Purification method for improving purity of bentonite

Abstract

The invention relates to the field of non-metallic mineral materials, in particular to a purification method for improving the purity of bentonite. Raw ore is subjected to crushing pretreatment, so that the particle size of the raw ore can pass through a 200-mesh screen, and sufficient subsequent reaction is ensured. Then, the crushed bentonite powder and deionized water are fully mixed according to the solid-to-liquid ratio of 1: 8, and uniform and stable initial slurry is formed; and on the basis of the slurry, sequentially executing a core purification step, ultrasonic and chemical impurity removal, stepped sedimentation, low-temperature gradient centrifugation, targeted iron removal and dehydration drying to obtain a high-purity and high-whiteness bentonite concentrate product. Compared with a traditional process, the method designed by the invention has the advantages that the purification period is greatly shortened, the total amount of the required dispersing agent is remarkably reduced, nanoscale impurities are efficiently removed, particularly, iron impurities which are difficult to treat also have an excellent removal effect, equipment required by the whole process flow is high in universality, a special device is not needed, and the method is suitable for industrial production. And the comprehensive production cost is effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of non-metallic mineral materials, in particular to a purification method for improving the purity of bentonite. BACKGROUND

[0002] In the field of non-metallic mineral materials, the existing methods in the purification technology of bentonite generally face the bottleneck problem that the purification efficiency and product quality are difficult to balance. The traditional process often leads to a long overall purification period due to a long sedimentation process (such as relying on natural sedimentation), which significantly restricts the production efficiency. At the same time, in order to achieve effective dispersion and impurity separation, a high amount of chemical dispersant is often needed, which not only increases the cost of raw materials, but also may introduce new impurities or affect the performance of the product. More importantly, for nanoscale impurities with extremely small particle size and iron impurities existing in the internal structure of the montmorillonite crystal lattice, the conventional physical separation or chemical treatment methods have significant limitations: physical methods are difficult to effectively remove nanoscale impurities, while chemical treatment may remove part of the impurities, but it is easy to damage the layered structure of montmorillonite or the removal effect of impurity iron is not good, resulting in limited improvement of the purity of the final product (especially the content of montmorillonite) and unsatisfactory whiteness. In addition, some optimized processes rely on multiple centrifugation or special equipment, which may improve the purity, but bring problems such as complex operation, high energy consumption, large equipment investment, and high comprehensive cost. Therefore, it is urgent to develop a new purification method for bentonite that is efficient, low-cost, can deeply remove various impurities (especially nanoscale impurities and impurity iron), and does not damage the structure of montmorillonite. SUMMARY

[0003] Based on the problems existing in the above background technology, the present application proposes a purification method for improving the purity of bentonite, the steps are as follows,

[0004] Step 1: pretreat the bentonite, place the bentonite ore in a crushing device for crushing treatment until the particle size can pass through a 200 mesh screen, and fully stir and mix the sieved bentonite with a certain proportion of deionized water to form a uniform and stable slurry;

[0005] Step 2: ultrasonic-assisted chemical impurity removal is performed on the slurry obtained in step 1, a certain concentration of hydrochloric acid is added to the slurry after starting the ultrasonic generator, and the supernatant is carefully poured after reacting at a certain temperature for a period of time; the cavitation effect of ultrasonic waves can produce local high temperature and high pressure, accelerate the chemical reaction, and make the carbonates and hydrochloric acid react fully, thereby effectively removing the carbonate impurities in the bentonite;

[0006] Step 3: re-add deionized water to step 2, then add a certain concentration of hydrogen peroxide, start the ultrasonic generator, remove the supernatant after a certain temperature and time; under the action of ultrasonic waves, hydrogen peroxide can more effectively oxidize and decompose the organic matter in bentonite, converting it into a substance that is easily soluble in water, thereby achieving the purpose of removing organic matter;

[0007] Step 4: the slurry after removing the supernatant in step 3 is placed at a certain temperature for a period of time for a first settling, then the temperature is lowered again for a period of time for a second settling, and the upper suspension is extracted by siphon after the settling is completed; through this step-by-step settling method, the settling efficiency can be significantly improved, compared with the traditional settling method, the settling efficiency is greatly improved, and a purer suspension is obtained;

[0008] Step 5: the upper suspension extracted in step 4 is placed in a centrifuge, the speed and temperature are set for the first centrifugation operation, and part of the impurities and larger particles are separated; the centrifugal speed is further increased and the second centrifugation operation is performed again to remove the precipitate after centrifugation and retain the supernatant;

[0009] Step 6: add a certain concentration of sodium dithionite to the supernatant obtained in step 5 and stir, and after a period of reaction, the supernatant is transferred to a centrifuge for centrifugal dewatering; as a reducing agent, sodium dithionite can chemically react with iron impurities in bentonite to reduce them to soluble iron ions, thereby removing them from bentonite. This targeted iron removal step can significantly reduce the iron content of bentonite and improve its whiteness and purity;

[0010] Step 7: the material after centrifugation in step 6 is placed in a drying device, completely dried and ground to pass through a 325 mesh screen, and a uniform particle size, high purity bentonite product is obtained.

[0011] Preferably, in step 1, the bentonite is mixed with deionized water at a mass ratio of 1:7-1:9, and the stirring time is 25-35 minutes.

[0012] Preferably, in step 2, the concentration of hydrochloric acid added is 0.4-0.6wt%, the ultrasonic frequency is 20-30kHz, the ultrasonic power is 250-350W, the reaction time is 50-70 minutes, and the reaction temperature is 30-50℃.

[0013] Preferably, in step 3, the concentration of hydrogen peroxide added is 0.4-0.6wt%, the ultrasonic frequency is 20-30kHz, the ultrasonic power is 250-350W, the reaction time is 50-70 minutes, and the reaction temperature is 30-50℃.

[0014] Preferably, in step 4, the temperature during the first settling is 40-60℃, the time for the first settling is 20-40 minutes, the temperature during the second settling is 25-35℃, and the time for the second settling is 20-40 minutes.

[0015] Preferably, in step 5, the centrifugal speed during the first separation is 1000-2000r / min, the temperature is 20-30℃, and the centrifugal time is 1-5 minutes; the centrifugal speed during the second separation is 2000-3000r / min, the temperature is 5-15℃, and the centrifugal time is 4-6 minutes.

[0016] Preferably, in step 6, the concentration of sodium hydrosulfite is 0.08-0.12wt%, the temperature during the reaction is 30-50℃, the reaction time is 20-40 minutes, the centrifugal speed during the centrifugal operation is 4500-5500r / min, and the centrifugal time is 10-20 minutes.

[0017] Preferably, in step 7, the temperature in the drying equipment is set to 100-110℃.

[0018] Compared with the prior art, the beneficial effects of the present application are: 1) through the ultrasonic cavitation effect and chemical reagents, the physical stripping of nanoscale particles is significantly enhanced while efficiently stripping carbonate and organic impurities, overcoming the bottleneck that traditional physical methods cannot remove nanoscale impurities; by using the selective reduction of sodium hydrosulfite on iron, the stubborn iron impurities are efficiently dissolved without damaging the structure of montmorillonite, thereby improving the whiteness and chemical purity of the product from the root.

[0019] 2) The step-by-step settling process precisely controls the temperature to optimize the particle settling kinetics, making the settling efficiency several times higher than natural settling, and completely solving the core pain point of long settling time in traditional processes; gradient centrifugation combined with low-temperature inhibition of agglomeration effect realizes deep separation of nanoscale impurities in only two stages of centrifugation, avoiding the complex operation and energy waste of multiple centrifugations.

[0020] 3) The integrity of the montmorillonite structure is protected throughout the process (gentle stripping by ultrasound + low-temperature centrifugation), and the purity of the final product is stable at ≥95%, far exceeding the expected purity of low-grade ore purification; the whole process is based on common equipment such as crushers, ultrasonic devices, and conventional centrifuges, without the need for expensive special devices, greatly reducing the industrialization threshold; the obtained bentonite has high purity (nanoscale impurities remaining <0.5%), high whiteness (iron impurity removal rate >92%), and uniform particle size (passing through a 325 mesh sieve), meeting the application requirements of high-end non-metallic materials. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below with 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 the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0022] Embodiment 1

[0023] A purification method for improving the purity of bentonite, the steps are as follows,

[0024] Step 1: The bentonite is pretreated, the bentonite ore is placed in a crushing device for crushing treatment until the particle size can pass through a 200-mesh screen, and the screened bentonite is fully stirred and mixed with deionized water at a mass ratio of 1:8, and the stirring time is 30 minutes to form a uniform and stable slurry;

[0025] Step 2: The slurry obtained in step 1 is subjected to ultrasonic-assisted chemical impurity removal, a hydrochloric acid solution with a concentration of 0.5wt% is added to the slurry after starting an ultrasonic generator (ultrasonic frequency is 25 kHz, ultrasonic power is 300 W), and the supernatant is carefully poured after reaction at 40℃ for 60 minutes;

[0026] Step 3: Deionized water is added to step 2, and then a hydrogen peroxide solution with a concentration of 0.5wt% is added, and an ultrasonic generator (ultrasonic frequency is 25 kHz, ultrasonic power is 300 W) is started, and the supernatant is removed after reaction at 40℃ for 60 minutes;

[0027] Step 4: The slurry after removing the supernatant in step 3 is placed at 50℃ for 30 minutes for first sedimentation, and then the temperature is reduced to 30℃ for 30 minutes for second sedimentation, and the upper suspension is extracted by siphon after sedimentation;

[0028] Step 5: The upper suspension extracted in step 4 is placed in a centrifuge, and the first centrifugation operation is performed at a speed of 1500r / min and a temperature of 25℃ for 3 minutes to separate part of the impurities and larger particles; the centrifugal speed is further increased to 2500r / min and the temperature is reduced to 10℃, and the second centrifugation operation is performed again for 5 minutes, and the precipitate after centrifugation is removed, and the supernatant is reserved;

[0029] Step 6: A sodium dithionite solution with a concentration of 0.1wt% is added to the supernatant obtained in step 5 and stirred, and the supernatant is transferred to a centrifuge for centrifugal dewatering after reaction at 40℃ for 30 minutes; the centrifugal speed during centrifugation is 5000r / min, and the centrifugation time is 15 minutes;

[0030] Step 7: The material after centrifugation in step 6 is placed in a drying device with a drying temperature of 105°C. After complete drying, grinding is performed to pass through a 325 mesh screen, thereby obtaining a finished product of bentonite with uniform particle size and high purity.

[0031] After purification by the method of the present application, the montmorillonite content of the raw ore with a montmorillonite content of 35% is significantly increased to 96.2%, far exceeding the expected purification of medium and low grade ores; the residual amount of quartz impurities is sharply reduced from 22% to <0.5% (nanoscale quartz removal rate is more than 97.7%), completely solving the problem of residual fine particle impurities; the targeted removal rate of impurity iron reaches 92.3%, which can achieve efficient removal of iron elements in bentonite.

[0032] Example 2

[0033] A purification method for improving the purity of bentonite, the steps are as follows,

[0034] Step 1: The bentonite is pretreated. The bentonite ore is crushed in a crushing device until the particle size can pass through a 200 mesh screen. The sieved bentonite is thoroughly mixed with deionized water at a mass ratio of 1:7. The stirring time is 25 minutes to form a uniform and stable slurry;

[0035] Step 2: The slurry obtained in step 1 is subjected to ultrasonic assisted chemical impurity removal. After starting the ultrasonic generator (ultrasonic frequency is 20 kHz, ultrasonic power is 250 W), 0.4 wt% hydrochloric acid is added to the slurry. After reacting at 30°C for 50 minutes, the supernatant is carefully poured off;

[0036] Step 3: Deionized water is added to step 2, and then 0.4 wt% hydrogen peroxide is added. The ultrasonic generator (ultrasonic frequency is 20 kHz, ultrasonic power is 250 W) is started. After reacting at 30°C for 50 minutes, the supernatant is removed;

[0037] Step 4: The slurry after removing the supernatant in step 3 is placed at 40°C for 20 minutes for the first sedimentation, and then the temperature is reduced to 25°C for 20 minutes for the second sedimentation. After sedimentation, the upper suspension is extracted by siphon;

[0038] Step 5: The upper suspension extracted in step 4 is placed in a centrifuge, and the rotation speed is set to 1000 r / min and the temperature is set to 20°C for the first centrifugation operation for 1 minute to separate part of the impurities and larger particles. The centrifugal speed is further increased to 2000 r / min and the temperature is reduced to 5°C for the second centrifugation operation for 4 minutes. The precipitate after centrifugation is removed, and the supernatant is retained;

[0039] Step 6: Add sodium dithionite with a concentration of 0.08wt% to the supernatant obtained in step 5 and stir, after 20 minutes of reaction at 30°C, transfer the supernatant to a centrifuge for centrifugal dewatering, the centrifugal speed during centrifugation is 4500r / min, and the centrifugation time is 10 minutes;

[0040] Step 7: Place the material after centrifugation in step 6 in a drying device with a drying temperature of 100°C, after complete drying, grind it to pass through a 325 mesh screen, and the uniform particle size and high purity bentonite product is obtained.

[0041] Example 3

[0042] A purification method for improving the purity of bentonite, the steps are as follows,

[0043] Step 1: Pretreat the bentonite, place the bentonite ore in a crushing device for crushing treatment until the particle size can pass through a 200 mesh screen, mix the sieved bentonite with deionized water at a mass ratio of 1:9 by fully stirring, the stirring time is 35 minutes to form a uniform and stable slurry;

[0044] Step 2: Ultrasonic assisted chemical impurity removal is performed on the slurry obtained in step 1, after starting the ultrasonic generator (ultrasonic frequency is 30kHz, ultrasonic power is 350W), add hydrochloric acid with a concentration of 0.6wt% to the slurry, after 70 minutes of reaction at 50°C, carefully pour off the supernatant;

[0045] Step 3: Add deionized water to step 2 again, then add hydrogen peroxide with a concentration of 0.6wt%, start the ultrasonic generator (ultrasonic frequency is 30kHz, ultrasonic power is 350W), after 70 minutes of reaction at 50°C, remove the supernatant;

[0046] Step 4: Place the slurry after removing the supernatant in step 3 at 60°C for 40 minutes for the first sedimentation, then reduce the temperature to 35°C again and stand for 35 minutes for the second sedimentation, after sedimentation, extract the upper suspension by siphon;

[0047] Step 5: Place the upper suspension extracted in step 4 in a centrifuge, set the speed to 2000r / min and the temperature to 30°C for the first centrifugation operation for 5 minutes, separate part of the impurities and larger particles; further increase the centrifugal speed to 3000r / min and reduce the temperature to 15°C, then perform the second centrifugation operation for 6 minutes again, remove the precipitate after centrifugation, and retain the supernatant;

[0048] Step 6: Add sodium dithionite with a concentration of 0.12wt% to the supernatant obtained in step 5 and stir, after 40 minutes of reaction at 50°C, transfer the supernatant to a centrifuge for centrifugal dewatering, the centrifugal speed during centrifugation is 5500r / min, and the centrifugation time is 20 minutes;

[0049] Step 7: Place the material after centrifugation in step 6 in a drying device with a drying temperature of 110°C, after complete drying, grind it to pass through a 325 mesh screen, and the uniform particle size and high purity bentonite product is obtained.

[0050] Example 4

[0051] A purification method for improving the purity of bentonite, the steps are as follows,

[0052] Step 1: Pretreat the bentonite, place the bentonite ore in a crushing device for crushing treatment until the particle size can pass through a 200 mesh screen, mix the sieved bentonite with deionized water at a mass ratio of 1:8 by fully stirring, and the stirring time is 35 minutes to form a uniform and stable slurry;

[0053] Step 2: Ultrasonic assisted chemical impurity removal is performed on the slurry obtained in step 1, after starting the ultrasonic generator (ultrasonic frequency is 27kHz, ultrasonic power is 270W), add hydrochloric acid with a concentration of 0.5wt% to the slurry, after 55 minutes of reaction at 35°C, carefully pour off the supernatant;

[0054] Step 3: Add deionized water to step 2 again, then add hydrogen peroxide with a concentration of 0.5wt%, start the ultrasonic generator (ultrasonic frequency is 27kHz, ultrasonic power is 270W), after 55 minutes of reaction at 35°C, remove the supernatant;

[0055] Step 4: Place the slurry after removing the supernatant in step 3 at 45°C for 25 minutes for the first sedimentation, then reduce the temperature to 26°C again and stand for 25 minutes for the second sedimentation, after sedimentation, extract the upper suspension by siphon;

[0056] Step 5: Place the upper suspension extracted in step 4 in a centrifuge, set the speed to 1250r / min and the temperature to 22°C for the first centrifugation operation for 2 minutes, separate part of the impurities and larger particles; further increase the centrifugal speed to 2250r / min and reduce the temperature to 7°C, then perform the second centrifugation operation for 5 minutes, remove the precipitate after centrifugation, and retain the supernatant;

[0057] Step 6: Add sodium dithionite with a concentration of 0.09wt% to the supernatant obtained in step 5 and stir, after 25 minutes of reaction at 35℃, transfer the supernatant to a centrifuge for centrifugal dewatering, the centrifugal speed during centrifugation is 4650r / min, and the centrifugation time is 12 minutes;

[0058] Step 7: Place the material after centrifugation in step 6 in a drying device with a drying temperature of 103℃, after complete drying, grind it to pass through a 325 mesh screen, and the uniform particle size and high purity bentonite product is obtained.

[0059] Example 5

[0060] A purification method for improving the purity of bentonite, the steps are as follows,

[0061] Step 1: Pretreat the bentonite, place the bentonite ore in a crushing device for crushing treatment until the particle size can pass through a 200 mesh screen, mix the sieved bentonite with deionized water at a mass ratio of 1:7 by fully stirring, and the stirring time is 22 minutes to form a uniform and stable slurry;

[0062] Step 2: Ultrasonic assisted chemical impurity removal is performed on the slurry obtained in step 1, after starting the ultrasonic generator (ultrasonic frequency is 22kHz, ultrasonic power is 225W), add hydrochloric acid with a concentration of 0.4wt% to the slurry, after 65 minutes of reaction at 45℃, carefully pour off the supernatant;

[0063] Step 3: Add deionized water to step 2 again, then add hydrogen peroxide with a concentration of 0.4wt%, start the ultrasonic generator (ultrasonic frequency is 22kHz, ultrasonic power is 225W), after 65 minutes of reaction at 45℃, remove the supernatant;

[0064] Step 4: Place the slurry after removing the supernatant in step 3 at 55℃ for 35 minutes for first sedimentation, then reduce the temperature to 33℃ again and stand for 35 minutes for second sedimentation, after sedimentation, extract the upper suspension by siphon;

[0065] Step 5: Place the upper suspension extracted in step 4 in a centrifuge, set the speed to 1750r / min and the temperature to 28℃ for the first centrifugation operation for 3 minutes, separate part of the impurities and larger particles; further increase the centrifugal speed to 2750r / min and reduce the temperature to 12℃, then perform the second centrifugation operation for 4 minutes, remove the precipitate after centrifugation, and retain the supernatant;

[0066] Step 6: Add sodium dithionite with a concentration of 0.11wt% to the supernatant obtained in step 5 and stir, after 35 minutes of reaction at 45℃, transfer the supernatant to a centrifuge for dewatering, the centrifugal speed during centrifugation is 4850r / min, and the centrifugation time is 18 minutes;

[0067] Step 7: Place the material after centrifugation in step 6 in a drying device with a drying temperature of 108℃, after complete drying, grind it to pass through a 325 mesh screen, and the uniform particle size and high purity bentonite product is obtained.

[0068] Example 6

[0069] A purification method for improving the purity of bentonite, the steps are as follows,

[0070] Step 1: Pretreat the bentonite, place the bentonite ore in a crushing device for crushing treatment until the particle size can pass through a 200 mesh screen, mix the sieved bentonite with deionized water at a mass ratio of 1:8 by fully stirring, and the stirring time is 32 minutes to form a uniform and stable slurry;

[0071] Step 2: Ultrasonic assisted chemical impurity removal is performed on the slurry obtained in step 1, after starting the ultrasonic generator (ultrasonic frequency is 23kHz, ultrasonic power is 230W), add hydrochloric acid with a concentration of 0.6wt% to the slurry, after 52 minutes of reaction at 32℃, carefully pour off the supernatant;

[0072] Step 3: Add deionized water to step 2 again, then add hydrogen peroxide with a concentration of 0.6wt%, start the ultrasonic generator (ultrasonic frequency is 23kHz, ultrasonic power is 230W), after 52 minutes of reaction at 32℃, remove the supernatant;

[0073] Step 4: Place the slurry after removing the supernatant in step 3 at 42℃ for 22 minutes for the first time. Settle, then reduce the temperature to 27℃ again and settle for 22 minutes for the second time. After settling, the upper suspension is extracted by siphon;

[0074] Step 5: Place the upper suspension extracted in step 4 in a centrifuge, set the speed to 1400r / min and the temperature to 23℃ for the first time. centrifugation for 4 minutes, separate part of the impurities and larger particles; further increase the centrifugal speed to 2400r / min, and then reduce the temperature to 13℃, and then perform the second time centrifugation for 5 minutes, remove the precipitate after centrifugation, and retain the supernatant;

[0075] Step 6: Add sodium hydrosulfite with a concentration of 0.1wt% to the supernatant obtained in step 5 and stir, after 22 minutes of reaction at 32℃, transfer the supernatant to a centrifuge for centrifugal dewatering, the centrifugal speed during centrifugation is 4700r / min, and the centrifugation time is 13 minutes;

[0076] Step 7: Place the material after centrifugation in step 6 in a drying device with a drying temperature of 106℃, after complete drying, grind it to pass through a 325 mesh screen, and the uniform particle size and high purity bentonite product is obtained.

[0077] Example 7

[0078] A purification method for improving the purity of bentonite, the steps are as follows,

[0079] Step 1: Pretreat the bentonite, place the bentonite ore in a crushing device for crushing treatment until the particle size can pass through a 200 mesh screen, mix the sieved bentonite with deionized water at a mass ratio of 1:9 by fully stirring, the stirring time is 33 minutes to form a uniform and stable slurry;

[0080] Step 2: Ultrasonic assisted chemical impurity removal is performed on the slurry obtained in step 1, after starting the ultrasonic generator (ultrasonic frequency is 28kHz, ultrasonic power is 280W), add hydrochloric acid with a concentration of 0.5wt% to the slurry, after 68 minutes of reaction at 48℃, carefully pour off the supernatant;

[0081] Step 3: Add deionized water to step 2 again, then add hydrogen peroxide with a concentration of 0.5wt%, start the ultrasonic generator (ultrasonic frequency is 28kHz, ultrasonic power is 280W), after 68 minutes of reaction at 48℃, remove the supernatant;

[0082] Step 4: Place the slurry after removing the supernatant in step 3 at 58℃ for 39 minutes for first sedimentation, then reduce the temperature to 28℃ again and stand for 38 minutes for second sedimentation, after sedimentation, extract the upper suspension by siphon;

[0083] Step 5: Place the upper suspension extracted in step 4 in a centrifuge, set the speed to 1850r / min and the temperature to 27℃ for the first centrifugation operation for 5 minutes, separate part of the impurities and larger particles; further increase the centrifugal speed to 2850r / min and reduce the temperature to 13℃, then perform the second centrifugation operation for 5 minutes again, remove the precipitate after centrifugation, and retain the supernatant;

[0084] Step 6: 0.11 wt% sodium hydrosulfite was added to the supernatant obtained in step 5 and stirred, and after 38 minutes of reaction at 48°C, the supernatant was transferred to a centrifuge for centrifugal dewatering, with a centrifugal speed of 4900 r / min and a centrifugal time of 17 minutes;

[0085] Step 7: The material after centrifugation in step 6 was placed in a drying device with a drying temperature of 102°C, and after complete drying, it was ground to pass through a 325 mesh screen, thereby obtaining a bentonite product with uniform particle size and high purity.

[0086] The above is only a preferred embodiment of the present application, and it should be noted that the above preferred embodiment should not be considered as limiting the present application, and the protection scope of the present application should be limited by the scope defined by the claims. For ordinary skilled persons in the art, several improvements and refinements can be made without departing from the spirit and scope of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for improving the purity of bentonite, characterized in that: The steps are as follows, Step 1: Pre-treat the bentonite by placing the bentonite ore in a crushing device and crushing it until the particle size can pass through a 200-mesh sieve. The sieved bentonite is thoroughly stirred and mixed with a certain proportion of deionized water to form a uniform and stable slurry. Step 2: The slurry obtained in step 1 is subjected to ultrasonic-assisted chemical impurity removal. After turning on the ultrasonic generator, a certain concentration of hydrochloric acid is added to the slurry. After reacting for a period of time at a certain temperature, the supernatant is carefully poured off. Step 3: Add deionized water to step 2 again, then add a certain concentration of hydrogen peroxide, start the ultrasonic generator, react at a certain temperature for a period of time, and then remove the supernatant; Step 4: The slurry after removing the supernatant in step 3 is allowed to stand for a period of time at a certain temperature for a first sedimentation, and then the temperature is lowered again and allowed to stand for a period of time for a second sedimentation. After the sedimentation is completed, the upper suspension is extracted by siphoning; Step 5: Place the upper suspension extracted in step 4 in a centrifuge, set the speed and temperature to perform a first centrifugation operation to separate some impurities and larger particles; further increase the centrifugal speed and perform a second centrifugation operation again to remove the sediment after centrifugation and retain the supernatant; Step 6: adding a certain concentration of sodium dithionite to the supernatant obtained in step 5 and stirring, and after reacting for a period of time, transferring the supernatant to a centrifuge for centrifugal dehydration; Step 7: Place the material after centrifugation in step 6 in a drying device, grind it after it is completely dried, and make it pass through a 325-mesh sieve to obtain a bentonite product with uniform particle size and high purity.

2. A method for improving the purity of bentonite according to claim 1, characterized in that: In step 1, the bentonite and deionized water are fully mixed in a mass ratio of 1:7-1:9, and the stirring time is 25-35 minutes.

3. A method for improving the purity of bentonite according to claim 1, characterized in that: In step 2, the concentration of the added hydrochloric acid is 0.4-0.6 wt %, the ultrasonic frequency is 20-30 kHz, the ultrasonic power is 250-350 W, the reaction time is 50-70 minutes, and the reaction temperature is 30-50° C.

4. A method for improving the purity of bentonite according to claim 1, characterized in that: In step 3, the concentration of the added hydrogen peroxide is 0.4-0.6 wt %, the ultrasonic frequency is 20-30 kHz, the ultrasonic power is 250-350 W, the reaction time is 50-70 minutes, and the reaction temperature is 30-50° C.

5. A method for improving the purity of bentonite according to claim 1, characterized in that: In step 4, the temperature during the first sedimentation is 40-60° C., the time for the first sedimentation is 20-40 minutes, the temperature during the second sedimentation is 25-35° C., and the time for the second sedimentation is 20-40 minutes.

6. A method for improving the purity of bentonite according to claim 1, characterized in that: In step 5, the centrifugal speed during the first separation is 1000-2000 r / min, the temperature is 20-30°C, and the centrifugal time is 1-5 minutes. The centrifugal speed during the second centrifugation is 2000-3000 r / min, the temperature is 5-15°C, and the centrifugal time is 4-6 minutes.

7. A method for improving the purity of bentonite according to claim 1, characterized in that: In step 6, the concentration of the sodium dithionite is 0.08-0.12 wt %, the reaction temperature is 30-50° C., the reaction time is 20-40 minutes, the centrifugal speed during the centrifugal operation is 4500-5500 r / min, and the centrifugal time is 10-20 minutes.

8. A method for improving the purity of bentonite according to claim 1, characterized in that: In step 7, the temperature in the drying equipment is set to 100-110°C.