A system and method for disposing of high-salt high-calcium magnesium wastewater and miscellaneous salts

Abstract

The present application relates to a kind of high salt high calcium magnesium wastewater and miscellaneous salt disposal system and method, by oxidation, adsorption, adjustment, filtration purification after high salt high calcium magnesium wastewater, into nanofiltration unit 1 and separate out polyvalent salt, nanofiltration concentrated water is removed by gypsum crystallization method and ammonium carbonate method, after purification, into nanofiltration unit 2 and separate, nanofiltration concentrated liquid is reacted with after pyrolysis miscellaneous salt and forms gypsum, solution evaporation crystallization produces sodium chloride and gypsum, sodium chloride enters the production of sodium carbonate salt in alkali unit, and the production of ammonia-containing mother liquor is recycled back to alkali unit by hot ammonia extraction, and evaporation crystallization mother liquor is recycled by hot ammonia, and forms ammonium carbonate with CO2 to soften nanofiltration unit 1 concentrated liquid, the water produced by nanofiltration unit 1 and 2 is sequentially passed through concentration unit 1 and 2, and the concentrated liquid containing sodium chloride is passed into the alkali unit to produce alkali, and the gypsum produced by the system is dehydrated after purification to form gypsum product. The present application solves the problem of high-salt high-hardness wastewater and miscellaneous salt disposal, and has the advantages of low energy consumption and strong economy.

Description

Technical Field

[0001] This invention belongs to the field of environmental wastewater treatment, specifically referring to the resource-based treatment of high-salt, high-calcium, and high-magnesium wastewater and zero-discharge wastewater containing miscellaneous salts. Background Technology

[0002] my country has a complete high-salinity wastewater technology system, and its overall process is at the international leading level.

[0003] Zero-discharge salt separation technology for high-salinity wastewater involves high investment, high operating costs, and a large amount of hazardous waste and mixed salts at the end of the process.

[0004] In addition to the issues mentioned above, my country faces several bottlenecks in its zero-discharge technology for high-salinity wastewater, primarily in the area of ​​high-salinity, high-hardness wastewater. This wastewater exhibits high calcium and magnesium ion content, leading to large amounts of softening agents required for the "dual-alkali method," resulting in substantial sludge production and poor operational economics. Sources of this wastewater include power plant desulfurization wastewater, high-calcium wastewater from the new energy industry, ammonia stripping wastewater from the soda ash production industry, concentrated water from zero-discharge multi-stage reverse osmosis systems, acid-base neutralization wastewater from the titanium dioxide industry and other metallurgical and chemical industries, high-salinity mine wastewater, and evaporation pond wastewater. Most of these wastewaters contain over 500 mg / L of calcium ions. Taking multi-stage reverse osmosis concentrated brine as an example, the membranes in these high-salinity wastewater progressively concentrate the solution, leading to the gradual accumulation and concentration of organic matter. This results in a high-salinity, high-COD, and high-calcium-magnesium salt solution, further causing membrane fouling, scaling during evaporation and crystallization, difficulties in control, low salt separation efficiency, and large amounts of hazardous waste and mixed salts in subsequent processes such as membrane separation.

[0005] Taking the domestic coal chemical industry as an example, a large-scale coal chemical plant in Ningxia, China, uses a dual-membrane reverse osmosis system to process wastewater with zero discharge. The concentrated wastewater enters a nanofiltration system for salt separation. After cooling, sodium sulfate is precipitated, and the cooling mother liquor is recycled to the front of the nanofiltration system, forming a closed-loop structure. Although catalytic oxidation and activated carbon adsorption are added to the closed-loop structure, the limited removal capacity cannot solve the problem of impurity enrichment. This results in the continuous enrichment of large amounts of organic matter, calcium and magnesium cations, etc., leading to low cooling crystallization efficiency, loss of salt separation function of the nanofiltration system, and continuous expansion of the circulating mother liquor, resulting in a passive situation where continuous operation is impossible. Therefore, the unreasonable salt separation, low efficiency, and high operating energy consumption cannot be fundamentally changed. Similar processes in China have all experienced the same problems. Therefore, the system design needs to be optimized to avoid the risk of system collapse caused by the accumulation of cyclical substances.

[0006] Taking power plant desulfurization wastewater as an example, its calcium ion concentration is close to saturation, and the magnesium ion content in the solution is not less than 500 ppm. The membrane process and softening process are expensive and generate a large amount of sludge. As a result, the zero-discharge technology route for power plant wastewater has been avoided. The basic approach is to concentrate flue gas and then dry the waste salts before they enter the fly ash system. This is essentially a pollutant transfer process and not a true zero-discharge solution.

[0007] In my country's new energy silicon industry, the high-calcium wastewater generated is mainly composed of calcium chloride. The softening method is used, and the treatment cost per ton of water exceeds 50 yuan. Other acid and alkali neutralized wastewater, high-mineralized mine water wastewater, etc., all face the bottleneck problem of high calcium ion content and high actual operating costs in their treatment.

[0008] my country has made significant efforts to adapt to the characteristics of this wastewater, and enhancing the antifouling ability of membranes has been a focus for various technical units. Domestic manufacturers are constantly exploring new technologies in membrane performance research and development, resulting in applications such as salt-resistant and fouling-resistant flat sheet membranes and spiral wound membranes. Among them, the key research and development direction is based on high-pressure flat sheet membrane technology (DTRO), which has shown significant antifouling ability in the concentration of high-salt, high-COD, and high-hardness wastewater. However, its high investment cost and persistently high operating cost limit the widespread application of this type of membrane. The hardness and organic matter enrichment of the concentrated high-salt solution are further enhanced, and it is still impossible to avoid the need for further softening and purification measures.

[0009] The salt products of zero-discharge high-salinity wastewater in my country consist of three parts: sodium sulfate, sodium chloride, and miscellaneous salts.

[0010] In addition, my country generates a large amount of zero-emission mixed salts, mostly consisting of zero-emission mixed salt systems and a portion of zero-emission mixed salt systems. The stock is substantial. These salts have high organic content and high disposal costs. Currently, the main processes are high-temperature pyrolysis carbonization of waste salts from natural gas combustion, anaerobic carbonization, and solution spray incineration. The disposal cost per ton of salt is approximately RMB 800 or more, resulting in significant exhaust emissions, numerous secondary pollution treatment devices, and a large workload for maintenance.

[0011] Therefore, considering the current situation of high-salt wastewater treatment in my country, the treatment of high-salt, high-calcium, and magnesium wastewater, as well as the treatment of evaporative crystallized miscellaneous salts, are the most difficult technical aspects to achieve zero discharge of high-salt wastewater in my country. The existing domestic technical system suffers from several problems. Firstly, the unreasonable process design leads to high system operating costs and significant technical difficulties. Secondly, there is a lack of effective technologies and methods for the harmless and high-value-added treatment of waste salts.

[0012] Based on the above, the content of this invention is described as follows:

[0013] 1. A treatment system for high-salt, high-calcium-magnesium wastewater and miscellaneous salts, characterized in that it comprises: an oxidation unit, an activated carbon adsorption unit, an equalization tank 1, a sand filtration unit, an ultrafiltration unit 1, a reagent mixing unit, a nanofiltration unit 1, an equalization tank 2, a clarification tank 1, a softening reaction tank, a clarification tank 2, a media filtration tank, an ultrafiltration unit 2, a nanofiltration unit 2, a carbonizer, a cooler, a mother liquor ammonia removal unit, a slurry dewatering unit, a drying unit, a miscellaneous salt deheating unit, a waste heat recovery unit, a reaction tank, a clarification tank 3, an evaporation crystallization unit, an alkali production unit, an ammonia recovery unit, a buffer tank, a concentration unit 1, a concentration unit 2, a deep desilication unit, a gypsum deposition tank, a gypsum washing unit, a plate and frame filter press 1, and a plate and frame filter press 2;

[0014] The high-salt wastewater enters the inlet of the oxidation unit, the outlet of the oxidation unit is connected to the inlet of the activated carbon adsorption unit, the outlet of the activated carbon adsorption unit is connected to the first inlet of the equalization tank 1, the outlet of the equalization tank 1 is connected to the inlet of the sand filter unit, and a second inlet for adding reagents is left at the top of the equalization tank 1.

[0015] The outlet of the sand filter unit is connected to the inlet of the ultrafiltration unit 1, the outlet of the ultrafiltration unit 1 is connected to the first inlet of the reagent mixing unit, the second inlet of the reagent mixing unit has a reagent addition port, the outlet of the reagent mixing unit is connected to the inlet of the nanofiltration unit 1, the first outlet of the nanofiltration unit 1 is connected to the first inlet of the equalization tank 2, and the second outlet of the nanofiltration unit 1 is connected to the inlet of the deep desilication unit.

[0016] The second inlet of the equalization tank 2 is connected to the second outlet of the gypsum deposition unit, the third inlet of the equalization tank 2 is provided with a reagent addition port, the outlet of the equalization tank 2 is connected to the first inlet of the clarification tank 1, the fourth inlet of the equalization tank 2 is connected to the second outlet of the clarification tank 1, the second inlet of the clarification tank 1 is provided with a reagent addition port, and the first outlet of the clarification tank 1 is connected to the first inlet of the softening reaction tank.

[0017] The second inlet of the softening reaction tank is connected to the outlet of the carbonizer, the outlet of the softening reaction tank is connected to the inlet of the clarifier 2, the first outlet of the clarifier 2 is connected to the inlet of the media filter, and the second outlet of the clarifier 2 is the calcium carbonate outlet.

[0018] The outlet of the media filter is connected to the inlet of the ultrafiltration unit 2, the outlet of the ultrafiltration unit 2 is connected to the inlet of the nanofiltration unit 2, the first outlet of the nanofiltration unit is connected to the first inlet of the reaction tank, and the second outlet of the nanofiltration unit 2 is connected to the second inlet of the concentration unit 2.

[0019] The mixed salt enters the mixed salt pyrolysis inlet, the mixed salt pyrolysis outlet is connected to the waste heat recovery inlet, and the waste heat recovery outlet is connected to the second inlet of the reaction tank.

[0020] The outlet of the reaction tank is connected to the inlet of the clarifier 3, and the third inlet of the reaction tank is connected to the second outlet of the ammonia recovery unit.

[0021] The first outlet of the clarification tank 3 is connected to the inlet of the evaporation and crystallization unit, and the second outlet is connected to the second inlet of the gypsum deposition unit.

[0022] The first outlet of the evaporation and crystallization unit is connected to the third inlet of the alkali production unit. The second outlet of the evaporation and crystallization unit produces sodium chloride. The third outlet is connected to the third inlet of the mother liquor deammoniation unit. The fourth outlet is connected to the second inlet of the gypsum deposition unit.

[0023] The first outlet of the alkali production unit is connected to the second inlet of the ammonia recovery unit, and the second outlet of the alkali production unit outputs sodium carbonate or sodium bicarbonate.

[0024] The first inlet of the alkali production unit is connected together with the first outlet of the ammonia recovery unit and the outlet of the buffer tank;

[0025] Calcium oxide or calcium carbide waste residue is introduced into the first inlet of the ammonia recovery unit.

[0026] The first outlet of the deep desilication unit discharges desilication impurities, the second outlet is connected to the inlet of the concentration unit 1, the outlet of the concentration unit 1 is connected to the inlet of the concentration unit 2, the outlet of the concentration unit 2 is connected to the inlet of the buffer pool, the third inlet of the concentration unit 2 has an inlet for steam or high-temperature hot water, and the second outlet of the concentration unit 2 has a outlet for condensate.

[0027] The first outlet of the gypsum sedimentation tank is connected to the inlet of plate and frame filter press 1, the first outlet of plate and frame filter press 1 is connected to the gypsum washing inlet, the first outlet of the gypsum washing unit is connected to the inlet of plate and frame filter press 2, the second outlet of the gypsum washing unit outputs washing liquid, the first outlet of plate and frame filter press 2 outputs gypsum, and the second outlet outputs filter liquid.

[0028] CO2 and ammonia water enter the first inlet of the carbonizer, the second inlet of the carbonizer is connected to the outlet of the cooler, and the inlet of the cooler is connected to the first outlet of the mother liquor deammoniation.

[0029] The mother liquor deammoniation first inlet is supplied with calcium oxide, the second inlet is supplied with steam, the second outlet is connected to the slurry dewatering inlet, and the slurry dewatering outlet is connected to the drying inlet.

[0030] The aforementioned system for treating high-salt, high-calcium, and high-magnesium wastewater and miscellaneous salts is characterized in that the carbonizer consists of a tower-type carbonization tower or a tank-type carbonization tank and a neutralization tank for ammonia water and carbonization slurry.

[0031] The aforementioned system for treating high-salt, high-calcium, and high-magnesium wastewater and miscellaneous salts is characterized in that the gypsum cleaning process comprises a slurry suspension cleaning tank and a slurry crystallization tank.

[0032] The aforementioned treatment system for high-salt, high-calcium, and magnesium wastewater and miscellaneous salts includes a reagent mixing unit that is a rapid pipeline mixer with a high-frequency acoustic oscillator welded to the outer wall of the pipeline.

[0033] The aforementioned system for treating high-salt, high-calcium, and high-magnesium wastewater and miscellaneous salts is characterized in that the alkali production unit is equipped with a traditional ammonia-soda process or a combined alkali process system.

[0034] The high-salt, high-calcium, and high-magnesium wastewater treatment system is characterized in that the concentrated liquid from the nanofiltration unit 1 enters the equalization tank 2, which is a structure of multiple parallel or series-connected stirred tanks equipped with agitators.

[0035] The aforementioned treatment system for high-salt, high-calcium, and high-magnesium wastewater is characterized in that the pyrolysis of mixed salts uses an electromagnetic rotary kiln heater, and the waste heat recovery uses a rotary drum waste heat recovery unit.

[0036] The treatment system for high-salt, high-calcium, and high-magnesium wastewater is characterized in that the dehydration of the mother liquor slurry after ammonia extraction is carried out using a steam-heated negative pressure vacuum evaporator, and the drying is carried out using one of a drum dryer, a paddle stirrer dryer, or a disc dryer.

[0037] The aforementioned treatment system for high-salt, high-calcium, and high-magnesium wastewater uses nanofiltration unit 1 and nanofiltration unit 2, which employ either antifouling spiral wound nanofiltration membranes or high-pressure disc antifouling nanofiltration membranes, or a combination of both.

[0038] The method for treating high-salt, high-calcium, and high-magnesium wastewater is characterized by comprising:

[0039] The high-salt wastewater refers to high-salt, high-calcium-magnesium concentrated water that has undergone at least two consecutive stages of concentration via reverse osmosis membrane, or one or more of the following mixed waters after filtration and purification: desulfurization wastewater, concentrated brine from nanofiltration, industrial acid-base neutralization wastewater, evaporation-concentrated mixed salt wastewater, evaporation-concentrated mother liquor, and high-mineralization mine water. The soluble salt content of the wastewater is not less than 10,000 mg / L.

[0040] The oxidation unit employs one or more combinations of ozone catalytic oxidation, Fenton oxidation, electrochemical oxidation, sodium hypochlorite, and hydrogen peroxide oxidation, with an oxidation removal rate of not less than 50%.

[0041] The activated carbon adsorption unit uses granular activated carbon or powdered activated carbon, preferably powdered activated carbon. The organic matter removal rate of the wastewater COD after passing through the activated carbon is not less than 70%.

[0042] The pH is adjusted to be below 7 by adding either hydrochloric acid or sulfuric acid to the conditioning tank 1, and more preferably to a pH of 6.5.

[0043] After being filtered and purified by sand filtration unit 1 and ultrafiltration unit 1, the effluent SS is below 3ppm.

[0044] The organic scale inhibitor added in the reagent mixing unit refers to an organic chelating agent, which includes at least three of the following: aminotrimethylene phosphonic acid (ATMP), hydroxyethylidene diphosphonic acid (HEDP), polystyrene sulfonate, copolymer of sulfonic acid and acrylic acid, aminopropanesulfonic acid-acrylic acid copolymer, and polyacrylic acid-2-acrylamide methylpropanesulfonic acid group, forming a compound scale inhibitor. The concentration of the compound scale inhibitor added is 5 to 15 ppm.

[0045] The water production efficiency of the nanofiltration unit 1 is not less than 65%.

[0046] In the equalization tank 2, a coagulation and sedimentation reaction is carried out by adding lime slurry, scale inhibitor deactivator, and coagulant. The scale inhibitor deactivator refers to one or more combinations of trivalent metal ion (e.g., Fe3+, Al3+) compounds, and its addition amount is 10-30 ppm. The wastewater retention time in the equalization tank 2 is not less than 1 hour, preferably 1.5 hours.

[0047] When the pH of the wastewater in the equalization tank 2 is above 10, the scale inhibitor loses its chelating effect on calcium ions. After the solubilization effect of the agent fails, the supersaturated calcium sulfate dissolves and precipitates out, forming gypsum solid suspension. The slurry waste brine containing calcium sulfate solid in the equalization tank 2 enters the clarification tank 1.

[0048] The wastewater retention time in the clarifier 1 is not less than 1 hour, and the flow rate of the slurry at the bottom of the clarifier 1 returned to the equalization tank 2 is not less than 0.1% of the wastewater flow rate entering the clarifier 1.

[0049] The supernatant from clarifier 1 enters softening reaction tank, where a thick ammonium carbonate slurry from the carbonizer is introduced. The reactions that occur are as follows: (NH4)2CO3 + CaCl2 = 2NH4Cl + CaCO3↓; CaSO4 + 2NH3 + CO2 + H2O = (NH4)2SO4 + CaCO3↓

[0050] The wastewater solution after the softening reaction enters the clarification tank 2. After clarification for no less than 1 hour, the clear liquid enters the media filter. The media filter refers to either a sand filter or a multi-media filter.

[0051] The brine filtered by the media filter enters the ultrafiltration unit 2, where it undergoes deep filtration, resulting in effluent SS levels below 3 ppm.

[0052] The nanofiltration unit 2 has a water production rate of not less than 50%, and the separated water is a monovalent sodium chloride solution that enters the concentration unit 2.

[0053] The concentrated water from nanofiltration unit 2 enters the reaction tank, and the reaction time in the reaction tank is no less than 2 hours.

[0054] The reaction tank consists of at least two tanks connected in series. The reaction tank is a stirred reaction system. The sodium sulfate in the reaction tank originates from pyrolysis and waste heat recovery of miscellaneous salts. It reacts with calcium chloride slurry or a mixed salt solution of calcium chloride and sodium chloride from the ammonia recovery unit. The reaction within the reaction tank is as follows:

[0055] Na2SO4+CaCl2=CaSO4↓+2NaCl;

[0056] The slurry from the reaction tank outlet enters the clarifier 3 and the solution stays for no less than 1 hour.

[0057] The supernatant from the clarification tank 3 enters the evaporation crystallization unit. The evaporation crystallization is one or a combination of two types of multi-effect evaporation crystallization or MVR evaporation crystallization. The evaporation crystallization temperature is between 65 and 95°C. The evaporation crystallization adopts the gypsum seed crystallization method for salt separation and crystallization. The heater and heat exchanger adopt three-phase flow heat exchange and anti-scaling technology.

[0058] The evaporation and crystallization process produces gypsum, sodium chloride, and mother liquor, with a portion of the sodium chloride entering the alkali production unit.

[0059] After the reaction in the alkali production unit, the ammonium chloride mother liquor or ammonium chloride slurry enters the ammonia recovery unit, which employs either steam stripping or thermal evaporation and concentration to extract ammonia.

[0060] The waste liquid after ammonia recovery is either ammonia-soda waste liquid or calcium chloride waste liquid, and the slurry enters the reaction tank for reaction.

[0061] The ammonia water or gaseous ammonia mixture from the ammonia recovery unit is returned to the alkali production unit.

[0062] The gypsum sedimentation tank receives gypsum slurry from the equalization tank 2, gypsum slurry separated by evaporation and crystallization, and gypsum slurry after reaction in the clarification tank 3. After sedimentation, it enters the plate and frame filter press 1 unit, is dewatered by the plate and frame filter press, and enters the gypsum washing unit. After washing, the gypsum slurry enters the plate and frame filter press 2 for dewatering to below 50%.

[0063] The water produced by the nanofiltration unit 1 enters the deep desilication unit, where desilication is carried out by one or more combinations of chemical desilication, resin adsorption, or electrochemical coagulation.

[0064] The desilication-treated sodium chloride solution enters concentration unit 1, which employs one or more combinations of reverse osmosis concentration or electrodialysis concentration devices.

[0065] The concentrated sodium chloride solution enters concentration unit 2, which uses a low-temperature residual heat method for evaporation and concentration, resulting in a solution pH value below 7.

[0066] The concentrated salt solution from concentration unit 2 enters the buffer tank and then the alkali production unit. The evaporation and crystallization mother liquor contains ammonia ions, a small amount of sulfate ions, and the remainder consists of chloride ions, nitrates, etc., and enters the mother liquor deammoniation unit. The mother liquor deammoniation unit uses steam stripping or evaporation for deammoniation, and the alkaline additive is quicklime or calcium carbide waste residue.

[0067] The deammoniation-treated vaporized ammonia is cooled to form ammonia water, which then enters a carbonizer. The carbonizer is either a tower or a tank structure, and the following reaction occurs inside: 2NH3·H2O + CO2 = (NH4)2CO3 + H2O

[0068] The mother liquor after ammonia extraction enters the slurry dewatering unit for further drying and distribution.

[0069] Compared with existing technologies for treating high-salt, high-calcium, and high-magnesium wastewater and miscellaneous salts in my country, the advantages and positive effects of this invention are as follows:

[0070] 1. This invention proposes a synergistic treatment method for high-salt, high-calcium, and magnesium wastewater and miscellaneous salt systems. It is applicable to the treatment of high-salt, high-calcium, and magnesium wastewater and the resource utilization of hazardous waste miscellaneous salts. The wastewater involved includes high-difficulty wastewater treatment processes such as reverse osmosis multi-stage concentration wastewater, hydrometallurgical acid-base neutralization water, titanium dioxide acidic wastewater, polycrystalline silicon, monocrystalline silicon neutralization of high-calcium wastewater, power plant desulfurization wastewater, ammonia stripping wastewater treatment in the ammonia-soda process, and zero discharge of mine water wastewater. The solution is to use gypsum seeding and nanofiltration separation, and to treat the wastewater by combining gypsum crystallization precipitation with a softening method based on ammonia cycle carbonization to produce ammonium carbonate to precipitate calcium ions. This eliminates or reduces the use of traditional soda ash and caustic soda reagents, saving softening reagent costs and improving the economic efficiency of system operation.

[0071] 2. The technological innovation of the softening process in this invention lies in using ammonia as a medium to absorb CO2 and precipitate calcium and magnesium ions in high-salt wastewater as carbonates. Ammonia recovery is achieved by reacting quicklime with the mother liquor from evaporation and crystallization. While precipitating ammonia, the mother liquor is further purified, causing residual sulfate and polyvalent cations in the mother liquor to precipitate and form general solid waste, thus reducing the amount of mixed salts discharged. Only a small amount of mixed salts are dried and disposed of, thereby significantly reducing the cost of hazardous waste mixed salt disposal. At the same time, ammonia is recycled in the nanofiltration unit and the alkali production unit, which softens the wastewater, realizes the circulation of ammonia in the system, and solidifies CO2, achieving multiple benefits and outstanding economic efficiency, while ensuring the purity of the evaporated and crystallized sodium chloride.

[0072] 3. This invention abandons the traditional hot and cold method combined with salt separation process. In the traditional salt separation process, the sodium sulfate content in the mixed salt is about 40%, the sodium chloride content is about 50%, and only about 10% is composed of nitrates, potassium salts, metal cations, etc. Through the implementation of this technology, complete salt separation is achieved. Compared with the existing mixed salt system, the salt separation efficiency of sodium sulfate and sodium chloride in the mixed salt system is further improved by 80%, and only a small amount of nitrates, potassium salts, etc. are enriched and mixed salts are separated. Therefore, the problem of high disposal cost of zero-discharge hazardous waste mixed salt is greatly reduced. Because the calcium method is used to separate sulfate, gypsum is a slightly soluble substance. Under high salt system, its solubility is in the range of 0.2 to 0.5 g / 100 g water, which is in the slightly soluble category. Most of it will precipitate. Therefore, through the reaction principle of sodium sulfate and calcium chloride, sulfate ions are precipitated, and the salt separation is more thorough.

[0073] 4. Through the resource-based treatment of waste salt, the calcium sulfate formed undergoes high purity processing via gypsum deposition unit, high-efficiency reagent-assisted sedimentation, and temperature-controlled crystallization technology. This significantly enhances its economic value, resulting in gypsum products. Simultaneously, the sodium carbonate or sodium bicarbonate produced in the alkali-making unit enjoys high market profits and outstanding economic viability. Based on average market prices, the by-product sodium sulfate costs 100 yuan / ton, sodium chloride 50 yuan / ton, and the processing cost of miscellaneous salts is no less than 1600 yuan / ton. In contrast, sodium carbonate costs 1600 yuan / ton. The economic advantage of producing soda ash or sodium bicarbonate is self-evident.

[0074] 5. This project utilizes a high-salt wastewater and waste salt coupled CO2 process, combined with traditional ammonia-soda or combined alkali production processes, to solidify CO2 into sodium carbonate and sodium bicarbonate, while calcium ions partially form calcium carbonate. This reduces production costs and solidifies CO2, highlighting the innovativeness of the technology. Furthermore, the combined ammonia-soda or combined alkali production processes are traditional and mature technologies, ensuring reliable technical support and ease of implementation for this method.

[0075] 6. This invention proposes a synergistic resource utilization method that combines the treatment of calcium carbide waste residue with high-salt wastewater and waste salt, producing sodium carbonate or sodium bicarbonate and high-purity gypsum. While treating brine and miscellaneous salts, the waste calcium carbide waste residue can also be treated, turning waste into treasure.

[0076] 7. This invention proposes a calcium sulfate crystallization precipitation process based on nanofiltration concentration and salt separation. By adding a composite combination of commonly used organic scale inhibitors, inorganic matter is effectively controlled to prevent scaling within a wide concentration range, and calcium sulfate is solubilized. Therefore, the concentration ratio of the initial calcium sulfate solution entering the nanofiltration membrane is increased by more than 4 times. Under the chelating effect of the reagents, calcium sulfate is ensured not to precipitate.

[0077] 8. Considering the actual production unit of this invention, there will be a large amount of low-grade waste heat and medium-high temperature hot water. By utilizing the low-temperature waste heat of this part of the process to concentrate brine through low-temperature flash evaporation, the low-quality waste heat is utilized in a high-efficiency cascade manner, thereby achieving the purpose of energy saving. This completely solves the problem of energy waste caused by the ineffective utilization of low-grade waste heat in the traditional alkali production process, and further reduces heat loss.

[0078] 9. The sodium sulfate and calcium chloride reaction unit of the present invention adopts a multi-stage reaction precipitation combination technology, which solves the problems of fine gypsum crystals, long precipitation time and low reaction transfer rate after high concentration of calcium chloride reacts with sodium sulfate.

[0079] 10. The significance of this invention lies in changing the difficult problem of treating high-salt, high-calcium and high-magnesium wastewater and waste salt in my country, making it a new system and method with economic efficiency, and with outstanding economic and social benefits.

[0080] 11. Another technical innovation of this invention is that the pyrolysis process of mixed salt adopts a rotary electromagnetic heating kiln and performs high-temperature salt waste heat recovery. Its advantages are that compared with the gas pyrolysis process, the exhaust gas emission is small, the pollutant emission is small, the disposal is simple, and the investment is low. At the same time, the waste salt after carbonization is recovered into the system through the waste heat recovery unit, and the heat energy recovery efficiency is higher than 50%. Therefore, compared with the existing mixed salt pyrolysis and carbonization processes, its energy saving effect is significant, energy waste is low, the utilization efficiency is high, and the pollutant emission is very small. Attached Figure Description

[0081] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0082] Figure 1 This is a schematic diagram of a system and method for treating high-salt, high-calcium, and high-magnesium wastewater and miscellaneous salts provided in an embodiment of the present invention. Detailed Implementation

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0084] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0085] Example 1

[0086] Taking power plant dewatering wastewater as an example, its water quality is as follows:

[0087] Serial Number name unit numerical values 1 Na+ mg / L 7890 2 Ca2+ mg / L 595 3 Mg2+ mg / L 682 4 Cl- mg / L 8690 5 SO42- mg / L 10600 6 HCO3- mg / L 69 8 Fe mg / L 0.09 9 Ba mg / L 0.11 10 Sr mg / L 3.49 11 F mg / L 27.5 12 pH 6.65 13 TDS mg / L 30600 14 COD mg / L 630 15 BOD mg / L 208 16 TOC mg / L 146

[0088] Take 2 tons of desulfurization wastewater, first add coagulant and heavy metal chelating agent, let it stand in the sedimentation tank for 10 hours, take 1 ton of supernatant from the clarification tank, add excess hydrogen peroxide to the tank, and continuously introduce ozone. After a reaction time of 30 minutes, test the COD value of the wastewater, showing that the COD is 168 mg / L. Continuously aerate the oxidized supernatant for 30 minutes to dilute and decompose the residual hydrogen peroxide and ozone. Add hydrochloric acid to adjust the pH value to 6.5, and pump the supernatant into the activated carbon adsorption tank. The activated carbon tank contains a mixture of granular and powdered carbon, and there is a gas inlet at the bottom of the activated carbon tank. During the 30-minute adsorption, start the bottom of the tank. A blower generates strong gas, agitating the activated carbon inside the tank for 5 minutes. After 30 minutes of static adsorption, the bottom valve of the activated carbon is opened, and brine slowly enters the clear water tank. After being pumped through multi-media filtration and ultrafiltration membrane filtration, the SS (suspended solids) content in the water is tested at 3.5 ppm. The ultrafiltration permeate enters the ultrafiltration clear water tank, where the COD value is tested at 34 mg / L. The calcium ion content in the solution is 580 mg / L, and the magnesium ion content is 670 mg / L. The prepared composite scale inhibitor and the clear water are then added to the reagent mixing tank and rapidly stirred. The solution is then pumped into the nanofiltration unit for observation of solution changes. Adjust the circulation pump. When the nanofiltration concentrate reaches approximately 200 kg, the concentrate enters the concentrate tank. Add 0.3 kg of calcium sulfate crystals, 1 kg of lime slurry, and 1 g of inhibition-breaking agent to the concentrate tank. Continuously stir at a speed of 5 rpm for 60 minutes, then stop. At this point, the solution is in a turbid state with suspended solids. Pump the slurry into the clarifying tank, add 4 g each of polyacrylamide and polyferrous sulfate, and let it stand for 2 hours. The solution separates into layers, with gypsum slurry at the bottom. Filter the solution through a filter with a filter precision of 5 microns. Transfer the slurry to the slurry tank and maintain a sedimentation state for 1 hour. Take 2000 liters of the solution. 90 grams of anhydrous calcium chloride was divided into two portions of 45 grams each. First, 45 grams of calcium chloride were added to a 2000-liter solution, stirred, and allowed to stand for one hour. Then, the solution was filtered. The second 45 grams of calcium chloride were added, stirred, and allowed to stand for one hour. At this point, the sulfate concentration in the solution was 843 μM / L. The supernatant was then deeply filtered, and the 2000-liter solution was divided into two portions. One portion was treated with excess ammonium carbonate. After standing, white suspended matter was observed and filtered, confirming it to be calcium carbonate. The other portion of the solution was heated and evaporated, and the reaction was observed. When sodium chloride crystals appeared at the bottom and suspended matter appeared on the surface, evaporation was stopped and crystallization was observed. The suspended matter was identified as gypsum.

[0089] Example 2

[0090] Taking the ammonia stripping waste liquid from the ammonia-soda process as an example, the components of the ammonia-soda waste liquid are as follows:

[0091]

[0092] Take 2 liters of ammonia-soda waste liquid, test the COD (2300 ppm), and pass it into an ozone catalytic device for oxidation for 15 minutes. Then, add excess powdered activated carbon to the solution, stir continuously for 2 minutes, and let it stand for 30 minutes. Filter the solution under vacuum five times using the same high-precision multi-layer filter paper. Take 1 liter of the ammonia-soda waste liquid and adjust the pH to approximately 6.5 with sulfuric acid.

[0093] Take 1 kg of zero-emission evaporation crystallization mixture. After testing, the organic matter content is about 2.4 g, sodium sulfate about 560 g, sodium chloride about 420 g, and other miscellaneous salts about 17.6 g. First, heat the waste salt in a resistance heating furnace at a temperature of 500-800℃. After heating for 15 minutes, the salt will clump together. Stop heating and grind it into powder. Continue heating the powder for 15 minutes until the salt turns white. Grind the pyrolysis salt into powder and then take 300 g of decarbonized miscellaneous salt.

[0094] Take 284 grams of pyrolysis-derived mixed salts and divide them into two equal portions of 142 grams of anhydrous sodium sulfate. Add one portion to 1 liter of ammonia-soda waste liquid, add 0.3 liters of deionized water, stir continuously for 10 minutes, add a high-efficiency settling agent, let it stand for 60 minutes to settle, filter, and vacuum filter once. Add the other 142 grams of pyrolysis-derived mixed salts to the clear liquid, stir for 10 minutes, add a high-efficiency settling agent, let it stand for 60 minutes to settle, filter, and vacuum filter. Repeat the stirring of the solids obtained from the two reactions in 1 liter of deionized water, vacuum filter, and the solid is determined to be gypsum. Dry at 300℃, and the obtained product is white dehydrated calcium sulfate with a purity of 99.3% and a chloride ion content of 0.03%.

[0095] The resulting solution was evaporated and crystallized at 70℃. As evaporation proceeded, the solution became cloudy. Evaporation was stopped when half the solution had evaporated, and the solution was cooled, filtered, and then evaporated again. At this point, suspended matter reappeared in the solution. When sodium chloride crystals appeared at the bottom of the container, these crystals were removed, dried, and the purity was tested to be 98.3%.

[0096] Example 3

[0097] The mother liquor from evaporation and crystallization was mixed with calcium hydroxide slurry and ammonium chloride slurry and continuously stirred in a 2L stirred reactor. The reaction concentrations of the mother liquor, ammonium chloride, and calcium hydroxide were 20g / 100g slurry, 30g / 100g slurry, and 18g / 100g slurry, respectively. The stirring reaction temperature was 22℃±1℃, and the residence time was 5min. At this time, the solution began to react, and calcium chloride crystals formed. The stirred reactor was continuously heated, and ammonia and vapors were continuously released. After condensation through a condenser, the condensate became liquid and was identified as ammonia water. The concentrated slurry was filtered to obtain mother liquor and filter cake. The mother liquor was evaporated and dried, and the filter cake was cooled to form block crystals. It was continuously heated and dried at 350℃, gradually turning white and forming solid mixed salt substances. The main components were calcium sulfate and calcium chloride. The components of the dried mother liquor were calcium chloride, calcium sulfate, nitrates, potassium salts, etc.

[0098] Through the specific embodiments described above, those skilled in the art can easily implement the present invention. However, it should be understood that the present invention is not limited to the specific embodiments described above. Based on the disclosed embodiments, those skilled in the art can arbitrarily combine different technical features to achieve different technical solutions.

Claims

1. A treatment system for high-salt, high-calcium-magnesium wastewater and miscellaneous salts, characterized in that, include: Oxidation unit, activated carbon adsorption unit, equalization tank 1, sand filtration unit, ultrafiltration unit 1, reagent mixing unit, nanofiltration unit 1, equalization tank 2, clarification tank 1, softening reaction tank, clarification tank 2, media filtration tank, ultrafiltration unit 2, nanofiltration unit 2, carbonizer, cooler, mother liquor ammonia removal unit, slurry dewatering, drying, miscellaneous salt deheating, waste heat recovery, reaction tank, clarification tank 3, evaporation crystallization unit, alkali production unit, ammonia recovery unit, buffer tank, concentration unit 1, concentration unit 2, deep desilication unit, gypsum deposition tank, gypsum cleaning unit, plate and frame filter press 1, plate and frame filter press 2; The high-salt, high-calcium, and high-magnesium wastewater enters the inlet of the oxidation unit, the outlet of the oxidation unit is connected to the inlet of the activated carbon adsorption unit, the outlet of the activated carbon adsorption unit is connected to the first inlet of the equalization tank 1, the outlet of the equalization tank 1 is connected to the inlet of the sand filter unit, and a second inlet for adding reagents is left at the top of the equalization tank 1. The outlet of the sand filter unit is connected to the inlet of the ultrafiltration unit 1, the outlet of the ultrafiltration unit 1 is connected to the first inlet of the reagent mixing unit, the second inlet of the reagent mixing unit is the reagent addition port, the outlet of the reagent mixing unit is connected to the inlet of the nanofiltration unit 1, the first outlet of the nanofiltration unit 1 is connected to the first inlet of the equalization tank 2, and the second outlet of the nanofiltration unit 1 is connected to the inlet of the deep desilication unit. The second inlet of the equalization tank 2 is connected to the second outlet of the gypsum deposition unit, the third inlet of the equalization tank 2 is a reagent addition port, the outlet of the equalization tank 2 is connected to the first inlet of the clarification tank 1, the fourth inlet of the equalization tank 2 is connected to the second outlet of the clarification tank 1, the second inlet of the clarification tank 1 is a reagent addition port, and the first outlet of the clarification tank 1 is connected to the first inlet of the softening reaction tank. The second inlet of the softening reaction tank is connected to the outlet of the carbonizer, the outlet of the softening reaction tank is connected to the inlet of the clarification tank 2, the first outlet of the clarification tank 2 is connected to the inlet of the media filter tank, and the second outlet of the clarification tank 2 is the calcium carbonate outlet. The outlet of the media filtration tank is connected to the inlet of the ultrafiltration unit 2, the outlet of the ultrafiltration unit 2 is connected to the inlet of the nanofiltration unit 2, the first outlet of the nanofiltration unit 2 is connected to the first inlet of the reaction tank, and the second outlet of the nanofiltration unit 2 is connected to the second inlet of the concentration unit 2. The mixed salt enters the mixed salt pyrolysis inlet, the mixed salt pyrolysis outlet is connected to the waste heat recovery inlet, and the waste heat recovery outlet is connected to the second inlet of the reaction tank. The outlet of the reaction tank is connected to the inlet of the clarifier 3, and the third inlet of the reaction tank is connected to the second outlet of the ammonia recovery unit. The first outlet of the clarification tank 3 is connected to the inlet of the evaporation and crystallization unit, and the second outlet is connected to the first inlet of the gypsum deposition tank. The first outlet of the evaporation crystallization unit is connected to the third inlet of the alkali production unit, the second outlet of the evaporation crystallization unit outputs sodium chloride, the third outlet is connected to the third inlet of the mother liquor deammoniation unit, and the fourth outlet is connected to the second inlet of the gypsum sedimentation tank. The first outlet of the alkali production unit is connected to the second inlet of the ammonia recovery unit, and the second outlet of the alkali production unit outputs sodium carbonate or sodium bicarbonate. The first inlet of the alkali production unit is connected together with the first outlet of the ammonia recovery unit and the outlet of the buffer tank; Calcium oxide or calcium carbide waste residue is introduced into the first inlet of the ammonia recovery unit. The first outlet of the deep desilication unit discharges desilication impurities, the second outlet is connected to the inlet of concentration unit 1, the outlet of concentration unit 1 is connected to the inlet of concentration unit 2, the outlet of concentration unit 2 is connected to the inlet of the buffer tank, the third inlet of concentration unit 2 is the inlet of steam or high-temperature hot water, and concentration unit 2 has a second outlet for condensate. The first outlet of the gypsum sedimentation tank is connected to the inlet of plate and frame filter press 1, the first outlet of plate and frame filter press 1 is connected to the inlet of gypsum cleaning unit, the first outlet of gypsum cleaning unit is connected to the inlet of plate and frame filter press 2, the second outlet of gypsum cleaning unit outputs cleaning liquid, the first outlet of plate and frame filter press 2 outputs gypsum, and the second outlet outputs filter clear liquid. CO2 and ammonia water enter the first inlet of the carbonizer, the second inlet of the carbonizer is connected to the outlet of the cooler, and the inlet of the cooler is connected to the first outlet of the mother liquor deammoniation unit. The mother liquor deammoniation unit has calcium oxide introduced through its first inlet, steam introduced through its second inlet, and its second outlet connected to the slurry dewatering inlet. The slurry dewatering outlet is connected to the drying inlet.

2. The treatment system for high-salt, high-calcium, and high-magnesium wastewater and miscellaneous salts according to claim 1, characterized in that, The carbonizer consists of a tower-type carbonization tower or a tank-type carbonization tank and a neutralization tank for ammonia water and carbonization slurry.

3. The treatment system for high-salt, high-calcium, and high-magnesium wastewater and miscellaneous salts according to claim 1, characterized in that, The gypsum cleaning unit consists of a slurry suspension cleaning tank and a slurry crystallization tank.

4. The treatment system for high-salt, high-calcium, and high-magnesium wastewater and miscellaneous salts according to claim 1, characterized in that, The pharmaceutical mixing unit is a rapid pipeline mixer, with a high-frequency acoustic oscillator welded to the outer wall of the pipeline.

5. The treatment system for high-salt, high-calcium, and high-magnesium wastewater and miscellaneous salts according to claim 1, characterized in that, The alkali production unit uses traditional ammonia-soda process or combined alkali process system equipment.

6. The treatment system for high-salt, high-calcium, and high-magnesium wastewater and miscellaneous salts according to claim 1, characterized in that, The concentrated liquid from the nanofiltration unit 1 enters the equalization tank 2, which is a structure consisting of multiple parallel or series-connected stirred tanks equipped with a stirrer.

7. The treatment system for high-salt, high-calcium-magnesium wastewater and miscellaneous salts according to claim 1, characterized in that, The pyrolysis of mixed salts uses an electromagnetic rotary kiln heater, and the waste heat recovery uses a rotary drum waste heat recovery unit.

8. The treatment system for high-salt, high-calcium, and high-magnesium wastewater and miscellaneous salts according to claim 1, characterized in that, The slurry dehydration is carried out using a steam-heated negative pressure vacuum evaporator, and the drying is carried out using one of the following: a drum dryer, a paddle agitator, or a disc dryer.

9. The treatment system for high-salt, high-calcium, and high-magnesium wastewater and miscellaneous salts according to claim 1, characterized in that, The nanofiltration unit 1 and nanofiltration unit 2 adopt one or a combination of two types of antifouling spiral wound nanofiltration membranes or high-pressure disc antifouling nanofiltration membranes.

10. A method for treating high-salt, high-calcium, and magnesium wastewater and miscellaneous salts using the treatment system for high-salt, high-calcium, and magnesium wastewater and miscellaneous salts as described in claim 1, characterized in that, The high-salt, high-calcium, and high-magnesium wastewater refers to high-salt, high-calcium, and high-magnesium concentrated water that has been concentrated through at least two consecutive reverse osmosis membranes, or one or more of the following mixed waters after filtration and purification: desulfurization wastewater, concentrated brine from nanofiltration, industrial acid-base neutralization wastewater, evaporation-concentrated mixed salt wastewater, evaporation-concentrated mother liquor, and high-mineralization mine water. The soluble salt content of the high-salt, high-calcium, and high-magnesium wastewater is not less than 10,000 mg / L. The oxidation unit employs one or more combinations of ozone catalytic oxidation, Fenton oxidation, electrochemical oxidation, sodium hypochlorite oxidation, and hydrogen peroxide oxidation, with an oxidation removal rate of not less than 50%. The activated carbon adsorption unit uses granular activated carbon or powdered activated carbon, and the organic matter removal rate of the high-salt, high-calcium and high-magnesium wastewater after activated carbon adsorption is not less than 70%. The pH of the equalization tank 1 is adjusted to 6.5 by adding either hydrochloric acid or sulfuric acid. After being filtered and purified by sand filter unit 1 and ultrafiltration unit 1, the SS in the effluent is less than 3ppm. The agent added in the agent mixing unit is an organic chelating agent, which includes three or more of the following: aminotrimethylene phosphonic acid (ATMP), hydroxyethylidene diphosphonic acid (HEDP), polystyrene sulfonate, copolymer of sulfonic acid and acrylic acid, aminopropanesulfonic acid-acrylic acid copolymer, and polyacrylic acid-2-acrylamide methylpropanesulfonic acid group, and the concentration of the compound scale inhibitor added is 5 to 15 ppm. The water production efficiency of the nanofiltration unit 1 is not less than 65%; In equalization tank 2, a coagulation and sedimentation reaction is carried out by adding lime slurry, scale inhibitor deactivator, and coagulant. The scale inhibitor deactivator refers to Fe... 3+ Compounds, Al 3+ One or two combinations of compounds are added at a rate of 10–30 ppm, and the wastewater retention time in equalization tank 2 is 1.5 hours. When the pH of the wastewater in equalization tank 2 is ≥10, the scale inhibitor loses its chelating effect on calcium ions. After the solubilization effect of the agent fails, supersaturated calcium sulfate precipitates out, forming gypsum solid suspension. The slurry containing calcium sulfate solid in equalization tank 2 enters clarification tank 1. The wastewater retention time in clarifier 1 shall not be less than 1 hour, and the flow rate of the slurry at the bottom of clarifier 1 returned to equalization tank 2 shall not be less than 0.1% of the wastewater flow rate entering clarifier 1; The supernatant from clarifier 1 enters the softening reaction tank, which is then fed with a thick ammonium carbonate slurry produced by the carbonizer. The following reactions occur: (NH4)2CO3+CaCl2=2NH4Cl+CaCO3↓ CaSO4+2NH3+CO2+H2O=(NH4)2SO4+CaCO3↓; After the softening reaction, the wastewater enters the clarification tank 2, and the clarification time is not less than 1 hour. The clear liquid enters the media filter tank, which refers to either a sand filter or a multi-media filter. After filtration in the media filter tank, the wastewater enters the ultrafiltration unit 2, where it undergoes deep filtration, and the SS in the effluent is less than 3ppm. The water production rate of nanofiltration unit 2 is not less than 50%, and the separated water is a monovalent sodium chloride solution that enters concentration unit 2. The concentrated water from nanofiltration unit 2 enters the reaction tank, and the reaction time in the reaction tank is not less than 2 hours. The reaction tank consists of two or more tanks connected in series. A stirred reaction occurs within the reaction tank. The sodium sulfate in the reaction tank originates from pyrolysis and waste heat recovery of miscellaneous salts. It reacts with calcium chloride slurry or a mixed salt solution of calcium chloride and sodium chloride from the ammonia recovery unit. The reaction within the reaction tank is as follows: Na2SO4+CaCl2=CaSO4↓+2NaCl; The slurry from the reaction tank enters the clarifier 3, where the retention time is no less than 1 hour. The supernatant from clarifier 3 enters the evaporation crystallization unit, which is one or two of the multi-effect evaporation crystallization or MVR evaporation crystallization combined in series. The evaporation temperature is between 65 and 95°C. The evaporation crystallization adopts the gypsum seed crystal method for salt separation crystallization. The heater and heat exchanger adopt three-phase flow heat exchange anti-scaling technology. Evaporation and crystallization produce gypsum, sodium chloride, and mother liquor, with a portion of the sodium chloride entering the alkali production unit. The ammonium chloride-containing mother liquor or ammonium chloride slurry produced by the alkali production unit enters the ammonia recovery unit, which adopts one of the following methods: steam stripping ammonia or thermal evaporation and concentration for ammonia extraction. The waste liquid after ammonia recovery is either ammonia-soda waste liquid or calcium chloride waste liquid, which enters the reaction tank for reaction. The ammonia-water or gaseous ammonia mixture from the ammonia recovery unit is returned to the alkali production unit. The gypsum sedimentation tank receives gypsum slurry from the equalization tank 2, gypsum slurry separated by evaporation and crystallization, and gypsum slurry after reaction in the clarification tank 3. After sedimentation, it enters the plate and frame filter press 1, is dewatered by the plate and frame filter press, and enters the gypsum cleaning unit. After cleaning, the gypsum slurry enters the plate and frame filter press 2 for dewatering to a moisture content of less than 50%. The water produced by nanofiltration unit 1 enters the deep desilication unit, where desilication is carried out by one or more combinations of chemical desilication, resin adsorption, or electrochemical coagulation. After desilication, the sodium chloride solution enters concentration unit 1, which employs one or a combination of reverse osmosis concentration or electrodialysis concentration devices. After concentration, the sodium chloride solution enters concentration unit 2, which uses a low-temperature residual heat method for evaporation and concentration, and the pH value of the solution is below 7. After the concentrated salt solution from concentration unit 2 enters the buffer tank, it enters the alkali production unit. The mother liquor from evaporation and crystallization contains ammonia ions, a small amount of sulfate ions, chloride ions, and nitrates, and enters the mother liquor deammoniation unit; The mother liquor deammoniation unit uses steam stripping or evaporation for deammoniation, and the alkaline additive is quicklime. After being cooled, the deammoniated ammonia gas enters the carbonizer to form ammonia water. The carbonizer is a tower-type or tank-type structure, and the following reaction occurs: 2NH3·H2O+CO2=(NH4)2CO3+H2O; The mother liquor after ammonia extraction enters the slurry dewatering unit for further drying and distribution.

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