CN102442736B - Nickel ion separation and recovery device for treating wastewater on surface of aluminium material - Google Patents

Abstract

A nickel ion separation and recovery device for aluminum material surface treatment wastewater, which separates and recovers nickel ions by destroying the complexation of nickel ions and complexing agents. The device includes a waste water tank, a chemical reactor, a pH sensor, a pH meter, first to third dosing mechanisms and ion exchange equipment. The chemical reactor is connected to the wastewater tank to introduce the aluminum surface treatment wastewater. The first dosing mechanism is used to add acid to the waste water in the chemical reactor until the pH meter indicates that the pH value of the aluminum material surface treatment waste water is 2-2.5, so that the metal nickel and aluminum ions in complex state are released. The second dosing mechanism is used for adding an appropriate amount of aluminum to the waste water in the chemical reactor. The third dosing mechanism is used to add alkali to the chemical reactor until the pH meter indicates that the pH value of the wastewater has been adjusted to between 5.5 and 6.5, so that the complexing agent and the aluminum ion form a complex, and the aluminum in the non-complexed state The ions form a precipitate. Finally, the ion exchange equipment uses ion exchange technology to adsorb nickel ions retained in the wastewater.

Description

Nickel ion separation and recovery device for aluminum surface treatment wastewater

technical field

The invention relates to a device for separating and recovering nickel ions in waste water, which is used for treating waste water containing aluminum ions, nickel ions and complexing agents produced during the surface treatment of aluminum materials.

Background technique

Aluminum and aluminum alloy materials have a series of excellent physical, chemical, mechanical and processing properties, so they are widely used in decoration, construction, transportation, aerospace and other fields. However, aluminum and aluminum alloy materials also have shortcomings such as hardness, wear resistance, and corrosion resistance. In order to overcome these disadvantages, necessary surface treatment must be carried out.

Surface treatment generally includes degreasing, alkali etching, neutralization, anodizing, coloring, sealing and other processes. Surface treatment improves the surface performance of aluminum materials, but also produces various types of wastewater, one of which is wastewater and waste liquid from production processes such as coloring and sealing. This type of wastewater is characterized by containing metal nickel ions, aluminum ions and various organic or inorganic complexing agents. With the continuous improvement of environmental protection requirements, the problem of metal pollution in the aluminum processing industry has become increasingly prominent. In order to meet the requirements of environmental protection standards, most enterprises separate such nickel-containing wastewater from other wastewater and treat them separately.

Because wastewater contains a large amount of aluminum ions, the ion exchange technology disclosed in CN1762602 cannot separate nickel from wastewater. Therefore nickel must first be separated from the waste liquid.

The general treatment technology is to adjust this type of nickel-containing wastewater to alkalinity, so that nickel ions are converted into nickel hydroxide precipitates. Furthermore, the waste water is divided into solid and liquid two phases through sedimentation and filtration, the solid nickel hydroxide is sent to a qualified unit for treatment, and the liquid water is discharged. However, this conventional technology cannot meet the requirements of environmental protection, and the excessive phenomenon of heavy metal nickel ions is very common.

Some researchers choose the extraction method to separate and recover nickel resources from aluminum-nickel liquid. For example, Chinese Taiwan patent TW082107216 mentions an extractant that can be used to separate aluminum, cobalt and nickel ions in aqueous sulfuric acid solution. Patents such as JP08026124 and US19930163481 mention a method for extracting, separating and recovering nickel and cobalt from an aqueous solution containing a large amount of aluminum ions with an extractant. However, the extraction method has the disadvantages of complex process, expensive extractant, and high equipment cost.

Contents of the invention

The inventors of the present application have found through research that the cause of nickel ions exceeding the standard is that the coloring and sealing solutions contain complexing agents that can form stable complexes with nickel ions, such as citric acid, ammonia water, fluoride ions, etc. Once nickel ions are complexed with these complexing agents, they are very stable and hinder the formation of nickel hydroxide. The soluble complexed nickel causes the wastewater to exceed the standard.

In view of this, the present invention proposes a nickel ion separation and recovery device for aluminum surface treatment wastewater. The device separates and recovers nickel ions by destroying the complexation between nickel ions and complexing agents.

The nickel ion separation and recovery device for aluminum material surface treatment wastewater proposed by the present invention includes a wastewater tank, a chemical reactor, a pH sensor, a pH meter, first to third dosing mechanisms and ion exchange equipment. The waste water tank is used to collect the waste water from aluminum material surface treatment. The chemical reactor is connected with the waste water pool to introduce the aluminum material surface treatment waste water. A pH sensor is installed in the chemical reactor. A pH meter is connected to the pH sensor. The first dosing mechanism is used to add acid to the waste water in the chemical reactor until the pH value of the aluminum material surface treatment waste water is adjusted to 2-2.5, so that the metal nickel and aluminum ions in complex state are released. The second dosing mechanism is used to add aluminum to the wastewater in the chemical reactor, so that the ratio of the molar concentration of aluminum ions in the wastewater to the molar concentration of complexed nickel ions is greater than or equal to 1. The third dosing mechanism is used to add alkali to the chemical reactor until the pH value of the wastewater is adjusted to 5.5-6.5, so that the complexing agent and aluminum ions form complexes, and the non-complexed aluminum ions form precipitates. The ion exchange device is connected to the chemical reactor, input the waste water of the chemical reactor, and uses the ion exchange technology to adsorb the nickel ions remaining in the waste water.

In an embodiment of the present invention, the above-mentioned device may include a controller connected to the pH meter and the first to third drug adding mechanisms for controlling the drug adding process.

In one embodiment of the present invention, the chemical reactor is a gap reactor, wherein the pH value of the aluminum material surface treatment wastewater is adjusted to 2-2.5, and then reacted for 20-60 minutes. In another embodiment, the gap reactor reacts for 20-60 minutes after adding aluminum to the waste water.

In an embodiment of the present invention, the first dosing mechanism and the second dosing mechanism are the same dosing mechanism to add acidic anodic oxidation waste liquid containing acid and aluminum for surface treatment of aluminum materials. In this embodiment, the chemical reactor is a gap reactor, and after adding acidic anodic oxidation waste liquid, it reacts for 20-60 minutes.

In an embodiment of the present invention, the above-mentioned device also includes a sludge pump and a filter press, and the sludge pump is connected to the bottom of the chemical reactor and the filter press through a pipeline to transport the sediment to the filter press. After the filter press dehydrates the precipitate, the waste water is returned to the waste water pool.

Compared with the prior art, the present invention has the following significant advantages due to the adoption of the above technical scheme:

1. At the same time, the up-to-standard discharge of aluminum and nickel wastewater and the effective recovery of nickel resources have been realized.

2. The wastewater is pretreated by acidification and network breaking technology, combined with ion exchange technology, to completely solve the problem that aluminum and nickel wastewater cannot meet the standard.

Description of drawings

In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

Fig. 1 is a schematic flow chart of nickel ion separation and recovery of aluminum material surface treatment wastewater according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of a nickel ion separation and recovery device according to an embodiment of the present invention.

Detailed ways

Fig. 1 is a schematic flow chart of nickel ion separation and recovery of aluminum material surface treatment wastewater according to an embodiment of the present invention. Referring to Figure 1, the process is as follows:

Step S1, adding acid to adjust the pH value of the aluminum material surface treatment wastewater to strong acidity, the pH value being 2-2.5, and reacting for a certain period of time. This step utilizes the complexing agents commonly used in aluminum surface treatment, such as citric acid, ammonia water, and fluoride ions, most of which lose or weaken the ability to complex with metal ions under strong acidic conditions, so that the complexed metal nickel and aluminum ions dissociate.

Step S2, adding an appropriate amount of aluminum ions (Al ³⁺ ) to the wastewater to make it reach a certain concentration. In this way, the property that the complexation stability constant of aluminum ions and common complexing agents is greater than that of nickel ions can be used to create conditions for the substitution of aluminum and nickel.

Preferably, the dosage of aluminum ions should be determined according to the complexed nickel ions in the wastewater. It can be determined according to the ratio of molar concentration ratio of aluminum ion to complexed state greater than or equal to 1:1. In actual situations, it is necessary to determine the dosage according to different water qualities. Since the content of the complexing agent is difficult to determine, the simplified approach can be to add aluminum ions according to the molar concentration ratio of aluminum ions and all nickel ions (including complexed and uncomplexed) greater than or equal to 1:1.

In step S3, alkali is added to adjust the waste water to weak acidity, and the pH value is 5.5-6.5. During the transition of wastewater from strong acidity to weak acidity, the complexing agent forms a complex with sufficient aluminum ions, and the remaining non-complexed aluminum ions are due to the difference in solubility product with nickel ions (Al(OH) The solubility product of ₃ is 1.3×10 ^-33 , the solubility product of Ni(OH) ₂ is 2.0×10 ^-15 ), and aluminum hydroxide precipitation will be formed, while nickel ions are still smaller than aluminum ions due to their concentration and complexing ability. The simple Ni ²⁺ state remains in the wastewater.

Step S4, separating the aluminum hydroxide precipitate from the waste water.

In a preferred embodiment, the separated aluminum hydroxide solid can be subjected to additional harmless disposal after dehydration.

Step S5, using ion exchange technology to adsorb nickel ions remaining in the wastewater.

The adsorbed nickel ions in waste water can reach the discharge standard. On the other hand, the ion exchange resin is regenerated after being saturated, and the nickel concentrate obtained from the regeneration is used as the raw material for the production of nickel products to realize resource recycling.

Fig. 2 is a schematic diagram of a nickel ion separation and recovery device according to an embodiment of the present invention. The separation and recovery device includes a wastewater tank 10 , a batch chemical reactor 20 , a filter press 30 , and an ion exchange device 40 . The chemical reactor 20 is provided with a pH sensor 21 and a pH meter 22, as well as first to fourth dosing mechanisms 23-26. A first water pump 51 is provided on the pipeline between the waste water pool 10 and the chemical reactor 20 . A second water pump 52 is provided on the pipeline between the chemical reactor 20 and the ion exchange device 40 . A sludge pump 53 is provided on the pipeline between the chemical reactor 20 and the filter press 30 .

The waste water pool 10 is used to collect waste water for surface treatment of aluminum materials. The chemical reactor is connected to the waste water pool 10 to introduce waste water for surface treatment of aluminum materials. The first dosing mechanism 23 is used for adding acid A to the waste water in the chemical reactor 20 . The second dosing mechanism 24 is used for adding aluminum C to the waste water in the chemical reactor. The third dosing mechanism 25 is used for adding alkali B to the chemical reactor. The fourth dosing mechanism 26 is used to add the polymer flocculant D to the chemical reactor. In the embodiments of the present invention, the acid and the base can be either solid or liquid. Aluminum can be either a soluble aluminum-containing compound or a solution containing aluminum ions.

The pH sensor 21 and the pH meter 22 are used to control the timing of pH adjustment. For example, when acid A is added, until the pH value of the aluminum material surface treatment wastewater is adjusted to 2-2.5. At this pH value, the metal nickel and aluminum ions in the complex state are freed. For another example, when alkali B is added, until the pH value of the wastewater is adjusted to 5.5-6.5. At this pH value, the complexing agent and aluminum ions form a complex, and the uncomplexed aluminum ions form a precipitate, while the nickel ions remain in the wastewater.

In a preferred embodiment, automatic control procedures can be introduced. Specifically, a controller (not shown) is used to connect the pH meter 22 and the first and third dosing mechanisms 23 , 25 , and the dosing process is controlled according to the pH value provided by the pH meter 22 . In one embodiment, the controller may be built into the pH meter 22 .

Nevertheless, in one embodiment, human monitoring instruments can still be used to control the above-mentioned dosing process.

The aluminum dosing amount of the second dosing mechanism 24 can be preset according to the current nickel ion concentration and aluminum ion concentration in the waste liquid, and the concentration ratio of nickel ion and aluminum ion to be achieved. Moreover, considering the fluctuation of the chemical composition in the waste liquid, it is better to maintain a certain margin in the dosage of aluminum.

In another embodiment, the dosing of aluminum by the second dosing mechanism 24 can also be automatically controlled, such as aluminum sulfate solution, and the dosing speed, dosing time, and automatic opening and closing of the valve can be set. Accordingly, the controller is connected to the chemical reactor 20 and the second dosing mechanism 24 .

The chemical reactor 20 is a batch reactor, which can be kept for a certain reaction time when necessary, for example, after adding an acid solution, so as to destroy the complexation of metal ions.

The ion exchange device 40 is connected to the chemical reactor 20, inputs the waste water of the chemical reactor, and uses ion exchange technology to absorb nickel ions remaining in the waste water.

In one embodiment, the device may include a sludge pump 53 and a filter press 30 . The sludge pump 53 is connected to the bottom of the chemical reactor 20 and the filter press 30 through a pipeline, so as to transport the precipitated aluminum hydroxide to the filter press 30 . After the filter press 30 dehydrates the sediment, the waste water is returned to the waste water tank 10 .

Referring to the equipment shown in Figure 2, the separation and recovery process of an embodiment will be described again.

First, the waste water containing nickel ions, aluminum ions and various complexing agents is collected in separate waste water pools 10 . Generally speaking, the pH value of wastewater is greater than 3, the concentration of nickel ions is 20-100mg/L, and the concentration of aluminum ions is about 20-50mg/L. However, these numerical ranges are not fixed, but may vary due to changes in working conditions.

The waste water is input to the chemical reactor 20 . Add acid A to the wastewater to adjust the pH to 2-2.5. And add aluminum C to make the concentration of aluminum ion reach 50-200mg/L. The concentration of aluminum ions can be adjusted depending on the concentration of nickel ions and complexing agent.

After that, react for 20-60 minutes to acidify and destroy the complex, so that the metal nickel becomes a free ion state. It will be understood that the reaction time of 20-60 minutes can also be started before adding aluminum, which is basically equivalent to starting the reaction after adding aluminum.

Then, add base B into the chemical reactor 20 to adjust the pH value to 5.5-6.5. At this time, part of the aluminum ions are complexed with the complexing agent, and the non-complexed aluminum ions are converted into insoluble aluminum hydroxide and fully precipitated. In the pH range of 5.5-6.5, the complexing ability of aluminum ions and complexing agents is stronger than that of nickel ions. When sufficient aluminum ions exist, nickel ions remain in the water in a simple ion state.

The solid aluminum hydroxide precipitated at the bottom of the chemical reactor 20 is sent to the filter press 30 through the sludge pump 53 for dehydration and then harmlessly disposed of. The released wastewater will be returned to the waste water pool 10 for further use.

Thereafter, in the ion exchange equipment 40, the waste water is absorbed and recovered by the sodium-type cation exchange resin, and the nickel ions in the effluent reach the discharge standard of 0.1 mg/L, which can be discharged or reused for production.

The ion exchange resin can be regenerated after being saturated, and the nickel concentrate obtained from the regeneration can be recycled as the raw material for the production of nickel products.

In one embodiment, the ion exchange device 40 can use the device disclosed in Chinese Publication No. CN 101186356A, and its ion exchanger can be separated from the ion exchange device for independent regeneration in another place.

Anodizing is a key process in the surface treatment of aluminum materials. The main components of the anodizing working solution are sulfuric acid and aluminum ions. After a period of use, due to the decrease in sulfuric acid concentration and the increase in aluminum ion concentration, the part must be discharged. The sulfuric acid concentration of the discharge liquid is about For 10%, the concentration of aluminum ions is about 20 g/L. Therefore, in a preferred embodiment, the anodic oxidation waste liquid can be used as the medicament for the acid and aluminum ions required for the above-mentioned acidification and Al-Ni replacement, so as to achieve the purpose of treating waste with waste and saving costs.

In addition, the aluminum hydroxide produced in large quantities in the treatment of aluminum processing wastewater can also be used as the source of aluminum ions required for Al-Ni replacement after simple treatment.

Next, another example of the practical application of the recovery process of the present invention will be given.

The wastewater containing metal nickel ions in the surface treatment wastewater of an aluminum profile processing enterprise was collected in the nickel-containing wastewater pool. Complexing agents (such as citric acid, etc.) that affect nickel ion compliance.

First, waste water enters a batch-type chemical reactor 20 as shown in Figure 2, and adds the anodic oxidation waste liquid A' of this enterprise, which contains aluminum ions 21g/L, and the concentration of sulfuric acid is 20%. Utilize the sulfuric acid in the waste liquid A' to adjust the pH value to 2.0. The pH adjustment is controlled by an online pH meter 22 . At the same time, the aluminum ions in the waste liquid A' also enter the waste water, so that the total amount of aluminum ions contained in the waste water (the sum of the waste water itself and the waste liquid introduced) reaches about 150 mg/L. Acidification and decompression reaction for 60 minutes. Under strongly acidic conditions, complexed nickel is transformed into free nickel ions.

Then, automatically add lye B such as sodium hydroxide under the control of the pH meter to adjust the pH value to 6.5. At this time, some aluminum ions form complexes with the complexing agent prior to nickel ions, and the remaining aluminum ions form aluminum hydroxide precipitates. Since most of the nickel ions are not converted into nickel hydroxide under the condition of pH=6.5, and the complexing agent has been consumed by the aluminum ions, the metal nickel remains in the wastewater in the form of ions.

The polymer flocculant D is added to the waste water, and the solid aluminum hydroxide is precipitated to the bottom of the reactor 20 for 1 hour. Then transport it to the filter press 30, dehydrate and dry, and then send it to a qualified unit for harmless treatment.

In addition, the nickel-containing wastewater in the reactor 20 is sent by the second water pump 52 to the ion exchange device 40 equipped with a cation exchange resin, and the nickel ions are adsorbed on the exchange groups of the resin. The concentration of nickel ions in the effluent after ion exchange is lower than 0.1mg/L, meeting the most stringent discharge standards.

After the ion exchange resin is saturated, a professional unit can be entrusted to regenerate it, and the resin that restores the adsorption function can be reused.

In this application example, the acid and aluminum ions in the production waste liquid are used to realize the acidification and decomplexation and the separation of aluminum and nickel at the same time, and the ion exchange technology is used to achieve the standard discharge of nickel ions while absorbing and recovering nickel ions.

In summary, the embodiment of the nickel ion separation and recovery device for aluminum surface treatment wastewater described in the present invention simultaneously realizes the standard discharge of aluminum and nickel wastewater and the effective recovery of nickel resources. The advantage of these embodiments is that the waste water is pretreated by using the acidification and decollation technology, combined with the ion exchange technology, to completely solve the problem that the aluminum-nickel waste water cannot meet the standard. In addition, in a preferred embodiment, the aluminum-containing waste acid and sludge produced by the enterprise are used as the main agent for the acidification and decomposition treatment to treat waste with waste, which can make the treatment cost low.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection should be defined by the claims.

Claims (7)

1. A nickel ion separation and recovery device for aluminum surface treatment wastewater, comprising: A waste water tank to collect waste water from aluminum surface treatment; A chemical reactor, connected to the waste water tank, to introduce the aluminum material surface treatment waste water; a pH sensor located in the chemical reactor; pH meter, connect the pH sensor; The first dosing mechanism is used to add acid to the wastewater in the chemical reactor until the pH value of the aluminum material surface treatment wastewater is adjusted to 2-2.5, so that the metal nickel and aluminum ions in the complex state are released; The second dosing mechanism is used to add aluminum to the wastewater in the chemical reactor, so that the ratio of the molar concentration of aluminum ions in the wastewater to the molar concentration of complexed nickel ions is greater than or equal to 1; The third dosing mechanism is used to add alkali to the chemical reactor until the pH value of the wastewater is adjusted to 5.5-6.5, so that the complexing agent and aluminum ions form a complex, and the uncomplexed aluminum ions form a precipitate ;as well as The ion exchange equipment is connected with the chemical reactor, input the waste water of the chemical reactor, and uses the ion exchange technology to absorb the nickel ions retained in the waste water. 2. The device according to claim 1, characterized in that it comprises a controller connected to the pH meter and the first to third drug adding mechanisms for controlling the drug adding process. 3. The device according to claim 1, characterized in that, the chemical reactor is a batch reactor, wherein after adjusting the pH value of the aluminum material surface treatment wastewater to 2-2.5, the reaction is carried out for 20-60 minutes. 4. The device according to claim 1, characterized in that the chemical reactor is a batch reactor, wherein after adding aluminum to the waste water, the reaction takes 20-60 minutes. 5. The device according to claim 1, characterized in that, the first dosing mechanism and the second dosing mechanism are the same dosing mechanism to add acidic anodic oxidation waste containing acid and aluminum for surface treatment of aluminum materials liquid. 6. The device according to claim 5, characterized in that the chemical reactor is a batch reactor, and reacts for 20-60 minutes after adding acidic anodic oxidation waste liquid. 7. The device according to claim 1, further comprising a sludge pump and a filter press, the sludge pump is connected to the bottom of the chemical reactor and the filter press through a pipeline, so that the precipitate It is transported to the filter press, and after the filter press dehydrates the precipitate, the waste water is returned to the waste water tank.

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