A method for treating waste residue containing thallium

Abstract

The present invention provides a method for treating thallium-containing waste residue, comprising the steps of: S1, providing synthetic sulfur produced within 10 days of its synthesis date; wherein the synthetic sulfur is synthesized by mixing sulfite and sulfide in an acidic solution to obtain the synthetic sulfur; and S2, subjecting the thallium-containing waste residue, the synthetic sulfur, and water to a hydrothermal reaction to obtain a treatment solution and solidified thallium treatment residue; wherein the temperature of the hydrothermal reaction is 180 to 240°C. The present invention can achieve stable solidification of thallium and reduce the risk of thallium leaching from the waste residue.

Description

Technical Field

[0001] The invention relates to the treatment of solid waste from nonferrous metal smelting, and in particular to a method for treating thallium-containing waste residue. Background Art

[0002] Thallium (Tl) is a typical toxic heavy metal with cumulative properties. It is recognized worldwide as one of the 13 metal pollutants with priority control. Thallium primarily causes toxic effects on the human nervous system, with a minimum lethal dose of 10-15 mg / kg. Thallium and its compounds are also mutagenic and carcinogenic. Its toxic effects on the human body are far more potent than those of heavy metals such as lead, cadmium, and mercury, and are similar in toxicity to arsenic. Thallium is found in nature in galena and sphalerite. During ore mining and smelting, it is gradually released into waste residues, wastewater, and exhaust gases.

[0003] Waste slag (dust) generated during the smelting process, such as copper slag, cobalt-nickel slag, lead slag, cadmium slag acid leaching slag, high-fluorine and chlorine fly ash, etc., all contain thallium, which has the characteristics of wide distribution, high content and strong toxicity.

[0004] In view of this, it is necessary to provide a method for treating thallium-containing waste slag to solve or alleviate the technical defect that thallium in the thallium-containing waste slag is easily released. Summary of the Invention

[0005] The main purpose of the present invention is to provide a method for treating thallium-containing waste residue, aiming to solve the technical problem that thallium in the thallium-containing waste residue is easily released.

[0006] To achieve the above object, the present invention provides a method for treating thallium-containing waste residue, comprising the steps of:

[0007] S1, providing synthetic sulfur within 10 days of the synthesis date;

[0008] The synthetic sulfur synthesis process includes: mixing sulfite and sulfide in an acidic solution to obtain the synthetic sulfur;

[0009] S2, subjecting the thallium-containing waste residue, the synthetic sulfur, and water to a hydrothermal reaction to obtain a treatment liquid and solid thallium treatment residue;

[0010] Wherein, the temperature of the hydrothermal reaction is 180-240°C.

[0011] Furthermore, the sulfite includes sodium sulfite; the sulfide salt includes sodium sulfide nonahydrate; and the acidic solution includes sulfuric acid solution.

[0012] Furthermore, in step S1, the molar ratio of the sulfite to the sulfide salt is 1:1.5-3.5, and the concentration of the acidic solution is 0.2-0.4 mol / L.

[0013] Furthermore, the mixing temperature in step S1 is 15-35°C.

[0014] Furthermore, the mixing time in step S1 is 2 to 24 hours.

[0015] Furthermore, in step S2, the mass ratio of the thallium-containing waste residue to the synthetic sulfur is 1:0.5-1; the sum of the masses of the thallium-containing waste residue and the synthetic sulfur: the volume of the water is 1-2 g:1 mL.

[0016] Furthermore, the hydrothermal reaction lasts for 12 to 24 hours.

[0017] Furthermore, the thallium-containing waste residue also contains one or more of cadmium, copper and lead.

[0018] Furthermore, the thallium-containing waste slag includes one or more of copper slag, cobalt-nickel slag, lead slag, cadmium slag acid leaching slag and high-fluorine and chlorine fly ash generated during the smelting process.

[0019] Furthermore, the step S2 further comprises: before carrying out the hydrothermal reaction, mixing the thallium-containing waste residue, the synthetic sulfur, and the water.

[0020] Compared with the prior art, the present invention has at least the following advantages:

[0021] The present invention can achieve the solidification of thallium, thereby inhibiting the leaching and release of thallium from thallium-containing waste residues. Specifically, the present invention synthesizes highly active elemental sulfur. Under conditions above 180°C, the molecular structure of elemental sulfur can effectively transform from the symmetric stretching vibration of the S8 ring molecule to the symmetric stretching vibration of the polymeric sulfur chain, thereby enhancing the binding of sulfur and thallium and achieving stable solidification of thallium in the treated slag after hydrothermal treatment. Moreover, compared with other elemental sulfurs such as sublimated sulfur, the specific elemental sulfur used in the present invention can achieve superior thallium solidification effects at specific temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0023] Figure 1 This is the XRD pattern of sulfur synthesized in Example 1 of the present invention.

[0024] The realization of the objectives, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0026] Moreover, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0027] In order to achieve the solidification of thallium in thallium-containing waste residue and provide those skilled in the art with more options for treating thallium-containing waste residue, the present invention provides a new method for treating thallium-containing waste residue, comprising the steps of:

[0028] S1, providing synthetic sulfur within 10 days from a synthesis date, wherein the synthetic sulfur is elemental sulfur; the synthesis date is the date corresponding to the completion of the synthesis of the synthetic sulfur.

[0029] It should be emphasized that not all elemental sulfur can play the same role in the present application (for example, sublimed sulfur cannot achieve the same role), and not all synthetic sulfur obtained according to the following synthesis process can be used in the present invention.

[0030] After exploration, it was found that only synthetic sulfur within a specific period (within 10 days from the synthesis date) can achieve the technical effect of the present invention.

[0031] In order to ensure the role of the synthetic sulfur in the present invention, the synthetic sulfur can be stored in a sealed state at room temperature within a limited period.

[0032] The synthetic sulfur synthesis process includes: mixing sulfite and sulfide in an acidic solution to obtain the synthetic sulfur; the molar ratio of the sulfite to the sulfide can be 1:1.5-3.5, and the concentration of the acidic solution can be 0.2-0.4 mol / L.

[0033] During the mixing process, the mixing temperature can be maintained at 15 to 35° C., the mixing time can be controlled to be 2 to 24 hours, and the mixing process can be carried out in a closed environment.

[0034] It should be noted that after the mixing process is completed, in order to separate the synthetic sulfur, the liquid after the reaction is usually subjected to solid-liquid separation to obtain a solid product, and the solid product is the synthetic sulfur.

[0035] In the synthetic sulfur synthesis process, the sulfite may include or be sodium sulfite (Na2SO3); the sulfide salt may include or be sodium sulfide nonahydrate (Na2S·9H2O); and the acidic solution may include or be a sulfuric acid solution.

[0036] S2, hydrothermally reacting the thallium-containing waste residue, the synthetic sulfur, and water to obtain a treatment liquid and a solid thallium treatment residue; the mass ratio of the thallium-containing waste residue and the synthetic sulfur can be 1:0.5~1; the sum of the masses of the thallium-containing waste residue and the synthetic sulfur: the volume of the water can be 1~2g:1mL.

[0037] Before the hydrothermal reaction, the thallium-containing waste residue, the synthetic sulfur, and water may be mixed to obtain a solid-liquid mixture thereof, wherein the pH of the solid-liquid mixture is generally 7 to 14. After the hydrothermal reaction, the hydrothermal product may be subjected to solid-liquid separation to separate the treatment liquid and the solid thallium treatment residue.

[0038] At temperatures above 180°C, the molecular structure of elemental sulfur can effectively transform from the symmetric stretching vibration of the S8 ring molecule to the symmetric stretching vibration of the polymeric sulfur chain. This characteristic of elemental sulfur above 180°C can enhance the binding of sulfur and thallium, achieving stable solidification of thallium in the treated slag after hydrothermal treatment. Therefore, the hydrothermal reaction temperature in the present invention can be 180-240°C; preferably, the hydrothermal reaction duration can be 12-24 hours.

[0039] As an illustration of the thallium-containing waste slag described in the present invention, the thallium-containing waste slag contains thallium, and the mass content of thallium is generally not higher than 1.0%. Since the thallium-containing waste slag is usually smelting waste, the thallium-containing waste slag may also contain other heavy metal elements; for example, the thallium-containing waste slag may also contain one or more of cadmium, copper, and lead, wherein the mass content of cadmium is generally not higher than 2.0%, the mass content of copper is generally not higher than 2.0%, and the mass content of lead is generally not higher than 20.0%. Of course, the thallium-containing waste slag may also contain common heavy metal elements such as zinc, chromium, and arsenic.

[0040] Specifically, the thallium-containing waste slag may include or be one or more of copper slag, cobalt-nickel slag, lead slag, cadmium slag acid leaching slag, and high-fluorine and chlorine fly ash generated during the smelting process.

[0041] It should be pointed out that even if the thallium-containing waste residue contains multiple heavy metal elements, the present invention can still solidify thallium and overcome the interference of other heavy metal elements.

[0042] In order to facilitate understanding of the above implementation method, an example is given below:

[0043] In the following examples and comparative examples, leaching toxicity was tested according to the Toxicity Characteristic Leaching Method (TCLP) (US EPA Method 1311).

[0044] Example 1

[0045] Synthetic elemental sulfur:

[0046] 1. Take a 1000mL conical flask;

[0047] 2. Add 500 mL of acidic solution (0.368 mol / L H2SO4) to the conical flask;

[0048] 3. Then, add 12.60g of sodium sulfite (Na2SO3) and 72.0g of sodium sulfide nonahydrate (Na2S·9H2O) to the conical flask respectively;

[0049] 4. The conical flask was placed in a sealed container with an electromagnetic stirrer (500 rpm) at a constant temperature (25° C.) for 2 h. After filtration and separation, elemental sulfur was obtained, which was recorded as synthetic sulfur. The synthetic sulfur was sealed and stored at room temperature (the synthetic sulfur in subsequent examples and comparative examples was derived from this example).

[0050] The XRD pattern of elemental sulfur in this example is shown in Figure 2. Figure 1 As shown, it can be seen that this embodiment completes the synthesis of elemental sulfur.

[0051] Example 2

[0052] The thallium-containing waste residue in this embodiment is: cadmium slag acid leaching residue (in mass percentage, zinc is 37.34%, lead is 18.44%, cadmium is 1.83%, thallium is 0.77%, and copper is 0.18%).

[0053] 7.5 g of thallium-containing waste residue, 7.5 g of synthetic sulfur (5 days from the synthesis date) and 15 ml of pure water were fully mixed to obtain a solid-liquid mixture.

[0054] The solid-liquid mixture was placed in a hydrothermal reactor and sealed. The hydrothermal reactor was set and heated to 180° C., and a hydrothermal reaction was carried out at this temperature for 24 hours. After the reaction was completed, the mixture was allowed to stand and cool to room temperature.

[0055] The hydrothermal reactor was opened, and the supernatant and the precipitate were separated by filtration to obtain a filtrate (processing liquid) and a filter residue (solid thallium processing residue).

[0056] Comparative Example 1

[0057] In this comparative example, compared with Example 2, only the synthetic sulfur was removed, and other conditions remained unchanged. Specifically, 7.5 g of thallium-containing waste residue was mixed with 15 ml of pure water and placed in a hydrothermal reactor.

[0058] Comparative Example 2

[0059] Compared with Example 2, this comparative example only changed the synthetic sulfur to sublimed sulfur (commercially available), and other conditions remained unchanged.

[0060] Analysis example 1

[0061] In Example 2, Comparative Example 1 and Comparative Example 2, the content of each element in the treatment solution (mg / L), and the leaching toxicity of each element in the solid thallium treatment slag (mg / L) are shown in the following table:

[0062]

[0063] It can be seen that the thallium content in the treatment liquid of the synthetic sulfur treatment group (59.4 mg / L) is lower than that of the non-sulfur treatment group (300.9 mg / L) and the sublimated sulfur treatment group (174.01 mg / L).

[0064] The leaching toxicity study of the slag after the hydrothermal reaction found that the thallium leaching toxicity of the slag treated with synthetic sulfur and sublimated sulfur was lower than that of the slag treated without sulfur, achieving stable solidification of thallium in the slag after hydrothermal reaction.

[0065] In summary, the hydrothermal + synthetic sulfur method used in Example 2 can effectively treat thallium-containing waste residue and achieve the effect of stable solidification of thallium.

[0066] Example 3

[0067] Compared with Example 2, in this example, only the temperature of the hydrothermal reactor is adjusted to 240° C., and other conditions remain unchanged.

[0068] Comparative Example 3

[0069] Compared with Example 2, in this example, only the temperature of the hydrothermal reactor is adjusted to 160° C., and other conditions remain unchanged.

[0070] Analysis example 2

[0071] In Example 2, Example 3 and Comparative Example 3, the content (mg / L) of each element in the treatment solution and the leaching toxicity (mg / L) of each element in the solid thallium treatment slag are shown in the following table:

[0072]

[0073] It can be seen that when the hydrothermal reaction is carried out at 160°C, the molecular structure of elemental sulfur has not yet undergone effective transformation, and its solidification effect on thallium will be greatly reduced. However, when the hydrothermal reaction is carried out at 180-240°C, thallium can be stably solidified from thallium-containing waste residue.

[0074] Example 4

[0075] Compared with Example 2, this example only adjusts the sulfur synthesis time to 10 days from the synthesis day, and other conditions remain unchanged.

[0076] Comparative Example 4

[0077] Compared with Example 2, this example only adjusts the time of synthesizing sulfur to 15 days from the synthesis day, and other conditions remain unchanged.

[0078] Analysis example 4

[0079] In Example 2, Example 4 and Comparative Example 4, the content (mg / L) of each element in the treatment solution and the leaching toxicity (mg / L) of each element in the solid thallium treatment slag are shown in the following table:

[0080]

[0081] It can be seen that although synthetic sulfur can achieve the solidification of thallium, when the synthetic sulfur is stored for more than 10 days, the solidification effect on thallium will be significantly reduced.

[0082] The above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention specification under the technical concept of the present invention, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for treating thallium-containing waste residue, characterized in that: Including steps: S1, providing synthetic sulfur within 10 days of the synthesis date; The synthetic sulfur synthesis process includes: mixing sulfite and sulfide in an acidic solution to obtain the synthetic sulfur; the molar ratio of the sulfite to the sulfide is 1:1.5-3.5; S2, subjecting the thallium-containing waste residue, the synthetic sulfur, and water to a hydrothermal reaction to obtain a treatment liquid and solid thallium treatment residue; Wherein, the temperature of the hydrothermal reaction is 180~240℃.

2. The processing method according to claim 1, characterized in that The sulfite includes sodium sulfite; the sulfide salt includes sodium sulfide nonahydrate; and the acidic solution includes sulfuric acid solution.

3. The processing method according to claim 1, characterized in that In step S1, the concentration of the acidic solution is 0.2-0.4 mol / L.

4. The processing method according to claim 1, characterized in that The mixing temperature in step S1 is 15-35°C.

5. The processing method according to claim 1, characterized in that The mixing time in step S1 is 2 to 24 hours.

6. The processing method according to claim 1, characterized in that In the step S2, the mass ratio of the thallium-containing waste residue to the synthetic sulfur is 1:0.5-1; the sum of the masses of the thallium-containing waste residue and the synthetic sulfur: the volume of the water is 1-2 g:1 mL.

7. The processing method according to claim 1, characterized in that The duration of the hydrothermal reaction is 12 to 24 hours.

8. The processing method according to claim 1, characterized in that The thallium-containing waste residue also contains one or more of cadmium, copper and lead.

9. The processing method according to claim 1, characterized in that: The thallium-containing waste residue includes one or more of copper slag, cobalt-nickel slag, lead slag, cadmium slag acid leaching residue and high-fluorine and chlorine fly ash generated during the smelting process.

10. The processing method according to any one of claims 1 to 9, characterized in that: The step S2 further includes: before performing the hydrothermal reaction, mixing the thallium-containing waste residue, the synthetic sulfur, and the water.

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