Method and system for resourceful treatment of high-concentration organic salt-containing waste liquid

Abstract

The application relates to the technical field of chemical waste liquid, in particular to a high-concentration organic salt-containing waste liquid resource treatment method and system. In the method, high-concentration organic salt-containing waste liquid is first introduced into a high-flux direct pyrolysis system for rapid pyrolysis, part of the pyrolysis gas is discharged after tail gas treatment; and the carbon salt mixture is subjected to salt water impurity removal and refined salt separation to obtain product salt. The application can not only safely and efficiently remove the organic matter in the high-concentration organic salt-containing waste liquid, but also realize the resourceization and productization of the salt.

Description

Technical Field

[0001] This invention relates to the field of chemical waste liquid technology, specifically to a method and system for the resource-based treatment of high-concentration organic saline waste liquid. Background Technology

[0002] In the process of chemical production, a large amount of high-concentration organic salt waste liquid is generated. This waste liquid is characterized by high biological toxicity, high concentration of organic matter, and high salt content, which poses a great threat to human health and the ecological environment and is difficult to treat.

[0003] For the treatment of high-concentration organic saline waste liquid, the commonly used methods are: (1) using multi-effect evaporation and MVR process to reduce the volume of saline waste liquid, but the mother liquor and waste salt remaining in the evaporation process are hazardous waste and still need to be treated; (2) using wet catalytic oxidation process to harmlessly treat saline waste liquid, but the catalyst is expensive, the investment cost is large, it is easy to cause secondary pollution, and the safety is poor; (3) using a combination of physical and chemical and biological methods to harmlessly treat saline waste liquid, but a large amount of sludge will be generated in the physical and chemical treatment process. Such wastewater treatment sludge is defined as hazardous waste and still needs to be treated; the high salt content has a great impact on the biological treatment, making the system operation unstable.

[0004] In response to the aforementioned technological problems, there is an urgent need to find a safe and effective treatment method for high-concentration organic saline wastewater that can efficiently remove organic matter from the wastewater while separating and purifying the salts, thereby achieving the harmlessness, resource utilization, and productization of high-concentration organic saline wastewater.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The primary objective of this invention is to provide a method for the resource-based treatment of high-concentration organic saline wastewater.

[0007] The second objective of this invention is to provide a resource recovery system for high-concentration organic saline waste liquid.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] A method for resource recovery treatment of high-concentration organic saline waste liquid includes the following steps:

[0010] (a) Under anaerobic conditions, high-concentration organic salt waste liquid is contacted with high-temperature flue gas to undergo a cracking reaction, yielding a carbon-salt mixture and cracked gas;

[0011] (b) The pyrolysis gas in (a) is reacted with pure oxygen to produce high-temperature flue gas. Part of the high-temperature flue gas is returned to (a) to react with the high-concentration organic salt waste liquid to produce a pyrolysis reaction.

[0012] (c) Treat the remaining high-temperature flue gas from (b) as exhaust gas;

[0013] (d) Dissolve the carbon-salt mixture in (a) in water, and then sequentially process it through carbon particle removal, addition of NaOH and Ca(OH)2, calcium removal and membrane filtration to obtain a purified salt solution.

[0014] (e) The salt solution obtained in (d) is recovered according to the salt components and purified to obtain a single salt product.

[0015] Furthermore, in (a), the reaction time of the pyrolysis reaction is 2-3 s, and the temperature of the pyrolysis reaction is 1100-1300 °C;

[0016] Furthermore, in (a), the carbon-salt mixture and the pyrolysis gas after the pyrolysis reaction are cooled to 500-600°C through heat exchange.

[0017] Furthermore, the heat exchanged in (a) can serve as the heat source for the oxidation reaction in (b).

[0018] Furthermore, in (b), the temperature of the pure oxygen oxidation reaction is 1200℃-1300℃, and the reaction time is 2-3s.

[0019] Furthermore, in (c), the exhaust gas treatment includes: the high-temperature flue gas is successively subjected to pure oxygen oxidation, denitrification, rapid cooling alkaline washing and dust removal before being discharged; the denitrification is preferably SNCR (selective non-catalytic reduction) denitrification.

[0020] Furthermore, in (c), the temperature of pure oxygen oxidation for exhaust gas treatment is 1100-1200℃, the oxygen content of dry flue gas is >6%, and the time of pure oxygen oxidation is 2-3s.

[0021] Furthermore, the temperature of the carbonate mixture in (d) is 40-60℃;

[0022] Preferably, Mg in the brine is removed by adding NaOH and Ca(OH)2. 2+ Fe 2+ Fe 3+ Cu 2+ At least one of them;

[0023] Preferably, Ca is further removed by adding Na2CO3. 2+ ;

[0024] Preferably, the salt solution is obtained by microfiltration to remove impurities, and then the separation and recovery in (e) are performed.

[0025] A resource recovery system for high-concentration organic saline waste liquid includes a high-throughput direct pyrolysis system, a brine removal system, and a refining and separating system. The solid discharge outlet of the high-throughput direct pyrolysis system is connected to the inlet of the brine removal system, and the outlet of the brine removal system is connected to the inlet of the refining and separating system.

[0026] Furthermore, the high-throughput direct pyrolysis system includes a feeding unit, an anaerobic pyrolysis unit, an oxidation unit, a tail gas treatment unit, and a discharge unit; the brine purification system includes a dissolution unit and a filtration unit; wherein,

[0027] The outlet of the feeding unit is connected to the inlet of the anaerobic pyrolysis unit, which sends the high-concentration organic salt waste liquid to the anaerobic pyrolysis unit.

[0028] The gas outlet of the anaerobic pyrolysis unit is connected to the gas inlet of the oxidation unit, and the gas generated in the anaerobic pyrolysis unit is sent to the oxidation unit.

[0029] The gas outlet of the oxidation unit is connected to the inlet of the anaerobic pyrolysis unit and the inlet of the tail gas treatment unit, respectively. Part of the gas generated in the oxidation unit enters the anaerobic pyrolysis unit and part enters the tail gas treatment unit.

[0030] The solid discharge port of the anaerobic pyrolysis unit is connected to the inlet of the discharge unit, and the solid material generated in the anaerobic pyrolysis unit is sent to the discharge unit.

[0031] The outlet of the discharge unit is connected to the inlet of the dissolution unit of the brine removal system, so that the solid material is sent to the dissolution unit of the brine removal system.

[0032] The outlet of the dissolving unit is connected to the inlet of the filtration unit, and the salt solution generated in the dissolving unit is sent to the filtration unit.

[0033] The outlet of the filtration unit is connected to the refining and separating salt system, which will send the salt solution produced by the filtration unit to the refining and separating salt system.

[0034] Compared with the prior art, the technical effects of the present invention are as follows:

[0035] This invention can not only safely and efficiently remove organic matter from high-concentration organic saline waste liquid, but also realize the resource utilization and productization of salts.

[0036] In the oxidation unit, the present invention can utilize the cracked gas generated in the anaerobic pyrolysis unit. In the oxidation unit, the cracked gas itself can be used as fuel to undergo an oxidation reaction with pure oxygen, which can reduce the external fuel demand and thus reduce the system operating cost. Attached Figure Description

[0037] The various technical features of the present invention and their relationships will be further explained below with reference to the accompanying drawings. The drawings are exemplary; some technical features are not shown to scale, and some drawings may omit technical features commonly used in the art to which this invention pertains that are not essential for understanding and implementing the invention, or may additionally show technical features that are not essential for understanding and implementing the invention. In other words, the combination of various technical features shown in the drawings is not intended to limit the invention. Furthermore, throughout this invention, the same reference numerals refer to the same things. Specific descriptions of the drawings are as follows:

[0038] Figure 1 This is a schematic diagram of the resource utilization treatment of high-concentration organic saline waste liquid;

[0039] Figure 2 This is a process flow diagram of a high-concentration organic salt waste liquid resource utilization treatment system. Detailed Implementation

[0040] The specific embodiments of the present invention will now be described in detail.

[0041] "High-concentration organic saline waste liquid" can be evaporation mother liquor, concentrated mother liquor, organic waste liquid, etc. generated in the chemical production process. This type of waste liquid has the characteristics of high organic matter concentration, high salt content, and great difficulty in treatment.

[0042] The high-concentration organic saline wastewater resource utilization system provided by this invention includes a high-throughput direct pyrolysis system, a brine impurity removal system, and a refining and salt separation system. For example... Figure 1 As shown, the solid discharge outlet of the high-throughput direct pyrolysis system is connected to the inlet of the brine removal system, and the outlet of the brine removal system is connected to the inlet of the refining and separating system.

[0043] Specifically, such as Figure 2 As shown, the high-throughput direct pyrolysis system includes a feeding unit, an anaerobic pyrolysis unit, an oxidation unit, a tail gas treatment unit, and a discharge unit; the brine purification system includes a dissolution unit and a filtration unit. Among these,

[0044] The outlet of the feeding unit is connected to the inlet of the anaerobic pyrolysis unit, and the high-concentration organic salt waste liquid is sent to the anaerobic pyrolysis unit through the feeding unit.

[0045] The gas outlet of the anaerobic pyrolysis unit is connected to the gas inlet of the oxidation unit, and the gas (cracking gas) generated in the anaerobic pyrolysis unit is sent to the oxidation unit.

[0046] The gas outlet of the oxidation unit is connected to the inlet of the anaerobic pyrolysis unit and the inlet of the tail gas treatment unit, respectively. Part of the gas generated in the oxidation unit enters the anaerobic pyrolysis unit to participate in the cracking reaction, and the other part enters the tail gas treatment unit for treatment and is then discharged in compliance with standards.

[0047] The solid discharge port of the anaerobic pyrolysis unit is connected to the inlet of the discharge unit, and the solid material generated in the anaerobic pyrolysis unit is sent to the discharge unit.

[0048] The outlet of the discharge unit is connected to the inlet of the dissolution unit of the brine purification system, so that the solid material is sent to the dissolution unit of the brine purification system.

[0049] The outlet of the dissolving unit is connected to the inlet of the filtration unit, and the salt solution generated in the dissolving unit is sent to the filtration unit to obtain a purified salt solution.

[0050] The outlet of the filtration unit is connected to the refining and salt separation system, which will send the salt solution produced by the filtration unit to the refining and salt separation system for separation and purification to obtain salt products.

[0051] The following is a detailed explanation of each unit:

[0052] Feeding unit

[0053] The high-concentration organic saline waste liquid is fed into the anaerobic pyrolysis unit via the feeding unit. Specifically, the high-concentration organic saline waste liquid is pumped into the anaerobic pyrolysis unit.

[0054] Anaerobic pyrolysis unit

[0055] Under anaerobic conditions, the high-concentration organic saline wastewater rapidly undergoes a pyrolysis reaction with the high-temperature flue gas (generated by the oxidation reaction of pyrolysis gas and pure oxygen) produced by the oxidation unit. The reaction time is 2-3 seconds, and the reaction temperature is 1100-1300℃, preferably around 1200℃, producing a mixture of carbon and salt, as well as pyrolysis gas. After the pyrolysis reaction, to avoid melting and caking, the temperature of the carbon-salt mixture and pyrolysis gas is reduced to 500-600℃ through efficient heat exchange when they reach the discharge port. Simultaneously, the heat from the heat exchange serves as a heat source for the oxidation unit. The resulting carbon-salt mixture is then settled and introduced into the discharge unit, while the generated pyrolysis gas enters the oxidation unit.

[0056] Oxidation unit

[0057] The pyrolysis gas produced in the anaerobic pyrolysis unit is introduced into the oxidation unit, where it undergoes an oxidation reaction with pure oxygen. Specifically, the pyrolysis gas is filtered before entering the pure oxygen thermal oxidizer. The pure oxygen thermal oxidizer operates at temperatures exceeding 1200℃, preferably 1200℃-1300℃, with a reaction time of 2-3 seconds. The pyrolysis gas itself serves as a fuel source, undergoing high-temperature oxidation within the oxidation unit, resulting in the complete oxidation and decomposition of organic matter. A portion of the generated high-temperature flue gas is introduced into the anaerobic pyrolysis unit to continue the pyrolysis reaction with the feed material, forming a loop. This internal circulation of pyrolysis gas minimizes external fuel requirements and reduces operating costs. The remaining portion of the high-temperature flue gas enters the tail gas treatment unit.

[0058] Exhaust gas treatment unit

[0059] Excess high-temperature flue gas generated in the oxidation unit is introduced into the tail gas treatment unit for processing. The tail gas treatment unit consists of a secondary oxidation chamber, a denitrification system (e.g., SNCR), a quench alkaline scrubbing tank, wet dust removal, activated carbon adsorption, an induced draft fan, and a chimney. Excess high-temperature flue gas enters the secondary oxidation chamber, where the temperature is controlled at 1100℃-1200℃, the dry flue gas oxygen content is >6%, and the pyrolysis steam is oxidized in the secondary oxidation chamber for at least 2 seconds, preferably 2-3 seconds, with an average removal rate of 99.99%. After a series of treatments including denitrification, quenching, and dust removal, the tail gas meets emission standards, and the emission concentration and rate of polluting gases are lower than the limits specified in the "Standard for Pollution Control of High-Temperature Oxidation of Hazardous Waste" (GB18484-2020).

[0060] Discharge unit

[0061] The outlet of the discharge unit is connected to the inlet of the dissolution unit of the brine purification system, so that the solid material is sent to the dissolution unit of the brine purification system.

[0062] Dissolution unit

[0063] The carbonate-salt mixture produced in the anaerobic pyrolysis unit is introduced into the dissolution unit of the brine purification system via the discharge unit, where water is added and stirred to dissolve the carbonate-salt mixture. Specifically, after the carbonate-salt mixture is cooled to approximately 50°C, it falls into a salt dissolving tank equipped with a stirring device, where water is added to dissolve it. The resulting saturated salt solution then enters the filtration unit.

[0064] Filter unit

[0065] The saturated salt solution produced by the dissolving unit is introduced into the filtration unit. First, carbon particles in the saturated salt solution are filtered out by a sieve. The solution then passes through a magnesium and phosphorus removal tank and a calcium removal tank to remove calcium and magnesium ions. Finally, it undergoes microfiltration membrane treatment. The purified salt solution then enters the refining and separating system. Specifically, the saturated salt solution overflowing from the dissolving tank is pumped into the brine tank, and then sent to the magnesium and phosphorus removal tank, where NaOH and Ca(OH)₂ are added. The NaOH reacts with the magnesium in the brine... 2+ Fe 2+ Fe 3+ Cu 2+ When metal ions react, hydroxide precipitates are formed; Ca(OH)₂ reacts with PO₄⁻ in the salt water. 3- The reaction produces Ca3(PO4)2 precipitate.

[0066] If the solution still contains a certain amount of Ca after the reaction 2+ In order to make Ca 2+ To remove calcium, excess Na₂CO₃ is added to the calcium removal tank. The Na₂CO₃ reacts with the calcium in the brine.2+ The reaction produces CaCO3 precipitate. After the reaction, the solution enters a hydrocyclone to remove undissolved salt particles before entering a microfiltration membrane system. The filtrate then enters a purification and salt separation system. The backwash sludge from the microfiltration membrane system is pumped to a plate and frame filter press via a diaphragm pump. Waste carbon residue is outsourced for treatment, and the filtrate is returned to the salting tank.

[0067] Refined Salt Separation System

[0068] The salt solution, after impurity removal by the filtration unit, is introduced into a refined salt separation system. Salts are classified according to their components. For single salts, an evaporation-drying process is used to ensure the resulting single salt meets national or industry standards. For mixed salts with multiple components, a controlled crystallization separation technique is employed, separating and purifying the salts based on their different solubilities in water, ensuring the resulting salt meets national or industry standards and achieving productization and resource utilization. Specifically, the mixed salt solution utilizes physicochemical methods to separate and purify different salts, with specific analysis tailored to the specific type of mixed salt.

[0069] The following explanation uses mixed salt treatment of sodium chloride and sodium sulfate, and single salt treatment of sodium sulfate as examples.

[0070] Sodium chloride-sodium sulfate mixed salt treatment process

[0071] Using a sodium chloride-sodium sulfate mixed salt solution obtained from high-concentration organic saline wastewater through a high-throughput direct pyrolysis system and a brine purification system as raw material, the sodium chloride and sodium sulfate are effectively separated in the mixed brine through a main process path of "freezing to produce nitrate - evaporation to produce salt," respectively preparing sodium sulfate (sodium sulfate decahydrate) and sodium chloride brine. The sodium sulfate can be fed into the sodium sulfate evaporation tank as a raw material for "evaporation to produce nitrate," yielding industrial-grade sodium sulfate (anhydrous sodium sulfate). The sodium chloride brine then enters an evaporation crystallization drying system to obtain dried sodium chloride.

[0072] Sodium sulfate treatment process

[0073] The sodium sulfate brine obtained after the high-concentration organic salt waste liquid is treated by a high-throughput direct pyrolysis system and a brine impurity removal system is introduced into a sodium sulfate evaporation feed tank. Through the main process path of "evaporation to produce nitrate", the sodium sulfate in the brine is crystallized and extracted by an MVR evaporation crystallization device to produce industrial-grade sodium sulfate (anhydrous sodium sulfate) product.

[0074] This invention provides a method for the resource-based treatment of high-concentration organic saline wastewater. This method, based on the aforementioned resource-based treatment system, includes the following steps:

[0075] a. The high-concentration organic saline waste liquid is pumped to a high-throughput direct pyrolysis system. The high-throughput direct pyrolysis system includes a feeding unit, an anaerobic pyrolysis unit, an oxidation unit, a tail gas treatment unit, and a discharge unit, and the following steps are performed:

[0076] 1) The high-concentration organic salt waste liquid is sent to the anaerobic pyrolysis unit through the feeding unit. Under anaerobic conditions, the high-concentration organic salt waste liquid and the high-temperature flue gas generated by the oxidation unit undergo rapid cracking reaction. The reaction time is 2-3 seconds and the reaction temperature is about 1200℃. The resulting carbon and salt mixture and cracked gas are generated. The generated carbon and salt mixture is introduced into the discharge unit, and the generated cracked gas enters the oxidation unit.

[0077] 2) The pyrolysis gas generated in step 1) is introduced into the oxidation unit, where it undergoes an oxidation reaction with pure oxygen. Part of the resulting high-temperature flue gas is introduced into the anaerobic pyrolysis unit to continue the pyrolysis reaction with the feed material, forming a loop. The other part enters the tail gas treatment unit.

[0078] 3) The other part of the high-temperature flue gas generated in step 2) is introduced into the tail gas treatment unit for treatment. The gas first enters the secondary oxidation chamber for pure oxygen oxidation, the temperature is controlled at 1100℃-1200℃, the oxidation time is greater than 2s, and the treated flue gas then goes through SNCR denitrification, rapid cooling alkaline washing, dust removal and other steps to make the flue gas meet the emission standards.

[0079] b. The solid carbonate mixture generated in step 1) is fed into the brine purification system through the discharge unit for treatment. The brine purification system includes a dissolution unit and a filtration unit, and performs the following steps:

[0080] 4) The carbonate-salt mixture generated in step 1) is introduced into the dissolution unit of the brine purification system. Water is added to the carbonate-salt mixture and stirred to dissolve it. The resulting saturated salt solution enters the filtration unit.

[0081] 5) The saturated salt solution generated in step 4) is introduced into the filtration unit. First, the carbon particles in the saturated salt solution are filtered out by sieve filtration. Then, the solution passes through the magnesium and phosphorus removal tank and the calcium removal tank to remove calcium and magnesium ions present in the solution. Finally, it undergoes microfiltration membrane treatment. The purified salt solution enters the refining and separating salt system.

[0082] c. Introduce the purified salt solution from step 5) into the refining and separating salt system, classify it according to salt components. For single salt components, use an evaporation and drying process to ensure that the resulting single salt meets national or industry standards. For mixed salts with multiple components, use controlled crystallization separation technology to separate and purify the salts according to their different solubilities in water, so that the resulting salt meets national or industry standards, and realizes productization and resource utilization.

[0083] The present invention will now be described in detail with reference to specific embodiments.

[0084] Taking a high-concentration organic saline waste liquid from a chemical plant as an example, its original waste liquid has a COD of 318,720 mg / L, an ammonia nitrogen of 4,245 mg / L, a total nitrogen of 8,239 mg / L, and the salt component is mainly sodium chloride.

[0085] Using the above-mentioned treatment system, the high-concentration organic saline waste liquid is treated according to the following steps:

[0086] a. The high-concentration organic saline waste liquid is pumped to a high-throughput direct pyrolysis system. The high-throughput direct pyrolysis system includes a feeding unit, an anaerobic pyrolysis unit, an oxidation unit, a tail gas treatment unit, and a discharge unit, and the following steps are performed:

[0087] 1) The high-concentration organic salt waste liquid is sent to the anaerobic pyrolysis unit through the feeding unit. Under anaerobic conditions, the high-concentration organic salt waste liquid and the high-temperature flue gas generated by the oxidation unit undergo rapid cracking reaction. The reaction time is 2-3 seconds and the reaction temperature is about 1200℃, generating a mixture of carbon and salt as well as cracked gas. The generated mixture of carbon and salt is introduced into the discharge unit, and the generated cracked gas enters the oxidation unit.

[0088] 2) The pyrolysis gas generated in step 1) is introduced into the oxidation unit, where it undergoes an oxidation reaction with pure oxygen. Part of the resulting high-temperature flue gas is introduced into the anaerobic pyrolysis unit to continue the pyrolysis reaction with the feed material, forming a loop. The other part enters the tail gas treatment unit.

[0089] 3) The other part of the high-temperature flue gas generated in step 2) is introduced into the tail gas treatment unit for treatment. The gas first enters the secondary oxidation chamber for pure oxygen oxidation, the temperature is controlled at 1100℃-1200℃, the oxidation time is greater than 2s, and the treated flue gas then goes through SNCR denitrification, rapid cooling alkaline washing, dust removal and other steps to make the flue gas meet the emission standards.

[0090] b. The solid carbonate mixture generated in step 1) is fed into the brine purification system through the discharge unit for treatment. The brine purification system includes a dissolution unit and a filtration unit, and performs the following steps:

[0091] 4) The carbonate-salt mixture generated in step 1) is introduced into the dissolution unit of the brine purification system. Water is added to the carbonate-salt mixture and stirred to dissolve it. The resulting saturated salt solution enters the filtration unit.

[0092] 5) The saturated salt solution generated in step 4) is introduced into the filtration unit. First, the carbon particles in the saturated salt solution are filtered out by sieve filtration. Then, the solution passes through the magnesium and phosphorus removal tank and the calcium removal tank to remove calcium and magnesium ions present in the solution. Finally, it undergoes microfiltration membrane treatment. The purified salt solution enters the refining and separating salt system.

[0093] c. The purified salt solution from step 5) is introduced into a refining and separating salt system. The main component of the salt solution is sodium chloride. The sodium chloride solution is then processed through an evaporation, crystallization and drying system to obtain dried sodium chloride product.

[0094] After treatment using the above system and methods, the COD removal rate in the waste liquid reached 99.9%. The COD in the filtered salt solution was measured to be 15 mg / L, ammonia nitrogen 1.0 mg / L, and total nitrogen 2.89 mg / L. The sodium chloride obtained after evaporation and drying met the first-grade standard of refined industrial salt - industrial dry salt in GB / T5462-2015 "Industrial Salt", realizing resource utilization and productization. Furthermore, this method offers stable treatment results and low system operating costs, with the cost of treating one ton of waste liquid controlled at 600-700 yuan.

[0095] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the technical concept of the present invention, all of which fall within the scope of protection of the present invention.

Claims

1. A method for resource-based treatment of high-concentration organic saline wastewater, characterized in that, Includes the following steps: (a) Under anaerobic conditions, high-concentration organic salt waste liquid is contacted with high-temperature flue gas to undergo a cracking reaction, yielding a carbon-salt mixture and cracked gas; The pyrolysis reaction time is 2-3 seconds, and the pyrolysis reaction temperature is 1100-1300℃. (b) The pyrolysis gas in (a) is reacted with pure oxygen to produce high-temperature flue gas. Part of the high-temperature flue gas is returned to (a) to react with the high-concentration organic salt waste liquid to produce a pyrolysis reaction. (c) Treat the remaining high-temperature flue gas from (b) as exhaust gas; (d) Dissolve the carbon-salt mixture in (a) in water, and then sequentially process it through carbon particle removal, addition of NaOH and Ca(OH)2, calcium removal and membrane filtration to obtain a purified salt solution. The temperature of the carbonate-salt mixture is 40-60℃; Mg in the brine is removed by adding NaOH and Ca(OH)2. 2+ Fe 2+ Fe 3+ Cu 2+ At least one of the following; further removal of Ca by adding Na2CO3. 2+ The salt solution is filtered through a microfiltration membrane to obtain impurities, and then sorted and recovered in (e). (e) The salt solution obtained in (d) is recovered according to the salt components and purified to obtain a single salt product.

2. The resource recovery method according to claim 1, characterized in that, (a) The carbon-salt mixture and the pyrolysis gas after the pyrolysis reaction are cooled to 500-600℃ through heat exchange.

3. The resource recovery method according to claim 2, characterized in that, The heat exchanged in (a) serves as the heat source for the oxidation reaction in (b).

4. The resource recovery method according to claim 1, characterized in that, (b) The temperature of the pure oxygen oxidation reaction is 1200℃-1300℃, and the reaction time is 2-3s.

5. The resource recovery method according to claim 1, characterized in that, (c) The exhaust gas treatment includes: the high-temperature flue gas is successively subjected to pure oxygen oxidation, denitrification, rapid cooling alkaline washing and dust removal before being discharged.

6. The resource recovery method according to claim 5, characterized in that, The denitrification process is SNCR denitrification.

7. The resource recovery method according to claim 5, characterized in that, (c) The temperature of pure oxygen oxidation in the exhaust gas treatment is at least 1100-1200℃, the oxygen content of dry flue gas is >6%, and the pure oxygen oxidation time is 2-3s.

Images