Electroless plating waste liquid treatment method and electroless plating waste liquid treatment system

Abstract

To provide a waste liquid treatment method and waste liquid treatment system, capable of efficiently performing a reaction to substantially reduce heating energy and collecting all useful components (a nickel component, a hypophosphorous acid component and an organic component) included in waste liquid and generated hydrogen to effectively use them.SOLUTION: An electroless plating waste liquid treatment method comprises: a reaction step of reacting electroless plating waste fluid including a nickel component and hypophosphorous acid at a temperature of 18°C or more and less than 50°C in an alkaline environment using iron powder as a catalyst to generate a phosphorous acid and hydrogen; a hydrogen collection step of collecting the hydrogen generated in the reaction step; a nickel coated iron powder collection step of collecting nickel coated iron powder included in a reaction solution obtained in the reaction step; and a phosphorous acid calcium collection step of separating and dehydrating a phosphorous acid calcium salt obtained by adding a calcium material for generating the phosphorous acid calcium salt to generate the phosphorous acid calcium salt to collect phosphorous acid calcium.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and system for treating electroless plating waste liquid. [Background technology]

[0002] Currently, electroless plating technology is used in a variety of fields, from decorative plated products to the manufacture of electronic components such as magnetic disks and magnetic tapes, and in addition to the traditionally widely used nickel, nickel-cobalt alloys and other plating metals are also being used.

[0003] In electroless plating, the substrate to be plated is generally immersed in a plating solution prepared in advance and allowed to react for a predetermined period of time. However, even if the plating bath and process conditions are appropriately controlled during the treatment stage, an increase in oxidation products during the reaction is unavoidable, making it difficult to reuse the treatment solution that has been used.

[0004] From the above, after a certain plating reaction, the bath solution contains Ni 2+ Although it contains a large amount of plating metal ions such as phosphate and reducing components such as sodium hypophosphite, in many cases it is disposed of as waste electroless plating solution.

[0005] However, due to the need to prevent pollution and purify the environment, ocean dumping is prohibited, and while efforts have been made to recover and reuse the active ingredients (nickel and phosphorus) contained in the wastewater, the current situation is that these efforts are not sufficient.

[0006] Methods for treating electroless plating wastewater include those described in Patent Documents 1 and 2 below. Patent Document 1 (1) describes nickel as a catalyst but not iron, (2) describes a reaction temperature of 50 to 90°C, and in particular a high temperature of 80°C in the examples, (3) oxidizes phosphorous acid and separates and recovers it as calcium phosphate, (4) describes the generation of hydrogen but not its recovery, and (5) describes the reused catalyst as nickel powder. It does describe activated sludge treatment. Patent Document 2 describes iron and nickel as catalysts, but their shapes are not powders but fine wires and cotton-like bodies, which are completely different in shape. Furthermore, although experiments have been conducted on nickel, no experiments have been conducted on iron. (2) The pH during the reaction is not described, and in the examples, the reaction is carried out without adjusting the pH to alkali. (3) The reaction temperature is 60°C or higher, and in particular, it is as high as 90°C in the examples, and it is described that the reaction does not occur at 40°C. In addition, there is no description of activated sludge treatment and hydrogen generation and recovery. Patent Document 3 describes a plating waste liquid treatment apparatus that forms ozone generated by an ozone generator into microbubbles by a microbubble generator and performs electrolytic oxidation on nickel ion removal plating waste liquid using the ozone, thereby oxidizing hypophosphite ions and phosphite ions and decomposing organic components contained in the waste liquid.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] In the above prior patent documents, there is no description of efficiently reacting under alkali, with an iron catalyst, and at a low temperature. An efficient reaction has not been achieved at a low temperature, and a large amount of heating energy is used. Furthermore, most or all of the useful components (nickel component, phosphite component, organic component, and generated hydrogen) contained in the electroless plating waste liquid have not been sufficiently separated, recovered, and effectively utilized. Moreover, according to the processing apparatus of Patent Document 3, it is considered not practical because it requires expensive equipment and the initial cost and running cost are high.

[0009] In view of the above problems, the inventors of the present invention have conducted intensive research on a rational treatment method for electroless nickel plating waste liquid and the effective utilization of its recovered products, and as a result, have completed the present invention. That is, the present invention solves the above-mentioned drawbacks, reacts efficiently with a significant reduction in heating energy, and further recovers and effectively utilizes all useful components (nickel component, hypophosphorous acid component, and further organic components) contained in the waste liquid and the hydrogen generated. This is the problem to be solved.

Means for Solving the Problems

[0010] In order to solve the above problems, the present invention is shown below. 1. A reaction step of reacting an electroless plating waste liquid containing a nickel component and hypophosphorous acid with iron powder as a catalyst under alkaline conditions at 18 °C or higher and lower than 50 °C to generate phosphorous acid and hydrogen; A hydrogen recovery step of recovering the hydrogen generated in the reaction step; A nickel-coated iron powder recovery step of recovering the nickel-coated iron powder contained in the reaction solution obtained in the reaction step; After the nickel-coated iron powder recovery step, a calcium material for generating calcium phosphite salt is further added to generate calcium phosphite salt, and the generated calcium phosphite salt is separated to recover the calcium phosphite. An electroless plating waste liquid treatment method characterized by comprising a calcium phosphite recovery step. 2. The electroless plating waste liquid treatment method according to 1 above, wherein the alkaline pH is 8 or higher. 3. The electroless plating waste liquid treatment method according to 1 above, wherein the nickel-coated iron powder recovered in the nickel-coated iron powder recovery step is further reused as a catalyst in a new electroless plating waste liquid. 4. The method for treating electroless plating waste liquid according to item 1 above, comprising a step of subjecting the waste liquid after the calcium phosphite recovery step to activated sludge treatment to recover the organic matter contained in the waste liquid after the calcium phosphite recovery step as activated sludge. 5. Utilize the recovered hydrogen and calcium phosphite, The method for treating electroless plating waste liquid according to item 1 above, wherein the nickel-coated iron powder recovered in the nickel-coated iron powder recovery step is further reused as a catalyst in a new electroless plating waste liquid. 6. The method for treating electroless plating waste liquid according to item 5 above, wherein the waste liquid after the calcium phosphite recovery step is subjected to activated sludge treatment to recover the organic matter contained in the waste liquid after the calcium phosphite recovery step as activated sludge and the activated sludge is utilized. 7. A reaction means for reacting an electroless plating waste liquid containing a nickel component and hypophosphorous acid with iron powder as a catalyst under alkaline conditions and at a temperature of 18°C or higher and lower than 50°C to generate phosphorous acid and hydrogen, A hydrogen recovery means for recovering the hydrogen generated in the reaction means, A nickel-coated iron powder recovery means for recovering the nickel-coated iron powder contained in the reaction solution obtained in the reaction means, An electroless plating waste liquid treatment system comprising, after the nickel-coated iron powder recovery means, further adding a water-soluble calcium salt to generate a calcium phosphite salt, separating and dehydrating the generated calcium phosphite salt to recover the calcium phosphite. 8. The electroless plating waste liquid treatment system according to item 7 above, wherein the alkaline pH is 8 or higher. 9. The electroless plating waste liquid treatment system according to item 7 above, wherein the calcium phosphite recovery means separates and dehydrates the generated calcium phosphite salt to recover the calcium phosphite. 10. The electroless plating waste liquid treatment system according to item 7 above, wherein the nickel-coated iron powder recovered in the nickel-coated iron powder recovery means is further reused in a new electroless plating waste liquid. 11. The electroless plating waste liquid treatment system according to item 7 above, further comprising activated sludge recovery means for subjecting the waste liquid after the calcium phosphite recovery means to activated sludge treatment to recover the organic matter contained in the waste liquid after the calcium phosphite recovery means as activated sludge. 12. The electroless plating waste liquid treatment system according to item 7 above, wherein the recovered hydrogen and calcium phosphite are utilized, and the nickel-coated iron powder recovered in the nickel-coated iron powder recovery means is reused as a catalyst in a new electroless plating waste liquid. 13. The electroless plating waste liquid treatment system according to item 12 above, wherein the waste liquid after the calcium phosphite recovery means is subjected to activated sludge treatment to recover the organic matter contained in the waste liquid after the calcium phosphite recovery means as activated sludge, and the activated sludge is utilized.

Advantages of the Invention

[0011] According to the electroless nickel plating waste liquid treatment method and system of the present invention, nickel components, hypophosphorous acid (useful phosphorus component), phosphorous acid components (useful phosphorus component), hydrogen, and, if necessary, organic components can be industrially and efficiently separated and recovered from this plating waste liquid by a simple method or system. Furthermore, these recovered materials can be effectively utilized or reused, which is very useful both energetically and socially, and is a method and system suitable for SDGs. That is, all useful or previously discarded components (nickel components, phosphorous acid components, and further organic components) contained in the waste liquid and the generated hydrogen are recovered and effectively utilized. In addition, since it is under alkaline conditions and uses an iron catalyst, the reaction can be sufficiently carried out even at low temperatures. Also, non-heating can be achieved even in the recovery of calcium phosphite. In these cases, heating energy can be significantly reduced, which is very useful socially. Furthermore, the generated nickel-coated iron powder can be separated and recovered without being discarded and reused as a catalyst for this reaction, which is very useful.

Brief Description of the Drawings

[0012]

Figure 1

Embodiments for Carrying Out the Invention

[0013] Hereinafter, the present invention will be described in detail. The matters shown here are exemplary and for exemplarily explaining the embodiments of the present invention, and are described for the purpose of providing an explanation that can most effectively and without difficulty understand the principle and conceptual features of the present invention. In this regard, it is not intended to show the structural details of the present invention to an extent greater than necessary for a fundamental understanding of the present invention, and it is to clarify for those skilled in the art how some forms of the present invention are actually embodied by the description in combination with the drawings.

[0014] 1. Electroless plating waste liquid treatment method The electroless plating waste liquid treatment method of the present invention comprises a reaction step of reacting an electroless plating waste liquid containing a nickel component and hypophosphorous acid with iron powder as a catalyst under alkaline conditions and at a temperature of 18 °C or higher and lower than 50 °C to produce phosphorous acid and hydrogen, a hydrogen recovery step of recovering the hydrogen generated in the reaction step, a nickel-coated iron powder recovery step of recovering the nickel-coated iron powder contained in the reaction solution obtained in the reaction step, and after the nickel-coated iron powder recovery step, further adding a water-soluble calcium salt to produce calcium phosphite, and separating the produced calcium phosphite to recover the calcium phosphite. The electroless plating waste liquid treatment method of the present invention will be described based on FIG. 1.

[0015] (1) Reaction step; This reaction step is a step of generating phosphorous acid and hydrogen using a predetermined electroless plating waste liquid under alkaline conditions with an iron powder catalyst. The electroless nickel plating waste solution (hereinafter referred to as "plating waste solution") is mainly a nickel plating waste solution using sodium hypophosphite as a reducing agent. This plating waste solution refers to, for example, when electroless nickel plating is performed with a prepared plating solution, sodium hypophosphite used as a reducing agent is oxidized, and as sodium phosphite is gradually generated, the plating function deteriorates, and a new plating solution is replenished with Ni 2+ even though it contains a considerable amount, it refers to a bath solution to be discarded in which the replating function during bath preparation is not sufficiently exhibited.

[0016] The composition of the plating waste solution varies depending on the bath preparation composition, plating conditions, etc. An example of the composition of this plating waste solution is shown. In many cases, Ni( 2+ ) can be about 4 to 7 g / L, and H2PO2( 2- ) can be about 6 to 60 g / L. In addition, a predetermined amount of HPO3( 2- ), SO4( 2- ), a chelating agent, and Na( + ) are included. The hydrogen ion concentration of the plating waste solution is usually about pH 4 to 6. However, the plating waste solution to be treated in the present invention is not limited to those having the above composition.

[0017] The reaction is carried out under alkaline conditions. This pH only needs to be alkaline, that is, exceeding 7, and various values can be taken within this range. Among them, a pH of 8 or more is preferable. The upper limit can be 12, and preferably 11. Also, this pH can preferably be carried out at 8 to 10. This pH adjustment can use an alkaline agent such as sodium hydroxide or potassium hydroxide. If the pH is too high, for example, about 11 to 12, there may be an ammonia odor caused by ammonia contained in the plating waste solution. Also, the reaction is carried out at a relatively low temperature of 18°C or higher and less than 50°C. Even at this temperature, the reaction proceeds sufficiently under alkaline conditions and in the presence of an iron catalyst. In fact, in Examples 1 to 3, the reaction proceeds appropriately even at 20 to 24°C. Iron powder is more reactive than nickel powder. The reaction temperature can be 18 to 45°C, 18 to 40°C, 18 to 30°C, 18 to 25°C, 20 to 45°C, 20 to 40°C, 20 to 35°C, or 20 to 30°C within the range of 18°C or higher and less than 50°C. Also, the temperatures of the lower limit and the upper limit of the temperature range can be used in appropriate combinations. In particular, when an activated sludge treatment step is provided, since the optimum temperature of activated sludge is said to be 25 to 37°C, it is preferably 20 to 40°C, preferably 25 to 40°C. When reacting at a higher temperature than this, it becomes necessary to cool the treatment liquid before the activated sludge treatment, which is not preferable. Furthermore, this reaction vessel is often a tank whose inner surface is coated with resin or a container made of FRP. Even in the former case, since the reaction is carried out at a low temperature, the resin on the inner surface does not peel off and it is safe.

[0018] The catalyst uses the iron powder. And nickel powder can also be added thereto. The shape, size, etc. of this iron powder or nickel powder are not particularly limited. This size can usually be about 0.1 to 1 mm, preferably about 0.2 to 0.5 mm.

[0019] (2) Hydrogen recovery step; The hydrogen recovery step is a step of recovering hydrogen generated in the reaction step. In the process of the electroless plating reaction, hydrogen gas is generated, so the start of this gas generation and the end of its stop are used as a measure of the end point. After generating this gas to form bubbles, it is usually possible to complete the treatment by aging for 0.5 hours or more, preferably 1 to 2 hours. The method for recovering the hydrogen is not particularly limited. For example, hydrogen can be recovered into a hydrogen container or the like through a hydrogen outlet pipe provided on the upper side of the reaction vessel.

[0020] (3) Nickel-coated iron powder recovery process; After the plating reaction, nickel-coated iron powder is produced in which nickel and phosphorus are coated on the surface of the iron powder. The nickel-coated iron powder recovery process is a process of recovering the nickel-coated iron powder contained in the reaction solution obtained in the reaction process. Also, solid-liquid separation can be performed from this reaction solution to recover nickel-coated iron powder from the solid phase. The shape of the recovered nickel-coated iron powder and the method thereof are not particularly limited. For example, it can be recovered as it is in the lower layer portion containing nickel-coated iron powder (a dispersion or paste-like substance in which nickel-coated iron powder is concentrated and dispersed) excluding the supernatant liquid (the supernatant) obtained by allowing the reaction solution to stand and separate. In this case, it is very convenient because filtration means or dehydration means for removing water are not required. Also, it may be used as the recovered nickel-coated iron powder obtained by separating the reaction solution by filtration, pressure dehydration, centrifugation, etc. and dehydrating it if necessary. Also, when used repeatedly, as shown in Example 3, although the catalytic activity decreases, the catalyst concentration increases, so the processing capacity can be prevented from decreasing. Also, when used repeatedly, the reaction temperature can be set to 35°C or higher and lower than 50°C, or 40°C or higher and lower than 50°C. Furthermore, the recovered nickel-coated iron powder can be crushed or pulverized to obtain a crushed product or powder product in which iron is exposed on its surface. In the case of a dispersion in which the nickel-coated iron powder is dispersed or an undried dehydrated product that has not undergone drying, it can be reused without using thermal energy for drying, which is very useful. Also, in the crushed / pulverized product, iron, which has a greater catalytic effect than nickel, is exposed, which is preferable in terms of the catalytic effect. The various recovered nickel-coated iron powders can be reused as a catalyst in a new electroless plating waste liquid. Also, the nickel-coated iron powder can be recovered as a metal nickel component, and this recovered nickel component can also be utilized as a valuable metal.

[0021] (4) Calcium phosphite recovery process; Hypophosphorous acid, which is contained in a large amount in the plating waste liquid, is oxidized under the reaction conditions to generate phosphorous acid. In the calcium phosphite recovery step, after separating and recovering the nickel-coated iron powder, a calcium material for generating the calcium phosphite salt is further added to the separation liquid to generate a calcium phosphite salt, and the generated calcium phosphite salt is separated and dehydrated to recover the calcium phosphite. The content of the hypophosphorous acid is not particularly limited, but for example, it can be about 0.8 to 20 g / L (see Tables 1 to 4). Examples of the calcium material for generating the calcium phosphite salt include slaked lime, lime milk containing slaked lime, and calcium chloride. In short, as these compounds, any calcium material that reacts to form a precipitate of calcium phosphite salt can be applied without particular limitation. Representative examples include slaked lime or lime milk. The reaction time is not particularly limited, but usually, it can be about 0.5 to 10 hours, preferably about 1 to 3 hours. Also, the method (or apparatus) for separating and recovering the generated calcium phosphite salt from the solid-liquid layer is not particularly limited. For example, filtration by a filtration device, centrifugation by a centrifuge, non-heated pressure dehydration by a non-heated pressure dehydrator, vacuum or reduced-pressure dehydration by a vacuum or reduced-pressure dehydrator, etc. can be used to separate and dehydrate the solid matter. These are usually excellent in terms of reducing heating energy and SDGs due to non-heating. In the mother liquor (or filtrate) treated as described above, usually, the actual Ni 2+ can be 300 ppm or less, particularly about 10 to 300 ppm, and the hypophosphorous acid component can be, for example, 100 ppm or less. The nickel recovery rate can be 95% or more, particularly 95 to 100%, and the hypophosphorous acid recovery rate can be 99 to 100% (see Tables 1, 3, and 4). Also, as described above, the recovered hydrogen and calcium phosphite can be utilized, and further, the recovered nickel-coated iron powder can be reused as a catalyst in a new electroless plating waste liquid. Furthermore, calcium phosphite salts or calcium phosphate salts obtained by oxidizing them can also be used as phosphorus-based fertilizers.

[0022] (5) Activated sludge treatment process; The activated sludge treatment process is a process of subjecting the waste liquid (filtrate, mother liquor) after the calcium phosphite recovery process to activated sludge treatment to decompose the organic substances contained in the waste liquid and extracting the grown microorganisms as dewatered sludge. Also, trace amounts of residual phosphorous acid are taken up by the microorganisms in the activated sludge. When the amount of organic substances (BOD) is high, it may be diluted in advance with industrial water or treatment liquid generated from other processes. The total amount of activated sludge (MLSS concentration) in the aeration tank is not particularly limited. The residence time depends on the volume of the activated sludge and the treatment amount of the electroless plating waste liquid, but is not particularly limited as long as it can be decomposed and removed to below the specified drainage standards or environmental standards. In this activated sludge treatment, since there is heat generation by microorganisms, the temperature of the liquid itself is appropriately maintained (about 20 - 40°C), so there is no need to heat from the outside, and since the reaction is not carried out at a high temperature of 60°C or 80°C, there is also no need to cool the separated liquid, which is extremely useful in reducing low-temperature thermal energy. The dewatered sludge can be reused as fuel and fertilizer. Also, thereby, all of the active ingredients (nickel, hypophosphorous acid, hydrogen generation components, and further organic components) contained in the plating waste liquid can be utilized or reused.

[0023] (6) Treatment effect after the calcium phosphite recovery process or the activated sludge treatment process; As described above, in addition to utilizing the recovered hydrogen and calcium phosphite, and further reusing the recovered nickel-coated iron powder as a catalyst in a new electroless plating waste liquid, the waste liquid after the calcium phosphite recovery step can be subjected to activated sludge treatment to recover the organic matter contained in the waste liquid after the calcium phosphite recovery step as activated sludge and utilize the activated sludge. Thereby, all of the active ingredients (nickel, hypophosphorous acid, hydrogen generation components, and further organic components) contained in the waste liquid can be utilized or reused. By sequentially performing the above steps, the nickel ion concentration can usually be 200 ppm or less, particularly 160 ppm or less, and further 1 ppm or less, the phosphorus concentration can usually be 100 ppm or less, and the BOD concentration can usually be 30 ppm or less, preferably 15 ppm or less. The recovery rate of each useful component is also high, and the content of these components in the drainage can also be reduced, so that it is possible to discharge the wastewater with confidence. In addition, the recovered calcium phosphite can be used as a rust preventive pigment, filler, and fertilizer, or can be utilized as a ceramic material or fertilizer of calcium phosphate by oxidative firing. Furthermore, the dehydrated sludge obtained from the activated sludge treatment is used as fuel, fertilizer, etc.

[0024] 2. Electroless Plating Waste Liquid Treatment System This electroless plating waste liquid treatment system includes a reaction means for reacting an electroless plating waste liquid containing a nickel component and hypophosphorous acid with iron powder as a catalyst under alkaline conditions and at a temperature of 18 °C or higher and lower than 50 °C to generate phosphorous acid and hydrogen, a hydrogen recovery means for recovering the hydrogen generated in the reaction system, a nickel-coated iron powder recovery means for recovering the nickel-coated iron powder contained in the reaction liquid obtained in the reaction means, and after the nickel-coated iron powder recovery means, further adding a calcium material for generating calcium phosphite salt such as water-soluble calcium salt to generate calcium phosphite salt, and separating the generated calcium phosphite salt to recover the calcium phosphite. It is characterized by comprising a calcium phosphite recovery means. All the descriptions of "steps" in the waste liquid treatment method can be substantially replaced with all the "means" in the "waste liquid treatment system" and are all applicable. For example, the catalyst described in the waste liquid treatment method can be applied. In addition, a reuse system can be provided in which the nickel-coated iron powder recovered in the metal powder recovery system is further reused in a new plating waste liquid. An activated sludge recovery system can be provided in which the waste liquid after the calcium phosphite recovery system is subjected to activated sludge treatment to recover the organic matter contained in the waste liquid after the calcium phosphite recovery step as activated sludge. The recovered hydrogen and calcium phosphite can be utilized, and the nickel-coated iron powder recovered in the metal powder recovery step can also be reused as a catalyst in a new electroless plating waste liquid. Also, as described above, in addition to utilizing the recovered hydrogen and calcium phosphite and further reusing the recovered nickel-coated iron powder as a catalyst in a new electroless plating waste liquid, the waste liquid after the calcium phosphite recovery means is subjected to activated sludge treatment to recover the organic matter contained in the waste liquid after the calcium phosphite recovery means as dehydrated sludge and utilize it. Thereby, a system can be obtained in which all the active ingredients contained in the waste liquid can be utilized or reused.

Example

[0025] 3. Specific Embodiments Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to these examples.

[0026] Example 1; 〔Nickel and Phosphorus Recovery Method〕 Add 1 to 5% by mass of iron powder to the electroless nickel waste liquid. Then, add sodium hydroxide to adjust the pH to 9 and the temperature to 25°C, and stir for 1 hour. The actual reaction ends in about 30 minutes. From the above, 95% or more of the nickel (initial concentration 4000 - 5000 mg / L) in the electroless nickel waste liquid can be recovered as metallic nickel, and 99% or more of the phosphorus (5000 - 15000 mg / L) in hypophosphorous acid can be oxidized. Thereafter, it is allowed to stand for separation, and then the nickel-coated iron powder can be reused by removing the separated liquid. In addition, the precipitated nickel-coated iron powder can be recycled as nickel sludge. Sulfuric acid (nitric acid / hydrochloric acid) and lime milk are added to the removed supernatant liquid to produce calcium phosphite. Thereafter, calcium phosphite can be recovered by various dehydrators. From the above, more than 90%, for example, about 97% of phosphorus (initial concentration 20,000 - 30,000 mg / L) in the electroless nickel waste liquid can be recovered, and this can be recycled as a fertilizer raw material or as a substitute for phosphate ore. Furthermore, regarding the recycling of calcium phosphite, by using a belt filter with a water washing function, soluble impurities can be removed, and high-purity calcium phosphite can be recovered.

[0027]

Table 1

[0028] Example 2; 〔Advantages of iron powder in the novel treatment method for electroless nickel waste liquid〕 The advantages of using iron powder in the hypophosphorous acid oxidation treatment on the alkaline side were verified. Simulated waste liquid was used for the verification, and 100-mesh iron powder and 100-mesh nickel powder were used as catalysts.

[0029] (1) Composition of simulated waste liquid The above composition is shown in Table 2.

[0030]

Table 2

[0031] (2) Test method The reaction temperature was tested at room temperature (22 - 24°C). 1.0 g of metal powder was added to 100 mL of simulated waste liquid and stirred. 25 mass% caustic soda was added to adjust the pH to 9. As the reaction proceeds, the pH drops, so 25 mass% caustic soda is added as appropriate to maintain the pH at 9. Every 15 minutes, 5 mL of the simulated waste liquid was withdrawn, and the hypophosphorous acid concentration in the filtrate was measured by electrophoresis.

[0032] (3) Test Results The test results are shown in Table 3.

[0033]

Table 3

[0034] Example 3; [Examination of Hypophosphorous Acid Oxidation Reaction Due to Different Catalysts] The oxidation of hypophosphorous acid in electroless nickel waste liquid was examined using three types of catalysts: iron powder, nickel powder, and nickel - coated iron powder (iron powder actually used repeatedly about 100 times on site, and the component is nickel - phosphorus powder). 100 - mesh iron powder and nickel powder were used. The test method was the same as before. After adding the metal powder of the catalyst to the waste liquid, 25 mass% sodium hydroxide was added to adjust the pH to 9.

[0035]

Table 4

[0036]

Table 5

[0037] As described above, according to the method for treating electroless nickel plating waste liquid of the present invention, Ni 2+ and phosphorous acid and organic acid can be industrially and efficiently separated and removed from the plating waste liquid by a simple operation, and the recycled materials in each process can be reused and effectively utilized. Therefore, the present invention is a technology very suitable for SDGs and can greatly contribute to society. Furthermore, it can be made pollution-free to a disposable state, and its industrial utilization value is also very large in this regard.

Industrial Applicability

[0038] The present invention is used to widely and strongly promote the carbon neutrality of society by separating, recovering, and effectively utilizing most or all of the components contained in the electroless nickel plating waste liquid. The present invention relates to a method and a system for treating electroless nickel plating waste liquid, which industrially and efficiently separate and remove nickel ions, hypophosphorous acid components, hydrogen generation components, and further organic components remaining and dissolved in the electroless nickel plating waste liquid to make it harmless to a disposable state.

Claims

1. A reaction step of reacting an electroless plating waste liquid containing a nickel component and hypophosphorous acid with iron powder as a catalyst under alkaline conditions and at a temperature of 18°C or higher and lower than 50°C to produce phosphorous acid and hydrogen; A hydrogen recovery step of recovering the hydrogen generated in the reaction step; A nickel-coated iron powder recovery step of recovering nickel-coated iron powder contained in the reaction solution obtained in the reaction step; After the nickel-coated iron powder recovery step, a calcium material for generating calcium phosphite is further added to generate calcium phosphite, and the generated calcium phosphite is separated and dehydrated to recover the calcium phosphite. An electroless plating waste liquid treatment method characterized by comprising a calcium phosphite recovery step.

2. The electroless plating waste liquid treatment method according to claim 1, wherein the alkaline pH is 8 or higher.

3. The electroless plating waste liquid treatment method according to claim 1, wherein the nickel-coated iron powder recovered in the nickel-coated iron powder recovery step is further reused as a catalyst in a new electroless plating waste liquid.

4. The electroless plating waste liquid treatment method according to claim 1, comprising a step of subjecting the waste liquid after the calcium phosphite recovery step to activated sludge treatment to recover the organic matter contained in the waste liquid after the calcium phosphite recovery step as activated sludge.

5. Utilize the recovered hydrogen and the calcium phosphite, The electroless plating waste liquid treatment method according to claim 1, wherein the nickel-coated iron powder recovered in the nickel-coated iron powder recovery step is further reused as a catalyst in a new electroless plating waste liquid.

6. The electroless plating waste liquid treatment method according to claim 5, wherein the waste liquid after the calcium phosphite recovery step is subjected to activated sludge treatment to recover the organic matter contained in the waste liquid after the calcium phosphite recovery step as activated sludge and utilize the activated sludge.

7. A reaction means for reacting an electroless plating waste liquid containing a nickel component and hypophosphorous acid with iron powder as a catalyst under alkaline conditions at a temperature of 18°C or higher and lower than 50°C to produce phosphorous acid and hydrogen; A hydrogen recovery means for recovering hydrogen generated in the reaction system; A nickel-coated iron powder recovery means for recovering nickel-coated iron powder contained in the reaction solution obtained in the reaction step; A calcium phosphite recovery means for adding a calcium material for generating calcium phosphite salt after the nickel-coated iron powder recovery means to generate calcium phosphite salt, separating and dehydrating the generated calcium phosphite salt to recover the calcium phosphite. An electroless plating waste liquid treatment system characterized by comprising:

8. The electroless plating waste liquid treatment system according to claim 7, wherein the alkaline pH is 8 or more.

9. The electroless plating waste liquid treatment system according to claim 7, wherein the calcium phosphite recovery means separates the generated calcium phosphite salt to recover the calcium phosphite.

10. The electroless plating waste liquid treatment system according to claim 7, wherein the nickel-coated iron powder recovered by the nickel-coated iron powder recovery means is further reused in a new electroless plating waste liquid.

11. The electroless plating waste liquid treatment system according to claim 7, further comprising an activated sludge recovery means for subjecting the waste liquid after the calcium phosphite recovery system to activated sludge treatment to recover the organic matter contained in the waste liquid after the calcium phosphite recovery means as activated sludge.

12. Utilize the recovered hydrogen and the calcium phosphite, The electroless plating waste liquid treatment system according to claim 7, wherein the nickel-coated iron powder recovered by the nickel-coated iron powder recovery means is further reused as a catalyst in a new electroless plating waste liquid.

13. The electroless plating waste liquid treatment system according to claim 12, wherein the waste liquid after the calcium phosphite recovery step is subjected to activated sludge treatment to recover the organic matter contained in the waste liquid after the calcium phosphite recovery means as activated sludge and utilize the activated sludge.

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