A method for preparing white carbon black and co-producing ammonium fluoride

Abstract

The present invention belongs to the technical field of silicon dioxide, and specifically relates to a method for preparing white carbon black and co-producing ammonium fluoride. The method for preparing white carbon black and co-producing ammonium fluoride provided by the present invention comprises the following steps: mixing an ammonium fluoride solution, silicon tetrafluoride gas and ammonia gas in a supergravity reaction bed for reaction, aging and filtering after the reaction, washing and drying the filtered solid to obtain white carbon black, and the filtered liquid is an ammonium fluoride solution. By utilizing the strong mass transfer effect of the reactor, the gas is fully dispersed in the solution, the activity of the primary silicon dioxide crystals is improved, and the ammonium fluoride solution as a buffer medium improves the stability of silicon dioxide precipitation, which is beneficial to the high-quality formation of SiO2 and greatly improves the specific surface area of ​​the white carbon black product. The specific surface area of ​​the obtained white carbon black can reach 190~290m 2 / g, the oil absorption value can reach 2.3~2.7mL / g.

Description

Technical Field

[0001] The invention relates to the technical field of silicon dioxide, and in particular to a method for preparing white carbon black and co-producing ammonium fluoride. Background Art

[0002] White carbon black, also known as hydrated silicon dioxide, is a white amorphous fine powder inorganic silicon compound with excellent properties such as porosity, high dispersibility, light weight, good chemical stability, high temperature resistance, non-combustibility, and good electrical insulation. It is widely used in many fields such as plastics, rubber, papermaking, coatings, dyes and inks.

[0003] The production process of silica mainly includes two methods: gas phase method and precipitation method. The raw materials of silica produced by gas phase method are generally silicon tetrachloride, oxygen and hydrogen, which are reacted at high temperature. Its advantages are high product purity, high dispersion, fine particles forming a spherical shape, and few surface hydroxyls, so it has excellent reinforcement properties, but the raw materials are expensive, the energy consumption is high, the technology is complex, the equipment requirements are high, and a large amount of hydrochloric acid is produced as a by-product, which limits the application of this method. The precipitation method is prepared by reacting sodium silicate with carbon dioxide, hydrochloric acid, sulfuric acid, etc. The raw materials used in this method are cheap and easy to obtain, the production process and equipment are relatively simple, and the product price is low, so it currently occupies a dominant position.

[0004] Fluorosilicic acid is a by-product of the wet-process phosphoric acid production process, in which fluorine escapes in the form of silicon tetrafluoride. Fluorosilicic acid is prepared using water as an absorption medium, and further prepared into products such as fluorosilicates, fluoride salts and anhydrous hydrogen fluoride to achieve resource utilization. The market demand for fluorosilicic acid and fluorosilicates is small, and the product value is low; the process of preparing hydrogen fluoride and fluoride salts from fluorosilicic acid is long, and silicon is generally not effectively utilized during the fluorine-silicon separation process, which will cause secondary pollution.

[0005] Separating the fluorine element from the silicon tetrafluoride and fluorosilicic acid produced in the wet-process phosphoric acid production process and preparing fluoride and white carbon black respectively not only effectively utilizes fluorine resources, but also improves the utilization value of silicon. At present, the production of high-quality white carbon black by fluorosilicic acid amination is an intermittent process, that is, firstly preparing SiO by fluorosilicic acid amination. 2 Seed crystals are then used as "seeds" to continue adding fluorosilicic acid and ammonia water, and high specific surface area white carbon black and ammonium fluoride solution are obtained through process conditions. The ammonium fluoride solution is concentrated, crystallized, dried, and other processes to obtain solid ammonium bifluoride products. This type of method uses ammonia water for amination reaction. The disadvantage is that a large amount of water is brought into the system with low-concentration ammonia water. A large amount of water needs to be removed by evaporation in the later stage, which greatly increases the cost. It is difficult to obtain high specific surface area white carbon black by hydrolysis under fluorine-containing acidic conditions using silicon tetrafluoride as the raw material. The specific surface area ranges from 45 to 400 m 2 / g, there is a large amount of low value-added white carbon black.

[0006] The Chinese patent application with application publication number CN118183763A published on June 14, 2024 discloses a method for preparing white carbon black and ammonium fluoride from silicon tetrafluoride, which is to react silicon tetrafluoride gas and ammonia with a carrier gas in an ammoniation reactor to generate solid particles SiO 2 and NH 4 F, and the solid slurry formed after spray washing with the carrier gas is settled, and the SiO 2 and NH 4 F, this method uses silicon tetrafluoride gas produced as a byproduct of phosphate fertilizer or SiF obtained by decomposing fluorosilicic acid 4 Gas is used as raw material to realize continuous production of white carbon black and ammonium fluoride, improve the quality of white carbon black products, and the specific surface area of ​​white carbon black reaches 100~150m 2 / g, continuous, stable, simple and with a long operation cycle, effectively overcoming the shortcomings of existing intermittent process technology.

[0007] However, in the above-mentioned method for preparing white carbon black and ammonium fluoride, the gas-gas reaction of silicon tetrafluoride gas and ammonia is adopted, and the reaction speed is fast, which is not conducive to the high specific surface area SiO 2 The generation of SiO 2 and NH 4 F separation is incomplete, and there is a situation where silicon dioxide and ammonium fluoride fine particles stick to each other, which reduces the use and market value of the product. Summary of the invention

[0008] The invention provides a method for preparing white carbon black and co-producing ammonium fluoride, which solves the technical problem of low activity of white carbon black in the prior art when preparing white carbon black and ammonium fluoride.

[0009] In order to solve the above technical problems, the technical solution of the method for preparing white carbon black and co-producing ammonium fluoride of the present invention is: A method for preparing white carbon black and co-producing ammonium fluoride comprises the following steps: mixing an ammonium fluoride solution, silicon tetrafluoride gas and ammonia gas in a supergravity reaction bed for reaction, aging and filtering after the reaction, washing and drying the filtered solid to obtain white carbon black, and the filtered liquid is an ammonium fluoride solution.

[0010] The present invention is an improvement on the prior art, and provides a method for preparing white carbon black and co-producing ammonium fluoride. The method realizes gas-liquid reaction by reacting ammonium fluoride solution, silicon tetrafluoride gas and ammonia in a supergravity reaction bed, and utilizes the strong mass transfer effect of the reactor to fully disperse the gas in the solution, thereby improving the uniformity of the reaction and avoiding the problem of poor activity of primary silicon dioxide grains produced by local reaction of silicon tetrafluoride and ammonia in conventional reactors. The reaction equation is as follows: SiF 4 + 4NH3 + 2H 2 O → 4NH 4 F + SiO 2 ↓ Among them, the following reaction equilibrium exists: In the preparation method provided by the present invention, in the presence of ammonium fluoride, silicon tetrafluoride is dissolved in water to generate ammonium fluorosilicate, which is further ammonolyzed to obtain silicon dioxide and ammonium fluoride, and the ammonium fluoride solution becomes a buffer medium for the preparation of ammonium fluorosilicate and the precipitation of silicon dioxide.

[0011] This buffering effect improves the stability of silica precipitation and is beneficial to SiO 2 The high-quality formation of silica products greatly improves the specific surface area and oil absorption value of silica products to achieve high activity of silica, and at the same time achieves the co-production of high-activity silica and ammonium fluoride. The silica and ammonium fluoride solutions can be separated by filtration. The specific surface area of ​​silica obtained by the preparation method of the present invention can reach 150~350m 2 / g, the oil absorption value can reach 2.3~2.7mL / g; and the use of ammonium fluoride solution as a buffer solution makes the reaction more stable and controllable, and the gas-liquid reaction system reacts more fully; after the reaction is completed, the solid-liquid separation of the reaction products is more complete and simpler than the solid-solid separation using density difference in the prior art, and will not affect the availability and commerciality of the product.

[0012] In the absence of ammonium fluoride, silicon tetrafluoride gas and ammonia are introduced into the aqueous solution together, silicon tetrafluoride is hydrolyzed to obtain fluorosilicic acid and silicon dioxide, and then reacted with ammonia to obtain ammonium fluorosilicate (as shown in the following formula), thereby achieving the co-production of white carbon black and ammonium fluoride. However, the stacking structure of silicon dioxide particles precipitated after direct hydrolysis of silicon tetrafluoride is uncontrollable, and the activity of silicon dioxide is poor, so it cannot be used as a white carbon black product.

[0013] The preparation method provided by the present invention uses silicon tetrafluoride and ammonia as raw materials to prepare ammonium fluoride and high-performance silicon dioxide. Compared with using fluorosilicic acid and ammonia water as raw materials, the adaptability of the raw materials is improved, the amount of water introduced into the reaction system is reduced, and it is beneficial to the subsequent concentration of ammonium fluoride, so that energy consumption is reduced and production costs are improved; the obtained ammonium fluoride can be further used to prepare various fluoride salts, anhydrous hydrogen fluoride and other products, so that high-quality utilization of fluorine resources is achieved and the application field of silicon tetrafluoride is expanded.

[0014] The preparation method provided by the present invention can achieve high-quality utilization of low-grade fluorine resources produced as a by-product of phosphorus chemical industry, improve the healthy and sustainable development level of the fluorine chemical industry, achieve high-quality utilization of silicon on the basis of ensuring efficient separation of fluorine and silicon, and does not generate secondary pollution, which is in line with the production concept of comprehensive resource utilization, energy conservation and environmental protection.

[0015] By controlling the temperature of the ammonium fluoride solution, the temperature of the reaction system can be controlled, the absorption effect of the solution on the gas is improved, the primary silicon dioxide crystals are ensured to be uniformly precipitated under appropriate temperature conditions, and the stability of silicon dioxide precipitation is improved. Preferably, the temperature of the ammonium fluoride solution is 40-60° C. More preferably, the temperature of the ammonium fluoride solution is 40-50° C.

[0016] Preferably, the pH of the system is adjusted before aging to 7-7.5. By adjusting the pH of the system before aging, the perfect growth of secondary silicon dioxide grains can be achieved, and by adjusting the pH of the system before aging, the solubility of silicon dioxide can be controlled, the silicon dioxide content in the solution can be reduced, and the silicon dioxide yield can be increased.

[0017] In order to further fully carry out the reaction, preferably, the molar ratio of the silicon tetrafluoride gas to the ammonia gas is 1: (3-4.5). More preferably, the molar ratio of the silicon tetrafluoride gas to the ammonia gas is 1: (3.5-4.5).

[0018] In order to further improve the absorption effect of the ammonium fluoride solution on the raw gas and increase the gas-liquid reaction rate, preferably, the initial concentration of the ammonium fluoride solution is 10-50 g / L, and the ratio of the volume of the ammonium fluoride solution to the sum of the masses of silicon tetrafluoride gas and ammonia gas is (1-1.2) L: (100-220) g.

[0019] In order to further control the quality of silicon dioxide grain growth, preferably, the reaction is continued until the concentration of the ammonium fluoride solution increases to 250-700% of the initial concentration, and then aging and filtering are performed. Specifically, when the initial concentration of the ammonium fluoride solution is 10-50 g / L, the reaction is continued until the concentration of the ammonium fluoride solution increases to 62.5-120 g / L, and then aging and filtering are performed.

[0020] In order to further increase the specific surface area and yield of silicon dioxide, preferably, the aging temperature is 40-60°C and the aging time is 1-3 hours. More preferably, the aging temperature is 40-50°C.

[0021] In order to further improve the mass transfer effect and enhance the growth quality of silicon dioxide grains, preferably, the rotation speed of the ultra-gravity rotating bed is 1000 rpm to 1500 rpm.

[0022] In order to further improve the raw material utilization rate of the high gravity rotating bed, preferably, when the high gravity rotating bed is used for reaction, the inlet flow rate of silicon tetrafluoride gas is 5.2-10.4 g / min, and the inlet flow rate of ammonia gas is 3.4-6.8 g / min.

[0023] In order to further regulate the growth of primary silicon dioxide grains, preferably, when the reaction is carried out in a high gravity rotating bed, the circulation flow rate of the ammonium fluoride solution is 200-500 mL / min. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of the method for preparing white carbon black and co-producing ammonium fluoride according to Example 1 of the present invention. DETAILED DESCRIPTION

[0025] The technical concept of the method for preparing white carbon black and co-producing ammonium fluoride provided by the present invention is as follows: In the prior art, in the method of using silicon tetrafluoride to prepare white carbon black and co-produce fluoride, firstly, the obtained white carbon black has a low specific surface area and low added value, and secondly, there is the problem of separation of white carbon black and fluoride, which further affects the product quality and commerciality of white carbon black. The Chinese patent application with application publication number CN113929101A, which was applied for and published on January 14, 2022, discloses a method for co-producing white carbon black and fluorosilicate using silicon tetrafluoride tail gas, wherein the silicon tetrafluoride gas obtained after dust removal and purification of the waste gas containing silicon tetrafluoride is introduced into deionized water, rapidly stirred and hydrolyzed to generate a slurry containing silicon dioxide, which is filtered and filtered to obtain white carbon black. However, in fact, the silica gel obtained by direct hydrolysis of silicon tetrafluoride cannot be effectively controlled due to the precipitation process, and only inactive silicon slag is obtained, which does not have the property of high specific surface area; the Chinese patent with authorization announcement number CN1110450C, which was authorized on June 4, 2003, discloses a method for co-producing white carbon black and fluorosilicate from silicon tetrafluoride tail gas. In a method for preparing activated white carbon black by one-step hydrolysis of silicon, the silicon tetrafluoride gas after dust removal and purification is directly introduced into deionized water containing an appropriate amount of surfactant, and the white carbon black is obtained by rapid stirring and hydrolysis. The silicon dioxide grains obtained by direct hydrolysis cannot grow in a controllable manner, and inactive silicon slag with a low specific surface area is finally formed. A Chinese patent with an authorization announcement number of CN104843712B, which was authorized on July 4, 2017, discloses a method for purifying industrial fluorosilicic acid and co-producing white carbon black. The method involves heating an industrial fluorosilicic acid solution after contact with silica powder, collecting the heated silicon tetrafluoride gas, absorbing it with an absorption liquid, and hydrolyzing it to obtain fluorosilicic acid and hydrated silicon dioxide. The method has the same problem of a low specific surface area.

[0026] The preparation method provided by the present invention utilizes the strong mass transfer effect of the supergravity reaction bed to fully disperse the gas in the solution, realize the uniformity of the gas-liquid reaction, and improve the activity of the primary silicon dioxide grains. During the reaction process, the ammonium fluoride solution is used as a buffer medium for the preparation of ammonium fluorosilicate and the precipitation of silicon dioxide, thereby improving the stability of the silicon dioxide precipitation, which is beneficial to the SiO 2 The high-quality formation of silica products greatly improves the specific surface area and oil absorption value of silica products to achieve high activity of silica. The specific surface area of ​​silica obtained by the preparation method of the present invention can reach 150~350m 2 / g, the oil absorption value can reach 2.3~2.7mL / g; and the use of ammonium fluoride solution as a buffer solution makes the reaction more stable and controllable, and the gas-liquid reaction system reacts more fully; the solid-liquid separation after the reaction is completed is more complete than the solid-solid separation using density difference in the existing technology, and will not affect the availability and commerciality of the product.

[0027] The ultra-gravity reactor bed has a strong mass transfer effect. The use of this type of reactor is conducive to improving the gas-liquid mixing effect during the reaction process and improving the mass transfer and heat transfer efficiency of the materials in the reactor. During the reaction process, the ammonium fluoride solution is used as the reaction circulation absorption liquid, and the silicon tetrafluoride gas and ammonia enter the reactor through precise metering and are quickly absorbed in the ammonium fluoride solution. The generated silicon dioxide is evenly dispersed in the solution. With the advantage of the strong mass transfer of the ultra-gravity reactor, it not only ensures that the two gas phases of silicon tetrafluoride and ammonia are fully dispersed in the solution, but also improves the uniformity of the reaction, avoiding the problem of poor quality of silicon dioxide primary grains produced by local reaction of silicon tetrafluoride and ammonia in conventional reactors.

[0028] It is to be understood that the activity of white carbon black refers to the specific surface area and oil absorption value of white carbon black.

[0029] In a specific embodiment, the filtered liquid is an ammonium fluoride solution, which is concentrated, cooled, crystallized, filtered, and dried to obtain solid ammonium fluoride.

[0030] In a specific embodiment, the washing is to use layered water to wash the filtered solid to remove the residual ammonium fluoride in the solid, the drying temperature is 120-200°C, and the drying time is 2-3 hours. Water and free ammonia are removed to obtain high-performance white carbon black.

[0031] In a specific embodiment, after the filtered ammonium fluoride solution is concentrated, a portion of the ammonium fluoride solution prepared with water to an initial concentration is returned to the reaction system for reaction to achieve the recycling of ammonium fluoride; the water may be evaporated water generated during evaporation and concentration.

[0032] In a specific embodiment, the ammonia can come from commercially available industrial-grade ammonia, or can be produced by decomposing ammonium fluoride; the silicon tetrafluoride can come from a phosphoric acid concentration process, or can be produced by thermal decomposition and calcination of fluorosilicate.

[0033] Since ammonium fluoride exists in the form of ions after being dissolved in water, the concentration of the ammonium fluoride solution is measured by the fluoride ion concentration in the solution, and the fluoride ion concentration is analyzed and determined by other conventional methods such as thorium nitrate titration method and ion selective electrode method.

[0034] The degree of aggregation of precipitated hydrated silica particles affects their usage characteristics. The voids where precipitated hydrated silica aggregates depend on the aggregation volume of the particles. This pore volume can be obtained by the volume of dibutyl phthalate absorbed by the precipitated hydrated silica. Therefore, the dibutyl phthalate absorption value (i.e., oil absorption value) can be used as a measure of the degree of aggregation of precipitated hydrated silica.

[0035] The test steps for oil absorption value are as follows: 1) According to the provisions of HG / T 3065, dry an appropriate amount of precipitated hydrated silica sample in a constant temperature drying oven at (105±2)℃ using a suitable open container for 1.5 h, then place it in a desiccator to cool to room temperature for use.

[0036] 2) Weigh 1 g of the dried sample, place it on a glass plate, and begin to add dibutyl phthalate dropwise at a faster rate.

[0037] 3) When the amount of dibutyl phthalate added is equal to 3 / 4 of the sample absorption value, gently mix with a glass rod to make the dibutyl phthalate and the sample evenly infiltrated, then stir and roll continuously to break all the granular samples. Continue to add dibutyl phthalate at a slower speed and stir and roll continuously. When the sample is completely infiltrated by dibutyl phthalate, the glass rod pushes the mixture with resistance and the volume of the mixture is significantly reduced. There is no debris when it is unfolded, and smooth blocks or small strips appear. When there is no dry powder, stop adding. At this time, the mixture can be rolled on the glass rod once or several times, which is the end point. Record the volume value of dibutyl phthalate consumed.

[0038] The embodiments of the present invention are further described below in conjunction with specific examples. The chemical reagents involved in the following examples are all commercially available conventional products unless otherwise specified.

[0039] 1. Specific embodiments of the method for preparing white carbon black and co-producing ammonium fluoride of the present invention Example 1 The method for preparing white carbon black and co-producing ammonium fluoride in the present embodiment is as follows: The flow chart of the method for preparing white carbon black and co-producing ammonium fluoride in this embodiment is as follows Figure 1As shown, 5L of ammonium fluoride solution with a fluoride ion concentration of 30g / L is prepared as the reaction circulation absorption liquid of the high-gravity rotating bed, the liquid circulation system of the high-gravity rotating bed is started, and external heat exchange is used to ensure the system temperature during the reaction process. The temperature of the ammonium fluoride solution is controlled to 50°C, and the circulation flow rate is controlled to 200ml / min; after the circulating liquid temperature is stable, the high-gravity rotating bed is started, and the rotation speed is adjusted to 1000rpm; the silicon tetrafluoride valve and flowmeter are opened, and the intake flow rate is controlled to 10.4g / min; the ammonia valve and flowmeter are opened, and the intake flow rate is controlled to 6.8g / min; the feeding conditions are controlled and the feeding is stopped after 1h.

[0040] The reaction slurry after the ultra-gravity reaction was transferred to an aging kettle for aging. Before aging, 10 mol / L ammonia water was added to adjust the pH to 7.5, and then the mixture was kept at 50°C for 1 hour for aging. The fluoride ion concentration in the filtered ammonium fluoride solution was 115 g / L, and SiO 2 The content is 0.5g / L; the filtered ammonium fluoride solution is concentrated, cooled, crystallized, filtered, and dried to obtain ammonium fluoride solid, wherein a part of the high-concentration ammonium fluoride solution obtained after concentration can be prepared with evaporated water into a low-concentration ammonium fluoride solution, and then re-entered into the high-gravity rotating bed as a reaction cycle absorption liquid for liquid circulation; the filtered white carbon black ointment is washed 3 times with 1L of pure water and then dried at 150°C for 12h to obtain a white carbon black product.

[0041] The test shows that the specific surface area of ​​white carbon black product is 264m 2 / g, and the oil absorption value DBP is 2.55mL / g.

[0042] Example 2 The method for preparing white carbon black and co-producing ammonium fluoride in the present embodiment is as follows: Prepare 5 L of ammonium fluoride solution with a fluoride ion concentration of 30 g / L as the reaction circulation absorption liquid of the high-gravity rotating bed, start the liquid circulation system of the high-gravity rotating bed, use external heat exchange to ensure the system temperature during the reaction, control the temperature of the ammonium fluoride solution to 60°C, and control the circulation flow rate to 200 ml / min; after the circulating liquid temperature stabilizes, start the high-gravity rotating bed, adjust the speed to 1000 rpm; open the silicon tetrafluoride valve and flowmeter, control the air intake flow rate to 5.2 g / min; open the ammonia valve and flowmeter, control the air intake flow rate to 3.4 g / min; control the feeding conditions and stop feeding after 1 hour.

[0043] The reaction slurry after the ultra-gravity reaction was transferred to an aging kettle for aging. Before aging, 10 mol / L ammonia water was added to adjust the pH to 7.5, and then the mixture was kept at 60°C for 1 hour for aging. The fluoride ion concentration of the ammonium fluoride solution after filtration was 75 g / L, and SiO 2The content is 0.3g / L; the filtered ammonium fluoride solution is concentrated, cooled, crystallized, filtered, and dried to obtain ammonium fluoride solid, wherein a part of the high-concentration ammonium fluoride solution obtained after concentration can be prepared with evaporated water into a low-concentration ammonium fluoride solution, and then re-entered into the high-gravity rotating bed as a reaction cycle absorption liquid for liquid circulation; the filtered white carbon black ointment is washed 3 times with 1L of pure water and then dried at 150°C for 12h to obtain a white carbon black product.

[0044] The test shows that the specific surface area of ​​white carbon black product is 196m 2 / g, and the oil absorption value DBP is 2.33mL / g.

[0045] Example 3 The method for preparing white carbon black and co-producing ammonium fluoride in the present embodiment is as follows: Prepare 5L of ammonium fluoride solution with a fluoride ion concentration of 30g / L as the reaction circulation absorption liquid of the high-gravity rotating bed, start the liquid circulation system of the high-gravity rotating bed, use external heat exchange to ensure the system temperature during the reaction, control the temperature of the ammonium fluoride solution to 40°C, and control the circulation flow rate to 200ml / min; after the circulating liquid temperature stabilizes, start the high-gravity rotating bed, adjust the speed to 1500rpm; open the silicon tetrafluoride valve and flowmeter, control the intake flow rate to 10.4g / min; open the ammonia valve and flowmeter, control the intake flow rate to 6.8g / min; control the feeding conditions and stop feeding after 1h.

[0046] The reaction slurry after the ultra-gravity reaction was transferred to an aging kettle for aging. Before aging, 10 mol / L ammonia water was added to adjust the pH to 7.5, and then the mixture was kept at 40°C for 1 hour for aging. The fluoride ion concentration of the ammonium fluoride solution after filtration was 115 g / L, and the SiO 2 The content is 0.5g / L; the filtered ammonium fluoride solution is concentrated, cooled, crystallized, filtered, and dried to obtain ammonium fluoride solid, wherein a part of the high-concentration ammonium fluoride solution obtained after concentration can be prepared with evaporated water into a low-concentration ammonium fluoride solution, and then re-entered into the high-gravity rotating bed as a reaction cycle absorption liquid for liquid circulation; the filtered white carbon black ointment is washed 3 times with 1L of pure water and then dried at 150°C for 12h to obtain a white carbon black product.

[0047] The test shows that the specific surface area of ​​white carbon black product is 287m 2 / g, and the oil absorption value DBP is 2.67mL / g.

[0048] Example 4 The method for preparing white carbon black and co-producing ammonium fluoride in the present embodiment is as follows: Prepare 5L of ammonium fluoride solution with a fluoride ion concentration of 30g / L as the reaction circulation absorption liquid of the high-gravity rotating bed, start the liquid circulation system of the high-gravity rotating bed, use external heat exchange to ensure the system temperature during the reaction, control the temperature of the ammonium fluoride solution to 40°C, and control the circulation flow rate to 200ml / min; after the circulating liquid temperature stabilizes, start the high-gravity rotating bed, adjust the speed to 1000rpm; open the silicon tetrafluoride valve and flowmeter, control the air intake flow rate to 10.4g / min; open the ammonia valve and flowmeter, control the air intake flow rate to 6.8g / min; control the feeding conditions and stop feeding after 1h.

[0049] The reaction slurry after the ultra-gravity reaction was transferred to an aging kettle for aging. Before aging, 10 mol / L ammonia water was added to adjust the pH to 7, and then the mixture was kept at 40°C for 3 hours for aging. The fluoride concentration of the ammonium fluoride solution after filtration was 115 g / L, and the SiO 2 The content is 0.5g / L; the filtered ammonium fluoride solution is concentrated, cooled, crystallized, filtered, and dried to obtain ammonium fluoride solid, wherein a part of the high-concentration ammonium fluoride solution obtained after concentration can be prepared with evaporated water into a low-concentration ammonium fluoride solution, and then re-entered into the high-gravity rotating bed as a reaction cycle absorption liquid for liquid circulation; the filtered white carbon black ointment is washed 3 times with 1L of pure water and then dried at 150°C for 12h to obtain a white carbon black product.

[0050] The test shows that the specific surface area of ​​white carbon black product is 294m 2 / g, and the oil absorption value DBP is 2.65mL / g.

[0051] Example 5 The method for preparing white carbon black and co-producing ammonium fluoride in the present embodiment is as follows: Prepare 5L of ammonium fluoride solution with a fluoride ion concentration of 15g / L as the reaction circulation absorption liquid of the high-gravity rotating bed, start the liquid circulation system of the high-gravity rotating bed, use external heat exchange to ensure the system temperature during the reaction, control the temperature of the ammonium fluoride solution to 40°C, and control the circulation flow rate to 200ml / min; after the circulating liquid temperature stabilizes, start the high-gravity rotating bed, adjust the speed to 1500rpm; open the silicon tetrafluoride valve and flowmeter, control the air intake flow rate to 10.4g / min; open the ammonia valve and flowmeter, control the air intake flow rate to 6.8g / min; control the feeding conditions and stop feeding after 1h.

[0052] The reaction slurry after the ultra-gravity reaction was transferred to an aging kettle for aging. Before aging, 10 mol / L ammonia water was added to adjust the pH to 7.5, and then the mixture was kept at 40°C for 1 hour for aging. The fluoride ion concentration of the ammonium fluoride solution after filtration was 102 g / L, and the SiO 2The content is 0.4g / L; the filtered ammonium fluoride solution is concentrated, cooled, crystallized, filtered, and dried to obtain ammonium fluoride solid, wherein a part of the high-concentration ammonium fluoride solution obtained after concentration can be prepared with evaporated water into a low-concentration ammonium fluoride solution, and then re-entered into the high-gravity rotating bed as a reaction cycle absorption liquid for liquid circulation; the filtered white carbon black ointment is washed 3 times with 1L of pure water and then dried at 150°C for 12h to obtain a white carbon black product.

[0053] The test shows that the specific surface area of ​​white carbon black product is 305m 2 / g, and the oil absorption value DBP is 2.87mL / g.

[0054] Example 6 The method for preparing white carbon black and co-producing ammonium fluoride in the present embodiment is as follows: Prepare 5L of ammonium fluoride solution with a fluoride ion concentration of 45g / L as the reaction circulation absorption liquid of the high-gravity rotating bed, start the liquid circulation system of the high-gravity rotating bed, use external heat exchange to ensure the system temperature during the reaction, control the temperature of the ammonium fluoride solution to 40°C, and control the circulation flow rate to 200ml / min; after the circulating liquid temperature stabilizes, start the high-gravity rotating bed, adjust the speed to 1500rpm; open the silicon tetrafluoride valve and flowmeter, control the air intake flow rate to 10.4g / min; open the ammonia valve and flowmeter, control the air intake flow rate to 6.8g / min; control the feeding conditions and stop feeding after 1h.

[0055] The reaction slurry after the ultra-gravity reaction was transferred to an aging kettle for aging. Before aging, 10 mol / L ammonia water was added to adjust the pH to 7.5, and then the mixture was kept at 40°C for 1 hour for aging. The fluoride ion concentration of the ammonium fluoride solution after filtration was 135 g / L, and the SiO 2 The content is 0.7g / L; the filtered ammonium fluoride solution is concentrated, cooled, crystallized, filtered, and dried to obtain ammonium fluoride solid, wherein a part of the high-concentration ammonium fluoride solution obtained after concentration can be prepared with evaporated water into a low-concentration ammonium fluoride solution, and then re-entered into the high-gravity rotating bed as a reaction cycle absorption liquid for liquid circulation; the filtered white carbon black ointment is washed 3 times with 1L of pure water and then dried at 150°C for 12h to obtain a white carbon black product.

[0056] The test shows that the specific surface area of ​​white carbon black product is 275m 2 / g, and the oil absorption value DBP is 2.45mL / g.

[0057] 2. Comparison Comparative Example 1 (without using a high gravity rotating bed) The method for preparing white carbon black and co-producing ammonium fluoride in this comparative example is as follows: 5 L of ammonium fluoride solution with a fluoride ion concentration of 30 g / L was prepared as the silicon tetrafluoride absorption bottom liquid, and a 10 L autoclave reactor was used as the reaction container. The reaction temperature was controlled at 50°C by introducing refrigerant into the wall of the reactor, the stirring rate was controlled at 200 rpm, the silicon tetrafluoride valve and flowmeter were opened, and the air intake flow rate was controlled at 10.4 g / min; the ammonia valve and flowmeter were opened, and the air intake flow rate was controlled at 6.8 g / min; and the feeding conditions were controlled and the feeding was stopped after 1 hour.

[0058] The reaction slurry after the reaction was transferred to an aging kettle for aging. Before aging, 10 mol / L ammonia water was added to adjust the pH to 7.5, and then the mixture was kept at 40°C for 1 hour for aging. The fluoride ion concentration of the ammonium fluoride solution after filtration was 115 g / L, and SiO 2 The content is 0.5 g / L; the filtered white carbon black ointment is washed three times with 1 L of pure water and then dried at 150° C. for 12 h to obtain a white carbon black product.

[0059] The test shows that the specific surface area of ​​white carbon black product is 132m 2 / g, and the oil absorption value DBP is 2.02mL / g.

[0060] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing white carbon black and co-producing ammonium fluoride, characterized in that: The following steps are involved: The ammonium fluoride solution, silicon tetrafluoride gas and ammonia gas are mixed and reacted in a supergravity reaction bed, and then aged and filtered. The filtered solid is washed and dried to obtain white carbon black, and the filtered liquid is the ammonium fluoride solution.

2. The method for preparing white carbon black and co-producing ammonium fluoride according to claim 1, characterized in that: The temperature of the ammonium fluoride solution is 40-60°C.

3. The method for preparing white carbon black and co-producing ammonium fluoride according to claim 1, characterized in that: The pH of the system is adjusted before aging to 7-7.

5.

4. The method for preparing white carbon black and co-producing ammonium fluoride according to claim 1, characterized in that: The molar ratio of the silicon tetrafluoride gas to the ammonia gas is 1:(3-4.5).

5. The method for preparing white carbon black and co-producing ammonium fluoride according to claim 1, characterized in that: The initial concentration of the ammonium fluoride solution is 10-50 g / L, and the ratio of the volume of the ammonium fluoride solution to the sum of the masses of silicon tetrafluoride gas and ammonia gas is (1-1.2) L: (100-220) g.

6. The method for preparing white carbon black and co-producing ammonium fluoride according to claim 1 or 5, characterized in that: The reaction is continued until the concentration of the ammonium fluoride solution increases to 250-700% of the initial concentration, and then aging and filtering are performed.

7. The method for preparing white carbon black and co-producing ammonium fluoride according to claim 1, characterized in that: The aging temperature is 40-60° C., and the aging time is 1-3 hours.

8. The method for preparing white carbon black and co-producing ammonium fluoride according to claim 1, characterized in that: The rotation speed of the ultra-gravity rotating bed is 1000 rpm to 1500 rpm.

9. The method for preparing white carbon black and co-producing ammonium fluoride according to claim 8, characterized in that: When the reaction is carried out using a high-gravity rotating bed, the inlet flow rate of silicon tetrafluoride gas is 5.2~10.4 g / min, and the inlet flow rate of ammonia gas is 3.4~6.8 g / min.

10. The method for preparing white carbon black and co-producing ammonium fluoride according to claim 8, characterized in that: When the reaction is carried out using a high gravity rotating bed, the circulation flow rate of the ammonium fluoride solution is 200~500mL / min.

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