Heavy metal removal device

Abstract

The utility model relates to the related technical field of zinc-containing wastewater treatment, in particular to a heavy metal removal device which comprises a pH reaction tank and a coagulation reaction tank, and the discharge end of the coagulation reaction tank is sequentially connected with at least two second sedimentation tanks and a filter press; at least three first sedimentation tanks are arranged between the pH reaction tank and the coagulation reaction tank, and the first sedimentation tanks are further connected with sedimentation filters. The method comprises the following steps: adding a pre-prepared sodium hydroxide solution into a pH reaction tank in a controlled flow manner, continuously stirring, fully mixing and reacting zinc-containing wastewater with the sodium hydroxide solution to generate zinc hydroxide precipitate, and enabling the zinc hydroxide precipitate to flow into a three-stage zinc hydroxide precipitation tank from the bottom of the pH reaction tank, thereby realizing the recovery of high-purity zinc hydroxide. And meanwhile, the zinc-containing wastewater and the sodium hydroxide solution are fully mixed, so that the concentration of zinc ions in water is greatly reduced, the use amount of materials such as a flocculating agent in subsequent procedures is greatly reduced, and the production cost is directly reduced.

Description

Technical Field

[0001] The utility model relates to the technical field related to zinc-containing wastewater treatment, in particular to a heavy metal removal device. Background Art

[0002] Heavy metal catalysts are often used in chemical reactions in the pharmaceutical industry. For example, phenolphthalein is produced by heating phthalic anhydride and phenol, using sulfuric acid as a dehydrating agent and zinc chloride as a condensing agent. After separation and purification of the main components, the zinc salt is transferred to the wash solution (wastewater). Zinc is a heavy metal, and excessive discharge is harmful to the environment. Therefore, subsequent wastewater treatment processes must remove this zinc ion to ensure that its content remains within the legal limit (5 ppm) upon discharge.

[0003] Existing technologies typically treat this type of heavy metal-containing wastewater using graded flocculation and sedimentation. This involves first adjusting the wastewater's pH, then adding a flocculant for precipitation. After precipitation, the supernatant (and the filtrate from the precipitation) undergoes repeated pH adjustment, flocculant addition, and precipitation and filtration. Typically, a single flocculation cycle yields a filtrate with a low heavy metal ion content. The residues from each filter are then treated as solid waste (e.g., buried).

[0004] The advantage of this technical solution is that it can reduce the heavy metal ion content to a lower level, but the production efficiency is low, the daily processing volume is very limited, the amount of flocculant used in the production process is large, the amount of solid waste generated is also large, and the cost of solid waste treatment is high. The bigger disadvantage is that heavy metal compounds that could have been recycled are directly treated as solid waste, which is a huge waste of limited natural resources. Utility Model Content

[0005] The purpose of the present invention is to provide a heavy metal removal device to solve the problems raised in the above background technology.

[0006] To achieve the above objectives, the present invention provides the following technical solutions:

[0007] A heavy metal removal device comprises a pH reaction tank and a coagulation reaction tank, wherein the discharge end of the coagulation reaction tank is sequentially connected to at least two second sedimentation tanks and a filter press;

[0008] At least three first sedimentation tanks are arranged between the pH reaction tank and the coagulation reaction tank. The first sedimentation tanks are also connected to a sedimentation filter. The filtrate filtered out by the sedimentation filter is transported to the coagulation reaction tank.

[0009] The heavy metal removal device as described above: the pH reaction tank is connected to an alkali dosing tank for storing sodium hydroxide solution via a pump.

[0010] The heavy metal removal device as described above: the pH reaction tank and the coagulation reaction tank are both provided with stirring elements.

[0011] As for the heavy metal removal device described above: the liquid inlet of the coagulation reaction tank is arranged at the bottom of the coagulation reaction tank, and the upper end of the coagulation reaction tank is also connected to a delivery pump for adding flocculants.

[0012] The heavy metal removal device as described above: the inner bottoms of the first sedimentation tank, the coagulation reaction tank and the second sedimentation tank are all provided with aeration pipes.

[0013] The heavy metal removal device as described above: the liquid inlet of the first sedimentation tank is lower than the liquid outlet.

[0014] Compared with the prior art, the utility model has the following beneficial effects: by controlling the flow of a pre-prepared sodium hydroxide solution into a pH reaction tank and continuously stirring, the zinc-containing wastewater and the sodium hydroxide solution are fully mixed and reacted to generate zinc hydroxide precipitate, which flows from the bottom of the pH reaction tank into a tertiary zinc hydroxide precipitation tank, thereby realizing the recovery of high-purity zinc hydroxide; at the same time, the zinc-containing wastewater and the sodium hydroxide solution are fully mixed, so that the zinc ion concentration in the water is greatly reduced, the use of materials such as flocculants in subsequent processes is greatly reduced, and the production cost is directly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the structure of the heavy metal removal device.

[0016] In the figure: 1- alkali dosing tank, 2- pH reaction tank, 3- first sedimentation tank, 4- sedimentation filter, 5- coagulation reaction tank, 6- second sedimentation tank, 7- filter press. DETAILED DESCRIPTION

[0017] Various exemplary embodiments, features, and aspects of the present application will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0018] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0019] In addition, numerous specific details are provided in the following specific examples to better illustrate the present application. Those skilled in the art will appreciate that the present application can be practiced without certain specific details. In some instances, methods, means, and components well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.

[0020] The utility model aims to provide a heavy metal removal device for effectively removing zinc ions from wastewater and achieving the purpose of recovering zinc hydroxide. The specific implementation method is as follows:

[0021] See also Figure 1 In an embodiment of the utility model, a heavy metal removal device includes a pH reaction tank 2 and a coagulation reaction tank 5, the discharge end of the coagulation reaction tank 5 is connected to at least two second sedimentation tanks 6 and a filter press 7 in sequence; at least three first sedimentation tanks 3 are arranged between the pH reaction tank 2 and the coagulation reaction tank 5, the first sedimentation tank 3 is also connected to a sedimentation filter 4, and the filtrate filtered out by the sedimentation filter 4 is transported to the coagulation reaction tank 5.

[0022] In this embodiment, the pre-prepared sodium hydroxide solution is added to the pH reaction tank 2 under controlled flow and continuously stirred to fully mix and react with the zinc-containing wastewater and the sodium hydroxide solution to generate a zinc hydroxide precipitate, which flows from the bottom of the pH reaction tank 2 into the tertiary zinc hydroxide precipitation tank, thereby realizing the recovery of high-purity zinc hydroxide. At the same time, the zinc-containing wastewater and the sodium hydroxide solution are fully mixed, so that the zinc ion concentration in the water is greatly reduced, and the use of materials such as flocculants in subsequent processes is greatly reduced, which directly reduces the production cost.

[0023] Furthermore, the pH reaction tank 2 is connected to the alkali dosing tank 1 for storing sodium hydroxide solution through a pump. After the zinc-containing wastewater is added to the pH reaction tank 2, an appropriate amount of sodium hydroxide solution is pumped into the pH reaction tank 2 by the pump to achieve a mixed reaction between the zinc-containing wastewater and the sodium hydroxide solution.

[0024] In order to improve the reaction and coagulation effects, stirring elements are provided in the pH reaction tank 2 and the coagulation reaction tank 5. Exemplarily, in one embodiment, the stirring element includes a mounting frame installed on the pH reaction tank 2 or the coagulation reaction tank 5 and a motor installed on the mounting frame. A stirring shaft is fixed on the output shaft of the motor, and stirring blades are provided on the stirring shaft. When the motor is working, the stirring shaft and the stirring blades are driven to rotate synchronously, thereby improving the stirring effect. First, when the stirring element in the pH reaction tank 2 is working, sodium hydroxide and zinc ions are fully exchanged to increase the reaction rate; second, when the stirring element in the coagulation reaction tank 5 is working, the flocculant and wastewater are fully mixed to increase the coagulation rate.

[0025] In this embodiment, the liquid inlet of the coagulation reaction tank 5 is arranged at the bottom of the coagulation reaction tank 5, and the upper end of the coagulation reaction tank 5 is also connected to a delivery pump for adding flocculant. The waste liquid in the coagulation reaction tank 5 enters from the bottom and flows out from the top; at the same time, an appropriate amount of flocculant solution is added from the top through the delivery pump, and it is continuously stirred to allow sufficient contact reaction to immediately generate a suspension.

[0026] Preferably, the inner bottoms of the first sedimentation tank 3, the coagulation reaction tank 5 and the second sedimentation tank 6 are all provided with aeration pipes to treat sediments lacking fluidity, and the aeration pipes are connected to an aeration device, which includes but is not limited to a blower.

[0027] The liquid inlet of each of the first sedimentation tanks 3 is lower than the liquid outlet, so that the reaction liquid flowing through it can be fully precipitated. After the precipitation accumulates to a certain extent, the precipitate flows out from the bottom of the tank, is filtered through a filter, and the filtrate is discharged to the coagulation reaction tank 5. The precipitate is washed and dried to obtain zinc hydroxide with high purity, which is a valuable recyclable material.

[0028] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed within the present invention. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0029] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A heavy metal removal device, comprising a pH reaction tank (2) and a coagulation reaction tank (5), wherein the discharge end of the coagulation reaction tank (5) is sequentially connected to at least two second sedimentation tanks (6) and a filter press (7); It is characterized by: At least three first sedimentation tanks (3) are arranged between the pH reaction tank (2) and the coagulation reaction tank (5), and the first sedimentation tank (3) is also connected to a sedimentation filter (4), and the filtrate filtered out of the sedimentation filter (4) is transported to the coagulation reaction tank (5).

2. A heavy metal removal device according to claim 1, characterized in that: The pH reaction tank (2) is connected to the alkali dosing tank (1) for storing sodium hydroxide solution via a pump.

3. The heavy metal removal device according to claim 1, characterized in that: The pH reaction tank (2) and the coagulation reaction tank (5) are both provided with stirring elements.

4. The heavy metal removal device according to claim 1, characterized in that: The liquid inlet of the coagulation reaction tank (5) is arranged at the bottom of the coagulation reaction tank (5), and the upper end of the coagulation reaction tank (5) is also connected to a delivery pump for adding flocculant.

5. The heavy metal removal device according to claim 1, characterized in that: Aeration pipes are provided at the inner bottoms of the first sedimentation tank (3), the coagulation reaction tank (5) and the second sedimentation tank (6).

6. The heavy metal removal device according to claim 1, characterized in that: The liquid inlet of the first sedimentation tank (3) is lower than the liquid outlet.

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