Method for separating and recycling heavy metal ions in wastewater

Abstract

The invention discloses a method for separating and recovering heavy metal ions in wastewater, which belongs to the technical field of heavy metal ion recovery, and comprises the following steps: mixing wastewater containing metal ions with a medicament step by step, stirring, adding a polysaccharide organic reagent, inflating, and scraping bubbles. According to the method for separating and recycling the heavy metal ions in the waste water, valuable metals in the waste water can be recycled, the recycling efficiency is high, the valuable metals can be separated step by step, the medicaments are added into the waste water containing the metal ions step by step, the metal ions are recycled, and the recycling efficiency is high. And air flotation recovery can be carried out without using flotation reagents such as a collecting agent, and operation is simple and easy.

Description

Technical Field

[0001] The invention 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 Art

[0002] Wastewater containing heavy metals mainly comes from mining, mechanical processing, non-ferrous metal smelting, waste battery waste treatment, electroplating plant drainage, printed circuit board production drainage, and wastewater discharged from the production process of pesticides, medicines, paints, pigments, etc. Heavy metals discharged with water, even at low concentrations, may cause serious harm through bioaccumulation. Among these heavy metals, some are trace elements necessary for life activities, such as zinc, copper, and manganese, but excessive intake will cause harm to humans, animals, and plants. Some are also valuable metals that will be discharged along with the discharge of 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, wetland and microbial methods, but there are still problems such as low treatment efficiency, large amount of sediment sludge (hazardous waste), difficulty in sludge-water separation, small adsorbent capacity, high cost, no energy saving, complex operation and difficulty in fixing and recovering heavy metal ions. In particular, the valuable metals in the wastewater are precious mineral resources but have not been effectively mineralized, fixed and recycled. Summary of the invention

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

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

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

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

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

[0009] Preferably, the dosage of the polysaccharide organic reagent is 0.5-5 mg / L.

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

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

[0012] Therefore, the present invention adopts the above-mentioned method for separating and recovering heavy metal ions in wastewater, which has the following beneficial effects: (1) It can recover valuable metals in wastewater. By adjusting the dosage of reagents mixed with metals step by step, the purpose of separating valuable metals step by step can be achieved; (2) By adding polysaccharide reagents to wastewater containing metal ions, the morphology of the product formed by the metal ions and the mixed reagents can be regulated for recovery, and flotation recovery can be performed without using flotation reagents such as collectors; (3) The method of the present invention is used to recover heavy metal ions with high recovery efficiency.

[0013] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a particle size distribution diagram of Example 1 of a method for separating and recovering heavy metal ions in wastewater according to the present invention, wherein Figure 1 (a) is the particle size distribution diagram of the product separated and recovered from the lead metal ion wastewater. Figure 1 (b) is a particle size distribution diagram of the product separated and recovered from wastewater containing zinc metal ions; Figure 2 is a particle size distribution diagram of Example 2 of a method for separating and recovering heavy metal ions in wastewater according to the present invention, wherein Figure 2 (a) is the particle size distribution diagram of the product separated and recovered from the lead metal ion wastewater. Figure 2 (b) is a particle size distribution diagram of the product separated and recovered from wastewater containing zinc metal ions; Figure 3 is a particle size distribution diagram of Example 3 of a method for separating and recovering heavy metal ions in wastewater according to the present invention, wherein Figure 3 (a) is the particle size distribution diagram of the product separated and recovered from the lead metal ion wastewater. Figure 3 (b) is the particle size distribution diagram of the product separated and recovered from zinc metal ion-containing wastewater. DETAILED DESCRIPTION

[0015] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0016] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0017] The present invention provides a method for separating and recovering heavy metal ions in wastewater, comprising the following steps: mixing the wastewater containing metal ions with a reagent in steps, wherein the mass ratio of the total metal ions in the wastewater containing metal ions to the reagent is 1:1-1:5. Then stirring for 5-10 minutes, adding 0.5-5 mg / L of a polysaccharide organic reagent, aerating and scraping the bubbles, the aeration rate is 0.2-1 L / min, and the aeration time is 5-20 minutes.

[0018] The agent is one or two of sodium diethyldithiocarbamate, sodium sulfide, and trisodium trimercapto-s-triazine, and the polysaccharide organic agent includes one of cationic starch, anionic starch, amphoteric starch, sodium alginate, and carboxymethyl cellulose.

[0019] The metal ions and reagents in the wastewater are mixed step by step to form water-insoluble products, and then the polysaccharide organic reagents are used to regulate their morphology and size, and they are separated step by step through flotation.

[0020] Example 1 The invention 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 diethyldithiocarbamate in steps, first mixing the wastewater containing lead metal ions according to a mass ratio of lead metal ions to sodium diethyldithiocarbamate of 1:1, then stirring for 5 minutes, and then adding 0.5 mg / L of cationic starch, and obtaining a product with a d50 particle size value and a d90 particle size value of 9.72 μm and 26.96 μm, respectively. Figure 1 As shown in (a), the bubbles are scraped after inflation, the inflation rate is 0.2L / min, and the inflation time is 5min.

[0021] Then, the wastewater containing zinc metal ions was mixed with sodium diethyldithiocarbamate in a mass ratio of 1:1, stirred for 5 minutes, and then 0.5 mg / L of cationic starch was added. The d50 and d90 particle sizes of the obtained products were 8.34 μm and 21.78 μm, respectively. Figure 1 As shown in (b), the bubbles are scraped after inflation, the inflation rate is 0.2L / min, the inflation time is 5min, and the removal rates of lead ions and zinc ions in the wastewater are 96.8% and 94.3%, respectively.

[0022] Example 2 The invention 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 the wastewater containing lead metal ions according to a mass ratio of lead metal ions to sodium sulfide of 1:3, then stirring for 8 minutes, and then adding 3 mg / L of anionic starch, and obtaining a product d50 particle size value and d90 particle size value of 46.18 μm and 95.36 μm respectively, such as Figure 2 As shown in (a), the bubbles are scraped after inflation, the inflation rate is 0.5L / min, and the inflation time is 10min.

[0023] Then, the wastewater containing zinc metal ions was mixed with sodium sulfide at a mass ratio of 1:3, stirred for 8 minutes, and then 3 mg / L of anionic starch was added. The d50 and d90 particle sizes of the products were 31.22 μm and 59.85 μm, respectively. Figure 2 As shown in (b) in the figure, the bubbles were scraped after aeration, the aeration rate was 0.5L / min, the aeration time was 10min, and the removal rates of lead ions and zinc ions in the wastewater were 98.8% and 97.3%, respectively.

[0024] Example 3 The invention 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 trithiolate in steps, firstly mixing the wastewater containing lead metal ions according to a mass ratio of lead metal ions to trisodium trithiolate of 1:5, then stirring for 10 minutes, and then adding 5 mg / L of amphoteric starch, and obtaining a product with a d50 particle size value and a d90 particle size value of 27.25 μm and 62.89 μm, respectively. Figure 3 As shown in (a), the bubbles are scraped after inflation, the inflation rate is 1L / min, and the inflation time is 20min.

[0025] Then, the wastewater containing zinc metal ions was mixed with trithiocarbazine triazine at a mass ratio of 1:5, stirred for 10 minutes, and then 5 mg / L of amphoteric starch was added. The d50 and d90 particle sizes of the obtained products were 20.92 μm and 41.31 μm, respectively. Figure 3 As shown in (b), the bubbles are scraped after inflation, the inflation rate is 1L / min, the inflation time is 20min, and the removal rates of lead ions and zinc ions in the wastewater are 96.8% and 96.3%, respectively.

[0026] Therefore, the present invention adopts the above-mentioned method for separating and recovering heavy metal ions in wastewater, which can recover valuable metals in wastewater with high recovery efficiency and can be separated in steps. By adding reagents to wastewater containing metal ions, the metal ions can be recovered, and flotation recovery can be performed without using flotation agents such as collectors. The operation is simple and easy to operate.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for separating and recovering heavy metal ions in wastewater, characterized in that: The following steps are involved: The wastewater containing metal ions is mixed with the reagents in steps, then stirred, and then the polysaccharide organic reagent is added, and the foam is scraped after aeration.

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 to the reagent in the wastewater containing metal ions 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 agent is one or two of sodium diethyldithiocarbamate, sodium sulfide, and trisodium trithiodiazine.

4. The method for separating and recovering heavy metal ions in wastewater according to claim 1, characterized in that: The polysaccharide organic agent includes one of cationic starch, anionic starch, amphoteric starch, sodium alginate and carboxymethyl cellulose.

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

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

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

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