Method for deep purification of waste sulfuric acid in semiconductor industry

Abstract

This invention discloses a method for the deep purification of waste sulfuric acid generated in the semiconductor industry, belonging to the technical field of comprehensive utilization and recycling of waste sulfuric acid in the semiconductor industry. First, the waste sulfuric acid is passed into a hydrogen peroxide removal system. Under heating conditions, a catalyst is added to promote the decomposition of hydrogen peroxide in the waste sulfuric acid. Simultaneously, under the synergistic effect of the catalyst and hydrogen peroxide, metallic impurities in the waste sulfuric acid are induced to form intermediate oxidation products, which is beneficial for the subsequent resin adsorption and impurity removal process. After resin purification, the purified sulfuric acid is finally passed into an evaporation and concentration system, concentrated at 100-200℃ for 3-6 hours to obtain high-purity sulfuric acid. This method not only deeply purifies waste sulfuric acid but also avoids introducing new impurities and secondary pollution to the environment, achieving green and efficient deep purification of waste sulfuric acid.

Description

Technical Field

[0001] This invention belongs to the technical field of waste sulfuric acid recycling and comprehensive utilization in the semiconductor industry, and specifically relates to a method for deep purification of waste sulfuric acid in the semiconductor industry. Background Technology

[0002] Electronic-grade sulfuric acid, also known as high-purity sulfuric acid or ultra-pure sulfuric acid, is a crucial basic chemical reagent indispensable in the development of microelectronics technology and is the electronic chemical used in the largest quantity in chip manufacturing processes. With the rapid development of the domestic semiconductor industry in recent years, the consumption of electronic-grade sulfuric acid has been increasing significantly, and the amount of waste sulfuric acid generated has also been increasing year by year. Currently, semiconductor plants typically neutralize the sulfuric acid with acid and then entrust relevant institutions to dispose of it. This method is not only costly and difficult to implement, but also easily leads to a large waste of non-metallic sulfur resources.

[0003] To address the issue of waste sulfuric acid disposal in the semiconductor industry, CN111321423A employs an electrolytic cell with titanium-based lead dioxide as the anode and carbon electrodes as the cathode. This removes hydrogen peroxide from the waste sulfuric acid without electricity, and then regenerates the lead dioxide and sulfuric acid under energized conditions, achieving sulfuric acid recovery. CN113336198B heats the waste sulfuric acid to 25–90°C, causing hydrogen peroxide to decompose and yield dilute sulfuric acid. This dilute sulfuric acid is then concentrated, followed by distillation to produce reagent-grade sulfuric acid. While existing waste sulfuric acid recovery technologies alleviate the semiconductor industry's waste sulfuric acid disposal difficulties to some extent, and the recovered waste sulfuric acid can be reused as industrial or reagent-grade sulfuric acid after treatment, current methods suffer from complex processes and high energy consumption, failing to meet increasingly stringent environmental requirements. Therefore, there is a need to invent a green and efficient method for treating waste sulfuric acid in the semiconductor industry, establishing a resource recycling model based on sulfur, solving common industry problems, reducing operational difficulties for semiconductor companies, and safeguarding the localization, greening, and healthy development of the semiconductor industry. Summary of the Invention

[0004] The purpose of this invention is to provide a method for deep purification of waste sulfuric acid in the semiconductor industry. This method can not only achieve green and efficient recycling of waste sulfuric acid, but also deeply remove hydrogen peroxide and metal impurities from the waste sulfuric acid to obtain high-purity sulfuric acid products, and ultimately realize the recycling of sulfur resources.

[0005] To achieve the above objectives, a method for deep purification of waste sulfuric acid in the semiconductor industry is provided, comprising the following steps:

[0006] (1) The recovered waste sulfuric acid is heated to 50-100℃, and a catalyst is added to promote the decomposition of hydrogen peroxide in the waste sulfuric acid. Under the synergistic effect of the catalyst and hydrogen peroxide, the metal impurities in the waste sulfuric acid form intermediate oxidation products that are conducive to resin adsorption. At the same time, the tail gases such as oxygen and acid mist generated during the reaction process are collected and treated harmlessly.

[0007] (2) When the concentration of hydrogen peroxide in the waste sulfuric acid from step (1) is ≤0.002%, the reaction is stopped and the waste sulfuric acid is cooled to 25-45°C.

[0008] (3) At room temperature, the waste sulfuric acid from step (2) was treated with mixed resin to remove metal impurities and samples were taken for analysis.

[0009] (4) After removing impurities in step (3), the sulfuric acid is evaporated and concentrated at 100-200℃ for 3-6 hours to obtain high-purity sulfuric acid product. At the same time, the tail gas in the reaction process is collected and treated harmlessly.

[0010] Furthermore, the concentration of the waste sulfuric acid mentioned in step (1) is 60-85%.

[0011] Preferably, the heating temperature of the waste sulfuric acid in step (1) is 55-85°C.

[0012] Preferably, the catalyst in step (1) is one or a combination of two or more of the following: copper wire, zeolite, calcium oxide, iron oxide, aluminum oxide, manganese dioxide, copper oxide, silicon oxide, calcium hydroxide, and calcium chloride.

[0013] Preferably, the exhaust gas in step (1) is absorbed countercurrently using NaOH solution.

[0014] Further, repeat step (2) until the hydrogen peroxide concentration in the waste sulfuric acid is ≤0.002%.

[0015] Furthermore, the resin used in step (3) is a mixture of two or more of the following resin types: UPW650, C160, S910, ZGA307FM, S960, S985, and RCS81.

[0016] Preferably, in step (3), the resin needs to be washed repeatedly with ultrapure water 15-30 times.

[0017] Preferably, the flow rate of the resin column in step (3) is 1.5 to 3.5 BV / min, and the purification time is 90 to 120 min.

[0018] Furthermore, all experimental procedures involved in this invention require strict control of environmental pollution.

[0019] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0020] 1. Compared with existing processes, the present invention uses a combination of heating and catalyst to remove hydrogen peroxide from waste sulfuric acid, which not only reduces energy consumption but also effectively promotes the decomposition of hydrogen peroxide in waste sulfuric acid.

[0021] 2. The waste gas generated by this invention is treated to render it harmless and will not cause secondary pollution to the environment.

[0022] 3. This invention uses resin to remove metal impurities from waste sulfuric acid, achieving efficient removal of metal impurities from waste sulfuric acid without introducing new impurities.

[0023] 4. Compared with existing technologies, the process technology adopted in this invention is simple to operate and can deeply purify the recovered waste sulfuric acid, solving the problem of waste sulfuric acid treatment for the semiconductor industry, and also realizing the green and efficient recycling of sulfur. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are merely for the purpose of more clearly illustrating the technical solutions in the embodiments of the present invention or the prior art. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0025] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0027] This invention provides a technical solution: a method for deep purification of waste sulfuric acid in the semiconductor industry, comprising the following steps:

[0028] (1) The recovered waste sulfuric acid is heated to 50-100℃, and a catalyst is added to promote the decomposition of hydrogen peroxide in the waste sulfuric acid. Under the synergistic effect of the catalyst and hydrogen peroxide, the metal impurities in the waste sulfuric acid form intermediate oxidation products that are conducive to resin adsorption. At the same time, the tail gases such as oxygen and acid mist generated during the reaction process are collected and treated harmlessly.

[0029] (2) When the concentration of hydrogen peroxide in the waste sulfuric acid from step (1) is ≤0.002%, the reaction is stopped and the waste sulfuric acid is cooled to 25-45°C.

[0030] (3) At room temperature, the waste sulfuric acid from step (2) was treated with mixed resin to remove metal impurities and samples were taken for analysis.

[0031] (4) After removing impurities in step (3), the sulfuric acid is evaporated and concentrated at 100-200℃ for 3-6 hours to obtain high-purity sulfuric acid product. At the same time, the tail gas in the reaction process is collected and treated harmlessly.

[0032] Table 1. Detection results of waste sulfuric acid samples 1-3

[0033]

[0034]

[0035] The waste sulfuric acid samples were all taken from different semiconductor manufacturers.

[0036] Detection methods

[0037] The high-purity sulfuric acid obtained in the following examples was tested in accordance with the national standard for electronic grade sulfuric acid (GB / T 41881-2022).

[0038] Example 1

[0039] A method for deep purification of waste sulfuric acid in the semiconductor industry includes the following steps:

[0040] (1) The recovered waste sulfuric acid sample No. 1 was heated to 60°C, and copper wire and zeolite were added as catalysts (the mass ratio of copper wire and zeolite was 10:1) to promote the decomposition of hydrogen peroxide in the waste sulfuric acid. Under the synergistic effect of the catalyst and hydrogen peroxide, the metal impurities in the waste sulfuric acid formed intermediate oxidation products that were conducive to resin adsorption. At the same time, the oxygen, acid mist and other tail gases generated during the reaction were collected and treated harmlessly.

[0041] (2) When the concentration of hydrogen peroxide in the waste sulfuric acid from step (1) is ≤0.002%, the reaction is stopped and the waste sulfuric acid is cooled to 30°C.

[0042] (3) At room temperature, the waste sulfuric acid from step (2) was treated with a mixed resin (S960, S985 and RCS81 in a volume ratio of 2:1:3) to remove metal impurities, and samples were taken for analysis.

[0043] (4) After removing impurities in step (3), the sulfuric acid is evaporated and concentrated at 200°C for 5 hours to obtain high-purity sulfuric acid product. At the same time, the tail gas in the reaction process is collected and treated harmlessly.

[0044] Table 2 Detection results of sample from Example 1

[0045]

[0046] As can be seen from Example 1 and Table 2, the sulfuric acid obtained by using the method provided by this invention from waste sulfuric acid sample No. 1 meets the standard for electronic grade sulfuric acid.

[0047] Example 2

[0048] A method for deep purification of waste sulfuric acid in the semiconductor industry includes the following steps:

[0049] (1) The recovered waste sulfuric acid sample No. 2 was heated to 70°C, and copper wire was added as a catalyst to promote the decomposition of hydrogen peroxide in the waste sulfuric acid. Under the synergistic effect of the catalyst and hydrogen peroxide, the metal impurities in the waste sulfuric acid formed intermediate oxidation products that were conducive to resin adsorption. At the same time, the tail gases such as oxygen and acid mist in the reaction process were collected and treated harmlessly.

[0050] (2) When the concentration of hydrogen peroxide in the waste sulfuric acid from step (1) is ≤0.002%, the reaction is stopped and the waste sulfuric acid is cooled to 30°C.

[0051] (3) At room temperature, the waste sulfuric acid from step (2) was treated with a mixed resin (UPW650 and S960 in a volume ratio of 1:3) to remove metal impurities, and samples were taken for analysis.

[0052] (4) After removing impurities in step (3), the sulfuric acid is evaporated and concentrated at 190°C for 4 hours to obtain high-purity sulfuric acid product. At the same time, the tail gas in the reaction process is collected and treated harmlessly.

[0053] Table 3. Detection results of sample from Example 2

[0054]

[0055] As can be seen from Example 2 and Table 3, the sulfuric acid obtained by using the method provided by this invention from waste sulfuric acid sample No. 2 meets the standard for electronic grade sulfuric acid.

[0056] Example 3

[0057] A method for deep purification of waste sulfuric acid in the semiconductor industry includes the following steps:

[0058] (1) The recovered waste sulfuric acid sample No. 3 was heated to 65°C, and copper wire and copper oxide (mass ratio of copper wire to copper oxide was 15:1) were added as catalysts to promote the decomposition of hydrogen peroxide in the waste sulfuric acid. Under the synergistic effect of the catalyst and hydrogen peroxide, the metal impurities in the waste sulfuric acid formed intermediate oxidation products that were conducive to resin adsorption. At the same time, the oxygen, acid mist and other tail gases produced during the reaction were collected and treated to render them harmless.

[0059] (2) When the concentration of hydrogen peroxide in the waste sulfuric acid from step (1) is ≤0.002%, the reaction is stopped and the waste sulfuric acid is cooled to 30°C.

[0060] (3) At room temperature, the waste sulfuric acid from step (2) was treated with a mixed resin (C160 and S910 in a volume ratio of 2:3) to remove metal impurities, and samples were taken for analysis.

[0061] (4) After removing impurities in step (3), the sulfuric acid is evaporated and concentrated at 190°C for 4 hours to obtain high-purity sulfuric acid product. At the same time, the tail gas in the reaction process is collected and treated harmlessly.

[0062] Table 4. Detection results of sample 3 in Example 3

[0063]

[0064]

[0065] As can be seen from Example 3 and Table 4, the sulfuric acid obtained by using the method provided by this invention from waste sulfuric acid sample No. 3 meets the standard for electronic grade sulfuric acid.

[0066] Example 4

[0067] The method and steps are the same as in Example 3, except that the catalyst is copper oxide, which can only achieve an H2O2 content of 0.08%. After processing in steps (3) and (4), the results are as follows:

[0068] Table 5. Detection results of sample 4 in Example 4

[0069]

[0070] As can be seen from Example 4 and Table 5, the sulfuric acid obtained from waste sulfuric acid sample No. 3 using the method provided by this invention cannot meet the standard for electronic grade sulfuric acid.

[0071] Example 5

[0072] The method and steps are the same as in Example 3, except that the resin in step (3) is S910. After processing in steps (3) and (4), the results are as follows:

[0073] Table 6. Detection results of sample 5 in Example 5

[0074]

[0075] As can be seen from Example 5 and Table 6, the sulfuric acid obtained from waste sulfuric acid sample No. 3 using the method provided by this invention cannot meet the standard for electronic grade sulfuric acid.

[0076] Example 6

[0077] The method and steps are the same as in Example 3, except that the resin used in step (3) is a mixed resin (the volume ratio of MTS9500 and PAD600 is 5:1). After the treatment in steps (3) and (4), the results are as follows:

[0078] Table 7. Detection results of sample 6 in Example 6

[0079]

[0080]

[0081] As can be seen from Example 6 and Table 7, the sulfuric acid obtained from waste sulfuric acid sample No. 3 using the method provided by this invention cannot meet the standard for electronic grade sulfuric acid.

[0082] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for deep purification of waste sulfuric acid in the semiconductor industry, characterized in that, Includes the following steps: (1) The recovered waste sulfuric acid is heated to 50~100℃, and a catalyst is added to promote the decomposition of hydrogen peroxide in the waste sulfuric acid. Under the synergistic effect of the catalyst and hydrogen peroxide, the metal impurities in the waste sulfuric acid form intermediate oxidation products that are conducive to resin adsorption. At the same time, the oxygen and acid mist tail gas in the reaction process are collected and treated harmlessly. The catalyst is a combination of copper wire and zeolite, copper wire, or a combination of copper wire and copper oxide. (2) When the concentration of hydrogen peroxide in the waste sulfuric acid from step (1) is detected to be ≤0.002%, the reaction is stopped, and the waste sulfuric acid is cooled to 25~45℃; (3) At room temperature, the waste sulfuric acid from step (2) is subjected to metal impurities by mixed resin and samples are taken for analysis. The resin used is a mixed resin bed of two or more of the following types of resins: UPW650, C160, S910, ZGA307FM, S960, S985, and RCS81. (4) After removing impurities in step (3), the sulfuric acid is evaporated and concentrated at 100~200℃ for 3-6 hours to obtain high-purity sulfuric acid product. At the same time, the tail gas in the reaction process is collected and treated harmlessly.

2. The method for deep purification of waste sulfuric acid in the semiconductor industry according to claim 1, characterized in that, The concentration of the recovered waste sulfuric acid in step (1) is 60-85%.

3. The method for deep purification of waste sulfuric acid in the semiconductor industry according to claim 1, characterized in that, The heating temperature of the waste sulfuric acid in step (1) is 50~100℃.

4. The method for deep purification of waste sulfuric acid in the semiconductor industry according to claim 1, characterized in that, The exhaust gas mentioned in step (1) is absorbed countercurrently using alkaline solution.

5. The method for deep purification of waste sulfuric acid in the semiconductor industry according to claim 1, characterized in that, Repeat step (2) and monitor the concentration of hydrogen peroxide in the waste sulfuric acid in real time until the concentration of hydrogen peroxide in the waste sulfuric acid is ≤0.002%.

6. The method for deep purification of waste sulfuric acid in the semiconductor industry according to claim 1, characterized in that, In step (3), the resin needs to be washed repeatedly with ultrapure water 15-30 times.

7. The method for deep purification of waste sulfuric acid in the semiconductor industry according to claim 1, characterized in that, In step (3), the flow rate into the resin tower is 1~5 BV / min, and the purification time is 60~150 min.

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