Method for recycling nickel melting aging solution

Abstract

The invention discloses a method for recycling an electroless nickel aging solution, and belongs to the technical field of electroless nickel wastewater, the electroless nickel aging solution is treated with activated carbon powder and a combined security filter to obtain a pretreatment aging solution, the pretreatment aging solution is added into a fresh water chamber of an electrodialysis system, a sodium sulfate solution is added into a concentrated water chamber and an electrode water chamber respectively, and the electrodialysis system is used for electrodialysis; collecting liquid in a fresh water chamber after electrodialysis treatment to obtain fresh water, and collecting liquid in a concentrated water chamber to obtain concentrated water; the nickel concentration, the hypophosphorous acid concentration and the phosphorous acid concentration in the fresh water and the concentrated water are detected respectively, then a nickel reagent and a hypophosphorous acid reagent are supplemented into the fresh water to obtain regenerated and recycled aging liquid which is recycled as tank liquid, and the hypophosphorous acid in the concentrated water is recycled; the regenerated and recycled aging solution obtained through treatment is put into use again as a bath solution, the activity of the regenerated and recycled aging solution reaches 65% or above of the activity of a cylinder opening agent, the use amount of a nickel agent and a hypophosphorous acid agent can be reduced, the scrap amount of the nickel bath solution can be reduced, and cost reduction is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of nickel-plating wastewater, and in particular relates to a method for recycling aged nickel-plating liquid. Background Art

[0002] Chemical nickel plating actually deposits NiP (nickel-phosphorus alloy), but because the nickel content in the coating is relatively large, it is customarily called chemical nickel plating. Chemical nickel plating is a method of obtaining a coating by self-catalytic reduction deposition on the surface of an activated workpiece using a reducing agent without applying an external current. The coating is deposited on the surface of the activated workpiece, and due to the self-catalytic ability of nickel, its reduction process will continue automatically until the part is taken out of the plating tank.

[0003] At present, the application scope of chemical nickel plating in my country is constantly expanding, from the initial simple lining of nuclear industry and oil industry storage to petrochemical, aviation, aerospace, textile, papermaking, printing, food, automobile and machinery and other fields. However, the problem of aging liquid treatment has not attracted enough attention.

[0004] Nickel is a precious metal and a non-renewable resource. The nickel solution and hypophosphorous acid solution in the nickel bath are relatively expensive. The price of the tank bath is 35-40 yuan / L, and the price of the self-prepared bath is also 30-35 yuan / L. The cost of the bath has become one of the important factors that hinder the development of businesses in the surface treatment industry. In addition, the nickel bath undergoes multiple cycles of chemical plating, resulting in the accumulation of phosphorous acid and sulfate. The more phosphorous acid accumulates, the greater the impact on the quality of the plated parts, resulting in a decrease in the bonding strength of the plated parts (peeling), a decrease in the plating speed, and the occurrence of negative phenomena such as missed plating and pinholes. Therefore, the bath needs to be scrapped after a certain period of use.

[0005] The treatment cost of nickel aging solution is very high. According to research, the treatment cost of one cubic meter of nickel bath solution is 3,000-4,000 yuan. Since nickel exists in a complex form, ordinary dosing precipitation has poor effect, and hypophosphorous acid is also difficult to treat using conventional chemical precipitation methods. It needs to add strong oxidants for pretreatment, which has high treatment costs and wastes resources. Summary of the invention

[0006] The purpose of the present invention is to provide a method for recycling nickel plating aging liquid, by subjecting the nickel plating aging liquid to electrodialysis treatment, collecting fresh water to prepare regenerated and reused aging liquid, thereby reducing the treatment cost of the nickel plating aging liquid and the production cost of chemical nickel plating.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A method for recycling nickel-plating aging liquid comprises the following steps:

[0009] Step 1: Add the nickel aging solution and activated carbon powder into a stirring tank, stir at a speed of 100-300r / min for 0.5-1h, and let it stand for 20-24h to adsorb impurities and surfactants in the nickel aging solution, and then filter the obtained mixed solution through a combined security filter for 2-3 times to filter out the activated carbon powder in the mixed solution, and obtain the pre-treated aging solution after completing the pre-treatment operation;

[0010] Step 2: Add the pre-treated aged liquid to the fresh water chamber of the electrodialysis system, add sodium sulfate solutions of different concentrations to the concentrated water chamber and the extreme water chamber respectively, start the electrodialysis system, perform electrodialysis at an operating voltage of 60V and an operating current of 70A, stop the reaction when the conductivity of the concentrated water chamber reaches 75-80ms / cm, collect the liquid in the fresh water chamber to obtain fresh water, and collect the liquid in the concentrated water chamber to obtain concentrated water;

[0011] Step 3: respectively detecting the nickel concentration, hypophosphorous acid concentration and phosphorous acid concentration in the fresh water and concentrated water, and then adding nickel reagent and hypophosphorous acid reagent to the fresh water to obtain the regenerated reused aging liquid, which is reused as the tank liquid;

[0012] Step 4: Add calcium salt to the concentrated water, stir at 60-65°C for 4-5 hours, then let it stand for 10-12 hours, remove calcium phosphite by calcium precipitation, filter the supernatant, adjust the pH value of the filtrate to 7-8 with sulfuric acid solution, transfer it to a resin tank for calcium removal, evaporate and concentrate, and obtain hypophosphorous acid recovery liquid, which can be reused as hypophosphorous acid.

[0013] Furthermore, in step 1, the usage ratio of activated carbon powder and nickel aging solution is 1-2g:1L.

[0014] Furthermore, in step 1, the combined security filter is composed of a first security filter with a filtration accuracy of 5 μm and a second security filter with a filtration accuracy of 1 μm.

[0015] Furthermore, in step 2, the concentration of the sodium sulfate solution added to the concentrated water chamber is 5-20 g / L, and the concentration of the sodium sulfate solution added to the extreme water chamber is 20 g / L.

[0016] Furthermore, the method for detecting the nickel concentration in step three is the ICP method, and the method for detecting the hypophosphorous acid concentration and the phosphorous acid concentration is the iodine titration method.

[0017] Furthermore, in step 3, the nickel concentration of the regenerated and reused aging solution is 5.6 g / L, and the hypophosphorous acid concentration is 25 g / L.

[0018] Furthermore, in step 4, the calcium salt is calcium oxide or calcium hydroxide.

[0019] Beneficial effects of the present invention:

[0020] The method for recycling nickel-plating aged liquid of the present invention reuses the treated regenerated aged liquid as tank liquid, and the activity of the regenerated aged liquid reaches more than 65% of the activity of the cylinder opening agent, which can reduce the usage of nickel reagent and hypophosphorous acid reagent, and also reduce the scrapping amount of nickel-plating tank liquid, which helps to reduce costs.

[0021] The pre-treatment aging liquid treated with activated carbon can remove impurities and surfactants in the nickel aging liquid, which is convenient for electrodialysis treatment; the pre-treatment aging liquid is located in the fresh water chamber, and the concentrated water chamber uses sodium sulfate solution. With the progress of electrodialysis treatment, the phosphorous acid and hypophosphorous acid in the pre-treatment aging liquid are transferred to the concentrated water chamber. Nickel transfers a very small amount due to the complex state, which helps to remove phosphorous acid. The treated fresh water can be put back into use after adding hypophosphorous acid reagent and nickel reagent to the appropriate concentration; the concentrated water is treated with calcium salt to remove phosphite precipitation, and the hypophosphorous acid can be concentrated and recovered, which helps to increase the recycling rate of the nickel aging liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below in conjunction with the accompanying drawings.

[0023] Figure 1 The present invention is a flow chart of the method for recycling nickel-plated aging liquid. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0025] Example 1: This example provides a method for recycling nickel aging solution. Figure 1 , specifically including the following steps:

[0026] S1: Add nickel chloride aging liquid and activated carbon powder into a stirring tank at a dosage ratio of 1L:1g, stir at a speed of 100r / min for 0.5h, let it stand for 20h to adsorb impurities and surfactants in the nickel chloride aging liquid, and then filter the obtained mixed liquid twice through a combined security filter to filter out the activated carbon powder in the mixed liquid. After completing the pretreatment operation, a pretreated aging liquid is obtained; wherein the combined security filter includes a first security filter with a filtration accuracy of 5μm and a second security filter with a filtration accuracy of 1μm.

[0027] S2: Add 71L of pre-treated aging liquid to the fresh water chamber of the electrodialysis system, add 61L of 5g / L sodium sulfate solution to the concentrated water chamber, add 25L of 20g / L sodium sulfate solution to the extreme water chamber, start the electrodialysis system to purify the pre-treated aging liquid, the operating voltage is 60V, the operating current is 70A, monitor the conductivity of the concentrated water chamber to reach 75ms / cm, stop the reaction, collect the liquid in the fresh water chamber to obtain fresh water, and collect the liquid in the concentrated water chamber to obtain concentrated water.

[0028] S3: The nickel concentration in fresh water and concentrated water was detected by ICP method, and the hypophosphorous acid concentration and phosphorous acid concentration in fresh water and concentrated water were detected by iodine titration method. The results are shown in Table 1:

[0029] Table 1

[0030]

[0031]

[0032] S4: Add nickel reagent and hypophosphorous acid reagent to the fresh water, adjust the nickel concentration to 5.6g / L and the hypophosphorous acid concentration to 25g / L, and obtain the regenerated reused aging liquid, which is reused as the tank liquid.

[0033] S5: According to Ca 2+ and HPO 3 2- Calcium oxide was added to concentrated water at a molar mass ratio of 2:1, stirred at 60°C for 4 hours, and then allowed to stand for 10 hours. Calcium phosphite was removed by calcium precipitation. The pH value of the supernatant was detected to be greater than 14, accompanied by a strong ammonia smell, and the supernatant was light blue; the supernatant was filtered, and the filtrate was adjusted to pH 7 with sulfuric acid solution, the ammonia smell and light blue color disappeared, and then transferred to a resin tank for calcium removal, evaporated and concentrated, and hypophosphorous acid recovery liquid was obtained, which can be reused as hypophosphorous acid. After calculation, the removal rate of phosphorous acid in the hypophosphorous acid recovery liquid was greater than 99%, the removal rate of nickel was greater than 85%, and the adsorption rate of calcium ions was greater than 98%.

[0034] Example 2: This example provides a method for recycling nickel aging solution. Figure 1 , specifically including the following steps:

[0035] S1: Add nickel chloride aging liquid and activated carbon powder into a stirring tank at a dosage ratio of 1L:1.5g, stir at a speed of 200r / min for 0.8h, let it stand for 22h to adsorb impurities and surfactants in the nickel chloride aging liquid, and then filter the obtained mixed liquid twice through a combined security filter to filter out the activated carbon powder in the mixed liquid. After completing the pretreatment operation, a pretreated aging liquid is obtained; wherein the combined security filter includes a first security filter with a filtration accuracy of 5μm and a second security filter with a filtration accuracy of 1μm.

[0036] S2: Add 75L of pretreated aging liquid to the fresh water chamber of the electrodialysis system, add 60L of 10g / L sodium sulfate solution to the concentrated water chamber, add 25L of 20g / L sodium sulfate solution to the extreme water chamber, the operating voltage is 60V, the operating current is 70A, monitor the conductivity of the concentrated water chamber when it reaches 77.5ms / cm, stop the reaction, collect the liquid in the concentrated water chamber to obtain concentrated water.

[0037] S3: The nickel concentration in fresh water and concentrated water was detected by ICP method, and the hypophosphorous acid concentration and phosphorous acid concentration in fresh water and concentrated water were detected by iodine titration method. The results are shown in Table 2:

[0038] Table 2

[0039]

[0040] S4: Add nickel reagent and hypophosphorous acid reagent to the fresh water, adjust the nickel concentration to 5.6g / L and the hypophosphorous acid concentration to 25g / L, and obtain the regenerated reused aging liquid, which is reused as the tank liquid.

[0041] S5: According to Ca 2+ and HPO 3 2- Calcium hydroxide was added to concentrated water at a molar mass ratio of 2:1, stirred at 62°C for 4.5 hours, and then allowed to stand for 11 hours. Calcium phosphite was removed by calcium precipitation. The pH value of the supernatant was detected to be greater than 14, accompanied by a strong ammonia smell, and the supernatant was light blue; the supernatant was filtered, and the filtrate was adjusted to pH 7.5 with sulfuric acid solution. The ammonia smell and light blue color disappeared, and then transferred to a resin tank for calcium removal, evaporated and concentrated, and hypophosphorous acid recovery liquid was obtained, which can be reused as hypophosphorous acid. After calculation, the removal rate of phosphorous acid in the hypophosphorous acid recovery liquid was greater than 99%, the removal rate of nickel was greater than 85%, and the adsorption rate of calcium ions was greater than 98%.

[0042] Example 3: This example provides a method for recycling nickel aging solution. Figure 1 , specifically including the following steps:

[0043] S1: Add nickel chloride aging solution and activated carbon powder into a stirring tank at a dosage ratio of 1L:2g, stir at a speed of 300r / min for 1h, let it stand for 24h to adsorb impurities and surfactants in the nickel chloride aging solution, and then filter the obtained mixed solution through a combined security filter for 3 times to filter out the activated carbon powder in the mixed solution. After completing the pretreatment operation, a pretreated aging solution is obtained; wherein the combined security filter includes a first security filter with a filtration accuracy of 5μm and a second security filter with a filtration accuracy of 1μm.

[0044] S2: Add 73L of pretreated aging liquid to the fresh water chamber of the electrodialysis system, add 60L of 20g / L sodium sulfate solution to the concentrated water chamber, add 25L of 20g / L sodium sulfate solution to the extreme water chamber, the operating voltage is 60V, the operating current is 70A, monitor the conductivity of the concentrated water chamber when it reaches 80ms / cm, stop the reaction, collect the liquid in the fresh water chamber to obtain fresh water, and collect the liquid in the concentrated water chamber to obtain concentrated water.

[0045] S3: The nickel concentration in fresh water and concentrated water was detected by ICP method, and the hypophosphorous acid concentration and phosphorous acid concentration in fresh water and concentrated water were detected by iodine titration method. The results are shown in Table 3:

[0046] Table 3

[0047]

[0048] S4: Add nickel reagent and hypophosphorous acid reagent to the fresh water, adjust the nickel concentration to 5.6g / L and the hypophosphorous acid concentration to 25g / L, and obtain the regenerated reused aging liquid, which is reused as the tank liquid.

[0049] S5: According to Ca 2+ and HPO 3 2- Calcium hydroxide was added to concentrated water at a molar mass ratio of 2:1, stirred at 65°C for 5 hours, and then allowed to stand for 12 hours. Calcium phosphite was removed by calcium precipitation. The pH value of the supernatant was detected to be greater than 14, accompanied by a strong ammonia smell, and the supernatant was light blue; the supernatant was filtered, and the filtrate was adjusted to pH 8 with sulfuric acid solution, the ammonia smell and light blue color disappeared, and then transferred to a resin tank for calcium removal, evaporated and concentrated, and hypophosphorous acid recovery liquid was obtained, which can be reused as hypophosphorous acid. After calculation, the removal rate of phosphorous acid in the hypophosphorous acid recovery liquid was greater than 99%, the removal rate of nickel was greater than 85%, and the adsorption rate of calcium ions was greater than 98%.

[0050] Application example: Testing the activity of the recycled tank liquid in Examples 1 to 3:

[0051] The engineering parts treated by the water washing-zinc precipitation-water washing process were used as samples, and the chemical nickel plating test was carried out using the recycled aging solution recovered in the embodiment as the bath solution, and the tank opening agent was used as the bath solution for reference, which was recorded as the control group. The nickel concentration in the nickel agent used in the embodiment and the application example was 90g / L, and the hypophosphorous acid concentration in the hypophosphorous acid agent was 150g / L. The tank opening agent, nickel agent and hypophosphorous acid agent were all purchased from Guangdong Bigley Technology Co., Ltd.

[0052] Add the same volume of bath solution to a 200L nickel bath, heat the bath solution to 85°C, and then place the samples in the corresponding nickel bath for chemical nickel plating. Periodically detect the nickel concentration in the bath solution, add nickel agent and hypophosphorous acid agent according to the concentration, calculate based on 1h of chemical nickel plating, and mark each time 12.5L of nickel agent is added as a cycle. Record the addition cycle of chemical nickel plating with different bath solutions, and calculate the activity of the regenerated and reused aging solution. The activity of the regenerated and reused aging solution = the addition cycle of the regenerated and reused aging solution / the addition cycle of the cylinder opening agent × 100%. The results are shown in Table 4:

[0053] Table 4

[0054] project Example 1 Example 2 Example 3 Control group cycle 3 3.2 3 4.5 active(%) 66.7 68.9 66.7 /

[0055] It can be seen from Table 4 that the activity of the regenerated and reused aging liquid in the embodiment reaches more than 65% of the cylinder opening agent. Using the regenerated and reused aging liquid as the tank liquid can not only reduce the use of nickel and subphosphorus agents, but also reduce the amount of nickel bath liquid scrapped, killing two birds with one stone.

[0056] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0057] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for recycling nickel aging solution, characterized in that: The steps include: Step 1: Add the pretreated aged liquid obtained after the pretreatment operation of the nickel chloride aged liquid into the fresh water chamber of the electrodialysis system, add sodium sulfate solution into the concentrated water chamber and the extreme water chamber respectively, perform electrodialysis at an operating voltage of 60V and an operating current of 70A, stop the reaction when the conductivity of the concentrated water chamber reaches 75-80ms / cm, collect the liquid in the fresh water chamber to obtain fresh water, and collect the liquid in the concentrated water chamber to obtain concentrated water; Step 2: respectively detecting the nickel concentration, hypophosphorous acid concentration and phosphorous acid concentration in the fresh water and concentrated water, and then adding nickel reagent and hypophosphorous acid reagent to the fresh water to obtain the regenerated reused aging liquid, which is reused as the tank liquid; Step 3: Add calcium salt to concentrated water, stir at 60-65°C for 4-5h, then let stand for 10-12h, filter the supernatant, adjust the pH value of the filtrate to 7-8 with sulfuric acid solution, transfer to a resin tank for calcium removal, evaporate and concentrate to obtain hypophosphorous acid recovery liquid, which is reused as hypophosphorous acid.

2. The method for recycling nickel-plating aged liquid according to claim 1, characterized in that: The preprocessing operations in step 1 are as follows: Add the nickel aging solution and activated carbon powder into a stirring tank, stir at a speed of 100-300r / min for 0.5-1h, let it stand for 20-24h, and filter it through a combined security filter 2-3 times to complete the pretreatment operation and obtain the pretreated aging solution.

3. The method for recycling nickel-plating aged solution according to claim 2, characterized in that: The usage ratio of the activated carbon powder and the nickel aging solution is 1-2g:1L.

4. The method for recycling nickel-plating aged solution according to claim 2, characterized in that: The combined safety filter is composed of a first safety filter with a filtering accuracy of 5 μm and a second safety filter with a filtering accuracy of 1 μm.

5. The method for recycling nickel-plating aged solution according to claim 1, characterized in that: In step 1, the concentration of the sodium sulfate solution added to the concentrated water chamber is 5-20 g / L, and the concentration of the sodium sulfate solution added to the extreme water chamber is 20 g / L.

6. The method for recycling nickel-plating aged solution according to claim 1, characterized in that: The method for detecting the nickel concentration in step 2 is the ICP method, and the method for detecting the hypophosphorous acid concentration and the phosphorous acid concentration is the iodine titration method.

7. The method for recycling nickel-plating aged solution according to claim 1, characterized in that: The nickel concentration of the regenerated and reused aging solution in step 2 is 5.6 g / L, and the hypophosphorous acid concentration is 25 g / L.

8. The method for recycling nickel-plating aged solution according to claim 1, characterized in that: The calcium salt in step 3 is calcium oxide or calcium hydroxide.

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