A low-cost method for preparing nano / submicron barium sulfate powder

Abstract

This invention discloses a low-cost method for preparing nano / submicron barium sulfate powder, comprising the following steps: 1) Weighing and dissolving pulverized barium sulfide ore in hot water, filtering to obtain solution A; weighing sulfate and dissolving it in hot water, adding additives, and obtaining solution B after the additives dissolve; 2) Simultaneously pumping solutions A and B into a centrifugal device for reaction; adjusting the rotation speed, temperature, and feed flow rate of the centrifugal device, and obtaining a barium sulfate suspension after the reaction; 3) Allowing the barium sulfate suspension to stand for aging, washing, pressure filtration / centrifugation, or filtration to obtain a nano / submicron barium sulfate filter cake; 4) Drying, crushing, or separating the barium sulfate filter cake to obtain nano / submicron barium sulfate powder. This invention can prepare nano / submicron barium sulfate with an average particle size of 30-200 nm, narrow distribution, and high morphological regularity, with a morphology approaching cubic.

Description

Technical Field

[0001] This invention relates to the field of nano and submicron material preparation technology; specifically, it relates to a low-cost method for preparing nano / submicron barium sulfate powder. Background Technology

[0002] Barium sulfate, as a high-quality inorganic chemical raw material, possesses numerous superior characteristics such as low cost, easy availability, large storage capacity, strong weather resistance, high brightness, high whiteness, non-toxicity, strong chemical inertness, and resistance to acids and alkalis. Therefore, its applications are very wide-ranging, and it has been extensively used in composite materials, coatings, high-grade paints and inks, ceramics, papermaking, and many other fields. When classified according to particle size, barium sulfate with an average particle size D < 100 nm is classified as nano-barium sulfate; when the particle size range D is 100 nm < D < 1 μm, it is classified as submicron barium sulfate. Nano-barium sulfate and submicron barium sulfate have different focuses when applied to different scenarios. Nano-barium sulfate is mainly used in high-end coatings and inks (automotive original paint, electronic ink, etc.), fine plastic modification (battery separator coating, etc.), pharmaceuticals (contrast agents, cosmetics, etc.), and electronic materials (copper clad laminates, etc.); while submicron barium sulfate is mainly used in industrial coatings and powder coatings (matte paint, exterior wall paint, etc.), engineering plastic filler modification, papermaking, rubber elastomers, and mid-to-low-end contrast agents and cosmetics, etc.

[0003] Currently, domestic barium sulfate production mainly employs traditional processes such as the Glauber's salt-barite method, direct precipitation method, and microemulsion method. However, with industrial and technological development, the demand and standards for high-quality materials have further increased, leading to a significant rise in market quality standards for barium sulfate products. Although traditional processes have very mature production routes, their products lag significantly behind advanced foreign products in performance, specifically in terms of larger particle size (greater than 200nm), irregular morphology, and excessively wide particle size distribution. These defects limit domestically produced barium sulfate to general low-end industrial applications, severely restricting the full realization of its performance advantages. Between 2022 and 2024, the average annual export value of barium sulfate reached 1.3 billion yuan, while the average annual import value reached 100 million yuan, with precipitated barium sulfate accounting for over 60% of the total import value. Therefore, in the high-end barium sulfate market, China mainly relies on imports.

[0004] Nano-barium sulfate not only possesses the characteristics of traditional barium sulfate, such as strong chemical inertness, acid and alkali resistance, and non-toxicity, but also has unique properties such as small particle size, high surface energy, and large specific surface area. Therefore, nano-barium sulfate combines the inherent properties of ordinary barium sulfate with the unique advantages of nanomaterials, demonstrating significant potential for application in high-value-added fields. However, it is difficult to prepare nano-barium sulfate with uniform particle size distribution, regular shape, and small particle size using traditional processes: the Glauber's salt-barite method is difficult to obtain barium sulfate with small (less than 200 nm) and uniform particle size; and since the reaction of soluble barium salt with soluble sulfate to form barium sulfate is an extremely fast precipitation reaction, the core of preparing nano / submicron barium sulfate using precipitation methods is to achieve rapid and uniform mixing of the two solutions before the reaction.

[0005] In the preparation of nanoparticles using rapid reactions, the particle size distribution mainly depends on the nucleation process. Because the intrinsic rate of the chemical reaction is very fast or instantaneous, resulting in high supersaturation, the nucleation process is controlled by homogeneous nucleation. The nucleation rate is often expressed as... In the formula, k is a constant. Assuming supersaturation, m = 5-18. This demonstrates a strongly nonlinear process, where the nucleation rate is highly dependent on... ∆c The size and uniformity of its distribution at the spatial molecular scale, ∆c Even minute changes can cause significant variations in the nucleation rate, leading to uneven particle size distribution, poor batch-to-batch repeatability, and other problems. Therefore, controlling the nucleation process by managing the supersaturation level and its distribution within the apparatus is crucial for preparing nano / submicron barium sulfate with narrow particle size distribution using the precipitation method.

[0006] In theory, the greater the supersaturation, the more nuclei are formed, and the smaller the final particles. The magnitude of supersaturation mainly depends on the chemical reaction rate. For homogeneous reactions, the chemical reaction rate depends on the molecular mixing rate at the molecular scale; while for heterogeneous reactions, it depends on the interphase mass transfer rate. The uniformity of supersaturation distribution at the spatial molecular scale depends on the molecular mixing rate. Therefore, molecular mixing and interphase mass transfer are key factors affecting the nucleation process. Consequently, the preparation of high-quality nano / submicron barium sulfate places extremely high demands on preparation techniques and processes.

[0007] For example, Chinese patent application CN112299467A discloses "a method for preparing monodisperse oil-phase nano-barium sulfate dispersions". The nano-barium sulfate prepared by this method, after modification, achieves good dispersibility, uniform particle size distribution, and high stability in the oil phase. However, this method still has shortcomings: 1) The preparation method uses a high-cost barium source, and the obtained barium sulfate is approximately 15 nm in size, mainly concentrated in small particles; 2) This product is a liquid-phase dispersion, which is not suitable for situations requiring larger particle sizes (30-200 nm) and high uniformity of nano-barium sulfate powder.

[0008] For example, Chinese patent application CN105329930A discloses "a method for preparing nano-barium sulfate using a molecular mixing enhanced reactor." This method uses a hypergravity device and a sleeve-type microchannel reactor to prepare nano-barium sulfate powder with narrow distribution and small particle size. However, the drawbacks are that this preparation method uses a high-cost barium source, and the prepared barium sulfate particles are all less than 30 nm in size.

[0009] In summary, developing a batch-stable, simple, low-cost process for producing high-quality nano / submicron barium sulfate with a wider particle size range is crucial to meeting the domestic market's demand for high-end barium sulfate products. Summary of the Invention

[0010] The technical problem this application aims to solve is to provide a method for preparing nano / submicron barium sulfate powder. This method uses barium sulfide ore as raw material to prepare high-quality nano / submicron barium sulfate. It utilizes hypergravity technology to enhance molecular mixing and interphase mass transfer, enabling rapid and uniform mixing of barium sulfide and sulfate in a hypergravity device. This avoids localized high supersaturation and achieves uniform distribution of supersaturation at the molecular scale, resulting in nano / submicron barium sulfate with an average particle size of 30-200 nm, narrow particle size distribution, and highly regular morphology, with a morphology approaching cubic. This method is simple, low-cost, and produces nano / submicron barium sulfate with high batch stability, greatly improving the market competitiveness of high-end barium sulfate in China.

[0011] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for preparing nano / submicron barium sulfate powder includes the following steps: 1) Weigh out the crushed barium sulfide ore and dissolve it in hot water, then filter to obtain solution A; weigh out the sulfate and dissolve it in water, add the additive, and obtain solution B after the additive dissolves. 2) Simultaneously pump liquid A and liquid B into the centrifugal device for reaction; adjust the rotation speed, temperature and feed flow rate of the centrifugal device, and obtain barium sulfate suspension after reaction; 3) Allow the barium sulfate suspension to stand and mature, wash, press / centrifuge, or filter to obtain nano / submicron barium sulfate filter cake; 4) Barium sulfate filter cake is dried, crushed, or separated to obtain nano / submicron barium sulfate powder.

[0012] Preferably, in step 1), the barium sulfide ore source can be one or more of the barium sulfide ores produced in Guizhou, Hunan, Guangxi, Shaanxi, Hubei, Gansu and other places.

[0013] Preferably, in step 1), the sulfate is one or more of sodium sulfate, potassium sulfate, sodium sulfate, ammonium sulfate and their hydrates.

[0014] Preferably, in step 1), the additive is one or more of the following: titanate coupling agent, silane coupling agent, polyethylene glycol, nitrotriacetic acid (NTA), aminotrimethylenephosphonic acid, NTMP, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), sodium polyacrylate (PAAS), and sodium phosphate.

[0015] Preferably, in step 1), the concentration of solution A is 0.1-2.89 mol / L; the concentration of solution B is 0.1-3.43 mol / L; more preferably, the concentration of solution A is 0.5-2.5 mol / L, and the concentration of solution B is 0.5-3 mol / L.

[0016] Preferably, in step 1), the amount of additive added to liquid B is 0-20 wt%; more preferably, the amount of additive added to liquid B is 0-10 wt%.

[0017] Preferably, in step 2), the supergravity device refers to a device that achieves full mixing of materials through rotor rotation, including but not limited to a rotating packed bed and a stator-rotor reactor.

[0018] Preferably, in step 2), during the reaction process, the feed flow rate of liquid A is 100-2500 mol / L, the feed flow rate of liquid B is 100-2500 mol / L, and the feed flow rate ratio of liquid A to liquid B is 0.5:1-5:1; more preferably, the feed flow rate of liquid A is 500-2000 mol / L, the feed flow rate of liquid B is 500-2000 mol / L, and the feed flow rate ratio of liquid A to liquid B is 1:1-4:1.

[0019] Preferably, in step 2), the reaction temperature range is 50-90 ℃ and the rotor speed of the hypergravity device is 200-3000 rpm during the reaction process; more preferably, the reaction temperature range is 60-80 ℃ and the rotor speed of the hypergravity device is 1000-2500 rpm.

[0020] Preferably, in step 3), the settling and maturation time is 1-24 h, and the number of times the pressure filtration, washing, centrifugation and filtration operations are performed is 2-12; more preferably, the settling and maturation time is 1-12 h, and the number of times the pressure filtration, washing, centrifugation and filtration operations are performed is 5-8.

[0021] Preferably, in step 4), the drying method can be one or more of spray drying, drum drying, chain oven drying, forced-air oven drying, and hot air drying, with a drying temperature of 85-95℃ and a time of 12-48 h; the crushing time is 5-20 min, and the number of separations is 1-4 times; more preferably, the drying time is 24-48 h, the crushing time is 8-15 min, and the number of separations is 2-3 times.

[0022] Any range described in this invention includes the endpoint, any value between the endpoints, and any subrange consisting of the endpoint or any value between the endpoints.

[0023] Unless otherwise specified, all raw materials used in this invention can be obtained commercially, and the equipment used in this invention can be conventional equipment in the relevant field or refer to existing technology in the relevant field.

[0024] Compared with the prior art, the present invention has the following beneficial effects: 1) This invention can effectively enhance molecular mixing and interphase mass transfer through supergravity technology, enabling barium sulfide and sulfate to mix rapidly and uniformly, overcoming the problem that supersaturation is difficult to distribute evenly at the molecular scale.

[0025] 2) The nano / submicron barium sulfate prepared by this invention using barium sulfide ore as raw material has an average particle size of 30-200 nm, a narrow particle size distribution, and high morphological regularity.

[0026] 3) By using a supergravity device, the preparation of nano / submicron barium sulfate from barium sulfide can be carried out continuously, which greatly improves product quality and meets the needs of industrial continuous production. Attached Figure Description

[0027] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Figure 1 This is a process technology route diagram of the present invention; Figure 2 This is a transmission electron microscope image of the nano-barium sulfate prepared in Example 1 of the present invention; Figure 3 This is a particle size distribution diagram of the nano-barium sulfate prepared in Example 1 of the present invention; Figure 4Transmission electron microscopy image of the barium sulfate nanoparticles prepared in Example 2 of this invention. Figure 5 This is a transmission electron microscope image of the nano-barium sulfate prepared in Example 3 of the present invention; Figure 6 This is a transmission electron microscope image of the nano-barium sulfate prepared in Example 4 of the present invention; Figure 7 This is a transmission electron microscope image of the barium sulfate nanoparticles prepared in Example 25 of the present invention; Figure 8 This is a transmission electron microscope image of the nano-barium sulfate prepared in Example 26 of the present invention; Figure 9 This is a transmission electron microscope image of the barium sulfate nanoparticles prepared in Example 27 of the present invention; Figure 10 Transmission electron microscopy (TEM) images of the nano-barium sulfate prepared in Example 28 of this invention (from left to right: ore #1, #2, and #3). Figure 11 The image shows the XRD pattern of the nano-barium sulfate prepared in Example 28 of this invention. Figure 12 This is a transmission electron microscope image of submicron barium sulfate prepared in Example 19 of the present invention; Figure 13 This is a transmission electron microscope image of barium sulfate prepared in Comparative Example 1 of the present invention. Figure 14 This is a transmission electron microscope (TEM) image of the nano-barium sulfate prepared in Comparative Example 7 of this invention. Detailed Implementation

[0028] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0029] See Figure 1 As shown, as one aspect of the present invention, a method for preparing nano / submicron barium sulfate powder includes the following steps: 1) Weigh out the crushed barium sulfide ore and dissolve it in hot water, then filter to obtain solution A; weigh out the sulfate and dissolve it in water, add the additive, and obtain solution B after the additive dissolves. 2) Simultaneously pump liquid A and liquid B into the centrifugal device for reaction; adjust the rotation speed, temperature and feed flow rate of the centrifugal device, and obtain barium sulfate suspension after reaction; 3) Allow the barium sulfate suspension to stand and mature, wash, press / centrifuge, or filter to obtain nano / submicron barium sulfate filter cake; 4) Barium sulfate filter cake is dried, crushed, or separated to obtain nano / submicron barium sulfate powder.

[0030] According to certain embodiments of the present invention, in step 1), the barium sulfide ore source may be one or more of the barium sulfide ores produced in Guizhou, Hunan, Guangxi, Shaanxi, Hubei, Gansu and other places.

[0031] According to certain embodiments of the present invention, in step 1), the sulfate is one or more of sodium sulfate, potassium sulfate, sodium sulfate, ammonium sulfate and their hydrates.

[0032] According to certain embodiments of the present invention, in step 1), the additive is one or more of titanate coupling agent, silane coupling agent, polyethylene glycol, nitrotriacetic acid (NTA), aminotrimethylenephosphonic acid, NTMP, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), sodium polyacrylate (PAAS), and sodium phosphate.

[0033] According to some embodiments of the present invention, in step 1), the concentration of solution A is 0.1-2.89 mol / L; the concentration of solution B is 0.1-3.43 mol / L; more preferably, the concentration of solution A is 0.5-2.5 mol / L and the concentration of solution B is 0.5-3 mol / L.

[0034] According to certain embodiments of the present invention, in step 1), the amount of additive added to liquid B is 0-20 wt%, or 1-20 wt%, or 3-20 wt%, or 5-20 wt%, or 7-20 wt%, or 9-20 wt%; more preferably, the amount of additive added to liquid B is 0-10 wt%, or 1-10 wt%, or 3-10 wt%, or 5-10 wt%, or 7-10 wt%.

[0035] Preferably, in step 2), the supergravity device refers to a device that achieves full mixing of materials through rotor rotation, including but not limited to a rotating packed bed and a stator-rotor reactor.

[0036] According to certain embodiments of the present invention, in step 2), during the reaction process, the feed flow rate of liquid A is 100-2500 mol / L, the feed flow rate of liquid B is 100-2500 mol / L, and the feed flow rate ratio of liquid A to liquid B is 0.5:1-5:1; more preferably, the feed flow rate of liquid A is 500-2000 mol / L, the feed flow rate of liquid B is 500-2000 mol / L, and the feed flow rate ratio of liquid A to liquid B is 1:1-4:1.

[0037] According to some embodiments of the present invention, in step 2), during the reaction process, the reaction temperature range is 50-90°C and the rotor speed of the hypergravity device is 200-3000 rpm; more preferably, the reaction temperature range is 60-80°C and the rotor speed of the hypergravity device is 1000-2500 rpm.

[0038] According to certain embodiments of the present invention, in step 3), the settling and ripening time is 1-24 h, or 3-24 h, or 5-24 h, or 7-24 h, or 9-24 h; the number of times the pressure filtration, washing, centrifugation and filtration operations are performed is 2-12 times; more preferably, the settling and ripening time is 5-12 h, and the number of times the pressure filtration, washing, centrifugation and filtration operations are performed is 5-8 times.

[0039] According to certain embodiments of the present invention, in step 4), the drying method may be one or more of spray drying, drum drying, chain oven drying, forced-air oven drying, and hot air drying, with a drying temperature of 85-95°C and a time of 12-48 h; the crushing time is 5-20 min, and the number of separations is 1-4 times; more preferably, the drying time is 24-48 h, the crushing time is 8-15 min, and the number of separations is 2-3 times. Example 1

[0040] A method for preparing nano / submicron barium sulfate powder includes the following steps: 1) Add barium sulfide ore No. 1 in batches slowly to water at 50°C while continuously stirring; after the ore has been completely added, continue stirring for 2-3 hours until the barium sulfide in the ore is completely dissolved in the water; filter while hot to prepare a yellow 1.0 mol / L barium sulfide solution, and keep it warm for later use; add sodium sulfate to water at 50°C, and then add EDTA additive (1 wt%) to prepare a 1.0 mol / L colorless transparent sodium sulfate solution, and keep it warm for later use; 2) First, set the reaction temperature of the hypergravity device to 50℃, adjust the speed of the hypergravity device to 1500 rpm, and set the feed flow rate to 1000 ml / min; turn on the hypergravity reaction device and wait for it to run stably, then inject the barium sulfide solution and sodium sulfate solution into the hypergravity device for rapid reaction; the product is collected by removing the beginning and end of the product to ensure the stability of the sample quality, and finally obtains a nano barium sulfate suspension. 3) Let the collected nano-barium sulfate suspension stand for 2-3 hours until it separates into layers. Then, pour off the upper light yellow clear liquid and add an equal amount of deionized water. Stir and wash. Then, perform centrifugation, washing and other operations, and repeat 3-4 times to obtain the final nano-barium sulfate. 4) Place the nano-barium sulfate obtained in step 3) into a 90°C forced-air oven and dry for 24 hours, then crush, grind and separate to finally obtain nano-barium sulfate powder.

[0041] Figure 2 This is a TEM image of the nano-barium sulfate prepared in Example 1; from Figure 2 It can be found that the barium sulfate nanoparticles have a small particle size, with an average particle size of 36 nm and a high degree of morphological regularity.

[0042] Figure 3 This is a particle size distribution diagram of the nano-barium sulfate prepared in Example 1. Figure 3 It can be observed that the particle size distribution of nano-barium sulfate is narrow.

[0043] In this invention, the No. 1 barium sulfide ore is derived from a type of barium sulfide ore from Hubei Province, with a barium sulfide content of 55%. Example 2

[0044] Example 1 was repeated, except that a silane coupling agent was added to the sodium sulfate solution as an additive. The remaining steps and conditions were the same as in Example 1.

[0045] Figure 4 This is a TEM image of the barium sulfate nanoparticles prepared in Example 2 of this invention. Figure 4 It can be observed that the barium sulfate nanoparticles prepared in Example 2 still have a small particle size and a high degree of morphological regularity.

[0046] Testing revealed that the prepared nano-barium sulfate had an average particle size of approximately 65 nm and a narrow particle size distribution. Example 3

[0047] Repeat Example 1, except that: the barium sulfide solution was replaced with 1.2 mol / L, the sodium sulfate solution was replaced with potassium sulfate of the same concentration, the centrifugal rotation speed was set to 2000 rpm, and the remaining steps and conditions were the same as in Example 1.

[0048] Figure 5 This is a TEM image of the barium sulfate nanoparticles prepared in Example 3 of this invention. Figure 5 It can be observed that the barium sulfate nanoparticles prepared in Example 3 still have a relatively small particle size (average particle size of about 50 nm). Although the morphology regularity of the barium sulfate nanoparticles is relatively high, it is lower than that of those in Example 1. Example 4

[0049] Example 1 was repeated, except that the reaction temperature of the barium sulfide solution and sodium sulfate solution was adjusted to 60°C, and the feed flow rate was set to 1000 ml / min. The remaining steps and conditions were the same as in Example 1.

[0050] Figure 6 This is a TEM image of the barium sulfate nanoparticles prepared in Example 4 of this invention. Figure 6 It can be observed that the nano-barium sulfate did not change significantly after standing for 0 h and 24 h, and its particle size was also small (average particle size of about 40 nm) and its morphology was regular. Example 5

[0051] Example 1 was repeated, except that the post-treatment time for the nano-barium sulfate was 24 hours, and the number of washes was 5-6 times. The remaining steps and conditions were the same as in Example 1. Testing showed that the nano-barium sulfate prepared in this example had similar performance to that of Example 1. Example 6

[0052] Repeat Example 1, except that the additive in the sodium sulfate solution of the reaction solution is replaced with EGTA, the sodium sulfate solution is replaced with potassium sulfate of the same concentration, the centrifugal rotation speed is set to 1000 rpm, and the remaining steps and conditions are the same as in Example 1.

[0053] Testing revealed that the average particle size of the barium sulfate nanoparticles prepared in Example 6 was approximately 70 nm, with a relatively narrow particle size distribution. Example 7

[0054] Example 5 was repeated, except that the additive in the sodium sulfate solution of the reaction solution was changed to DTPA, the sodium sulfate solution was replaced with potassium sulfate of the same concentration, the centrifugal rotation speed was set to 1300 rpm, and the remaining steps and conditions were the same as in Example 1.

[0055] Testing revealed that the submicron barium sulfate prepared in Example 7 had an average particle size of approximately 105 nm and a relatively narrow particle size distribution. Example 8

[0056] Example 5 was repeated, except that the additive in the sodium sulfate solution of the reaction solution was replaced with PAAS, the sodium sulfate solution was replaced with potassium sulfate of the same concentration, the centrifugal rotation speed was set to 1100 rpm, and the remaining steps and conditions were the same as in Example 1.

[0057] Testing revealed that the average particle size of the barium sulfate nanoparticles prepared in Example 8 was approximately 81 nm, with a narrow particle size distribution and high regularity. Example 9

[0058] Example 1 was repeated, except that the reaction temperature was adjusted to 60°C. o C, the remaining conditions are the same as in Example 1.

[0059] Testing revealed that the average particle size of the barium sulfate nanoparticles prepared in Example 9 was approximately 48 nm, with a narrow particle size distribution and high regularity. Example 10

[0060] Repeat Example 1, except that the hypergravity rotation speed is set to 2000 rpm, the reaction temperature is adjusted to 60°C, and the remaining steps and conditions are the same as in Example 1.

[0061] Testing revealed that the average particle size of the barium sulfate nanoparticles prepared in Example 10 was approximately 42 nm, with a narrow particle size distribution and high regularity. Example 11

[0062] Repeat Example 1, except that the hypergravity rotation speed is set to 2000 rpm, the reaction temperature is adjusted to 70°C, and the remaining steps and conditions are the same as in Example 1.

[0063] Testing revealed that the average particle size of the barium sulfate nanoparticles prepared in Example 11 was approximately 52 nm, with a narrow particle size distribution and high regularity. Example 12 Repeat Example 1, except that the hypergravity rotation speed is set to 1000 rpm and the feed flow rate is adjusted to 500 ml / min. The remaining steps and conditions are the same as in Example 1.

[0064] Testing revealed that the submicron barium sulfate prepared in Example 12 had an average particle size of approximately 103 nm, with a narrow particle size distribution and high regularity. Example 13

[0065] Repeat Example 1, except that the hypergravity rotation speed is set to 3000 rpm, the reaction temperature is adjusted to 80°C, and the remaining steps and conditions are the same as in Example 1.

[0066] Testing revealed that the average particle size of the barium sulfate nanoparticles prepared in Example 13 was approximately 78 nm, with a narrow particle size distribution and high regularity. Example 14

[0067] Repeat Example 1, except that the speed of the hypergravity rotation is set to 3000 rpm, the feed flow rate is adjusted to 500 ml / min, the reaction temperature is adjusted to 80℃, and the remaining steps and conditions are the same as in Example 1.

[0068] Testing revealed that the average particle size of the barium sulfate nanoparticles prepared in Example 14 was approximately 69 nm, with a narrow particle size distribution and high regularity. Example 15

[0069] Repeat Example 1, except that the hypergravity rotation speed is set to 1000 rpm, the reaction temperature is adjusted to 80℃, the feed flow rate is adjusted to 500 ml / min, and the remaining steps and conditions are the same as in Example 1.

[0070] The average particle size of the submicron barium sulfate prepared in Example 15 was found to be approximately 128 nm. Example 16

[0071] Repeat Example 1, except that: the speed of the supergravity rotation is set to 1000 rpm, the solution concentration is changed to 0.5 mol / L, the drying method is changed from oven drying to hot air drying, and the remaining steps and conditions are the same as in Example 1.

[0072] The average particle size of the submicron barium sulfate prepared in Example 16 was found to be approximately 145 nm. Example 17

[0073] Repeat Example 1, except that the speed of the supergravity is set to 1000 rpm, and the drying method is changed from blower oven drying to chain oven drying. The remaining steps and conditions are the same as in Example 1.

[0074] The average particle size of the barium sulfate nanoparticles prepared in Example 17 was found to be approximately 49 nm. Example 18

[0075] Repeat Example 1, except that the speed of the supergravity is set to 1000 rpm, the drying method is changed to drum drying, and the remaining steps and conditions are the same as in Example 1.

[0076] The average particle size of the barium sulfate nanoparticles prepared in Example 18 was found to be approximately 48 nm. Example 19

[0077] Repeat Example 1, except that: the hypergravity rotation speed is set to 1000 rpm, the concentration of the reaction solution is changed to 0.7 mol / L, the concentration of the additive is changed to 5 wt%, and the remaining steps and conditions are the same as in Example 1.

[0078] like Figure 12 As shown, the average particle size of the submicron barium sulfate prepared in this Example 19 was approximately 180 nm, according to the test results. Example 20

[0079] Example 1 was repeated, except that the centrifugal rotation speed was set to 1000 rpm, the reaction solution concentration was changed to 0.5 mol / L, the amount of EDTA added to the sodium sulfate solution was changed to 10 wt%, and the drying method was changed to spray drying. The remaining steps and conditions were the same as in Example 1.

[0080] The average particle size of the submicron barium sulfate prepared in Example 20 was found to be approximately 200 nm.

[0081] Examples 21-24 Example 20 was repeated, except that the additive EDTA added to the sodium sulfate solution in the reaction solution was replaced with diethylenetriaminepentaacetic acid (DTPA), sodium polyacrylate (PAAS), or sodium phosphate; the remaining steps and conditions were the same as in Example 20. The average particle size of the submicron barium sulfate prepared in Examples 21-24 was determined to be between 150 and 200 nm. Example 25

[0082] Repeat Example 1, except that: replace barium sulfide ore #1 in Example 1 with barium sulfide ore #2, and replace sodium sulfate with potassium sulfate. The remaining steps and conditions are the same as in Example 1.

[0083] Figure 7 This is a TEM image of the nano-barium sulfate prepared in Example 25 of this invention; from Figure 7 It can be found that replacing barium sulfide ore #1 with barium sulfide ore #2 does not significantly change the quality of the prepared nano-barium sulfate, which still has a small particle size and good morphology.

[0084] In this invention, the No. 2 barium sulfide ore is derived from a type of barium sulfide ore from Hubei Province, with a barium sulfide content of 59%. Example 26

[0085] Repeat Example 1, except that the No. 1 barium sulfide ore in Example 1 is replaced with No. 3 barium sulfide ore, and the remaining steps and conditions are the same as in Example 1.

[0086] Figure 8 This is a TEM image of the nano-barium sulfate prepared in Example 26 of this invention; from Figure 8 It can be observed that when barium sulfide ore No. 1 was replaced with barium sulfide ore No. 3, the particle size was still small, but the degree of agglomeration of the sample increased.

[0087] In this invention, the No. 3 barium sulfide ore is derived from a type of barium sulfide ore from Hubei Province, with a barium sulfide content of 58%. Example 27

[0088] Example 1 was repeated, except that the No. 1 barium sulfide ore in Example 1 was replaced with No. 2 barium sulfide ore, the concentration of barium sulfide and sodium sulfate was changed to 2.0 mol / L, and the temperature was changed to 80°C. The remaining steps and conditions were the same as in Example 1.

[0089] Figure 9This is a TEM image of the barium sulfate nanoparticles prepared in Example 27 of this invention. Figure 9 It can be found that the average particle size of the barium sulfate nanoparticles is 41 nm. Although the average particle size has increased compared with Example 1, it is still relatively small, and its morphology still tends to be cubic. Example 28

[0090] Example 1 was repeated, except that three kinds of nano-barium sulfate products were prepared using barium sulfide ore No. 1, barium sulfide ore No. 2 and barium sulfide ore No. 3; the remaining steps and conditions were the same as in Example 1.

[0091] Figure 10 This is a TEM image of the nano-barium sulfate prepared in Example 28 of the present invention. Figure 11 The image shows the XRD pattern of the nano-barium sulfate prepared in Example 28 of the invention.

[0092] from Figure 10 It can be concluded that the preparation of nano-barium sulfate using three types of barium sulfide ores as raw materials all exhibits the characteristics of small particle size and good morphology. Simultaneously, through... Figure 11 The XRD data showed that the peaks of the barium sulfate prepared from the three ores corresponded one-to-one with those in the standard barium sulfate spectrum, indicating that the nano / submicron barium sulfate prepared by the centrifugal method were all typical barium sulfate crystals—orthorhombic crystals. At the same time, when compared with the standard spectrum, it was found that no additional impurity peaks appeared in the XRD spectra of the three nano / submicron barium sulfates, which indicates that the nano / submicron barium sulfate prepared in this invention has high purity. Examples 29-32

[0093] Example 25 was repeated, except that the No. 1 barium sulfide ore in Comparative Example 1 was replaced with No. 3 barium sulfide ore, and additives such as ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), sodium polyacrylate (PAAS), and sodium phosphate were added. The remaining steps and conditions were the same as in Example 1. The prepared nano-barium sulfate samples had high particle size uniformity and an average particle size range of 40-100 nm. Examples 33-37

[0094] Examples 29-30 were repeated, except that sodium sulfate in Examples 5-10 was replaced with sodium sulfate, additives were added, and the concentrations of the reaction solution, additives, and drying method were changed. The remaining steps and conditions were the same as in Example 1. The prepared nano / submicron barium sulfate samples exhibited high particle size uniformity with an average particle size range of 60-200 nm. Examples 38-42

[0095] Examples 33-37 were repeated, except that in the post-processing, the centrifugation operation was changed to pressure filtration, while the remaining steps and conditions were the same as in Example 1.

[0096] The prepared nano / submicron barium sulfate samples exhibited high particle size uniformity with an average particle size range of 59-195 nm. The results showed no significant changes compared to the previous examples and comparative examples. Example 43

[0097] Repeat Example 1, except that the content of the additive in solution B is reduced to 0 wt%, and the remaining steps and conditions are the same as in Example 1.

[0098] The prepared barium sulfate nanoparticles exhibited high particle size uniformity with an average particle size range of 31 nm. Compared to Example 1, the particle size decreased, while the particle size distribution slightly increased, but the sample morphology remained highly regular. Example 44

[0099] Example 10 was repeated, except that the content of the additive in solution B was reduced to 0 wt%, and the remaining steps and conditions were the same as in Example 10.

[0100] The prepared barium sulfate nanoparticles exhibited high particle size uniformity with an average particle size range of 40 nm, and a narrow and highly regular particle size distribution. Compared to Example 10, the particle size decreased, while the particle size distribution slightly increased. Examples 45-46

[0101] Examples 25-26 were repeated, except that the content of the additive in solution B was reduced to 0 wt%, and the remaining steps and conditions were the same as in Example 10.

[0102] The prepared nano-barium sulfate samples have a narrow particle size distribution and high regularity. The results also indicate that changing the mineral source will not have a significant impact on the barium sulfate product.

[0103] Comparative Example 1 Example 1 was repeated, except that barium sulfate was prepared using liquid A and liquid B in a reaction vessel, and the remaining steps and conditions were the same as in Example 1.

[0104] like Figure 13 As shown, the prepared barium sulfate has poor morphology, with poor particle size and morphological regularity, and is significantly different from the product prepared by the centrifugal method. Comparative Examples 2-6

[0105] Repeat Comparative Example 1, except that EDTA, diethylenetriaminepentaacetic acid (DTPA), sodium polyacrylate (PAAS), or sodium phosphate additives are added to solution B. The remaining steps and conditions are the same as those in Comparative Example 1.

[0106] Test results show that the prepared barium sulfate has a wide particle size distribution and poor morphological regularity, and the difference is still very obvious compared with the centrifugal method. Comparative Example 7

[0107] A method for preparing nano / submicron barium sulfate powder includes the following steps: Add 4000 ml of a 0.4 mol / L barium sulfide aqueous solution to the barium salt solution storage tank; add 4000 ml of a 0.4 mol / L sodium sulfate aqueous solution to the sulfate solution storage tank; Turn on the hypergravity device and adjust the rotation speed to 1000 rpm and control the temperature of the reaction system to 25℃. Feed the barium salt solution and sulfate solution into the rotating bed at a feed rate of 1000 ml / min for reaction. After the barium salt solution and sulfate solution have been fed and the resulting suspension has flowed out of the hypergravity rotating device, turn off the hypergravity rotating device. The resulting suspension was centrifuged at 5000 rpm for 10 minutes. The solid was then washed with pure water and dried in a vacuum oven for 20 hours. The resulting solid was then ground to obtain the product, nano-barium sulfate. It should be noted that the above preparation method is based on the conditions of Example 1 of patent CN105329930A to prepare barium sulfate. The difference is that barium sulfide is used instead of barium chloride as the raw material, and the concentration is also changed. Since barium sulfide has poor solubility at 25°C, it can only react at a lower concentration. Therefore, using barium sulfide as raw material and preparing barium sulfate at 25°C will greatly reduce production efficiency.

[0108] Test results show that the barium sulfide raw material is different from the barium salt used in the patent. Compared with the results in this patent, the average particle size of the prepared barium sulfate is still only below 30 nm, which cannot reach the particle size range described in this patent.

[0109] Of course, the above scenarios are merely illustrative examples. The system and apparatus of the present invention can be applied to aldol condensation reactions of various aldehydes or ketones and product purification. The substitution of the reaction system based on the concept of the present invention, although not necessarily one of the aldol condensation reactions of aldehydes or ketones, still falls within the scope defined by this application.

[0110] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A low-cost method for preparing nano / submicron barium sulfate powder, characterized in that, Includes the following steps: 1) Weigh out the crushed barium sulfide ore, dissolve it in hot water, and filter to obtain solution A; weigh out the sulfate, dissolve it in hot water, add the additive, and obtain solution B after the additive dissolves. 2) Simultaneously pump liquid A and liquid B into the centrifugal device for reaction; adjust the rotation speed, temperature and feed flow rate of the centrifugal device, and obtain barium sulfate suspension after reaction; 3) Allow the barium sulfate suspension to stand and mature, wash, press / centrifuge, or filter to obtain nano / submicron barium sulfate filter cake; 4) Barium sulfate filter cake is dried, crushed, or separated to obtain nano / submicron barium sulfate powder.

2. The method for preparing nano / submicron barium sulfate powder according to claim 1, characterized in that: In step 1), the barium sulfide ore is sourced from one or more of the barium sulfide ores produced in Guizhou, Hunan, Guangxi, Shaanxi, Hubei, or Gansu.

3. The method for preparing nano / submicron barium sulfate powder according to claim 1, characterized in that: In step 1), the sulfate is one or more of sodium sulfate, potassium sulfate, sodium sulfate, ammonium sulfate and their hydrates.

4. The method for preparing nano / submicron barium sulfate powder according to claim 1, characterized in that: In step 1), the additive is one or more of the following: titanate coupling agent, silane coupling agent, polyethylene glycol, hypozinotriacetic acid, aminotrimethylenephosphonic acid, NTMP, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, sodium polyacrylate, and sodium phosphate.

5. The method for preparing nano / submicron barium sulfate powder according to claim 1, characterized in that: In step 1), the concentration of solution A is 0.1-2.89 mol / L; the concentration of solution B is 0.1-3.43 mol / L; more preferably, the concentration of solution A is 0.5-2.5 mol / L and the concentration of solution B is 0.5-3 mol / L.

6. The method for preparing nano / submicron barium sulfate powder according to claim 1, characterized in that: In step 1), the amount of additive added to solution B is 0-20 wt%; more preferably, the amount of additive added to solution B is 0-10 wt%.

7. The method for preparing nano / submicron barium sulfate powder according to claim 1, characterized in that: In step 2), the supergravity device refers to a device that achieves full mixing of materials through rotor rotation, including but not limited to rotating packed beds and stator-rotor reactors.

8. The method for preparing nano / submicron barium sulfate powder according to claim 1, characterized in that: In step 2), during the reaction process, the feed flow rate of liquid A is 100-2500 mol / L, the feed flow rate of liquid B is 100-2500 mol / L, and the feed flow rate ratio of liquid A to liquid B is 0.5:1-5:1; more preferably, the feed flow rate of liquid A is 500-2000 mol / L, the feed flow rate of liquid B is 500-2000 mol / L, and the feed flow rate ratio of liquid A to liquid B is 1:1-4:

1.

9. The method for preparing nano / submicron barium sulfate powder according to claim 1, characterized in that: In step 2), during the reaction process, the reaction temperature range is 50-90℃, and the rotor speed of the hypergravity device is 200-3000 rpm; more preferably, the reaction temperature range is 60-80℃, and the rotor speed of the hypergravity device is 1000-2500 rpm.

10. The method for preparing nano / submicron barium sulfate powder according to claim 1, characterized in that: In step 3), the settling and maturation time is 0-24 h, and the number of times the pressure filtration, washing, centrifugation and filtration operations are performed is 2-12; more preferably, the settling and maturation time is 1-12 h, and the number of times the pressure filtration, washing, centrifugation and filtration operations are performed is 5-8. Preferably, in step 4), the drying method can be one or more of spray drying, drum drying, chain oven drying, forced-air oven drying, and hot air drying, with a drying temperature of 85-95℃ and a time of 12-48 h; the crushing time is 5-20 min, and the number of separations is 1-4 times; more preferably, the drying time is 24-48 h, the crushing time is 8-15 min, and the number of separations is 2-3 times.

Images