A method for recycling waste acid gas to prepare pigments

Abstract

The present invention discloses a method for recycling waste acid gas to prepare pigment, belonging to the technology of waste recycling. This method uses the waste acid gas generated during the preparation process of the encapsulated pigment as raw material, and uses the contained Si and F elements as the activated silicon source and mineralizing agent components respectively to produce vanadium zirconium blue ceramic pigment. The production process will not cause problems of high material consumption or energy consumption, and the production cycle is short; the obtained product has good color system quality, small particle size and high uniformity.

Description

Technical Field

[0001] The present invention relates to the field of waste recycling and regeneration, and particularly to a method for recycling waste acid gas to prepare pigments. Background Art

[0002] Encapsulated pigments are a type of glaze pigment commonly used in the existing ceramic process. Acid pickling treatment is involved in the production process, and a large amount of waste acid gas is generated during the acid pickling treatment. The main component of this waste acid gas is SiF4. SiF4 is colorless and toxic, with an asphyxiating odor, and is prone to deliquescence. It generates silicic acid and hydrogen fluoride in humid air and forms thick smoke, which causes serious damage to the human eyes, skin, mucous membranes and respiratory system, and also poses a great harm to the environment.

[0003] Vanadium-zirconium blue pigment is an artificially synthesized coloring mineral with vanadium as the chromogenic element and ZrSiO4 zircon as the color carrier matrix. The hue is sky blue, which is mainly used in the colored glazes of building sanitary ceramics, and can also be used for underglaze decoration or body pigments. Since the vanadium-zirconium blue pigment is based on zircon, and zircon crystals have excellent properties such as strong chemical corrosion resistance and good thermal stability, this also endows the zircon-based pigment with excellent properties such as strong coloring power, stable color development, pure color, wide adaptability, good miscibility and rich hues. At present, the synthesis methods of vanadium-zirconium blue pigment include solid-phase synthesis method and sol-gel method. In the solid-phase synthesis method, zirconia, silica, vanadium pentoxide or ammonium metavanadate are generally used together with acid salts and fluorides as mineralizers, and the product is prepared through steps such as ball milling, calcination and water washing. This method has low requirements for equipment, simple process and easy control, but the raw materials are not mixed evenly enough, and the reaction activity of the raw materials is relatively low, resulting in a higher calcination temperature, longer holding time and high production cost; at the same time, the obtained pigment has coarse grains and serious agglomeration, and needs to be ground later, and the final product has poor coloring power and uneven hue. The sol-gel method generally uses sodium silicate, zirconium oxychloride, sodium hydroxide, vanadium pentoxide and acids or salts of strong acids and weak bases as the initial raw materials, synthesizes a vanadium-zirconium blue gel precursor with water as the solvent, and then uses chlorides and fluorides as mineralizers, and obtains the product after high-temperature firing and washing. The obtained pigment has a pure hue, low firing temperature, low energy consumption, the final product is loose and easy to crush, and the color development effect is good. However, the sol-gel method has a relatively complex process and high production cost, and it is difficult to be applied to industrial production. Therefore, there is still a need to develop a method for preparing vanadium-zirconium blue ceramic pigment with good color system quality, uniform particles, easy processing and low production cost in the prior art. Summary of the Invention

[0004] Based on the defects of the existing technology, the purpose of the present invention is to provide a method for recycling waste acid gas to prepare pigments. This method uses the waste acid gas generated during the preparation process of the encapsulated pigments as raw materials, and uses the Si and F elements contained therein as the activated silicon source and mineralizing agent components respectively to produce vanadium zirconium blue ceramic pigments. The production process will not cause problems of high material consumption or energy consumption, and the production cycle is short; the obtained product has good color system quality, small particle size and high uniformity.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for recycling waste acid gas to prepare pigments, comprising the following steps:

[0007] (1) Absorb the waste acid gas with an alkali solution, and after solid-liquid separation of the obtained mixture, obtain a filter cake;

[0008] (2) Disperse the filter cake in a solvent, and then subject the obtained mixed solution to sand grinding treatment to obtain an activated slurry;

[0009] (3) Disperse and mix zirconium oxychloride and urea in a solvent for a first-stage reaction, and then add a vanadium source and the activated slurry to the obtained mixed solution and continue the second-stage reaction until complete. Cool, wash, and dry to obtain a reaction material;

[0010] (4) Crush the reaction material and then calcine it, followed by secondary crushing and sequentially sieving, washing, and drying to obtain the pigment.

[0011] The method for preparing pigments of the present invention is carried out by the solution method. Compared with the solid-phase method, it can make the raw material mixing uniformity higher, the calcination temperature lower, the energy consumption lower, and the uniformity of the raw materials during the mixing process higher; compared with the sol-gel method, the process steps are simpler and more convenient and easier to operate. In the method for preparing the pigment, the waste acid gas (mainly composed of SiF4) generated in the same process field is fully utilized, and the Si and F elements contained therein are used as the silicon source and fluoride mineralizing agent respectively. Among them, the F element can be directly used as a mineralizing agent after reacting and mixing with the raw materials, without the addition of an additional mineralizing agent. At the same time, since composite salts such as sodium sulfate and ammonium chloride will be continuously generated during the whole process, these substances will also react as mineralizing agents, effectively improving the quality of the overall material and shortening the production cycle. The finally prepared pigment product not only has bright colors, deeper color development, strong coloring power, but also has smaller particle size and concentrated size distribution, and is more suitable for use after subsequent ball milling or direct use.

[0012] Preferably, in the step (1), the alkali solution is an aqueous sodium hydroxide solution with a mass concentration of 15-30%.

[0013] More preferably, in the step (1), the waste acid gas is introduced from the top into a spray absorption tower and absorbed by the alkali solution, and then the mixture is subjected to solid-liquid separation at the bottom of the spray absorption tower.

[0014] The waste acid gas is absorbed by a spray absorption tower, and the absorption efficiency of the waste acid gas can be higher and the conversion can be more complete by utilizing the gravity effect.

[0015] Preferably, in the step (2), the solvent is water, and the mixed solution further contains a dispersant.

[0016] More preferably, the dispersant is at least one of polyvinylpyrrolidone and sodium polyacrylate.

[0017] Preferably, in the step (2), the solid-liquid ratio of the filter cake to the solvent is 1 kg:(3 - 5) L.

[0018] More preferably, the particle size D50 of the activated slurry is 0.5 - 1 μm.

[0019] If the grinding degree of the activated slurry is not good during the preparation process, it may cause the overall particles of the finally obtained activated slurry to be too large or the particle size distribution to be uneven, which may affect its use as an activated silicon source and a mineralizing agent component in the subsequent process.

[0020] Preferably, in the step (3), the vanadium source is vanadium pentoxide, and the molar ratio of zirconium oxychloride, urea, vanadium pentoxide and the activated slurry is 1:(1.5 - 3):(0.04 - 0.15):(0.9 - 1.3), and the molar amount of the activated slurry is calculated based on the silicon element in the activated slurry.

[0021] It is found by the inventor's experiment that when the ratio of the above raw materials exceeds the above range, there may be excess reaction materials (such as zirconium dioxide, silicon dioxide, etc.) after the reaction of each component, and these materials may affect the color system effect of the finally prepared product, while the color system effect of the product prepared by mixing the raw materials within the above preferred ratio range is the best.

[0022] Preferably, in the step (3), the solvent is water, the mixed solution further contains a dispersant, and the dispersant is at least one of polyvinylpyrrolidone and sodium polyacrylate.

[0023] Preferably, in the step (3), the temperature during the first-stage mixing reaction is 80 - 100 °C, the mixing rate is 100 - 200 r / min, the time is 10 - 24 h; the time of the second-stage reaction is 2 - 5 h.

[0024] During the two-stage reaction process, in addition to the activated slurry, mineralizing agents are continuously generated in the reactants of other raw materials, continuously optimizing the configuration of the overall product, and at the same time, phenomena such as agglomeration and accumulation will not occur.

[0025] Preferably, in the step (4), the calcination temperature is 800 - 1000 °C, and the time is 0.5 - 1.5 h.

[0026] Preferably, the mesh number of the sieve during sieving in step (4) is 325-400 meshes.

[0027] Another object of the present invention is also to provide the vanadium zirconium blue ceramic pigment prepared by recycling the waste acid gas for the preparation of pigments.

[0028] The beneficial effects of the present invention are as follows: The present invention provides a method for recycling waste acid gas to prepare pigments. This method uses the waste acid gas generated during the preparation of the encapsulated pigment as a raw material, and uses the Si and F elements contained therein as the activated silicon source and mineralizing agent components respectively to produce vanadium zirconium blue ceramic pigments. The production process will not cause problems of high material consumption or energy consumption, and the production cycle is short; the obtained product has good color system quality, small particle size and high uniformity. The present invention also provides the vanadium zirconium blue ceramic pigment prepared by the above method, and this product has high production cost performance and good quality. Specific Embodiments

[0029] In order to better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments and comparative examples. The purpose is to understand the content of the present invention in detail, rather than a limitation to the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention. The experimental reagents, raw materials and instruments designed in the embodiments and comparative examples of the present invention are all common ordinary reagents, raw materials and instruments unless otherwise specified.

[0030] Example 1

[0031] An embodiment of the method for recycling waste acid gas to prepare pigments according to the present invention includes the following steps:

[0032] (1) Pass the waste acid gas mainly composed of SiF4 into a spray absorption tower through a vacuum pump, and absorb the waste acid gas from the top with a sodium hydroxide solution with a mass concentration of 15%. After the mixture obtained at the bottom of the spray absorption tower is subjected to solid-liquid separation, a filter cake is obtained;

[0033] (2) Disperse the filter cake in water according to a solid-liquid ratio of 1 kg: 3 L, add 0.02% of the mass of the filter cake of polyvinylpyrrolidone as a dispersant, and then put the obtained mixed liquid into a sand mill for sanding treatment until the particle size D50 of the particles in the slurry is 0.5 μm to obtain an activated slurry;

[0034] (3) Disperse zirconium oxychloride, urea, and polyvinylpyrrolidone evenly in water, transfer them to a reaction barrel, control the normal pressure at 80 °C, mix at a rotation speed of 100 r / min for a first-stage reaction for 24 h. Then add vanadium pentoxide and the activation slurry to the obtained mixed solution and continue the second-stage reaction for 5 h until complete. Cool, wash with water, and dry at 95 °C to obtain the reaction material. Based on the silicon element in the activation slurry, the molar ratio of zirconium oxychloride, urea, vanadium pentoxide, and the activation slurry is 1:3:0.04:0.9, and the addition amount of polyvinylpyrrolidone is 0.2% of the mass of zirconium oxychloride;

[0035] (4) After the reaction material is crushed, put it into a sagger, cover it, and calcine at 800 °C for 1 h. Then crush it twice and pass through a 325-mesh sieve in sequence, wash until the conductivity < 1 ms / cm, and spray-dry at 300 °C to obtain the vanadium zirconium blue ceramic pigment.

[0036] Example 2

[0037] An embodiment of the method for preparing a pigment by recycling waste acid gas according to the present invention includes the following steps:

[0038] (1) Pass the waste acid gas mainly composed of SiF4 into a spray absorption tower through a vacuum pump, and absorb the waste acid gas from the top with a 20% sodium hydroxide solution by mass concentration. After the mixture obtained at the bottom of the spray absorption tower is subjected to solid-liquid separation, a filter cake is obtained;

[0039] (2) Disperse the filter cake in water according to a solid-liquid ratio of 1 kg:4 L, add 0.06% of the mass of the filter cake of polyvinylpyrrolidone as a dispersant, and then put the obtained mixed solution into a sand mill for sanding treatment until the particle size D50 of the particles in the slurry is 0.8 μm to obtain the activation slurry;

[0040] (3) Disperse zirconium oxychloride, urea, and polyvinylpyrrolidone evenly in water, transfer them to a reaction barrel, control the normal pressure at 90 °C, mix at a rotation speed of 150 r / min for a first-stage reaction for 20 h. Then add vanadium pentoxide and the activation slurry to the obtained mixed solution and continue the second-stage reaction for 3 h until complete. Cool, wash with water, and dry at 100 °C to obtain the reaction material. Based on the silicon element in the activation slurry, the molar ratio of zirconium oxychloride, urea, vanadium pentoxide, and the activation slurry is 1:2.5:0.08:1, and the addition amount of polyvinylpyrrolidone is 0.12% of the mass of zirconium oxychloride;

[0041] (4) After the reaction material is crushed, put it into a sagger, cover it, and calcine at 900 °C for 1 h. Then crush it twice and pass through a 400-mesh sieve in sequence, wash until the conductivity < 1 ms / cm, and spray-dry at 300 °C to obtain the vanadium zirconium blue ceramic pigment.

[0042] Example 3

[0043] An embodiment of the method for preparing a pigment by recycling waste acid gas according to the present invention includes the following steps:

[0044] (1) The waste acid gas mainly composed of SiF4 is introduced into a spray absorption tower through a vacuum pump, and the waste acid gas is absorbed from the top with a sodium hydroxide solution with a mass concentration of 30%. After the mixture obtained at the bottom of the spray absorption tower is subjected to solid-liquid separation, a filter cake is obtained.

[0045] (2) The filter cake is dispersed in water according to a solid-liquid ratio of 1 kg: 5 L, and 0.2% of sodium polyacrylate based on the mass of the filter cake is added as a dispersant. Subsequently, the obtained mixed solution is put into a sand mill for sanding treatment until the particle size D50 of the particles in the slurry is 1 μm, and an activated slurry is obtained.

[0046] (3) Zirconium oxychloride, urea and sodium polyacrylate are dispersed evenly in water, transferred to a reaction barrel and controlled at 95 °C under normal pressure, and mixed at a rotation speed of 200 r / min for a first-stage reaction for 15 h. The obtained mixed solution is then added with vanadium pentoxide and the activated slurry to continue the second-stage reaction for 2 h until complete. After cooling, washing with water and drying at 110 °C, a reaction material is obtained; based on the silicon element in the activated slurry, the molar ratio of zirconium oxychloride, urea, vanadium pentoxide and the activated slurry is 1: 2: 0.1: 1.2, and the addition amount of sodium polyacrylate is 0.1% of the mass of zirconium oxychloride.

[0047] (4) The reaction material is pulverized and then put into a crucible, covered and calcined at 1000 °C for 1 h. Subsequently, it is pulverized for the second time and successively passed through a 325-mesh sieve, washed until the conductivity < 1 ms / cm, and spray-dried at 250 °C to obtain the vanadium zirconium blue ceramic pigment.

[0048] Example 4

[0049] An embodiment of the method for recycling waste acid gas to prepare pigments according to the present invention includes the following steps:

[0050] (1) The waste acid gas mainly composed of SiF4 is introduced into a spray absorption tower through a vacuum pump, and the waste acid gas is absorbed from the top with a sodium hydroxide solution with a mass concentration of 25%. After the mixture obtained at the bottom of the spray absorption tower is subjected to solid-liquid separation, a filter cake is obtained.

[0051] (2) The filter cake is dispersed in water according to a solid-liquid ratio of 1 kg: 4 L, and 0.1% of sodium polyacrylate based on the mass of the filter cake is added as a dispersant. Subsequently, the obtained mixed solution is put into a sand mill for sanding treatment until the particle size D50 of the particles in the slurry is 0.7 μm, and an activated slurry is obtained.

[0052] (3) Disperse zirconium oxychloride, urea, and sodium polyacrylate evenly in water, transfer it to a reaction barrel, and control the normal pressure at 100 °C. Mix at a rotation speed of 150 r / min for a first-stage reaction for 10 h. Then add vanadium pentoxide and the activation slurry to the obtained mixed solution and continue the second-stage reaction for 4 h until complete. Cool, wash with water, and dry at 100 °C to obtain the reaction material; based on the silicon element in the activation slurry, the molar ratio of zirconium oxychloride, urea, vanadium pentoxide, and the activation slurry is 1:1.5:0.15:1.3, and the addition amount of polyvinylpyrrolidone is 0.2% of the mass of zirconium oxychloride;

[0053] (4) After the reaction material is crushed, put it into a sagger, cover it, and calcine at 950 °C for 1 h. Then crush it twice, pass through a 400-mesh sieve in sequence, wash until the conductivity < 1 ms / cm, and spray dry at 300 °C to obtain the vanadium zirconium blue ceramic pigment.

[0054] Example 5

[0055] An example of the method for preparing pigments by recycling waste acid gas according to the present invention, the difference from Example 1 is only that the step (2) is as follows:

[0056] (2) Disperse the filter cake in water according to a solid-liquid ratio of 1 kg: 3 L, add 0.02% of the mass of the filter cake of polyvinylpyrrolidone as a dispersant, and then put the obtained mixed solution into a sand mill for sanding treatment until the particle size D50 of the particles in the slurry = 1.5 μm to obtain the activation slurry.

[0057] Example 6

[0058] An example of the method for preparing pigments by recycling waste acid gas according to the present invention, the difference from Example 1 is only that the step (2) is as follows:

[0059] (2) Disperse the filter cake in water according to a solid-liquid ratio of 1 kg: 3 L, add 0.02% of the mass of the filter cake of polyvinylpyrrolidone as a dispersant, and then put the obtained mixed solution into a sand mill for sanding treatment until the particle size D50 of the particles in the slurry = 2 μm to obtain the activation slurry.

[0060] Example 7

[0061] An example of the method for preparing pigments by recycling waste acid gas according to the present invention, the difference from Example 1 is only that in step (3), based on the silicon element in the activation slurry, the molar ratio of zirconium oxychloride, urea, vanadium pentoxide, and the activation slurry is 1:3:0.04:0.6.

[0062] Example 8

[0063] An embodiment of the method for recycling waste acid gas to prepare pigment according to the present invention is only different from Embodiment 1 in that in step (3), based on the silicon element in the activated slurry, the molar ratio of zirconium oxychloride, urea, vanadium pentoxide and the activated slurry is 1:3:0.04:1.5.

[0064] Comparative Example 1

[0065] A method for preparing vanadium-zirconium blue pigment, comprising the following steps:

[0066] Weigh various raw materials accurately according to the formula mass ratio (52.5 parts of zirconia, 26 parts of quartz powder, 5 parts of vanadium pentoxide, 4 parts of sodium fluoride, 3.5 parts of sodium chloride, 9 parts of potassium sulfate), mix them evenly by dry method, put them into a sagger, cover it, and calcine at 950 °C for 2 h, then crush, pass through a 325-mesh sieve, wash, and dry to obtain vanadium-zirconium blue ceramic pigment.

[0067] Comparative Example 2

[0068] A method for preparing vanadium-zirconium blue pigment is only different from Embodiment 1 and comprises the following steps:

[0069] (1) Disperse zirconium oxychloride, urea and polyvinylpyrrolidone evenly in water, transfer them to a reaction barrel, control the normal pressure at 90 °C, mix at a rotation speed of 150 r / min for a first-stage reaction for 20 h, then add vanadium pentoxide and silica sol to the obtained mixture and continue the second-stage reaction for 3 h until complete, cool, wash with water, and dry at 100 °C to obtain a reaction material; the molar ratio of zirconium oxychloride, urea, vanadium pentoxide and silica sol is 1:2.5:0.08:1, and the addition amount of polyvinylpyrrolidone is 0.12% of the mass of zirconium oxychloride; the silica sol is selected from the product of model ZS-30 produced by Zhejiang Yuda Chemical Co., Ltd.;

[0070] (2) Add 5% sodium fluoride and 10% sodium sulfate to the reaction material, crush it, put it into a sagger, cover it, and calcine at 900 °C for 1 h, then crush it twice and pass through a 400-mesh sieve in turn, wash until the conductivity < 1 ms / cm, and spray-dry at 300 °C to obtain vanadium-zirconium blue ceramic pigment.

[0071] Comparative Example 3

[0072] A method for preparing vanadium-zirconium blue pigment is only different from Embodiment 1 and comprises the following steps:

[0073] (1) Pass the waste acid gas mainly composed of SiF4 into a spray absorption tower through a vacuum pump, and absorb the waste acid gas from the top with a sodium hydroxide solution with a mass concentration of 20%. After solid-liquid separation of the mixture obtained at the bottom of the spray absorption tower, a filter cake is obtained;

[0074] (2) Disperse the filter cake in water according to the solid-liquid ratio of 1 kg:3 L and stir evenly to obtain an activated slurry;

[0075] (3) Disperse zirconium oxychloride, urea, and polyvinylpyrrolidone evenly in water, transfer it to a reaction barrel, control the normal pressure at 90 °C, mix at a rotation speed of 150 r / min for a first-stage reaction for 20 h. Then add vanadium pentoxide and activation slurry to the obtained mixed solution and continue the second-stage reaction for 3 h until complete. Cool, wash with water, and dry at 100 °C to obtain a reaction material; based on the silicon element in the activation slurry, the molar ratio of zirconium oxychloride, urea, vanadium pentoxide, and activation slurry is 1:2.5:0.08:1, and the addition amount of polyvinylpyrrolidone is 0.12% of the mass of zirconium oxychloride;

[0076] (4) After the reaction material is pulverized, put it into a sagger, cover it, and calcine at 900 °C for 1 h. Then pulverize it for the second time, pass through a 400-mesh sieve in sequence, wash until the conductivity < 1 ms / cm, and spray dry at 300 °C to obtain the vanadium zirconium blue ceramic pigment.

[0077] Effect Example 1

[0078] To verify the quality of the pigment prepared by the method for recycling waste acid gas to prepare pigment described in the present invention, take 0.6 g of the pigment obtained in each example and comparative example respectively, add it to 20 g of the same commercially available transparent glaze, add an appropriate amount of water, ball mill for 2 min, then scrape the glaze onto the brick board with a glazing tool, and calcine at 1180 °C respectively. Measure the chromaticity with a CM-2300d type spectrophotometer, and record the measured Lab values respectively. The results are shown in Table 1.

[0079] Table 1

[0080] Project L* a* b* Example 1 68.55 -16.60 -19.02 Example 2 68.61 -16.68 -19.12 Example 3 68.55 -16.49 -19.46 Example 4 68.44 -16.54 -19.31 Example 5 69.14 -16.11 -18.63 Example 6 69.35 -15.96 -18.11 Example 7 71.05 -15.36 -17.01 Example 8 70.62 -15.57 -17.28 Comparative Example 1 69.31 -16.00 -18.48 Comparative Example 2 69.25 -16.08 -18.56 Comparative Example 3 70.21 -15.72 -17.67

[0081] It can be seen from Table 1 that the vanadium zirconium blue ceramic pigments obtained in Examples 1 to 4 prepared by the method described in the present invention have higher color vividness compared to the products prepared by the traditional solid-phase method; according to the performance of the products in Example 1, Examples 5 to 6, and Comparative Example 3, it can be seen that during the preparation process of the activation slurry, the grinding effect and the particle size of the particles after grinding will directly affect the color system effect of the product. However, simply using conventional stirring to prepare the activation slurry, the product of Comparative Example 3 finally prepared obviously cannot achieve the ideal color system effect; according to the test results of the products in Examples 7 to 8, during the raw material mixing process, increasing or decreasing the addition amount of the activation slurry will change the components in the final product, which may lead to a reduction in the color system effect of the product.

[0082] Effect Example 2

[0083] Perform particle size distribution tests on the products obtained in each example and comparative example using a Malvern MS3000 particle size analyzer. The results are shown in Table 2.

[0084] Table 2

[0085] Project D50 (μm) D90 (μm) D97 (μm) D100 (μm) Example 1 2.08 4.45 6.81 9.85 Example 2 1.87 4.01 6.32 9.56 Example 3 1.74 3.62 5.88 8.60 Example 4 1.72 3.86 6.09 8.85 Example 5 2.61 4.86 7.30 10.26 Example 6 2.86 5.01 7.57 10.53 Example 7 1.85 4.28 6.56 9.51 Example 8 1.97 4.34 6.72 9.63 Comparative Example 1 3.36 6.56 8.19 11.53 Comparative Example 2 3.14 6.44 8.01 11.11 Comparative Example 3 3.21 6.21 7.93 11.02

[0086] As can be seen from Table 2, the vanadium zirconium blue ceramic pigment prepared by the method of the present invention has the characteristics of small particle size and narrow particle size distribution. The D50 of each product can reach below 3 μm and the D100 can reach below 11 μm, which makes the coloring effect better during subsequent further processing or direct use. For the product of Comparative Example 1 prepared by the traditional solid-phase method, the D50 reached 3.36 μm and the D100 reached 11.53 μm, obviously it is difficult to reach the ideal size. For the product of Comparative Example 2, the activation slurry described in the present invention was not used during the preparation process, but conventional activation silicon source and mineralizer were used instead. Although the color development effect of the prepared product is similar to that of the products of Examples 1 to 4, it cannot achieve the effect of small particle size and narrow distribution. For the product of Comparative Example 3, although the activation slurry was used during the preparation process, the particles in the slurry were not ground, and the expected activity effect could not be achieved when mixed with other raw materials. Not only is the color development effect insufficient, but also the size requirements cannot be met.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for recycling waste acid gas to prepare pigments, characterized in that, It includes the following steps: (1) Absorb the waste acid gas with an alkali solution. After the obtained mixture is subjected to solid-liquid separation, a filter cake is obtained. The waste acid gas is the gas generated during the pickling process in the preparation of the encapsulated pigment, including the component SiF4. The waste acid gas is introduced from the top into a spray absorption tower and absorbed by the alkali solution, and then the mixture is subjected to solid-liquid separation at the bottom of the spray absorption tower. The alkali solution is an aqueous sodium hydroxide solution with a mass concentration of 15-30%; (2) Disperse the filter cake in a solvent, and then subject the obtained mixed liquid to sand grinding treatment to obtain an activated slurry. The solid-liquid ratio of the filter cake to the solvent is 1 kg:(3-5) L. The particle size D50 of the activated slurry is 0.5-1 μm; (3) Disperse and mix zirconium oxychloride and urea in a solvent for a first-stage reaction. Then, add a vanadium source and the activated slurry to the obtained mixed liquid and continue the second-stage reaction until completion. Cool, wash, and dry to obtain a reaction material. The vanadium source is vanadium pentoxide. The molar ratio of zirconium oxychloride, urea, vanadium pentoxide, and the activated slurry is 1:(1.5-3):(0.04-0.15):(0.9-1.3), and the moles of the activated slurry are calculated based on the silicon element in the activated slurry; (4) The reaction material is crushed and then calcined, followed by secondary crushing and successively sieving, washing, and drying to obtain the pigment.

2. The method for preparing pigments by recycling waste acid gas as claimed in claim 1, wherein In step (2), the solvent is water, and the mixed liquid also contains a dispersant.

3. The method for preparing a pigment by recycling waste acid gas as claimed in claim 2, wherein, The dispersant is at least one of polyvinylpyrrolidone and sodium polyacrylate.

4. The method for preparing a colorant by recycling waste acid gas as claimed in claim 1, wherein In step (3), the solvent is water, the mixed liquid also contains a dispersant, and the dispersant is at least one of polyvinylpyrrolidone and sodium polyacrylate.

5. The method for preparing pigments by recycling waste acid gas as claimed in claim 1, wherein In step (3), the temperature during the first-stage mixing reaction is 80-100 °C, the mixing rate is 100-200 r / min, and the time is 10-24 h. The time for the second-stage reaction is 2-5 h.

6. The method for preparing a colorant by recycling waste acid gas as claimed in claim 1, wherein In step (4), the calcination temperature is 800-1000 °C, and the time is 0.5-1.5 h. The mesh number of the sieve during sieving is 325-400 mesh.