A method for treating thallium in raffinate wastewater

Abstract

The application provides a treatment method of thallium in raffinate wastewater, and belongs to the technical field of wastewater treatment. In the treatment method of thallium in raffinate wastewater, a Fenton-like catalytic oxidation system is formed by using an oxidizing agent and an iron compound, the raffinate wastewater is subjected to leaching and catalytic oxidation, then the pH of the obtained first solution is adjusted, finally a high-molecular flocculating agent is added for precipitation to obtain purified water. The treatment method of thallium in raffinate wastewater can not only effectively remove thallium with low mass concentration in the raffinate wastewater, but also effectively remove heavy metals other than thallium with high mass concentration in the raffinate wastewater.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, specifically to a method for treating thallium in extraction wastewater. Background Technology

[0002] Thallium (Tl) is a highly toxic heavy metal, far exceeding the toxicity of common heavy metals such as arsenic (As) and cadmium (Cd). Even trace amounts of thallium can enter the human body through the food chain or skin contact, leading to neurological damage, organ failure, and even death. In recent years, in-situ leaching processes have been widely used in the mining of ion-adsorption rare earth minerals. However, the magnesium oxide enrichment and purification process in this process generates leaching wastewater containing high concentrations of heavy metals such as nickel, lead, cadmium, thorium, and uranium, as well as trace amounts of thallium.

[0003] Currently, the main methods for treating thallium-containing wastewater include chemical precipitation, ion exchange, and adsorption. While chemical precipitation is simple to operate, it generates a large amount of sludge, and the treated water quality often fails to meet stringent discharge standards. Ion exchange requires specific operating conditions, and the resin regeneration process is complex and costly. Adsorption, due to its high efficiency, ease of operation, and relatively low cost, is widely used in thallium-containing wastewater treatment. However, existing adsorbents still have many problems in practical applications. Catalytic oxidation, while a simple separation method, is relatively expensive. my country has extremely strict discharge standards for thallium-containing wastewater (≤5 μg / L). For raffinate wastewater, due to the influence of other heavy metals and the low thallium content, catalytic oxidation treatment still faces challenges such as susceptibility to interference from other ions and long treatment times, making it difficult to remove thallium from the raffinate wastewater, and the treated water quality often fails to meet the discharge standards for thallium-containing wastewater. Summary of the Invention

[0004] The purpose of this application is to overcome the shortcomings of the prior art and provide a method for treating thallium in extraction wastewater.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows: a method for treating thallium in extraction wastewater is provided, comprising the following steps: S1: The addition of the oxidant is divided into two stages: a first oxidant and a second oxidant. The first oxidant is added to the raffinate wastewater and stirred for the first time. Then, an iron-based compound is added and stirred for the second time. Finally, the second oxidant is added and stirred for the third time to obtain the first solution. The pH of the raffinate wastewater is ≤4 or ≥9.5. S2: When the pH of the raffinate wastewater is ≤4, add an inorganic alkali to the first solution to make the pH of the first solution ≥9; then add a polymeric flocculant, stir evenly, let stand, and separate the solid and liquid to obtain purified water; When the pH of the residual wastewater is ≥9.5, a polymeric flocculant is added to the first solution, stirred evenly, allowed to stand, and the solid and liquid are separated to obtain purified water. Based on the mass of thallium-containing wastewater, the oxidant has a mass percentage of 0.5-1%, the iron-based compound has a mass percentage of 0.2-0.32%, and the polymeric flocculant has a mass percentage of 0.001-0.005%; the oxidant is hydrogen peroxide, and the iron-based compound includes at least one of polyferric sulfate and polyferric chloride.

[0006] In some embodiments, the mass percentage of the first oxidant is 50-70% based on the mass of the oxidant.

[0007] In some embodiments, the polymeric flocculant includes at least one of polyaluminum chloride and polyacrylamide.

[0008] In some embodiments, the polymeric flocculant is polyaluminum chloride and polyacrylamide; based on the total mass of polyaluminum chloride and polyacrylamide, the mass percentage of polyaluminum chloride is 50-80%.

[0009] In some embodiments, the inorganic base includes at least one of alkali metal oxides and hydroxides.

[0010] In some embodiments, the duration of the first stirring, the second stirring, and the third stirring is independently 4 to 6 minutes.

[0011] In some embodiments, the rotation speeds of the first, second, and third stirring are 200 to 400 rpm.

[0012] In some embodiments, the settling time is 1 to 5 minutes.

[0013] Compared with the prior art, the beneficial effects of this application are as follows: In the method for treating thallium in the leaching wastewater of this application, the oxidant and iron-based compounds form a Fenton-like catalytic oxidation system, with the iron-based compounds serving as the iron source catalyst, and the oxidant in Fe... 3+ with Fe 2+ Under the catalytic action of recycling, •OH radicals can be efficiently generated. These •OH radicals can catalyze the formation of soluble monovalent thallium (Tl) in the leaching wastewater. + ) is converted into trivalent thallium (Tl) which is easily hydrolyzed and precipitated. 3+ Iron-based compounds hydrolyze to produce large amounts of polynuclear hydroxyl complexes (such as [Fe3(OH)4)). 5+The high positive charge and large molecular weight of polynuclear hydroxyl complexes, including Fe(OH)3 colloids, give them a strong charge neutralization ability. They can efficiently neutralize the negative charge of Tl(OH)3 colloids generated under oxidation and alkaline conditions, thus destabilizing the Tl(OH)3 colloids. During the formation of Fe(OH)3 colloids, they can act as a carrier, trapping and sweeping tiny Tl(OH)3 and other heavy metal hydroxide precipitates to form flocs. Through the charge neutralization effect of the polymeric flocculant, they combine with the flocs to form fine and sparse flocculent particles (hereinafter referred to as micro-flocs). That is, through the "adsorption bridging" and "trapping and sweeping" effects of the long molecular chains in the polymeric flocculant, the flocs aggregate to form large and dense flocculent particles that can settle quickly, thereby removing heavy metals (including nickel, lead, cadmium, thorium, uranium, and thallium) from the leaching wastewater. Adding the oxidant in stages before and after the addition of iron-based compounds can avoid ineffective decomposition and free radical quenching of the oxidant, thereby improving the removal efficiency of heavy metals in the raffinate wastewater. If the oxidant is added all at once before or after the addition of iron-based compounds, sufficient oxidation cannot be achieved, and the iron-based compounds may be over-oxidized or incompletely catalyzed, reducing the removal efficiency of heavy metals in the raffinate wastewater. Attached Figure Description

[0014] Figure 1 A schematic diagram of a process for treating thallium in extraction wastewater; Figure 2 The graph shows the mass concentration of Tl in the purified water obtained in Examples 2-3 and Comparative Examples 1-5. Figure 3 The graph shows the mass concentration of Tl in the purified water obtained in Examples 4-5 and Comparative Examples 6-10. Figure 4 The diagram shows the mass concentration of Tl in the purified water obtained in Examples 6-8 and Comparative Examples 11-16. Figure 5 The diagram shows the mass concentration of Tl in the purified water obtained in Examples 9-10 and Comparative Examples 17-21. Figure 6 The graph shows the removal rates of different heavy metals in Examples 2-3 and Comparative Examples 1-5. Figure 7 The graph shows the removal rates of different heavy metals in Examples 2-5 and Comparative Examples 6-10. Figure 8 The removal rates of different heavy metals in Examples 6-8 and Comparative Examples 11-16 are shown in the graph. Figure 9 The graph shows the removal rates of different heavy metals in Examples 9-10 and Comparative Examples 17-21. Figure 10 The graph shows the mass concentration of different heavy metals in the purified water obtained in Example 1 and Comparative Example 26. Figure 11The graph shows the mass concentrations of different heavy metals in the purified water obtained in Example 1 and Comparative Example 27. Figure 12 The images show the effects of different standing times in step S2 of Example 1 and Comparative Example 28. Detailed Implementation

[0015] To facilitate understanding of this application, a more complete description will be provided below. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0016] As used in this article: "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0017] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0018] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1-5” is disclosed, the described range should be interpreted as including ranges “1-4”, “1-3”, “1-2”, “1-2 and 4-5”, “1-3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0019] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0020] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has 'a' parts by mass and component B has 'b' parts by mass, it means that the mass ratio of component A to component B is a:b. It is important to understand that, unlike mass percentage content, the sum of the mass parts of all components is not limited to 100 parts.

[0021] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0022] This application provides a method for treating thallium in extraction wastewater, including the following steps: S1: The addition of the oxidant is divided into two stages: a first oxidant and a second oxidant. The first oxidant is added to the raffinate wastewater and stirred for the first time. Then, an iron-based compound is added and stirred for the second time. Finally, the second oxidant is added and stirred for the third time to obtain the first solution. The pH of the raffinate wastewater is ≤4 or ≥9.5. S2: As Figure 1 As shown, when the pH of the raffinate wastewater is ≤4, an inorganic alkali is added to the first solution to make the pH of the first solution ≥9; then a polymeric flocculant is added, stirred evenly, allowed to stand, and the solid and liquid are separated to obtain purified water. When the pH of the residual wastewater is ≥9.5, a polymeric flocculant is added to the first solution, stirred evenly, allowed to stand, and the solid and liquid are separated to obtain purified water. Based on the mass of the raffinate wastewater, the oxidant has a mass percentage of 0.5-1%, the iron-based compound has a mass percentage of 0.2-0.32%, and the polymeric flocculant has a mass percentage of 0.001-0.005%; the oxidant is hydrogen peroxide, and the iron-based compound includes at least one of polyferric sulfate and polyferric chloride.

[0023] In the method for treating thallium in the residue wastewater of this application, the oxidant and iron-based compounds form a Fenton-like catalytic oxidation system, with the iron-based compounds serving as the iron source catalyst. The oxidant reacts with Fe... 3+ with Fe 2+ Under the catalytic action of recycling, •OH radicals can be efficiently generated. These •OH radicals can catalyze the formation of soluble monovalent thallium (Tl) in the leaching wastewater. + ) is converted into trivalent thallium (Tl) which is easily hydrolyzed and precipitated. 3+ Iron-based compounds hydrolyze to produce large amounts of polynuclear hydroxyl complexes (such as [Fe3(OH)4)). 5+The high positive charge and large molecular weight of polynuclear hydroxyl complexes, including Fe(OH)3 colloids, give them a strong charge neutralization ability. They can efficiently neutralize the negative charge of Tl(OH)3 colloids generated under oxidation and alkaline conditions, thus destabilizing the Tl(OH)3 colloids. During the formation of Fe(OH)3 colloids, they can act as a carrier, trapping and sweeping tiny Tl(OH)3 and other heavy metal hydroxide precipitates to form flocs. Through the charge neutralization effect of the polymeric flocculant, they combine with the flocs to form fine and sparse flocculent particles (hereinafter referred to as micro-flocs). That is, through the "adsorption bridging" and "trapping and sweeping" effects of the long molecular chains in the polymeric flocculant, the flocs aggregate to form large and dense flocculent particles that can settle quickly, thereby removing heavy metals (including nickel, lead, cadmium, thorium, uranium, and thallium) from the leaching wastewater. Adding the oxidant in stages before and after the addition of iron-based compounds can avoid ineffective decomposition and free radical quenching of the oxidant, thereby improving the removal efficiency of heavy metals in the raffinate wastewater. If the oxidant is added all at once before or after the addition of iron-based compounds, sufficient oxidation cannot be achieved, and the iron-based compounds may be over-oxidized or incompletely catalyzed, reducing the removal efficiency of heavy metals in the raffinate wastewater.

[0024] In this application, the low mass percentage of oxidant and iron-based compounds will lead to a significant decrease in the removal efficiency of heavy metals in the raffinate wastewater, especially thallium.

[0025] Specifically, based on the mass of the raffinate wastewater, the mass percentage of the oxidant can be a range of one or any combination of 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, and 1%.

[0026] Specifically, based on the mass of the leaching wastewater, the mass percentage of polyferric sulfate can be a range of one or any combination of 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, 0.3%, and 0.32%.

[0027] Specifically, based on the mass of the leaching wastewater, the mass percentage of the polymeric flocculant can be a range of one or any two of the following: 0.001%, 0.002%, 0.003%, 0.004%, and 0.005%.

[0028] In some embodiments, the mass percentage of the first oxidant is 50-70% based on the mass of the oxidant; for example, it can be a range of one or any two of 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, and 70%.

[0029] In this application, the mass percentage of the first oxidant is within the above-mentioned range, which is beneficial to improving the removal efficiency of thallium in the raffinate wastewater.

[0030] In some embodiments, the polymeric flocculant includes at least one of polyaluminum chloride and polyacrylamide.

[0031] In some embodiments, the polymeric flocculant is polyaluminum chloride and polyacrylamide; based on the total mass of polyaluminum chloride and polyacrylamide, the mass percentage of polyaluminum chloride is 50-80%; for example, it can be a range of one or any two of 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%.

[0032] In this application, the mass percentage of polyaluminum chloride is within the above-mentioned range, which is beneficial to improving the removal efficiency of thallium in the raffinate wastewater.

[0033] In some embodiments, the inorganic base includes at least one of alkali metal oxides and hydroxides.

[0034] In some embodiments, the times for the first stirring, the second stirring, and the third stirring are each independently 4 to 6 minutes; for example, they can be a range of one or any two of 4 minutes, 4.5 minutes, 5 minutes, 5.5 minutes, and 6 minutes.

[0035] In some embodiments, the rotation speed of the first, second, and third stirring is 200 to 400 rpm; for example, it can be a range of one or any two of 200 rpm, 220 rpm, 240 rpm, 260 rpm, 280 rpm, 300 rpm, 320 rpm, 340 rpm, 360 rpm, 380 rpm, and 400 rpm.

[0036] In some embodiments, the settling time is 1 to 5 minutes; for example, it can be a range of one or any two of 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, and 5 minutes.

[0037] In this application, the stirring and settling times in steps S1 and S2 are short, which can effectively shorten the treatment time of the leaching wastewater and greatly improve the treatment efficiency of the leaching wastewater.

[0038] Example 1 This embodiment provides a method for treating thallium in extraction wastewater, including the following steps: S1: The addition of oxidant is divided into two stages: first oxidant and second oxidant. First oxidant is added to the raffinate wastewater and stirred at 300 rpm for 5 min. Then iron-based compounds are added and stirred at 300 rpm for 5 min. Then second oxidant is added and stirred at 300 rpm for 5 min to obtain the first solution. The residue wastewater was analyzed by inductively coupled plasma mass spectrometry (PerkinElmer NexION 2200G) (HJ700-2014), and the contents of each heavy metal were as follows: [Tl]=20.8μg / L, [Ni]=2.7564 mg / L, [Cd]=1.9210 mg / L, [Pb]=0.1092 mg / L, [Th]=0.0845 mg / L, [U]=12741mg / L; The pH of the leaching wastewater is 4 (called the initial pH). S2: Add sodium hydroxide to the first solution to make the pH of the first solution = 9 (called the termination pH); then add polymeric flocculant, stir at 300 rpm for 20 min, let stand for 1 min, and separate solid and liquid to obtain purified water; Based on the mass of the leaching wastewater, the mass percentage of oxidant is 0.5%, the mass percentage of iron-based compounds is 0.2%, and the mass percentage of polymeric flocculant is 0.003%. The oxidant is hydrogen peroxide, the iron-based compound is polyferric sulfate, and the polymeric flocculants are polyaluminum chloride and polyacrylamide. Based on the total mass of polyaluminum chloride and polyacrylamide, the mass percentage of polyaluminum chloride is 50%. Based on the mass of the oxidant, the mass percentage of the first oxidant is 50%.

[0039] Examples 2-3 and Comparative Examples 1-5 Examples 2-3 and Comparative Examples 1-5 provide a method for treating thallium in raffinate wastewater. The difference between these methods and Example 1 is that the mass percentage of the oxidant is different; all other aspects are the same as in Example 1.

[0040] In Example 2, based on the mass of the raffinate wastewater, the mass percentage of the oxidant was 0.7%. In Example 3, based on the mass of the raffinate wastewater, the mass percentage of the oxidant was 1%. In Comparative Example 1, based on the mass of the raffinate wastewater, the mass percentage of the oxidant was 0%. In Comparative Example 2, based on the mass of the raffinate wastewater, the mass percentage of the oxidant was 0.1%. In Comparative Example 3, based on the mass of the raffinate wastewater, the mass percentage of the oxidant was 0.2%. In Comparative Example 4, based on the mass of the raffinate wastewater, the mass percentage of the oxidant was 0.3%. In Comparative Example 5, the mass percentage of oxidant was 0.4% based on the mass of the raffinate wastewater.

[0041] Examples 4-5 and Comparative Examples 6-10 Examples 5-6 and Comparative Examples 6-10 provide a method for treating thallium in raffinate wastewater. The difference between these methods and Example 1 is that the mass percentage content of iron compounds is different; otherwise, they are the same as in Example 1.

[0042] In Example 4, based on the mass of the raffinate wastewater, the mass percentage of iron compounds was 0.24%. In Example 5, based on the mass of the raffinate wastewater, the mass percentage of iron compounds was 0.32%. In Comparative Example 6, based on the mass of the raffinate wastewater, the mass percentage of iron compounds was 0%. In Comparative Example 7, based on the mass of the raffinate wastewater, the mass percentage of iron compounds was 0.04%. In Comparative Example 8, based on the mass of the raffinate wastewater, the mass percentage of iron compounds was 0.08%. In Comparative Example 9, based on the mass of the raffinate wastewater, the mass percentage of iron compounds was 0.12%. In Comparative Example 10, the mass percentage of iron compounds was 0.16% based on the mass of the raffinate wastewater.

[0043] Examples 6-8 and Comparative Examples 11-16 Examples 6-8 and Comparative Examples 11-16 provide a method for treating thallium in raffinate wastewater, which differs from Example 1 in that the pH of the first solution is different in step S2.

[0044] In Example 6, the pH of the first solution was 9.5; In Example 7, the pH of the first solution was 9.7; In Example 8, the pH of the first solution was 9.8; In Comparative Example 11, the pH of the first solution was 3; In Comparative Example 12, the pH of the first solution was 4; In Comparative Example 13, the pH of the first solution was 5; In Comparative Example 14, the pH of the first solution was 6; In Comparative Example 15, the pH of the first solution was 7; In Comparative Example 16, the pH of the first solution was 8.

[0045] Examples 9-10 and Comparative Examples 17-21 Examples 11-12 and Comparative Examples 17-21 provide a method for treating thallium in raffinate wastewater, which differs from Example 1 in that the pH of the raffinate wastewater is different.

[0046] In Example 9, the pH of the leaching wastewater was 9.5; In Example 10, the pH of the raffinate wastewater was 9.7; In Comparative Example 17, the pH of the raffinate wastewater was 5; In Comparative Example 18, the pH of the raffinate wastewater was 6; In Comparative Example 19, the pH of the raffinate wastewater was 7; In Comparative Example 20, the pH of the raffinate wastewater was 8; In Comparative Example 21, the pH of the leaching wastewater was 9.

[0047] Example 11 and Comparative Examples 22-25 Example 11 and Comparative Example 25 provide a method for treating thallium in raffinate wastewater. The difference between them and Example 1 is that the mass percentage of the first oxidant is different; the rest are the same as in Example 1.

[0048] In Example 11, based on the mass of the oxidant, the mass percentage of the first oxidant is 70%; In Comparative Example 22, based on the mass of the oxidant, the mass percentage of the first oxidant was 0%; In Comparative Example 23, based on the mass of the oxidant, the mass percentage of the first oxidant was 40%; In Comparative Example 24, based on the mass of the oxidant, the mass percentage of the first oxidant was 80%; In Comparative Example 25, the mass percentage of the first oxidant was 100% based on the mass of the oxidant.

[0049] Comparative Example 26 Comparative Example 26 provides a method for treating thallium in raffinate wastewater. The difference between this method and Example 1 is that the oxidant is different; the oxidant in this comparative example is sodium persulfate.

[0050] Comparative Example 27 Comparative Example 27 provides a method for treating thallium in raffinate wastewater. The difference between this method and Example 1 is that the iron-based compound is different; the iron-based compound in this comparative example is ferrous sulfate.

[0051] Comparative Example 28 Comparative Example 28 provides a method for treating thallium in leaching wastewater. The difference between this method and Example 1 is that the content of polymeric flocculant is different; no polymeric flocculant was added in this comparative example.

[0052] Content testing The purified water obtained in step S2 of the examples and comparative examples was analyzed by inductively coupled plasma mass spectrometry (PerkinElmer NexION 2200G) (HJ 700-2014). The test results are shown in Table 1 and... Figures 2-11 As shown.

[0053] Table 1 As can be seen from the experimental data in Table 1, the method of this application can effectively remove heavy metals from the extraction wastewater.

[0054] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of this application and not to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. A method for treating thallium in extraction wastewater, characterized in that, Includes the following steps: S1: The addition of the oxidant is divided into two stages: a first oxidant and a second oxidant. The first oxidant is added to the raffinate wastewater and stirred for the first time. Then, an iron-based compound is added and stirred for the second time. Finally, the second oxidant is added and stirred for the third time to obtain the first solution. The pH of the raffinate wastewater is ≤4 or ≥9.

5. S2: When the pH of the raffinate wastewater is ≤4, add an inorganic alkali to the first solution to make the pH of the first solution ≥9; then add a polymeric flocculant, stir evenly, let stand, and separate the solid and liquid to obtain purified water; When the pH of the residual wastewater is ≥9.5, a polymeric flocculant is added to the first solution, stirred evenly, allowed to stand, and the solid and liquid are separated to obtain purified water. Based on the mass of the raffinate wastewater, the oxidant has a mass percentage of 0.5-1%, the iron-based compound has a mass percentage of 0.2-0.32%, and the polymeric flocculant has a mass percentage of 0.001-0.005%; the oxidant is hydrogen peroxide, and the iron-based compound includes at least one of polyferric sulfate and polyferric chloride.

2. The method for treating thallium in extraction wastewater as described in claim 1, characterized in that, Based on the mass of the oxidant, the mass percentage of the first oxidant is 50-70%.

3. The method for treating thallium in extraction wastewater as described in claim 1, characterized in that, The polymeric flocculant includes at least one of polyaluminum chloride and polyacrylamide.

4. The method for treating thallium in extraction wastewater as described in claim 3, characterized in that, The polymeric flocculant includes polyaluminum chloride and polyacrylamide; based on the total mass of polyaluminum chloride and polyacrylamide, the mass percentage of polyaluminum chloride is 50-80%.

5. The method for treating thallium in extraction wastewater as described in claim 1, characterized in that, The inorganic base includes at least one of alkali metal oxides and hydroxides.

6. The method for treating thallium in extraction wastewater as described in claim 1, characterized in that, The stirring times for the first, second, and third stirring are each 4 to 6 minutes.

7. The method for treating thallium in extraction wastewater as described in claim 1, characterized in that, The rotation speeds of the first, second, and third stirring operations are 200-400 rpm.

8. The method for treating thallium in extraction wastewater as described in claim 1, characterized in that, The settling time is 1 to 5 minutes.

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