Method for treating nickel-containing waste residues generated in nitrogen trifluoride gas preparation process

Abstract

The invention provides a treatment method for nickel-containing waste residues generated in the process of preparing nitrogen trifluoride through an electrolytic method. According to the method, separation and recovery of metal iron and nickel in nickel residues are achieved through fractional precipitation; the technological process is simple, the added materials are non-toxic and harmless, and introduction of ammonia gas is avoided in the nickel recovery process; wastewater generated in the system can be recycled; metal iron and nickel can be efficiently recycled, and a high-value nickel hydroxide product and a high-value ferric hydroxide byproduct are obtained; secondary pollution is avoided, the operation cost is low, and obvious economic benefits and environmental benefits are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of nickel-containing hazardous waste resources, and specifically relates to a method for separating and recovering metallic nickel and iron from nickel-containing waste slag, especially a method for treating nickel-containing waste slag generated during the preparation process of nitrogen trifluoride gas. Background Art

[0002] High-purity nitrogen trifluoride gas plays a crucial role in the microelectronics industry. Nickel-containing waste slag is generated during the preparation of high-purity nitrogen trifluoride gas by the electrolysis method. Whether the nickel-containing waste slag can be properly disposed of is closely related to the development of the nitrogen trifluoride industry.

[0003] The nickel-containing waste slag contains metallic nickel, iron and their fluorides, and is also mixed with some ammonium bifluoride. As a rare precious metal, nickel has extremely high recycling value. If the nickel slag is not treated by a process, it will also cause serious heavy metal pollution and fluoride pollution to the environment.

[0004] At present, there are mainly two treatment methods for the nickel-containing waste slag generated during the preparation of nitrogen trifluoride by the electrolysis method. One is to first neutralize and precipitate fluoride ions with lime, and then treat ammonia nitrogen by a chemical method. The other is to dissolve the nickel-containing waste slag, add a neutralizing agent and a flocculant, and then carry out the subsequent solid-liquid separation process to obtain nickel-containing solids.

[0005] Chinese Patent CN114349079A provides a resource utilization method for nickel slag solid waste in the electrolytic production of nitrogen trifluoride gas, including the following steps: washing of nickel slag, dissolution of nickel slag, complexation of nickel ammonia, washing of Fe(OH)3 precipitate, preparation of Ni(OH)2 product and treatment of colorless filtrate; Chinese Patent CN112645396A relates to a treatment method for fluorine-containing nickel slag generated during the preparation of nitrogen trifluoride, belonging to the technical field of harmless treatment of nickel-containing hazardous waste; the method is as follows: (1) crushing the fluorine-containing nickel slag into solid powder; (2) dissolving the solid powder of the fluorine-containing nickel slag with a hydrofluoric acid solution, stirring at 30°C to 60°C, and adding an oxidizing substance during the stirring and dissolving process until the fluorine-containing nickel slag is completely dissolved to obtain a mixed solution a; (3) adjusting the pH value of the mixed solution a to 3.5 to 4.5 with ammonia water, filtering to obtain iron hydroxide precipitate and mixed solution b; (4) continuing to adjust the pH value of the mixed solution b to 6.5 to 7.5 with ammonia water, filtering to obtain nickel fluoride and mixed solution c; heating and concentrating the mixed solution c, cooling and crystallizing to obtain ammonium fluoride and mixed solution d.

[0006] The above two processes have the following problems. On the one hand, the materials in the process cannot be recycled. The recovery rate of the precious metal nickel is low, no additional by-products are generated, and the resource utilization of solid waste is not realized, resulting in great waste. On the other hand, the process flow is complex, the treatment cost is high, and the obtained products still need subsequent treatment. Summary of the Invention

[0007] The present invention provides a method for treating nickel-containing waste residue generated during the preparation of nitrogen trifluoride by electrolysis. This method realizes the separation and recovery of metallic iron and nickel in the nickel slag through stepwise precipitation; the process flow is simple, and the added materials are all non-toxic and harmless. The introduction of ammonia gas is avoided during the nickel recovery process; the wastewater generated within the system can all be recycled; metallic iron and nickel can be efficiently recovered to obtain high-value nickel hydroxide products and iron hydroxide by-products; there is no generation of secondary pollution, the operating cost is low, and it has obvious economic and environmental benefits.

[0008] To solve the above problems, the present invention adopts the following technical solutions:

[0009] A method for treating nickel-containing waste residue generated during the preparation of nitrogen trifluoride gas, comprising the following steps:

[0010] S1 Stirring and dissolving: Dissolving the nickel-containing waste residue;

[0011] S2 Coprecipitation: Adding a liquid alkali solution to the solution obtained in S1 until pH > 8, and obtaining a mixed precipitate of Fe(OH)3 and Ni(OH)2 and a nickel ammonia solution after suction filtration;

[0012] S3 Precipitate acid dissolution: Dissolving the mixed precipitate of Fe(OH)3 and Ni(OH)2 in dilute nitric acid until completely dissolved;

[0013] S4 First-step precipitation: Adding liquid alkali to the solution completely dissolved in S3 until pH = 5, and obtaining a Fe(OH)3 precipitate and a nickel-containing filtrate after suction filtration;

[0014] S5: Dissolving the Fe(OH)3 precipitate obtained in S4 in dilute nitric acid, stirring and dissolving, and then suction filtering the mixed solution to obtain a Fe(OH)3 product and a Ni(NO3)2 solution. The Ni(NO3)2 solution is mixed with the nickel-containing filtrate obtained in S4 and jointly treated;

[0015] S6 Second-step precipitation: Adding liquid alkali to the liquid obtained by mixing the Ni(NO3)2 solution and the nickel-containing filtrate obtained in S4 until pH > 8, and obtaining a Ni(OH)2 precipitate and a precipitate filtrate after suction filtration;

[0016] S7: Adding a liquid alkali solution to the nickel ammonia solution obtained in S2 until pH > 8, and obtaining a Ni(OH)2 product and a fluoride-containing filtrate after suction filtration. Adding a precipitant to the fluoride-containing filtrate obtained in S7 to obtain a CaF2 precipitate and a precipitate filtrate.

[0017] Preferably, the specific steps of S1 are: adding the dried nickel slag to dilute nitric acid for dissolution, and the dissolution time

[0018] ≤60 min;

[0019] In S1, the solid-liquid mass ratio is 1:6 to 1:8, the concentration of dilute nitric acid is 3M to 4M, and the reaction temperature is 80 to 90 °C.

[0020] Preferably, the liquid caustic solution in S2 is a 40% by mass NaOH solution, O2 is continuously introduced into the reaction system for 30 to 60 minutes, and the reaction temperature is 80 to 90 °C.

[0021] Preferably, an Fe 2+ detection device is provided in S2 until Fe 2+ is completely converted to Fe 3+ The reaction ends. After the reaction ends, the Fe 2+ concentration ≤ 5 ppm.

[0022] Preferably, the concentration of dilute nitric acid in S3 is 3M to 4M.

[0023] Preferably, the liquid caustic in S4, S6 and S7 is a 40% by mass NaOH solution.

[0024] Preferably, the pH of the dilute nitric acid in S5 ≤ 2.

[0025] Preferably, the precipitating agent added to the fluorine-containing filtrate obtained in S7 is solid Ca(OH)2, and the precipitating agent is added until no new precipitate is formed.

[0026] Preferably, the precipitate filtrate obtained in S6 and the precipitate filtrate obtained in S7 are recycled to S2 for coprecipitation.

[0027] The innovation of the present invention lies in:

[0028] After the acid dissolution of the nickel-containing waste residue, the metal cations in the system include most of the Fe 2+ , a small part of the Fe 3+ and Ni 2+ . Since the pH values required for the precipitation of Fe 2+ and Ni 2+ are similar, therefore, before the fractional precipitation, it is necessary to achieve the complete conversion of Fe 2+ to Fe 3+ . However, the dissolved solution is strongly acidic, and under this condition, the conversion rate of Fe 2+ to Fe 3+ is extremely slow. The technology proposed by the present invention first adds liquid caustic to the solution until all metal ions are completely converted into hydroxide precipitates. Under strong alkaline conditions, the rapid and complete conversion of Fe 2+ to Fe 3+ can be achieved, and the oxidation process can be further accelerated by heating and introducing O2 into the system. After complete oxidation, the system only contains Fe(OH)3 and Ni(OH)2. After acid dissolving the precipitate, the metal cations in the system are Fe 3+ and Ni2+ Since the pH values required for the precipitation of Fe 3+ and Ni 2+ differ significantly, a fractional precipitation method is used for their separation. The Fe 2+ alkaline oxidation technology proposed in this invention has a simple implementation method, which solves the problem of incomplete conversion of Fe 2+ to Fe 3+ , greatly improving the conversion rate of Fe 2+ to Fe 3+ and ensuring the smooth progress of the subsequent fractional precipitation process.

[0029] The beneficial effects of this invention are as follows:

[0030] (1) When using this process for the resource treatment of nickel-containing waste residue, the conditions are mild and do not require high temperature and high pressure. The process flow is short, the equipment is simple, and it is easy to operate.

[0031] (2) Dilute nitric acid is used for dissolving the waste residue, and no toxic gas is generated. The nickel slag is completely dissolved, ensuring that valuable metals in the nickel slag are completely recovered. The time consumption is less, and the dissolution process can be completed in less than 1 hour. The required temperature is 80 - 90 °C, and the requirement can be achieved by using steam reflux heating.

[0032] (3) During the precipitation process, liquid alkali is slowly added, and the precipitation temperature is controlled to minimize the particle size of Fe(OH)3 and inhibit the adsorption of Fe(OH)3 on Ni 2+ . In addition, the obtained Fe(OH)3 is washed with dilute nitric acid, which not only ensures the purity of the Fe(OH)3 product but also improves the recovery rate of Ni 2+ .

[0033] (4) This process has a high metal recovery rate. The obtained Ni(OH)2 product quality meets the national standard, and the by-product Fe(OH)3 can also be sold as a product. The waste liquid generated in this process can be used to absorb the waste gas generated during the production process, avoiding secondary pollution. It has obvious economic and environmental benefits. Description of the Drawings

[0034] Figure 1 It is a schematic diagram of the process flow of this invention. Detailed Embodiments

[0035] The technical solutions of this invention will be further described below in combination with specific embodiments. It should be noted that the following examples are only used for detailed description and explanation of this invention, and the application scope of this invention is not limited by the conditions in the examples.

[0036] The nickel-containing waste residue used in the following implementation cases is the nickel-containing waste residue generated during the preparation of high-purity nitrogen trifluoride gas by the electrolysis method. The liquid caustic soda solution in the examples is a NaOH solution with a mass concentration of 40%. The process flow of the examples is as Figure 1 shown.

[0037] Table 1 shows the contents of iron ions and nickel ions in the nickel-containing waste residue.

[0038] Table 1

[0039] Element Fe Ni Content (wt.%) 10.7 23.7

[0040] Example 1

[0041] Take the dried nickel-containing waste residue generated during the preparation of high-purity nitrogen trifluoride gas by the electrolysis method and dissolve it in 4M dilute nitric acid at a solid-liquid mass ratio of 1:6. The reaction temperature is 80°C, and the stirring and dissolution time is 30 minutes. Add liquid caustic soda to adjust the pH value of the above solution to 8.5. To accelerate the complete conversion of Fe 2+ to Fe 3+ , the reaction temperature is 80°C during this process, and the time for introducing O2 is 30 minutes. After sufficient reaction, a mixed precipitate and a filtrate are obtained. Add liquid caustic soda to the above filtrate until the pH value of the solution is 8.5 to obtain Ni(OH)2 product and a fluoride-containing filtrate. Add the above mixed precipitate to dilute nitric acid for dissolution, and adjust the pH value of the solution to 5 after dissolution to obtain Fe(OH)3 precipitate and a nickel-containing filtrate. The Fe(OH)3 precipitate obtained above is washed with dilute nitric acid with a pH value of 2 and then filtered. Obtain Fe(OH)3 by-product and a filtrate, mix the filtrate with the above nickel-containing filtrate for joint treatment, and adjust the pH value of the mixed solution of the filtrate mixed with the nickel-containing filtrate to 8.5 to obtain Ni(OH)2 product and a precipitate filtrate. Add Ca(OH)2 precipitant to the fluoride-containing filtrate, and add the precipitant until no new precipitate is produced to obtain CaF2 precipitate and a precipitate filtrate.

[0042] In this example, the recovery rate of iron is 98.8%, and the recovery rate of nickel is 98.2%.

[0043] Example 2

[0044] Take the dried nickel-containing waste residue generated during the preparation of high-purity nitrogen trifluoride gas by the electrolysis method and dissolve it in 4M dilute nitric acid at a solid-liquid mass ratio of 1:8. The reaction temperature is 80°C, and the stirring and dissolution time is 40 minutes. Add liquid caustic soda to adjust the pH value of the above solution to 8.5. To accelerate the complete conversion of Fe 2+ to Fe 3+, the reaction temperature in this process is 80 °C, and the time for introducing O2 is 30 minutes. After sufficient reaction, a mixed precipitate and a filtrate are obtained. Liquid alkali is added to the above filtrate until the pH value of the solution reaches 8.5, obtaining Ni(OH)2 product and a fluoride-containing filtrate. The above mixed precipitate is added to dilute nitric acid for dissolution, and after dissolution, the pH value of the solution is adjusted to 5, obtaining Fe(OH)3 precipitate and a nickel-containing filtrate. The Fe(OH)3 precipitate obtained in the above process is washed with dilute nitric acid with a pH value of 2 and then filtered. An Fe(OH)3 by-product and a filtrate are obtained, and the filtrate is mixed with the above nickel-containing filtrate for joint treatment. The pH value of the mixed solution of the above filtrate and the nickel-containing filtrate is adjusted to 8.5, obtaining Ni(OH)2 product and a precipitate filtrate. A Ca(OH)2 precipitant is added to the fluoride-containing filtrate, and the precipitant is added until no new precipitate is produced, obtaining CaF2 precipitate and a precipitate filtrate.

[0045] In this example, the recovery rate of iron is 98.6%, and the recovery rate of nickel is 98.5%.

[0046] Example 3

[0047] The nickel-containing waste residue generated during the preparation of high-purity nitrogen trifluoride gas by the electrolysis method after drying is dissolved in 3M dilute nitric acid at a solid-liquid mass ratio of 1:6. The reaction temperature is 80 °C, and the stirring and dissolution time is 30 minutes. Liquid alkali is added to adjust the pH value of the above solution to 8.5. To accelerate the conversion of Fe 2+ completely into Fe 3+ , the reaction temperature in this process is 80 °C, and the time for introducing O2 is 30 minutes. After sufficient reaction, a mixed precipitate and a filtrate are obtained. Liquid alkali is added to the above filtrate until the pH value of the solution reaches 8.5, obtaining Ni(OH)2 product and a fluoride-containing filtrate. The above mixed precipitate is added to dilute nitric acid for dissolution, and after dissolution, the pH value of the solution is adjusted to 5, obtaining Fe(OH)3 precipitate and a nickel-containing filtrate. The Fe(OH)3 precipitate obtained in the above process is washed with dilute nitric acid with a pH value of 2 and then filtered. An Fe(OH)3 by-product and a filtrate are obtained, and the filtrate is mixed with the above nickel-containing filtrate for joint treatment. The pH value of the mixed solution of the above filtrate and the nickel-containing filtrate is adjusted to 8.5, obtaining Ni(OH)2 product and a precipitate filtrate. A Ca(OH)2 precipitant is added to the fluoride-containing filtrate, and the precipitant is added until no new precipitate is produced, obtaining CaF2 precipitate and a precipitate filtrate.

[0048] In this example, the recovery rate of iron is 97.5%, and the recovery rate of nickel is 97.8%.

[0049] Example 4

[0050] The nickel-containing waste residue generated during the preparation of high-purity nitrogen trifluoride gas by the electrolysis method after drying is dissolved in 4M dilute nitric acid at a solid-liquid mass ratio of 1:6. The reaction temperature is 90 °C, and the stirring and dissolution time is 30 minutes. Liquid alkali is added to adjust the pH value of the above solution to 8.5 to accelerate the conversion of Fe 2+ completely into Fe 3+ . The reaction temperature during this process is 90 °C, and the time for introducing O2 is 30 minutes. After sufficient reaction, a mixed precipitate and a filtrate are obtained. Liquid alkali is added to the above filtrate until the pH value of the solution is 8.5 to obtain Ni(OH)2 products and a fluorine-containing filtrate. The above mixed precipitate is added to dilute nitric acid for dissolution, and after dissolution, the pH value of the solution is adjusted to 5 to obtain Fe(OH)3 precipitate and a nickel-containing filtrate. The Fe(OH)3 precipitate obtained above is washed with dilute nitric acid with a pH value of 2 and then filtered. Fe(OH)3 by-products and a filtrate are obtained, and the filtrate is mixed with the above nickel-containing filtrate for joint treatment. The pH value of the mixed solution of the above filtrate and the nickel-containing filtrate is adjusted to 8.5 to obtain Ni(OH)2 products and a precipitate filtrate. A Ca(OH)2 precipitant is added to the fluorine-containing filtrate, and the precipitant is added until no new precipitate is generated to obtain CaF2 precipitate and a precipitate filtrate.

[0051] In this example, the recovery rate of iron is 98.8%, and the recovery rate of nickel is 98.4%.

[0052] Example 5

[0053] The nickel-containing waste residue generated during the preparation of high-purity nitrogen trifluoride gas by the electrolysis method after drying is dissolved in 4M dilute nitric acid at a solid-liquid mass ratio of 1:6. The reaction temperature is 80 °C, and the stirring and dissolution time is 30 minutes. Liquid alkali is added to adjust the pH value of the above solution to 8.5 to accelerate the conversion of Fe 2+ completely into Fe 3+ . The reaction temperature during this process is 80 °C, and the time for introducing O2 is 60 minutes. After sufficient reaction, a mixed precipitate and a filtrate are obtained. Liquid alkali is added to the above filtrate until the pH value of the solution is 8.5 to obtain Ni(OH)2 products and a fluorine-containing filtrate. The above mixed precipitate is added to dilute nitric acid for dissolution, and after dissolution, the pH value of the solution is adjusted to 5 to obtain Fe(OH)3 precipitate and a nickel-containing filtrate. The Fe(OH)3 precipitate obtained above is washed with dilute nitric acid with a pH value of 2 and then filtered. Fe(OH)3 by-products and a filtrate are obtained, and the filtrate is mixed with the above nickel-containing filtrate for joint treatment. The pH value of the mixed solution of the above filtrate and the nickel-containing filtrate is adjusted to 8.5 to obtain Ni(OH)2 products and a precipitate filtrate. A Ca(OH)2 precipitant is added to the fluorine-containing filtrate, and the precipitant is added until no new precipitate is generated to obtain CaF2 precipitate and a precipitate filtrate. The precipitate filtrate is recycled to the liquid obtained after dissolving the nickel-containing waste residue in dilute nitric acid in the next example.

[0054] In this example, the recovery rate of iron is 99.3% and the recovery rate of nickel is 98.9%.

[0055] Comparative Example 1

[0056] The nickel-containing waste residue generated during the preparation of high-purity nitrogen trifluoride gas by electrolysis method after drying is dissolved in 4M dilute nitric acid at a solid-liquid mass ratio of 1:6. The reaction temperature is 80 °C, and the stirring and dissolving time is 30 minutes. Liquid alkali is added to adjust the pH value of the above solution to 8.5. To accelerate the conversion of Fe 2+ completely to Fe 3+ , the reaction temperature is 80 °C during this process. After sufficient reaction, a mixed precipitate and a filtrate are obtained. Liquid alkali is added to the above filtrate until the pH value of the solution is 8.5 to obtain Ni(OH)2 product and a fluoride-containing filtrate. The above mixed precipitate is added to dilute nitric acid for dissolution, and after dissolution, the pH value of the solution is adjusted to 5 to obtain Fe(OH)3 precipitate and a nickel-containing filtrate. The pH value of the above nickel-containing filtrate is adjusted to 8.5 to obtain Ni(OH)2 product and a precipitate filtrate. The Fe(OH)3 precipitate obtained above is washed with dilute nitric acid with a pH value of 2 and then filtered. An Fe(OH)3 by-product and a filtrate are obtained, and the filtrate is mixed with the above nickel-containing filtrate for joint treatment. Ca(OH)2 precipitant is added to the fluoride-containing filtrate, and the precipitant is added until no new precipitate is produced to obtain CaF2 precipitate and a precipitate filtrate.

[0057] In this comparative example, the recovery rate of iron is 92.1% and the recovery rate of nickel is 98.1%.

[0058] The difference between this comparative example and Example 1 is that: O2 is not introduced, and the lack of oxygen introduction affects the conversion of Fe 2+ to Fe 3+ , ultimately affecting the recovery rate of iron and having little effect on the recovery rate of nickel.

[0059] Comparative Example 2

[0060] The nickel-containing waste residue generated during the preparation of high-purity nitrogen trifluoride gas by electrolysis method after drying is dissolved in 4M dilute nitric acid at a solid-liquid mass ratio of 1:6. The reaction temperature is 80 °C, and the stirring and dissolving time is 30 minutes. Liquid alkali is added to adjust the pH value of the above solution to 8.5. To accelerate the conversion of Fe 2+ completely to Fe 3+During this process, the reaction temperature is 80 °C and the time for introducing O2 is 30 minutes. After sufficient reaction, a mixed precipitate and a filtrate are obtained. Liquid alkali is added to the above filtrate until the pH value of the solution reaches 8.5, obtaining Ni(OH)2 product and a fluoride-containing filtrate. The above mixed precipitate is added to dilute nitric acid for dissolution, and after dissolution, the pH value of the solution is adjusted to 5, obtaining Fe(OH)3 precipitate and a nickel-containing filtrate. The pH value of the above nickel-containing filtrate is adjusted to 8.5, obtaining Ni(OH)2 product and a precipitate filtrate. The Fe(OH)3 precipitate obtained in the above process is washed with dilute nitric acid with a pH value of 3 and then filtered. The Fe(OH)3 by-product and a filtrate are obtained, and the filtrate is mixed with the above nickel-containing filtrate for joint treatment. Ca(OH)2 precipitant is added to the fluoride-containing filtrate, and the precipitant is added until no new precipitate is produced, obtaining CaF2 precipitate and a precipitate filtrate.

[0061] In this comparative example, the recovery rate of iron is 98.6% and the recovery rate of nickel is 95.2%.

[0062] The difference between this comparative example and Example 1 lies in that: the Fe(OH)3 precipitate is washed with dilute nitric acid with a pH value of 3 and then filtered. Washing with dilute nitric acid with a pH value of 3 has little effect on the recovery rate of iron, but affects the recovery rate of nickel.

[0063] In summary, as can be seen from the above examples, the technical solution proposed by the present invention can well realize the separation and recovery of metallic iron and nickel in nickel-containing waste residue.

[0064] The upper and lower limits and interval values of the process parameters (solid-liquid ratio, nitric acid concentration, reaction temperature and time) proposed by the present invention can ensure the implementation of this technology, and will not be listed one by one here.

[0065] The above is only used to introduce the specific implementation manners of the present invention in detail, but the technical solution proposed by the present invention is not limited to the above methods. Without departing from the basic principle of this technology, equivalent modifications and changes made by those skilled in the art to the technology proposed by the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for treating nickel-containing waste residue generated in the preparation process of nitrogen trifluoride gas, characterized in that, It includes the following steps: S1 Stirring and dissolving: Dissolving the nickel-containing waste residue; S2 Coprecipitation: Adding a liquid alkali solution to the solution obtained in S1 until pH > 8, and obtaining a mixed precipitate of Fe(OH)3 and Ni(OH)2 and a nickel ammonia solution after suction filtration; S3 Precipitate acid dissolution: Dissolving the mixed precipitate of Fe(OH)3 and Ni(OH)2 in dilute nitric acid until completely dissolved; S4 First-step precipitation: Adding a liquid alkali to the solution completely dissolved in S3 until pH = 5, and obtaining a Fe(OH)3 precipitate and a nickel-containing filtrate after suction filtration; S5: Dissolving the Fe(OH)3 precipitate obtained in S4 in dilute nitric acid, stirring and dissolving, and then suction filtering the mixture to obtain a Fe(OH)3 product and a Ni(NO3)2 solution. The Ni(NO3)2 solution is mixed with the nickel-containing filtrate obtained in S4 and then co-treated; S6 Second-step precipitation: Adding a liquid alkali to the liquid mixture after mixing the Ni(NO3)2 solution and the nickel-containing filtrate obtained in S4 until pH > 8, and obtaining a Ni(OH)2 precipitate and a precipitate filtrate after suction filtration; S7: Adding a liquid alkali solution to the nickel ammonia solution obtained in S2 until pH > 8, and obtaining a Ni(OH)2 product and a fluorine-containing filtrate after suction filtration. Adding a precipitating agent to the fluorine-containing filtrate obtained in S7 to obtain a CaF2 precipitate and a precipitate filtrate.

2. The treatment method of nickel-containing waste residue generated during the preparation process of nitrogen trifluoride gas according to claim 1, characterized in that, The specific steps of S1 are: Adding the dried nickel slag to dilute nitric acid for dissolution, and the dissolution time ≤ 60 min; In S1, the solid-liquid mass ratio is 1:6 to 1:8, the concentration of dilute nitric acid is 3M to 4M, and the reaction temperature is 80 to 90 °C.

3. The treatment method of nickel-containing waste residue generated in the preparation process of nitrogen trifluoride gas according to claim 1, characterized in that, The liquid alkali solution in S2 is a NaOH solution with a mass concentration of 40%, and O2 is continuously introduced during the reaction for 30 to 60 minutes, and the reaction temperature is 80 to 90 °C.

4. The treatment method of nickel-containing waste residue generated in the preparation process of nitrogen trifluoride gas according to claim 1, characterized in that, Fe is equipped in S2 2+ Detection device, until Fe 2+ is converted to Fe 3+ The reaction ends. After the reaction ends, Fe 2+ concentration ≤ 5 ppm 5. The treatment method of nickel-containing waste residue generated during the preparation process of nitrogen trifluoride gas according to claim 1, characterized in that, The concentration of dilute nitric acid in S3 is 3M to 4M.

6. The treatment method of nickel-containing waste residue generated in the preparation process of nitrogen trifluoride gas according to claim 1, characterized in that, The liquid alkali in S4, S6 and S7 is a NaOH solution with a mass concentration of 40%.

7. The treatment method of nickel-containing waste residue generated during the preparation process of nitrogen trifluoride gas according to claim 1, characterized in that, The pH of the dilute nitric acid in S5 ≤ 2.

8. The treatment method of nickel-containing waste residue generated during the preparation process of nitrogen trifluoride gas according to claim 1, characterized in that, The precipitating agent added to the fluorine-containing filtrate obtained in S7 is solid Ca(OH)2, and the precipitating agent is added until no new precipitate is produced.

9. The treatment method of nickel-containing waste residue generated during the preparation process of nitrogen trifluoride gas according to claim 1, characterized in that, The precipitate filtrate obtained in S6 and the precipitate filtrate obtained in S7 are recycled to S2 for coprecipitation.

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