Preparation method of superfine barium sulfate

Abstract

The invention provides a preparation method of superfine barium sulfate, which comprises the following steps: at room temperature, weighing a proper amount of industrial-grade barium chloride and a proper amount of industrial-grade sodium sulfate solid, adding water to prepare feed liquid with equal molar concentration, filtering impurities, and respectively filling the feed liquid into storage tanks; adjusting the flow rate of the diaphragm metering pump to 2.25-500L / h, then adjusting the two feed liquids to the same stable flow rate, so that the two feed liquids flow out of the storage tank at a set flow rate, enabling the two feed liquids flowing out of the storage tank to simultaneously enter a spherical exhaust pipe, carrying out rapid precipitation reaction to generate an emulsion containing superfine barium sulfate particles, enabling the emulsion to enter a product storage tank, and placing the emulsion in the product storage tank, and finally, centrifugally filtering the emulsion, washing with water, and centrifugally filtering again to obtain a superfine barium sulfate filter cake, thereby finishing the preparation. The small-size effect is utilized, the barium chloride feed liquid and the sodium sulfate feed liquid are rapidly and fully mixed in the spherical exhaust pipe, mixing and mass transfer between fluids are enhanced, and industrial preparation of superfine barium sulfate is facilitated.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of barium sulfate preparation method, and particularly relates to a preparation method of superfine barium sulfate. BACKGROUND

[0002] As an important inorganic chemical product, barium sulfate is widely used in industries such as paint, pigment, coating, ink, battery, papermaking, rubber, ceramic, enamel and spice due to its low price, wide raw material and non-toxicity. Barium sulfate has traditional barium sulfate and superfine barium sulfate. In application, the latter has better effect than the former because the traditional barium sulfate has the defects of wide particle size distribution and poor uniformity in solvent.

[0003] The market has high requirements for the uniformity of superfine barium sulfate, and the good product is in short supply. Therefore, it is urgent to prepare superfine barium sulfate with small particle size and narrow particle size distribution. Moreover, the value of superfine barium sulfate is much higher than that of traditional barium sulfate.

[0004] In the existing preparation method of superfine barium sulfate, an impinging stream microreactor with a characteristic size of 0.1-1mm is used. The impinging stream microreactor has the advantages of rapid and uniform mixing and narrow product particle size, but also has the disadvantages of easy clogging, small processing capacity, complicated operation, use of high-pressure nitrogen and the like, and cannot realize large-scale industrial production of superfine barium sulfate. Therefore, it is urgent to promote industrialization and put forward superfine barium sulfate with small particle size and high quality without increasing production cost.

[0005] Based on this, a preparation method of superfine barium sulfate is provided. SUMMARY

[0006] The technical problem to be solved by the application is to provide a preparation method of superfine barium sulfate to solve the problems in the background.

[0007] To solve the above technical problems, the technical scheme adopted by the application is as follows: a preparation method of superfine barium sulfate, comprising the following steps:

[0008] S1, at room temperature, an appropriate amount of industrial-grade barium chloride and an appropriate amount of industrial-grade sodium sulfate solid are weighed, and water is added to prepare barium chloride solution and sodium sulfate solution with equal molar concentration, respectively, and then the impurities are filtered and respectively loaded into a barium chloride solution storage tank and a sodium sulfate solution storage tank;

[0009] S2, then adjust the flow of the diaphragm metering pump communicated with the barium chloride solution tank and the sodium sulfate solution tank to 2.25L-500L / h respectively, for providing a stable pressure environment, and then rotate the opening of the diaphragm metering pump knob, adjust the two solutions to the same stable flow, so that the two solutions flow out of the tank at a set flow rate;

[0010] S3, the two solutions flowing out of the tank enter the spherical air suction pipe at the same time, and the rapid precipitation reaction generates a milk lotion containing superfine barium sulfate particles, and the milk lotion enters the product tank for placement;

[0011] S4, finally, the milk lotion is centrifuged, washed with water, and then centrifuged to obtain a superfine barium sulfate filter cake, and the preparation is completed.

[0012] As a further description of the application, the concentration of the barium chloride solution and the sodium sulfate solution is set to be between 0.1-2.4mol / L.

[0013] As a further description of the application, the inlet cross-sectional area of the spherical air suction pipe is 10.17mm 2 .

[0014] As a further description of the application, the flow rate is set to be between 3.47-20.83m / s.

[0015] Compared with the prior art, the application has the following advantages:

[0016] The application replaces the impinging stream microreactor with a characteristic size of 0.1-1mm with a spherical air suction pipe, utilizes the small size effect, rapidly and fully mixes the barium chloride solution and the sodium sulfate solution in the spherical air suction pipe, strengthens the mixing and mass transfer between fluids, and is beneficial to the industrialized preparation of superfine barium sulfate. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is the SEM comparison chart in Example 1 of the application; wherein (a) is a spherical air suction pipe; (b) is a microreactor;

[0018] Figure 2 is the SEM comparison chart in Example 4 of the application; wherein (a) is barium sulfate manufactured by Foshan Anyi Superfine Material Co., Ltd.; (b) is barium sulfate produced by Xincheng City Yuedong Chemical Factory;

[0019] Figure 3 is the SEM chart of barium sulfate manufactured by Hebei University of Science and Technology in Example 4 of the application. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0021] In the embodiments of the present application, a technical solution is provided: a preparation method of superfine barium sulfate, comprising the following steps:

[0022] S1, at room temperature, an appropriate amount of industrial-grade barium chloride and an appropriate amount of industrial-grade sodium sulfate solid are weighed, and water is added to prepare barium chloride liquid and sodium sulfate liquid with the same molar concentration, and the two liquids are filtered and then respectively loaded into a barium chloride liquid storage tank and a sodium sulfate liquid storage tank;

[0023] S2, then the flow rates of the diaphragm metering pumps connected to the barium chloride liquid storage tank and the sodium sulfate liquid storage tank are respectively adjusted to 2.25 L-500 L / h for providing a stable pressure environment, and the opening of the knob of the diaphragm metering pump is then rotated to adjust the two liquids to have the same stable flow rate so that the two liquids flow out of the storage tanks at the set flow rate;

[0024] S3, the two liquids flowing out of the storage tanks simultaneously enter a spherical air extraction pipe to rapidly precipitate and react to generate emulsion containing superfine barium sulfate particles, and the emulsion is placed in a product storage tank;

[0025] S4, finally, the emulsion is centrifuged, washed with water, and then centrifuged again to obtain a superfine barium sulfate filter cake, and the preparation is completed.

[0026] Then a part of the filter cake is added into 13 times the mass of barium sulfate (converted into dry barium) of water-containing agent emulsion, and the emulsion is evaporated to dryness by azeotropic distillation to obtain a powder, and the specific surface area of the BaSO4 powder is measured.

[0027] Another part of the filter cake is subjected to characterization of the particle size and morphology of BaSO4.

[0028] 1) Specific surface tester (BET) analysis:

[0029] The product specific surface analysis is performed by using a Tristar II 3020 type full-automatic physical adsorption instrument produced by Micromeritics Company, USA, and the performance index is as follows: specific surface area: 0.01 m 2 / g~no upper limit; pressure measurement: 0~1000mmHg; minimum detection of pore volume: 0.0001cc / g.

[0030] The detection process is first to make the powder sample into a tablet, and the treated sample is vacuum desorbed at a suitable temperature. Then the adsorption and desorption curves of the sample can be measured by passing nitrogen at-197℃ under liquid nitrogen. Then the specific surface area of BaSO4 can be calculated according to the obtained adsorption and desorption curves combined with the BET equation.

[0031] 2) Scanning electron microscope analysis:

[0032] The S4800-I type scanning electron microscope produced by Japan Hitachi Company is used to characterize the ultrafine particles of ultrafine barium sulfate. The working voltage is 3kV; the minimum resolution is 1nm (15kV), 1.4nm (1kV); the element analysis range is Be4-U92; the magnification is 20-800,000 times. The experimental results of particle size, morphology and dispersion degree of BaSO4 are observed and compared by SEM characterization.

[0033] The microreactor with a characteristic size of 0.1-1mm is compared, and under the conditions of reactant concentration of 0.8mol / L, feed flow rate of 10.42m / s, and room temperature, the feed cross-sectional area is 0.32mm 2 , and the prepared barium sulfate has a narrow particle size distribution, and the average particle size is 30nm.

[0034] In this embodiment, a spherical suction pipe is used, and a diaphragm metering pump is used as a power transmission device. The flow rate can be adjusted in the range of 2.25-500L / h. By using the small size effect, that is, under the conditions of the same reactant concentration and feed flow rate, only the feed cross-sectional area is changed, the prepared ultrafine barium sulfate has a narrow particle size distribution, and the average particle size is 30nm.

[0035] The prepared product is subjected to specific surface area analysis and product morphology determination, and the results are shown in Table 1;

[0036] Table 1 Influence of amplification effect on specific surface area of ultrafine barium sulfate

[0037]

[0038] From Table 1 and Figure 1 It can be seen that compared with the microreactor with a characteristic size of 0.1-1mm, the specific surface area and morphology of the ultrafine barium sulfate particles are still about 30nm when the feed cross-sectional area of the spherical suction pipe is 10.17mm 2 , and the particle size distribution is not uniform, which shows that for the microreactor, no amplification effect is generated at this time.

[0039] Since the ultrafine barium sulfate particles are spherical, the formula

[0040] d=6000 / (4.5×S)表 )

[0041] The size of the particle diameter can be calculated.

[0042] The calculation result is close to the size of the ultra-fine barium sulfate particles observed in the electron microscope photograph, so it can be determined that the specific surface area instrument determination result is in good agreement with the SEM result.

[0043] In the spherical suction pipe, the ultra-fine barium sulfate with small particle size and narrow distribution can be prepared, because the small channel size greatly shortens the diffusion time, compared with the micro-reactor, the fluid is repeatedly divided and combined, so that the molecular diffusion distance is reduced, and the reactants can reach the complete mixing in the radial direction in the millisecond level, and the mixing distance is microns.

[0044] If the micro-reactor wants to increase the feed flow rate under the premise of ensuring the feed cross-sectional area, the nitrogen pressure needs to be increased by increasing the feed flow, and the total pressure is 15 MPa, and the partial pressure is 1 MPa, which will lead to large energy consumption and safety hazards; if the micro-reactor wants to increase the feed flow rate under the premise of ensuring the feed flow, the feed cross-sectional area must be reduced, which will accelerate the blockage of the micro-reactor.

[0045] Compared with the maximum feed flow of 12 L / h of the micro-reactor in the nitrogen power transportation, it can also be seen that the processing capacity of the spherical suction pipe with a feed cross-sectional area of 10.17 mm 2 is very large, which is 381 L / h, which is 30 times higher than that of the micro-reactor, and can realize industrial production.

[0046] Example 2

[0047] A method for preparing ultra-fine barium sulfate, using a spherical suction pipe, using a diaphragm metering pump as a power delivery device, the flow rate is 381 L / h, and the reactant concentration is 0.8 mol / L. The fixed feed flow rate is 10.42 m / s at room temperature, and the spherical suction pipe with a feed cross-sectional area of 10.17 mm 2 is selected, and the concentrations of barium chloride solution and sodium sulfate solution are changed to 0.1 mol / L, 0.5 mol / L, 0.8 mol / L, 1.2 mol / L, and 2.4 mol / L. The specific surface area and morphology of the obtained product are determined, and the results are shown in Table 2.

[0048] Table 2 Influence of reactant concentration on specific surface area of ultra-fine barium sulfate

[0049]

[0050] As can be seen from Table 2, the particle size and morphology of the ultrafine barium sulfate particles show a trend of first decreasing and then increasing with the increase of the reactant concentration. When the concentration of the reactant is 1.2 mol / L, the prepared ultrafine barium sulfate has the smallest particle size of 25.17 nm.

[0051] This is because the initial concentration of the reaction solution not only affects the reaction rate, but also relates to the quality of the prepared reaction product. In the process of rapid precipitation reaction, the solute forms crystallization from the solution, which needs to go through the following two steps:

[0052] ① First, microcrystalline grains are generated as the cores of crystallization, which are called crystal nuclei;

[0053] ② Then, they grow into macroscopic crystals.

[0054] Only in the presence of a driving force, the crystal nuclei can be generated or grow, and the driving force is the supersaturation of the solution, that is, the concentration difference of the solution. The process of generating the crystal nuclei is called nucleation, and the process of growing the crystal nuclei is called crystal growth. With the increase of the concentration of the reactant, the supersaturation of the solution increases, and the increase of the supersaturation will increase the nucleation rate and the growth rate of the ultrafine barium sulfate, but the growth rate is much smaller than the nucleation rate, thereby the ultrafine barium sulfate is prepared. However, when the concentration reaches a certain limit, the viscosity of the reaction solution increases, a certain adhesion effect is formed, and the mixing contact resistance increases, which is not conducive to the generation of the crystal nuclei.

[0055] In addition, it is desired in industry to obtain high yield of ultrafine barium sulfate, and with the increase of the concentration of the reactant, the concentration of the byproduct sodium chloride also increases. If the concentration of sodium chloride in the waste liquid is high, sodium chloride can be recovered by evaporation, which can save energy consumption. Therefore, in order to ensure that the spherical ultrafine barium sulfate with small particle size, narrow particle size distribution and high yield can be prepared, the concentration of the reactant is selected to be 1.2 mol / L.

[0056] The experiment C Na2SO4 = 1.2 mol / L, C BaCl2 = 1.2 mol / L is substituted into the supersaturation formula:

[0057]

[0058] Among them, the ion concentration constant K sp is 1.1 x 10 -10 mol 2 dm -6 ,

[0059] The calculation shows that the supersaturation S is 1109, that is, a homogeneous nucleation reaction occurs. The supersaturation S is substituted into the nucleation rate formula:

[0060]

[0061] The nucleation rate is 4.28xl0 26 m -3 s -1 .

[0062] Example 3

[0063] A method for preparing superfine barium sulfate, using a spherical air extraction pipe, compared with a micro-reactor, the feed cross-sectional area is 10.17mm 2 , the feed flow rate is 3.47-20.83m / s, on this basis, the feed flow rate is increased, the maximum pressure of nitrogen is 1MPa, the feed flow rate is 20.83m / s, the reaction temperature is room temperature, the reactant concentration is fixed at 1.2mol / L, the reactor is a spherical air extraction pipe device with a feed cross-sectional area of 10.17mm 2 , the flow of the pump is adjusted, only the feed flow rate of the reactant is changed, which is 3.47m / s, 6.94m / s, 10.42m / s, and 20.83m / s respectively. The specific surface area and morphology of the obtained product were determined, and the results are shown in Table 3:

[0064] Table 3 Effect of reactant feed flow rate on specific surface area of superfine barium sulfate

[0065]

[0066] As can be seen from Table 3, with the increase of the flow rate of the reactant, the particle size and morphology of the superfine barium sulfate particles are decreasing, and the particle size of the superfine barium sulfate particles obtained at a reactant flow rate of 20.83m / s has reached 27.94nm.

[0067] The reaction process is: two kinds of reaction liquid form a certain flow rate under the power provided by the outside world, and the two collide to obtain superfine barium sulfate particles. When the speed is high, the rapid collision produces a large shear force, and the barium chloride and sodium sulfate are mixed under the action of the mutual shear force to achieve a high degree of uniformity, which is beneficial to the small size and uniformity of the product particles, thereby obtaining superfine barium sulfate particles with good uniformity. When the flow rate of the reactant is 10.42m / s, a very good micro-mixing effect is achieved, and the particle size of the superfine barium sulfate particles obtained at a reactant flow rate of 20.83m / s is not much different. In order to save consumption and avoid the explosion of the equipment at high pressure, the flow rate of the reactant is selected to be 10.42m / s.

[0068] Example 4

[0069] A method for preparing superfine barium sulfate, using a spherical air extraction pipe, the reaction temperature is room temperature, the reactant concentration is 1.2mol / L, the reactant feed flow rate is 10.42m / s, and the feed cross-sectional area is 10.17mm 2The spherical suction pipe device produces an annual output of ultrafine barium sulfate. As shown in Table 4:

[0070] Table 4. Impact of the reactor on the annual production of ultrafine barium sulfate

[0071]

[0072] Compared to a microreactor, the feed cross-sectional area is 10.17 mm². 2 The spherical exhaust pipe has increased the processing capacity by 30 times, and the annual output of ultrafine barium sulfate produced is 30 times that of before.

[0073] Moreover, the feed cross-sectional area is 10.17mm. 2 The BaSO4 particles prepared by the spherical extraction tube are smaller and have a narrower particle size distribution compared to the barium sulfate produced by Foshan Anyi Ultrafine Materials Co., Ltd. and Xinji Yudong Chemical Plant. Specific results can be found in [link to relevant documentation]. Figure 2 (a) and Figure 2 (b);

[0074] The ultrafine BaSO4 particles obtained under optimal conditions in this embodiment are compared with the ultrafine BaSO4 particles prepared by Hebei University of Science and Technology, specifically as follows: Figure 3 As shown in the comparison, the particle quality of this embodiment is also better, with smaller particle size, better particle uniformity, and narrower particle size distribution.

[0075] In summary, a feed cross-sectional area of ​​10.17 mm² is adopted. 2 With a spherical exhaust pipe, when the concentration of the reactant is 1.2 mol / L and the feed flow rate of the reactant is 10.42 m / s, ultrafine barium sulfate with a minimum particle size of 28.17 nm can be produced.

[0076] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0077] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing ultrafine barium sulfate, characterized in that: Includes the following steps: S1. At room temperature, weigh out appropriate amounts of industrial-grade barium chloride and industrial-grade sodium sulfate solid, add water to prepare barium chloride solution and sodium sulfate solution with equal molar concentrations, filter out impurities and then put them into barium chloride solution storage tank and sodium sulfate solution storage tank respectively. S2. Then, adjust the flow rate of the diaphragm metering pump connected to the barium chloride solution storage tank and the sodium sulfate solution storage tank to 2.25L-500L / h respectively to provide a stable pressure environment. Then, turn the opening of the diaphragm metering pump knob to adjust the two solutions to the same stable flow rate so that the two solutions flow out of the storage tank at the set flow rate. S3. The two liquids flowing out of the storage tank simultaneously enter the spherical exhaust pipe, where they undergo a rapid precipitation reaction to generate an emulsion containing ultrafine barium sulfate particles. The emulsion is then placed in the product storage tank. S4. Finally, the emulsion is centrifuged, filtered, washed with water, and centrifuged and filtered again to obtain an ultrafine barium sulfate filter cake, thus completing the preparation.

2. The method for preparing ultrafine barium sulfate according to claim 1, characterized in that, The concentrations of the barium chloride solution and sodium sulfate solution are set between 0.1 and 2.4 mol / L.

3. The method for preparing ultrafine barium sulfate according to claim 1, characterized in that, The feed cross-sectional area of ​​the spherical suction pipe is 10.17 mm². 2 .

4. The method for preparing ultrafine barium sulfate according to claim 1, characterized in that, The flow rate is set between 3.47 and 20.83 m / s.

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