A system for preparing white carbon black and co-producing sodium fluoride by using sodium fluosilicate as raw material and a method for using the system

Abstract

The application relates to a system for preparing white carbon black and co-producing sodium fluoride by using sodium fluosilicate as raw material and a use method thereof, relates to the technical field of white carbon black, and particularly relates to a system for preparing white carbon black and co-producing sodium fluoride by using sodium fluosilicate as raw material and a use method thereof. The application successfully solves the disadvantages of high-temperature conditions, high requirements for equipment and high device prices in conventional gas-phase white carbon black production under the premise of outputting high-quality white carbon black, solves the problem that low-cost waste sodium fluosilicate cannot be efficiently utilized in the phosphate fertilizer industry, simultaneously provides a new process route and system for continuous production of white carbon black by using the precipitation method, provides a new optional way for resource utilization of fluorine and silicon, has positive significance and role for improving 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.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of white carbon black, and particularly relates to a system for preparing white carbon black from sodium fluosilicate as raw material and co-producing sodium fluoride and a use method thereof. BACKGROUND

[0002] Phosphorus fertilizer is one of the three single-element fertilizers. In recent years, with the continuous growth of global population, the demand for meat products and food increases, and the stable release of phosphorus fertilizer market output and demand makes the production capacity of phosphorus fertilizer be in a high level and slight fluctuation state for a long time. According to statistics, in the production process of phosphorus fertilizer, 50,000 tons of fluosilicic acid by-product will be produced simultaneously for every 1 million tons of phosphorus fertilizer, and the utilization rate (calculated by fluosilicic acid) of the entire industry in China is less than 40%. Most phosphorus fertilizer manufacturers will directly prepare fluosilicic acid into sodium fluosilicate in the production process. Sodium fluosilicate is one of the main by-products in the production of phosphorus fertilizer industry, which has rich fluorine and silicon elements, but it is highly corrosive and has strong toxicity. Random discharge will cause certain damage to the health and environment, and it is an inorganic chemical with low added value and poor economic benefit, so its production capacity is often surplus.

[0003] White carbon black is a white fine powder, the main component of which is silicon dioxide, and it has good electrical insulation and porosity. It is widely used as a good reinforcing agent for synthetic rubber, and its reinforcing performance is only second to carbon black. If it is ultra-refined and properly treated, its effect is even better than that of carbon black. White carbon black can also be used as a blending agent for insulating paint, a gloss reducer for paint, a thixotropic agent for electronic component encapsulation materials, a precipitating agent for fluorescent powder when coating a fluorescent screen, a filling agent for color printing rubber plate, and a demolding agent for casting. Adding white carbon black to resin can improve the moisture resistance and insulation performance of the resin. Filling white carbon black in plastic products can increase the slip resistance and oil resistance. Filling white carbon black into silicone resin can make plastic that can withstand more than 200 DEG C. White carbon black is used as a filler and surface component in the paper industry, and 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 improve the service life of the tires. White carbon black not only has good reinforcing performance, wear resistance, slip resistance and adhesion, but also is a good light-colored reinforcing material. Silicon dioxide can be used as a filling material for plastics such as polyethylene, polypropylene, polybutylene and epoxy resin, which can improve the elastic strength, wear resistance and hardness thermal stability of the plastics. White carbon black is mainly divided into fumed white carbon black and precipitated white carbon black according to the production method. Fumed white carbon black has high purity and large specific surface area, but its preparation process is complex and the production cost is high, which limits its further development. At present, precipitated white carbon black dominates the white carbon black market, and the raw material used is low in price, and the production process and equipment are simple, but how to continuously produce white carbon black products with excellent performance is still the key to future research.

[0004] Sodium fluoride is a kind of fluoride salt with wide application range, and is a raw material for manufacturing most fluorides. In general, sodium fluoride is white crystalline powder. Sodium fluoride can be used as agricultural insecticide and has bactericidal effect. Sodium fluoride added in toothpaste can prevent dental caries and reduce the generation of dental plaque. Sodium fluoride can also be used as adhesive and preservative in leather industry. In addition, the application of sodium fluoride involves medical treatment, paint, papermaking, lithium battery material and metallurgy.

[0005] Therefore, if a continuous process equipment and process route for preparing high-purity white carbon black and sodium fluoride from sodium fluosilicate can be explored, not only the fluorine source and silicon source in the production of phosphate fertilizer can be utilized to improve their economic value, but also the pollution and damage to the environment can be reduced. SUMMARY

[0006] The present application aims to solve the technical problem of overcapacity of by-product sodium fluosilicate in the current production process of phosphate fertilizer, and provides a system for preparing white carbon black from sodium fluosilicate and co-producing sodium fluoride and a use method thereof.

[0007] The system for preparing white carbon black from sodium fluosilicate and co-producing sodium fluoride according to the present application is composed of a sodium fluosilicate 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 fluosilicate storage tank 1 and the outlet of the sodium carbonate storage tank 3 are communicated with the inlet of the reactor 5, a first pump 2 is arranged between the sodium fluosilicate 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 communicated with the upper inlet of the precipitation device 6, a gas exhaust pipe 6-2 with condensing function is arranged at the top of the precipitation device 6 and used for exhausting carbon dioxide gas generated in the reaction and condensing water vapor into liquid to flow back to the precipitation device 6, and the condensing part of the gas exhaust pipe 6-2 is connected with external cooling water; an overflow weir 6-1 is arranged on the outer wall of the precipitation device 6, the lower outlet of the overflow weir 6-1 is communicated with the inlet of the liquid storage tank 11, the bottom outlet of the precipitation device 6 is communicated with the top inlet of the cleaning device 7, and the lower part of the side wall of the cleaning device 7 is communicated with an external water source; the bottom of the precipitation device 6 and the bottom of the cleaning device 7 are both provided with valves; the top of the cleaning device 7 is provided with an outlet communicated with the inlet of the liquid storage tank 11; the bottom outlet of the cleaning device 7 is communicated with the inlet of the washing device 8, the lower part of the side wall of the washing device 8 is communicated with an external water source, the bottom outlet of the washing device 8 is communicated with the inlet of the dryer 9, the middle and upper outlet of the washing device 8 is communicated with the inlet of the liquid storage tank 11, and the outlet of the dryer 9 is communicated with the inlet of the pulverizer 10; the bottom outlet of the liquid storage tank 11 is communicated with the inlet of the evaporator 12, the bottom outlet of the evaporator 12 is communicated with the inlet of the filtering device 13, and the filtrate outlet of the filtering device 13 is communicated with the inlet of the sodium carbonate storage tank 3; the top outlet of the evaporator 12 is communicated with the inlet of the spiral pipe 15, the outlet of the spiral pipe 15 is communicated with the inlet of the third pump 14, the outlet of the third pump 14 is communicated with 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 lower part, and the outlet of the spiral pipe 15 is at the upper part.

[0009] The use method of the system for preparing white carbon black from sodium fluosilicate and co-producing sodium fluoride is as follows:

[0010] I. The sodium fluosilicate is mixed with water and heated to increase the solubility of the sodium fluosilicate in the water, and then is transferred to the sodium fluosilicate storage tank 1; the sodium carbonate aqueous solution prepared according to the specific molar ratio of sodium fluosilicate and sodium carbonate is transferred to the sodium carbonate storage tank 3;

[0011] II. The sodium fluosilicate aqueous solution and the sodium carbonate aqueous solution are respectively pumped into the reactor 5 by the first pump 2 and the second pump 4 for mixing, the reactor 5 is heated, the sodium fluosilicate and the sodium carbonate react to generate SiO2·nH2O and sodium fluoride, the sodium fluoride is dissolved in the hot solution and is taken into the precipitation device 6 together with the SiO2·nH2O and water;

[0012] III. 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 make SiO2·nH2O and a small amount of orthosilicic acid solution enter the cleaning device 7, the supernatant of the precipitation device 6 is discharged to the storage tank 11 through the overflow weir 6-1;

[0013] IV. The lower part of the side wall of the cleaning device 7 is connected with an external water source, the water flow rate is controlled to be 20L / h-30L / h so as not to affect the settling process of SiO2·nH2O and at the same time can make orthosilicic acid be taken out of the device from the top outlet of the cleaning device 7 and discharged into the storage tank 11, the liquid in the storage tank 11 is discharged into the evaporation device 12, SiO2·nH2O settles at the bottom of the cleaning device 7, the valve is opened to discharge SiO2·nH2O to the washing device 8, the lower part of the side wall of the washing device 8 is connected with an external water source, SiO2·nH2O enters the dryer 9 after being washed again to be dried, and then enters the pulverizer 10 to be pulverized to obtain white carbon black products;

[0014] V. High-temperature evaporation is carried out in the evaporation device 12, sodium fluoride crystals are precipitated, the top outlet of the evaporation device 12 is used to discharge water vapor, the water vapor is cooled into liquid by the spiral pipeline 15 in the sodium carbonate storage tank 3 and then connected to the cleaning device 7 to clean the cleaning device 7, at this time the external water source is closed; the heat exchange process of the spiral pipeline 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 to be filtered, the filtering device 13 is used to filter and recycle sodium fluoride solid products, and the remaining filtrate returns to the sodium carbonate storage tank 3 for recycling.

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

[0016] The present application provides a production process method and system for preparing high-quality white carbon black and co-producing sodium fluoride by using waste sodium fluorosilicate in phosphorus fertilizer production as raw material. The present application successfully solves the problems of high-temperature conditions, high equipment requirements and expensive device price in conventional gas-phase white carbon black production under the premise of producing high-quality white carbon black, solves the problem of low-efficiency utilization of low-cost waste sodium fluorosilicate in the phosphorus fertilizer industry, provides a new process route and system for continuous production of white carbon black by precipitation method, and provides a new optional way for resource utilization of fluorine and silicon. The present application has a positive significance and role for improving the comprehensive utilization of fluorine and silicon resources, protecting the environment, improving the benefits, developing more high-value-added products and promoting the development of fluorine chemical industry. BRIEF DESCRIPTION OF DRAWINGS

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

[0018] Specific embodiment 1: This embodiment 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 crusher 10, a liquid storage tank 11, an evaporator 12, a filtering device 13, a third pump 14 and a spiral pipe 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 set between the sodium fluorosilicate storage tank 1 and the reactor 5, and a second pump 4 is set 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 carbon dioxide gas generated in the reaction and condensing 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 valves; the top of the cleaning device 7 is provided with an outlet It is connected to the inlet of the liquid storage tank 11; 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 upper and middle 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 crusher 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, with the inlet of the spiral pipe 15 at the bottom and the outlet of the spiral pipe 15 at the top.

[0020] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that electromagnetic valves are provided at the bottom of the precipitation device 6 and the cleaning device 7. Other aspects are the same as those of specific embodiment 1.

[0021] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that a heating wire is provided on the reactor 5. Other aspects are 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. The specific process is as follows:

[0023] 1. Mixing sodium fluorosilicate with water and heating it to increase the solubility of sodium fluorosilicate in water, and then transferring the mixture to sodium fluorosilicate storage tank 1; transferring an aqueous sodium carbonate solution prepared in a specific molar ratio of sodium fluorosilicate and sodium carbonate to sodium carbonate storage tank 3;

[0024] Second, the sodium fluorosilicate aqueous solution and the sodium carbonate aqueous solution are pumped into the reactor 5 by the first pump 2 and the second pump 4 respectively for mixing, and the reactor 5 is heated. The sodium fluorosilicate and the sodium carbonate react to generate SiO2·nH2O and sodium fluoride. The sodium fluoride dissolves 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. 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;

[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 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 settled 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 the 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] V. The high-temperature evaporation is carried out in the evaporation device 12, and sodium fluoride crystals are precipitated. The top outlet of the evaporation device 12 is used to discharge water vapor, which is cooled into liquid by the spiral pipeline 15 in the sodium carbonate storage tank 3 and then connected to the cleaning device 7 to clean the cleaning device 7. At this time, the external water source is closed. The heat exchange process of the spiral pipeline 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 recycle the solid product of sodium fluoride, and the remaining filtrate is returned to the sodium carbonate storage tank 3 for recycling.

[0028] Specific embodiment V: The difference between this embodiment and specific embodiment IV is that in step one, the sodium fluosilicate is mixed with water, heated to 75°C and stirred at a stirring speed of 100 r / min-200 r / min for 10 min-20 min, and then transferred to the sodium fluosilicate storage tank 1. The others are the same as specific embodiment IV.

[0029] Specific embodiment VI: The difference between this embodiment and specific embodiment V is that in step one, the mass fraction of the sodium carbonate aqueous solution is 30%. The others are the same as specific embodiment V.

[0030] Specific embodiment VII: The difference between this embodiment and specific embodiment VI is that in step two, the flow rate of the sodium fluosilicate aqueous solution and the sodium carbonate aqueous solution pumped into the reactor 5 is 13 L / h-16 L / h. The others are the same as specific embodiment VI.

[0031] Specific embodiment VIII: The difference between this embodiment and specific embodiment VII is that in step two, the molar ratio of sodium fluosilicate to sodium carbonate in the reactor 5 is 1:(3-4). The others are the same as specific embodiment VII.

[0032] Specific embodiment IX: The difference between this embodiment and specific embodiment VIII is that in step two, the heating temperature of the reactor 5 is 65°C-80°C; and in step four, the drying temperature of the dryer 9 is 120°C. The others are the same as specific embodiment VIII.

[0033] Specific embodiment X: The difference between this embodiment and specific embodiment IX is that in step three, the time for the bottom valve of the precipitation device 6 and the cleaning device 7 to be in the open state is 1 s-2 s, and the time for the bottom valve to be in the closed state is 1 min-2 min, so that the SiO2·nH2O precipitate is discharged. The others are the same as specific embodiment IX.

[0034] The following test is used to verify the present application:

[0035] Test I: This test is a system for preparing white carbon black from sodium fluosilicate and co-producing sodium fluoride, as shown inFigure 1 As shown, specifically by sodium fluosilicate storage tank 1, the first pump 2, sodium carbonate storage tank 3, the second pump 4, reactor 5, precipitation device 6, cleaning device 7, washing device 8, dryer 9, crusher 10, liquid storage tank 11, evaporator 12, filter device 13, third pump 14 and spiral pipe 15; the reactor 5 is provided with heating wire;

[0036] The outlet of the sodium fluosilicate storage tank 1 and the outlet of the sodium carbonate storage tank 3 are respectively communicated with the inlet of the reactor 5, the first pump 2 is arranged between the sodium fluosilicate storage tank 1 and the reactor 5, and the second pump 4 is arranged between the sodium carbonate storage tank 3 and the reactor 5; the outlet of the reactor 5 is communicated with the upper inlet of the precipitation device 6, the top of the precipitation device 6 is provided with an exhaust pipe 6-2 with condensing function for discharging carbon dioxide gas generated in the reaction, and the water vapor is condensed into liquid and returned to the precipitation device 6, the condensing part of the exhaust pipe 6-2 is connected with 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 communicated with the inlet of the liquid storage tank 11, the bottom outlet of the precipitation device 6 is communicated with the top inlet of the cleaning device 7, and the lower part of the side wall of the cleaning device 7 is communicated with the external water source; the bottom of the precipitation device 6 and the cleaning device 7 is provided with an electromagnetic valve; the top of the cleaning device 7 is provided with an outlet communicated with the inlet of the liquid storage tank 11; the bottom outlet of the cleaning device 7 is communicated with the inlet of the washing device 8, the lower part of the side wall of the washing device 8 is communicated with the external water source, the bottom outlet of the washing device 8 is communicated with the inlet of the dryer 9, the upper middle outlet of the washing device 8 is communicated with the inlet of the liquid storage tank 11, and the outlet of the dryer 9 is communicated with the inlet of the crusher 10; the bottom outlet of the liquid storage tank 11 is communicated with the inlet of the evaporator 12, the bottom outlet of the evaporator 12 is communicated with the inlet of the filter device 13, and the filtrate outlet of the filter device 13 is communicated with the inlet of the sodium carbonate storage tank 3; the top outlet of the evaporator 12 is communicated with the inlet of the spiral pipe 15, the outlet of the spiral pipe 15 is communicated with the inlet of the third pump 14, the outlet of the third pump 14 is communicated with 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 below, and the outlet of the spiral pipe 15 is above.

[0037] Test two: this test is the use method of the system for preparing white carbon black and co-producing sodium fluoride by using sodium fluosilicate as raw material in test one, and the specific process is as follows:

[0038] One, the sodium fluosilicate is mixed with water, heated to 75℃ and stirred, the stirring speed is 100r / min-200r / min, the stirring time is 10min-20min, then transferred to the sodium fluosilicate storage tank 1; The sodium carbonate aqueous solution prepared according to the specific molar ratio of sodium fluosilicate and sodium carbonate is transferred to the sodium carbonate storage tank 3; The sodium fluosilicate is the waste sodium fluosilicate in phosphate fertilizer industry; The mass fraction of the sodium carbonate aqueous solution is 30%;

[0039] Two, the sodium fluosilicate aqueous solution and the sodium carbonate aqueous solution are pumped into the reactor 5 for mixing by the first pump 2 and the second pump 4 respectively, the reactor 5 is heated to 70℃, the sodium fluosilicate and the sodium carbonate react to generate SiO2·nH2O and sodium fluoride, the sodium fluoride is dissolved in the hot solution and taken into the precipitation device 6 with SiO2·nH2O and water flow; The flow rate of the sodium fluosilicate aqueous solution and the sodium carbonate aqueous solution pumped into the reactor 5 is 15L / h; The molar ratio of the sodium fluosilicate and the sodium carbonate in the reactor 5 is 1:3;

[0040] Three, after entering the precipitation device 6, SiO2·nH2O naturally settles at the bottom of the container, the bottom is controlled by a valve, the opening time of the bottom valve is 1s-2s, and the closing time is 1min-2min, so that SiO2·nH2O and a small amount of orthosilicic acid solution enter the cleaning device 7, and the supernatant of the precipitation device 6 is discharged to the storage tank 11 through the overflow weir 6-1;

[0041] Four, the lower part of the side wall of the cleaning device 7 is connected with an external water source, the water flow rate is controlled to be 25L / h so as not to affect the settling process of SiO2·nH2O and at the same time can make the orthosilicic acid flow out of the device from the top outlet of the cleaning device 7 and discharged to the storage tank 11, the liquid in the storage tank 11 is discharged to the evaporation device 12, SiO2·nH2O settles at the bottom of the cleaning device 7, the opening time of the bottom valve of the cleaning device 7 is 1s, and the closing time is 2min, so as to discharge the SiO2·nH2O precipitate to the washing device 8, the lower part of the side wall of the washing device 8 is connected with an external water source, the water flow rate is 25L / h, SiO2·nH2O enters the dryer 9 after being washed again, the drying temperature is 120℃, then enters the pulverizer 10 for pulverization treatment, and the white carbon black product is obtained;

[0042] V. The high-temperature evaporation is carried out in the evaporation device 12, and sodium fluoride crystals are precipitated. The water vapor is discharged from the top outlet of the evaporation device 12, and is cooled into liquid by the spiral pipeline 15 in the sodium carbonate storage tank 3, and then is connected to the cleaning device 7 to clean the cleaning device 7. At this time, the external water source is closed. The heat exchange process of the spiral pipeline 15 can also heat the sodium carbonate solution. The remaining sodium carbonate solution, the original silicon acid solution and the sodium fluoride in the evaporation device 12 are transferred to the filtering device 13 through the bottom outlet for filtering. The filtering device 13 is used for filtering and recycling the solid product of sodium fluoride, and the remaining filtrate is returned to the sodium carbonate storage tank 3 for recycling.

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

[0044] Table 1 Classification of white carbon black

[0045] Category Nitrogen adsorption specific surface area, m 2 / g]]> Category 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 the industry standard, sodium fluoride is divided into three grades according to chemical composition, as shown in Table 2:

[0047] Table 2 Classification of sodium fluoride

[0048]

[0049] The results of the physical property parameter determination of the white carbon black and sodium fluoride prepared in test two are as follows:

[0050] Table 3 Physical property parameters of white carbon black

[0051] Serial number Detection item Indicator Result Detection method 1 Silica content (ignition product), % 95～98 96.8 HG / T 3062 2 Specific surface area, m 2 / g]] Class A ≥ 191 317 GB / T 10722 3 Ignition loss (dry product), % ≤7.0 2.34 HG / T 3066 4 Heating loss, % 4.0～8.0 4.67 HG / T 3065 5 45 μm sieve residue, % ≤0.5 0.01 HG / T 3064 6 Oil absorption, 10 -5 m 3 ·kg -1 ]]> 200～350 220 HG / T 3072 7 pH value 5.0～8.0 7.3 HG / T 3067

[0052] From the results in Table 3 above, the specific surface area of the white carbon black prepared in test two is 317 m 2 / g, which meets the requirements of A type white carbon black in HG / T3061-2020.

[0053] Table 4 Physical property parameters of sodium fluoride

[0054] Serial number Detection item Primary indicator Result Detection method 1 Sodium fluoride content, % ≥98 98.4 YS / T 535.2-2009 2 Silica 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 Moisture 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, the sodium fluoride product prepared in test two meets the chemical composition requirements of first-class sodium fluoride product.

[0056] Test three: This test differs from test two in that:

[0057] The molar ratio of sodium fluosilicate to sodium carbonate in reactor 5 in step two was 1 :3.5;

[0058] Reactor 5 was heated to 80°C in step two;

[0059] The flow rate of both the aqueous sodium fluosilicate solution and the aqueous sodium carbonate solution into reactor 5 in step two was 13 L / h. Otherwise the same as test two.

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 a 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 pipe (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); an exhaust pipe (6-2) with a condensing function is arranged on the top of the precipitation device (6) for discharging carbon dioxide gas generated in the reaction and condensing water vapor into liquid The liquid is returned to the precipitation device (6), and the condensation part of the exhaust pipe (6-2) is connected to the external cooling water; an overflow weir (6-1) is provided on the outer wall of the precipitation device (6), and 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 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 the 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 crusher (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), 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). 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. The 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. The 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 raw material according to 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 the mixture to increase the solubility of the sodium fluorosilicate in water, and then transferring the mixture to a sodium fluorosilicate storage tank (1); transferring a sodium carbonate aqueous solution prepared according to a specific molar ratio of sodium fluorosilicate to 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) through 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, which is dissolved in the hot solution and carried into the precipitation device (6) along 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 20L / h~30L / h so that it does not affect the sedimentation process of SiO2·nH2O. At the same time, the original silicic 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 evaporator (12). SiO2·nH2O is settled 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 the external water source. After being washed again, SiO2·nH2O enters the dryer (9) for drying, and then enters the crusher (10) for crushing to obtain a white carbon black product; Fifth, high-temperature evaporation is performed in the evaporator (12) to precipitate sodium fluoride crystals. The top outlet of the evaporator (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 evaporator (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 sodium fluorosilicate aqueous solution and the sodium carbonate aqueous solution are pumped into the reactor (5) at a flow rate of 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 1s to 2s and in the closed state for 1min to 2min, thereby discharging the SiO2·nH2O precipitate.

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