Method for purifying and regenerating sulfur dioxide ionic liquid and application

Abstract

The invention belongs to the technical field of sulfuric acid tail gas treatment, and particularly relates to a method for purifying and regenerating sulfur dioxide ionic liquid and application. The method for purifying and regenerating the sulfur dioxide ionic liquid comprises the following steps: carrying out oxidation treatment on the sulfur dioxide ionic liquid, and filtering to obtain the pretreated sulfur dioxide ionic liquid; acidizing the extracted organic phase to obtain an acidized extracted organic phase; mixing the pretreated sulfur dioxide ionic liquid and the acidified extraction organic phase, extracting and separating to obtain purified sulfur dioxide ionic liquid and an impurity-loaded extraction organic phase; the extraction organic phase comprises an amine extraction agent, an acidic phosphate extraction agent and a diluent in percentage by volume; the amine extraction agent comprises at least one of trioctyl decyl tertiary amine and trioctylamine; and the acidic phosphate ester extraction agent comprises 2-ethylhexyl phosphoric acid-2-ethylhexyl ester. According to the method, harmful elements F, Cl and Fe can be effectively removed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sulfuric acid tail gas treatment, and particularly relates to a method for purifying and regenerating sulfur dioxide ionic liquid and application. BACKGROUND

[0002] In the pyrometallurgical process, sulfuric ore is used as the main raw material, and sulfur dioxide gas is generated after pyrometallurgical treatment. Sulfur dioxide is a harmful gas without color and with strong irritating odor, and is one of the important atmospheric pollutants. The existing desulfurization process mainly includes wet desulfurization, dry desulfurization and semi-dry desulfurization. Wet desulfurization mainly includes calcium flue gas desulfurization, double alkali method, magnesium oxide method, ammonia absorption method and the like. The calcium desulfurization mainly produces CaSO4 precipitate, and the pipeline is prone to fouling and has low comprehensive efficiency. In the ammonia desulfurization, there are problems such as ammonia supply transportation explosion prevention and limited use of ammonium sulfate. In order to improve the shortcomings of the above methods, new desulfurization methods such as biological method, urea method, organic amine regeneration method and ionic liquid flue gas desulfurization method have been applied.

[0003] The ionic liquid flue gas desulfurization technology gradually becomes an important desulfurization process technology due to the advantages of environmental protection, renewability and structure controllability. However, in actual production application, high dust content in flue gas, poor front-end washing effect or insufficient ionic liquid resolution may cause ionic liquid to precipitate sulfur, which seriously affects the stable operation of the ionic liquid. Especially in the non-ferrous smelting process, the sulfur dioxide flue gas has high dust content, the inlet concentration is uneven, and the flue gas which is not completely purified in the front end enters the ionic liquid absorption section, thereby dissolving F, Cl or other impurity ions into the ionic liquid, which is continuously accumulated in the ionic liquid, and finally leads to performance degradation.

[0004] The existing ionic liquid desulfurization system usually has a refrigeration crystallization desalination regeneration and APU ion exchange resin. The impurity F, Cl ions enter the ionic liquid, and when encountering acid, form strong corrosive hydrofluoric acid and hydrochloric acid, causing corrosion of the stainless steel filler in the resolution tower. The generated iron ions enter the ionic liquid, causing poisoning of the APU resin, performance degradation, and even directly leading to failure, indirectly causing an increase in sulfate in the ionic liquid. When the thiosulfate is too high, sulfur is precipitated when encountering acid, which blocks the heat exchanger and directly causes the system to shut down for processing. The existing refrigeration desalination and APU process cannot solve the problem of removal of F, Cl and Fe ions. In order to control the fluorine and chlorine in the ionic liquid, a fluorine and chlorine adsorption resin device is usually added to control the fluorine and chlorine ion concentration in the existing technology. However, in actual production, when the adsorption capacity decreases and the process control is improper, the fluorine and chlorine ions will exceed the standard, causing corrosion and further worsening the operation of the exchange resin, and even directly leading to the failure of the device. If the problem cannot be solved for a long time, the ionic liquid of the system has to be replaced, which causes production shutdown, increases production cost and poses a serious environmental risk.

[0005] Therefore, it is of great significance to provide a method for purifying and regenerating sulfur dioxide ionic liquid that can effectively remove the harmful elements F, Cl, and Fe in sulfur dioxide ionic liquid without introducing other harmful cations. Summary of the Invention

[0006] The present invention aims to solve one or more technical problems existing in the above-mentioned prior art and to provide at least a beneficial alternative. Specifically, the present invention provides a method for purifying and regenerating sulfur dioxide ionic liquid, which can effectively remove the harmful elements F, Cl, and Fe in the sulfur dioxide ionic liquid without introducing other harmful cations.

[0007] The inventive concept of the present invention is that the present invention pre-treats the sulfur dioxide ion liquid by oxidation. Due to the presence of SO2 in the sulfur dioxide ion liquid, Fe ions are mainly Fe 2+ Exist, through oxidation to Fe 2+ becomes Fe 3+ After that, the extraction rate of Fe is improved, and then the extraction organic phase of a specific type and ratio is used to extract it, which can significantly reduce the content of F, Cl, and Fe in the sulfur dioxide ion liquid, and effectively remove the harmful elements F, Cl, and Fe without introducing other harmful cations. The method is simple and efficient.

[0008] Therefore, a first aspect of the present invention provides a method for purifying and regenerating sulfur dioxide ionic liquid.

[0009] Specifically, the method for purifying and regenerating sulfur dioxide ionic liquid comprises the following steps:

[0010] (1) performing oxidation treatment on the sulfur dioxide ion liquid and filtering to obtain a pretreated sulfur dioxide ion liquid; performing acidification treatment on the extracted organic phase to obtain an acidified extracted organic phase;

[0011] (2) mixing the pretreated sulfur dioxide ion liquid obtained in step (1) with the acidified extraction organic phase, extracting, and separating to obtain a purified sulfur dioxide ion liquid;

[0012] The extraction organic phase includes an amine extractant, an acidic phosphate extractant and a diluent;

[0013] The amine extractant includes at least one of trioctyldecyl tertiary amine (N235) and trioctylamine (TOA); the acidic phosphate extractant includes 2-ethylhexyl phosphate-2-ethylhexyl ester (P507).

[0014] Preferably, in step (1), the sulfur dioxide ion liquid is oxidized by using an oxidant.

[0015] Preferably, the oxidant comprises hydrogen peroxide.

[0016] Preferably, the temperature of the oxidation treatment is 25-65° C., and the time of the oxidation treatment is 0.5-2.0 h; further preferably, the temperature of the oxidation treatment is 30-60° C., and the time of the oxidation treatment is 0.5-1.5 h.

[0017] Preferably, in step (1), the extracted organic phase is acidified using an acid agent.

[0018] Preferably, the acid agent includes sulfuric acid; further preferably, the sulfuric acid is dilute sulfuric acid.

[0019] Preferably, the concentration of the dilute sulfuric acid is 45-110 g / L; further preferably, the concentration of the dilute sulfuric acid is 50-100 g / L.

[0020] Preferably, the acidification treatment time is 3-7 minutes; further preferably, the acidification treatment time is 4-6 minutes; further preferably, the acidification treatment time is 5 minutes.

[0021] Preferably, in step (1), the volume concentration of the sulfur dioxide ionic liquid is 16-28%; further preferably, the volume concentration of the sulfur dioxide ionic liquid is 18-25%.

[0022] Preferably, in the sulfur dioxide ion liquid, SO4 2- The concentration is 55-120g / L; further preferably, in the sulfur dioxide ion liquid, SO4 2- The concentration is 60-110g / L.

[0023] Preferably, the impurities in the sulfur dioxide ionic liquid include at least one of fluorine, chlorine and iron.

[0024] Preferably, the molar ratio of the oxidant to the Fe element in the sulfur dioxide ionic liquid is (1.3-3.3):1; further preferably, the molar ratio of the oxidant to the Fe element in the sulfur dioxide ionic liquid is (1.5-3):1.

[0025] Preferably, during the acidification treatment, the volume ratio of the extracted organic phase to the acid agent is 1:(0.8-1.2); further preferably, during the acidification treatment, the volume ratio of the extracted organic phase to the acid agent is 1:(0.9-1.1); even further preferably, during the acidification treatment, the volume ratio of the extracted organic phase to the acid agent is 1:1.

[0026] Preferably, the extraction organic phase comprises, by volume percentage, 22-38% of an amine extractant, 8-22% of an acidic phosphate extractant, and 40-70% of a diluent.

[0027] Preferably, the extraction organic phase comprises, in volume percentage, 25-35% of amine extractant, 10-20% of acidic phosphate extractant, and 45-65% of diluent.

[0028] Preferably, the diluent comprises at least one of sulfonated kerosene and light white oil.

[0029] Preferably, in step (2), the volume ratio of the acidified extraction organic phase to the pretreated sulfur dioxide ionic liquid is (0.9-5.5):1; further preferably, the volume ratio of the acidified extraction organic phase to the pretreated sulfur dioxide ionic liquid is (1-5):1.

[0030] Preferably, in step (2), the temperature of the mixing is 23-70°C, and the time of the mixing is 2-17 min; further preferably, the temperature of the mixing is 25-65°C, and the time of the mixing is 2-15 min.

[0031] Preferably, in step (2), the number of stages of the extraction is 1-5 stages.

[0032] Preferably, in step (2), after the separation, a loaded impurity extraction organic phase is obtained, the loaded impurity extraction organic phase is mixed with a stripping agent, stripping is performed to obtain a regenerated organic phase, and the regenerated organic phase is recycled.

[0033] Preferably, the temperature of the mixing is 23-70°C, and the time of the mixing is 2-17 min; further preferably, the temperature of the mixing is 25-65°C, and the time of the mixing is 2-15 min.

[0034] Preferably, the volume ratio of the loaded impurity extraction organic phase to the stripping agent is (0.9-11):1; further preferably, the volume ratio of the loaded impurity extraction organic phase to the stripping agent is (1-10):1.

[0035] Preferably, the stripping agent comprises sulfuric acid; further preferably, the stripping agent comprises dilute sulfuric acid.

[0036] Preferably, the concentration of the dilute sulfuric acid is 75-270 g / L; further preferably, the concentration of the dilute sulfuric acid is 80-250 g / L.

[0037] Preferably, the number of stages of the stripping is 1-5 stages.

[0038] Preferably, the regenerated organic phase is washed with a washing agent, and the volume ratio of the regenerated organic phase to the washing agent is (0.9-11):1; further preferably, the volume ratio of the regenerated organic phase to the washing agent is (1-10):1.

[0039] Preferably, the washing agent comprises water.

[0040] Preferably, the temperature of the washing is 23-60℃, and the time of the washing is 2-17min; further preferably, the temperature of the washing is 25-55℃, and the time of the washing is 2-15min.

[0041] Preferably, the number of the washing is 1-6.

[0042] Preferably, the pH of the washing liquid obtained after the washing is greater than 4.2.

[0043] The second aspect of the present application provides an application of the method for purifying and regenerating sulfur dioxide ionic liquid in the treatment of sulfuric acid tail gas.

[0044] Compared with the prior art, the technical scheme provided by the present application has the following beneficial effects:

[0045] (1) The present application can significantly reduce the content of F, Cl and Fe in the sulfur dioxide ionic liquid by first performing an oxidation pretreatment on the sulfur dioxide ionic liquid, and then performing extraction on the sulfur dioxide ionic liquid with a specific type and ratio of extraction organic phase, thereby achieving effective removal of harmful elements F, Cl and Fe, without introducing other harmful cations, and the method is simple and efficient.

[0046] (2) The loaded organic phase can be obtained by back extraction, and the regenerated organic phase can be recycled and reused.

[0047] (3) The method of the present application is simple and efficient, and as a treatment measure, it can be directly connected in parallel in the entire production system, and can be started and stopped at any time according to the needs, thereby playing a role in protecting the stable operation of the entire sulfur dioxide ionic liquid adsorption system. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 Figure 1 is a process flow diagram of the purification and regeneration of sulfur dioxide ionic liquid according to Embodiment 1 of the present application. DETAILED DESCRIPTION

[0049] In order to make those skilled in the art more clearly understand the technical scheme of the present application, the following examples are given for illustration. It should be pointed out that the following examples do not constitute a limitation on the scope of protection required by the present application.

[0050] The raw materials, reagents or devices used in the following examples, if not specifically stated, can be obtained from conventional commercial channels, or can be obtained by existing known methods.

[0051] Example 1

[0052] A method for purifying and regenerating a sulfur dioxide ion liquid comprises the following steps:

[0053] (1) Take 10000mL of sulfur dioxide ionic liquid. The composition of sulfur dioxide ionic liquid is shown in Table 1: 2+ Add hydrogen peroxide at a molar concentration of 1.5 times, slowly add it in batches to avoid violent reaction and overflow, stir the reaction for 30 minutes, filter it, and measure Fe 2+ <0.05g / L, a pretreated sulfur dioxide ion liquid is obtained;

[0054] (2) 30% N235, 20% P507, and 50% 260# oil were mixed by volume to obtain a total of 1350 mL, and the mixture was set aside to obtain an extracted organic phase. Then, 50 g / L dilute sulfuric acid was added and the mixture was mixed according to a phase O / A ratio of 1:1 (extracted organic phase: dilute sulfuric acid = 1350 mL: 1350 mL). The mixture was shaken in a constant temperature water bath shaker for 5 min for acidification, and the acidified extracted organic phase was obtained by clarification and separation.

[0055] (3) The acidified extracted organic phase obtained in step (2) and the pretreated sulfur dioxide ion liquid obtained in step (1) are mixed at a ratio of O / A of 3:1 (acidified extracted organic phase: pretreated sulfur dioxide ion liquid = 1350 mL: 450 mL), and the mixture is shaken in a constant temperature water bath oscillator for 15 minutes for clarification and separation. After two-stage extraction, a raffinate (i.e., purified sulfur dioxide ion liquid) and an impurity-loaded extracted organic phase are obtained; the purified sulfur dioxide ion liquid enters the absorption system absorption liquid storage tank;

[0056] (4) adding 100 g / L dilute sulfuric acid to the impurity-loaded extracted organic phase obtained in step (3), mixing them according to a ratio of O / A of 9:1 (impurity-loaded extracted organic phase: dilute sulfuric acid = 1350 mL: 150 mL), oscillating them in a constant temperature water bath oscillator for 15 min, clarifying and separating, and obtaining a stripping solution after two-stage stripping, while regenerating the extracted organic phase to obtain a regenerated organic phase; washing the regenerated organic phase with pure water, mixing them according to a ratio of O / A of 1:1 (regenerated organic phase: pure water = 1350 mL: 1350 mL), oscillating them in a constant temperature water bath oscillator for 15 min, clarifying and separating, and obtaining a washing solution, wherein the pH value of the washing solution is measured to be 4.5; the stripping solution enters the water treatment system; and the washing solution returns to the production system.

[0057] Example 1 Schematic diagram of the process flow of sulfur dioxide ion liquid purification and regeneration Figure 1 shown.

[0058] The components and contents of the sulfur dioxide ion liquid, the pretreated sulfur dioxide ion liquid, the raffinate, the stripping liquid, and the washing liquid in Example 1 are shown in Table 1.

[0059] Table 1: Composition and content of sulfur dioxide ionic liquid, pretreated sulfur dioxide ionic liquid, raffinate, stripping liquid, and washing liquid in Example 1

[0060] Element <![CDATA[F - (mg / L)]]> Cl - (mg / L) Fe 2+ (mg / L) Fe 3+ (mg / L) SO4 2- (g / L) Sulfur dioxide ionic liquid 3260 684 2033 0 129 Pretreated sulfur dioxide ionic liquid 3204 680 48 1980 116 Raffinate 159 98 48 50 116 Strip 8328.78 1640.68 0 5553 0 Wash 35 14 0 55 0

[0061] Example 2

[0062] A method for purifying and regenerating a sulfur dioxide ion liquid comprises the following steps:

[0063] (1) Take 10000mL of sulfur dioxide ionic liquid and calculate the Fe 2+ Add hydrogen peroxide at a molar concentration of 1.5 times, slowly add it in batches to avoid violent reaction and overflow, stir the reaction for 30 minutes, filter it, and measure Fe 2+ <0.05g / L, a pretreated sulfur dioxide ion liquid is obtained;

[0064] (2) The regenerated organic phase of Example 1 (30% N235, 20% P507, and 50% 260# oil) was mixed with the pretreated filtrate to be used at an O / A ratio of 3:1 (organic phase: aqueous phase = 1350 mL: 450 mL), and the mixture was shaken in a constant temperature water bath shaker for 15 min. After two-stage extraction, the raffinate (i.e., purified sulfur dioxide ion liquid) and the impurity-loaded organic phase were obtained after clarification and separation.

[0065] The components and contents of the sulfur dioxide ion liquid, the pretreated sulfur dioxide ion liquid, the raffinate, the stripping liquid, and the washing liquid in Example 2 are shown in Table 2.

[0066] Table 2: Composition and content of sulfur dioxide ion liquid and raffinate in Example 2

[0067]

[0068]

[0069] Comparative Example 1

[0070] The only difference between Comparative Example 1 and Example 1 is that in step (2) of Comparative Example 1, the proportions of the components in the extracted organic phase are N235 17%, P507 33% and 260# oil 50%, respectively. Others are the same as in Example 1.

[0071] The components and contents of the sulfur dioxide ion liquid, the pretreated sulfur dioxide ion liquid, the raffinate, the stripping liquid, and the washing liquid in Comparative Example 1 are shown in Table 3.

[0072] Table 3: Composition and content of sulfur dioxide ionic liquid, pretreated sulfur dioxide ionic liquid, raffinate, stripping liquid and washing liquid in Comparative Example 1

[0073] Element <![CDATA[F - (mg / L)]]> <![CDATA[Cl - (mg / L)]]> <![CDATA[Fe 2+ (mg / L)]]> <![CDATA[Fe 3+ (mg / L)]]> SO4 2- (g / L) Sulfur dioxide ionic liquid 3260 684 2033 0 129 Pretreated sulfur dioxide ionic liquid 3204 680 48 1980 116 Raffinate 902 495 48 1.71 116 Strip 6598 535 0 5353 0 Wash 31 10 0 61 0

[0074] Comparative Example 2

[0075] The main difference between Comparative Example 2 and Example 1 is that the sulfur dioxide ionic liquid of Comparative Example 2 is not subjected to oxidation treatment.

[0076] Specifically, the method for purifying and regenerating the sulfur dioxide ionic liquid of Comparative Example 2 includes the following steps:

[0077] (1) Take 1500 mL of the sulfur dioxide ionic liquid without pretreatment, and mix with the regenerated organic phase obtained in Example 1 according to the phase ratio O / A of 3:1 (regenerated organic phase:sulfur dioxide ionic liquid = 1350 mL:450 mL), oscillate in a constant temperature water bath oscillator for 15 min, clarify and separate, and after two-stage extraction, obtain the raffinate (i.e. the purified sulfur dioxide ionic liquid) and the impurity-loaded extraction organic phase;

[0078] (2) Add 250 g / L dilute sulfuric acid to the impurity-loaded extraction organic phase, mix according to the phase ratio O / A of 9:1 (impurity-loaded extraction organic phase:dilute sulfuric acid = 1350 mL:150 mL), oscillate in a constant temperature water bath oscillator for 15 min, clarify and separate, and after one-stage stripping, obtain the stripping liquid and the regenerated organic phase, wash the regenerated organic phase with pure water according to the phase ratio O / A of 1:1 (regenerated organic phase: pure = 1350 mL:1350 mL), oscillate in a constant temperature water bath oscillator for 15 min, clarify and separate, and obtain the washing liquid, and measure the pH value of the washing liquid to be 4.5.

[0079] The components and contents in the sulfur dioxide ionic liquid, the raffinate, the stripping liquid, and the washing liquid of Comparative Example 2 are shown in Table 4.

[0080] Table 4: Components and contents in the sulfur dioxide ionic liquid, the raffinate, the stripping liquid, and the washing liquid of Comparative Example 2

[0081]

[0082] Comparative Example 3

[0083] The difference between Comparative Example 3 and Example 2 is only that the proportion of each component in the extraction organic phase of Comparative Example 3 is N235 20%, P507 20%, and 260# oil 60%, and the extraction organic phase is subjected to acidification treatment, and the others are the same as Example 2.

[0084] The acidification process is as follows: the components are mixed to obtain an extracted organic phase, 50 g / L dilute sulfuric acid is added to the extracted organic phase, and the mixture is mixed according to a phase O / A ratio of 1:1 (extracted organic phase: dilute sulfuric acid = 1350 mL: 1350 mL), and the mixture is shaken in a constant temperature water bath shaker for 5 minutes, clarified and separated, and the acidified extracted organic phase is obtained.

[0085] The components and contents of the pretreated sulfur dioxide ion liquid and raffinate in Comparative Example 3 are shown in Table 5.

[0086] Table 5: Composition and content of the pretreated sulfur dioxide ion liquid and raffinate in Comparative Example 3

[0087]

[0088] Comparative Example 4

[0089] The only difference between Comparative Example 4 and Example 2 is that the proportions of the components in the extracted organic phase of Comparative Example 4 are 20% N235, 5% P507 and 75% 260# oil, and the extracted organic phase is acidified. Others are the same as in Example 2.

[0090] The acidification process is as follows: the components are mixed to obtain an extracted organic phase, 50 g / L dilute sulfuric acid is added to the extracted organic phase, and the mixture is mixed according to a phase O / A ratio of 1:1 (extracted organic phase: dilute sulfuric acid = 1350 mL: 1350 mL), and the mixture is shaken in a constant temperature water bath shaker for 5 minutes, clarified and separated, and the acidified extracted organic phase is obtained.

[0091] The components and contents of the pretreated sulfur dioxide ion liquid and the raffinate in Comparative Example 4 are shown in Table 6.

[0092] Table 6: Composition and content of the pretreated sulfur dioxide ion liquid and raffinate in Comparative Example 4

[0093] Element <![CDATA[F - (mg / L)]]> Cl - (mg / L)]]> <![CDATA[Fe 2+ (mg / L)]]> <![CDATA[Fe 3+ (mg / L)]]> Pretreated sulfur dioxide ionic liquid 3204 680 48 1980 Raffinate 1101 163 48 1610

[0094] Comparative Example 5

[0095] The only difference between Comparative Example 5 and Example 2 is that the proportions of the components in the extracted organic phase of Comparative Example 5 are 20% N235, 25% P507 and 55% 260# oil, and the extracted organic phase is acidified. Others are the same as in Example 2.

[0096] The acidification process is as follows: the components are mixed to obtain an extracted organic phase, 50 g / L dilute sulfuric acid is added to the extracted organic phase, and the mixture is mixed according to a phase O / A ratio of 1:1 (extracted organic phase: dilute sulfuric acid = 1350 mL: 1350 mL), and the mixture is shaken in a constant temperature water bath shaker for 5 minutes, clarified and separated, and the acidified extracted organic phase is obtained.

[0097] The components and contents of the pretreated sulfur dioxide ion liquid and the raffinate in Comparative Example 5 are shown in Table 7.

[0098] Table 7: Composition and content of the pretreated sulfur dioxide ion liquid and raffinate in Comparative Example 5

[0099] Element <![CDATA[F - (mg / L)]]> Cl - (mg / L)]]> <![CDATA[Fe 2+ (mg / L)]]> Fe 3+ (mg / L) <!-- 6 -->]]> Pretreated sulfur dioxide ionic liquid 3204 680 48 1980 Raffinate 1376 199 48 8

[0100] Comparative Example 6

[0101] The only difference between Comparative Example 6 and Example 2 is that the proportions of the components in the extracted organic phase of Comparative Example 6 are 40% N235, 5% P507 and 55% 260# oil, and the extracted organic phase is acidified. Others are the same as in Example 2.

[0102] The acidification process is as follows: the components are mixed to obtain an extracted organic phase, 50 g / L dilute sulfuric acid is added to the extracted organic phase, and the mixture is mixed according to a phase O / A ratio of 1:1 (extracted organic phase: dilute sulfuric acid = 1350 mL: 1350 mL), and the mixture is shaken in a constant temperature water bath shaker for 5 minutes, clarified and separated, and the acidified extracted organic phase is obtained.

[0103] The components and contents of the pretreated sulfur dioxide ion liquid and the raffinate in Comparative Example 6 are shown in Table 8.

[0104] Table 8: Composition and content of the pretreated sulfur dioxide ion liquid and raffinate in Comparative Example 6

[0105]

[0106]

[0107] Comparative Example 7

[0108] The only difference between Comparative Example 7 and Example 2 is that the proportions of the components in the extracted organic phase of Comparative Example 7 are 40% N235, 25% P507 and 35% 260# oil, and the extracted organic phase is acidified. The rest is the same as Example 2.

[0109] The acidification process is as follows: the components are mixed to obtain an extracted organic phase, 50 g / L dilute sulfuric acid is added to the extracted organic phase, and the mixture is mixed according to a phase O / A ratio of 1:1 (extracted organic phase: dilute sulfuric acid = 1350 mL: 1350 mL), and the mixture is shaken in a constant temperature water bath shaker for 5 minutes, clarified and separated, and the acidified extracted organic phase is obtained.

[0110] The components and contents of the pretreated sulfur dioxide ion liquid and the raffinate in Comparative Example 7 are shown in Table 9.

[0111] Table 9: Composition and content of the pretreated sulfur dioxide ion liquid and raffinate in Comparative Example 7

[0112] Element F - (mg / L)]]> <![CDATA[Cl - (mg / L)]]> <![CDATA[Fe 2+ (mg / L)]]> Fe 3+ (mg / L) Pretreated sulfur dioxide ionic liquid 3204 680 48 1980 Raffinate 485 28 48 762

[0113] Comparative Example 8

[0114] The only difference between Comparative Example 8 and Example 2 is that in the extracted organic phase of Comparative Example 8, N1923 is used in equal amounts to replace N235, and the extracted organic phase is acidified. Other steps are the same as in Example 2.

[0115] The acidification process is as follows: the components are mixed to obtain an extracted organic phase, 50 g / L dilute sulfuric acid is added to the extracted organic phase, and the mixture is mixed according to a phase O / A ratio of 1:1 (extracted organic phase: dilute sulfuric acid = 1350 mL: 1350 mL), and the mixture is shaken in a constant temperature water bath shaker for 5 minutes, clarified and separated, and the acidified extracted organic phase is obtained.

[0116] The components and contents of the pretreated sulfur dioxide ion liquid and the raffinate in Comparative Example 8 are shown in Table 10.

[0117] Table 10: Composition and content of the pretreated sulfur dioxide ion liquid and raffinate in Comparative Example 8

[0118] Element F - (mg / L)]]> Cl - (mg / L) Fe 2+ (mg / L)]]> <![CDATA[Fe 3+ (mg / L)]]> Pretreated sulfur dioxide ionic liquid 3204 680 48 1980 Raffinate 784 75 48 1711

[0119] Comparative Example 9

[0120] The only difference between Comparative Example 9 and Example 2 is that in the extracted organic phase of Comparative Example 9, P204 is used in equal amounts to replace P507, and the extracted organic phase is acidified. Other steps are the same as in Example 2.

[0121] The acidification process is as follows: the components are mixed to obtain an extracted organic phase, 50 g / L dilute sulfuric acid is added to the extracted organic phase, and the mixture is mixed according to a phase O / A ratio of 1:1 (extracted organic phase: dilute sulfuric acid = 1350 mL: 1350 mL), and the mixture is shaken in a constant temperature water bath shaker for 5 minutes, clarified and separated, and the acidified extracted organic phase is obtained.

[0122] The components and contents of the pretreated sulfur dioxide ion liquid and the raffinate in Comparative Example 9 are shown in Table 11.

[0123] Table 11: Composition and content of the pretreated sulfur dioxide ion liquid and raffinate in Comparative Example 9

[0124] Element <![CDATA[F - (mg / L)]]> <![CDATA[Cl - (mg / L)]]> Fe 2+ (mg / L) <![CDATA[Fe 3+ (mg / L)]]> Pretreated sulfur dioxide ionic liquid 3204 680 48 1980 Raffinate 346 60 48 591

[0125] For Example 1 and Comparative Example 1-2, - 、Cl - 、Fe 2+F, Cl, Fe 3+ The extraction rate and stripping rate of F - , Cl - , Fe 2+ , Fe 3+ are calculated, and the results are shown in Table 12.

[0126] The extraction rate = (the impurity content in the filtrate after pretreatment - the impurity content in the filtrate after extraction) / the impurity content in the filtrate after pretreatment * 100%; the impurity content in the filtrate after pretreatment is the impurity content in the sulfur dioxide ionic liquid after pretreatment, and the impurity content in the filtrate after extraction is the impurity content in the raffinate.

[0127] For example, the extraction rate of F - in Example 1 = (3204 - 159) / 3204 * 100% = 95.03%.

[0128] The stripping rate = the impurity content in the stripping liquid / ((the impurity content in the filtrate after pretreatment - the impurity content in the filtrate after extraction) / (the ratio of stripping to extraction)) * 100%.

[0129] For example: F - The stripping rate = 8328.78 / ((3204 - 159) / (9 / 3)) * 100% = 91.17%.

[0130] Table 12: The extraction rate and stripping rate of F - , Cl - , Fe 2+ , Fe 3+ in Example 1, Comparative Examples 1-2, and the extraction rate of F - , Cl - , Fe 2+ , Fe 3+ in Comparative Examples 3-9

[0131]

[0132]

[0133] As can be seen from Table 12, the purification method of the present application has good extraction rates for F, Cl and Fe, can significantly reduce the content of F, Cl and Fe in the sulfur dioxide ionic liquid, and realizes effective removal of harmful elements F, Cl and Fe.

[0134] The proportion of N235 and P507 in the extraction organic phase of Comparative Example 1 is not within the volume fraction range, the proportion of N235 is too small, and the proportion of P507 is too large, so that the extraction rates of F and Cl in Comparative Example 1 are significantly lower than those in Example 1.

[0135] The proportion of N235 in the extraction organic phase of Comparative Example 3 is not within the volume fraction range, and the proportion is too small, so the extraction rates of F and Cl in Comparative Example 3 are obviously lower than those in Example 2.

[0136] The proportions of N235, P507 and 260# oil in the extraction organic phase of Comparative Example 4 are not within the volume fraction range, the proportion of N235 is too small, the proportion of P507 is too small, and the proportion of 260# oil is too large, so the extraction rates of F, Cl and Fe in Comparative Example 4 are obviously lower than those in Example 2. 3+

[0137] The proportions of N235 and P507 in the extraction organic phase of Comparative Example 5 are not within the volume fraction range, the proportion of N235 is too small, and the proportion of P507 is too large, so the extraction rates of F and Cl in Comparative Example 5 are obviously lower than those in Example 2.

[0138] The proportions of N235 and P507 in the extraction organic phase of Comparative Example 6 are not within the volume fraction range, the proportion of N235 is too large, and the proportion of P507 is too small, so the extraction rates of F and Fe in Comparative Example 6 are obviously lower than those in Example 1. 3+

[0139] The proportions of N235, P507 and 260# oil in the extraction organic phase of Comparative Example 7 are not within the volume fraction range, the proportion of N235 is too large, the proportion of P507 is too large, and the proportion of 260# oil is too small, so the extraction rates of F and Fe in Comparative Example 7 are obviously lower than those in Example 1. 3+

[0140] As can be seen from Comparative Examples 1, 3-7, N235, P507 and 260# oil in the extraction organic phase need to be mixed in a specific proportion, and any one component exceeding the dosage range will reduce the removal effect of impurities.

[0141] The sulfur dioxide ionic liquid in Comparative Example 2 is not subjected to oxidation treatment, so the extraction rate of Fe in Comparative Example 2 is obviously lower than the extraction rate of Fe in Example 1. 3+ 3+ The extraction rate of Fe in Example 1. 3+

[0142] Comparative Example 8 uses N1923 to replace N235 in an equal amount, so the extraction rates of F, Cl and Fe in Comparative Example 8 are obviously lower than those in Example 2.

[0143] Comparative Example 9 uses P204 to replace P507 in an equal amount, so the extraction rates of F and Fe in Comparative Example 9 are obviously lower than those in Example 2. 3+

[0144] ​​​​​​It can be seen from Comparative Examples 8-9 that a specific combination of amine extractants and acidic phosphate extractants is required to better improve the extraction effect of impurities and achieve purification and regeneration of sulfur dioxide ion liquid.

[0145] In summary, the present invention first performs oxidation pretreatment on the sulfur dioxide ion liquid and then extracts it using an extraction organic phase of a specific type and ratio, so as to significantly reduce the content of F, Cl, and Fe in the sulfur dioxide ion liquid and achieve effective removal of the harmful elements F, Cl, and Fe.

[0146] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for purifying and regenerating sulfur dioxide ionic liquid, characterized in that: The following steps are involved: (1) performing oxidation treatment on the sulfur dioxide ion liquid and filtering to obtain a pretreated sulfur dioxide ion liquid; performing acidification treatment on the extracted organic phase to obtain an acidified extracted organic phase; (2) mixing the pretreated sulfur dioxide ion liquid obtained in step (1) with the acidified extracted organic phase, extracting, and separating to obtain a purified sulfur dioxide ion liquid; The extraction organic phase includes an amine extractant, an acidic phosphate extractant and a diluent; The amine extractant includes at least one of trioctyldecyl tertiary amine and trioctylamine; the acidic phosphate extractant includes 2-ethylhexyl phosphate-2-ethylhexyl ester.

2. The method according to claim 1, characterized in that In step (1), the sulfur dioxide ion liquid is oxidized by an oxidant; and / or the oxidation treatment temperature is 25-65° C., and the oxidation treatment time is 0.5-2.0 h; and / or the extracted organic phase is acidified by an acid agent; and / or the acidification treatment time is 3-7 min.

3. The method according to claim 2, characterized in that In the sulfur dioxide ion liquid, SO4 2- The concentration is 55-120 g / L; and / or, the impurities in the sulfur dioxide ionic liquid include at least one of fluorine, chlorine and iron.

4. The method according to claim 2, characterized in that The oxidant includes hydrogen peroxide; and / or the acid includes sulfuric acid; and / or, by volume percentage, the extraction organic phase includes 22-38% of an amine extractant, 8-22% of an acidic phosphate extractant, and 40-70% of a diluent; and / or, the diluent includes at least one of sulfonated kerosene and light white oil.

5. The method according to claim 3, characterized in that The molar ratio of the oxidant to the Fe element in the sulfur dioxide ionic liquid is (1.3-3.3):1; and / or, during the acidification treatment, the volume ratio of the extracted organic phase to the acid agent is 1:(0.8-1.2).

6. The method according to claim 1, characterized in that In step (2), the volume ratio of the acidified extraction organic phase to the pretreated sulfur dioxide ionic liquid is (0.9-5.5):1; and / or the mixing temperature is 23-70°C, the mixing time is 2-17 minutes; and / or the number of extraction stages is 1-5.

7. The method according to claim 1, characterized in that In step (2), after the separation, an extracted organic phase loaded with impurities is obtained. The extracted organic phase loaded with impurities is mixed with a stripping agent, stripped, and a regenerated organic phase is obtained for recycling.

8. The method according to claim 7, characterized in that The volume ratio of the impurity-loaded extraction organic phase and the stripping agent is (0.9-11):1; and / or the stripping agent includes sulfuric acid; and / or the mixing temperature is 23-70°C, and the mixing time is 2-17 minutes; and / or the number of stripping stages is 1-5.

9. The method according to claim 7, characterized in that The regenerated organic phase is washed with a detergent, wherein the volume ratio of the regenerated organic phase to the detergent is (0.9-11):1; and / or the number of washing stages is 1-6; and / or the washing temperature is 23-60° C., and the washing time is 2-17 min.

10. Use of the method according to any one of claims 1 to 9 in the treatment of sulfuric acid tail gas.

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