A method for resourceful treatment of desulfurization wastewater

Abstract

The present application relates to a kind of desulfurization wastewater resource processing method.The method comprises: adding water treatment filler to desulfurization wastewater;Distillation desulfurization wastewater, subsection collection condensate, heating distillation to the volume of desulfurization wastewater reduces to 70% of initial volume, obtain the first stage condensate for recycling dilute ammonia liquor;Continue heating distillation to the volume of desulfurization wastewater from 70% of initial volume reduces to 20%, obtain the second stage condensate;Continue heating distillation to the volume of desulfurization wastewater from 20% of initial volume reduces to 5% or to evaporate dry, obtain the third stage condensate, second, third stage condensate is used for recycling dilute ammonia liquor or reflux to the original solution of desulfurization wastewater and is treated in cycle or treatment up to standard reuse;Remaining residue is detoxified, and the resource of desulfurization wastewater is processed.The present application solves the problems that the existing desulfurization wastewater treatment method is difficult to realize resource recycling, low processing efficiency, high cost, easy to cause secondary pollution and difficult to discharge up to standard.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resource recovery, and particularly relates to a resource treatment method of desulfurization wastewater. BACKGROUND

[0002] Lithium, as a strategic and key mineral resource in the 21st century, has become the core driving force for global energy transformation and emerging industry development due to its unique properties as an "energy metal" and a "green high-energy metal". Among them, the industrialized processing technology of lepidolite concentrate mainly includes sulfate roasting method, sulfate ripening method and other systems. The limestone sintering process has gradually withdrawn from the industrial application field because it needs to be roasted at high temperature (about 1000℃) after mixing with calcium carbonate as a roasting aid and lepidolite, which has the defects of high energy consumption and large material processing capacity. In contrast, the sulfate roasting system can realize efficient lithium extraction at a relatively low roasting temperature (about 850℃) by introducing potassium sulfate, sodium sulfate or calcium sulfate as an aid, and has become a mainstream technical solution with industrial application value.

[0003] As an important process for lithium salt production, the environmental pollutants generated during the operation of the sulfate roasting method have attracted great attention. The sulfur-containing flue gas (SO2 concentration about 0.3%) and suspended particulate matter released by the process will cause serious environmental problems if not effectively treated. For the tunnel kiln flue gas generated in the roasting process, modern lithium salt enterprises have established a multi-level collaborative management system. Firstly, energy cascade utilization is realized through a dry kiln waste heat recovery device, and then deep purification is carried out by using a cyclone dust collector combined with an absorption tower, so that the flue gas temperature is reduced from the initial 450℃ to below 120℃. The subsequent configuration of a primary fluoride removal system (Ca(OH)2 slurry spraying) and two-stage alkali washing devices can control the SO2 emission concentration to less than 35mg / m 3 At the same time, gaseous pollutants such as HF are effectively captured. The sulfuric acid mist waste gas generated in the desulfurization section is neutralized by an alkali spraying tower (NaOH solution concentration 5-8%), and the removal rate of the system is more than 95%. The desulfurization wastewater is generated in the wet sodium alkali desulfurization link, and the hazards of the desulfurization wastewater include: on the environmental level, the addition of urea in the sulfate roasting process will cause eutrophication; on the ecological level, heavy metals (mercury, lead, thallium) will be enriched through the food chain, and fluorides will destroy the soil structure, leading to salinization; on the health level, pollutants have the risk of causing cancer and teratogenesis, threatening human nervous and organ functions; on the industrial level, high salt corrosion accelerates equipment wear and tear, and operation and maintenance costs rise. Therefore, effective treatment of desulfurization wastewater is a problem that needs to be solved.

[0004] Currently, the main treatment methods for desulfurization wastewater include chemical precipitation method, membrane treatment method, etc. However, they all have obvious technical defects. The process flow of the chemical precipitation method mainly includes four links of neutralization reaction, flocculation and sedimentation, gravity sedimentation and clarification separation. However, it has the problems that by-products are difficult to be recycled and resourceized, and secondary pollution is easily caused. The membrane treatment method mainly includes membrane separation method and electrodialysis method. The membrane separation technology system includes microfiltration, ultrafiltration, nanofiltration and reverse osmosis, etc. It can effectively intercept calcium and magnesium ions, colloids and heavy metals and other pollutants. However, there are also significant problems: by-products have not been effectively recycled and resourceized, high-pressure operation leads to high energy consumption, the increasing pressure difference caused by membrane pollution needs to be cleaned by chemical agents such as citric acid and sodium hypochlorite, which produces the risk of secondary pollution, and the replacement and maintenance cost of the membrane assembly is high. The electrodialysis method realizes concentration through the alternating arrangement of anion and cation exchange membranes and a direct current field, but also does not realize resource recycling and application, and the membrane pollution problem is significant during operation: the deposition of organic / inorganic pollutants leads to the increase of membrane resistance, and the treatment flow is reduced by about 28%, which needs to be cleaned regularly or the membrane assembly needs to be replaced to maintain the performance, thereby increasing the operation and maintenance cost and restricting its industrialization promotion. SUMMARY

[0005] Therefore, the present application aims to provide a resource treatment method for desulfurization wastewater, so as to solve the problems that the existing treatment methods for desulfurization wastewater are difficult to realize resource recycling and utilization, and also can solve the problems that the existing treatment methods for desulfurization wastewater have low treatment efficiency, high cost, are easy to cause secondary pollution and are difficult to meet the discharge standard.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] A resource treatment method for desulfurization wastewater, comprising the following steps:

[0008] Adding a water treatment filler to the desulfurization wastewater, the water treatment filler being selected from at least one of artificial zeolite, coconut shell activated carbon and glass beads;

[0009] Heating and distilling the desulfurization wastewater, and collecting condensed liquid in stages, the collection of the condensed liquid including at least the following three stages;

[0010] In the first stage, heating and distillation is carried out until the volume of the desulfurization wastewater is reduced to 70% of the initial volume, and the generated condensed liquid is collected to obtain a first-stage condensed liquid, which is used for recycling dilute ammonia water;

[0011] In the second stage, heating and distillation is continued until the volume of the desulfurization wastewater is reduced from 70% to 20% of the initial volume, and the generated condensed liquid is collected to obtain a second-stage condensed liquid, which is used for recycling dilute ammonia water or treated to meet the standard and used as industrial water;

[0012] In the third stage, the heating and distillation are continued until the volume of the desulfurization wastewater is reduced from 20% to 5% of the initial volume or until the desulfurization wastewater is evaporated, and the generated condensate is collected to obtain a third-stage condensate, which is used to recover dilute ammonia water or is returned to the original desulfurization wastewater to achieve cyclic treatment;

[0013] The remaining residue is returned to the desulfurization wastewater for cyclic treatment if it is liquid, or is converted to harmless treatment if it is solid, to achieve resourceful treatment of the desulfurization wastewater.

[0014] According to the above technical means, through the way of segmented distillation, the condensate of the first stage and the second stage can effectively recover dilute ammonia water. Dilute ammonia water is a valuable chemical that can be used for industrial production or other purposes, thereby realizing the reuse of resources and reducing waste. The condensate of the second stage is used to recover dilute ammonia water or can be reused as industrial water after treatment. The condensate of the third stage is used to recover dilute ammonia water or is returned to the original desulfurization wastewater to achieve cyclic treatment. This not only reduces the demand for fresh water resources, but also reduces the water cost of enterprises, while reducing the amount of wastewater discharge. It effectively solves the problem that the existing desulfurization wastewater treatment method is difficult to achieve resourceful recycling, and also solves the problems of low treatment efficiency, high cost, easy secondary pollution, and difficulty in reaching the standard for discharge.

[0015] By dividing the distillation process into three stages, the wastewater can be treated according to the characteristics of different stages. For example, the first stage mainly recovers high-concentration ammonia water, and the second and third stages can recover low-concentration ammonia water or be reused after treatment or be returned to the original desulfurization wastewater to achieve cyclic treatment. This segmented treatment method improves the efficiency of resource recovery and avoids the limitations of single treatment methods. At the same time, by adding water treatment fillers such as artificial zeolite, activated carbon, and glass beads, the distillation effect of the wastewater can be improved, and the distillation efficiency can be improved. These fillers can adsorb impurities in the wastewater, reduce impurity interference during distillation, and improve the purity of the condensate. Through resourceful treatment, most of the wastewater is recycled, reducing the amount of wastewater discharge, thereby reducing the cost of sewage treatment. The above method not only solves the problem of desulfurization wastewater treatment, but also realizes the recycling of resources, in line with the concept of sustainable development. Through resourceful treatment, enterprises can balance environmental protection and economic benefits. When the remaining residue is solid, the mass and volume are very small, so it is directly entrusted to a third-party qualified company for harmless treatment, avoiding the possible secondary pollution caused by improper treatment. This treatment method meets the environmental protection requirements and reduces the pressure on the environment.

[0016] Preferably, the method for recovering ammonia water using the first-stage condensate includes the following steps:

[0017] The water treatment filler is added to the first stage condensate, and then at least one heating distillation is continued to obtain dilute ammonia water and a first residual liquid, which is returned to the first stage condensate to realize cyclic treatment. By adding the water treatment filler to the first stage condensate, the release rate of ammonia nitrogen is effectively improved, thereby improving the content of ammonia nitrogen in the condensate, and further providing convenience for the preparation of high-concentration ammonia water, while reducing the ammonia nitrogen in the remaining residue and reducing the difficulty of subsequent treatment.

[0018] When the ammonia nitrogen concentration in the distillation liquid obtained after heating distillation of the first stage condensate does not meet the requirement of dilute ammonia water, secondary, tertiary and more heating distillation methods can be performed. The ammonia nitrogen concentration in the distillation liquid after multiple cycles of heating distillation gradually increases, while the related salinity and thallium content of heavy metals continuously decrease, thereby meeting the requirement of dilute ammonia water.

[0019] Preferably, the water treatment filler is added to the first stage condensate, and the salinity is increased, and then at least one heating distillation is performed to obtain dilute ammonia water and a first residual liquid. By adding the water treatment filler to the first stage condensate and increasing the salinity, the release rate of ammonia nitrogen is further effectively improved.

[0020] Preferably, the salinity of the first stage condensate is increased to 1.55% by adding sodium chloride.

[0021] Preferably, after the second stage condensate is treated by the aeration process with the artificial zeolite, it is used as industrial water.

[0022] Preferably, during the aeration process treatment, air treatment is performed, the air flow rate is 1.5 L / min, and the aeration process treatment time is 14 h.

[0023] Preferably, the second stage condensate is used for recycling dilute ammonia water, and the third stage condensate is used for recycling dilute ammonia water, which comprises: mixing the second stage condensate and the third stage condensate, then adding artificial zeolite and increasing the salinity, and then continuing at least one heating distillation to obtain dilute ammonia water and a second residual liquid, which is returned to the previous stage (i.e., the mixed solution of the second stage condensate and the third stage condensate) or used as industrial water after treatment.

[0024] Preferably, the salinity is increased to 1.55% by adding sodium chloride.

[0025] Preferably, after the second residual liquid is treated to meet the standard, it is used as industrial water by adding artificial zeolite to the second residual liquid and treating it by the aeration process to meet the standard.

[0026] Preferably, the addition amount of artificial zeolite in the desulfurization wastewater is 40-160 mg / L.

[0027] Preferably, the desulfurization wastewater is desulfurization wastewater generated in a desulfurization step of a wet sodium alkali method for producing lithium salt by a sulfate roasting method.

[0028] The desulfurization wastewater has a salt concentration of 1.55-8.83%, and the salt is mainly sodium sulfate, a fluoride concentration of 1300-4600 mg / L, a heavy metal Tl concentration of 1600-2900 μg / L, a pH value of 6.42-7.98, an ammonia nitrogen (NH3-N) concentration of 900-1200 mg / L, and a COD concentration of 100-44000 mg / L.

[0029] Preferably, when the ammonia nitrogen concentration in the desulfurization wastewater is 1200-13000 mg / L, water treatment fillers and an alkaline reagent are added to the desulfurization wastewater, and then the desulfurization wastewater is heated and distilled, and the condensate is collected in stages; the desulfurization wastewater is desulfurization wastewater generated in a desulfurization step of a wet sodium alkali method for producing lithium salt by a sulfate roasting method; the desulfurization wastewater has a salt concentration of 1.55-8.83%, a fluoride concentration of 1300-4600 mg / L, a heavy metal Tl concentration of 1600-2900 μg / L, a pH value of 6.42-7.98, and a COD concentration of 100-44000 mg / L.

[0030] Preferably, the alkaline reagent is selected from sodium hydroxide and / or calcium hydroxide.

[0031] Preferably, the water treatment fillers are selected from glass beads.

[0032] Preferably, the amount of glass beads added to the desulfurization wastewater is 40-160 mg / L.

[0033] Preferably, water treatment fillers and an alkaline reagent are added to the first-stage condensate, so that the pH value of the first-stage condensate is greater than 10, and then the heating and distillation is continued at least once to obtain dilute ammonia water and a first residual liquid.

[0034] Preferably, the temperature of the heating and distillation is 100-130°C.

[0035] Preferably, the heating and distillation process is carried out using waste heat of a factory, so that waste heat is recycled and the processing cost is effectively reduced.

[0036] Preferably, in the heating and distillation process, the temperature of the condensate is less than or equal to 25°C.

[0037] Advantages of the present application:

[0038] The resource processing method of desulfurization wastewater of the present application first, through the way of fractional distillation, the condensate of the first stage and the second stage can effectively recover the dilute ammonia water, thereby realizing the reuse of resources and reducing waste. The condensate of the second stage and the third stage can be reused as industrial water after treatment. This not only reduces the demand for fresh water resources, but also reduces the water cost of enterprises, while reducing the wastewater discharge. By dividing the distillation process into three stages, the wastewater characteristics of different stages can be treated according to the characteristics of different stages. For example, the first stage mainly recovers high-concentration ammonia water, and the second and third stages can recover low-concentration ammonia water or be reused or recycled to the original solution of desulfurization wastewater after treatment. This segmented treatment method improves the efficiency of resource recovery and avoids the limitations of single treatment method. At the same time, by adding water treatment fillers such as artificial zeolite, activated carbon and glass beads, the distillation effect of wastewater can be improved, and the distillation efficiency can be improved. These fillers can adsorb impurities in wastewater, reduce impurity interference in the distillation process, and improve the purity of the condensate. In the field of wastewater resource recycling technology, it has popularization and application value. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The ammonia nitrogen concentration change result graph of the condensate of each stage of desulfurization wastewater and the solution after mixing the condensate of each stage;

[0040] Figure 2 The ammonia nitrogen concentration change result graph of the condensate of each stage of desulfurization wastewater and the solution after mixing the condensate of each stage;

[0041] Figure 3 The ammonia nitrogen concentration change result graph of the condensate of each stage of desulfurization wastewater and the solution after mixing the condensate of each stage;

[0042] Figure 4 The ammonia nitrogen concentration change result graph of the condensate of each stage of desulfurization wastewater and the solution after mixing the condensate of each stage;

[0043] Figure 5 The ammonia nitrogen concentration change result graph of the condensate of each stage of desulfurization wastewater and the solution after mixing the condensate of each stage;

[0044] Figure 6 The ammonia nitrogen concentration change result graph of the condensate of each stage of desulfurization wastewater and the solution after mixing the condensate of each stage;

[0045] Figure 7 The ammonia nitrogen concentration change result graph of the condensate of each stage of desulfurization wastewater and the solution after mixing the condensate of each stage;

[0046] Figure 8 The F -Graph showing the changes in concentration;

[0047] Figure 9 The effect of artificial zeolite dosage on the F content in the condensate and mixed solution of desulfurization wastewater at each stage - Graph showing the changes in concentration;

[0048] Figure 10 F in the condensate and mixed solution of high ammonia nitrogen desulfurization wastewater at each stage - Graph showing the changes in concentration;

[0049] Figure 11 To facilitate the reuse of artificial zeolite in the condensate and mixed solution of desulfurization wastewater at each stage, F - Graph showing the changes in concentration;

[0050] Figure 12 The graph shows the changes in salinity, TDS, conductivity, and pH in the condensate of desulfurization wastewater at each stage.

[0051] Figure 13 The graph shows the effect of artificial zeolite dosage on the salinity, TDS, conductivity and pH of the condensate at each stage.

[0052] Figure 14 The graph shows the changes in salinity, TDS, conductivity, and pH in the condensate of high ammonia nitrogen desulfurization wastewater at each stage.

[0053] Figure 15 The graph shows the changes in salinity, TDS, conductivity, and pH in the condensate of desulfurization wastewater at different stages with different pH values.

[0054] Figure 16 The graph shows the changes in TI concentration in the condensate of desulfurization wastewater at different stages.

[0055] Figure 17 The graph shows the effect of artificial zeolite dosage on the TI concentration in the condensate at each stage.

[0056] Figure 18 The graph shows the changes in TI concentration in the condensate and the mixed solution of high ammonia nitrogen desulfurization wastewater at each stage.

[0057] Figure 19 The graph shows the changes in TI concentration in the condensate and mixed solution of desulfurization wastewater at different pH stages.

[0058] Figure 20 The graph shows the effect of artificial zeolite dosage on COD concentration in condensate and mixed solution at each stage.

[0059] Figure 21 The graph shows the changes in COD concentration in the condensate and the mixed solution of high ammonia nitrogen desulfurization wastewater at each stage.

[0060] Figure 22 COD concentration change results chart of each stage condensate and mixed solution of desulfurization wastewater at different pH;

[0061] Figure 23 COD concentration change results chart of each stage condensate and mixed solution of zeolite recycling. DETAILED DESCRIPTION

[0062] The present application will be described in detail with reference to preferred embodiments. Other advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure herein. The present application can also be implemented or applied by other different specific embodiments, and various modifications or changes can be made to the details herein based on different views and applications without departing from the spirit of the present application. It should be understood that the preferred embodiments are only for illustrating the present application, but not for limiting the protection scope of the present application.

[0063] The desulfurization wastewater used in the following examples is from the wet sodium alkali desulfurization process in the production of lithium salt by the sulfate roasting method of lithium mica concentrate. The water quality characteristics of the desulfurization wastewater include: ① high salt content and complex ion composition, high salt concentration (1.55-8.83%), mainly sodium sulfate (generated by the reaction of desulfurizer NaOH and SO2), and high concentration of fluoride (1300-4600 mg / L, generated by NaF and Na2SiF6 from fluorine elements in the ore); ② heavy metal Tl concentration of 1600-2900 μg / L; ③ acidity and alkalinity, desulfurization wastewater pH fluctuates between 6.42-7.98, fluoride (such as HF) further aggravates acid corrosion, threatening equipment life; ④ NH3-N concentration of 900-13000 mg / L, COD concentration of 100-44000 mg / L.

[0064] Example 1

[0065] A resource utilization treatment method of desulfurization wastewater, comprising the following steps:

[0066] Artificial zeolite is added to the desulfurization wastewater, the addition amount of the artificial zeolite is 40 g / L, then heating distillation is carried out under the condition that the temperature is 120℃, and the condensate is collected in sections, the temperature of the condensing water used for collecting the condensate is 5℃, the initial concentration of NH3-N in the desulfurization wastewater is 914.88-931.05 mg / L, and the collection of the condensate includes the following three stages;

[0067] The first stage (i.e. the early stage of distillation in Table 1) includes three small stages, the first stage is heating distillation until the volume of desulfurization wastewater is reduced to 90% of the initial volume, and the condensed liquid produced is collected to obtain the first stage condensed liquid; the second stage is to continue heating distillation until the volume of desulfurization wastewater is reduced from 90% to 80% of the initial volume, and the condensed liquid produced is collected to obtain the second stage condensed liquid; the third stage is to continue heating distillation until the volume of desulfurization wastewater is reduced from 80% to 70% of the initial volume, and the condensed liquid produced is collected to obtain the third stage condensed liquid; the mixture of the first stage condensed liquid to the third stage condensed liquid is the first stage condensed liquid, and the first stage condensed liquid is used for recovering dilute ammonia water;

[0068] The second stage (i.e. the middle stage of distillation in Table 1) includes five small stages, the fourth stage is to continue heating distillation until the volume of desulfurization wastewater is reduced from 70% to 60% of the initial volume, and the condensed liquid produced is collected to obtain the fourth stage condensed liquid; the fifth stage is to continue heating distillation until the volume of desulfurization wastewater is reduced from 60% to 50% of the initial volume, and the condensed liquid produced is collected to obtain the fifth stage condensed liquid; and so on, to obtain the sixth stage condensed liquid, the seventh stage condensed liquid and the eighth stage condensed liquid; the mixture of the fourth stage condensed liquid to the eighth stage condensed liquid is the second stage condensed liquid;

[0069] The third stage (i.e. the late stage of distillation in Table 1) includes two small stages, the ninth stage is to continue heating distillation until the volume of desulfurization wastewater is reduced from 20% to 10% of the initial volume, and the condensed liquid produced is collected to obtain the ninth stage condensed liquid; the tenth stage is to continue heating distillation until the volume of desulfurization wastewater is reduced from 10% to 5% of the initial volume, and the condensed liquid produced is collected to obtain the tenth stage condensed liquid; the mixture of the ninth stage condensed liquid and the tenth stage condensed liquid is the third stage condensed liquid;

[0070] The remaining residue is liquid, which is returned to the desulfurization wastewater for recycling treatment, so as to realize the resource treatment of the desulfurization wastewater.

[0071] Table 1 Definition of distillation stages

[0072]

[0073] Example 2

[0074] In this embodiment, the artificial zeolite is replaced by coconut activated carbon, and the rest is the same as Example 1.

[0075] Example 3

[0076] In this embodiment, the artificial zeolite is replaced by glass beads, and the rest is the same as Example 1.

[0077] Example 4

[0078] A resourceful treatment method of desulfurization wastewater, comprising the following steps:

[0079] Artificial zeolite is added to the desulfurization wastewater, the addition amount of the artificial zeolite is 40 g / L, then heating distillation is carried out under the condition that the temperature is 120 ℃, and the condensate is collected in sections, the temperature of the condensing water used for collecting the condensate is 5 ℃, the initial concentration of NH3-N in the desulfurization wastewater is 914.885-931.05 mg / L, and the collection of the condensate includes the following three stages.

[0080] The first stage (i.e. the early stage of distillation in Table 1) includes three small stages, the first stage is heating distillation until the volume of the desulfurization wastewater is reduced to 90% of the initial volume, the generated condensate is collected to obtain the first stage condensate; the second stage is to continue heating distillation until the volume of the desulfurization wastewater is reduced from 90% of the initial volume to 80%, the generated condensate is collected to obtain the second stage condensate; and the third stage is obtained in the same way; and the mixture of the first stage condensate to the third stage condensate is the first stage condensate, which is used for recovering dilute ammonia water.

[0081] The second stage (i.e. the middle stage of distillation in Table 1) includes five small stages, the fourth stage is to continue heating distillation until the volume of the desulfurization wastewater is reduced from 70% of the initial volume to 60%, the generated condensate is collected to obtain the fourth stage condensate, and the fifth stage condensate, the sixth stage condensate, the seventh stage condensate and the eighth stage condensate are obtained in turn; and the mixture of the fourth stage condensate to the eighth stage condensate is the second stage condensate.

[0082] The remaining residue is liquid, which is returned to the desulfurization wastewater for recycling treatment, so as to realize the resourceful treatment of the desulfurization wastewater.

[0083] Example 5

[0084] In this embodiment, the addition concentration of the artificial zeolite is replaced by 80 g / L, and the other conditions are the same as those in Example 4.

[0085] Example 6

[0086] In this embodiment, the addition concentration of the artificial zeolite is replaced by 160 g / L, and the other conditions are the same as those in Example 4.

[0087] Comparative Example 1

[0088] In this embodiment, the addition concentration of the artificial zeolite is replaced by 0 g / L, and the other conditions are the same as those in Example 4.

[0089] Example 7

[0090] The resourceful treatment method of the first stage condensate, comprising the following steps:

[0091] S1, to the first stage condensate obtained in Example 6, the first stage condensate with a salinity of 0.22% is added artificial zeolite, the addition amount of artificial zeolite is 160 g / L, then secondary distillation is carried out at a temperature of 120°C, and the secondary condensate is collected in stages, the collection of secondary condensate includes the following 8 stages;

[0092] The first stage is to distill to reduce the volume of the first stage condensate to 90% of the initial volume, collect the generated secondary condensate to obtain the first stage secondary condensate; the second stage is to continue to distill to reduce the volume of the first stage condensate from 90% of the initial volume to 80%, collect the generated secondary condensate to obtain the second stage secondary condensate; in turn, the third stage secondary condensate, the fourth stage secondary condensate, the fifth stage secondary condensate, the sixth stage secondary condensate, the seventh stage secondary condensate and the eighth stage secondary condensate are obtained in turn;

[0093] The remaining secondary residual liquid is returned to the first stage condensate for recycling;

[0094] S2, the second and third stage condensates obtained in Example 6 are uniformly mixed to obtain a mixed condensate, the salinity of the mixed condensate is 0.08%, then secondary distillation is carried out at a temperature of 120°C, and the secondary condensate is collected in stages, the collection of secondary condensate includes the following 8 stages;

[0095] The first stage is to distill to reduce the volume of the mixed condensate to 90% of the initial volume, collect the generated secondary condensate to obtain the first stage secondary condensate; the second stage is to continue to distill to reduce the volume of the first stage condensate from 90% of the initial volume to 80%, collect the generated secondary condensate to obtain the second stage secondary condensate; in turn, the third stage secondary condensate, the fourth stage secondary condensate, the fifth stage secondary condensate, the sixth stage secondary condensate, the seventh stage secondary condensate and the eighth stage secondary condensate are obtained in turn (similar to S1);

[0096] The remaining secondary residual liquid is returned to the first stage condensate for recycling.

[0097] Example 8

[0098] In this embodiment, in addition to adjusting the salinity of the first stage condensate and the mixed condensate obtained by uniformly mixing the second and third stage condensates to 1.55% by adding sodium chloride respectively, the rest is the same as Example 7.

[0099] Example 9

[0100] A resource treatment method of the second stage condensate, comprising the following steps:

[0101] The 6th to 8th stage condensates obtained from the second stage condensate in Example 6 were mixed, and then artificial zeolite was added at an amount of 40 g / L. Air was continuously introduced at a flow rate of 1.5 L / min, and aeration treatment was performed for 14 h, so that the condensate met the standards and was used as industrial water.

[0102] Example 10

[0103] In this example, the amount of artificial zeolite added was 80 g / L, and the other conditions were the same as in Example 9.

[0104] Example 11

[0105] In this example, the amount of artificial zeolite added was 160 g / L, and the other conditions were the same as in Example 9.

[0106] Comparative Example 2

[0107] In this example, the amount of artificial zeolite added was 0 g / L, and the other conditions were the same as in Example 9.

[0108] Example 12

[0109] A resource treatment method of desulfurization wastewater, comprising the following steps:

[0110] Artificial zeolite was added to the desulfurization wastewater at a dosage of 160 g / L, and then heated distillation was performed at a temperature of 120°C, and the condensate was collected in stages. The temperature of the condensing water used for collecting the condensate was 5°C. The initial concentration of NH3-N in the desulfurization wastewater was 12454.57-12497.57 mg / L. The collection of the condensate included the following 7 stages:

[0111] The 1st stage was heating distillation until the volume of the desulfurization wastewater was reduced to 90% of the initial volume, and the generated condensate was collected to obtain the 1st stage condensate. The 2nd stage was continued heating distillation until the volume of the desulfurization wastewater was reduced from 90% to 80% of the initial volume, and the generated condensate was collected to obtain the 2nd stage condensate. Similarly, the 3rd stage condensate, the 4th stage condensate, the 5th stage condensate, the 6th stage condensate and the 7th stage condensate were obtained in turn.

[0112] The remaining residue was a liquid, which was returned to the desulfurization wastewater for recycling treatment, realizing the resource treatment of the desulfurization wastewater.

[0113] Example 13

[0114] The embodiment is identical to the embodiment 12 except that the artificial zeolite is replaced by coconut shell activated carbon.

[0115] Embodiment 14

[0116] The embodiment is identical to the embodiment 12 except that the artificial zeolite is replaced by glass beads.

[0117] Embodiment 15

[0118] A resourceful treatment method of desulfurization wastewater, comprising the following steps:

[0119] Glass beads are added to the desulfurization wastewater, the adding amount of the glass beads is 40 g / L, then heating distillation is carried out under the condition that the temperature is 120 ℃, and the condensate is collected in sections, the temperature of the condensing water used for collecting the condensate is 5 ℃, the initial concentration of NH3-N in the desulfurization wastewater is 12454.57~12497.57 mg / L, and the collection of the condensate includes the following 7 small stages.

[0120] The first stage is heating distillation until the volume of the desulfurization wastewater is reduced to 90% of the initial volume, the generated condensate is collected, and the first stage condensate is obtained; the second stage is to continue heating distillation until the volume of the desulfurization wastewater is reduced from 90% to 80% of the initial volume, the generated condensate is collected, and the second stage condensate is obtained; and the third stage condensate, the fourth stage condensate, the fifth stage condensate, the sixth stage condensate and the seventh stage condensate are obtained in turn (similar to the embodiment 1).

[0121] The remaining residue is liquid, which is returned to the desulfurization wastewater for recycling treatment, so as to realize the resourceful treatment of the desulfurization wastewater.

[0122] Embodiment 16

[0123] The embodiment is identical to the embodiment 15 except that sodium hydroxide is added after the glass beads are added to adjust the pH value of the desulfurization wastewater to 10.27.

[0124] Embodiment 17

[0125] The embodiment is identical to the embodiment 15 except that calcium hydroxide is added after the glass beads are added to adjust the pH value of the desulfurization wastewater to 10.56.

[0126] Embodiment 18

[0127] The embodiment is identical to the embodiment 15 except that sodium hydroxide and calcium hydroxide are simultaneously added after the glass beads are added to adjust the pH value of the desulfurization wastewater to 10.52.

[0128] Embodiment 19

[0129] The embodiment is the same as example 6 except that the artificial zeolite used is secondary, tertiary, quaternary, quinary and sextuple.

[0130] Detection analysis

[0131] 1) NH3-N concentration change analysis

[0132] The NH3-N concentration in the condensate is determined by the Nessler's reagent spectrophotometry (HJ535-2009) industry standard.

[0133] The NH3-N concentration determination results of the condensate obtained in the first to tenth stages in examples 1-3 and the mixed solution (i.e. the first, second and third stage condensates are mixed in example 1, and the same applies to examples 2 and 3) are shown in Table 1. Figure 1

[0134] From the analysis in (a), the NH3-N concentration of the condensate in the three groups of glass beads, coconut activated carbon and artificial zeolite shows a trend of first decreasing and then increasing with the distillation time. Among them, the artificial zeolite has the most significant promoting effect on the release of NH3-N: the initial concentration of desulfurization wastewater is 914.88-931.05 mg / L, and the NH3-N concentration of the condensate in the first to third stages of distillation is between 2234.38-1149.35 mg / L, which is much higher than that of glass beads and coconut activated carbon; the NH3-N concentration of the condensate obtained by the artificial zeolite group in the fourth to eighth stages of distillation is 940.31-279.15 mg / L. Figure 1 From the analysis in (b), the NH3-N concentration in the solution obtained by mixing all the condensates of each stage in examples 1-3 is lower than that of the original wastewater, and the release rate of NH3-N concentration in the condensate obtained by the artificial zeolite group, the coconut activated carbon group and the glass bead group decreases in turn. Figure 1 From the comprehensive analysis in (c), the artificial zeolite significantly promotes the release of NH3-N, especially in the first stage of distillation, the NH3-N concentration is 3.2 times that of the coconut activated carbon group and 9.1 times that of the glass bead group, respectively, thereby proving that the addition of artificial zeolite in the distillation process of desulfurization wastewater can effectively improve the NH3-N concentration in the first stage condensate, and provide sufficient guarantee for the subsequent circulation distillation of the first stage condensate to prepare dilute ammonia water. Figure 1 The NH3-N concentration determination results of the condensate obtained in the first to tenth stages in examples 4-6 and control example 1 and the mixed solution (the mixing method is the same as that of example 1) are shown in Table 2.

[0135] Figure 2

[0136] From the analysis in (a), the NH3-N concentration of the condensate in the three groups of glass beads, coconut activated carbon and artificial zeolite shows a trend of first decreasing and then increasing with the distillation time. Among them, the artificial zeolite has the most significant promoting effect on the release of NH3-N: the initial concentration of desulfurization wastewater is 914.88-931.05 mg / L, and the NH3-N concentration of the condensate in the first to third stages of distillation is between 2234.38-1149.35 mg / L, which is much higher than that of glass beads and coconut activated carbon; the NH3-N concentration of the condensate obtained by the artificial zeolite group in the fourth to eighth stages of distillation is 940.31-279.15 mg / L. Figure 2 ​​​Analysis in (a) shows a positive correlation between the concentration of synthetic zeolite and the concentration of NH3-N in the condensate: In the first stage of distillation, the NH3-N concentration in the 160 g / L group was 3454.29 mg / L, significantly higher than that in the 80 g / L, 40 g / L, and 0 g / L groups. With distillation, the NH3-N concentration in each group continuously decreased, with the 160 g / L group showing the largest decrease, dropping from the initial concentration to 197.96 mg / L (a decrease of 94.3%). In the eighth stage, the concentration in all groups was below 300 mg / L, a decrease of 68.5%–78.8% compared to the initial stage. Figure 2 Analysis in (b) shows a significant positive correlation between the concentration of artificial zeolite and the enrichment efficiency of NH3-N: the NH3-N concentration in the condensate of the 160 g / L group reached 1061.83 mg / L, an increase of 14.6% compared to the original solution, and significantly higher than that of the 80 g / L and 40 g / L groups. The NH3-N release rate increased with the zeolite concentration gradient, reaching 114.64% in the 160 g / L group, an increase of 5.6% and 13.9% compared to the 80 g / L and 40 g / L groups, respectively. This demonstrates that increasing the amount of artificial zeolite added can promote the release of NH3-N by enhancing ion exchange, and this effect is most significant in the first stage, providing a good foundation for the recovery of high-concentration ammonia water.

[0137] When the concentration of artificial zeolite added is 160 g / L, it has a significant effect on the release of NH3-N in the distillation treatment of desulfurization wastewater. The concentration of NH3-N in the condensate gradually decreases with the extension of distillation time (highest in the first stage). Based on this, the NH3-N concentration in the condensate obtained from the first to the eighth stages of the distillation process (S1 and S2 in Examples 7 and 8) and the solution after mixing all the condensates from each stage are measured as follows: Figure 3 As shown.

[0138] from Figure 3 Analysis in (a) shows that the NH3-N concentration during secondary distillation exhibits significant phased characteristics: Initially, the NH3-N concentration in all four condensate groups was relatively high. During the secondary distillation phase, a significant concentration gradient was generated through salinity control (increasing to 1.55%), resulting in a 4.8-fold increase in NH3-N enrichment efficiency, reaching a peak of 20063.60 mg / L. This demonstrates that increased salinity enhances NH3-N release. Figure 3(b) shows the NH3-N concentration in the condensate during the distillation process. The concentration of NH3-N decreased in a stepwise manner. The initial concentration in the first stage was 20,063.60 mg / L (salinity 0.22%), and the concentration of NH3-N increased by 24.8% when the salinity increased to 1.55%. The concentration of NH3-N in the mixed solution stage (salinity 0.08%) decreased by 68.6%, and the concentration rebounded by 10.8% when the salinity was adjusted to 1.55%. The concentration of NH3-N in the condensate in stages 2-8 decreased continuously. The concentration of NH3-N in the condensate in the group with a salinity of 0.08% decreased by 97.7% compared with the peak value, and the concentration of NH3-N in the condensate in the group with a salinity of 1.55% was 411.85 mg / L. The difference in salinity resulted in a concentration gradient difference of 37.0%. Thus, it is proved that the increase in salinity can significantly enhance the enrichment of NH3-N (10.8%-24.8%).

[0139] The results of the change of NH3-N in the mixed condensate in Example 9 to Example 11 and Control Example 2 after aeration treatment over time are shown in Figure 4 .

[0140] Figure 4 (a) is a graph of the change of NH3-N concentration over time, Figure 4 (b) is a column chart of the change of NH3-N concentration over time. From Figure 4 the analysis, it can be seen that the dosage of artificial zeolite is significantly positively correlated with the removal efficiency of NH3-N. The removal rate of the group with a dosage of 160 g / L reached 90.93% in the first 2 hours (2.4 times higher than that of the group with a dosage of 0 g / L), and the final removal rate gradient increased to 91.6%, 95.41%, and 96.1% after 14 hours with the increase of the dosage (40→80→160 g / L). Thus, it is proved that the doubling of the dosage of artificial zeolite can shorten the time to reach the standard (the treatment efficiency of the group with a dosage of 160 g / L is 4.8 times higher than that of the group with a dosage of 40 g / L), especially in the initial 2-hour reaction window period, and the decrease rate of NH3-N concentration increases by 12.3% with the increase of the dosage by 40 g / L. Thus, it is proved that increasing the dosage of artificial zeolite can enhance the rapid denitrification. In summary, the dosage of artificial zeolite has a significant impact on the removal of NH3-N in the condensate. A higher dosage can not only improve the removal rate, but also significantly shorten the time required to reach the target NH3-N concentration, thereby achieving more efficient and rapid removal of NH3-N.

[0141] The results of the determination of the NH3-N concentration in the condensate obtained in stages 1-7 and the mixed solution in Example 12-14 are shown in Figure 5 .

[0142] From Figure 5Analysis in (a) revealed that the changes in NH3-N concentration in the condensate of the three materials—glass beads, coconut shell activated carbon, and artificial zeolite—were as follows: During distillation, the initial NH3-N concentrations of the three groups were similar, but all showed a decreasing trend with increasing distillation time (stages 1-7). In stage 7, the glass bead group showed the largest decrease in NH3-N concentration, followed by the coconut shell activated carbon and artificial zeolite groups. Figure 5 Analysis in (b) showed that the NH3-N concentration in all three mixed condensates was lower than that in the original wastewater, with the glass bead group exhibiting the highest concentration, followed by the artificial zeolite and coconut shell activated carbon groups. The corresponding NH3-N release rates were 46.72%, 44.48%, and 40.64%, respectively. This demonstrates that adding glass beads significantly promotes NH3-N release in desulfurization wastewater with high ammonia nitrogen concentrations.

[0143] The results of the NH3-N concentration measurements in the condensate and the mixed solution obtained in stages 1-7 of Examples 15-18 are as follows: Figure 6 As shown.

[0144] from Figure 6 Analysis in (a) shows that the NH3-N concentration in the distillation condensate of the four groups—control group (corresponding to Example 15) (pH 6.42), NaOH (pH 0.27), Ca(OH)2 (pH 10.56), and NaOH-Ca(OH)2 mixture group (pH 10.52)—decreased with increasing distillation time. The NH3-N concentration in all four distillation condensates exhibited a two-stage characteristic of "dynamic enrichment → exponential decay." The alkaline additive significantly enhanced NH3-N volatilization: in the first stage, the NH3-N concentration in the NaOH group and the NaOH-Ca(OH)2 mixture group reached 52190.52 mg / L and 49606.76 mg / L, respectively (5.09 times higher than the neutral system), but dropped sharply in the seventh stage, corresponding to a removal rate of 98.11%. Although the initial concentration in the control group (pH 6.42) was low, the final concentration still remained at 2346.96 mg / L (removal rate 81.16%), thus demonstrating that increasing the pH (>10.2) improves the NH3-N mass transfer efficiency by 3.15 times through protonation inhibition. Figure 6 Analysis in (b) shows that the alkaline system exhibits a synergistic-antagonistic dual effect on NH3-N release: the NaOH-Ca(OH)2 mixed group achieved excessive NH3-N release (11462.93 mg / L, release rate 103.16%) at pH 10.52, which is 5.6% higher than the pure NaOH group, thus proving that calcium and sodium synergistically enhance NH3(g) mass transfer through the double-layer compression effect. In contrast, the Ca(OH)2 group alone... 2+ It reacts with NH3 to form [Ca(NH3)4] 2+ The complex, with its NH3-N concentration and release rate (37.11%) decreasing by 49.1% compared to the control group, confirms that high concentrations of Ca under alkaline conditions...2+ NH3-N volatilization will be inhibited by a dual mechanism of precipitation-complexation.

[0145] The NH3-N concentration in the condensate obtained in stages 1-8 of Example 6 and Example 19, respectively, and in the solution obtained by mixing the condensates of all stages is shown in Table 1, wherein the first use corresponds to Example 6. Figure 7

[0146] From Figure 7 Analysis in (a) shows that the NH3-N concentration decreases in two stages with distillation time and zeolite recycling times: the initial concentration of the original solution is stable at 922.5 mg / L, while the condensate concentration in the first stage decreases sharply from a maximum of 3454.29 mg / L (first use group) to 1154.46 mg / L (5 recycling times group), with a decrease of 66.6%, indicating that repeated use of zeolite significantly reduces its ion exchange capacity. With the progress of distillation to the eighth stage, the concentration of the first use group decreases to 197.96 mg / L (removal rate 94.3%), while the 5 recycling times group increases to 326.29 mg / L, with a decrease in adsorption efficiency of 35.6%, thus proving the dual mechanism of zeolite adsorption site saturation and increased NH3 mass transfer resistance. This dynamic decay confirms the threshold effect of zeolite regeneration frequency on ammonia nitrogen removal efficiency. From Figure 7 Analysis in (b) shows that the recycling of zeolite is dynamically inhibited with NH3-N release: the first distillation of the mixed solution increases the concentration to 1061.83 mg / L (release rate 114.64%), which is 14.6% higher than the initial concentration, revealing the cross-stage mass transfer inhibition effect of the initial adsorption sites of zeolite on NH3. With repeated use of zeolite, the sixth distillation concentration decreases to 592.06 mg / L (release rate 63.92%), with a decrease of 44.2%, and the release rate decay gradient from the first to the last is 50.7 percentage points, thus proving the negative feedback mechanism of zeolite regeneration times on NH3-N mass transfer efficiency.

[0147] 2) Analysis of F-concentration changes

[0148] The F - -concentration in the condensate was determined using a fluoride ion electrode.

[0149] The F - -concentration in the condensate obtained in stages 1-10 of Examples 1-3, respectively, and in the solution obtained by mixing the condensates (i.e. mixing the condensates of the first, second and third stages in Example 1, and similarly for Examples 2 and 3) is shown in Table 2. Figure 8

[0150] From Figure 8 Analysis in (a) shows that the F - ​​The concentration of F in the desulfurization wastewater first decreased and then increased with distillation time. - The initial concentration was 1272.45–1279.19 mg / L. During the initial distillation phase, the F concentration in the glass bead group and the coconut shell activated carbon group was [missing information]. - The concentration of F in the artificial zeolite group tends to stabilize. - The concentration decreased to 10.31 mg / L; during the middle stage of distillation, all three groups showed a trend of first stabilizing and then increasing; the concentration increased in the later stage of distillation. From Figure 8 Analysis in (b) shows that F in the mixed condensate obtained from the three groups - The concentrations of pollutants were all lower than those in the original wastewater. The glass bead group had the highest concentration, followed by the coconut shell activated carbon and artificial zeolite groups. The artificial zeolite group achieved a removal rate as high as 98.96%, higher than the 97.97% of the coconut shell activated carbon group and the 96.79% of the glass bead group. In summary, it can be concluded that artificial zeolite transfers F to the condensate during the distillation process. - The lowest content demonstrates that the addition of synthetic zeolite reduced F. - Transfer to condensate.

[0151] The F in the condensate and mixed solution obtained in Examples 4-6 and Control 1 in stages 1-10 (using the same mixing method as in Example 1) - Concentration measurement results are as follows Figure 9 As shown.

[0152] from Figure 9 (a) It can be seen that the addition of artificial zeolite significantly affects F. - Concentration: In the early stage of distillation, group F was 160 g / L. - The concentration decreased sharply by 41.1%, far exceeding that of the 40 g / L and 80 g / L groups, while the concentration in the 0 g / L group abnormally increased by 7.8%. During the middle stage of distillation, the F concentration in the 160 g / L group... - The concentration slightly increased, continued to decrease in the 80 g / L group, and surged abnormally by 302.9% in the 0 g / L group. This demonstrates that high-concentration zeolite (160 g / L) can rapidly retain F through ion exchange in the early stages of distillation. - The 80g / L group exhibited stable removal capacity, with a reduction of 66.9%. From Figure 9 (b) It can be seen that the addition of artificial zeolite significantly increases F - Removal efficiency: Initial F - The concentration reached 1273.69 mg / L. After distillation, the concentration in the 160 g / L group decreased to 7.74 mg / L (a decrease of 99.4%), which was 0.5%, 28.8%, and 51.0% lower than that in the 80 g / L, 40 g / L, and 0 g / L groups, respectively. - The removal rate increased significantly with increasing zeolite concentration, reaching 99.39% in the 160 g / L group, a 0.63% increase compared to the 40 g / L group. This demonstrates that the synergistic effect of zeolite adsorption and ion exchange dominates the removal of F. -removal, and high concentration zeolite (≥80 g / L) can make the condensate F - concentration is stabilized below 8 mg / L, which proves that the zeolite dosage and F - removal effect have a significant dose-effect relationship. In summary, the mixed condensate F - concentration of the condensate decreases with the increase of the zeolite dosage, and when the zeolite dosage is 40 g / L, F - concentration (10.87±0.33 mg / L) is close to the F - first emission standard 10 mg / L.

[0153] The F - concentration of the condensate obtained in the first to seventh stages of Examples 12-14 and the mixed solution is shown in Table 6. Figure 10

[0154] From Figure 10 (a), it can be seen that the F - concentration of the condensate of the three distillation systems decreases exponentially with the distillation time, and the F - concentration of the coconut activated carbon group reaches 15.44 mg / L (4.17 times higher than that of the glass bead group), but the removal rate significantly increases in the fifth to seventh stages. The initial F - concentration is concentrated in the range of 4576.45 to 4578.15 mg / L, and after seven stages of distillation, the F - concentration of the condensate of the three distillation systems decreases to 0.02-0.03 mg / L, and the total removal rate reaches 99.99% with no statistical difference between groups. Thus, it is proved that the addition of water treatment materials improves the F - removal rate. From Figure 10 (b), it can be seen that the F - concentration of the mixed condensate of the three distillation systems is reduced by 3 orders of magnitude compared with the original wastewater, and the F - removal rates of the three groups are 99.96% (glass beads), 99.86% (zeolite), and 99.76% (activated carbon), respectively. Thus, it is proved that the addition of water treatment materials can achieve a higher F - removal rate.

[0155] The F - concentration of the condensate obtained in the first to eighth stages of Examples 6 and 19 and the mixed solution of all stages of condensate is shown in Table 6. Figure 11

[0156] From Figure 11 (a), it can be seen that the fluoride migration characteristics show a threshold effect of zeolite recycling: the F -The concentration is stable at 20 mg / L or less. And Figure 11 (b) shows that the zeolite triggers a migration turning point when it is reused for the 5th time, and the mixed solution F - The concentration jumps from the stable interval of the previous four times (7.74 mg / L, removal rate 91.6%) to 12.53 mg / L (removal rate 89.3%), with an increase of 61.7%. Although the concentration decreases slightly to 12.51 mg / L in the sixth cycle, the removal rate continues to decline (89.31%), confirming that the deterioration of the zeolite structure leads to irreversible attenuation of its interception capacity for F - .

[0157] 3) Analysis of changes in salinity, TDS (Total Dissolved Solids), conductivity, and pH

[0158] The salinity in the condensate was tested using a salinity meter, the TDS in the condensate was tested using a TDS meter, the conductivity in the condensate was tested using a conductivity meter, and the pH value in the condensate was tested using a pH meter.

[0159] The results of the determination of changes in salinity, TDS, conductivity, and pH in the condensate obtained in stages 1-10 in Examples 1-3 are shown in Table 1. Figure 12

[0160] From Figure 12 (a), 12(b), and 12(c), it can be seen that the salinity, TDS, and conductivity of the condensate in the three groups of glass beads, activated carbon, and artificial zeolite all show a trend of first decreasing and then increasing. The initial values of salinity, TDS, and conductivity are 1.56%, 27.5 mg / L, and 26.65 ± 0.21 mS / cm, respectively. In the early and middle stages of distillation, the salinity of the glass bead group is relatively stable, and the TDS and conductivity decrease by 68% and 74%, respectively. The salinity of the activated carbon group decreases by 76%, and the TDS and conductivity decrease by 80%. The salinity of the artificial zeolite group decreases by 84%, and the TDS and conductivity decrease by more than 86%. In the late stage of distillation, there is a rebound: the salinity of the glass bead group increases to 0.27% (an increase of 315%), the salinity of the activated carbon group increases to 0.47% (an increase of 1075%), and the salinity of the artificial zeolite group is relatively stable, increasing to only 0.16%. In summary, the salinity concentration (0.8%) of the mixed condensate in the artificial zeolite group (40 g / L) is lower than the first-level salinity discharge standard (1%) of the "Integrated Wastewater Discharge Standard (GB 8978-1996)". From Figure 12 (d), it can be seen that the pH of the condensate in the three groups of glass beads, activated carbon, and artificial zeolite shows different changes. The initial pH of the desulfurization wastewater is 7.95, the pH of the glass bead group and the activated carbon group increases in the early and middle stages of distillation, and decreases in the late stage of distillation; the pH of the artificial zeolite group is stable at 10.39-10.43 in the early stage, and decreases from 10.36 to 9.7 in the middle and late stages of distillation. ​

[0161] The results of the salinity, TDS, conductivity, and pH changes in the condensate obtained in Examples 4 to 6, and in stages 1 to 10 of Control Example 1, are as follows: Figure 13 As shown.

[0162] from Figure 13 Analysis in (a), 13(b), and 13(c) shows that the removal of salinity, TDS, and conductivity of the condensate is enhanced with increasing concentration of synthetic zeolite: the salinity of the 160 g / L group decreased from the initial 0.26% to 0.04% (a decrease of 84.6%), a significantly greater decrease than that of the 40 g / L and 80 g / L groups. TDS in the 160 g / L group decreased from 5.05 mg / L to 1.33 mg / L (a decrease of 73.7%), an increase of 12.2% compared to the 0 g / L group. In the ≥80 g / L synthetic zeolite group, the salinity remained stable below 0.04% in stages 4-8, while the conductivity simultaneously decreased to 1.29 mS / cm (a decrease of 73.6% compared to the initial value), representing a 49.5% improvement in removal efficiency compared to the 40 g / L group. This demonstrates that synthetic zeolite removes dissolved substances through a dual mechanism of ion exchange and surface adsorption. The high-concentration group (160 g / L) achieved 78.2% salinity removal in the first three stages of distillation, proving the dose-response relationship between synthetic zeolite dosage and water quality parameter improvement, as well as the dynamic equilibrium characteristics of adsorption-release. During the mid-distillation stage, salinity, TDS, and conductivity showed differentiated stable thresholds: the 160 g / L group's salinity stabilized at 0.03% (an 88.5% decrease from the initial 0.26%), and its TDS was 0.58 mg / L, 2.1 times higher than the 0 g / L group, indicating a trace dissolution effect after adsorption saturation of high-concentration synthetic zeolite. The conductivity fluctuation range of the 80 g / L group was 67% larger than that of the 40 g / L group, while the 160 g / L group remained stable between 0.52 and 0.58 mS / cm, indicating that a stable ion exchange dynamic equilibrium can be formed when the zeolite concentration is ≥80 g / L. This demonstrates that the plateauing of water quality parameters during the mid-distillation period is essentially due to the equilibrium between zeolite adsorption site saturation and solute desorption rate. Specifically, the 160 g / L group, with its ultra-large specific surface area, exhibited a 66.7% reduction in salinity stability compared to the 0 g / L group, highlighting the long-term retention capacity of high-dose zeolite for dissolved solids. Figure 13 Analysis in (d) shows that the pH change of the condensate exhibits a significant effect of artificial zeolite concentration: the pH of the 0 g / L group increased to 10.09 (an increase of 6.1%), while the pH of the artificial zeolite-added groups decreased with increasing concentration, with the 160 g / L group dropping to 9.64 (a decrease of 3.9%), a decrease that was 2.6% and 34.5% greater than that of the 40 g / L and 80 g / L groups, respectively. The high-concentration zeolite group (≥80 g / L) maintained a stable pH below 9.7 in the later stages, 0.4 lower than the group without artificial zeolite. This demonstrates that the release of hydroxyl groups from the surface of artificial zeolite is related to Ca... 2+ / Mg 2+ Exchange leads to OH- Concentration change is the main cause of pH regulation.

[0163] The results of the determination of the changes in the salinity, TDS, conductivity and pH of the condensate obtained in stages 1 to 7 in Examples 12 to 14 are shown in Figure 14

[0164] From Figure 14 It can be seen from the analysis of (a), 14(b) and 14(c) that the salinity, TDS and conductivity of the condensate of the three distillation systems all increase linearly with the distillation time. Among them, the coconut shell activated carbon group has the weakest pore structure interception effect, and the salinity, TDS and conductivity increase by 922.7%, 908.4% and 925.5%, respectively, which is 1.55 times higher than that of the glass bead control group. After 7-stage distillation, the initial salinity, TDS and conductivity increase significantly lower than that of the activated carbon group: the salinity of the glass bead group increases to 1.45%, while the activated carbon group reaches 2.25%, and the surface cation exchange of the artificial zeolite reduces the TDS accumulation by 20.9% compared with the activated carbon group. From Figure 14 It can be seen from the analysis of (d) that the initial pH of the glass bead, coconut shell activated carbon and artificial zeolite groups is 6.42, and the pH of the condensate of the three experimental groups decreases with the increase of the distillation time.

[0165] The results of the determination of the changes in the salinity, TDS, conductivity and pH of the condensate obtained in stages 1 to 7 in Examples 15 to 18 are shown in Figure 15

[0166] From Figure 15 It can be seen from the analysis of (a), 15(b) and 15(c) that the salinity, TDS and conductivity of the condensate of the control group (glass beads), NaOH, Ca(OH)2 and NaOH-Ca(OH)2 mixed groups all increase with the increase of the distillation reaction time. Specifically, the initial salinity, TDS and conductivity of the four groups are 8.8%, 155.31 mg / L and 151.88 mS / cm, respectively, and the salinity, TDS and conductivity of the condensate of the four groups increase with the increase of the distillation reaction time in stages 1-7. Figure 15 It can be seen from the analysis of (d) that in stages 1-7 of the distillation, the pH of the condensate of the control group (glass beads) shows a decreasing trend, and the pH of the condensate of the NaOH, Ca(OH)2 and NaOH-Ca(OH)2 mixed groups shows a trend of first stabilizing and then decreasing.

[0167] 4) Analysis of the change of Tl concentration

[0168] The Tl concentration in the condensate was determined by ICP-MS method.

[0169] ​​The Tl concentration measurements in the solutions obtained after the first, second, and third stages of condensation and the complete mixing of the condensates from each stage in Examples 1-3 (i.e., the mixing of the first, second, and third stage condensates in Example 1, and the same for Examples 2 and 3) are as follows: Figure 16 As shown.

[0170] from Figure 16 Analysis in (a) shows that the Tl concentrations of the condensates from the glass beads, activated carbon, and artificial zeolite groups exhibit a "stable initially, then increasing" trend: the initial concentration range was 1628.9~1625.4 μg / L, the concentrations of each group remained stable in the early and middle stages of distillation, but all increased in the later stages. Figure 16 Analysis in (b) shows that the Tl concentration of the mixed condensate obtained in Examples 1 to 3 is lower than that of the original wastewater. Among them, the artificial zeolite group has the highest Tl concentration (9.64 μg / L), followed by the activated carbon group and the glass bead group. The removal rate of the artificial zeolite group is 99.41%. This proves that the addition of artificial zeolite can significantly reduce the Tl concentration in the condensate.

[0171] The Tl concentration measurements in Examples 4 to 6, and in the first, second, and third stages of condensation in Control Example 1, as well as in the solution after all condensates from each stage are mixed (similar to Example 1), are as follows: Figure 17 As shown.

[0172] from Figure 17 (a) and Figure 17 (b) As can be seen from the data, the Tl concentration in the 160 g / L group decreased to 1.09 μg / L during the mid-distillation process (a 99.91% decrease from the initial 1268.9 μg / L), proving that increasing the amount of artificial zeolite added can significantly reduce the Tl concentration in the condensate. In summary, the Tl concentration in the mixed condensate of all four artificial zeolite groups was below 2 μg / L, and therefore all were lower than the Class I Tl discharge standard of 5 μg / L in the "Integrated Wastewater Discharge Standard (GB 8978-1996)".

[0173] The Tl concentration measurements in the condensates from stages 1 to 7 of Examples 12 to 14, and in the solution after all condensates from each stage were mixed (similar to Example 1), are as follows: Figure 18 As shown.

[0174] from Figure 18 (a) shows that the Tl concentrations of the three groups of condensates exhibit a "decreasing then increasing" trend: the initial concentration was 2690.1~2696.4 μg / L, decreasing with increasing distillation time in stages 1 to 5, and increasing in stages 6 and 7. From Figure 18 (b) It can be seen that the Tl concentration of the mixed condensate is lower than that of the original wastewater. The Tl removal rate in the artificial zeolite group is 99.71%, the Tl removal rate in the coconut shell activated carbon group is 99.79%, and the Tl removal rate in the glass bead group is 99.57%.

[0175] The Tl concentration measurements in the condensates of stages 1 to 7 in Examples 15 to 18, and in the solution after all condensates from each stage were mixed (similar to Example 1), are as follows: Figure 19 As shown.

[0176] from Figure 19 (a) shows that the Tl concentration of the four groups of condensates exhibited a "decreasing then increasing" trend: the initial concentration was 2690.1~2696.4 μg / L, decreasing with increasing distillation time in stages 1 to 5 (Tl concentration in the control group decreased from 8.88 to 1.38 μg / L, in the NaOH group from 9.12 to 0.72 μg / L, in the Ca(OH)2 group from 0.77 to 0.16 μg / L, and in the NaOH-Ca(OH)2 mixed group from 0.28 μg / L). A sharp increase was observed in stages 6 and 7. Figure 19 (b) It can be seen that the Tl concentration of the mixed condensate was lower than that of the original wastewater, with the glass bead group having the highest concentration (11.62 μg / L), followed by the NaOH, Ca(OH)2, and NaOH-Ca(OH)2 mixed group. The removal rate showed a reverse order: the NaOH-Ca(OH)2 group reached 99.99%, which was higher than that of the Ca(OH)2, NaOH, and glass bead groups. The mixed alkaline reagents further optimized the effect through synergistic action, confirming that adjusting the pH to alkaline effectively removed thallium.

[0177] 5) COD concentration change analysis

[0178] The COD concentration in the condensate was measured.

[0179] The COD concentration measurements in Examples 4 to 6, and in the control example 1, are as follows: (i.e., the mixing of the first, second, and third stage condensates in Example 4, and similarly in Examples 5, 6, and control example 1). Figure 20 As shown.

[0180] from Figure 20 (a) It can be seen that the COD concentration decreased in a gradient with increasing artificial zeolite dosage: the 160 g / L group saw its COD drop to 11.89 mg / L in the first stage (a 68% reduction compared to the 0 g / L group), and further to 2.277 mg / L in the third stage (an 80.8% reduction), significantly better than other groups. In stages 1-3 of distillation, the COD reduction varied significantly among the groups, with the 160 g / L group showing an 80.8% reduction, while the 40 g / L group only saw a 7.9% reduction; in stages 4-8, the reduction ranged from 10% to 30%, but the 160 g / L group maintained the lowest COD level of 2.537 mg / L. This demonstrates a significant dose-response relationship between zeolite concentration and COD removal efficiency, with the optimal control window concentrated in the early and middle stages of distillation. Figure 20(b) As can be seen, the dosage of artificial zeolite is positively correlated with COD removal efficiency: the COD concentration of the condensate in the 160 g / L group is the lowest, 3.64 mg / L, which is 84.9% lower than that in the 0 g / L group, the removal rate reaches 96.89%, which is 3.3% and 21.9% higher than that in the 80 g / L group and the 40 g / L group, respectively. The error range of the 160 g / L group is narrowed by 89% compared with the 40 g / L group, indicating that high-concentration zeolite can not only enhance the stability of COD removal, but also make the COD concentration gradient of the condensate drop by 6.6 times (160 g / L vs 40 g / L). As can be seen above, the COD concentration of the mixed condensate in the artificial zeolite group decreases with the increase of the dosage of artificial zeolite, and is lower than the first-level discharge standard (60 mg / L) of the "Integrated Wastewater Discharge Standard (GB 8978-1996)".

[0181] The COD concentration determination results of the condensate in the first stage to the seventh stage in Example 12 to Example 14 and the solution after mixing all the stage condensates (the same as Example 4) are shown in Table 2. Figure 21

[0182] As can be seen from Table 2, Figure 21 (a) As can be seen, the COD concentration of the distillation condensate in the three groups increases exponentially with the distillation time, and the COD accumulation rate of the coconut shell activated carbon group significantly increases in the fifth to seventh stages. The COD concentration in the first stage is lower than 210 mg / L, and after 7-stage distillation, it increases to 8458 (glass beads), 10596 (activated carbon) and 8698 mg / L (artificial zeolite), respectively. The COD concentration of the activated carbon group after distillation is 25.3% higher than that of the glass bead group, and the artificial zeolite reduces the COD accumulation by 17.9% compared with the activated carbon due to the surface cation exchange. Figure 21 (b) As can be seen, the COD concentration of the mixed distillation condensate in the three groups is 1-2 orders of magnitude lower than that of the original wastewater, and the type of material significantly affects the interception effect of organic matter: coconut shell activated carbon group > artificial zeolite group > glass bead group, and the corresponding COD removal rates are 94.65% (glass beads) > 93.45% (artificial zeolite) > 92.49% (activated carbon). It is proved that there is a "sorption-desorption" dynamic balance in porous materials, and the coconut shell activated carbon produces a 7.8% increase in COD secondary release due to the advantages of specific surface area and micropore volume in multi-stage distillation, while the inert surface of glass beads can effectively block the resolubilization of organic matter.

[0183] The COD concentration determination results of the condensate in each stage and the solution after mixing in Example 15 to Example 18 (the same as Example 4) are shown in Table 3. Figure 22

[0184] As can be seen from Table 3, Figure 22 (a) and 22 (b), the COD removal efficiency in the alkaline system is positively correlated with the calcium ion concentration: the Ca(OH)2 group removes 93.45% of COD through Ca 2+ ​​The carboxylic acid salt co-precipitation mechanism realizes deep removal of COD (final value 196.45 mg / L, removal rate 99.61%), which is 0.76% higher than that of the NaOH group. The NaOH-Ca(OH)2 mixed group (final value 268.55 mg / L, removal rate 94.77%), while the neutral system (glass bead group) lacks alkaline hydrolysis, proves that Ca 2+ The specific adsorption of the amphiphilic organic matter effectively realizes deep removal of COD.

[0185] The COD concentration of the condensate obtained in the first stage to the eighth stage in Example 6 and Example 19 and the solution after mixing all the condensates of each stage is determined, and the results are shown in Table 1, wherein the corresponding Example 6 is used once. Figure 23

[0186] From Figure 23 As can be seen from (a) and 23 (b), the COD concentration presents a nonlinear evolution law with the zeolite cycle: the condensate concentration of each group after distillation is stably lower than 20 mg / L, and the concentration of the mixed liquid is maintained below 3.64 mg / L (removal rate >96.4%) in the first 4 cycles; but it suddenly increases to 13.91 mg / L (removal rate 88.11%) in the fifth cycle, and the concentration falls to 8.09 mg / L (removal rate 93.08%) in the sixth cycle, thereby proving that the catalytic performance degradation rate of the artificial zeolite after being reused for 5 times is only 26.8%, and verifying the critical threshold effect of the structure deterioration.

[0187] The above examples are only preferred examples for fully illustrating the present application, and the protection scope of the present application is not limited thereto. Any equivalent replacement or transformation made by the person skilled in the art on the basis of the present application is within the protection scope of the present application.​

Claims

1. A method for resourceful treatment of desulfurization wastewater, characterized in that, The method comprises the following steps: adding water treatment filler to the desulfurization wastewater, the water treatment filler being at least one selected from the group consisting of artificial zeolite, coconut shell activated carbon and glass beads; heating and distilling the desulfurization wastewater, and collecting condensed liquid in stages, the collection of the condensed liquid comprising at least three stages; in the first stage, heating and distilling until the volume of the desulfurization wastewater is reduced to 70% of the initial volume, collecting the generated condensed liquid to obtain first-stage condensed liquid, the first-stage condensed liquid being used for recovering dilute ammonia water; in the second stage, continuing to heat and distill until the volume of the desulfurization wastewater is reduced from 70% to 20% of the initial volume, collecting the generated condensed liquid to obtain second-stage condensed liquid, the second-stage condensed liquid being used for recovering dilute ammonia water or being treated as industrial water after reaching the standard; in the third stage, continuing to heat and distill until the volume of the desulfurization wastewater is reduced from 20% to 5% of the initial volume or is evaporated to dryness, collecting the generated condensed liquid to obtain third-stage condensed liquid, the third-stage condensed liquid being used for recovering dilute ammonia water or being refluxed into the original desulfurization wastewater for recycling treatment; when the remaining residue is liquid, returning to the desulfurization wastewater for recycling treatment, and when the remaining residue is solid, being converted into harmless treatment, so as to realize the resourceful treatment of the desulfurization wastewater; the method for recovering ammonia water by using the first-stage condensed liquid, comprising the following steps: adding water treatment filler to the first-stage condensed liquid, and then continuing to heat and distill at least once to obtain dilute ammonia water and first residual liquid, the first residual liquid being returned to the first-stage condensed liquid for recycling treatment; the second-stage condensed liquid is used for recovering dilute ammonia water, and the third-stage condensed liquid is used for recovering dilute ammonia water, comprising: mixing the second-stage condensed liquid and the third-stage condensed liquid, then adding artificial zeolite and increasing the salinity, and then continuing to heat and distill at least once to obtain dilute ammonia water and second residual liquid, the second residual liquid being returned to the previous stage or being treated as industrial water after reaching the standard; by adding water treatment filler, the distillation effect of the wastewater can be improved, the distillation efficiency can be improved, the impurities in the wastewater can be adsorbed, the impurity interference in the distillation process can be reduced, the purity of the condensed liquid can be improved, and the release rate of ammonia nitrogen can be improved.

2. The method for resource recovery of desulfurization wastewater according to claim 1, characterized in that, adding water treatment filler to the first-stage condensed liquid and increasing the salinity, and then continuing to heat and distill at least once to obtain dilute ammonia water and first residual liquid.

3. The method for resource recovery of desulfurization wastewater according to claim 1, characterized in that, Further comprising: adding artificial zeolite to the second-stage condensed liquid for aeration process treatment to be used as industrial water after reaching the standard.

4. The method for resource recovery of desulfurization wastewater according to claim 1, characterized in that, The water treatment filler is selected from artificial zeolite, and the addition amount of the artificial zeolite in the desulfurization wastewater is 40-160 mg / L.

5. The method for resource recovery of desulfurization wastewater according to any one of claims 1 to 4, characterized in that, The desulfurization wastewater is desulfurization wastewater generated in the desulfurization link of wet sodium alkali method for producing lithium salt by sulfation roasting method; The desulfurization wastewater has a salt concentration of 1.55-8.83%, a fluoride concentration of 1300-4600 mg / L, a heavy metal Tl concentration of 1600-2900 μg / L, a pH value of 6.42-7.98, an ammonia nitrogen (NH3-N) concentration of 900-1200 mg / L, and a COD concentration of 100-44000 mg / L.

6. The method for resource recovery of desulfurization wastewater according to claim 1, characterized in that, When the ammonia nitrogen concentration in the desulfurization wastewater is 1200-13000 mg / L, water treatment filler and alkaline reagent are added to the desulfurization wastewater, then the desulfurization wastewater is heated and distilled, and the condensate is collected in sections; The desulfurization wastewater is desulfurization wastewater generated in the desulfurization link of the wet sodium alkali method for producing lithium salt by the sulfate roasting method; The salt concentration of the desulfurization wastewater is 1.55-8.83%, the fluoride concentration is 1300-4600 mg / L, the heavy metal Tl concentration is 1600-2900 μg / L, the pH value is 6.42-7.98, and the COD concentration is 100-44000 mg / L.

7. The method for resource recovery of desulfurization wastewater according to claim 6, characterized in that, The alkaline reagent is selected from sodium hydroxide and / or calcium hydroxide; And / or, the water treatment filler is selected from glass beads.

8. The method for resource recovery of desulfurization wastewater according to claim 1, characterized in that, The heating and distillation temperature is 100-130 ℃. And / or, the heating and distillation is performed by using the waste heat of the factory.

9. The method for resource recovery of desulfurization wastewater according to claim 1, characterized in that, During the heating and distillation, the temperature of the condensate water is less than or equal to 25 ℃.

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