Water treatment agent for advanced treatment of nonferrous metallurgy thallium-containing wastewater

Abstract

The invention relates to a water treatment agent for advanced treatment of thallium-containing wastewater in nonferrous metallurgy. The water treatment agent is prepared by fully mixing and uniformly stirring the following raw materials in parts by weight: 50-80 parts of a sodium diethyldithiocarbamate aqueous solution with the mass concentration of 5%-15%, 10-40 parts of sulfide or polysulfide and 10-40 parts of sodium thiosulfate. The water treatment agent provided by the invention can realize efficient removal of heavy metal ions, does not need a subsequent treatment process, not only simplifies the treatment process, but also reduces the treatment cost.

Description

Technical Field

[0001] This invention relates to the field of water treatment agents and environmental engineering for the treatment of heavy metal wastewater in the non-ferrous metal smelting industry, and particularly to a water treatment agent for the deep treatment of thallium-containing wastewater in non-ferrous smelting. Background Technology

[0002] Thallium-containing wastewater in non-ferrous smelting processes mainly originates from waste acid generated during flue gas scrubbing in smelting and acid production, process water generated during production, wash water generated during workshop floor washing, and initial rainwater. Thallium in the wastewater includes Ti. + and Tl 3+ Two forms, and Tl + Content higher than Tl 3+ Taking lead-zinc smelting wastewater as an example, generally Tl + It accounts for about 70%, Tl 3+ It accounts for about 30%. Arsenate, sulfate, fluoride, and chloride anions in the wastewater can also react with Ti. + 、Tl 3+ It forms a variety of stable ligands, such as TlSO. - 4. TlCl - Grade 4. Thallium-containing wastewater generated during different non-ferrous metal smelting processes also contains valuable components such as copper, zinc, lead, nickel, mercury, cadmium, chromium, and arsenic.

[0003] Traditional treatment methods for thallium-containing wastewater generally involve chemical precipitation. This method uses reactions such as precipitation and flocculation to convert thallium ions in the wastewater into thallium-containing precipitates, which are then removed through solid-liquid separation. This includes oxidation precipitation and sulfide precipitation. Oxidation precipitation uses lime to adjust the pH value; however, when the pH exceeds 8, thallium... 3+ Tl(OH)3 will be generated, and the Ksp of Tl(OH)3 is very small (10⁻⁶). -45.2 ), and completely precipitates in solution. But Tl + It is highly soluble, does not form precipitable hydroxides, and is difficult to adsorb by conventional materials. Instead, it requires the addition of large amounts of strong oxidizing agents, such as potassium permanganate and sodium hypochlorite, to precipitate the water-soluble Tl. + Oxidation to Tl 3+ Then make Tl 3+ Under alkaline conditions, hydroxide precipitates are formed. This oxidation precipitation method is not only costly but also introduces other impurity ions, causing secondary pollution. The sulfide precipitation method involves adding sulfides to the wastewater, causing dissolved Tl... + Transformed into Tl2S precipitate (Ksp=5×10) -21 However, Tl2S precipitates have small and unstable particle sizes, and are prone to generating H2S during use, causing secondary pollution, which makes practical application difficult.

[0004] Therefore, traditional treatment methods cannot achieve emission standards for thallium, and advanced treatment is required, such as adding adsorption, membrane separation and other subsequent treatment processes to meet emission requirements. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a water treatment agent for the deep treatment of thallium-containing wastewater in non-ferrous smelting, which achieves efficient removal of heavy metal ions.

[0006] To solve the above problems, the present invention provides a water treatment agent for the deep treatment of thallium-containing wastewater from non-ferrous smelting, characterized in that: the water treatment agent is prepared by fully mixing and stirring the following raw materials in parts by weight: 50-80 parts of sodium diethyldithiocarbamate aqueous solution with a mass concentration of 5%-15%, 10-40 parts of sulfide or polysulfide, and 10-40 parts of sodium thiosulfate.

[0007] The sodium diethyldithiocarbamate aqueous solution is prepared by the following method: first, water is added to the reaction vessel and stirring is started; then, alkali is added to the reaction vessel to obtain an alkali solution with a mass concentration of 10%~20%; cooling water is turned on to cool the solution; then diethylamine is added to the reaction vessel and mixed evenly; carbon disulfide is then slowly added dropwise, with the rate of addition of carbon disulfide being such that the reaction temperature does not exceed 30°C; after the addition is complete, the reaction is kept at 40°C for 1 hour; if sodium diethyldithiocarbamate crystals are present in the reaction vessel after the reaction is completed, water is added to the reaction vessel and stirred until all the crystals are dissolved to obtain the sodium diethyldithiocarbamate aqueous solution.

[0008] The alkali is solid sodium hydroxide or liquid sodium hydroxide with a mass concentration of 30% to 50%.

[0009] The molar ratio of sodium hydroxide, carbon disulfide, and diethylamine in the alkali is 1.02:1.02:1.

[0010] The sulfide is sodium sulfide, and the polysulfide is sodium polysulfide.

[0011] The preparation method of the water treatment agent for the deep treatment of thallium-containing wastewater in non-ferrous smelting, as described above, is characterized by: firstly preparing a sodium diethyldithiocarbamate aqueous solution with a mass concentration of 5% to 15% in a reaction vessel; then, by weight, adding 10 to 40 parts of sodium thiosulfate and 10 to 40 parts of sulfide or polysulfide sequentially to 50 to 80 parts of the sodium diethyldithiocarbamate aqueous solution, and mixing thoroughly and stirring evenly to obtain the final product.

[0012] Compared with the prior art, the present invention has the following advantages: 1. This invention is composed of a variety of agents that have a high efficiency in removing thallium, such as sulfides, polysulfides, thiosulfates, and DTC chelating agents. It contains functional groups such as mercapto, thiocarbonyl, and amino groups. It can use its special functional groups to undergo a strong chelation reaction with various heavy metal ions in wastewater, especially thallium, to generate chelate precipitates that are insoluble or sparingly soluble in water, thereby achieving efficient removal of heavy metal ions.

[0013] 2. The water treatment agent described in this invention can stably remove heavy metal elements such as thallium that cannot be removed by traditional chemical precipitation methods. Without the need for additional subsequent treatment processes such as adsorption and membrane separation, the heavy metals such as thallium in wastewater can be stably discharged in compliance with standards. This not only simplifies the treatment process but also reduces the treatment cost.

[0014] 3. The wastewater treatment agent of this invention requires a small dosage, and the treated water has low hardness, produces a small amount of slag, and the slag has a high metal content that can be comprehensively utilized. Detailed Implementation

[0015] A water treatment agent for the deep treatment of thallium-containing wastewater from non-ferrous smelting is prepared by thoroughly mixing and stirring the following raw materials in parts by weight (g): 50-80 parts of sodium diethyldithiocarbamate aqueous solution with a mass concentration of 5%-15%, 10-40 parts of sulfide or polysulfide, and 10-40 parts of sodium thiosulfate.

[0016] The sodium diethyldithiocarbamate aqueous solution was prepared as follows: First, water was added to the reaction vessel and stirring was started. Then, alkali was added to the reaction vessel to obtain an alkali solution with a mass concentration of 10%–20%, where the alkali was solid sodium hydroxide or liquid sodium hydroxide with a mass concentration of 30%–50%. The mixture was cooled with cooling water. Then, diethylamine was added to the reaction vessel and mixed thoroughly. Carbon disulfide was then slowly added dropwise, with the rate of addition kept below 30°C. After the addition was complete, the reaction was maintained at 40°C for 1 hour. If sodium diethyldithiocarbamate crystals remained in the reaction vessel after the reaction, water was added and stirred until all the crystals dissolved, thus obtaining the sodium diethyldithiocarbamate aqueous solution. During the preparation process, the molar ratio of sodium hydroxide, carbon disulfide, and diethylamine in the alkali was 1.02:1.02:1 (n...). NaOH :n CS2 :n C4H11N =1.02:1.02:1).

[0017] The sulfide is sodium sulfide, and the polysulfide is sodium polysulfide.

[0018] The preparation method of this water treatment agent is as follows: First, prepare a sodium diethyldithiocarbamate aqueous solution with a mass concentration of 5% to 15% in a reaction vessel. Then, according to the weight, add 10 to 40 parts of sodium thiosulfate and 10 to 40 parts of sulfide or polysulfide to 50 to 80 parts of the sodium diethyldithiocarbamate aqueous solution. After thorough mixing and stirring, the solution is obtained.

[0019] Example 1: Using 30% liquid sodium hydroxide as a raw material, a 15% alkaline solution was obtained by diluting it with water. The solution was cooled with cooling water, and then a certain amount of diethylamine was added to the reaction vessel. After mixing thoroughly, a certain amount of carbon disulfide was slowly added dropwise, with the rate of addition ensuring the reaction temperature did not exceed 30°C. The molar ratio of the three raw materials was sodium hydroxide:carbon disulfide:diethylamine = 1.02:1.02:1. After the addition was complete, the reaction was maintained at 40°C for 1 hour. After the reaction was complete, water was added to the reaction vessel and stirred until all the crystals dissolved, yielding a 10% sodium diethyldithiocarbamate aqueous solution.

[0020] Take 60 parts of the above sodium diethyldithiocarbamate aqueous solution, add 10 parts of sodium thiosulfate and 30 parts of sodium sulfide to it, mix thoroughly and stir evenly to obtain the water treatment agent.

[0021] Example 2: Using solid sodium hydroxide as a raw material, a 10% alkaline solution was obtained by diluting it with water. The solution was cooled with cooling water, and then a certain amount of diethylamine was added to the reaction vessel. After mixing thoroughly, a certain amount of carbon disulfide was slowly added dropwise, with the rate of addition controlled to ensure the reaction temperature did not exceed 30°C. The molar ratio of the three raw materials was sodium hydroxide:carbon disulfide:diethylamine = 1.02:1.02:1. After the addition was complete, the reaction was maintained at 40°C for 1 hour. After the reaction was complete, water was added to the reaction vessel and stirred until all the crystals dissolved, yielding a 5% sodium diethyldithiocarbamate aqueous solution.

[0022] Take 50 parts of the above sodium diethyldithiocarbamate aqueous solution, add 10 parts of sodium thiosulfate and 40 parts of sodium sulfide to it, mix thoroughly and stir evenly to obtain the water treatment agent.

[0023] Example 3: Using 50% liquid sodium hydroxide as a raw material, a 20% alkaline solution was obtained by diluting it with water. The solution was cooled with cooling water, and then a certain amount of diethylamine was added to the reaction vessel. After mixing thoroughly, a certain amount of carbon disulfide was slowly added dropwise, with the rate of addition ensuring the reaction temperature did not exceed 30°C. The molar ratio of the three raw materials was sodium hydroxide:carbon disulfide:diethylamine = 1.02:1.02:1. After the addition was complete, the reaction was maintained at 40°C for 1 hour. After the reaction was complete, water was added to the reaction vessel and stirred until all the crystals dissolved, yielding a 15% aqueous solution of sodium diethyldithiocarbamate.

[0024] Take 70 parts of the above sodium diethyldithiocarbamate aqueous solution, add 10 parts of sodium thiosulfate and 20 parts of sodium sulfide to it, mix thoroughly and stir evenly to obtain the water treatment agent.

[0025] Example 4: Using 30% liquid sodium hydroxide as a raw material, a 15% alkaline solution was obtained by diluting it with water. The solution was cooled with cooling water, and then a certain amount of diethylamine was added to the reaction vessel. After mixing thoroughly, a certain amount of carbon disulfide was slowly added dropwise, with the rate of addition ensuring the reaction temperature did not exceed 30°C. The molar ratio of the three raw materials was sodium hydroxide:carbon disulfide:diethylamine = 1.02:1.02:1. After the addition was complete, the reaction was maintained at 40°C for 1 hour. After the reaction was complete, water was added to the reaction vessel and stirred until all the crystals dissolved, yielding a 10% sodium diethyldithiocarbamate aqueous solution.

[0026] Take 80 parts of the above sodium diethyldithiocarbamate aqueous solution, add 10 parts of sodium thiosulfate and 10 parts of sodium sulfide to it, mix thoroughly and stir evenly to obtain the water treatment agent.

[0027] Example 5: Using 50% liquid sodium hydroxide as a raw material, a 15% alkaline solution was obtained by diluting it with water. The solution was cooled with cooling water, and then a certain amount of diethylamine was added to the reaction vessel. After mixing thoroughly, a certain amount of carbon disulfide was slowly added dropwise, with the rate of addition ensuring the reaction temperature did not exceed 30°C. The molar ratio of the three raw materials was sodium hydroxide:carbon disulfide:diethylamine = 1.02:1.02:1. After the addition was complete, the reaction was maintained at 40°C for 1 hour. After the reaction was complete, water was added to the reaction vessel and stirred until all the crystals dissolved, yielding a 10% sodium diethyldithiocarbamate aqueous solution.

[0028] Take 50 parts of the above sodium diethyldithiocarbamate aqueous solution, add 20 parts of sodium thiosulfate and 30 parts of sodium sulfide to it, mix thoroughly and stir evenly to obtain the water treatment agent.

[0029] To more intuitively illustrate the impact of changes in the weight of raw materials on the treatment effect of non-ferrous metal smelting wastewater in different embodiments, the same lead-zinc wastewater was selected and water treatment experiments were conducted under the same conditions. The content and removal rate of the main heavy metal pollutants in the treated water samples were listed respectively. By comparing with the special discharge standard limit of the "Emission Standard of Pollutants for Lead and Zinc Industry" (GB25466-2010), the effect of the water treatment agent was reflected.

[0030] The wastewater treated in the water treatment experiment was industrial wastewater from a lead-zinc smelter. The heavy metal pollutants in the wastewater included Zn 16.03 mg / L, Pb 0.14 mg / L, Cd 0.78 mg / L, Tl 0.82 mg / L, Cu 0.0058 μg / L, and Hg 0.073 mg / L.

[0031] The water treatment test method was as follows: 1L of the above wastewater was taken, and a certain amount of lime was added to adjust the pH value of the wastewater to 9-11. After stirring for 10 minutes, 0.5ml of the water treatment agent obtained in Examples 1-5 was added and stirred for 10 minutes. Finally, 1ml of flocculant PAM (0.1% aqueous solution) was added and stirred for 5 minutes. After standing and filtering, the treated water sample was obtained. The pH value was adjusted back to about 7 with acid, and the concentration of residual heavy metal ions in the water sample was detected. The test results are shown in Table 1.

[0032] Table 1 As can be seen from Table 1, when the water treatment agent of the present invention is used to treat thallium-containing wastewater from lead and zinc smelting, the treated water quality meets the special discharge standard limit requirements of the "Emission Standard of Pollutants for Lead and Zinc Industry" (GB25466-2010).

Claims

1. A water treatment agent for the deep treatment of thallium-containing wastewater from non-ferrous smelting, characterized in that: The water treatment agent is prepared by thoroughly mixing and stirring the following raw materials in parts by weight: 50-80 parts of sodium diethyldithiocarbamate aqueous solution with a mass concentration of 5%-15%, 10-40 parts of sulfide or polysulfide, and 10-40 parts of sodium thiosulfate.

2. The water treatment agent for deep treatment of thallium-containing wastewater from non-ferrous smelting as described in claim 1, characterized in that: The sodium diethyldithiocarbamate aqueous solution is prepared by the following method: first, water is added to the reaction vessel and stirring is started; then, alkali is added to the reaction vessel to obtain an alkali solution with a mass concentration of 10%~20%; cooling water is turned on to cool the solution; then diethylamine is added to the reaction vessel and mixed evenly; carbon disulfide is then slowly added dropwise, with the rate of addition of carbon disulfide being such that the reaction temperature does not exceed 30°C; after the addition is complete, the reaction is kept at 40°C for 1 hour; if sodium diethyldithiocarbamate crystals are present in the reaction vessel after the reaction is completed, water is added to the reaction vessel and stirred until all the crystals are dissolved to obtain the sodium diethyldithiocarbamate aqueous solution.

3. The water treatment agent for deep treatment of thallium-containing wastewater from non-ferrous smelting as described in claim 2, characterized in that: The alkali is solid sodium hydroxide or liquid sodium hydroxide with a mass concentration of 30% to 50%.

4. A water treatment agent for deep treatment of thallium-containing wastewater from non-ferrous smelting as described in claim 2, characterized in that: The molar ratio of sodium hydroxide, carbon disulfide, and diethylamine in the alkali is 1.02:1.02:

1.

5. A water treatment agent for deep treatment of thallium-containing wastewater from non-ferrous smelting as described in claim 1, characterized in that: The sulfide is sodium sulfide, and the polysulfide is sodium polysulfide.

6. The method for preparing a water treatment agent for deep treatment of thallium-containing wastewater from non-ferrous smelting as described in claim 1, characterized in that: First, prepare a sodium diethyldithiocarbamate aqueous solution with a mass concentration of 5% to 15% in a reaction vessel. Then, add 10 to 40 parts of sodium thiosulfate and 10 to 40 parts of sulfide or polysulfide to 50 to 80 parts of the sodium diethyldithiocarbamate aqueous solution by weight. After thorough mixing and stirring, the solution is obtained.

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