Process for treating nickel wastewater containing nickel acetate cleaning water and nickel acetate concentrated water

Abstract

The invention discloses a process for treating nickel wastewater containing nickel acetate cleaning water and nickel acetate concentrated water, which comprises the following steps: S1, filtering nickel wastewater, S2, carrying out primary concentration treatment, S3, carrying out secondary concentration treatment, S4, treating by a sodium metaaluminate method, S5, carrying out collaborative filtration treatment, and S6, discharging RO (Reverse Osmosis) produced water up to the standard. The method comprises the following steps: primarily enriching nickel ions by adopting primary nickel concentration treatment and secondary nickel concentration treatment, adding a sodium metaaluminate solution into a mixed solution, enabling the pH value of the mixed solution to be 8-12, enabling the nickel ions to react with hydroxyl ions to generate a nickel hydroxide precipitate, adding a sulfuric acid solution to adjust the pH value of the mixed solution back to 6.5-7.5, hydrolyzing sodium metaaluminate to generate an aluminum hydroxide precipitate, and carrying out secondary nickel concentration treatment on the aluminum hydroxide precipitate; aluminum hydroxide adsorbs nickel hydroxide to form a composite precipitate, aluminum ions and nickel ions are subjected to a competitive complexation reaction, and a flocculating agent is added into a mixed solution to form a flocculent precipitate, so that the reaction time is short, the nickel content in the nickel sludge can be greatly increased, the treatment period can be shortened, and the operation cost can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of nickel wastewater treatment technology, in particular to a nickel wastewater treatment process containing nickel acetate cleaning water and nickel acetate concentrated water. Background Art

[0002] With the rapid development of industry, nickel is increasingly used in various fields such as electroplating, metallurgy, and chemical industry, resulting in an increasing discharge of nickel-containing wastewater. Nickel is a potentially toxic heavy metal element. Its excessive discharge can cause serious pollution to water bodies, soil and the ecological environment, and pose a threat to human health through accumulation in the food chain.

[0003] At present, the treatment technology for nickel acetate cleaning water and nickel acetate concentrated water adopts micro-electrolysis / UV photolysis + Fenton process to treat nickel-containing wastewater. However, this method has the disadvantages of long reaction time, high operating cost and low nickel content in nickel sludge. In addition, there is a special treatment method. The first step: nickel acetate cleaning water is collected through the pipeline and enters the collection pool. The nickel-containing wastewater is pumped into the T27 ion concentration system for preliminary separation through the lifting pump. The fresh water separated by the T27 ion concentration system is used as the raw water of the T40 ion concentration system, and the T27 concentrated water is used as the raw water of the T40 ion concentration system. The raw water is from the three-stage T100 concentration system. In the second step, the water produced by the T40 ion concentration system enters the RO membrane filtration system. The RO produced water meets the discharge standards, and the concentrated water returns to the first-stage T27 ion concentration system for further concentration. In the third step, the three-stage T100 ion concentration system has two water streams: nickel acetate concentrated water and first-stage T27 concentrated water. The produced water returns to the sodium acetate cleaning water, and the concentrated water enters the electrolysis system after impurities are removed. Although this special treatment method can ultimately achieve a nickel purity of 95%-99%, it has the disadvantages of high power consumption and high operating costs of the electrolysis system. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technical solutions, the present invention provides a nickel wastewater treatment process containing nickel acetate cleaning water and nickel acetate concentrated water, which can effectively solve the technical problems raised by the background technology.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a nickel wastewater treatment process containing nickel acetate cleaning water and nickel acetate concentrated water, comprising the following steps:

[0006] Step S1, collecting nickel wastewater into a collection tank, transporting the nickel wastewater to a filter for filtration, and obtaining a liquid to be treated and large particle impurities;

[0007] Step S2: transporting the liquid to be treated to a primary concentration system for preliminary separation to obtain primary low-nickel water and primary concentrated nickel water;

[0008] Step S3: transporting the primary low-nickel water to a secondary concentration system for further separation to obtain secondary low-nickel water and secondary concentrated nickel water, and transporting the secondary low-nickel water to a water production pool;

[0009] Step S4: mixing the first-level concentrated nickel water and the second-level concentrated nickel water to obtain a mixed solution, adding a sodium aluminate solution to the mixed solution, the pH value of the mixed solution is 8-12, nickel ions react with hydroxide ions to generate nickel hydroxide precipitate, adding a sulfuric acid solution to adjust the pH value of the mixed solution to 6.5-7.5, hydrolyzing the sodium aluminate to generate aluminum hydroxide precipitate, the aluminum hydroxide adsorbs the nickel hydroxide to form a composite precipitate, the aluminum ions and the nickel ions undergo a competitive complexation reaction, and adding a flocculant to the mixed solution to form a flocculated precipitate;

[0010] Step S5: transporting the precipitated sludge obtained in step S4 to a filter press for squeezing, transporting the treated liquid obtained in step S4 to a water production pool, mixing the secondary low-nickel water and the treated liquid and transporting them together to an RO membrane filtration system to obtain RO produced water and RO concentrated water;

[0011] Step S6: The RO concentrated water is transported to the collection tank in step S1, and steps S1-5 are repeated until the RO produced water meets the discharge standards.

[0012] Furthermore, in step S1, nickel acetate cleaning water and nickel acetate concentrated water are mixed to obtain nickel wastewater.

[0013] Furthermore, in step S1, the security filter is a cotton core filter or a bag filter.

[0014] Furthermore, the primary concentration system in step S2 uses a Ni / CuT27 membrane, the operating range of which is between ultrafiltration and nanofiltration, with a monovalent ion retention rate of ≤1% and a divalent ion retention capacity of between 70% and 90%.

[0015] Furthermore, the secondary concentration system in step S3 uses a Ni / CuT40 membrane, the operating range of which is between nanofiltration and reverse osmosis, with a monovalent ion retention rate of 20% to 70% and a divalent ion retention capacity of 50% to 98%.

[0016] Furthermore, in step S4, the mass ratio of aluminum ions in the sodium metaaluminate solution to nickel ions in the wastewater is 50-250:1, and the pH value of the mixed solution is increased to 8-12.

[0017] Furthermore, the RO membrane filtration system in step S5 adopts a medium-pressure high-salt brackish water membrane.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This technical solution uses a primary nickel concentration treatment and a secondary nickel concentration treatment to preliminarily enrich nickel ions. After mixing the primary concentrated nickel water and the secondary concentrated nickel water, sodium aluminate solution is added to the mixed solution. The pH value of the mixed solution is 8-12. Nickel ions react with hydroxide ions to form nickel hydroxide precipitate. Sulfuric acid solution is added to adjust the pH value of the mixed solution to 6.5-7.5. Sodium aluminate is hydrolyzed to form aluminum hydroxide precipitate. Aluminum hydroxide adsorbs nickel hydroxide to form a composite precipitate. Aluminum ions and nickel ions undergo a competitive complexation reaction. A flocculant is added to the mixed solution to form a flocculated precipitate. The reaction time is fast and the nickel content in the nickel sludge can be greatly increased. In addition, the secondary low-nickel water and the treated liquid are mixed and transported together to the RO membrane filtration system for deep treatment. This collaborative treatment method can shorten the treatment cycle and reduce operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention provides a flow chart of a nickel wastewater treatment process containing nickel acetate cleaning water and nickel acetate concentrated water. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] like Figure 1 As shown, the present invention provides a nickel wastewater treatment process containing nickel acetate cleaning water and nickel acetate concentrated water, comprising the following steps:

[0023] Step S1: Filtering nickel wastewater

[0024] The nickel acetate cleaning water and the nickel acetate concentrated water are mixed to obtain nickel wastewater, the nickel wastewater is collected in a collection pool, and the nickel wastewater is transported to a filter for filtration to obtain a liquid to be treated and large particle impurities. The safety filter is a cotton core filter or a bag filter;

[0025] Step S2: Primary concentration treatment

[0026] The liquid to be treated is transported to a primary concentration system for preliminary separation. The primary concentration system uses a Ni / CuT27 membrane, model YX-NiT27-15. The operating range of the Ni / CuT27 membrane is between ultrafiltration and nanofiltration, with a monovalent ion retention rate of ≤1% and a divalent ion retention capacity of between 70% and 90%. The nickel ions in the nickel wastewater are concentrated by utilizing the membrane's selective filtration characteristics. The nickel wastewater is then separated into primary low-nickel water and primary concentrated nickel water after concentration treatment.

[0027] Step S3: Secondary concentration treatment

[0028] The primary low-nickel water is transported to the secondary concentration system for further separation. The secondary concentration system uses a Ni / CuT40 membrane, model YX-NiT40-15. The operating range of the Ni / CuT40 membrane is between nanofiltration and reverse osmosis, with a monovalent ion retention rate of 20% to 70% and a divalent ion retention capacity of 50% to 98%. The nickel ions in the primary low-nickel water are concentrated by utilizing the membrane's selective filtration characteristics. The primary low-nickel water is concentrated to separate secondary low-nickel water and secondary concentrated nickel water, and the secondary low-nickel water is transported to the water production pool;

[0029] Step S4: Sodium aluminate treatment

[0030] Mixing first-grade concentrated nickel water and second-grade concentrated nickel water to obtain a mixed solution, adding sodium metaaluminate solution to the mixed solution, wherein the mass ratio of aluminum ions in the sodium metaaluminate solution to nickel ions in the wastewater is 50-250:1, and raising the pH value of the mixed solution to 8-12, allowing nickel ions to react with hydroxide ions to generate nickel hydroxide precipitate, adding sulfuric acid solution to adjust the pH value of the mixed solution to 6.5-7.5, hydrolyzing the sodium metaaluminate to generate aluminum hydroxide precipitate, and adsorbing the nickel hydroxide to form a composite precipitate, causing a competitive complexation reaction between the aluminum ions and the nickel ions, and adding a flocculant to the mixed solution to form a flocculated precipitate;

[0031] Step S5: Collaborative filtering processing

[0032] The precipitated sludge obtained in step S4 is conveyed to a filter press for squeezing. The treated liquid obtained in step S4 is conveyed to a water production pool. The secondary low-nickel water and the treated liquid are mixed and conveyed together to an RO membrane filtration system. The RO membrane filtration system uses a medium-pressure high-salt brackish water membrane, model YIME-MP-BW-8040-(FR). The nickel ions in the mixed water are concentrated by utilizing the membrane's selective filtration characteristics. The mixed water is then concentrated to obtain RO produced water and RO concentrated water.

[0033] Step S6: RO produced water meets discharge standards

[0034] The RO concentrated water is transported to the collection tank in step S1, and steps S1-5 are repeated until the RO produced water meets the discharge standards.

[0035] The following is a table of test conditions and test data for nickel concentration (mg / L), conductivity (mS / cm), and pH value in a nickel wastewater treatment process containing nickel acetate cleaning water and nickel acetate concentrated water according to the present invention;

[0036]

[0037] Compared with traditional technology: This technical solution adopts primary nickel concentration treatment and secondary nickel concentration treatment to preliminarily enrich nickel ions. After mixing the primary concentrated nickel water and the secondary concentrated nickel water, sodium aluminate solution is added to the mixed solution. The pH value of the mixed solution is 8-12. Nickel ions react with hydroxide ions to form nickel hydroxide precipitate. Sulfuric acid solution is added to adjust the pH value of the mixed solution to 6.5-7.5. Sodium aluminate is hydrolyzed to form aluminum hydroxide precipitate. Aluminum hydroxide adsorbs nickel hydroxide to form a composite precipitate. Aluminum ions and nickel ions undergo a competitive complexation reaction. Flocculant is added to the mixed solution to form a flocculated precipitate. The reaction time is fast and the nickel content in the nickel sludge can be greatly increased. In addition, the secondary low-nickel water and the treated liquid are mixed and transported together to the RO membrane filtration system for deep treatment. This collaborative treatment method can shorten the treatment cycle and reduce operating costs.

[0038] 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 invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the 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 included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A nickel wastewater treatment process containing nickel acetate cleaning water and nickel acetate concentrated water, characterized in that, The following steps are involved: Step S1, collecting nickel wastewater into a collection tank, transporting the nickel wastewater to a filter for filtration, and obtaining a liquid to be treated and large particle impurities; Step S2: transporting the liquid to be treated to a primary concentration system for preliminary separation to obtain primary low-nickel water and primary concentrated nickel water; Step S3: transporting the primary low-nickel water to a secondary concentration system for further separation to obtain secondary low-nickel water and secondary concentrated nickel water, and transporting the secondary low-nickel water to a water production pool; Step S4: mixing the first-level concentrated nickel water and the second-level concentrated nickel water to obtain a mixed solution, adding a sodium aluminate solution to the mixed solution, the pH value of the mixed solution is 8-12, nickel ions react with hydroxide ions to generate nickel hydroxide precipitate, adding a sulfuric acid solution to adjust the pH value of the mixed solution to 6.5-7.5, hydrolyzing the sodium aluminate to generate aluminum hydroxide precipitate, the aluminum hydroxide adsorbs the nickel hydroxide to form a composite precipitate, the aluminum ions and the nickel ions undergo a competitive complexation reaction, and adding a flocculant to the mixed solution to form a flocculated precipitate; Step S5: transporting the precipitated sludge obtained in step S4 to a filter press for squeezing, transporting the treated liquid obtained in step S4 to a water production pool, mixing the secondary low-nickel water and the treated liquid and transporting them together to an RO membrane filtration system to obtain RO produced water and RO concentrated water; Step S6: The RO concentrated water is transported to the collection tank in step S1, and steps S1-5 are repeated until the RO produced water meets the discharge standards.

2. A nickel wastewater treatment process containing nickel acetate cleaning water and nickel acetate concentrated water according to claim 1, characterized in that, In the step S1, nickel acetate cleaning water and nickel acetate concentrated water are mixed to obtain nickel wastewater.

3. A nickel wastewater treatment process containing nickel acetate cleaning water and nickel acetate concentrated water according to claim 1, characterized in that, In step S1, the security filter is a cotton core filter or a bag filter.

4. A nickel wastewater treatment process containing nickel acetate cleaning water and nickel acetate concentrated water according to claim 1, characterized in that, The primary concentration system in step S2 uses a Ni / CuT27 membrane. The operating range of the Ni / CuT27 membrane is between ultrafiltration and nanofiltration, with a monovalent ion retention rate of ≤1% and a divalent ion retention capacity of between 70% and 90%.

5. A nickel wastewater treatment process containing nickel acetate cleaning water and nickel acetate concentrated water according to claim 1, characterized in that, The secondary concentration system in step S3 uses a Ni / CuT40 membrane. The operating range of the Ni / CuT40 membrane is between nanofiltration and reverse osmosis, with a monovalent ion retention rate of 20% to 70% and a divalent ion retention capacity of 50% to 98%.

6. A nickel wastewater treatment process containing nickel acetate cleaning water and nickel acetate concentrated water according to claim 1, characterized in that, In step S4, the mass ratio of aluminum ions in the sodium metaaluminate solution to nickel ions in the wastewater is 50-250:1, and the pH value of the mixed solution is increased to 8-12.

7. A nickel wastewater treatment process containing nickel acetate cleaning water and nickel acetate concentrated water according to claim 1, characterized in that, The RO membrane filtration system in step S5 uses a medium-pressure high-salt brackish water membrane.

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