Use of red mud as raw material for preparing porcelain clay

Abstract

The present invention relates to the technical field of solid waste utilization, and in particular relates to the use of red mud as a raw material for preparing porcelain clay. Particularly, a preparation method for porcelain clay comprises the following steps: A) mixing red mud and an acid solution, and carrying out a reaction to obtain a salt solution having a pH value of 4-6.8; B) carrying out filter pressing on the solution obtained in step A) so as to control the mass content of water to be not higher than 50%, then introducing compressed air, and carrying out drying with the compressed air; C) mixing water and the solid obtained after the drying with compressed air, and carrying out filter pressing again; D) drying and burning the solid obtained after the filter pressing in step C); and E) carrying out iron removal on the burned material obtained in step D) to obtain porcelain clay. By researching, the present applicant found that processing red mud via such steps described above can utilize the vast majority of components in red mud and thus produce high-quality porcelain clay with very little waste residues and waste water generated thereby.

Description

Application of red mud as raw material for preparation of porcelain clay

[0001] The present application claims priority to the Chinese patent application No. 202410706666.2 filed on June 03, 2024, and titled "Application of red mud as raw material for preparation of porcelain clay", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of solid waste utilization, and particularly relates to application of red mud as raw material for preparation of porcelain clay. BACKGROUND

[0003] The production of alumina generates a large amount of waste residue, with more than 100 million tons per year nationwide. The waste residue has a high iron content and is red in color, hence the name red mud. The main components in red mud include alumina, silicon oxide, iron oxide, titanium oxide, calcium oxide, sodium oxide, potassium oxide, etc. It is urgent to utilize red mud and turn waste into treasure. There are generally two methods for utilizing red mud, one is to extract valuable substances such as titanium dioxide or certain rare metals, which can achieve economic benefits. However, there is still a lot of waste material, and it is difficult to implement in practice. The second method is to utilize most of the substances in red mud, resulting in little waste residue and waste water. This is a more ideal way. However, how to utilize red mud is still a subject of study in the field. SUMMARY

[0004] Therefore, the present application aims to solve the technical problem of providing application of red mud as raw material for preparation of porcelain clay. The present application can utilize most of the substances in red mud to produce porcelain clay with good performance, and little waste residue and waste water is generated.

[0005] The present application provides application of red mud as raw material for preparation of porcelain clay.

[0006] The present application also provides a preparation method of porcelain clay, comprising the following steps:

[0007] A) mixing red mud and an acid solution to react, to obtain a salt solution with a pH value of 4-6.8;

[0008] B) performing pressure filtration on the solution obtained in step A) to control the mass content of water to be not higher than 50%, and then performing air pressure drying by introducing compressed air;

[0009] C) mixing the solid after air pressure drying with water and performing pressure filtration again;

[0010] D) drying and calcining the solid after pressure filtration in step C);

[0011] E) removing iron from the material after calcination in step D) to obtain porcelain clay.

[0012] Preferably, in step A), the mass content of Na2O in the red mud is 6% to 10%, the mass content of Al2O3 is 22% to 27%, the mass content of SiO2 is 20% to 25%, the mass content of Fe2O3 is 7% to 12%, the mass content of TiO2 is 2% to 7%, the mass content of CaO is 11% to 16%, and the mass content of K2O is 1% to 2%; the Ca / S of the red mud is 0.3 to 0.8:1; and the N / S of the red mud is 0.1 to 0.6:1.

[0013] Preferably, in step A), the acid in the acid solution comprises at least one of hydrochloric acid, oxalic acid, phosphoric acid, and sulfuric acid.

[0014] The mass concentration of the acid solution is 2% to 12%.

[0015] Preferably, in step A), the mass ratio of the acid solution to the red mud is 6 to 12:1.

[0016] The mass concentration of the soluble salt in the salt solution is 0.5% to 1.2%.

[0017] Preferably, in step B), the amount of the compressed air is 4 to 30 kg / cm 2 ;

[0018] The mass content of the soluble salt in the filtrate after the pressure filtration is 0.5% to 1.2%.

[0019] Preferably, in step C), the mass ratio of the air-dried solid to water is 1:5 to 10.

[0020] The mass content of the soluble salt in the mixed solution is 0.065% to 0.14%.

[0021] Preferably, in step C), the mass content of water in the solid after the second pressure filtration is ≤50%.

[0022] The mass content of the soluble salt in the filtrate after the second pressure filtration is 0.07% to 0.15%.

[0023] Preferably, in step D), the drying temperature is 120 to 150°C; and the water content of the dried solid is 1% to 10%.

[0024] Preferably, in step D), the calcination temperature is 600 to 1200°C, and the time is 2 min to 2 h.

[0025] Preferably, in step E), after the iron removal, the mass content of iron in the porcelain clay is 2.5% to 3.5%.

[0026] The application provides application of red mud as a raw material for preparation of porcelain clay, and particularly, a preparation method of the porcelain clay comprises the following steps: A) mixing the red mud and an acid solution, and reacting to obtain a salt solution with a pH value of 4-6.8; B) performing pressure filtration on the solution obtained in step A), and controlling the mass content of water to be not higher than 50%; then introducing compressed air to perform air pressure drying; C) mixing the solid after the air pressure drying with water, and performing pressure filtration again; D) drying and calcining the solid after the pressure filtration in step C); and E) removing iron from the material after the calcination in step D) to obtain the porcelain clay. The applicant finds that, by treating the red mud according to the above steps, most of the substances in the red mud can be utilized, the porcelain clay with relatively good performance is prepared, and the generated waste residue and waste water are extremely small. BRIEF DESCRIPTION OF DRAWINGS

[0027] Fig. 1 is a particle size distribution diagram of the porcelain clay obtained in Example 1 of the application;

[0028] Fig. 2 is a particle size distribution diagram of the porcelain clay obtained in Example 2 of the application. DETAILED DESCRIPTION

[0029] The technical solutions of the application will be described clearly and completely in combination with the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0030] The application provides application of red mud as a raw material for preparation of porcelain clay.

[0031] The application further provides a preparation method of the porcelain clay, comprising the following steps:

[0032] A) mixing the red mud and an acid solution, and reacting to obtain a salt solution with a pH value of 4-6.8;

[0033] B) performing pressure filtration on the solution obtained in step A), and controlling the mass content of water to be not higher than 50%; then introducing compressed air to perform air pressure drying;

[0034] C) mixing the solid after the air pressure drying with water, and performing pressure filtration again;

[0035] D) drying and calcining the solid after the pressure filtration in step C);

[0036] E) removing iron from the material after the calcination in step D) to obtain the porcelain clay.

[0037] In step A):

[0038] The red mud and the acid solution are mixed and reacted to obtain a salt solution with a pH value of 4-6.8.

[0039] In some embodiments of the present invention, the red mud contains 6%–10% Na₂O, 22%–27% Al₂O₃, 20%–25% SiO₂, 7%–12% Fe₂O₃, 2%–7% TiO₂, 11%–16% CaO, and 1%–2% K₂O. The Ca / S (mass ratio) of the red mud is 0.3–0.8:1. The N / S (mass ratio) of the red mud is 0.1–0.6:1. The water content of the red mud is 10%–60%, for example, 39.9%.

[0040] In some embodiments of the present invention, the acid in the acid solution includes at least one selected from hydrochloric acid, oxalic acid, phosphoric acid, and sulfuric acid. The mass concentration of the acid solution is 2% to 12%, for example, 2%.

[0041] The mass ratio of the acid solution to the red mud is 6 to 12:1, for example, 8:1 or 6:1.

[0042] When water, red mud, and an acid solution are mixed, the sodium oxide in the red mud reacts with the acid to form a soluble salt. At this point, the red mud is completely dispersed in the solution, forming a slurry. The mass concentration of the soluble salt in the resulting salt solution is 0.5% to 1.2%, for example, 0.8% or 0.79%. Specifically, the pH value of the salt solution is 5.

[0043] The reaction temperature is 2–40°C, such as 35°C or 20°C; the time is 0.5–5 hours, such as 1 hour or 3 hours.

[0044] In step B):

[0045] The solution obtained in step A) is subjected to pressure filtration, and the mass content of the filter cake moisture is controlled to be no more than 50%; then compressed air is introduced to air-dry it.

[0046] The filtration is carried out in a plate and frame filter press. In some embodiments of the invention, the moisture content is controlled to be less than 40% by mass.

[0047] In some embodiments of the present invention, the amount of compressed air used is 4–30 kg / cm³. 2 For example, 20kg / cm 2 10kg / cm 2 .

[0048] In some embodiments of the present invention, the mass content of soluble salts in the filtrate after pressure filtration is 0.5% to 1.2%, such as 1.02% or 0.99%. The mass content of calcium chloride in the filtrate after pressure filtration is 0.01% to 0.12%, such as 0.01% or 0.096%.

[0049] In some embodiments of the present application, after the pressure filtration, further comprising: removing calcium chloride in the filtrate, and then performing reverse osmosis treatment.

[0050] The method for removing calcium chloride in the filtrate comprises:

[0051] The content of calcium chloride in the filtrate is determined by a calcium ion detector, sodium carbonate is added to generate calcium carbonate precipitate and sodium chloride, and the upper clear water is subjected to reverse osmosis treatment.

[0052] The molar ratio of the added sodium carbonate to the calcium chloride in the filtrate is 1:1.

[0053] After removing the calcium chloride in the filtrate, the mass content of calcium chloride in the filtrate is ≤400 ppm, such as 20 ppm.

[0054] After the reverse osmosis treatment, the mass content of soluble salt in the produced water is ≤150 ppm, such as 100 ppm, 150 ppm. The produced water after reverse osmosis can be reused in step C) and mixed with the air-dried solid. The mass content of soluble salt in the concentrated water after reverse osmosis is 5% to 12%, which is used for other purposes.

[0055] In step C):

[0056] The air-dried solid and water are mixed, and then pressure filtration is performed again.

[0057] In some embodiments of the present application, the mass ratio of the air-dried solid to water is 1:5 to 10, such as 1:6. The mass content of soluble salt in the mixed solution is 0.065% to 0.14%, such as 0.09%, 0.11%.

[0058] The present application mixes the air-dried solid with water to further remove soluble salt.

[0059] In some embodiments of the present application, the mass content of water in the solid after the second pressure filtration is ≤50%.

[0060] In some embodiments of the present application, the mass content of soluble salt in the filtrate after the second pressure filtration is 0.07% to 0.15%, such as 0.15%, 0.14%. The filtrate after the second pressure filtration can be reused in step A).

[0061] In step D):

[0062] The solid after the pressure filtration in step C) is dried and calcined.

[0063] In some embodiments of the present application, the drying temperature is 120 to 150°C, such as 130°C. The water content of the dried solid is 1% to 10%, such as 5.2%.

[0064] After the drying, the material is further crushed. The particle size of the crushed material is not more than 100 μm.

[0065] In some embodiments of the present application, the temperature of the calcination is 600-1200℃, such as 1000℃; and the time is 2 min-2 h, such as 1 h.

[0066] In step E), the material is further subjected to a de-ironing process.

[0067] The material after the calcination of step D) is subjected to a de-ironing process to obtain the porcelain clay.

[0068] The de-ironing process is not particularly limited in the present application. In some embodiments of the present application, the de-ironing process comprises:

[0069] The material is blown by a gas stream between a plurality of cylindrical magnetic rods to remove the iron.

[0070] The material is blown by a gas stream between a plurality of cylindrical magnetic rods. The material with strong magnetism is attracted by the magnetic rods, and the material with no or weak magnetism is blown away by the gas stream, thereby separating the two materials.

[0071] After the de-ironing process, the mass content of iron in the obtained porcelain clay is 2.5%-3.5%, such as 2.9%.

[0072] In some embodiments of the present application, in the porcelain clay, the mass content of Al2O3 is 33%-34%, the mass content of SiO2 is 29%-32%, the mass content of Fe2O3 is 9%-11%, the mass content of TiO2 is 6%-7%, the mass content of CaO is 6%-8%, and the mass content of Na2O is 0.6%-0.7%.

[0073] In order to further illustrate the present application, the application of the red mud as a raw material for the preparation of porcelain clay is described in detail in the following examples, but it should not be understood as a limitation on the scope of the present application.

[0074] The raw materials used in the following examples are commercially available.

[0075] Example 1

[0076] The red mud from a certain place in Shanxi Province was taken, and the water content was 39.9%.

[0077] The contents of some components in the red mud are shown in Table 1.

[0078] Table 1 Contents of some components in the red mud

[0079] Preparation of the porcelain clay:

[0080] 1) In a cylindrical tank, 96 tons of an acid solution (a mixed solution of hydrochloric acid and phosphoric acid) having a mass concentration of 2% was added, and then 12 tons of red mud was added, and reacted at 35°C for 1 hour to obtain a salt solution having a pH of 5; the mass concentration of soluble salt in the salt solution was 0.8%;

[0081] 2) The salt solution was sent to a plate-and-frame filter press for pressure filtration, and the mass content of water in the filter cake was controlled to be 50%; after the pressure filtration was completed, compressed air was introduced to perform air pressure drying; the amount of compressed air used was 20 kg / cm 2 ; the mass content of soluble salt in the filtrate after the pressure filtration was 1.02%, and the mass content of calcium chloride in the filtrate after the pressure filtration was 0.01%;

[0082] After the pressure filtration, the mass content of calcium chloride in the filtrate was determined by a calcium ion detector, and an equal molar amount of sodium carbonate was added to generate calcium carbonate precipitate and sodium chloride; the mass content of calcium chloride in the upper clear water was 20 ppm, and reverse osmosis treatment was performed; after the reverse osmosis treatment, the mass content of soluble salt in the product water was 100 ppm, and the product water was recycled to step 3); the mass content of soluble salt in the concentrated water after the reverse osmosis was 8%;

[0083] 3) The air pressure dried solid and water were mixed, and then a plate-and-frame filter press was used again for pressure filtration; the mass ratio of the air pressure dried solid to water was 1:6; the mass content of soluble salt in the mixed solution was 0.09%; the mass content of water in the solid after the second pressure filtration was 49.7%; the mass content of soluble salt in the filtrate after the second pressure filtration was 0.15%, and the filtrate was recycled to step 1);

[0084] 4) The solid after the pressure filtration in step 3) was dried at 130°C, and the weight was 8.71 kg, and the water content was 5.2%; the solid was crushed, and the particle size of the crushed particles was not more than 100 μm; then, the solid was calcined at 1000°C for 1 hour.

[0085] 5) The calcined solid in step 4) was subjected to iron removal by blowing the solid with airflow between a plurality of cylindrical magnetic rods to obtain china clay; the mass content of iron in the china clay was 2.9%.

[0086] Through detection, the residual waste was 0.61 kg, the yield of china clay was 84.2%, the solid conversion rate was 89.9%, and the amount of water used was 62 L.

[0087] Part of the components in the china clay are shown in Table 2.

[0088] Table 2 Part of the components in the china clay

[0089] From Table 1-2, after the red mud is treated by the present application, most of the alkali is removed, and the rest is reserved. The main components of the product are similar to those of porcelain clay, and the content of titanium oxide is higher, which has the effect of optimizing porcelain. From the various detection indexes, they all meet the requirements of porcelain clay.

[0090] The product porcelain clay is detected, and it is found that:

[0091] The mass content of soluble salt is 0.32% (the detection instrument is conductivity meter);

[0092] Ignition loss: 1.8% (the detection instrument is muffle furnace);

[0093] The bulk density of the product porcelain clay is 0.445 g / mL (the detection instrument is bulk density detector).

[0094] The average particle size of the product porcelain clay is 8.08 μm, which is equivalent to 1700 mesh, and the specific particle size distribution chart is shown in the following figure. Figure 1 is the particle size distribution chart of the porcelain clay obtained by the embodiment 1 of the present application.

[0095] The porcelain factory carried out application test on this sample, and the situation was good.

[0096] Embodiment 2

[0097] The components of the red mud are the same as those in embodiment 1.

[0098] Preparation of porcelain clay:

[0099] 1) In a round storage tank, 80 tons of acid solution (mixed solution of sulfuric acid and oxalic acid) with a mass concentration of 0.2% are added, and then 13 tons of red mud are added, and the reaction is carried out at 20°C for 3h to obtain a salt solution with a pH value of 6; the mass concentration of soluble salt in the salt solution is 0.79%;

[0100] 2) The salt solution is sent to a plate and frame filter press for pressure filtration, and the mass content of water in the filter cake is controlled to be 49.3%; after the pressure filtration is completed, compressed air is introduced for air pressure drying; the amount of compressed air used is 10 kg / cm 2 ; the mass content of soluble salt in the filtrate after pressure filtration is 0.99%, and the mass content of calcium chloride in the filtrate after pressure filtration is 0.096%;

[0101] After the pressure filtration, the content of calcium chloride in the filtrate is determined by a calcium ion detector, and an equal molar amount of sodium carbonate is added to generate calcium carbonate precipitate and sodium chloride, and the mass content of calcium chloride in the upper clear water is 20 ppm, which is subjected to reverse osmosis treatment; after the reverse osmosis treatment, the mass content of soluble salt in the product water is 150 ppm, and the product water is recycled to step 3);

[0102] 3) mixing the air-dried solid and water, and filtering again by using a plate-frame filter press; the mass ratio of the air-dried solid to water is 1:9; the mass content of soluble salt in the mixed solution is 0.11%; the mass content of water in the solid after the second filtration is 49.3%; the mass content of soluble salt in the filtrate after the second filtration is 0.14%, and the filtrate is used in step 1);

[0103] 4) drying the solid after the filtration in step 3) at 120℃, and obtaining 9.63 kg of solid with a water content of 4.8%; crushing the solid, and obtaining a particle size of the crushed solid of no more than 100 μm; and then, calcining the solid at 1200℃ for 30 min.

[0104] 5) removing iron from the calcined solid in step 4) by using airflow to blow the solid between a plurality of cylindrical magnetic rods, and obtaining 9.37 kg of porcelain clay; the mass content of iron in the porcelain clay is 3.0%.

[0105] It is detected that the residual waste is 0.56 kg, the yield of the porcelain clay is 85.2%, the solid conversion rate is 89.7%, and the water consumption is 68 L.

[0106] Part of the components in the porcelain clay are shown in Table 3.

[0107] Table 3 Part of the components in the porcelain clay

[0108] From Table 1 and Table 3, it can be seen that, after the red mud is treated according to the present application, most of the iron is removed, and other components are reserved. The main components of the finished product are similar to those of the porcelain clay, and the content of titanium oxide is high, which has an effect of optimizing porcelain. From the detection indexes, all meet the requirements of the porcelain clay.

[0109] It is detected that the residual waste is 0.56 kg, the yield of the porcelain clay is 85.2%, the solid conversion rate is 89.7%, and the water consumption is 68 L.

[0110] The mass content of soluble salt is 0.34% (the detection method is an electric conductivity meter);

[0111] The ignition loss is 2.0% (the detection instrument is a muffle furnace);

[0112] The bulk density of the finished porcelain clay is 0.451 g / mL (the detection instrument is a bulk density detector).

[0113] The average particle size of the finished porcelain clay is 10 μm, which is equivalent to 1600 meshes, and the particle size distribution is shown in the particle size distribution graph. Fig. 2 is a particle size distribution graph of the porcelain clay obtained in Example 2 of the present application.

[0114] The porcelain factory has carried out application tests on the sample, and the results are good.

[0115] The above description of the examples is merely intended to help understand the method of the present application and its core idea. Various modifications to these examples will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other examples without departing from the spirit or scope of the present application. Thus, the present application is not to be limited to the examples shown herein but is to accord with the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. Use of red mud as a raw material for the preparation of porcelain clay.

2. A method for preparing porcelain clay, comprising the following steps: A) mixing red mud and an acid solution to react, to obtain a salt solution with a pH value of 4-6.8; B) filtering the solution obtained in step A) by pressure filtration, to control the mass content of water to be no more than 50%; then passing compressed air to perform air pressure drying; C) mixing the solid after air pressure drying with water, and filtering again by pressure filtration; D) drying and calcining the solid after pressure filtration in step C); E) removing iron from the material after calcination in step D) to obtain porcelain clay.

3. The preparation method according to claim 1, characterized in that, In step A), the mass content of Na2O in the red mud is 6%-10%, the mass content of Al2O3 is 22%-27%, the mass content of SiO2 is 20%-25%, the mass content of Fe2O3 is 7%-12%, the mass content of TiO2 is 2%-7%, the mass content of CaO is 11%-16%, and the mass content of K2O is 1%-2%; the Ca / S of the red mud is 0.3-0.8:1; and the N / S of the red mud is 0.1-0.6:

1.

4. The method of claim 1, wherein, In step A), the acid in the acid solution comprises at least one of hydrochloric acid, oxalic acid, phosphoric acid, and sulfuric acid. The mass concentration of the acid solution is 2%-12%.

5. The preparation method according to claim 1, characterized in that, In step A), the mass ratio of the acid solution to red mud is 6-12:

1. The mass concentration of soluble salt in the salt solution is 0.5%-1.2%.

6. The method of claim 1, wherein, In step B), the amount of compressed air used is 4 to 30 kg / cm 2 ; The mass content of soluble salt in the filtrate after pressure filtration is 0.5%-1.2%.

7. The preparation method according to claim 1, characterized in that, In step C), the mass ratio of the solid after air pressure drying to water is 1:5-10. The mass content of soluble salt in the mixed solution is 0.065%-0.14%.

8. The method of claim 1, wherein, In step C), the mass content of water in the solid after re-filtering by pressure filtration is ≤50%. The mass content of soluble salt in the filtrate after re-filtering is 0.07%-0.15%.

9. The method of claim 1, wherein, In step D), the drying temperature is 120-150°C; and the water content in the solid after drying is 1%-10%. The calcination temperature is 600-1200°C, and the time is 2 min-2 h.

10. The method of claim 1, wherein, In step E), the mass content of iron in the porcelain clay obtained after iron removal is 2.5%-3.5%.

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