Resourceful treatment method of desulfurization wastewater

Abstract

The invention relates to a resourceful treatment method of desulfurization wastewater. The method comprises the following steps: adding the water treatment filler into the desulfurization wastewater; the method comprises the following steps: distilling desulfurization wastewater, collecting condensate in sections, and heating and distilling until the volume of the desulfurization wastewater is reduced to 70% of the initial volume to obtain first-stage condensate for recycling dilute ammonia water; continuously heating and distilling until the volume of the desulfurization wastewater is reduced to 20% from 70% of the initial volume to obtain a second-stage condensate; continuously heating and distilling until the volume of the desulfurization wastewater is reduced to 5% from 20% of the initial volume or is evaporated to dryness to obtain third-stage condensate, and using the second-stage condensate and the third-stage condensate for recycling dilute ammonia water or refluxing to the stock solution of the desulfurization wastewater for circular treatment or treating to reach the standard for reuse; the residual residues are subjected to innocent treatment, so that resourceful treatment of the desulfurization wastewater is The method solves the problems that the existing desulfurization wastewater treatment method is difficult to realize resource recycling, low in treatment efficiency, high in cost, easy to cause secondary pollution and difficult to discharge after reaching the standard.

Description

Technical Field

[0001] The invention relates to the technical field of resource recovery, and in particular to a resource recovery treatment method for desulfurization wastewater. Background Art

[0002] As a strategic key mineral resource in the 21st century, lithium has become the core driving force for global energy transformation and the development of emerging industries with its unique properties of "energy metal" and "green high-energy metal". Among them, the industrial processing technology of lithium mica concentrate mainly includes sulfate roasting method, sulfuric acid aging method and other systems. The limestone sintering process has significant defects such as high energy consumption and large material handling volume because it uses calcium carbonate as a roasting aid and mixes it with lithium mica. It has gradually withdrawn from the field of industrial application. In contrast, the sulfate roasting system can achieve efficient lithium extraction at a relatively low roasting temperature (about 850°C) by introducing sulfates such as potassium sulfate, sodium sulfate or calcium sulfate as an auxiliary agent. It has now become a mainstream technical solution with industrial application value.

[0003] Sulfate roasting is an important process in lithium salt production, and the environmental pollutants generated during its operation have attracted great attention. The sulfur-containing flue gas (SO2 concentration of about 0.3%) and suspended particulate matter released by this process will cause serious environmental problems if not effectively treated. Modern lithium salt companies have established a multi-level collaborative governance system for tunnel kiln flue gas generated by the roasting process. First, the energy cascade utilization is achieved through the drying kiln waste heat recovery device, and then a cyclone dust collector is combined with an absorption tower for deep purification, so that the flue gas temperature is reduced from the initial 450°C to below 120°C. The subsequent configuration of the first-stage fluoride removal system (Ca(OH)2 slurry spray) and the two-stage alkali washing device can control the SO2 emission concentration to 35mg / m 3 The following, while effectively capturing gaseous pollutants such as HF. The sulfuric acid mist waste gas generated in the desulfurization section is neutralized by an alkali spray tower (NaOH solution concentration 5-8%), and the system removal rate exceeds 95%. Among them, desulfurization wastewater is generated in the wet sodium-alkali desulfurization process. The hazards of desulfurization wastewater include: environmental level, the urea added during sulfate roasting is converted into nitrate and ammonia nitrogen, which will cause eutrophication; ecological level, heavy metals (mercury, lead, thallium) are enriched through the food chain, and fluoride destroys the soil structure, leading to salinization; health level, pollutants have carcinogenic and teratogenic risks, threatening human nerve and organ functions; industrial level, high salt corrosion accelerates equipment loss and increases operation and maintenance costs. Therefore, effective treatment of desulfurization wastewater is an urgent problem to be solved.

[0004] At present, the main treatment methods for desulfurized wastewater include chemical precipitation method, membrane treatment method, etc. However, they all have obvious technical defects. Among them, the process flow of the chemical precipitation method mainly includes four links: neutralization reaction, flocculation precipitation, gravity sedimentation and clarification separation. However, there are problems that the by-products are difficult to be recycled resourcefully and are prone to cause secondary pollution. The membrane treatment method mainly includes membrane separation method and electrodialysis method. The membrane separation technology system includes various forms such as microfiltration, ultrafiltration, nanofiltration and reverse osmosis, which can effectively intercept pollutants such as calcium and magnesium ions, colloids and heavy metals. However, there are also significant problems: the by-products are not effectively recycled resourcefully, the high-pressure operation leads to high energy consumption, the pressure difference caused by membrane fouling needs to be cleaned by chemical agents such as citric acid and sodium hypochlorite, resulting in a risk of secondary pollution, and the cost of membrane module replacement and maintenance is relatively high. The electrodialysis method realizes concentration through alternately arranged anion and cation exchange membranes and a direct current electric field, but it also fails to achieve resourceful recycling application, and the membrane fouling problem is significant during operation: the deposition of organic / inorganic pollutants leads to an increase in membrane resistance, and the treatment flow rate is reduced by about 28%. It is necessary to maintain the performance by regular chemical cleaning or membrane module replacement, and the increased operation and maintenance costs restrict its industrial promotion. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a resourceful treatment method for desulfurized wastewater, so as to solve the problem that the existing treatment methods for desulfurized wastewater are difficult to achieve resourceful recycling, and can also solve the problems of low treatment efficiency, high cost, easy secondary pollution and difficult to meet the discharge standards existing in the existing treatment methods for desulfurized wastewater.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present invention is as follows: A resourceful treatment method for desulfurized wastewater, comprising the following steps: Adding water treatment filler to the desulfurized wastewater, and the water treatment filler is selected from at least one of synthetic zeolite, coconut shell activated carbon and glass beads; Heating and distilling the desulfurized wastewater, and collecting the condensate in stages. The collection of the condensate includes at least the following three stages; The first stage: heating and distilling until the volume of the desulfurized wastewater is reduced to 70% of the initial volume, collecting the generated condensate to obtain the first-stage condensate, and the first-stage condensate is used for recycling dilute ammonia water; The second stage: continuing to heat and distill until the volume of the desulfurized wastewater is reduced from 70% of the initial volume to 20%, collecting the generated condensate to obtain the second-stage condensate, and the second-stage condensate is used for recycling dilute ammonia water or used as industrial water after being treated up to the standard; In the third stage, continue heating and distilling until the volume of the desulfurized wastewater is reduced from 20% of the initial volume to 5% or until it is completely evaporated, collect the generated condensate to obtain the condensate in the third stage, and the condensate in the third stage is used to recover dilute ammonia water or refluxed to the original solution of the desulfurized wastewater for cyclic treatment; When the remaining residue is liquid, it is returned to the desulfurized wastewater for cyclic treatment. When the remaining residue is solid, it is converted to harmless treatment to achieve the resource treatment of the desulfurized wastewater.

[0007] According to the above technical means, through the way of fractional distillation, the condensate in the first stage and the second stage can effectively recover dilute ammonia water. Dilute ammonia water is a valuable chemical product, which can be used in industrial production or other purposes, thus realizing the reuse of resources and reducing waste. The condensate in the second stage is used to recover dilute ammonia water or can be reused as industrial water after being treated up to standard. The condensate in the third stage is used to recover dilute ammonia water or refluxed to the original solution of the desulfurized wastewater for cyclic treatment. This not only reduces the demand for fresh water resources, but also reduces the water consumption cost of enterprises, and at the same time reduces the wastewater discharge. It effectively solves the problem that it is difficult to realize resource recovery and utilization in the existing treatment methods of desulfurized wastewater, and at the same time solves the problems of low treatment efficiency, high cost, easy secondary pollution and difficult up-to-standard discharge in the existing treatment methods of desulfurized wastewater.

[0008] By dividing the distillation process into three stages, it is possible to treat the wastewater according to its characteristics in different stages. For example, in the first stage, high-concentration ammonia water is mainly recovered, and in the second and third stages, low-concentration ammonia water can be recovered or reused after being treated up to standard or refluxed to the original solution of the desulfurized wastewater for cyclic treatment. This fractional treatment method improves the efficiency of resource recovery and avoids the limitations of a single treatment method. At the same time, by adding water treatment fillers such as synthetic zeolite, coconut shell activated carbon and glass beads, the distillation effect of the wastewater can be improved and the distillation efficiency can be increased. These fillers can adsorb impurities in the wastewater, reduce the interference of impurities in the distillation process, and improve the purity of the condensate. Through resource treatment, most of the wastewater is recycled, reducing the amount of wastewater discharged, thus reducing the cost of sewage treatment. The above method not only solves the problem of treating desulfurized wastewater, but also realizes the recovery and utilization of resources, which conforms to the concept of sustainable development. Through resource treatment, enterprises can achieve a balance between environmental protection and economic benefits. When the remaining residue is solid, its mass and volume are very small. Therefore, it is directly entrusted to a qualified third-party company for harmless treatment, avoiding possible secondary pollution caused by improper treatment. This treatment method meets the environmental protection requirements and reduces the pressure on the environment.

[0009] Preferably, the method for using the condensate in the first stage to recover ammonia water includes the following steps: Add water treatment filler to the first-stage condensate, and then continue with at least one heating and distillation to obtain dilute ammonia water and a first residue. The first residue is returned to the first-stage condensate to achieve cyclic treatment. By adding water treatment filler to the first-stage condensate, the release rate of ammonia nitrogen is effectively increased, thereby increasing the ammonia nitrogen content in the condensate, facilitating the preparation of high-concentration ammonia water, reducing the ammonia nitrogen in the remaining residue, and reducing the subsequent treatment difficulty.

[0010] Among them, when the ammonia nitrogen concentration in the distillate obtained after heating and distillation of the first-stage condensate does not meet the requirements of dilute ammonia water, secondary, tertiary, and more heating and distillation methods can be carried out. The ammonia nitrogen concentration in the distillate after multiple cyclic heating and distillations will gradually increase, while the contents of related salinity, heavy metals such as thallium will continue to decrease, thus meeting the requirements of dilute ammonia water.

[0011] Preferably, add water treatment filler to the first-stage condensate, increase the salinity, and then carry out at least one heating and distillation to obtain dilute ammonia water and a first residue. By adding water treatment filler to the first-stage condensate and increasing the salinity, the release rate of ammonia nitrogen is further effectively increased.

[0012] Preferably, increase the salinity of the first-stage condensate to 1.55% by adding sodium chloride.

[0013] Preferably, it further includes: adding synthetic zeolite to the second-stage condensate and carrying out aeration process treatment to meet the standard and then using it as industrial water.

[0014] Preferably, during the aeration process treatment, it is treated with air, the air flow rate is 1.5 L / min, and the time of aeration process treatment is 14 h.

[0015] Preferably, the second-stage condensate is used to recover dilute ammonia water and the third-stage condensate is used to recover dilute ammonia water, including: mixing the second-stage condensate and the third-stage condensate, then adding synthetic zeolite, increasing the salinity, and then continuing with at least one heating and distillation to obtain dilute ammonia water and a second residue. The second residue 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 meeting the treatment standard.

[0016] Preferably, increase the salinity to 1.55% by adding sodium chloride.

[0017] Preferably, using the second residue as industrial water after meeting the treatment standard means adding synthetic zeolite to the second residue and carrying out aeration process treatment to meet the standard and then using it as industrial water.

[0018] Preferably, the addition amount of synthetic zeolite in the desulfurization wastewater is 40~160 mg / L.

[0019] Preferably, the desulfurized wastewater is the desulfurized wastewater generated in the wet sodium alkali desulfurization process of producing lithium salts by the sulfate roasting method; The salt concentration of the desulfurized wastewater is 1.55 - 8.83%, the salt is mainly sodium sulfate, 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; the ammonia nitrogen (NH3-N) concentration is 900 - 1200 mg / L, and the COD concentration is 100 - 44000 mg / L.

[0020] Preferably, when the ammonia nitrogen concentration in the desulfurized wastewater is 1200 - 13000 mg / L, a water treatment filler and an alkaline reagent are added to the desulfurized wastewater, and then the desulfurized wastewater is heated and distilled, and the condensate is collected in sections; the desulfurized wastewater is the desulfurized wastewater generated in the wet sodium alkali desulfurization process of producing lithium salts by the sulfate roasting method; the salt concentration of the desulfurized 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; the COD concentration is 100 - 44000 mg / L.

[0021] Preferably, the alkaline reagent is selected from sodium hydroxide and / or calcium hydroxide; Preferably, the water treatment filler is selected from glass beads.

[0022] Preferably, the addition amount of glass beads in the desulfurized wastewater is 40 - 160 mg / L.

[0023] Preferably, a water treatment filler and an alkaline reagent are added to the first-stage condensate to make the pH value of the first-stage condensate greater than 10, and then at least one heating and distillation is continued to obtain dilute ammonia water and a first residual liquid.

[0024] Preferably, the temperature of the heating and distillation is 100 - 130 °C.

[0025] Preferably, the waste heat of the factory is used for the heating and distillation treatment process. Thus, the waste heat is recovered and utilized, effectively reducing the treatment cost.

[0026] Preferably, during the heating and distillation process, the temperature of the condensed water is less than or equal to 25 °C.

[0027] The beneficial effects of the present invention: The resource treatment method for desulfurized wastewater of the present invention. First, through the way of segmented distillation, the condensate in the first stage and the second stage can effectively recover dilute ammonia water, thus realizing the reuse of resources and reducing waste. The condensate in the second stage and the third stage can be reused as industrial water after being treated up to standard. This not only reduces the demand for fresh water resources, but also reduces the water use cost of enterprises, and at the same time reduces the wastewater discharge. By dividing the distillation process into three stages, targeted treatment can be carried out according to the wastewater characteristics of different stages. For example, the first stage mainly recovers high-concentration ammonia water, while the second stage and the third stage can recover low-concentration ammonia water or be reused after being treated up to standard or be recycled to the original solution of desulfurized wastewater for circular treatment. This segmented treatment method improves the efficiency of resource recovery and avoids the limitations of a single treatment method. At the same time, by adding water treatment fillers such as artificial zeolite, coconut shell activated carbon and glass beads, the distillation effect of wastewater can be improved and the distillation efficiency can be increased. These fillers can adsorb impurities in the wastewater, reduce the interference of impurities in the distillation process, and improve the purity of the condensate, which has the value of popularization and application in the technical field of resource recovery of wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a graph showing the change results of ammonia nitrogen concentration in the condensate of each stage of desulfurized wastewater and the solution after mixing the condensates of each stage; Figure 2 It is a graph showing the change results of ammonia nitrogen concentration in the condensate of each stage of desulfurized wastewater and the solution after mixing with the addition amount of artificial zeolite; Figure 3 It is a graph showing the change results of ammonia nitrogen concentration in the condensate of each stage of the secondary distillation of the condensate in the first stage and the solution after mixing with salinity; Figure 4 It is a graph showing the change results of ammonia nitrogen concentration with time after the condensate in the second stage is treated by aeration; Figure 5 It is a graph showing the change results of ammonia nitrogen concentration in the condensate of each stage of high ammonia nitrogen desulfurized wastewater and the solution after mixing; Figure 6 It is a graph showing the change results of ammonia nitrogen concentration in the condensate of each stage of high ammonia nitrogen desulfurized wastewater and the solution after mixing with different pH values; Figure 7 It is a graph showing the change results of ammonia nitrogen concentration in the condensate of each stage of desulfurized wastewater and the solution after mixing with the repeated use of artificial zeolite; Figure 8 It is about F in the condensate of each stage of desulfurized wastewater and the solution after mixing the condensates of each stage - Change result graph of concentration; Figure 9 It is about the addition amount of artificial zeolite to the change results of F concentration in the condensate of each stage of desulfurized wastewater and the solution after mixing - Change result graph of concentration; Figure 10 Figure of the change results of F concentration in condensate at each stage of high-ammonia-nitrogen desulfurization wastewater and the mixed solution - ; Figure 11 Figure of the change results of F concentration in condensate at each stage of desulfurization wastewater and the mixed solution with the reuse of artificial zeolite - ; Figure 12 Figure of the change results of salinity, TDS, conductivity and pH in condensate at each stage of desulfurization wastewater Figure 13 Figure of the change results of salinity, TDS, conductivity and pH in condensate at each stage with the dosage of artificial zeolite Figure 14 Figure of the change results of salinity, TDS, conductivity and pH in condensate at each stage of high-ammonia-nitrogen desulfurization wastewater Figure 15 Figure of the change results of salinity, TDS, conductivity and pH in condensate at each stage of desulfurization wastewater with different pH values Figure 16 Figure of the change results of TI concentration in condensate at each stage of desulfurization wastewater Figure 17 Figure of the change results of TI concentration in condensate at each stage with the dosage of artificial zeolite Figure 18 Figure of the change results of TI concentration in condensate at each stage of high-ammonia-nitrogen desulfurization wastewater and the mixed solution Figure 19 Figure of the change results of TI concentration in condensate at each stage of desulfurization wastewater with different pH values and the mixed solution Figure 20 Figure of the change results of COD concentration in condensate at each stage and the mixed solution with the dosage of artificial zeolite Figure 21 Figure of the change results of COD concentration in condensate at each stage of high-ammonia-nitrogen desulfurization wastewater and the mixed solution Figure 22 Figure of the change results of COD concentration in condensate at each stage of desulfurization wastewater with different pH values and the mixed solution Figure 23 Figure of the change results of COD concentration in condensate at each stage and the mixed solution with the reuse of zeolite Detailed implementation manners

[0029] The embodiments of the present invention will be described below with reference to the preferred embodiments. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for explaining the present invention, rather than limiting the protection scope of the present invention.

[0030] The desulfurized wastewater used in the following examples all comes from the wet sodium alkali desulfurization link in the process of producing lithium salts by the sulfate roasting method of lepidolite concentrate. Among them, the water quality characteristics of the desulfurized wastewater include: ① high salt content and complex ion composition, high salt concentration (1.55 - 8.83%), mainly sodium sulfate (formed by the reaction of desulfurizer NaOH and SO2), and at the same time containing high-concentration fluoride (1300 - 4600 mg / L, originating from NaF and Na2SiF6 generated by fluorine elements in the ore); ② the concentration of heavy metal Tl reaches 1600 - 2900 μg / L; ③ acidity and alkalinity, the pH of the desulfurized wastewater fluctuates between 6.42 and 7.98, and fluoride (such as HF) further exacerbates acid corrosion, threatening the equipment life; ④ the concentration of NH3-N is 900 - 13000 mg / L, and the concentration of COD is 100 - 44000 mg / L.

[0031] Example 1 A resource treatment method for desulfurized wastewater, comprising the following steps: Add synthetic zeolite to the desulfurized wastewater, the dosage of the synthetic zeolite is 40 g / L, then carry out heating distillation at a temperature of 120 °C, and collect the condensate in stages. The temperature of the condensed water used for collecting the condensate is 5 °C. The initial concentration of NH3-N in the desulfurized wastewater is 914.88 - 931.05 mg / L. The collection of the condensate includes the following three major stages; The first stage (i.e., the early stage of distillation in Table 1) includes 3 small stages. The first stage is to heat and distill until the volume of the desulfurized wastewater is reduced to 90% of the initial volume, and collect the generated condensate to obtain the condensate of the first stage; the second stage is to continue heating and distilling until the volume of the desulfurized wastewater is reduced from 90% of the initial volume to 80%, and collect the generated condensate to obtain the condensate of the second stage; the third stage is to continue heating and distilling until the volume of the desulfurized wastewater is reduced from 80% of the initial volume to 70%, and collect the generated condensate to obtain the condensate of the third stage; the mixture of the condensate from the first stage to the third stage is the condensate of the first stage, and the condensate of the first stage is used to recover dilute ammonia water; The second stage (i.e., the middle stage of distillation in Table 1) includes 5 small stages. In the 4th stage, continue heating and distilling until the volume of the desulfurized wastewater decreases from 70% of the initial volume to 60%, collect the generated condensate to obtain the 4th-stage condensate; in the 5th stage, continue heating and distilling until the volume of the desulfurized wastewater decreases from 60% of the initial volume to 50%, collect the generated condensate to obtain the 5th-stage condensate; and so on to obtain the 6th-stage condensate, 7th-stage condensate, and 8th-stage condensate; the mixture of the 4th-stage condensate to the 8th-stage condensate is the second-stage condensate; The third stage (i.e., the later stage of distillation in Table 1) includes 2 small stages. In the 9th stage, continue heating and distilling until the volume of the desulfurized wastewater decreases from 20% of the initial volume to 10%, collect the generated condensate to obtain the 9th-stage condensate; in the 10th stage, continue heating and distilling until the volume of the desulfurized wastewater decreases from 10% of the initial volume to 5%, collect the generated condensate to obtain the 10th-stage condensate; the mixture of the 9th-stage condensate and the 10th-stage condensate is the third-stage condensate; The remaining residue is liquid, which is returned to the desulfurized wastewater for recycling treatment to achieve the resource treatment of the desulfurized wastewater.

[0032] Table 1 Definition of distillation stages Example 2 In this example, except that the synthetic zeolite is replaced by coconut shell activated carbon, the rest is the same as in Example 1.

[0033] Example 3 In this example, except that the synthetic zeolite is replaced by glass beads, the rest is the same as in Example 1.

[0034] Example 4 A resource treatment method for desulfurized wastewater includes the following steps: Add synthetic zeolite to the desulfurized wastewater, with the dosage of the synthetic zeolite being 40 g / L, then carry out heating and distillation at a temperature of 120 °C, and collect the condensate in stages. The temperature of the condensed water used for collecting the condensate is 5 °C. The initial concentration of NH3-N in the desulfurized wastewater is 914.885 - 931.05 mg / L. The collection of the condensate includes the following three major stages; The first stage (i.e., the early stage of distillation in Table 1) includes 3 small stages. In the first stage, the desulfurized wastewater is heated and distilled until its volume is reduced to 90% of the initial volume, and the generated condensate is collected to obtain the condensate of the first stage. In the second stage, the heating and distillation continue until the volume of the desulfurized wastewater is reduced from 90% of the initial volume to 80%, and the generated condensate is collected to obtain the condensate of the second stage. And so on, the condensate of the third stage is obtained. The mixture of the condensate from the first stage to the third stage is the condensate of the first stage, and the condensate of the first stage is used to recover dilute ammonia water. The second stage (i.e., the middle stage of distillation in Table 1) includes 5 small stages. In the fourth stage, the heating and distillation continue until the volume of the desulfurized wastewater is reduced from 70% of the initial volume to 60%, and the generated condensate is collected to obtain the condensate of the fourth stage. And so on, the condensate of the fifth stage, the condensate of the sixth stage, the condensate of the seventh stage, and the condensate of the eighth stage are obtained in turn. The mixture of the condensate from the fourth stage to the eighth stage is the condensate of the second stage. The remaining residue is liquid, which is returned to the desulfurized wastewater for cyclic treatment to achieve the resource treatment of the desulfurized wastewater.

[0035] Example 5 In this example, except that the addition concentration of artificial zeolite is replaced with 80 g / L, the other conditions are the same as those in Example 4.

[0036] Example 6 In this example, except that the addition concentration of artificial zeolite is replaced with 160 g / L, the other conditions are the same as those in Example 4.

[0037] Control Example 1 In this example, except that the addition concentration of artificial zeolite is replaced with 0 g / L, the other conditions are the same as those in Example 4.

[0038] Example 7 A method for resource treatment of the condensate of the first stage, comprising the following steps: S1. Add artificial zeolite to the condensate of the first stage with a salinity of 0.22% obtained in Example 6, the addition amount of the artificial zeolite is 160 g / L, and then perform secondary distillation at a temperature of 120 °C, and collect the secondary condensate in segments. The collection of the secondary condensate includes the following 8 stages; In the first stage, distill until the volume of the condensate in the first stage decreases to 90% of the initial volume. Collect the generated secondary condensate to obtain the secondary condensate of the first stage. In the second stage, continue distilling until the volume of the condensate in the first stage decreases from 90% of the initial volume to 80%. Collect the generated secondary condensate to obtain the secondary condensate of the second stage. And so on, successively obtain the secondary condensate of the third stage, the secondary condensate of the fourth stage, the secondary condensate of the fifth stage, the secondary condensate of the sixth stage, the secondary condensate of the seventh stage, and the secondary condensate of the eighth stage. The remaining secondary residue liquid is returned to the condensate in the first stage to achieve cyclic treatment. S2. Uniformly mix the condensate of the second and third stages in the condensate of the first stage obtained in Example 6 to obtain a mixed condensate with a salinity of 0.08%. Then, perform secondary distillation at a temperature of 120 °C and collect the secondary condensate in stages. The collection of the secondary condensate includes the following 8 stages. In the first stage, distill until the volume of the mixed condensate decreases to 90% of the initial volume. Collect the generated secondary condensate to obtain the secondary condensate of the first stage. In the second stage, continue distilling until the volume of the condensate in the first stage decreases from 90% of the initial volume to 80%. Collect the generated secondary condensate to obtain the secondary condensate of the second stage. And so on (similar to that in S1), successively obtain the secondary condensate of the third stage, the secondary condensate of the fourth stage, the secondary condensate of the fifth stage, the secondary condensate of the sixth stage, the secondary condensate of the seventh stage, and the secondary condensate of the eighth stage. The remaining secondary residue liquid is returned to the condensate in the first stage to achieve cyclic treatment.

[0039] Example 8 In this example, except that the salinity of the condensate in the first stage and the mixed condensate obtained by uniformly mixing the condensate of the second and third stages is adjusted to 1.55% by adding sodium chloride, the rest is the same as in Example 7.

[0040] Example 9 The resource treatment method for the condensate in the second stage includes the following steps: Mix the condensate of the 6th - 8th stages in the condensate of the second stage obtained in Example 6, then add synthetic zeolite with an addition amount of 40 g / L, continuously introduce air with a flow rate of 1.5 L / min, and perform aeration treatment for 14 h so that the condensate meets the standards and can be used as industrial water.

[0041] Example 10 In this example, except that the addition amount of synthetic zeolite is 80 g / L, the rest of the conditions are the same as those in Example 9.

[0042] Example 11 In this example, except that the addition amount of synthetic zeolite is 160 g / L, the other conditions are the same as those in Example 9.

[0043] Control Example 2 In this example, except that the addition amount of synthetic zeolite is 0 g / L, the other conditions are the same as those in Example 9.

[0044] Example 12 A resource treatment method for desulfurized wastewater, comprising the following steps: Add synthetic zeolite to the desulfurized wastewater, with the dosage of the synthetic zeolite being 160 g / L. Then, carry out heating distillation at a temperature of 120 °C, and collect the condensate in stages. The temperature of the condensed water used for collecting the condensate is 5 °C. The initial concentration of NH3-N in the desulfurized wastewater is 12454.57 - 12497.57 mg / L. The collection of the condensate includes the following 7 small stages; The first stage is to heat and distill until the volume of the desulfurized wastewater is reduced to 90% of the initial volume, and collect the generated condensate to obtain the first-stage condensate; the second stage is to continue heating and distilling until the volume of the desulfurized wastewater is reduced from 90% of the initial volume to 80%, and collect the generated condensate to obtain the second-stage condensate; and so on (similar to Example 1), successively obtaining the third-stage condensate, the fourth-stage condensate, the fifth-stage condensate, the sixth-stage condensate, and the seventh-stage condensate; The remaining residue is liquid, which is returned to the desulfurized wastewater for cyclic treatment to achieve the resource treatment of the desulfurized wastewater.

[0045] Example 13 In this example, except that the synthetic zeolite is replaced by coconut shell activated carbon, the other parts are the same as those in Example 12.

[0046] Example 14 In this example, except that the synthetic zeolite is replaced by glass beads, the other parts are the same as those in Example 12.

[0047] Example 15 A resource treatment method for desulfurized wastewater, comprising the following steps: Add glass beads to the desulfurized wastewater, with the dosage of the glass beads being 40 g / L. Then, carry out heating distillation at a temperature of 120 °C, and collect the condensate in stages. The temperature of the condensed water used for collecting the condensate is 5 °C. The initial concentration of NH3-N in the desulfurized wastewater is 12454.57 - 12497.57 mg / L. The collection of the condensate includes the following 7 small stages; In the first stage, the desulfurized wastewater is heated and distilled until its volume is reduced to 90% of the initial volume, and the generated condensate is collected to obtain the condensate of the first stage; in the second stage, heating and distillation continue until the volume of the desulfurized wastewater is reduced from 90% of the initial volume to 80%, and the generated condensate is collected to obtain the condensate of the second stage; and so on (similar to Example 1), successively obtaining the condensate of the third stage, the condensate of the fourth stage, the condensate of the fifth stage, the condensate of the sixth stage, and the condensate of the seventh stage; The remaining residue is a liquid, which is returned to the desulfurized wastewater for recycling treatment to achieve the resource treatment of the desulfurized wastewater.

[0048] Example 16 In this example, except that after adding glass beads, sodium hydroxide is also added to adjust the pH value of the desulfurized wastewater to 10.27, the rest is the same as Example 15.

[0049] Example 17 In this example, except that after adding glass beads, calcium hydroxide is also added to adjust the pH value of the desulfurized wastewater to 10.56, the rest is the same as Example 15.

[0050] Example 18 In this example, except that after adding glass beads, sodium hydroxide and calcium hydroxide are simultaneously added to adjust the pH value of the desulfurized wastewater to 10.52, the rest is the same as Example 15.

[0051] Example 19 In this example, except that the used artificial zeolite is reused for the second, third, fourth, fifth, and sixth times, the rest is the same as Example 6.

[0052] Detection and analysis 1) Analysis of the change in NH3-N concentration The NH3-N concentration in the condensate is measured using the industry standard of "Nessler's reagent spectrophotometry (HJ535 - 2009)".

[0053] The measurement results of the NH3-N concentration in the condensate obtained in the 1st to 10th stages of Examples 1 to 3 respectively and the mixed solution (that is, the first, second, and third stage condensates in Example 1 are mixed, and the same applies to Examples 2 and 3) are as Figure 1 shown.

[0054] From Figure 1As can be seen from the analysis in (a), the concentration of NH₃-N in the condensate shows a trend of first decreasing and then increasing with the distillation time in the three groups of glass beads, coconut shell activated carbon, and synthetic zeolite. Among them, the synthetic zeolite has the most significant promoting effect on the release of NH₃-N: the initial concentration of the desulfurized wastewater is 914.88 - 931.05 mg / L, and the concentration of NH₃-N in the condensate in the 1st - 3rd stage of distillation is between 2234.38 - 1149.35 mg / L, which is much higher than that of the glass beads and coconut shell activated carbon; the concentration of NH₃-N in the condensate obtained in the synthetic zeolite group in the 4th - 8th stage of distillation is 940.31 - 279.15 mg / L. From Figure 1 As can be seen from the analysis in (b), the concentration of NH₃-N in the solution after mixing all the condensates in each stage of Examples 1 to 3 is lower than that of the original wastewater. Among them, the release rates of the concentration of NH₃-N in the condensates obtained in the synthetic zeolite group, coconut shell activated carbon group, and glass bead group decrease in turn. From Figure 1 From the comprehensive analysis, it can be seen that the synthetic zeolite significantly promotes the release of NH₃-N. Especially in the 1st stage of distillation, the concentration of NH₃-N is 3.2 times that of the coconut shell activated carbon group and 9.1 times that of the glass bead group, thus proving that adding synthetic zeolite in the process of distilling desulfurized wastewater can effectively increase the concentration of NH₃-N in the condensate in the first stage, providing sufficient guarantee for the subsequent cyclic distillation of the condensate in the first stage to prepare dilute ammonia water.

[0055] The measurement results of the concentration of NH₃-N in the condensates obtained in the 1st - 10th stages of Examples 4 - 6 and Comparative Example 1, as well as the mixed solution (in the same mixing method as in Example 1 above), are as Figure 2 shown.

[0056] From Figure 2 As can be seen from the analysis in (a), there is a positive correlation between the dosage concentration of synthetic zeolite and the concentration of NH₃-N in the condensate: in the 1st stage of distillation, the concentration of NH₃-N in the 160 g / L group is 3454.29 mg / L, which is significantly higher than that in the 80 g / L, 40 g / L, and 0 g / L groups. With the distillation, the concentration of NH₃-N in each group continues to decrease, and the 160 g / L group has the largest decrease, from the initial to 197.96 mg / L (the decrease rate reaches 94.3%). The concentration in all groups is lower than 300 mg / L in the 8th stage, and it decreases by 68.5 - 78.8% compared with the initial stage. From Figure 2As analyzed in (b), the addition concentration of synthetic zeolite has a significant positive correlation with the NH3-N enrichment efficiency: the NH3-N concentration in the condensate of the 160 g / L group reaches 1061.83 mg / L, which is 14.6% higher than that of the original solution and significantly higher than those of the 80 g / L group and the 40 g / L group. The NH3-N release rate increases with the increasing gradient of zeolite concentration. The release rate of the 160 g / L group reaches 114.64%, which is 5.6% and 13.9% higher than those of the 80 g / L group and the 40 g / L group respectively. This proves that increasing the dosage of synthetic zeolite can promote the release of NH3-N by strengthening the ion exchange effect, and this effect is the most significant in the first stage, providing a good basis for the recovery of high-concentration ammonia water.

[0057] When the addition concentration of synthetic zeolite is 160 g / L, it has a significant effect on the release of NH3-N in the distillation treatment of desulfurized wastewater. The NH3-N concentration in the condensate gradually decreases with the prolonging of the distillation time (the highest in the first stage). Based on this, ammonia water is recovered by secondary distillation of the condensate in the early stage of distillation. The measurement results of the NH3-N concentration in the condensate obtained from the first stage to the eighth stage and the solution after mixing all the condensate at each stage in S1 and S2 of Example 7 and Example 8 are as Figure 3 shown.

[0058] As Figure 3 analyzed in (a), the NH3-N concentration in the secondary distillation shows significant stages: the NH3-N concentrations of the four groups of condensate are relatively high in the initial stage. A significant concentration gradient is generated by salinity regulation (increased to 1.55%) in the secondary distillation stage, and the NH3-N enrichment efficiency is increased by 4.8 times, with a peak value of 20063.60 mg / L, thus proving that increasing the salinity can strengthen the release of NH3-N. As Figure 3 analyzed in (b), the NH3-N concentration shows a stepwise decay during the distillation process: the initial concentration in the first stage reaches 20063.60 mg / L (salinity 0.22%). After the salinity rises to 1.55%, the NH3-N concentration increases by 24.8%; in the mixed liquid stage (salinity 0.08%), the NH3-N concentration drops sharply by 68.6%, and when the salinity is readjusted to 1.55%, the concentration rebounds by 10.8%. The NH3-N concentration in the condensate from the second to the eighth stage continues to decay. The final concentration of the 0.08% salinity group decreases by 97.7% compared with the peak value, and the remaining concentration of the 1.55% salinity group is 411.85 mg / L. The salinity difference leads to a concentration gradient difference of 37.0%. This proves that increasing the salinity can significantly strengthen the NH3-N enrichment (the increase range is 10.8% - 24.8%).

[0059] The change results of NH3-N with time after aeration treatment of the mixed condensate in Example 9 to Example 11 and Control Example 2 are as Figure 4 shown.

[0060] Figure 4Figure (a) is a graph showing the change of NH3-N concentration over time, Figure 4 Figure (b) is a bar chart showing the change of NH3-N concentration over time. From Figure 4 the analysis, it can be seen that there is a significant positive correlation between the dosage of synthetic zeolite and the NH3-N removal efficiency: the removal rate of the 160 g / L group reached 90.93% in the first 2 hours (2.4 times higher than that of the 0 g / L group), and with the increase of the dosage (40 → 80 → 160 g / L), the final removal rate gradient increased to 91.6%, 95.41% and 96.1% after 14 hours. Thus, it is proved that doubling the dosage of synthetic zeolite can synchronously shorten the time to reach the standard (the treatment efficiency of the 160 g / L group is 4.8 times higher than that of the 40 g / L group). Especially in the initial 2-hour reaction window period, for every 40 g / L increase in the dosage, the deceleration rate of NH3-N concentration increased by 12.3%, thus proving the strengthening effect of increasing the dosage of synthetic zeolite on rapid denitrification. In summary, the dosage of synthetic zeolite has a significant impact on the removal effect of NH3-N in 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, thus achieving more efficient and rapid NH3-N removal.

[0061] The measured results of the NH3-N concentration in the condensate obtained in the 1st - 7th stages of Examples 12 - 14 and the mixed solution are as Figure 5 shown.

[0062] From Figure 5 the analysis of (a), the change of NH3-N concentration in the condensate of the three groups of materials, namely glass beads, coconut shell activated carbon and synthetic zeolite, is as follows: during the distillation process, the initial NH3-N concentrations of the three groups are similar, and all show a downward trend with the extension of the distillation time (1st - 7th stages). In the 7th stage, the NH3-N concentration of the glass bead group decreased the most, followed by the coconut shell activated carbon and synthetic zeolite groups. From Figure 5 the analysis of (b), the NH3-N concentration of the mixed condensate of the three groups is lower than that of the original wastewater. Among them, the glass bead group remains the highest, followed by the synthetic zeolite and coconut shell activated carbon groups. The corresponding NH3-N release rates are 46.72%, 44.48% and 40.64% respectively. Thus, it is proved that adding glass beads has a significant promoting effect on NH3-N release for the desulfurization wastewater with high ammonia nitrogen concentration.

[0063] The measured results of the NH3-N concentration in the condensate obtained in the 1st - 7th stages of Examples 15 - 18 and the mixed solution are as Figure 6 shown.

[0064] From Figure 6Analysis in (a) shows that the NH₃-N concentrations in the distillation condensates of the four groups, namely the control group (corresponding to Example 15) (pH 6.42), NaOH (pH 0.27), Ca(OH)₂ (pH 10.56), and the NaOH-Ca(OH)₂ mixture group (pH 10.52), decrease with the increase of distillation time. The NH₃-N concentrations in the distillation condensates of all four groups exhibit a two-stage characteristic of "dynamic enrichment → exponential decay". The alkaline additives significantly enhance the volatilization of NH₃-N: the NH₃-N concentrations in the first stage of the NaOH group and the NaOH-Ca(OH)₂ mixture group reach 52190.52 mg / L and 49606.76 mg / L respectively (5.09 times higher than that in the neutral system), but drop sharply in the seventh stage, corresponding to a removal rate of 98.11%. Although the initial concentration of the control group (pH 6.42) is relatively low, the final value still remains 2346.96 mg / L (removal rate 81.16%), thus proving that increasing the pH (>10.2) can improve the mass transfer efficiency of NH₃-N by 3.15 times through protonation inhibition. From Figure 6 Analysis in (b) shows that the alkaline system has a dual effect of synergy - antagonism on the release of NH₃-N: the NaOH-Ca(OH)₂ mixture group realizes the excessive release of NH₃-N (11462.93 mg / L, release rate 103.16%) under the condition of pH 10.52, which is 5.6% higher than that of the pure NaOH group, thus proving that the calcium-sodium synergy enhances the mass transfer of NH₃(g) through the double-layer compression effect. For the single Ca(OH)₂ group, due to Ca 2+ forming a complex [Ca(NH₃)₄] with NH₃ 2+ , its NH₃-N concentration and release rate (37.11%) decrease by 49.1% compared with the control group, confirming that high-concentration Ca 2+ will inhibit the volatilization of NH₃-N through the dual mechanisms of precipitation - complexation under alkaline conditions.

[0065] The measurement results of the NH₃-N concentrations in the condensate obtained in each of the 1st - 8th stages and the solution after mixing all the condensate in each stage in Example 6 and Example 19 are as Figure 7 shown, where the first utilization corresponds to Example 6.

[0066] From Figure 7From the analysis in (a), it can be seen that the NH3-N concentration shows a dual decay with the distillation time and the number of cycles of artificial zeolite: the concentration of the raw solution is stable at 922.5 mg / L in the initial stage, while the concentration of the condensate in the first stage drops sharply from the highest 3454.29 mg / L (one-time utilization group) to 1154.46 mg / L (five-times-recycling group), a decrease of 66.6%, indicating that the repeated use of artificial zeolite significantly weakens its ion exchange capacity. As the distillation progresses to the eighth stage, the concentration of the one-time utilization group drops to 197.96 mg / L (removal rate 94.3%), while the five-times-recycling group rises to 326.29 mg / L, and the adsorption efficiency decreases by 35.6%, thus proving the dual action mechanism of saturation of artificial zeolite adsorption sites 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 From the analysis in (b), it can be seen that the recycling of zeolite and the release of NH3-N show a dynamic inhibition relationship: the concentration of the mixed liquid abnormally rose to 1061.83 mg / L (release rate 114.64%) during the first distillation, an increase of 14.6% over the initial concentration, revealing the cross-stage mass transfer inhibition effect of the initial adsorption site of zeolite on NH3. With the repeated use of zeolite, the concentration of the sixth distillation dropped to 592.06 mg / L (release rate 63.92%), a decrease of 44.2%, and the release rate attenuation gradient from the first to the last time reached 50.7 percentage points, thus proving the negative feedback mechanism of the number of zeolite regenerations on the mass transfer efficiency of NH3-N.

[0067] 2) Analysis of F-concentration changes Determination of F in Condensate Using Fluoride Ion Electrode - concentration.

[0068] The F in the condensates obtained in the 1st to 10th stages in Examples 1 to 3 and the mixed solutions (i.e., the mixture of the condensates in the first, second and third stages in Example 1, and the same for Examples 2 and 3) - The concentration determination results are as follows Figure 8 shown.

[0069] from Figure 8 From the analysis in (a), it can be seen that the condensate F of the three groups of glass beads, coconut shell activated carbon and artificial zeolite - The concentration first decreases and then increases with the distillation time. - The initial concentration of F in the glass bead group and coconut shell activated carbon group was 1272.45~1279.19 mg / L. - The concentration of F in the artificial zeolite group - The concentration of 1% chlorine dropped to 10.31 mg / L; in the middle of distillation, the three groups showed a trend of first stabilizing and then increasing; in the later stage of distillation, the concentration increased. Figure 8 (b) shows that the F -The concentrations are all lower than those of the original wastewater. The glass bead group has the highest concentration, followed by the coconut shell activated carbon and synthetic zeolite groups. The removal rate of the synthetic zeolite group is as high as 98.96%, higher than that of the coconut shell activated carbon group (97.97%) and the glass bead group (96.79%). In summary, the F - content transferred to the condensate by the synthetic zeolite during the distillation process is the least, thus proving that the addition of synthetic zeolite reduces the transfer of F - to the condensate.

[0070] The F - concentrations in the condensate and the mixed solution (in the same mixing method as in Example 1 above) obtained in Stages 1 to 10 of Examples 4 to 6 and Control 1 respectively are shown as follows. Figure 9 shown.

[0071] From Figure 9 Figure (a), it can be seen that the addition of synthetic zeolite significantly affects the F - concentration: In the early stage of distillation, the F - concentration in the 160 g / L group decreased sharply by 41.1%, far exceeding those of the 40 g / L and 80 g / L groups, and the concentration in the 0 g / L group increased abnormally by 7.8%. In the middle stage of distillation, the F - concentration in the 160 g / L group increased slightly, the 80 g / L group continued to decrease, and the 0 g / L group increased abnormally by 302.9%. It is proved that high-concentration zeolite (160 g / L) can rapidly intercept F - through ion exchange in the early stage of distillation; the 80 g / L group shows a stable removal ability, with a reduction of 66.9%. From Figure 9 Figure (b), it can be seen that the addition of synthetic zeolite significantly improves the F - removal efficiency: The initial F - concentration reached 1273.69 mg / L. After distillation, the concentration in the 160 g / L group decreased to 7.74 mg / L (a reduction of 99.4%), which was 0.5%, 28.8%, and 51.0% lower than those of the 80 g / L, 40 g / L, and 0 g / L groups respectively. The F - removal rate increased significantly with the increase of zeolite concentration. The 160 g / L group reached 99.39%, which was 0.63% higher than that of the 40 g / L group. It is proved that the synergistic effect of zeolite adsorption and ion exchange dominates the F - removal, and high-concentration zeolite (≥80 g / L) can keep the F - concentration in the condensate below 8 mg / L, proving the significant dose-effect relationship between the zeolite dosage and the F - removal effect. In summary, the F - concentration in the mixed condensate of the synthetic zeolite group decreases with the increase of the synthetic zeolite dosage. When the addition concentration of synthetic zeolite is 40 g / L, the F - concentration (10.87 ± 0.33 mg / L) is close to the F of the Integrated Wastewater Discharge Standard (GB 8978-1996).- The first-class discharge standard is 10 mg / L.

[0072] The F concentrations in the condensate and the mixed solution obtained in the 1st to 7th stages of Examples 12 to 14 respectively - The concentration measurement results are as Figure 10 shown.

[0073] From Figure 10 the analysis in (a), it can be seen that the F concentrations in the condensate of the three distillation systems - all show exponential decay with the distillation time. Due to the adsorption and interception effect, the F concentration in the coconut shell activated carbon group reaches 15.44 mg / L in the 1st stage (4.17 times higher than that of the glass bead group), but the removal rate significantly increases in the 5th - 7th stages. The initial F concentration is concentrated in the range of 4576.45 to 4578.15 mg / L. After 7 - stage distillation, the F concentrations in the three distillation systems all drop to 0.02 - 0.03 mg / L, and the total removal rate reaches 99.99% with no significant statistical difference among the groups. This proves that the addition of water treatment materials improves the F - removal rate. From - the analysis in (b), it can be seen that the F concentrations in the mixed condensate of the three groups are all reduced by three orders of magnitude compared with the original wastewater, and the removal rates of F are 99.96% (glass beads), 99.86% (synthetic zeolite), and 99.76% (activated carbon) respectively. This proves that the addition of water treatment materials can all achieve a relatively high removal rate of F. - From Figure 10 the analysis in (b), it can be seen that the F concentration in the mixed condensate of the three groups of distillates is reduced by three orders of magnitude compared with the original wastewater, and the removal rates of F are 99.96% (glass beads), 99.86% (synthetic zeolite), and 99.76% (activated carbon) respectively. This proves that the addition of water treatment materials can all achieve a relatively high removal rate of F. - all decrease by three orders of magnitude compared with the original wastewater, and the removal rates of F are 99.96% (glass beads), 99.86% (synthetic zeolite), and 99.76% (activated carbon) respectively. This proves that the addition of water treatment materials can all achieve a relatively high removal rate of F. - removal rate. From - the analysis in (b), it can be seen that the F concentrations in the mixed condensate of the three groups are all reduced by three orders of magnitude compared with the original wastewater, and the removal rates of F are 99.96% (glass beads), 99.86% (synthetic zeolite), and 99.76% (activated carbon) respectively. This proves that the addition of water treatment materials can all achieve a relatively high removal rate of F.

[0074] The F concentrations in the condensate obtained in the 1st to 8th stages of Examples 6 and 19 respectively, and in the solution after mixing all the condensate of each stage - The concentration measurement results are as Figure 11 shown, where the first - time utilization corresponds to Example 6.

[0075] From Figure 11 the analysis in (a), it can be seen that the fluoride migration characteristics show a threshold effect of zeolite recycling: during the distillation process, the F concentrations in the condensate of each group are all stable below 20 mg / L. While - in Figure 11 the analysis in (b), it shows that when the zeolite is reused for the 5th time, a migration turning point is triggered, and the F concentration in the mixed solution suddenly increases from the stable range 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 slightly drops 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 an irreversible decay in its interception ability for F. - concentration suddenly increases from the stable range 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 slightly drops 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 an irreversible decay in its interception ability for F. - interception ability.

[0076] 3) Analysis of changes in salinity, TDS (Total Dissolved Solids), conductivity, and pH A salinometer was used to measure the salinity in the condensate, a TDS meter was used to measure the TDS in the condensate, a conductivity meter was used to measure the conductivity in the condensate, and a pH meter was used to measure the pH value in the condensate.

[0077] The measurement results of the changes in salinity, TDS, conductivity, and pH in the condensate obtained in the 1st to 10th stages of Examples 1 to 3 are as Figure 12 shown.

[0078] From Figure 12 (a), 12(b), and 12(c), it can be analyzed that the salinity, TDS, and conductivity of the condensate in the three groups of glass beads, activated carbon, and synthetic zeolite all show a trend of first decreasing and then increasing. The three-dimensional 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 both decrease by 80%; the salinity of the synthetic zeolite group decreases by 84%, and the TDS and conductivity decrease by more than 86%. There is a rebound in the later stage of distillation: the salinity of the glass bead group rises to 0.27% (an increase of 315%), the salinity of the activated carbon group rises to 0.47% (an increase of 1075%), and the synthetic zeolite group is relatively stable, only rising to 0.16%. In summary, the salinity concentration (0.8%) of the mixed condensate in the synthetic zeolite group (40 g / L) is lower than the first-class discharge standard of salinity in the Comprehensive Wastewater Discharge Standard (GB 8978-1996), which is 1%. From Figure 12 (d), it can be analyzed that the pH of the condensate in the three groups of glass beads, activated carbon, and synthetic zeolite shows different changes. The initial pH of the desulfurized wastewater is 7.95. In the early and middle stages of distillation, the pH of the glass bead group and the activated carbon group rises, and it drops in the later stage of distillation; the pH of the synthetic zeolite group is stable at 10.39 - 10.43 in the early stage, and drops from 10.36 to 9.7 in the middle and later stages of distillation.

[0079] The measurement results of the changes in salinity, TDS, conductivity, and pH in the condensate obtained in the 1st to 10th stages of Examples 4 to 6, and Comparative Example 1 are as Figure 13 shown.

[0080] From Figure 13It can be analyzed from (a), 13 (b) and 13 (c) that the salinity, TDS and conductivity of the condensate show enhanced removal with the increase of the 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%), and the decrease was significantly higher than that of the 40 g / L and 80 g / L groups. The TDS showed that the 160 g / L group decreased from 5.05 mg / L to 1.33 mg / L (a decrease of 73.7%), which was 12.2% higher than that of the 0 g / L group. The salinity of the synthetic zeolite group with ≥80 g / L was stable below 0.04% in the 4-8 stages, and the conductivity decreased synchronously to 1.29 mS / cm (a decrease of 73.6% compared with the initial value), and the removal efficiency was 49.5% higher than that of the 40 g / L group. Thus, it is proved that synthetic zeolite removes dissolved substances through the dual mechanisms of ion exchange and surface adsorption, and the high-concentration group (160 g / L) completed 78.2% of the salinity removal in the first 3 stages before distillation, proving the dose-effect relationship between the dosage of synthetic zeolite and the improvement of water quality parameters and the adsorption-release dynamic equilibrium characteristics. In the middle stage of distillation, the salinity, TDS and conductivity of each group showed different stable thresholds: the salinity of the 160 g / L group was stable at 0.03% (a decrease of 88.5% compared with the initial 0.26%), and the TDS was 0.58 mg / L, which was 2.1 times higher than that of the 0 g / L group, proving that there was a trace dissolution effect after the high-concentration synthetic zeolite was saturated in adsorption. The fluctuation range of the conductivity of the 80 g / L group was 67% larger than that of the 40 g / L group, while the 160 g / L group was stable between 0.52-0.58 mS / cm, indicating that a stable ion exchange dynamic equilibrium could be formed when the zeolite concentration was ≥80 g / L. Thus, it is proved that the essence of the water quality parameters tending to the plateau stage in the middle stage of distillation is that the zeolite adsorption sites are saturated and the solute desorption rate reaches equilibrium. Among them, the stable salinity value of the 160 g / L group was 66.7% lower than that of the 0 g / L group due to the ultra-large specific surface area, highlighting the long-term interception ability of high-dose zeolite for dissolved solid phase substances. From Figure 13 It can be analyzed from (d) that the change of the pH value of the condensate shows a significant synthetic zeolite concentration effect: the pH value of the 0 g / L group increased to 10.09 (an increase of 6.1%), while the pH value of the synthetic zeolite addition group showed a gradient decrease with the increase of the concentration. The pH value of the 160 g / L group decreased to 9.64 (a decrease of 3.9%), and the decrease was 2.6% and 34.5% higher than that of the 40 g / L and 80 g / L groups respectively. The pH value of the high-concentration zeolite group (≥80 g / L) was stable below 9.7 in the later stage, which was 0.4 lower than that of the group without synthetic zeolite. Thus, it is proved that the release of surface hydroxyl groups of synthetic zeolite and Ca 2+ / Mg 2+ exchange led to the change of OH - concentration as the main reason for pH regulation.

[0081] The measurement results of the changes in salinity, TDS, conductivity and pH in the condensate obtained in the 1st to 7th stages of Examples 12 to 14 are as Figure 14 shown.

[0082] From Figure 14 Analysis of (a), 14 (b) and 14 (c) shows that the salinity, TDS and conductivity of the condensate in the three distillation systems all increase linearly with the distillation time. Among them, due to the weakest interception effect of the porous structure in the coconut shell activated carbon group, the increases in its salinity, TDS and conductivity reach 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 of the initial salinity, TDS and conductivity, the parameter increases in the glass bead group and the zeolite group are significantly lower than those in the activated carbon group: when the salinity in the glass bead group rises to 1.45%, it has reached 2.25% in the activated carbon group, and the cation exchange effect on the surface of the synthetic zeolite reduces the TDS accumulation by 20.9% compared with the activated carbon group. From Figure 14 Analysis of (d) shows that the initial pH of the three distillation experiments of glass beads, coconut shell activated carbon and synthetic zeolite is 6.42, and the pH of the condensate in the three experimental groups decreases with the increase of the distillation time.

[0083] The measurement results of the changes in salinity, TDS, conductivity and pH in the condensate obtained in the 1st to 7th stages of Examples 15 to 18 are as Figure 15 shown.

[0084] From Figure 15 Analysis of (a), 15 (b) and 15 (c) shows that the salinity, TDS and conductivity of the condensate in the control group (glass beads), NaOH, Ca(OH)2 and NaOH-Ca(OH)2 mixed groups 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. In the 1st - 7th stages of distillation, the salinity, TDS and conductivity of the condensate in the four groups increase with the increase of the distillation reaction time. From Figure 15 Analysis of (d) shows that in the 1st - 7th stages of distillation, the pH value of the condensate in the control group (glass beads) shows a decreasing trend, and the pH values of the condensate in the three groups of NaOH, Ca(OH)2 and NaOH-Ca(OH)2 mixed groups first tend to be stable and then decrease.

[0085] 4) Analysis of Tl concentration change The Tl concentration in the condensate was measured by ICP-MS method.

[0086] The measurement results of the Tl concentration in the condensate in the first, second and third stages of Examples 1 to 3 and the solution after mixing all the condensate in each stage (that is, the condensate in the first, second and third stages of Example 1 is mixed, and the same applies to Examples 2 and 3) are as Figure 16 shown.

[0087] From Figure 16It can be analyzed from (a) that the Tl concentrations in the condensate of the glass bead, activated carbon, and synthetic zeolite groups show a trend of "stable first and then rising": the initial concentration ranges from 1628.9 to 1625.4 μg / L. The concentrations of each group remain stable in the middle stage of distillation, while they all increase in the later stage of distillation. From Figure 16 It can be analyzed from (b) that the Tl concentrations in the mixed condensate obtained in Examples 1 to 3 are all lower than those in the original wastewater. Among them, the synthetic zeolite group is the highest (9.64 μg / L), followed by the activated carbon group and the glass bead group. The removal rate of the synthetic zeolite group is 99.41%. Thus, it is proved that the addition of synthetic zeolite can significantly reduce the TI in the condensate.

[0088] The measurement results of the Tl concentrations in the first, second, and third stage condensates and the solution after mixing all the stage condensates (similarly to Example 1) in Examples 4 to 6 and Comparative Example 1 are as Figure 17 shown.

[0089] From Figure 17 (a) and Figure 17 (b), it can be seen that the Tl concentration in the middle stage of distillation in the 160 g / L group drops to 1.09 μg / L (a 99.91% decrease compared to the initial 1268.9 μg / L), which proves that the increase in the addition amount of synthetic zeolite can significantly reduce the Tl concentration in the condensate. In summary, the Tl concentrations in the mixed condensates of the four synthetic zeolite groups are all below 2 μg / L, so they are all lower than the first-class discharge standard of Tl of 5 μg / L in the Integrated Wastewater Discharge Standard (GB 8978-1996).

[0090] The measurement results of the Tl concentrations in the condensate from the first stage to the seventh stage and the solution after mixing all the stage condensates (similarly to Example 1) in Examples 12 to 14 are as Figure 18 shown.

[0091] From Figure 18 (a), it can be seen that the Tl concentrations in the three groups of condensates show a trend of "decreasing first and then rising": the initial concentration is 2690.1 to 2696.4 μg / L, and it decreases with the increase of distillation time from the first stage to the fifth stage, and all increase in the sixth stage to the seventh stage. From Figure 18 (b), it can be seen that the Tl concentrations in the mixed condensates are all lower than those in the original wastewater. Among them, the removal rate of Tl in the synthetic zeolite group is (99.71%), the removal rate of Tl in the coconut shell activated carbon group is 99.79%, and the removal rate of Tl in the glass bead group is 99.57%.

[0092] The measurement results of the Tl concentrations in the condensate from the first stage to the seventh stage and the solution after mixing all the stage condensates (similarly to Example 1) in Examples 15 to 18 are as Figure 19 shown.

[0093] FromFigure 19 As can be seen from (a), the Tl concentrations in the four groups of condensate show a trend of "decreasing first and then increasing": the initial concentration is 2690.1 - 2696.4 μg / L, and it decreases with the increase of distillation time from the 1st to the 5th stage (the Tl concentration in the control group decreases from 8.88 to 1.38 μg / L, the Tl concentration in the NaOH group decreases from 9.12 to 0.72 μg / L, the Tl concentration in the Ca(OH)2 group decreases from 0.77 to 0.16 μg / L, and the Tl concentration in the NaOH-Ca(OH)2 mixed group decreases from 0.28 μg / L), and there is a sharp increase in both the 6th and 7th stages. From Figure 19 As can be seen from (b), the Tl concentrations in the mixed condensate are all lower than those in the original wastewater. Among them, the glass bead group has the highest concentration (11.62 μg / L), followed by the NaOH, Ca(OH)2, and NaOH-Ca(OH)2 mixed groups. The removal rates show an inverse order: the NaOH-Ca(OH)2 group reaches (99.99%), which is higher than the Ca(OH)2, NaOH, and glass bead groups. The mixed alkaline reagents further optimize the effect through synergistic effects, confirming that adjusting the pH to alkaline is effective in removing thallium.

[0094] 5) Analysis of COD concentration changes The COD concentrations in the condensate were measured.

[0095] The measurement results of the COD concentrations in the condensate at each stage and the mixed solutions in Examples 4 to 6, as well as Control Example 1 (i.e., the first, second, and third stage condensates in Example 4 were mixed, and the same applies to Examples 5, 6, and Control Example 1) are as Figure 20 shown.

[0096] From Figure 20 As can be seen from (a), the COD concentration shows a gradient decrease with the increase of the dosage of synthetic zeolite: the COD in the 160 g / L group decreased to 11.89 mg / L at the 1st stage (a 68% decrease compared to the 0 g / L group), and further decreased to 2.277 mg / L at the 3rd stage (a decrease of 80.8%), which is significantly better than other groups. During the 1st - 3rd stages of distillation, the COD reduction rates of each group are significantly different. Among them, the reduction rate of the 160 g / L group is 80.8%, while the 40 g / L group only decreases by 7.9%; during the 4th - 8th stages, the reduction rates of each group are 10 - 30%, but the 160 g / L group still maintains the lowest COD level of 2.537 mg / L. It proves that there is a significant dose effect between the zeolite concentration and the COD removal efficiency, and the optimal control window is concentrated in the middle and early stages of distillation. From Figure 20As can be seen from (b), the dosage of synthetic zeolite has a significant positive correlation with the COD removal efficiency: the COD concentration of the condensate in the 160 g / L group is the lowest at 3.64 mg / L, which is 84.9% lower than that in the 0 g / L group, and the removal rate reaches 96.89%, which is 3.3% and 21.9% higher than those in the 80 g / L group and 40 g / L group respectively. The error range in the 160 g / L group is 89% narrower than that in the 40 g / L group, indicating that high-concentration zeolite can not only enhance the stability of COD removal, but also reduce the COD concentration gradient of the condensate by 6.6 times (160 g / L vs 40 g / L). In summary, the COD concentration of the mixed condensate in the synthetic zeolite group decreases with the increase of the dosage of synthetic zeolite, and all are lower than the first-class discharge standard of COD in the Comprehensive Wastewater Discharge Standard (GB8978-1996) (60 mg / L).

[0097] The measurement results of the COD concentration in the condensate from the 1st stage to the 7th stage and the solution after mixing all the condensate at each stage in Examples 12 to 14 (the same as in Example 4) are as Figure 21 shown.

[0098] From Figure 21 As can be seen from (a), the COD concentration of the three groups of distilled condensate increases exponentially with the distillation time, and the COD accumulation rate in the coconut shell activated carbon group increases significantly in the 5th - 7th stage. The COD concentration in the 1st stage is all lower than 210 mg / L, and after 7-stage distillation, it rises to 8458 (glass beads), 10596 (activated carbon), and 8698 mg / L (synthetic zeolite) respectively. The COD concentration in the latter stage of distillation in the activated carbon group is 25.3% higher than that in the glass bead group, while the COD accumulation in the synthetic zeolite group is 17.9% lower than that in the activated carbon group due to the surface cation exchange effect. From Figure 21 As can be seen from (b), the COD concentration after mixing the three groups of distilled condensate decreases by 1 - 2 orders of magnitude compared with the original wastewater, and the material type significantly affects the organic matter interception effect: coconut shell activated carbon group > synthetic zeolite group > glass bead group, and the corresponding COD removal rates are 94.65% (glass beads) > 93.45% (synthetic zeolite) > 92.49% (activated carbon). It proves that there is a "adsorption-desorption" dynamic equilibrium in the porous materials. Due to the advantages of specific surface area and micropore volume, the coconut shell activated carbon has a 7.8% COD secondary release increment in multi-stage distillation, while the inert surface of the glass beads can effectively block the re-dissolution of organic matter.

[0099] The measurement results of the COD concentration in the condensate at each stage and the solution after mixing in Examples 15 to 18 (the same as in Example 4) are as Figure 22 shown.

[0100] From Figure 22 As can be seen from (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 passes through Ca 2+- The COD was deeply removed by the carboxylate coprecipitation mechanism (the final value was 196.45 mg / L, and the removal rate was 99.61%), which was 0.76% higher than that of the NaOH group. The NaOH-Ca(OH)2 mixed group (the final value was 268.55 mg / L, and the removal rate was 94.77%). The neutral system (glass bead group) lacked alkaline hydrolysis, which proved that Ca 2+ The specific adsorption of amphiphilic organic compounds effectively achieved the deep removal of COD.

[0101] The measurement results of the COD concentration in the condensate obtained in the 1st to 8th stages of Example 6 and Example 19 respectively, and the solution after all the condensate in each stage was mixed are as Figure 23 shown, where the first utilization corresponded to Example 6.

[0102] From Figure 23 (a) and 23(b), it can be seen that the COD concentration shows a non-linear evolution law with the recycling of synthetic zeolite: the concentration of the condensate in each group was stably lower than 20 mg / L during distillation, while the concentration of the mixed solution remained below 3.64 mg / L in the first 4 cycles of the zeolite (removal rate > 96.4%); however, it suddenly increased to 13.91 mg / L in the 5th cycle (removal rate 88.11%), and the concentration dropped to 8.09 mg / L in the 6th cycle (removal rate 93.08%). This proved that the catalytic performance decay rate of the synthetic zeolite was only 26.8% after being reused 5 times, verifying the critical threshold effect of its structural deterioration.

[0103] The above embodiments are only preferred embodiments given to fully illustrate the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention.

Claims

1. A resource treatment method for desulfurized wastewater, characterized in that, It includes the following steps: Add water treatment filler to the desulfurized wastewater, and the water treatment filler is selected from at least one of synthetic zeolite, coconut shell activated carbon and glass beads; Heat and distill the desulfurized wastewater, and collect the condensate in stages. The collection of the condensate includes at least the following three stages; In the first stage, heat and distill until the volume of the desulfurized wastewater is reduced to 70% of the initial volume, collect the generated condensate to obtain the first-stage condensate, and the first-stage condensate is used to recover dilute ammonia water; In the second stage, continue to heat and distill until the volume of the desulfurized wastewater is reduced from 70% of the initial volume to 20%, collect the generated condensate to obtain the second-stage condensate, and the second-stage condensate is used to recover dilute ammonia water or as industrial water after reaching the standard; In the third stage, continue to heat and distill until the volume of the desulfurized wastewater is reduced from 20% of the initial volume to 5% or until it is evaporated to dryness, collect the generated condensate to obtain the third-stage condensate, and the third-stage condensate is used to recover dilute ammonia water or return to the original desulfurized wastewater for cyclic treatment; When the remaining residue is liquid, it is returned to the desulfurized wastewater for cyclic treatment. When the remaining residue is solid, it is converted into harmless treatment to realize the resource treatment of the desulfurized wastewater.

2. The resource treatment method of the desulfurized waste water according to claim 1, characterized in that The method for using the first-stage condensate to recover ammonia water includes the following steps: Add water treatment filler to the first-stage condensate, and then continue to carry out at least one heating and distillation to obtain dilute ammonia water and the first residual liquid. The first residual liquid returns to the first-stage condensate to realize cyclic treatment.

3. The resource treatment method of the desulfurized waste water according to claim 2, characterized in that Add water treatment filler to the first-stage condensate, and increase the salinity, and then continue to carry out at least one heating and distillation to obtain dilute ammonia water and the first residual liquid.

4. The resource treatment method for desulfurized wastewater according to claim 1, characterized in that, It also includes: Add synthetic zeolite to the second-stage condensate for aeration process treatment and use it as industrial water after reaching the standard; Alternatively, the second-stage condensate is used to recover dilute ammonia water and the third-stage condensate is used to recover dilute ammonia water, including: Mix the second-stage condensate and the third-stage condensate, then add synthetic zeolite, and increase the salinity, and then continue to carry out at least one heating and distillation to obtain dilute ammonia water and the second residual liquid. The second residual liquid returns to the previous stage or is used as industrial water after reaching the standard.

5. The resource treatment method for desulfurized wastewater according to claim 1, characterized in that, The water treatment filler is selected from synthetic zeolite, and the addition amount of synthetic zeolite in the desulfurized wastewater is 40~160mg / L.

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

7. The resource treatment method of the desulfurized waste water according to claim 1, characterized in that, When the ammonia nitrogen concentration in the desulfurized wastewater is 1200~13000mg / L, add water treatment filler and alkaline reagent to the desulfurized wastewater, then heat and distill the desulfurized wastewater, and collect the condensate in stages; The desulfurized wastewater is the desulfurized wastewater generated in the wet sodium alkali method desulfurization link of the production of lithium salts by the sulfate roasting method; The salt concentration of the desulfurized 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; the COD concentration is 100 - 44000 mg / L.

8. The resource treatment method for desulfurized wastewater according to claim 7, 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.

9. The resource treatment method of the desulfurized wastewater according to claim 1, wherein The temperature of the heating and distillation is 100 - 130 °C; And / or, the heating and distillation is carried out using the waste heat of the factory.

10. The resource treatment method for desulfurized wastewater according to claim 1, characterized in that, During the heating and distillation process, the temperature of the condensed water is less than or equal to 25 °C.

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