Method for separating and recovering heavy metal ions in wastewater

Abstract

The application discloses a method for separating and recovering heavy metal ions in wastewater, and belongs to the technical field of heavy metal ion recovery, and comprises the following steps: mixing wastewater containing metal ions with reagents step by step, then stirring, adding polysaccharide organic reagents, and scraping bubbles after aeration. The method for separating and recovering heavy metal ions in wastewater can recover valuable metals in wastewater, has high recovery efficiency, and can separate valuable metals step by step. The method can recover metal ions by adding reagents step by step in wastewater containing metal ions, and can not use flotation reagents such as collectors for air flotation recovery, so that the operation is simple and easy to operate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heavy metal ion recovery, in particular to a method for separating and recovering heavy metal ions in wastewater. BACKGROUND

[0002] Wastewater containing heavy metals mainly comes from mining, mechanical processing, non-ferrous metal smelting, waste battery garbage treatment, electroplating plant drainage, printed circuit board production drainage, and wastewater discharged in the production process of pesticides, medicines, paints, pigments, etc. Heavy metals discharged with water, even at low concentrations, can cause serious harm through biological enrichment. Among these heavy metals, some are trace elements necessary for life activities, such as zinc, copper, and manganese, but excessive intake will cause damage to humans, animals, and plants. Some are valuable metals that are discharged with wastewater.

[0003] At present, the main treatment methods for heavy metal acidic wastewater include neutralization, chemical precipitation, electrolytic deposition, extraction, ion exchange, membrane separation, adsorption, and wetland and microbial methods, but there are still problems such as low treatment efficiency, large amount of sludge (hazardous waste), difficulty in separating sludge and water, small adsorbent capacity, high cost, lack of energy saving, complex operation, and difficulty in fixing and recycling heavy metal ions. Especially, the valuable metals in wastewater are valuable mineral resources and have not been effectively mineralized and recycled. SUMMARY

[0004] The purpose of the present application is to provide a method for separating and recovering heavy metal ions in wastewater, which can recover valuable metals in wastewater, has high recovery efficiency, and can separate valuable metals step by step. By adding reagents step by step in wastewater containing metal ions, metal ions are recovered without using flotation reagents such as collectors, which is simple and easy to operate.

[0005] To achieve the above purpose, the present application provides a method for separating and recovering heavy metal ions in wastewater, comprising the following steps: mixing wastewater containing metal ions with reagents step by step, then stirring, adding a polysaccharide organic reagent, and scraping bubbles after aeration.

[0006] Preferably, the mass ratio of total metal ions in wastewater containing metal ions to reagents is 1:1-1:5.

[0007] Preferably, the reagent is one or two of sodium diethyldithiocarbamate, sodium sulfide, and trisodium trithione.

[0008] Preferably, the polysaccharide organic reagent includes one of cationic starch, anionic starch, amphoteric starch, sodium alginate, and carboxymethyl cellulose.

[0009] Preferably, the polysaccharide organic reagent is used in an amount of 0.5-5 mg / L.

[0010] Preferably, the aeration rate is 0.2-1 L / min, and the aeration time is 5-20 min.

[0011] Preferably, the stirring time is 5-10 min.

[0012] Therefore, the method for separating and recovering heavy metal ions in wastewater has the following beneficial effects:

[0013] (1) Valuable metals in wastewater can be recovered, and by adjusting and controlling the amount of mixed reagent mixed with the metal, the valuable metals can be separated step by step;

[0014] (2) By adding polysaccharide reagents to wastewater containing metal ions, the morphology of the product formed by the metal ions and the mixed reagent is controlled for recovery, which can be recovered by air flotation without using flotation reagents such as collectors;

[0015] (3) The method of the present application has high recovery efficiency for heavy metal ions.

[0016] The technical solutions of the present application will be described in further detail below with reference to the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a particle size distribution graph of a method for separating and recovering heavy metal ions in wastewater according to an embodiment 1 of the present application, wherein Figure 1 (a) in the above is a particle size distribution graph of the product obtained by separating and recovering lead-containing metal ions in wastewater, Figure 1 (b) in the above is a particle size distribution graph of the product obtained by separating and recovering zinc-containing metal ions in wastewater;

[0018] Figure 2 is a particle size distribution graph of a method for separating and recovering heavy metal ions in wastewater according to an embodiment 2 of the present application, wherein Figure 2 (a) in the above is a particle size distribution graph of the product obtained by separating and recovering lead-containing metal ions in wastewater, Figure 2 (b) in the above is a particle size distribution graph of the product obtained by separating and recovering zinc-containing metal ions in wastewater;

[0019] Figure 3 is a particle size distribution graph of a method for separating and recovering heavy metal ions in wastewater according to an embodiment 3 of the present application, wherein Figure 3 (a) in the above is a particle size distribution graph of the product obtained by separating and recovering lead-containing metal ions in wastewater, Figure 3 (b) in the above is a particle size distribution graph of the product obtained by separating and recovering zinc-containing metal ions in wastewater. DETAILED DESCRIPTION

[0020] The technical solutions of the present application are further described below with reference to the accompanying drawings and examples.

[0021] Unless otherwise defined, technical terms or scientific terms used in the present application shall have the usual meaning understood by a person with ordinary skill in the art to which the present application belongs.

[0022] The present application provides a method for separating and recovering heavy metal ions in wastewater, comprising the following steps: stepwise mixing of wastewater containing metal ions with reagents, wherein the mass ratio of total metal ions in wastewater containing metal ions to reagents is 1:1-1:5. After stirring for 5-10 min, 0.5-5 mg / L of polysaccharide organic reagent is added, and after aeration, the bubbles are scraped off, the aeration rate is 0.2-1 L / min, and the aeration time is 5-20 min.

[0023] The reagent is one or two of sodium diethyldithiocarbamate, sodium sulfide, and trisodium trithiazene, and the polysaccharide organic reagent includes one of cationic starch, anionic starch, amphoteric starch, sodium alginate, and carboxymethyl cellulose.

[0024] The stepwise mixing of metal ions in wastewater with reagents forms a product that is insoluble in water, and then the polysaccharide organic reagent controls the size and morphology of the product, which is separated step by step by air flotation.

[0025] Example 1

[0026] The present application provides a method for separating and recovering heavy metal ions in wastewater, comprising the following steps: stepwise mixing of wastewater containing lead and zinc metal ions with sodium diethyldithiocarbamate, first mixing wastewater containing lead metal ions according to a mass ratio of lead metal ions to sodium diethyldithiocarbamate of 1:1, then stirring for 5 min, and then adding 0.5 mg / L of cationic starch, to obtain a product with d50 particle size value and d90 particle size value of 9.72 μm and 26.96 μm, respectively, as shown in (a) of FIG. 1, after aeration, the bubbles are scraped off, the aeration rate is 0.2 L / min, and the aeration time is 5 min. Figure 1

[0027] Then, wastewater containing zinc metal ions is mixed according to a mass ratio of zinc metal ions to sodium diethyldithiocarbamate of 1:1, stirred for 5 min, and then 0.5 mg / L of cationic starch is added, to obtain a product with d50 particle size value and d90 particle size value of 8.34 μm and 21.78 μm, respectively, as shown in (b) of FIG. 1, after aeration, the bubbles are scraped off, the aeration rate is 0.2 L / min, and the aeration time is 5 min, and the removal rates of lead ions and zinc ions in wastewater are 96.8% and 94.3%, respectively. Figure 1

[0028] Example 2 ​​

[0029] The present application provides a method for separating and recovering heavy metal ions in wastewater, comprising the following steps: mixing wastewater containing lead and zinc metal ions with sodium sulfide in steps, first mixing wastewater containing lead metal ions according to the mass ratio of lead metal ions to sodium sulfide of 1:3, then stirring for 8 min, and then adding 3 mg / L of anionic starch, so that the d50 particle size value and the d90 particle size value of the obtained product are 46.18 μm and 95.36 μm, respectively, as shown in (a) of FIG. 1. Figure 2 After aeration, the bubbles are scraped, the aeration rate is 0.5 L / min, and the aeration time is 10 min.

[0030] Then, the wastewater containing zinc metal ions is mixed according to the mass ratio of zinc metal ions to sodium sulfide of 1:3, stirred for 8 min, and then 3 mg / L of anionic starch is added, so that the d50 particle size value and the d90 particle size value of the product are 31.22 μm and 59.85 μm, respectively, as shown in (b) of FIG. 1. Figure 2 After aeration, the bubbles are scraped, the aeration rate is 0.5 L / min, and the aeration time is 10 min, and the removal rates of lead ions and zinc ions in the wastewater are 98.8% and 97.3%, respectively.

[0031] Example 3

[0032] The present application provides a method for separating and recovering heavy metal ions in wastewater, comprising the following steps: mixing wastewater containing lead and zinc metal ions with trisodium trithiazene in steps, first mixing wastewater containing lead metal ions according to the mass ratio of lead metal ions to trisodium trithiazene of 1:5, then stirring for 10 min, and then adding 5 mg / L of amphoteric starch, so that the d50 particle size value and the d90 particle size value of the obtained product are 27.25 μm and 62.89 μm, respectively, as shown in (a) of FIG. 2. Figure 3 After aeration, the bubbles are scraped, the aeration rate is 1 L / min, and the aeration time is 20 min.

[0033] Then, the wastewater containing zinc metal ions is mixed according to the mass ratio of zinc metal ions to trisodium trithiazene of 1:5, stirred for 10 min, and then 5 mg / L of amphoteric starch is added, so that the d50 particle size value and the d90 particle size value of the product are 20.92 μm and 41.31 μm, respectively, as shown in (b) of FIG. 2. Figure 3 After aeration, the bubbles are scraped, the aeration rate is 1 L / min, and the aeration time is 20 min, and the removal rates of lead ions and zinc ions in the wastewater are 96.8% and 96.3%, respectively.

[0034] Therefore, the application can recover the valuable metals in the wastewater by using the above method for separating and recovering heavy metal ions in wastewater, has high recovery efficiency, and can be separated step by step.

[0035] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit them. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements should not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for separating and recovering heavy metal ions in wastewater, characterized by comprising the steps of: The method comprises the following steps: mixing the wastewater containing metal ions with the reagent step by step, then stirring, adding polysaccharide organic reagent, and scraping bubbles after aeration; ​ the reagent is one or two of sodium diethyldithiocarbamate, sodium sulfide and trisodium trithione; the polysaccharide organic reagent comprises one of cationic starch, anionic starch, amphoteric starch, sodium alginate and carboxymethyl cellulose.

2. The method for separating and recovering heavy metal ions in wastewater according to claim 1, characterized in that: the mass ratio of total metal ions in the wastewater containing metal ions to the reagent is 1:1-1:

5.

3. The method for separating and recovering heavy metal ions in wastewater according to claim 1, characterized in that: the dosage of the polysaccharide organic reagent is 0.5-5 mg / L.

4. The method for separating and recovering heavy metal ions in wastewater according to claim 1, characterized in that: the aeration rate is 0.2-1 L / min, and the aeration time is 5-20 min.

5. The method for separating and recovering heavy metal ions in wastewater according to claim 1, characterized in that: the stirring time is 5-10 min.

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