Method for removing sodium from red mud

Abstract

The invention provides a method for removing sodium from red mud, and belongs to the technical field of comprehensive utilization of red mud. The method comprises the following steps: taking citric acid waste liquid, waste ceramic powder and magnesium chloride as raw materials to obtain premixed liquid, mixing red mud slurry with the premixed liquid, carrying out primary sodium removal reaction, then adding ground phosphogypsum, carrying out secondary sodium removal reaction, separating out solids, and sequentially washing and drying to obtain the sodium-removed red mud. According to the method, the citric acid waste liquid and the phosphogypsum are utilized, soluble sodium is neutralized firstly, and then structural sodium is replaced, so that the sodium removal rate is greatly increased, and the problem of incomplete sodium removal in the prior art is solved. The method is low in raw material cost and high in system environment safety, and resource utilization of the red mud can be realized.

Description

Technical Field

[0001] This invention relates to the field of red mud comprehensive utilization technology, and in particular to a method for sodium removal from red mud. Background Technology

[0002] Red mud is a highly alkaline industrial waste produced during the extraction of alumina from bauxite. Its pH value is as high as 12-13, and its main alkaline components are sodium compounds such as caustic soda and sodium aluminate. Large accumulations of red mud not only occupy land resources, but their strong alkalinity also leads to serious environmental problems such as soil salinization and groundwater pollution, hindering the sustainable development of the alumina industry. Therefore, sodium removal from red mud is a prerequisite for its resource utilization.

[0003] Existing methods for red mud dealkali removal mainly include calcium-based dealkali removal, carbonization-based dealkali removal, and acid-based dealkali removal. Among them, acid-based dealkali removal has received widespread attention due to its simple operation, low economic cost, and good dealkali removal effect. In particular, the technical approach of co-treating red mud with acidic waste gas and waste acid can achieve "waste treatment with waste," further reducing treatment costs and becoming an ideal direction for dealkali removal. However, existing acid-based dealkali removal technologies still have many drawbacks: for example, the method disclosed in patent CN118957269A requires the use of large amounts of strong acid and alkali, resulting in a large initial acid input and high costs. Furthermore, the enrichment and concentration process requires multiple enrichment stages, making it complex and time-consuming. Patent CN108640446A uses a composite organic acid system, which has low corrosivity, but the wood vinegar used has unstable components, and aminosulfonic acid is prone to hydrolysis at high temperatures to produce ammonium sulfate impurities. The EDTA complexing agent is also too expensive. Patent CN112723688A uses concentrated sulfuric acid as a dealkalizing agent, which is extremely corrosive, poses a high operational risk, and has harsh process conditions. The combined dealkalization method disclosed in CN113262422A has the problem of low sodium removal rate, making it difficult to meet the requirements for the resource utilization of red mud.

[0004] Therefore, it is of great significance to develop a low-cost, highly safe, high-sodium-removal-rate, and environmentally friendly red mud sodium removal technology. Summary of the Invention

[0005] The purpose of this invention is to provide a method for removing sodium from red mud, so as to solve the problems of incomplete sodium removal, high cost, and unsafe use in existing technologies.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for sodium removal from red mud, comprising the following steps:

[0008] Red mud is mixed with water to obtain red mud slurry;

[0009] Citric acid waste liquid, waste ceramic powder and magnesium chloride are mixed, and the resulting premixed liquid is mixed with the red mud slurry to carry out a first-stage desodiuming reaction to obtain a first-stage reaction system.

[0010] Grinded phosphogypsum was added to the primary reaction system to carry out a secondary desodiuming reaction, resulting in a secondary reaction system.

[0011] The secondary reaction system was separated and then washed and dried to obtain sodium-free red mud.

[0012] Preferably, the red mud has a particle size of 80-100 mesh, and the mass ratio of the red mud to water is 1:(5-7).

[0013] Preferably, based on the total mass of citric acid waste liquid, waste ceramic powder, magnesium chloride, and ground phosphogypsum as 100%, the mass fraction of the citric acid waste liquid is 60-70%, the mass fraction of the waste ceramic powder is 1-10%, the mass fraction of the magnesium chloride is 3-8%, and the mass fraction of the phosphogypsum is 20-30%.

[0014] Preferably, the citric acid in the citric acid waste liquid has a mass concentration of 8-12%; and the particle size of the waste ceramic powder is 200-300 mesh.

[0015] Preferably, the mass ratio of the premixed liquid to the red mud slurry is (1-3):10.

[0016] Preferably, the temperature of the primary sodium removal reaction is 25–60°C, the stirring rate is 200–500 rpm, and the time is 1–2 h.

[0017] Preferably, the ground phosphogypsum is obtained by grinding phosphogypsum, and the grinding speed is 800-1500 rpm, the temperature is 20-30℃, and the time is 15-30 min;

[0018] The particle size of the ground phosphogypsum is 150-200 mesh.

[0019] Preferably, the temperature of the secondary desodium removal reaction is 25–60°C, the stirring rate is 200–500 rpm, and the time is 2–4 h;

[0020] The pH of the secondary reaction system is 6-7.

[0021] Preferably, the washing is performed 2 to 3 times, and the liquid-to-solid ratio of the washing is (2 to 3):1.

[0022] Preferably, the drying temperature is 80–105°C and the drying time is 4–6 hours.

[0023] The beneficial effects of this invention are:

[0024] This invention prepares a red mud desodiuming agent using citric acid waste liquid, phosphogypsum, waste ceramic powder, and magnesium chloride as raw materials. On one hand, the H in the citric acid waste liquid... + It undergoes a neutralization reaction with soluble alkali, converting the sodium in the soluble alkali into sodium citrate, which then enters the filtrate. On the other hand, the calcium ions provided by phosphogypsum and the magnesium ions provided by magnesium chloride target and attack the crystal lattice structure of the chemically bound alkali through ion exchange, displacing the sodium in the crystal lattice. + It generates stable calcium nepheline; by first neutralizing soluble sodium and then replacing structural sodium, the sodium removal rate can reach over 90%, solving the problem of incomplete sodium removal in existing technologies.

[0025] The raw materials for this invention are citric acid waste liquid and phosphogypsum, which are low in cost and achieve waste treatment, significantly reducing raw material costs. The entire system is a mild organic acid environment with high operational safety. The reaction endpoint pH is 6-7, and the effluent is mainly sodium citrate and calcium citrate solution, which are non-toxic and biodegradable, achieving zero pollution discharge. Detailed Implementation

[0026] This invention provides a method for sodium removal from red mud, comprising the following steps:

[0027] Red mud is mixed with water to obtain red mud slurry;

[0028] Citric acid waste liquid, waste ceramic powder and magnesium chloride are mixed, and the resulting premixed liquid is mixed with the red mud slurry to carry out a first-stage desodiuming reaction to obtain a first-stage reaction system.

[0029] Grinded phosphogypsum was added to the primary reaction system to carry out a secondary desodiuming reaction, resulting in a secondary reaction system.

[0030] The secondary reaction system was separated and then washed and dried to obtain sodium-free red mud.

[0031] In this invention, unless otherwise specified, all raw materials required for preparation are commercially available products well known to those skilled in the art.

[0032] The present invention preferably involves drying the red mud in an oven at 80–105°C for 4–6 hours to remove free moisture, then crushing it to a particle size of 80–100 mesh using a crusher, and finally mixing it with water to obtain a red mud slurry.

[0033] In this invention, the red mud preferably includes Bayer process red mud, and the sodium oxide content in the red mud is preferably 8-12% by mass, more preferably 10%.

[0034] In this invention, the mass ratio of red mud to water is preferably 1:(5-7), and more preferably 1:6.

[0035] This invention preferably involves mixing citric acid waste liquid, waste ceramic powder, and magnesium chloride. The resulting premixed solution is then mixed with the red mud slurry and the premixed solution to perform a primary sodium removal reaction, yielding a primary reaction system. During the primary sodium removal reaction, the H+ in the citric acid waste liquid... + It preferentially undergoes a neutralization reaction with soluble alkali in red mud, converting soluble sodium into sodium citrate which enters the liquid phase, thereby increasing the sodium removal rate.

[0036] In this invention, taking the total mass of citric acid waste liquid, waste ceramic powder, magnesium chloride, and ground phosphogypsum as 100%, the mass fraction of the citric acid waste liquid is preferably 60-70%, more preferably 65-70%; the mass fraction of the waste ceramic powder is preferably 1-10%, more preferably 2-10%; the mass fraction of the magnesium chloride is preferably 3-8%, more preferably 4-6%; and the mass fraction of the ground phosphogypsum is preferably 20-30%, more preferably 25-30%.

[0037] In this invention, the citric acid waste liquid is preferably a byproduct from a citric acid production enterprise or a juice processing plant, and the mass concentration of citric acid in the citric acid waste liquid is preferably 8-12%, more preferably 10-12%.

[0038] In this invention, the waste ceramic powder is preferably derived from waste generated during ceramic production. The particle size of the waste ceramic powder is preferably 200-300 mesh, more preferably 250-300 mesh. The waste ceramic powder has a high specific surface area and is an inert chemical substance. When mixed into the reaction system, it can be uniformly dispersed in the red mud slurry, which helps reduce red mud agglomeration. Its rigid particle characteristics help reduce the sedimentation of red mud particles and accelerate the reaction of H+ in citric acid waste liquid. + The increased mass transfer efficiency with soluble sodium in red mud allows for a more complete first-order neutralization reaction.

[0039] In this invention, the mass ratio of the red mud slurry to the premixed liquid is preferably 10:(1-3), and more preferably 10:2.

[0040] In this invention, the temperature of the primary sodium removal reaction is preferably 25-60°C, more preferably 40-60°C, the stirring rate is preferably 200-500 rpm, more preferably 300-500 rpm, and the time is preferably 1-2 h, more preferably 1.5-2 h.

[0041] Preferably, after the first-stage reaction is completed, ground phosphogypsum is added to the reactor, and the temperature and stirring rate are kept constant to carry out the second-stage desodiuming reaction; the phosphogypsum provides Ca... 2+ With magnesium chloride providing Mg 2+ By attacking the crystal lattice structure of chemically bound bases through ion exchange, Na is displaced from the crystal lattice. +It also generates stable calcium nepheline, further improving the sodium removal rate. Among them, the magnesium ion radius of magnesium chloride is smaller than that of calcium ions in phosphogypsum, so it can preferentially penetrate into the dense sodium-containing lattice in red mud, replacing some of the structural sodium. The calcium ions then combine with lattice vacancies to generate more stable calcium aluminate. The two form a dual-cation synergistic system, thereby improving the removal rate of structural sodium.

[0042] In this invention, the ground phosphogypsum is preferably obtained by grinding phosphogypsum. The grinding speed is preferably 800-1500 rpm, more preferably 850-1000 rpm, and even more preferably 900 rpm. The temperature is preferably 20-30℃, more preferably 25-30℃, and the time is preferably 15-30 min, more preferably 20-25 min.

[0043] In this invention, the particle size of the ground phosphogypsum is preferably 150-200 mesh, and more preferably 160-180 mesh.

[0044] In this invention, the temperature of the secondary desodium reaction is preferably 25-60°C, more preferably 40-60°C, the stirring rate is preferably 200-500 rpm, more preferably 300-500 rpm, and the time is preferably 2-4 h, more preferably 3-4 h.

[0045] In this invention, the solid is preferably separated after the secondary desodiuming reaction is completed, washed with water to remove residual soluble salts on the surface, and dried to obtain desodiumed red mud; the filtrate is sent to an evaporator for evaporation and concentration, cooled and crystallized to recover industrial-grade sodium citrate, and the remaining mother liquor is evaporated again to precipitate salt and obtain industrial-grade sodium chloride.

[0046] In this invention, the number of washing cycles is preferably 2 to 3 times, more preferably 2 times, and the liquid-to-solid ratio of the washing is preferably (2 to 3):1, more preferably 2:1.

[0047] In this invention, the drying temperature is preferably 80-105°C, more preferably 90°C, and the drying time is preferably 4-6 hours, more preferably 5-6 hours.

[0048] In this invention, the evaporation and concentration temperature is preferably 70-80°C, more preferably 75°C, and the solid content of the filtrate after evaporation and concentration is preferably 20-30%, more preferably 22-28%. The cooling and crystallization temperature is preferably 0-10°C, more preferably 0-8°C, and the time is preferably 4-8 hours, more preferably 6-8 hours.

[0049] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0050] The red mud used in Examples 1-3 and Comparative Examples 1-3 was Bayer process red mud, in which the mass content of sodium oxide was 10%.

[0051] The citric acid waste liquid is a byproduct of citric acid production.

[0052] The waste ceramic powder comes from waste generated during the ceramic production process;

[0053] Example 1

[0054] Taking the total mass of citric acid waste liquid, waste ceramic powder, magnesium chloride, and ground phosphogypsum as 100%, the mass percentages of the raw materials used in this embodiment are as follows:

[0055] The waste liquid is composed of 65% citric acid (10% citric acid concentration), 30% phosphogypsum, 2% waste ceramic powder (200 mesh particle size), and 3% magnesium chloride.

[0056] The red mud was dried in a 100℃ oven for 5 hours and then crushed to a particle size of 80 mesh. It was then mixed with water at a liquid-to-solid ratio of 6:1 to obtain red mud slurry.

[0057] Citric acid waste liquid, waste ceramic powder and magnesium chloride were weighed according to mass fraction, mixed evenly to obtain a premixed liquid, and the obtained premixed liquid was mixed with red mud slurry at a ratio of 1:5. The mixture was reacted at 40℃ and 300 rpm for 1.5 h to obtain a first-order reaction system.

[0058] The phosphogypsum was ground at 850 rpm and 25°C for 20 min to obtain ground phosphogypsum with a particle size of 160 mesh. The ground phosphogypsum was added to the primary reaction system and the reaction was continued at 40°C and 300 rpm for 3 h. The final pH was 6.5, and the secondary reaction system was obtained.

[0059] Separate the secondary reaction system, wash the solid twice with water at a liquid-to-solid ratio of 2:1, and dry it at 90℃ for 5 hours to obtain desodium-removed red mud; evaporate and concentrate the filtrate at 75℃, cool and crystallize at 8℃ for 6 hours to recover industrial-grade sodium citrate, at which point the solid content of the filtrate is 22%; continue to evaporate the remaining mother liquor to precipitate salt and obtain industrial-grade sodium chloride.

[0060] Example 2

[0061] Taking the total mass of citric acid waste liquid, waste ceramic powder, magnesium chloride, and ground phosphogypsum as 100%, the mass percentages of the raw materials used in this embodiment are as follows:

[0062] The waste liquid is composed of 70% citric acid (12% citric acid concentration), 25% phosphogypsum, 2% waste ceramic powder (250 mesh particle size), and 6% magnesium chloride.

[0063] The red mud was dried in a 100℃ oven for 5 hours and then crushed to a particle size of 80 mesh. It was then mixed with water at a liquid-to-solid ratio of 6:1 to obtain red mud slurry.

[0064] Citric acid waste liquid, waste ceramic powder and magnesium chloride were weighed according to mass fraction, mixed evenly to obtain a premixed liquid, and the obtained premixed liquid was mixed with red mud slurry at a ratio of 1:5. The mixture was reacted at 40℃ and 300 rpm for 1.5 h to obtain a first-order reaction system.

[0065] The phosphogypsum was ground at 900 rpm and 25°C for 20 min to obtain ground phosphogypsum with a particle size of 180 mesh. The ground phosphogypsum was added to the primary reaction system and the reaction was continued at 40°C and 300 rpm for 3 h. The final pH was 6.5, and the secondary reaction system was obtained.

[0066] Separate the secondary reaction system, wash the solid twice with water at a liquid-to-solid ratio of 2:1, and dry it at 90℃ for 5 hours to obtain desodium-removed red mud; evaporate and concentrate the filtrate at 75℃, cool and crystallize at 8℃ for 6 hours to recover industrial-grade sodium citrate, at which point the solid content of the filtrate is 22%; continue to evaporate the remaining mother liquor to precipitate salt and obtain industrial-grade sodium chloride.

[0067] Example 3

[0068] Taking the total mass of citric acid waste liquid, waste ceramic powder, magnesium chloride, and ground phosphogypsum as 100%, the mass percentages of the raw materials used in this embodiment are as follows:

[0069] The waste liquid is composed of 60% citric acid (8% by mass), 20% phosphogypsum, 1% waste ceramic powder (300 mesh particle size), and 4% magnesium chloride.

[0070] The red mud was dried in a 100℃ oven for 5 hours and then crushed to a particle size of 80 mesh. It was then mixed with water at a liquid-to-solid ratio of 6:1 to obtain red mud slurry.

[0071] Citric acid waste liquid, waste ceramic powder and magnesium chloride were weighed according to mass fraction, mixed evenly to obtain a premixed liquid, and the obtained premixed liquid was mixed with red mud slurry at a ratio of 1:5. The mixture was reacted at 40℃ and 300 rpm for 1.5 h to obtain a first-order reaction system.

[0072] The phosphogypsum was ground at 1000 rpm and 30°C for 25 min to obtain ground phosphogypsum. The ground phosphogypsum was added to the primary reaction system and the reaction was continued at 40°C and 300 rpm for 3 h. The final pH was 6.5, and the secondary reaction system was obtained.

[0073] Separate the secondary reaction system, wash the solid twice with water at a liquid-to-solid ratio of 2:1, and dry it at 90℃ for 5 hours to obtain desodium-removed red mud; evaporate and concentrate the filtrate at 75℃, cool and crystallize at 8℃ for 6 hours to recover industrial-grade sodium citrate, at which point the solid content of the filtrate is 22%; continue to evaporate the remaining mother liquor to precipitate salt and obtain industrial-grade sodium chloride.

[0074] Comparative Example 1

[0075] The only difference from Example 2 is that:

[0076] No phosphogypsum was added; all other parameters were the same as in Example 2.

[0077] During sodium removal, the red mud is dried in a 100℃ oven for 5 hours and then crushed to a particle size of 80 mesh. It is then mixed with water at a liquid-to-solid ratio of 6:1 to obtain red mud slurry.

[0078] Citric acid waste liquid, waste ceramic powder and magnesium chloride were weighed according to mass fraction, mixed evenly to obtain a premixed liquid, and the obtained premixed liquid was mixed with red mud slurry at a ratio of 1:5. The mixture was reacted at 40℃ and 300 rpm for 4.5 h to obtain a first-order reaction system.

[0079] Separate the primary reaction system, wash the solid twice with water at a liquid-to-solid ratio of 2:1, and dry it at 90℃ for 5 hours to obtain desodium-removed red mud; evaporate and concentrate the filtrate at 75℃, cool and crystallize at 8℃ for 6 hours to recover industrial-grade sodium citrate, at which point the solid content of the filtrate is 22%; continue to evaporate the remaining mother liquor to precipitate salt and obtain industrial-grade sodium chloride.

[0080] Comparative Example 2

[0081] The only difference from Example 2 is that:

[0082] During sodium removal, the red mud is dried in a 100℃ oven for 5 hours and then crushed to a particle size of 80 mesh. It is then mixed with water at a liquid-to-solid ratio of 6:1 to obtain red mud slurry.

[0083] Citric acid waste liquid, waste ceramic powder, magnesium chloride and phosphogypsum were weighed according to mass fraction. The phosphogypsum was ground at 900 rpm and 25℃ for 20 min to obtain ground phosphogypsum with a particle size of 180 mesh. The citric acid waste liquid, waste ceramic powder, magnesium chloride and ground phosphogypsum were mixed evenly to obtain a premixed liquid. The obtained premixed liquid was mixed with red mud slurry at a ratio of 1:5 and reacted at 40℃ and 300 rpm for 4.5 h to obtain a first-order reaction system.

[0084] Separate the primary reaction system, wash the solid twice with water at a liquid-to-solid ratio of 2:1, and dry it at 90℃ for 5 hours to obtain desodium-removed red mud; evaporate and concentrate the filtrate at 75℃, cool and crystallize at 8℃ for 6 hours to recover industrial-grade sodium citrate, at which point the solid content of the filtrate is 22%; continue to evaporate the remaining mother liquor to precipitate salt and obtain industrial-grade sodium chloride.

[0085] Comparative Example 3

[0086] The combined dealkali removal agent disclosed in patent CN113262422A was used as the sodium removal agent for red mud in Comparative Example 3;

[0087] During sodium removal, the red mud is dried in a 100℃ oven for 5 hours and then crushed to a particle size of 80 mesh. It is then mixed with water at a liquid-to-solid ratio of 6:1 to obtain red mud slurry.

[0088] The obtained red mud slurry was mixed with red mud desodiuming agent and reacted at 40℃ and 300rpm for 4.5h, with an endpoint pH of 6.5.

[0089] The red mud was washed twice with a liquid-to-solid ratio of 2:1 and dried at 90°C for 5 hours to obtain sodium-free red mud.

[0090] Desodium removal effect determination

[0091] The sodium residue rate, sodium removal rate, and purity of recovered sodium citrate and sodium chloride in the red mud after sodium removal treatment by the red mud desodium removal agent in Examples 1-3 and Comparative Examples 1-3 were tested respectively. The results are shown in Table 1.

[0092] Table 1. Sodium removal results of Examples 1-3 and Comparative Examples 1-3

[0093] Sodium residue / % Sodium removal rate / % Sodium citrate purity / % Sodium chloride purity / % Example 1 0.83 91.7 97.2 92.5 Example 2 0.59 94.1 98.7 93.1 Example 3 0.82 91.8 96.5 91.3 Comparative Example 1 2.98 75.1 97.1 92.1 Comparative Example 2 1.77 82.3 92.6 89.8 Comparative Example 3 2.15 78.5 - -

[0094] As shown in Examples 1-3 and Table 1, the sodium removal rate of Examples 1-3 all reached over 91.7%, with Example 2 achieving the highest sodium removal rate of 94.1%, corresponding to a sodium content as low as 0.59% in the desodiumed red mud. This achieved deep removal of soluble sodium and structural sodium. Furthermore, the purity of the industrial-grade sodium citrate recovered after treatment with the red mud desodiuming agent in Examples 1-3 was all above 96.5%, and the purity of sodium chloride was all not less than 91.3%. The purity of the products met the industrial application standards, achieving efficient recovery of sodium resources.

[0095] As can be seen from Comparative Example 1 and Table 1, compared with Example 2, the sodium removal rate of Comparative Example 1 decreased to 75.1% after omitting phosphogypsum, and the sodium content in the desodiumed red mud increased to 2.98%, while the purity of sodium citrate and sodium chloride only decreased slightly. This indicates that phosphogypsum does indeed significantly reduce the sodium removal rate, resulting in incomplete sodium removal.

[0096] As shown in Comparative Example 2 and Table 1, compared with Example 2, Comparative Example 2, by simultaneously adding the premix and phosphogypsum to the red mud slurry, resulted in a sodium removal rate of 82.3%, an increase in the sodium content of the desodiumned red mud to 1.77%, and a decrease in the purity of sodium citrate to 92.6%. This is because the phosphogypsum reacted prematurely with the citric acid in the premix to form calcium citrate, consuming the effective sodium removal component (H). + This not only reduced the sodium removal efficiency but also affected the purity of sodium citrate recovery. This indicates that grinding phosphogypsum separately and adding it in steps can effectively avoid side reactions and is a key process step to ensure sodium removal efficiency and product purity.

[0097] As shown in Comparative Example 3 and Table 1, its red mud desodiuming agent achieved a desodiuming rate of only 78.5%, with a sodium content in the desodiumed red mud as high as 2.15%, and sodium citrate and sodium chloride could not be recovered. Compared with Examples 1-3, the desodiuming rate differed by up to 15.6%, and there was a lack of product resource utilization pathways. These results clearly demonstrate that the present invention, through a red mud desodiuming agent with a specific composition, improves the desodiuming efficiency and achieves product resource utilization, solving the problems of incomplete desodiuming and low desodiuming rate in existing technologies.

[0098] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for sodium removal from red mud, characterized in that, Includes the following steps: Red mud is mixed with water to obtain red mud slurry; Citric acid waste liquid, waste ceramic powder and magnesium chloride are mixed, and the resulting premixed liquid is mixed with the red mud slurry to carry out a first-stage desodiuming reaction to obtain a first-stage reaction system. Grinded phosphogypsum was added to the primary reaction system to carry out a secondary desodiuming reaction, resulting in a secondary reaction system. The secondary reaction system was separated and then washed and dried to obtain sodium-free red mud.

2. The method according to claim 1, characterized in that, The red mud has a particle size of 80-100 mesh, and the mass ratio of the red mud to water is 1:(5-7).

3. The method according to claim 1, characterized in that, Based on the total mass of citric acid waste liquid, waste ceramic powder, magnesium chloride, and ground phosphogypsum as 100%, the mass fraction of the citric acid waste liquid is 60-70%, the mass fraction of the waste ceramic powder is 1-10%, the mass fraction of the magnesium chloride is 3-8%, and the mass fraction of the phosphogypsum is 20-30%.

4. The method according to claim 3, characterized in that, The citric acid waste liquid has a citric acid concentration of 8-12% by mass; the waste ceramic powder has a particle size of 200-300 mesh.

5. The method according to claim 1, characterized in that, The mass ratio of the premixed liquid to the red mud slurry is (1-3):

10.

6. The method according to claim 5, characterized in that, The temperature of the primary sodium removal reaction is 25–60°C, the stirring rate is 200–500 rpm, and the time is 1–2 h.

7. The method according to claim 1, characterized in that, The ground phosphogypsum is obtained by grinding phosphogypsum. The grinding speed is 800-1500 rpm, the temperature is 20-30℃, and the time is 15-30 min. The particle size of the ground phosphogypsum is 150-200 mesh.

8. The method according to claim 7, characterized in that, The secondary desodium removal reaction is carried out at a temperature of 25–60°C, a stirring rate of 200–500 rpm, and a time of 2–4 h. The pH of the secondary reaction system is 6-7.

9. The method according to claim 1, characterized in that, The washing is performed 2 to 3 times, and the liquid-to-solid ratio of the washing is (2 to 3):

1.

10. The method according to claim 1, characterized in that, The drying temperature is 80–105°C, and the time is 4–6 hours.