Preparation method of electronic-grade barium carbonate

Abstract

The invention relates to the technical field of barium carbonate, and particularly provides a preparation method of electronic-grade barium carbonate, which comprises the following steps: mixing a barium salt solution with a carbonate solution for double decomposition reaction; in the metathesis reaction process, the pH value of the reaction system is periodically adjusted to fluctuate in the range of 6.0-9.0, the one-time fluctuation period is 10-60 min, the fluctuation cycle is not less than 2 times, and the one-time fluctuation is the process that the pH value is adjusted to the maximum value from the minimum value and then adjusted to the minimum value; and after the reaction is finished, carrying out solid-liquid separation, washing and drying to obtain the electronic-grade barium carbonate. According to the method, a dynamic pH oscillation mode is adopted, the purity and morphology control level of electronic-grade barium carbonate are remarkably improved, dynamic pH fluctuation interferes crystal nucleuses without growth, the crystal nucleuses are easier to form crystalline spherical or cubic particles, the size concentration degree is higher, extra impurities are basically not introduced, the post-treatment steps are simple and efficient, and the method is suitable for industrial production. Good application prospects are realized.

Description

Technical Field

[0001] The invention relates to the technical field of barium carbonate, and in particular to a method for preparing electronic-grade barium carbonate. Background Art

[0002] Electronic-grade barium carbonate has extremely high purity requirements, and impurities such as Fe, Ca, and Sr need to be controlled to the ppm level. Traditional processes are difficult to meet the above requirements due to problems such as insufficient raw material purity, introduction of impurities during the reaction process, and incomplete washing.

[0003] Some electronic components, such as MLCC, require barium carbonate particles to be spherical or nearly spherical, and have a narrow particle size distribution. The traditional carbonization method easily produces rod-shaped particles, and the particle size distribution is also relatively wide, which leads to unstable dielectric properties. In order to solve these technical problems, the prior art has also adopted some different improvement schemes, such as multi-stage crystallization, ion exchange or fluoride salt impurity removal, etc., but these methods will not only increase production costs, make the preparation steps more complicated, but also may introduce new impurities. In some schemes, deionized water will be used for multiple rinses and complexing agents will be added to achieve the removal of metal impurity residues, but this will introduce new organic impurities. If fluoride salts can be used to precipitate impurity ions, fluoride ion pollution will be introduced, and conventional morphology control additives, such as surfactants, are generally unable to carry out directional regulation of crystal surface growth, resulting in difficult to control particle morphology.

[0004] Based on this, how to optimize the preparation process so that impurities can be controlled more efficiently has become one of the technical problems that need to be solved urgently. Summary of the invention

[0005] In view of this, the present invention proposes a method for preparing electronic grade barium carbonate, which enhances the desorption of impurities and improves the purity by oscillating pH.

[0006] The technical solution of the present invention is achieved as follows: The present invention provides a method for preparing electronic grade barium carbonate, comprising the following steps: Step 1: mixing a barium salt solution with a carbonate solution to perform a double decomposition reaction; Step 2: During the double decomposition reaction, the pH value of the reaction system is periodically adjusted to fluctuate within the range of 6.0-9.0, with a fluctuation period of 10-60 minutes, and the number of fluctuation cycles is not less than 2 times. One fluctuation is the process of adjusting the pH from the lowest value to the highest value and then adjusting it to the lowest value; Step 3: After the reaction is completed, the solid and liquid are separated, washed and dried to obtain electronic grade barium carbonate.

[0007] In the prior art, a constant pH condition is mostly adopted, and crystal nuclei grow disorderly in this environment. Through pH fluctuation, the above-mentioned embodiment changes the charge on the particle surface, enhances the electrostatic repulsion force, prevents particle agglomeration, and the acid-base colloid environment can interfere with the crystal plane growth rate, forcing the particles to be oriented and arranged into spheres or cubes.

[0008] In some embodiments, in step two, before adjusting the pH, a crystal form control agent is further added. The crystal form control agent is at least one of a surfactant and an ionic liquid, and the addition amount is 0.1-5% of the total mass of the reaction solution.

[0009] In the above-mentioned embodiment, the surfactant or ionic liquid can regulate the growth interface energy of crystal nuclei by adsorbing on the particle surface. The surfactant can reduce the surface tension through physical adsorption, inhibit particle agglomeration, and thus further reduce the particle size. The ionic liquid can selectively regulate the growth of crystal planes through chemical bonding to achieve morphology regulation.

[0010] In some embodiments, the crystal form control agent is a bipolar ionic liquid, including a complex system of Bronsted acidic ionic liquid and bisulfate ionic liquid. The molar ratio of Bronsted acidic ionic liquid to bisulfate ionic liquid is 1:(1-3).

[0011] The dihydrogen phosphate in the Bronsted acidic ionic liquid can release protons, thereby complexing metal impurities such as iron ions, reducing lattice defects. The bisulfate in the bisulfate ionic liquid adsorbs on the (110) crystal plane through strong coordination ability to inhibit its growth. The two work together to increase the proportion of the (104) crystal plane, and the content of impurity ions and the like decreases significantly.

[0012] In some embodiments, the Bronsted acidic ionic liquid is 1-butyl-3-methylimidazolium dihydrogen phosphate, and the bisulfate ionic liquid is 1-butyl-3-methylimidazolium bisulfate.

[0013] As a specifically implementable and verified compound system with good effects, the acidic anion (H2PO4 - ) preferentially adsorbs on the high-energy crystal plane (such as (104)), inhibits its growth, promotes the exposure of low-energy crystal planes, and HSO4 - stabilizes the particle surface through electrostatic interaction to prevent disordered agglomeration. After compounding, a significant optimization of the particle size distribution can be achieved.

[0014] In some embodiments, in step two, the pH value fluctuates in the range of 6.5-8.5.

[0015] The lower limit of pH is set to 6.5 to avoid excessive acidity leading to Ba 2+Dissolution: The upper limit of pH is set to 8.5 to prevent the formation of Ba(OH)2 impurities due to excessive alkalinity. The narrow-range fluctuation reduces D50 and improves purity.

[0016] In some embodiments, in step two, the primary fluctuation period is 15 - 30 min, and the number of fluctuation cycles is 3 - 5 times.

[0017] The above-mentioned fluctuation period can match the crystal nucleation growth kinetics, and cycling 3 - 5 times ensures sufficient orientation control of crystal planes.

[0018] In some embodiments, the barium salt solution is a barium chloride solution. The barium salt solution is pretreated before mixing. The pretreatment method includes: adding citric acid or tartaric acid to the barium salt solution, with the addition amount being 0.05 - 0.2% of the mass of the barium salt, stirring for 30 - 60 min and then filtering to obtain a clarified barium salt solution.

[0019] The carboxylic acid group can complex with iron ions, calcium ions, etc. to form soluble complexes, which are removed by filtration. After pretreatment, the iron ion concentration in the raw material liquid is reduced, thereby reducing the purification pressure in subsequent processing.

[0020] In some embodiments, the washing in step three is gradient temperature washing, which sequentially uses hot water at 80 - 90 °C for washing once, warm water at 40 - 50 °C for washing once, and cold water at 20 - 30 °C for washing once. The amount of washing liquid used each time is 2 - 5 times the weight of the solid.

[0021] Gradient washing mainly enhances the removal effect of chloride ions and avoids particle dissolution.

[0022] In some embodiments, after solid-liquid separation in step three, the centrifugal mother liquor is recovered by vacuum distillation to recycle the bipolar ionic liquid.

[0023] Utilizing the low volatility characteristic of the ionic liquid, the recycling and reuse of the ionic liquid can be realized, reducing the use cost of additives.

[0024] In some embodiments, in step two, the temperature of the double decomposition reaction is 25 - 40 °C. When adjusting the pH, the reaction temperature is adjusted synchronously. The reaction temperature at the highest pH value is 5 - 10 °C higher than the reaction temperature at the lowest pH value.

[0025] When using pH oscillation, the static reaction equilibrium is broken to inhibit disordered growth. While oscillating, the reaction temperature is correspondingly fine-tuned. For example, during the pH rising stage, increasing the temperature is beneficial to accelerating crystal nucleation and enhancing the adsorption efficiency of the ionic liquid. While during the pH falling stage, decreasing the temperature can slow down the growth rate and extend the time window for morphology control.

[0026] The present invention has the following beneficial effects compared with the prior art: This application adopts the method of dynamic pH oscillation, significantly improving the purity and morphology control level of electronic-grade barium carbonate. The dynamic pH fluctuation interferes with the growth of crystal nuclei, making it easier for crystal nuclei to form crystalline spherical or cubic particles with a higher size concentration, which can meet the stringent requirements of dielectric materials for uniformity. Moreover, this preparation method is simpler, basically does not introduce additional impurities, and the post-treatment steps are simple and efficient, having good application prospects. Detailed implementation mode

[0027] The following will describe clearly and completely the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0028] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the embodiments of the present invention belong. If the definitions stated in this part are contrary to or inconsistent with the definitions stated in the patents, patent applications, published patent applications and other publications incorporated herein by reference, the definitions listed in this part shall prevail over the definitions incorporated herein by reference.

[0029] Unless otherwise specified, the methods used in the following examples are all conventional methods. The materials, reagents and instruments used, unless otherwise specified, are all conventional materials, reagents and instruments in this field, and those skilled in the art can obtain them through commercial channels.

[0030] When an equivalent, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper limit preferred values and lower limit preferred values, it should be understood that all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value are specifically disclosed, regardless of whether the range is separately disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this application, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range. In the specification and claims of this application, range limitations can be combined and / or interchanged, and if not otherwise stated, these ranges include all sub-ranges contained therein.

[0031] Example 1 This example provides a method for preparing barium carbonate under pH oscillation conditions Raw material treatment: Industrial-grade barium chloride (BaCl₂·2H₂O with a purity of 98%) is dissolved in deionized water to prepare an aqueous solution with a concentration of 25 wt%.

[0032] Double decomposition preparation: The barium chloride aqueous solution and the ammonium carbonate solution with a concentration of 20 wt% are mixed according to a molar ratio of barium chloride to ammonium carbonate of 1:1; The initial pH of the mixed solution is adjusted to 6.0 with ammonia water (5 wt%) and dilute hydrochloric acid (0.1 mol / L), and the temperature is 30 °C. Then, within 15 minutes, the pH is adjusted from 6.0 to 9.0, and then adjusted back to 6.0. This step is repeated 3 times; Centrifugal separation is carried out. The filter cake is washed 3 times with cold water at 25 °C and dried to obtain barium carbonate.

[0033] Example 2 This example provides a method for preparing barium carbonate using pH oscillation conditions in combination with a surfactant Raw material treatment: Industrial-grade barium chloride (BaCl₂·2H₂O with a purity of 98%) is dissolved in deionized water to prepare an aqueous solution with a concentration of 25 wt%.

[0034] Double decomposition preparation: The barium chloride aqueous solution and the ammonium carbonate solution with a concentration of 20 wt% are mixed according to a molar ratio of barium chloride to ammonium carbonate of 1:1, and then 0.8 wt% of sodium hexametaphosphate is added to the mixed solution; The initial pH of the mixed solution is adjusted to 6.0 with ammonia water (5 wt%) and dilute hydrochloric acid (0.1 mol / L), and the temperature is 30 °C. Then, within 15 minutes, the pH is adjusted from 6.0 to 9.0, and then adjusted back to 6.0. This step is repeated 3 times; Centrifugal separation is carried out. The filter cake is washed 3 times with cold water at 25 °C and dried to obtain barium carbonate.

[0035] Example 3 This example provides a method for preparing barium carbonate using pH oscillation conditions in combination with a bipolar ionic liquid complex system Raw material treatment: Industrial-grade barium chloride (BaCl₂·2H₂O with a purity of 98%) is dissolved in deionized water to prepare an aqueous solution with a concentration of 25 wt%.

[0036] Double decomposition preparation: The barium chloride aqueous solution and the ammonium carbonate solution with a concentration of 20 wt% are mixed according to a molar ratio of barium chloride to ammonium carbonate of 1:1, and then 0.8 wt% of a bipolar ionic liquid is added to the mixed solution. The bipolar ionic liquid is obtained by mixing 1-butyl-3-methylimidazolium dihydrogen phosphate and 1-butyl-3-methylimidazolium hydrogen sulfate according to a molar ratio of 1:2; Adjust the initial pH of the mixed solution to 6.0 with ammonia water (5 wt%) and dilute hydrochloric acid (0.1 mol / L), keep the temperature at 30 °C, then adjust the pH from 6.0 to 9.0 within 15 min, and then adjust it back to 6.0. Repeat this step 3 times; Centrifuge and separate, wash the filter cake 3 times with cold water at 25 °C, and dry to obtain barium carbonate.

[0037] Example 4 This example provides a method for preparing barium carbonate using a pH oscillation condition in combination with a binary ionic liquid complex system Raw material treatment: Dissolve industrial-grade barium chloride (BaCl2·2H2O purity 98%) in deionized water to prepare an aqueous solution with a concentration of 25 wt%.

[0038] Double decomposition preparation: Mix the barium chloride aqueous solution and the ammonium carbonate solution with a concentration of 20 wt% according to a molar ratio of barium chloride to ammonium carbonate of 1:1, and then add 0.8 wt% of the binary ionic liquid to the mixed solution. The binary ionic liquid is obtained by mixing 1-butyl-3-methylimidazolium dihydrogen phosphate and 1-butyl-3-methylimidazolium hydrogen sulfate according to a molar ratio of 1:2; Adjust the initial pH of the mixed solution to 6.5 with ammonia water (5 wt%) and dilute hydrochloric acid (0.1 mol / L), keep the temperature at 30 °C, then adjust the pH from 6.5 to 8.5 within 15 min, and then adjust it back to 6.5. Repeat this step 3 times; Centrifuge and separate, wash the filter cake 3 times with cold water at 25 °C, and dry to obtain barium carbonate.

[0039] Example 5 This example provides a method for preparing barium carbonate using a pH oscillation condition in combination with a binary ionic liquid complex system Raw material treatment: Dissolve industrial-grade barium chloride (BaCl2·2H2O purity 98%) in deionized water to prepare an aqueous solution with a concentration of 25 wt%, then add 0.1 wt% citric acid, stir for 45 min and then filter, with the conductivity lower than 100 μS / cm.

[0040] Double decomposition preparation: Mix the purified barium chloride aqueous solution and the ammonium carbonate solution with a concentration of 20 wt% according to a molar ratio of barium chloride to ammonium carbonate of 1:1, and then add 0.8 wt% of the binary ionic liquid to the mixed solution. The binary ionic liquid is obtained by mixing 1-butyl-3-methylimidazolium dihydrogen phosphate and 1-butyl-3-methylimidazolium hydrogen sulfate according to a molar ratio of 1:2; Adjust the initial pH of the mixed solution to 6.5 with ammonia water (5 wt%) and dilute hydrochloric acid (0.1 mol / L) at a temperature of 25 °C. Then, within 15 minutes, adjust the pH from 6.5 to 8.5 while heating the temperature to 35 °C at a rate of 1 °C / min. Then adjust it back to 6.5 and cool the temperature to 25 °C at a rate of 1 °C / min. Repeat this step 3 times; Centrifuge and separate, wash the filter cake 3 times with cold water at 25 °C, and dry to obtain barium carbonate.

[0041] Example 6 This example provides a method for preparing barium carbonate using a pH oscillation condition in combination with a binary ionic liquid complex system. Raw material treatment: Dissolve industrial-grade barium chloride (BaCl2·2H2O purity 98%) in deionized water to prepare an aqueous solution with a concentration of 25 wt%. Then add 0.1 wt% citric acid, stir for 45 minutes, and filter. The conductivity is lower than 100 μS / cm.

[0042] Double decomposition preparation: Mix the purified aqueous barium chloride solution with an ammonium carbonate solution with a concentration of 20 wt% according to a molar ratio of barium chloride to ammonium carbonate of 1:1. Then add 0.8 wt% of the binary ionic liquid to the mixed solution. The binary ionic liquid is obtained by mixing 1-butyl-3-methylimidazolium dihydrogen phosphate and 1-butyl-3-methylimidazolium hydrogen sulfate according to a molar ratio of 1:2; Adjust the initial pH of the mixed solution to 6.5 with ammonia water (5 wt%) and dilute hydrochloric acid (0.1 mol / L) at a temperature of 25 °C. Then, within 15 minutes, adjust the pH from 6.5 to 8.5 while slowly heating the temperature to 35 °C simultaneously. Then adjust it back to 6.5 and cool the temperature to 25 °C simultaneously. Repeat this step 3 times; Centrifuge and separate, wash the filter cake once with hot water at 80 °C, then once with warm water at 45 °C, and then once with cold water at 25 °C, and dry to obtain barium carbonate. The filtrate is recovered by vacuum distillation at 60 °C and -0.09 MPa.

[0043] Example 7 This example provides a method for preparing barium carbonate using a pH oscillation condition in combination with a binary ionic liquid complex system. Raw material treatment: Dissolve industrial-grade barium chloride (BaCl2·2H2O purity 98%) in deionized water to prepare an aqueous solution with a concentration of 25 wt%.

[0044] Double decomposition preparation: Mix an aqueous barium chloride solution with an ammonium carbonate solution with a concentration of 20 wt%, with a molar ratio of barium chloride to ammonium carbonate of 1:1. Then add 0.8 wt% of a bipolar ionic liquid to the mixed solution. The bipolar ionic liquid is obtained by mixing 1-butyl-3-methylimidazolium dihydrogen phosphate and 1-butyl-3-methylimidazolium hydrogen sulfate in a molar ratio of 1:1. Adjust the initial pH of the mixed solution to 6.0 with ammonia water (5 wt%) and dilute hydrochloric acid (0.1 mol / L) at a temperature of 30 °C. Then, within 15 minutes, adjust the pH from 6.0 to 9.0, and then back to 6.0. Repeat this step 3 times. Centrifuge and separate, wash the filter cake 3 times with cold water at 25 °C, and dry to obtain barium carbonate.

[0045] Example 8 This example provides a method for preparing barium carbonate using a pH oscillation condition in combination with a bipolar ionic liquid complex system. Raw material treatment: Dissolve industrial-grade barium chloride (BaCl₂·2H₂O purity 98%) in deionized water to prepare an aqueous solution with a concentration of 25 wt%.

[0046] Double decomposition preparation: Mix an aqueous barium chloride solution with an ammonium carbonate solution with a concentration of 20 wt%, with a molar ratio of barium chloride to ammonium carbonate of 1:1. Then add 0.8 wt% of a bipolar ionic liquid to the mixed solution. The bipolar ionic liquid is obtained by mixing 1-butyl-3-methylimidazolium dihydrogen phosphate and 1-butyl-3-methylimidazolium hydrogen sulfate in a molar ratio of 1:3. Adjust the initial pH of the mixed solution to 6.0 with ammonia water (5 wt%) and dilute hydrochloric acid (0.1 mol / L) at a temperature of 30 °C. Then, within 15 minutes, adjust the pH from 6.0 to 9.0, and then back to 6.0. Repeat this step 3 times. Centrifuge and separate, wash the filter cake 3 times with cold water at 25 °C, and dry to obtain barium carbonate.

[0047] Comparative Example 1 This comparative example uses a conventional double decomposition reaction technical solution with a constant pH condition of 8.0 for the double decomposition reaction.

[0048] Raw material treatment: Dissolve industrial-grade barium chloride (BaCl₂·2H₂O purity 98%) in deionized water to prepare an aqueous solution with a concentration of 25 wt%.

[0049] Double decomposition preparation: Mix an aqueous barium chloride solution with an ammonium carbonate solution with a concentration of 20 wt%, with a molar ratio of barium chloride to ammonium carbonate of 1:1. Adjust the initial pH of the mixed solution to 8.0 with ammonia water (5 wt%) and dilute hydrochloric acid (0.1 mol / L), keep the temperature at 30 °C, and carry out the reaction for 45 min with heat preservation; Centrifuge and separate, wash the filter cake 3 times with cold water at 25 °C, and dry to obtain barium carbonate.

[0050] Comparative Example 2 This comparative example adopts the technical scheme of conventional double decomposition reaction, and the double decomposition reaction is carried out under the condition that the pH is constantly 8.0, and sodium hexametaphosphate is fed.

[0051] Raw material treatment: Dissolve industrial-grade barium chloride (BaCl2·2H2O purity 98%) in deionized water to prepare an aqueous solution with a concentration of 25 wt%.

[0052] Double decomposition preparation: Mix the barium chloride aqueous solution with an ammonium carbonate solution with a concentration of 20 wt% according to the molar ratio of barium chloride to ammonium carbonate of 1:1, and then feed 0.8 wt% of sodium hexametaphosphate into the mixed solution; Adjust the initial pH of the mixed solution to 8.0 with ammonia water (5 wt%) and dilute hydrochloric acid (0.1 mol / L), keep the temperature at 30 °C, and carry out the reaction for 45 min with heat preservation; Centrifuge and separate, wash the filter cake 3 times with cold water at 25 °C, and dry to obtain barium carbonate.

[0053] Comparative Example 3 This comparative example provides a preparation method of barium carbonate using pH oscillation conditions in combination with ionic liquid Raw material treatment: Dissolve industrial-grade barium chloride (BaCl2·2H2O purity 98%) in deionized water to prepare an aqueous solution with a concentration of 25 wt%.

[0054] Double decomposition preparation: Mix the barium chloride aqueous solution with an ammonium carbonate solution with a concentration of 20 wt% according to the molar ratio of barium chloride to ammonium carbonate of 1:1, and then add 0.8 wt% of ionic liquid to the mixed solution. The ionic liquid is 1-butyl-3-methylimidazolium dihydrogen phosphate; Adjust the initial pH of the mixed solution to 6.0 with ammonia water (5 wt%) and dilute hydrochloric acid (0.1 mol / L), keep the temperature at 30 °C, and then adjust the pH from 6.0 to 9.0 within 15 min, and then adjust it to 6.0 again, and repeat this step 3 times; Centrifuge and separate, wash the filter cake 3 times with cold water at 25 °C, and dry to obtain barium carbonate.

[0055] Comparative Example 4 This comparative example provides a preparation method of barium carbonate using pH oscillation conditions in combination with ionic liquid Raw material treatment: Industrial-grade barium chloride (BaCl₂·2H₂O with a purity of 98%) is dissolved in deionized water to prepare an aqueous solution with a concentration of 25 wt%.

[0056] Double decomposition preparation: An aqueous solution of barium chloride and an ammonium carbonate solution with a concentration of 20 wt% are mixed according to a molar ratio of barium chloride to ammonium carbonate of 1:1. Then, 0.8 wt% of an ionic liquid is added to the mixed solution. The ionic liquid is 1-butyl-3-methylimidazolium hydrogen sulfate; The initial pH of the mixed solution is adjusted to 6.0 with ammonia water (5 wt%) and dilute hydrochloric acid (0.1 mol / L) at a temperature of 30 °C. Then, within 15 minutes, the pH is adjusted from 6.0 to 9.0 and then back to 6.0, and this step is repeated 3 times; Centrifugal separation is carried out. The filter cake is washed 3 times with cold water at 25 °C and dried to obtain barium carbonate. The D50, D90 / D10, and impurity ion detections are carried out on the barium carbonate prepared in the above examples and comparative examples respectively, and the following data are obtained:

[0057] After Example 4 adopted a more preferable pH value range compared with Example 3, its D50 particle size was smaller, indicating that the narrow-range pH fluctuation reduced particle dissolution and secondary nucleation, improving the morphological uniformity. And the iron ion content decreased from 10 ppm to 8 ppm, indicating that when the pH fluctuation range is too large, there may be dissolution of barium ions, resulting in an increase in adsorbed impurities. In Example 5, while adjusting the pH, the temperature was also fluctuated. The heating stage may promote the diffusion of the ionic liquid and improve the adsorption efficiency, while the cooling stage extended the control time of the crystal plane, thus being beneficial to the increase in the proportion of the (104) crystal plane. After gradient washing in Example 6, not only the D50 particle size was reduced, but also the proportion of the (104) crystal plane increased. At the same time, the contents of various impurity components decreased significantly. And when the recycled ionic liquid was used for secondary production and recycled 5 times, its recovery rate was still above 90%, and the D50 particle size fluctuation of the prepared product was ≤0.02 μm, which had significant economic value.

[0058] The above is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of electronic grade barium carbonate, characterized in that, It includes the following steps: Step 1: Mix the barium salt solution with the carbonate solution to conduct a double decomposition reaction; Step 2: During the double decomposition reaction, periodically adjust the pH value of the reaction system to fluctuate within the range of 6.0 - 9.

0. The period of one fluctuation is 10 - 60 min, and the number of fluctuation cycles is not less than 2. One fluctuation is a process of adjusting the pH from the lowest value to the highest value and then back to the lowest value; Step 3: After the reaction ends, perform solid - liquid separation, wash and dry to obtain electronic - grade barium carbonate.

2. The preparation method of electronic-grade barium carbonate according to claim 1, characterized in that, In Step 2, before adjusting the pH, it also includes adding a crystal form control agent, and the crystal form control agent is at least one of a surfactant and an ionic liquid, and the addition amount is 0.1 - 5% of the total mass of the reaction solution.

3. The preparation method of electronic grade barium carbonate according to claim 2, characterized in that, The crystal form control agent is a bipolar ionic liquid, including a complex system of Bronsted acidic ionic liquid and bisulfate ionic liquid, and the molar ratio of Bronsted acidic ionic liquid to bisulfate ionic liquid is 1:(1 - 3).

4. The preparation method of electronic-grade barium carbonate according to claim 3, characterized in that, The Bronsted acidic ionic liquid is 1 - butyl - 3 - methylimidazolium dihydrogen phosphate, and the bisulfate ionic liquid is 1 - butyl - 3 - methylimidazolium bisulfate.

5. The preparation method of electronic grade barium carbonate according to claim 1, characterized in that, In Step 2, the pH value fluctuation range is 6.5 - 8.

5.

6. The preparation method of electronic grade barium carbonate according to claim 1, characterized in that, In Step 2, the period of one fluctuation is 15 - 30 min, and the number of fluctuation cycles is 3 - 5 times.

7. The preparation method of electronic-grade barium carbonate according to claim 1, characterized in that, The barium salt solution is a barium chloride solution. The barium salt solution is pretreated before mixing. The pretreatment method includes: adding citric acid or tartaric acid to the barium salt solution, and the addition amount is 0.05 - 0.2% of the barium salt mass. After stirring for 30 - 60 min, filter to obtain a clarified barium salt solution.

8. The preparation method of electronic-grade barium carbonate according to claim 1, characterized in that, The washing in Step 3 is gradient - temperature washing, successively washing with hot water at 80 - 90 °C for 1 time, warm water at 40 - 50 °C for 1 time, and cold water at 20 - 30 °C for 1 time. The amount of each washing liquid used is 2 - 5 times the weight of the solid.

9. The preparation method of electronic-grade barium carbonate according to any one of claims 3-6, characterized in that, After solid - liquid separation in Step 3, the centrifugation mother liquor is recovered by vacuum distillation to obtain the bipolar ionic liquid.

10. The preparation method of electronic grade barium carbonate according to claim 1, characterized in that, In Step 2, the temperature of the double decomposition reaction is 25 - 40 °C. When adjusting the pH, synchronously adjust the reaction temperature, and the reaction temperature at the highest pH value is 5 - 10 °C higher than the reaction temperature at the lowest pH value.

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