Polytitanium composite coagulant as well as preparation method and application thereof

Abstract

The invention discloses a polytitanium composite coagulant as well as a preparation method and application thereof, and relates to the technical field of solid waste treatment. The preparation method of the poly-titanium composite coagulant comprises the following steps: S1, roasting and activating: sufficiently mixing titanium dioxide waste residues and concentrated sulfuric acid, roasting and activating; s2, acid dissolution leaching: mixing the roasted activated slag obtained in the step S1 with dilute sulphuric acid for reaction, and performing solid-liquid separation to obtain reaction mother liquor; s3, polymerizing and curing: adding calcium aluminate powder into the reaction mother liquor in the S2 to adjust the basicity of the solution, reacting and curing, and then carrying out solid-liquid separation to obtain the poly-titanium composite coagulant. According to the preparation method of the poly-titanium composite coagulant, the titanium dioxide waste residues serve as the raw material, TiO2 resources in the titanium dioxide waste residues are fully recycled through the roasting activation and acid dissolution leaching technology, meanwhile, aluminum, iron and calcium elements are introduced for synergistic interaction, the turbidity removal and decoloration effects are good, and the poly-titanium composite coagulant has the more excellent coagulation effect on papermaking, spinning and printing and dyeing wastewater treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste treatment, and more specifically, to a poly-titanium composite coagulant, a preparation method thereof, and an application thereof. Background Art

[0002] Titanium white waste residue is a solid waste generated in the production process of titanium dioxide. Its composition is relatively complex, mainly including undecomposed rutile-type titanium ore, incompletely decomposed anatase-type titanium ore and ilmenite, ores such as white stone, long strip stone, and quartz sand that do not react with acid, and silicon-aluminum colloid that coagulates and settles during the flocculation process of titanium liquid. The raw materials used in domestic sulfuric acid process titanium dioxide production are mainly titanium concentrate with a TiO2 content of about 46%, and the acidolysis rate is about 90%. The titanium dioxide content in the generated waste residue is 10-30%. According to statistics, for every 1 ton of titanium dioxide produced, 0.2-0.3 tons of titanium white waste residue will be generated. Due to the large output of the waste residue and the high treatment cost, enterprises generally dispose of it by means of abandonment and landfill, which not only wastes resources but also causes secondary pollution to the environment. Therefore, how to reasonably collect and utilize the titanium-containing materials in titanium white waste residue has become a research hotspot in titanium dioxide production technology. The titanium-containing materials in titanium white waste residue are relatively high, but the existing treatment methods for waste residue mostly involve pulping and neutralizing it to obtain titanium gypsum. The utilization value of titanium gypsum itself is very limited. About 6.5-9 tons of titanium gypsum are generated for every 1 ton of titanium dioxide produced. The discharge of titanium gypsum not only occupies a large amount of land, causes environmental pollution, and increases the economic burden of enterprises, but also wastes the TiO2 in it. Therefore, developing a new treatment method for titanium white waste residue, efficiently utilizing the titanium resources in it, saving production costs, and realizing the recycling of titanium resources have become urgent problems to be solved at present. For the recovery of titanium resources in low-titanium titanium white waste residue, currently there are mainly flotation method, magnetic separation method, mechanical activation method, and concrete method, etc. Although the flotation method and the magnetic separation method can increase the titanium dioxide content, they do not change the property that the waste residue is difficult to dissolve in acid in principle, and the utilization rate is low. Therefore, this type of screening method has great limitations and is not convenient for industrial application; although the mechanical activation method has a high leaching rate or a good enrichment effect, it has the disadvantages of large equipment wear and high treatment cost; the concrete method will be affected by factors such as the relatively low price of cement, the relatively high ball milling particle size requirements for low-titanium slag, and certain mixing ratio limitations, so it also has certain difficulties in industrialization. To sum up, the current comprehensive utilization technologies of titanium white waste residue resources all have deficiencies such as complex processes, low titanium resource utilization efficiency, high cost, and low regeneration value. Therefore, it is extremely urgent to seek a simple, economical, energy-saving, environmentally friendly, and high-regeneration-value treatment and disposal process for titanium-containing waste residue.

[0003] The prior art discloses a method for preparing a poly(hydroxychlorinated ferric aluminum calcium magnesium) coagulant, comprising the following steps: (a) mixing a filtrate obtained after solid-liquid separation of a chlorinated waste residue solution with a metal element, and performing a replacement reaction. After the reaction, the solid-liquid separation is performed to obtain a filtrate that has undergone preliminary impurity removal; (b) mixing the filtrate obtained in step (a) with an oxidant, and performing a Fe 2+ Oxidation reaction, followed by solid-liquid separation, to obtain Fe 3+ (c), the step (b) containing Fe 3+ The solution is combined with aluminum chloride and a stabilizer to undergo hydrolysis and polymerization reactions. After the reaction is completed, a poly(hydroxy)ferric aluminum calcium magnesium chloride coagulant is obtained; wherein the molecular formula of the poly(hydroxy)ferric aluminum calcium magnesium chloride coagulant is [Fe x (OH) 3xB Cl 3x(1-B) ·Al y (OH) 3yB Cl 3y(1-B) ·Ca z (OH) 2zB Cl 2z(1-B) Mg w (OH) 2wB Cl 2w(1-B) ] n ·mH2O; in step (a), the chlorinated waste residue solution includes waste generated by the chlorination process for producing titanium dioxide, and the chlorinated waste residue solution includes: Fe 2+ , Fe 3+ , Ca 2+ Mg 2+ and Cl - The prior art utilizes titanium dioxide waste residue recovery to prepare polyhydroxyferric aluminum calcium magnesium coagulant, which can be used to reduce water turbidity. However, the titanium dioxide waste residue recovery method does not achieve efficient and high-value recovery of titanium resources such as TiO2 in titanium dioxide waste residue recovery. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects and shortcomings of the existing titanium dioxide waste slag recovery method that fails to achieve efficient and high-value recovery of titanium resources such as TiO2 in the titanium dioxide waste slag recovery, and to provide a preparation method of a poly-titanium composite coagulant. The titanium dioxide waste slag is used as a raw material, and the TiO2 resources in the titanium dioxide waste slag are fully recovered by the "roasting activation + acid leaching" process to prepare a poly-titanium composite coagulant with excellent COD removal effect and turbidity reduction effect.

[0005] Another object of the present invention is to provide a poly-titanium composite coagulant.

[0006] Another object of the present invention is to provide an application of a poly-titanium composite coagulant in water treatment.

[0007] The above object of the present invention is achieved by the following technical solutions:

[0008] A preparation method of a poly-titanium composite coagulant, comprising the following steps:

[0009] S1. Roasting activation: fully mix titanium white waste residue with concentrated sulfuric acid, place it in a roasting activation at 250 - 300 °C for 2 - 3 h, and cool to obtain roasted activated slag;

[0010] S2. Acid dissolution leaching: mix the roasted activated slag in S1 with dilute sulfuric acid, react at 70 - 80 °C for 1 - 2 h, then add aluminum-containing sludge, keep the temperature for reaction for 0.5 - 1 h, and after the reaction is complete, perform solid-liquid separation to obtain the reaction mother liquor;

[0011] S3. Polymerization ripening: add calcium aluminate powder to the reaction mother liquor in S2, react at 85 - 95 °C for 1 - 2 h and take out, after ripening at room temperature, perform solid-liquid separation to obtain a poly-titanium composite coagulant with a basicity of 20 - 40 wt%,

[0012] The addition amount of calcium aluminate powder in S3 is 2 - 4% of the mass of the reaction mother liquor.

[0013] Among them, it should be noted that:

[0014] The solution basicity of the present invention refers to:

[0015] The index for measuring OH ions in the flocculant is called basicity (abbreviated as B), and usually the basicity is defined as the equivalent percentage of OH to metal ions in the flocculant molecule ([OH] / [metal ions] × 100 (%)).

[0016] In the preparation method of the poly-titanium composite coagulant of the present invention, titanium compounds in the waste residue are difficult to leach by conventional reactions. In S1, through high-temperature roasting at 250 - 300 °C and the action of concentrated sulfuric acid, insoluble TiO2 is transformed into soluble titanium sulfates, such as titanyl sulfate and titanium sulfate, so as to facilitate the subsequent leaching and recovery of titanium resources. The synergistic effect of the roasting activation temperature and time can not only control the decomposition of sulfuric acid but also ensure the full reaction and improve the conversion and leaching rate of titanium resources.

[0017] In step S2, the continuous use of dilute sulfuric acid reaction is to leach the soluble titanium after roasting activation, so that titanium resources can fully enter the solution system for recovery, and the adequacy and completeness of the leaching reaction are ensured through the synergistic control of the leaching temperature and time.

[0018] The preparation method of the poly-titanium composite coagulant of the present invention uses titanium white waste residue as the raw material, and utilizes the "roasting activation + acid dissolution leaching" process to fully recover TiO2 resources in the titanium white waste residue, transform them into soluble titanium sulfates for acid dissolution leaching, and realize the maximum value of the coordinated disposal and resource utilization of waste.

[0019] Meanwhile, in the preparation method of the poly-titanium composite coagulant of the present invention, elements such as aluminum, iron, and calcium are introduced for synergistic enhancement, and the poly-titanium composite coagulant is comprehensively utilized, making up for the defects of traditional inorganic flocculants such as large dosage and small flocs. It has the advantages of fast floc formation, large and dense particles, fast floc sedimentation speed, good turbidity removal and decolorization effects, and shows more excellent coagulation effects in the treatment of papermaking, textile, and printing and dyeing wastewater.

[0020] The preparation method of the poly-titanium composite coagulant of the present invention also has the advantages of simple process, safety and environmental protection, short process, low energy consumption, strong operability, treating waste with waste, green environmental protection, small environmental pollution, and remarkable economy, and is convenient for the transformation of industrialization achievements.

[0021] In the specific embodiment, the titanium white waste residue of the present invention is preferably dried, ground, and sieved, and the preferred sieve aperture is 80-100 meshes.

[0022] In the specific embodiment, in order to make the reaction more sufficient and the activation effect better, preferably, the mass ratio of titanium white waste to concentrated sulfuric acid in S1 is 1:(1-2).

[0023] In the specific embodiment, in order to achieve a better leaching effect, preferably, the mixing solid-liquid ratio of roasted and activated slag to dilute sulfuric acid in S2 is 1:(2-3).

[0024] In the specific embodiment, the dilute sulfuric acid of the present invention can be dilute sulfuric acid with a mass concentration of 15%-25%.

[0025] In the specific embodiment, preferably, the Ti / Al molar ratio of the reaction mother liquor in S2 is (0.4-0.6):1.

[0026] In the specific embodiment, preferably, the mass content of Al2O3 in the aluminum-containing sludge in S2 is 15%-20%.

[0027] In the specific embodiment, preferably, the polymerization and ripening reaction temperature in S3 is 85-95°C.

[0028] In the specific embodiment, the preparation method of the poly-titanium composite coagulant of the present invention can preferentially recover the titanium resources in the titanium white waste residue. Preferably, the titanium content of the titanium white waste residue in S1 is 10%-15% in terms of TiO2, and it also has a high recovery effect for titanium white waste residue with low titanium content.

[0029] The present invention also specifically protects a poly-titanium composite coagulant prepared by the preparation method of the poly-titanium composite coagulant.

[0030] In the specific embodiments, preferably, the molar ratio of n(Ti) / n(Al+Fe+Ca) of the poly-titanium composite coagulant is (0.2-0.4):1, the alumina (Al2O3) ≥ 8.0 wt%, and the basicity is 20-40 wt%.

[0031] The method for preparing the poly-titanium composite coagulant by using titanium white waste residue of the present invention maximizes the utilization rate of titanium resources in the titanium white waste residue, synthesizes a new type of inorganic composite polymer coagulant, improves the flocculation performance of traditional inorganic flocculants, has good stability, strong adsorption and bridging ability for colloidal particles, good coagulation effect, wide application range, and the effluent pH is close to neutral, which is convenient for subsequent treatment and other advantages.

[0032] The present invention also specifically protects the application of a poly-titanium composite coagulant in water treatment.

[0033] The poly-titanium composite coagulant of the present invention can be used for the treatment of various wastewaters, such as papermaking, textile, and printing and dyeing wastewaters, has good flocculation effects, and can significantly reduce the COD value and turbidity before and after water treatment.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] The preparation method of the poly-titanium composite coagulant of the present invention uses titanium white waste residue as the raw material, and fully recovers the TiO2 resources in the titanium white waste residue by using the "calcination activation + acid leaching" process. At the same time, aluminum, iron, and calcium elements are introduced for synergistic enhancement, and the turbidity removal and decolorization effects are good, and more excellent coagulation effects are shown in the treatment of papermaking, textile, and printing and dyeing wastewaters. Specific embodiments

[0036] The following further illustrates the present invention in combination with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw material reagents used in the embodiments of the present invention are conventional raw material reagents purchased.

[0037] The effective component contents of the titanium white waste residue and aluminum-containing sludge used in the examples and comparative examples of the present invention are as follows:

[0038] The titanium content of the titanium white waste residue is 14.6% (calculated as TiO2);

[0039] The aluminum content of the aluminum-containing sludge is 18.9% (calculated as Al2O3).

[0040] Example 1

[0041] A method for preparing a poly-titanium composite coagulant by using titanium white waste residue, comprising the following steps:

[0042] S1. Roasting activation: After drying, grinding, and screening the titanium white waste residue through 80 mesh, concentrated sulfuric acid is added in a mass ratio of 1:2, fully mixed and stirred evenly, then placed in a muffle furnace and roasted and activated at 280 °C for 2 h. After cooling, it is ground to obtain the roasted and activated slag;

[0043] S2. Acid leaching: Mix the roasted and activated slag in S1 with 20% dilute sulfuric acid in a ratio of 1:3, keep it warm and stir in a water bath at 75 °C for 1 - 2 h, then add aluminum-containing sludge and continue to keep it warm and stir in the water bath for 1 h. After the reaction is complete, solid-liquid separation is carried out to obtain a reaction mother liquor with a Ti / Al molar ratio of 0.45:1;

[0044] S3. Polymerization and ripening: Add 3% calcium aluminate powder to the reaction mother liquor in S2 to adjust the solution basicity, keep it warm and stir in a water bath at 90 °C for 2 h and then take it out, ripen at room temperature for 9 h, and carry out solid-liquid separation to obtain the poly-titanium composite coagulant.

[0045] Example 2

[0046] A method for preparing a poly-titanium composite coagulant using titanium white waste residue, comprising the following steps:

[0047] S1. Roasting activation: After drying, grinding, and screening the titanium white waste residue through 80 mesh, concentrated sulfuric acid is added in a mass ratio of 1:2, fully mixed and stirred evenly, then placed in a muffle furnace and roasted and activated at 280 °C for 2 h. After cooling, it is ground to obtain the roasted and activated slag;

[0048] S2. Acid leaching: Mix the roasted and activated slag in S1 with 20% dilute sulfuric acid in a ratio of 1:3, keep it warm and stir in a water bath at 75 °C for 1 - 2 h, then add aluminum-containing sludge and continue to keep it warm and stir in the water bath for 1 h. After the reaction is complete, solid-liquid separation is carried out to obtain a reaction mother liquor with a Ti / Al molar ratio of 0.6:1;

[0049] S3. Polymerization and ripening: Add 3% calcium aluminate powder to the reaction mother liquor in S2 to adjust the solution basicity, keep it warm and stir in a water bath at 90 °C for 2 h and then take it out, ripen at room temperature for 9 h, and carry out solid-liquid separation to obtain the poly-titanium composite coagulant.

[0050] Example 3

[0051] A method for preparing a poly-titanium composite coagulant using titanium white waste residue, comprising the following steps:

[0052] S1. Roasting activation: After drying, grinding, and screening the titanium white waste residue through 80 mesh, concentrated sulfuric acid is added in a mass ratio of 1:2, fully mixed and stirred evenly, then placed in a muffle furnace and roasted and activated at 280 °C for 2 h. After cooling, it is ground to obtain the roasted and activated slag;

[0053] S2. Acid leaching: Mix the roasted and activated slag in S1 with 20% dilute sulfuric acid at a ratio of 1:3, keep it warm and stir in a water bath at 75°C for 1 - 2 h, then add aluminum-containing sludge and continue to stir in the water bath for 1 h. After the reaction is complete, separate the solid and liquid to obtain a reaction mother liquor with a Ti / Al molar ratio of 0.3:1.

[0054] S3. Polymerization and ripening: Add 3% calcium aluminate powder to the reaction mother liquor in S2 to adjust the solution basicity, keep it warm and stir in a water bath at 90°C for 2 h, then take it out and ripen at room temperature for 9 h, and separate the solid and liquid to obtain the poly-titanium composite coagulant.

[0055] Example 4

[0056] A method for preparing a poly-titanium composite coagulant using titanium white waste residue includes the following steps:

[0057] S1. Roasting and activation: After drying, grinding, and screening the titanium white waste residue through 80-mesh sieve, add concentrated sulfuric acid at a mass ratio of 1:2, mix and stir well, place it in a muffle furnace and roast and activate at 280°C for 2 h, then grind after cooling to obtain the roasted and activated slag.

[0058] S2. Acid leaching: Mix the roasted and activated slag in S1 with 20% dilute sulfuric acid at a ratio of 1:3, keep it warm and stir in a water bath at 75°C for 1 - 2 h, then add aluminum-containing sludge and continue to stir in the water bath for 1 h. After the reaction is complete, separate the solid and liquid to obtain a reaction mother liquor with a Ti / Al molar ratio of 0.45:1.

[0059] S3. Polymerization and ripening: Add 3% calcium aluminate powder to the reaction mother liquor in S2 to adjust the solution basicity, keep it warm and stir in a water bath at 80°C for 2 h, then take it out and ripen at room temperature for 9 h, and separate the solid and liquid to obtain the poly-titanium composite coagulant.

[0060] Comparative Example 1

[0061] A method for preparing a poly-titanium composite coagulant using titanium white waste residue includes the following steps:

[0062] S1. Roasting and activation: After drying, grinding, and screening the titanium white waste residue through 80-mesh sieve, add concentrated sulfuric acid at a mass ratio of 1:2, mix and stir well, place it in a muffle furnace and roast and activate at 280°C for 2 h, then grind after cooling to obtain the roasted and activated slag.

[0063] S2. Acid leaching: Mix the roasted and activated slag in S1 with 20% dilute sulfuric acid at a ratio of 1:3, keep it warm and stir in a water bath at 75°C for 1 - 2 h, then add aluminum-containing sludge and continue to stir in the water bath for 1 h. After the reaction is complete, separate the solid and liquid to obtain a reaction mother liquor with a Ti / Al molar ratio of 0.45:1.

[0064] S3. Aggregation and aging: Add 6% calcium aluminate powder to the reaction mother liquor of S2 to adjust the solution basicity, keep it in a water bath at 90 °C with stirring for 2 h and then take it out, age at room temperature for 9 h, and perform solid-liquid separation to obtain the poly-titanium composite coagulant.

[0065] Comparative Example 2

[0066] A method for preparing a poly-titanium composite coagulant using titanium white waste residue, comprising the following steps:

[0067] S1. Acid dissolution and leaching: Dry, grind, and sieve the titanium white waste residue through a 80-mesh sieve, then mix it with 20% dilute sulfuric acid at a ratio of 1:3, keep it in a water bath at 75 °C with stirring for 1 - 2 h, add aluminum-containing sludge, continue to stir in the water bath for 1 h, and perform solid-liquid separation after the reaction is complete to obtain a reaction mother liquor with a Ti / Al molar ratio of 0.45:1;

[0068] S2. Aggregation and aging: Add 3% calcium aluminate powder to the reaction mother liquor of S2 to adjust the solution basicity, keep it in a water bath at 90 °C with stirring for 2 h and then take it out, age at room temperature for 9 h, and perform solid-liquid separation to obtain the poly-titanium composite coagulant.

[0069] Result detection

[0070] (1) Evaluation of product performance indicators

[0071] Comprehensively evaluate the effective indicators of the poly-titanium composite coagulants prepared in the above examples and comparative examples. The evaluation criteria and detection methods refer to "HG / T 5006-2016 Water treatment agent - Poly aluminum sulfate". The specific detection results are shown in Table 2:

[0072] Table 2 Main performance indicators of the poly-titanium composite coagulant product

[0073] Serial number n(Ti) / n(Al + Fe + Ca) <![CDATA[Al2O3 / %]]> Basicity / % Standard requirement 0.2～0.4 ≥8.0 20～40 Example 1 0.30 8.5 30.7 Example 2 0.38 8.3 31.1 Example 3 0.18 8.4 27.6 Example 4 0.31 7.8 19.1 Comparative example 1 0.14 10.3 50.7 Comparative example 2 0.10 8.5 30.3

[0074] (2) Evaluation of the coagulation effect on papermaking wastewater

[0075] Take the papermaking wastewater generated by a certain paper mill as the simulated treated sewage, and its water quality is shown in Table 3. Using the method of controlling variables, under the same test conditions (i.e., controlling variables such as the main performance indicators of the agent, coagulant dosage, coagulation time, stirring speed, etc.), compare and explore the coagulation effect of the poly-titanium composite coagulants prepared in the examples and comparative examples. The results are shown in Table 4.

[0076] Among them, the detection method of COD refers to:

[0077] HJ / T 399-2007 Water quality - Determination of chemical oxygen demand - Fast digestion spectrophotometric method.

[0078] The detection method of turbidity refers to:

[0079] GB / T 13200-1991 Water Quality - Determination of Turbidity - Visual Turbidimetry

[0080] Table 3 Water Quality Indexes of Papermaking Wastewater

[0081] Water quality index Appearance <![CDATA[COD (mg·L -1 )]]> Turbidity / NTU Papermaking wastewater Greyish-black and turbid 3402.15 1600

[0082] Table 4 Coagulation Effects of Wastewater in Examples and Comparative Examples (Dosage of Chemical Reagent is 1.0‰)

[0083]

[0084]

[0085] As can be seen from Table 2 above, all the main performance indexes of the poly - titanium composite coagulant prepared from titanium white waste residue by the present invention can basically meet the standard requirements of the poly - titanium composite coagulant product. As can be seen from Table 4, when the poly - titanium composite coagulant prepared from titanium white waste residue of the present invention is applied to treat papermaking wastewater, it has good coagulation effect on wastewater. The removal rate of COD can reach 81 - 90%, and the removal rate of turbidity is between 84 - 93%. Among them, the polymerization and ripening temperature in Example 4 is slightly on the low side, which will lead to slightly insufficient aluminum content and basicity of the product, and has little overall impact on the molar ratio of n(Ti) / n(Al + Fe + Ca), so the flocculation effect is only slightly lower overall.

[0086] Among them, in Comparative Example 1, the addition amount of calcium aluminate powder exceeds the scope protected by the claims. The excessive addition amount of calcium aluminate powder will lead to a high basicity of the product. The product with high basicity has poor stability, and metal ions are prone to hydrolysis and precipitation, which affects the product quality. Moreover, the molar ratio of n(Ti) / n(Al + Fe + Ca) is not within the protected range. For the flocculation effect, the influence of the molar ratio of n(Ti) / n(Al + Fe + Ca) is the most significant. Therefore, in Table 4, the removal rates of COD and turbidity in Comparative Example 1 are lower than those in the examples.

[0087] Obviously, the above - mentioned examples of the present invention are only examples for clearly explaining the present invention, rather than limitations on the implementation modes of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation modes here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A preparation method of a poly-titanium composite coagulant, characterized in that, The steps include: S1. Calcination activation: The titanium dioxide waste residue is fully mixed with concentrated sulfuric acid, placed at 250-300 ° C for calcination activation for 2-3h, and cooled to obtain the calcined activated slag; S2. Acid leaching: Mix the roasted activated slag in S1 with dilute sulfuric acid, react at 70-80°C for 1-2h, then add aluminum-containing sludge, keep warm for 0.5-1h, separate the solid and liquid after the reaction is complete, and obtain the reaction mother liquor; S3 polymerization aging: Add calcium aluminate powder to the reaction mother liquor S2, and react at 80 to 95 ° C for 1 to 2h, remove, mature at room temperature, and separate the solid and liquid to obtain a poly-titanium composite coagulant with a basicity of 20 to 40wt%. The amount of calcium aluminate powder added to S3 is 2-4% of the mass of the reaction mother liquor.

2. The preparation method of the poly-titanium composite coagulant according to claim 1, characterized in that The mass ratio of titanium dioxide waste slag to concentrated sulfuric acid in S1 is 1:(1-2).

3. The preparation method of the poly-titanium composite coagulant according to claim 1, characterized in that, The mixed solid-liquid ratio of the roasted activated slag and the dilute sulfuric acid in S2 is 1:(2-3).

4. The preparation method of the poly-titanium composite coagulant according to claim 1, characterized in that, The Ti / Al molar ratio of the reaction mother liquor in S2 is (0.4-0.6):

1.

5. The preparation method of the poly-titanium composite coagulant according to claim 4, characterized in that, The mass content of Al2O3 in the aluminum-containing sludge in S2 is 15% to 20%.

6. The preparation method of the poly-titanium composite coagulant according to claim 1, characterized in that, The polymerization aging reaction temperature in S3 is 85-95°C.

7. The preparation method of the poly-titanium composite coagulant according to any one of claims 1 to 6, characterized in that The titanium content of the titanium dioxide waste slag in S1 is 10-15%, calculated as TiO2.

8. A poly-titanium composite coagulant prepared by the method for preparing the poly-titanium composite coagulant according to any one of claims 1 to 7.

9. The poly-titanium composite coagulant according to claim 8, wherein The polytitanium composite coagulant has a molar ratio of n(Ti) / n(Al+Fe+Ca) of (0.2-0.4):1, an aluminum oxide content of ≥8.0wt%, and a basicity of 20-40wt%.

10. Use of the polytitanium composite coagulant according to claim 8 or 9 in water treatment.

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