100 r / min to 200 r / min, the stirring time is 10 min to 20 min, and then transferred to the sodium fluorosilicate storage tank 1. Others are the same as specific embodiment 4.

[0029] Specific implementation method 6: This implementation method is different from specific implementation method 5 in that the mass fraction of the sodium carbonate aqueous solution in step 1 is 30%. Other aspects are the same as those of specific implementation method 5.

[0030] Specific embodiment 7: This embodiment is different from specific embodiment 6 in that the flow rate of the sodium fluorosilicate aqueous solution and the sodium carbonate aqueous solution pumped into the reactor 5 in step 2 is 13L / h to 16L / h. Other aspects are the same as specific embodiment 6.

[0031] Specific embodiment eight: This embodiment differs from specific embodiment seven in that in step two, the molar ratio of sodium fluorosilicate to sodium carbonate in reactor 5 is 1:(3-4). Other aspects are the same as specific embodiment seven.

[0032] Specific embodiment 9: This embodiment is different from specific embodiment 8 in that: the heating temperature of the reactor 5 in step 2 is 65° C. to 80° C.; the drying temperature of the dryer 9 in step 4 is 120° C. The rest is the same as specific embodiment 8.

[0033] Specific embodiment 10: This embodiment is different from specific embodiment 9 in that the bottom valves of the precipitation device 6 in step 3 and the cleaning device 7 in step 4 are both in the open state for 1s to 2s and in the closed state for 1min to 2min, so that SiO2·nH2O is precipitated and discharged. The rest is the same as specific embodiment 9.

[0034] The present invention is verified by the following tests:

[0035] Test 1: This test is a system for preparing white carbon black with sodium fluorosilicate as raw material and co-producing sodium fluoride. Figure 1 As shown, it is specifically composed of a sodium fluorosilicate storage tank 1, a first pump 2, a sodium carbonate storage tank 3, a second pump 4, a reactor 5, a precipitation device 6, a cleaning device 7, a washing device 8, a dryer 9, a pulverizer 10, a liquid storage tank 11, an evaporator 12, a filtering device 13, a third pump 14 and a spiral pipe 15; the reactor 5 is provided with an electric heating wire;

[0036] The outlet of the sodium fluorosilicate storage tank 1 and the outlet of the sodium carbonate storage tank 3 are respectively connected to the inlet of the reactor 5, a first pump 2 is arranged between the sodium fluorosilicate storage tank 1 and the reactor 5, and a second pump 4 is arranged between the sodium carbonate storage tank 3 and the reactor 5; the outlet of the reactor 5 is connected to the upper inlet of the precipitation device 6, and the top of the precipitation device 6 is provided with an exhaust pipe 6-2 with a condensing function for discharging the carbon dioxide gas generated in the reaction and condensing the water vapor into liquid to flow back into the precipitation device 6, and the condensing part of the exhaust pipe 6-2 is connected to the external cooling water; the outer wall of the precipitation device 6 is provided with an overflow weir 6-1, the lower outlet of the overflow weir 6-1 is connected to the inlet of the liquid storage tank 11, the bottom outlet of the precipitation device 6 is connected to the top inlet of the cleaning device 7, and the lower part of the side wall of the cleaning device 7 is connected to the external water source; the bottom of the precipitation device 6 and the cleaning device 7 are both provided with solenoid valves; the top of the cleaning device 7 is provided with an outlet The bottom outlet of the cleaning device 7 is connected to the inlet of the washing device 8, the lower part of the side wall of the washing device 8 is connected to the external water source, the bottom outlet of the washing device 8 is connected to the inlet of the dryer 9, the upper and middle outlets of the washing device 8 are connected to the inlet of the liquid storage tank 11, and the outlet of the dryer 9 is connected to the inlet of the pulverizer 10; the bottom outlet of the liquid storage tank 11 is connected to the inlet of the evaporator 12, the bottom outlet of the evaporator 12 is connected to the inlet of the filter device 13, and the filtrate outlet of the filter device 13 is connected to the inlet of the sodium carbonate storage tank 3; the top outlet of the evaporator 12 is connected to the inlet of the spiral pipe 15, the outlet of the spiral pipe 15 is connected to the inlet of the third pump 14, and the outlet of the third pump 14 is connected to the lower part of the side wall of the cleaning device 7, and the spiral pipe 15 is vertically arranged in the sodium carbonate storage tank 3, the inlet of the spiral pipe 15 is at the bottom, and the outlet of the spiral pipe 15 is at the top.

[0037] Experiment 2: This experiment is a method for using the system in Experiment 1 to prepare white carbon black using sodium fluorosilicate as raw material and co-produce sodium fluoride. The specific process is as follows:

[0038] 1. Mix sodium fluorosilicate and water, heat to 75°C and stir at a stirring speed of 100r / min to 200r / min for 10min to 20min, and then transfer to a sodium fluorosilicate storage tank 1; transfer a sodium carbonate aqueous solution prepared according to a specific molar ratio of sodium fluorosilicate and sodium carbonate to a sodium carbonate storage tank 3; the sodium fluorosilicate is a waste sodium fluorosilicate in the phosphate fertilizer industry; the mass fraction of the sodium carbonate aqueous solution is 30%;

[0039] 2. Pumping the sodium fluorosilicate aqueous solution and the sodium carbonate aqueous solution into the reactor 5 through the first pump 2 and the second pump 4 respectively for mixing, heating the reactor 5 to 70° C., the sodium fluorosilicate and the sodium carbonate react to generate SiO2·nH2O and sodium fluoride, the sodium fluoride is dissolved in the hot solution, and is brought into the precipitation device 6 together with the SiO2·nH2O along with the water flow; the flow rate of the sodium fluorosilicate aqueous solution and the sodium carbonate aqueous solution pumped into the reactor 5 is 15 L / h; the molar ratio of sodium fluorosilicate to sodium carbonate in the reactor 5 is 1:3;

[0040] 3. After entering the precipitation device 6, SiO2·nH2O naturally settles to the bottom of the container. The bottom is controlled by a valve. The bottom valve is in an open state for 1s to 2s and in a closed state for 1min to 2min, so that SiO2·nH2O and a small amount of orthosilicic acid solution enter the cleaning device 7. The supernatant of the precipitation device 6 is discharged into the liquid storage tank 11 through the overflow weir 6-1;

[0041] Fourth, the lower part of the side wall of the cleaning device 7 is connected to an external water source, and the water flow rate is controlled to be 25L / h so that it does not affect the sedimentation process of SiO2·nH2O. At the same time, the orthosilicic acid can be taken out of the device from the top outlet of the cleaning device 7 with the water flow and discharged into the liquid storage tank 11. The liquid in the liquid storage tank 11 is discharged into the evaporation device 12. SiO2·nH2O is precipitated at the bottom of the cleaning device 7. The valve at the bottom of the cleaning device 7 is in an open state for 1s and in a closed state for 2min, so that the SiO2·nH2O precipitate is discharged into the washing device 8. The lower part of the side wall of the washing device 8 is connected to an external water source, and the water flow rate is 25L / h. After being washed again, SiO2·nH2O enters the dryer 9 for drying, and the drying temperature is 120°C, and then enters the pulverizer 10 for pulverization to obtain a white carbon black product;

[0042] 5. High-temperature evaporation is performed in the evaporation device 12 to precipitate sodium fluoride crystals. The top outlet of the evaporation device 12 is used to discharge water vapor. The water vapor is cooled into liquid through the spiral pipe 15 in the sodium carbonate storage tank 3 for heat exchange and then connected to the cleaning device 7 to play a role in cleaning the cleaning device 7. At this time, the external water source is turned off; the heat exchange process of the spiral pipe 15 can also heat the sodium carbonate solution; the remaining sodium carbonate solution, orthosilicic acid solution and sodium fluoride in the evaporation device 12 are transferred to the filter device 13 through the bottom outlet for filtration. The filter device 13 is used to filter and recover the sodium fluoride solid product, and the remaining filtrate is returned to the sodium carbonate storage tank 3 for recycling.

[0043] Product physical property testing standards: The testing standards and methods in HG / T 3061-2020 "Chemical Industry Standard of the People's Republic of China - Rubber Compounding - Precipitated Hydrated Silica" are used to determine the physical property parameters of white carbon black. The main test contents include the determination of silicon dioxide content in dry samples, the determination of 45μm sieve residue, the determination of heating loss, the determination of ignition loss of dry samples, and the determination of pH value of water suspension. White carbon black can be divided into six categories according to the size of the nitrogen adsorption specific surface area, as shown in Table 1:

[0044] Table 1 Classification of white carbon black

[0045] category <![CDATA[Nitrogen adsorption specific surface area, m 2 / g]]> category <![CDATA[Nitrogen adsorption specific surface area, m 2 / g]]> A ≥191 D 106～135 B 161～190 E 71～105 C 136～160 F ≤71

[0046] According to industry standards, sodium fluoride is divided into three grades according to its chemical composition, as shown in Table 2:

[0047] Table 2 Classification of sodium fluoride

[0048]

[0049] The results of the physical property parameters of the white carbon black and sodium fluoride prepared in Experiment 2 are as follows:

[0050] Table 3 Physical properties of white carbon black

[0051] Serial number Test items index result Detection Methods 1 Silicon dioxide content (burning product), % 95～98 96.8 HG / T 3062 2 <![CDATA[Specific surface area, m 2 / g]]> Class A≥191 317 GB / T 10722 3 Loss on ignition (dry product), % ≤7.0 2.34 HG / T 3066 4 Heating loss, % 4.0～8.0 4.67 HG / T 3065 5 45μm sieve residue, % ≤0.5 0.01 HG / T 3064 6 <![CDATA[Oil absorption value, 10 -5 m 3 ·kg -1 > 200～350 220 HG / T 3072 7 pH 5.0～8.0 7.3 HG / T 3067

[0052] From the results in Table 3 above, it can be seen that the specific surface area of ​​the white carbon black prepared in Experiment 2 is 317 m 2 / g, which meets the requirements of Class A white carbon black specified in HG / T3061-2020.

[0053] Table 4 Physical properties of sodium fluoride

[0054] Serial number Test items First level indicator result Detection Methods 1 Sodium fluoride content, % ≥98 98.4 YS / T 535.2-2009 2 Silicon dioxide content, % ≤0.5 0.2 YS / T 535.3-2009 3 Carbonate content, % ≤0.37 0.3 YS / T 535.6-2009 4 Soluble sulfate content, % ≤0.3 0.15 YS / T 535.5-2009 5 acidity,% ≤0.1 0.05 YS / T 535.7-2009 6 Water insoluble content, % ≤0.7 0.4 YS / T 535.8-2009 7 Wet water content, % ≤0.5 0.4 YS / T 535.1-2009 8 Sodium fluorosilicate content, % - 0.1 YS / T 535.11-2020

[0055] From the data in Table 4, it can be seen that the sodium fluoride product prepared in Experiment 2 meets the chemical composition requirements of a first-class sodium fluoride product.

[0056] Experiment 3: This experiment is different from Experiment 2 in that:

[0057] In step 2, the molar ratio of sodium fluorosilicate to sodium carbonate in reactor 5 is 1:3.5;

[0058] In step 2, the reactor 5 is heated to 80° C.;

[0059] In step 2, the flow rate of the sodium fluorosilicate aqueous solution and the sodium carbonate aqueous solution pumped into the reactor 5 is 13 L / h. Others are the same as those in experiment 2.

Claims

1. A system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as raw material, characterized in that The system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as raw material comprises a sodium fluorosilicate storage tank (1), a first pump (2), a sodium carbonate storage tank (3), a second pump (4), a reactor (5), a precipitation device (6), a cleaning device (7), a washing device (8), a dryer (9), a pulverizer (10), a liquid storage tank (11), an evaporator (12), a filtering device (13), a third pump (14) and a spiral pipeline (15); The outlet of the sodium fluorosilicate storage tank (1) and the outlet of the sodium carbonate storage tank (3) are respectively connected to the inlet of the reactor (5); a first pump (2) is arranged between the sodium fluorosilicate storage tank (1) and the reactor (5); a second pump (4) is arranged between the sodium carbonate storage tank (3) and the reactor (5); the outlet of the reactor (5) is connected to the upper inlet of the precipitation device (6); a condensing exhaust pipe (6-2) is arranged on the top of the precipitation device (6) for discharging the carbon dioxide gas generated in the reaction and condensing the water vapor into liquid The liquid body flows back to the precipitation device (6), and the condensation part of the exhaust pipe (6-2) is connected to the external cooling water; the outer wall of the precipitation device (6) is provided with an overflow weir (6-1), the lower outlet of the overflow weir (6-1) is connected to the inlet of the liquid storage tank (11), the bottom outlet of the precipitation device (6) is connected to the top inlet of the cleaning device (7), and the lower part of the side wall of the cleaning device (7) is connected to the external water source; the bottom of the precipitation device (6) and the cleaning device (7) are both provided with valves; the top of the cleaning device (7) is provided with an outlet connected to the The inlet of the liquid storage tank (11) is connected; the bottom outlet of the cleaning device (7) is connected to the inlet of the washing device (8), the lower part of the side wall of the washing device (8) is connected to an external water source, the bottom outlet of the washing device (8) is connected to the inlet of the dryer (9), the middle and upper outlet of the washing device (8) is connected to the inlet of the liquid storage tank (11), and the outlet of the dryer (9) is connected to the inlet of the pulverizer (10); the bottom outlet of the liquid storage tank (11) is connected to the inlet of the evaporator (12), and the bottom outlet of the evaporator (12) is connected to the inlet of the pulverizer (10). The evaporator (12) is connected to the inlet of the filter device (13), and the filtrate outlet of the filter device (13) is connected to the inlet of the sodium carbonate storage tank (3); the top outlet of the evaporator (12) is connected to the inlet of the spiral pipe (15), and the outlet of the spiral pipe (15) is connected to the inlet of the third pump (14), and the outlet of the third pump (14) is connected to the lower part of the side wall of the cleaning device (7), and the spiral pipe (15) is vertically arranged in the sodium carbonate storage tank (3), with the inlet of the spiral pipe (15) at the bottom and the outlet of the spiral pipe (15) at the top.

2. A system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as raw material according to claim 1, characterized in that The bottoms of the precipitation device (6) and the cleaning device (7) are both provided with electromagnetic valves.

3. A system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as raw material according to claim 1, characterized in that The reactor (5) is provided with a heating wire.

4. The method for using a system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as a raw material as claimed in claim 1, characterized in that The process of using the system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as raw material is as follows:

1. Mixing sodium fluorosilicate with water and heating it to increase the solubility of sodium fluorosilicate in water, and then transferring it to a sodium fluorosilicate storage tank (1); transferring a sodium carbonate aqueous solution prepared according to a specific molar ratio of sodium fluorosilicate and sodium carbonate to a sodium carbonate storage tank (3); 2. Pumping the sodium fluorosilicate aqueous solution and the sodium carbonate aqueous solution into the reactor (5) by means of the first pump (2) and the second pump (4) respectively for mixing, heating the reactor (5), causing the sodium fluorosilicate and the sodium carbonate to react to generate SiO2·nH2O and sodium fluoride, wherein the sodium fluoride is dissolved in the hot solution and is carried into the precipitation device (6) together with the SiO2·nH2O along with the water flow; 3. After entering the precipitation device (6), SiO2·nH2O naturally settles to the bottom of the container. The bottom is controlled by a valve. The valve is opened to allow SiO2·nH2O and a small amount of orthosilicic acid solution to enter the cleaning device (7). The supernatant of the precipitation device (6) is discharged into the liquid storage tank (11) through the overflow weir (6-1); Fourth, the lower part of the side wall of the cleaning device (7) is connected to an external water source, and the water flow rate is controlled to be 20L / h to 30L / h so that it does not affect the sedimentation process of SiO2·nH2O. At the same time, the orthosilicic acid can be carried out of the device from the top outlet of the cleaning device (7) with the water flow and discharged into the liquid storage tank (11). The liquid in the liquid storage tank (11) is discharged into the evaporation device (12). SiO2·nH2O is precipitated at the bottom of the cleaning device (7). The valve is opened to discharge SiO2·nH2O into the washing device (8). The lower part of the side wall of the washing device (8) is connected to an external water source. After being washed again, SiO2·nH2O enters the dryer (9) for drying, and then enters the pulverizer (10) for pulverization to obtain a white carbon black product; Fifth, high-temperature evaporation is performed in the evaporation device (12) to precipitate sodium fluoride crystals. The top outlet of the evaporation device (12) is used to discharge water vapor. The water vapor is cooled into liquid through the spiral pipe (15) in the sodium carbonate storage tank (3) for heat exchange and then connected to the cleaning device (7) to play a role in cleaning the cleaning device (7). At this time, the external water source is closed; the heat exchange process of the spiral pipe (15) can also heat the sodium carbonate solution; the remaining sodium carbonate solution, orthosilicic acid solution and sodium fluoride in the evaporation device (12) are transferred to the filtering device (13) through the bottom outlet for filtration. The filtering device (13) is used to filter and recover the sodium fluoride solid product, and the remaining filtrate is returned to the sodium carbonate storage tank (3) for recycling.

5. The method for using a system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as raw material according to claim 4, characterized in that In step 1, sodium fluorosilicate is mixed with water, heated to 75° C. and stirred at a stirring speed of 100 r / min to 200 r / min for 10 min to 20 min, and then transferred to a sodium fluorosilicate storage tank (1).

6. The method for using a system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as raw material according to claim 4, characterized in that The mass fraction of the sodium carbonate aqueous solution described in step 1 is 30%.

7. The method for using a system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as raw material according to claim 4, characterized in that In step 2, the flow rate of the sodium fluorosilicate aqueous solution and the sodium carbonate aqueous solution pumped into the reactor (5) is 13 L / h to 16 L / h.

8. The method for using a system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as raw material according to claim 4, characterized in that In step 2, the molar ratio of sodium fluorosilicate to sodium carbonate in the reactor (5) is 1:(3-4).

9. The method for using a system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as raw material according to claim 4, characterized in that The heating temperature of the reactor (5) in step 2 is 65°C to 80°C; the drying temperature of the dryer (9) in step 4 is 120°C.

10. The method for using a system for preparing white carbon black and co-producing sodium fluoride using sodium fluorosilicate as raw material according to claim 4, characterized in that The bottom valves of the precipitation device (6) in step 3 and the cleaning device (7) in step 4 are both in the open state for 1 second to 2 seconds and in the closed state for 1 minute to 2 minutes, thereby discharging the SiO2·nH2O precipitate.

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