A method and system for treating incineration fly ash and flue gas by crystallization and granulation

Abstract

The present invention provides a method and system for treating incineration fly ash and flue gas by nuclear crystallization granulation, which belongs to the technical field of incineration waste treatment. The treatment method comprises the following steps: removing solid particles from the incineration flue gas and enriching CO2 in the incineration flue gas to obtain CO2-rich waste gas; leaching metal ions from the incineration fly ash with an amphoteric electrolyte solution, separating the solid and the liquid, and obtaining a leachate containing metal ions and purified fly ash; in the presence of nuclear crystallization granulation seeds, passing the CO2-rich waste gas into the leachate for reaction to obtain carbonate granulation, regenerated amphoteric electrolyte solution and tail gas. The treatment method and system provided by the present invention are based on nuclear crystallization granulation technology, and can simultaneously achieve the mineralization and fixation of CO2 in the incineration flue gas and the removal and granulation recovery of metal ions in the incineration fly ash, as well as the metal dissolution-mineralization cycle.

Description

Technical Field

[0001] The invention belongs to the technical field of incineration waste treatment, and in particular relates to a nucleation granulation treatment method and treatment system for incineration fly ash and flue gas. Background Art

[0002] Waste incineration is widely used as an effective method for waste reduction and resource utilization. However, the fly ash generated during waste incineration has become a pressing issue. Fly ash not only contains a large amount of heavy metals and hazardous substances, which, if discharged without treatment, can have serious environmental impacts, but it is also rich in various trace elements and minerals, offering potential for utilization.

[0003] In the existing waste incineration fly ash treatment technology, although there are some methods for treating heavy metals and harmful substances in fly ash, there are still some shortcomings. First, the potential hazards of water-soluble salts have not been eliminated and have not been effectively utilized, which not only wastes resources but also may cause secondary pollution to the environment. Secondly, heavy metal pollution still exists, and secondary fly ash still needs to be landfilled. On the one hand, a large amount of landfill space still needs to be reserved, which increases the treatment cost. On the other hand, it may cause long-term pollution to the soil and groundwater. In addition, the incomplete incineration of highly toxic and carcinogenic substances such as dioxins is also a serious problem in the current fly ash treatment. If these harmful substances are directly discharged without effective treatment, they will pose a serious threat to human health and the ecological environment.

[0004] In addition, the flue gas produced by garbage incineration contains a large amount of carbon dioxide, which is directly emitted into the atmosphere and will cause global warming. Traditional carbon sequestration technologies mostly rely on natural carbon sinks, such as forests and oceans, but the carbon sequestration capacity of these natural carbon sinks is limited and affected by various factors. Carbon dioxide mineralization technology converts carbon dioxide into stable carbonate minerals through chemical reactions, thereby achieving long-term and stable carbon sequestration. However, most current carbon dioxide mineralization technologies have problems such as high cost and low efficiency, which limit their widespread application.

[0005] Therefore, in order to solve the challenges in waste incineration treatment, it is urgent to develop an efficient and environmentally friendly technology to simultaneously remove heavy metals from fly ash and carbon dioxide from incineration flue gas. Summary of the Invention

[0006] In response to the shortcomings of the prior art, the present invention aims to provide a method and system for treating incineration fly ash and flue gas through nucleation granulation. The treatment method and system provided by the present invention are based on nucleation granulation technology and can simultaneously achieve the mineralization and fixation of CO2 in incineration flue gas and the removal and granulation recovery of metal ions in incineration fly ash, thereby achieving the reduction, harmlessness, and resource utilization of incineration waste. Furthermore, the amphoteric electrolyte solution used in the method provided by the present invention can be regenerated during the nucleation granulation process, achieving an effective metal dissolution-mineralization cycle during the incineration fly ash treatment process, further enhancing the sustainability and environmental friendliness of the method.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for treating incineration fly ash and flue gas by nucleation and granulation, the method comprising the following steps:

[0009] Remove solid particles from the incineration flue gas and enrich the CO2 in the incineration flue gas to obtain CO2-rich waste gas;

[0010] Leaching the metal ions in the incineration fly ash with an amphoteric electrolyte solution, separating the solid and the liquid to obtain a leachate containing metal ions and purified fly ash;

[0011] In the presence of nucleation granulation seeds, the CO2-rich waste gas is introduced into the leaching solution to react, thereby obtaining carbonate granules, regenerated amphoteric electrolyte solution and tail gas.

[0012] The treatment method provided by the present invention is based on the nuclear crystal granulation technology, which can simultaneously achieve the mineralization and fixation of CO2 in the incineration flue gas and the removal and granulation recovery of metal ions in the incineration fly ash. Specifically, the functions of each step are as follows:

[0013] CO2 Enrichment: Since the CO2 concentration in waste incineration flue gas is low, typically in the 10-15% range, direct treatment is both inefficient and costly. Therefore, capturing and enriching this low-concentration CO2 through a CO2 enrichment device is particularly important. This step is a crucial link in the entire incineration flue gas treatment process, not only affecting the efficient utilization of resources but also directly impacting environmental protection and the company's economic benefits.

[0014] Metal ion leaching: The present invention selects an amphoteric electrolyte solution as a leaching agent because it has good buffering properties and mass transfer efficiency. On the one hand, the amphoteric electrolyte can form a complex with the metal ions. At the same time, the amphoteric electrolyte solution can effectively adjust the pH value of the solution, promote the dissolution of the metal ions, and serve as a pH buffer system to ensure the stability of the leaching process. On the other hand, during the nucleation granulation process, the amphoteric electrolyte acts as a proton donor and can combine with the CO2 molecules to form zwitterions. Therefore, it has a higher CO2 absorption capacity and a faster absorption rate, which can significantly improve the efficiency of CO2 in gas-liquid two-phase mass transfer and liquid phase mass transfer, and increase the liquid phase CO2 saturation concentration. In addition, in this process, soluble salts, alkalis, etc. in the fly ash can also be effectively removed, reducing the volume of the fly ash and making the fly ash more convenient for subsequent transportation, storage and processing.

[0015] Nucleation Granulation: The present invention utilizes nucleation granulation seeds to further promote CO2 hydrolysis to produce carbonate ions, lowering the nucleation barrier of metal ions and inducing the metal ions in the leachate to crystallize as carbonate precipitates on the surface of the nucleation granulation seeds, forming carbonate granules. Simultaneously, during this process, the complex between the zwitterions and metal ions in the amphoteric electrolyte solution is broken. The zwitterions can then accept hydrogen ions (from CO2 hydrolysis) to regenerate into an amphoteric electrolyte solution, which can then be used again to leach metal ions from incineration fly ash, thus completing the metal dissolution-mineralization cycle.

[0016] The tail gas generated by the treatment method provided by the present invention can be directly discharged into the atmosphere after meeting emission standards. The purified fly ash can be used as building materials, soil conditioners, etc., and the carbonate granules can be used as cement clinker raw materials. This not only achieves the treatment of incineration fly ash and flue gas, but also realizes the reuse of waste, with significant economic and environmental benefits.

[0017] In some embodiments of the present invention, the removal of solid particles from the incineration flue gas is performed using a particle filter.

[0018] In some embodiments of the present invention, the enrichment of CO2 in the incineration flue gas is carried out using a carbon dioxide enrichment device.

[0019] In some embodiments of the present invention, the carbon dioxide enrichment device comprises one or more of a pressure swing adsorption device and a temperature swing adsorption device. Pressure swing and temperature swing adsorption technologies can effectively enrich low-concentration carbon dioxide to a higher concentration (approximately 35-45%) through selective adsorption and desorption of adsorbents, thereby significantly improving the utilization rate of carbon dioxide and the potential for subsequent resource recovery.

[0020] In some embodiments of the present invention, the volume content of CO2 in the CO2-rich exhaust gas is 35-45%, for example, 35%, 36%, 38%, 40%, 42%, 43%, or 45%. However, the present invention is not limited to the values ​​listed, and other values ​​not listed within the range are also applicable.

[0021] In some embodiments of the present invention, the step of leaching the metal ions in the incineration fly ash comprises: mixing the ampholyte solution with the incineration fly ash and stirring.

[0022] In some embodiments of the present invention, the stirring speed is 300-600 rpm; for example, it can be 300 rpm, 320 rpm, 350 rpm, 380 rpm, 400 rpm, 420 rpm, 450 rpm, 480 rpm, 500 rpm, 520 rpm, 550 rpm, 580 rpm or 600 rpm, etc. However, the present invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0023] In some embodiments of the present invention, the stirring time is 0.5-2 hours, for example, 0.5 hours, 0.8 hours, 1 hour, 1.2 hours, 1.5 hours, 1.8 hours or 2 hours, etc. However, the present invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0024] Controlling the stirring speed and time within the above ranges is helpful to fully leaching the metal ions in the incineration fly ash.

[0025] In some embodiments of the present invention, the mass volume ratio of the incineration fly ash to the ampholyte solution is 200-300 g / L; for example, it can be 200 g / L, 210 g / L, 220 g / L, 230 g / L, 240 g / L, 250 g / L, 260 g / L, 270 g / L, 280 g / L, 290 g / L, or 300 g / L. However, the present invention is not limited to the values ​​listed above, and other values ​​not listed within this range are also applicable.

[0026] In the present invention, if the ratio of incineration fly ash to amphoteric electrolyte solution is too large, it may lead to insufficient leaching of metal ions in the incineration fly ash; if the ratio of incineration fly ash to amphoteric electrolyte solution is too small, the concentration of metal ions in the leachate will be low, and the treatment efficiency of the nucleation granulation stage will be reduced.

[0027] In some embodiments of the present invention, the concentration of the ampholyte solution is 0.5-1.2 mol / L; for example, it can be 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, or 1.2 mol / L. However, the present invention is not limited to the values ​​listed above, and other values ​​not listed within this range are also applicable.

[0028] In the present invention, maintaining the concentration of the ampholyte solution within the above range helps ensure good metal ion leaching efficiency and CO2 mass transfer efficiency. If the concentration of the ampholyte solution is too low, the metal ion leaching efficiency and CO2 mass transfer efficiency are low, and the treatment efficiency of incineration fly ash and flue gas is reduced. Further increasing the concentration of the ampholyte solution is unnecessary and will also increase costs.

[0029] In some embodiments of the present invention, the ampholyte comprises amino acids, including but not limited to alanine, sarcosine, cysteine, serine, histidine, glycine, and the like.

[0030] In the present invention, the metal ions include metal ions that can react with carbonate to form carbonate precipitates, including but not limited to one or more of calcium ions, magnesium ions, zinc ions, copper ions and lead ions.

[0031] In some embodiments of the present invention, the solid-liquid separation is performed using a centrifugal dehydrator. Solid-liquid separation is an essential step in the incineration fly ash treatment process, its purpose being to separate the leachate from the fly ash for subsequent processing. Centrifugal dehydrators are the preferred equipment for solid-liquid separation due to their high separation capacity and ease of operation.

[0032] In some embodiments of the present invention, the centrifugal dehydrator has a centrifugal speed of 5000-8000 rpm, for example, 5000 rpm, 5500 rpm, 6000 rpm, 6500 rpm, 7000 rpm, 7500 rpm, or 8000 rpm; and the centrifugal time is 5-10 min, for example, 5 min, 6 min, 7 min, 8 min, 9 min, or 10 min. However, the present invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0033] In some embodiments of the present invention, the nucleation granulation seed comprises a support material and alkaline active sites supported on the support material; the material of the alkaline active sites comprises one or more of alkali metal oxides and alkaline earth metal oxides.

[0034] In some embodiments of the present invention, the alkali metal oxide includes one or more of Na2O, K2O and Rb2O, and the alkaline earth metal oxide includes CaO.

[0035] In some embodiments of the present invention, the support material includes one or more of alumina, molecular sieves, zeolites, activated carbon and mesoporous silica.

[0036] In the present invention, the method for preparing the nucleation granulation seed comprises the following steps:

[0037] (1) mixing a support material with a solution of an alkaline active site precursor to load the alkaline active site precursor on the support material, and drying to obtain a support material loaded with the alkaline active site precursor;

[0038] (2) calcining the carrier material loaded with the alkaline active site precursor in a protective atmosphere to decompose the alkaline active site precursor to form alkaline active sites, thereby obtaining the seed crystal.

[0039] In some embodiments of the present invention, the alkaline active site precursor is one or more of a hydroxide of a metal element in the alkaline active site, a strong acid and strong base salt, and preferably a nitrate of a metal element in the alkaline active site.

[0040] As a non-limiting example, the basic active site precursor in the present invention may include one or more of potassium nitrate, potassium fluoride, potassium hydroxide, sodium nitrate, calcium nitrate, and rubidium nitrate.

[0041] In some embodiments of the present invention, the ratio of the molar amount of the metal element in the solution of the alkaline active site precursor to the mass of the support material is 0.25-1.7 mmol / g.

[0042] In some embodiments of the present invention, the concentration of the metal element in the solution of the alkaline active site precursor is 0.1-0.5 mol / L.

[0043] In some embodiments of the present invention, the mass volume ratio of the support material to the solution of the alkaline active site precursor is 300-400 g / L.

[0044] In some embodiments of the present invention, the mixing in step (1) is performed under stirring conditions.

[0045] In some embodiments of the present invention, the mixing temperature in step (1) is 40-50°C.

[0046] In some embodiments of the present invention, the mixing time in step (1) is 3-5 hours.

[0047] In some embodiments of the present invention, the drying temperature in step (1) is 60-80°C.

[0048] In some embodiments of the present invention, the drying time in step (1) is 24-36 hours.

[0049] As a non-limiting example in the present invention, the calcination temperature in step (2) is 600-800°C.

[0050] As a non-limiting example of the present invention, the calcination time in step (2) is 2-4 hours.

[0051] In some embodiments of the present invention, the heating rate of the calcination in step (2) is 5-8°C / min.

[0052] In some embodiments of the present invention, the method for preparing the core crystal granulation seed further comprises the following steps: before the mixing in step (1), the carrier material is sequentially ground, sieved with a 60-80 mesh sieve, washed and dried.

[0053] In some embodiments of the present invention, the method for preparing the core crystal granulation seed further comprises the following steps: cooling and screening the seed crystals after the calcination in step (2) to remove possible impurities and particles that do not meet the requirements, thereby ensuring that the size and performance of the seed crystals meet the requirements.

[0054] In the present invention, there is no special restriction on the specific reaction conditions in the nucleation granulation process, such as ventilation flow rate, water inlet flow rate, hydraulic retention time (reaction time), etc. Those skilled in the art can adjust them according to the actual wastewater quality and treatment efficiency to ensure that the metal ions and CO2 fully react to form carbonate precipitates.

[0055] As a non-limiting example, the ratio of the volume of CO2 in the CO2-rich waste gas to the molar amount of metal ions in the leachate is 0.28-0.4 L / mol; for example, it can be 0.28 L / mol, 0.3 L / mol, 0.32 L / mol, 0.35 L / mol, 0.38 L / mol or 0.4 L / mol, etc.

[0056] As a non-limiting example, the reaction time is more than 10 minutes, for example, 10 minutes, 12 minutes, 15 minutes, 18 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc. However, the present invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0057] In some embodiments of the present invention, the step of forming carbonate granules is performed in a nucleation granulation reactor.

[0058] When reacting in the nucleus crystal granulation reactor, carbonate precipitates crystallize on the surface of the nucleus crystal granulation seed and gradually grows. Under the high-intensity volume extrusion, it shrinks and dehydrates to form a dense carbonate granulation body that is almost free of water.

[0059] In some embodiments of the present invention, the treatment method further comprises: circulating the regenerated ampholyte solution for leaching metal ions in the incineration fly ash.

[0060] In some embodiments of the present invention, the treatment method further comprises: drying the purified fly ash.

[0061] In some embodiments of the present invention, the treatment method further includes: detecting the CO2 content in the tail gas, and discharging the CO2 when the CO2 content reaches the emission standard; when the CO2 content does not reach the emission standard, returning the tail gas to react with the leachate.

[0062] In a second aspect, the present invention provides a system for processing fly ash and flue gas by crystallization and granulation, the system comprising:

[0063] Particle filter, used to remove solid particles from incineration flue gas;

[0064] a carbon dioxide enrichment device, the inlet of which is connected to the outlet of the particle filter, for enriching CO2 and generating CO2-rich exhaust gas;

[0065] Fly ash cleaning device, used to leach metal ions from incineration fly ash using an ampholyte solution;

[0066] a centrifugal dehydration device, the inlet of which is connected to the outlet of the fly ash washing device, for solid-liquid separation to obtain leachate and purify fly ash; and

[0067] Nucleation granulation reactor;

[0068] The nucleation granulation reactor comprises a reactor body, on which is provided:

[0069] a water inlet for introducing the leachate separated by the centrifugal dehydration device;

[0070] An air inlet, for introducing the CO2-rich waste gas generated by the carbon dioxide enrichment device;

[0071] A water outlet, used to discharge the purified liquid;

[0072] An air outlet for discharging exhaust gas;

[0073] The crystal discharge port is used to discharge the granules generated in the nuclear crystal granulation reactor.

[0074] In some embodiments of the present invention, the water outlet of the core crystallization granulation reactor is connected to the inlet of the fly ash washing device.

[0075] In some embodiments of the present invention, the gas outlet of the core crystal granulation reactor is connected to at least two pipelines, one of which is connected to the gas inlet of the core crystal granulation reactor, and the other pipelines may be connected to the atmosphere.

[0076] In some embodiments of the present invention, the carbon dioxide enrichment device includes one or more of a pressure swing adsorption device and a temperature swing adsorption device.

[0077] In some embodiments of the present invention, the processing system further comprises a CO2 monitoring unit for monitoring the CO2 content in the tail gas discharged from the core crystallization granulation reactor.

[0078] In some embodiments of the present invention, the processing device further includes a drying device for drying the purified fly ash separated by the centrifugal dehydration device.

[0079] Compared with the prior art, the present invention has the following beneficial effects:

[0080] The treatment method and system provided by the present invention can simultaneously achieve the mineralization and fixation of CO2 in incineration flue gas and the removal and granulation recovery of metal ions in incineration fly ash. The resulting tail gas can be directly discharged into the atmosphere after meeting emission standards. The purified fly ash can be used as a building material, soil conditioner, etc., and the carbonate granules can be used as a raw material for cement clinker. This not only achieves the treatment of incineration fly ash and flue gas, but also realizes the reuse of waste, with significant economic and environmental benefits.

[0081] In addition, the treatment method provided by the present invention uses an amphoteric electrolyte solution for leaching metal ions in incineration fly ash, and the amphoteric electrolyte solution is regenerated during the nucleation granulation process, thereby realizing an effective metal dissolution-mineralization cycle during the incineration fly ash treatment process, further enhancing the sustainability and environmental friendliness of the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 This is a process flow chart of a method for treating incineration fly ash and flue gas provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0083] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. It should be understood by those skilled in the art that the specific embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0084] The core crystal granulation seed used in the embodiment of the present invention includes a carrier coconut shell activated carbon and alkaline active sites K2O supported on the carrier coconut shell activated carbon, and the preparation method thereof is as follows:

[0085] Select coconut shell activated carbon with high specific surface area (strength 95%, specific surface area about 950m 2 / g) as a carrier material. First, grinding and sieving were performed to obtain 60-80 mesh coconut shell activated carbon, which was repeatedly washed three times with deionized water and dried in an oven at 80°C for 6 hours to constant weight; 5.06g of KNO3 was dissolved in 200mL of deionized water to prepare a potassium nitrate solution with a concentration of 0.25mol / L; 60g of the pretreated coconut shell activated carbon carrier was added to the above potassium nitrate solution, stirred continuously at 45°C for 4 hours to fully load the potassium nitrate, and then dried in an oven at 70°C for 32 hours to obtain coconut shell activated carbon loaded with potassium nitrate; then placed in a covered crucible, heated to 700°C at a heating rate of 6°C / min under a nitrogen atmosphere, and kept warm for 3 hours; after calcination, naturally cooled, and sieved again to obtain 60-80 mesh nucleus crystal granulation seeds (named FC-ac).

[0086] Example 1

[0087] This embodiment provides a system for treating incineration fly ash and flue gas, the system comprising:

[0088] Particle filter, used to remove solid particles from incineration flue gas;

[0089] a carbon dioxide enrichment device, the inlet of which is connected to the outlet of the particle filter, for enriching CO2 and generating CO2-rich exhaust gas;

[0090] Fly ash cleaning device, used to leach metal ions from incineration fly ash using an ampholyte solution;

[0091] a centrifugal dehydration device, the inlet of which is connected to the outlet of the fly ash washing device, for solid-liquid separation to obtain leachate and purified fly ash;

[0092] a drying device for drying the purified fly ash separated by the centrifugal dehydration device;

[0093] a nucleation granulation reactor; and

[0094] A CO2 monitoring unit for monitoring the CO2 content in the tail gas discharged from the core crystal granulation reactor;

[0095] The nucleation granulation reactor comprises a reactor body, on which is provided:

[0096] a water inlet for introducing the leachate separated by the centrifugal dehydration device;

[0097] An air inlet, for introducing the CO2-rich waste gas generated by the carbon dioxide enrichment device;

[0098] a water outlet connected to the inlet of the fly ash washing device and used to return the regenerated amphoteric electrolyte solution to the fly ash washing device for recycling;

[0099] An air outlet is used to discharge tail gas, and the air outlet is connected to two pipelines, one of which is connected to the air inlet of the nuclear crystal granulation reactor, and the other pipeline leads to the atmosphere;

[0100] The crystal discharge port is used to discharge the granules generated in the nuclear crystal granulation reactor.

[0101] Example 2

[0102] This embodiment provides a method for treating incineration fly ash and flue gas. In this embodiment, the incineration flue gas and fly ash are taken from a small domestic waste incineration plant. The main types of waste include domestic waste (about 90%) and a small amount of industrial waste (about 10%).

[0103] The CO2 concentration in the boiler flue gas at this waste incineration plant is approximately 10%. The flue gas is first passed through a particulate filter to remove solid particles. The filtered flue gas then enters a pressure swing adsorption unit, where pressure fluctuations cause the adsorbent to absorb and release CO2, increasing the CO2 concentration from its original low concentration to approximately 35% by volume.

[0104] The incineration fly ash was mixed with an alanine solution with a concentration of 0.5 mol / L at a ratio of 200 g / L and stirred at 400 rpm for 1 hour to efficiently leach the metal ions in the fly ash. A centrifugal dehydrator was used to centrifuge at 6000 rpm for 8 minutes to achieve solid-liquid separation, and a leachate containing metal ions and purified fly ash were obtained. The purified fly ash was dried using a drying device and then landfilled in a landfill plant. The water quality of the leachate was analyzed using an inductively coupled plasma mass spectrometer, where the main leached metal ions were calcium (Ca 2+ ), magnesium (Mg 2+ ), zinc (Zn 2+ ), copper (Cu 2+ ) and the leaching concentrations were 3500 mg / L, 190 mg / L, 30 mg / L, and 26 mg / L, respectively.

[0105] 50L of leachate and CO2-rich waste gas are introduced into a nuclear crystallization granulation reactor equipped with nuclear crystallization granulation seeds FC-ac, with the seed filling height being 25% of the effective height of the reactor (the effective height being the height from the water inlet to the water outlet), the water inlet flow rate being 20L / h, the air inlet flow rate being 100mL / min, and the hydraulic retention time in the reactor being approximately 15min, to ensure that carbon dioxide is fully hydrolyzed into carbonate ions, inducing metal ion precipitation, and forming carbonate granulation bodies; the regenerated amphoteric electrolyte solution is circulated for metal ion leaching; and the tail gas is discharged when the CO2 content meets the emission standards after testing; otherwise, it is returned to the nuclear crystallization granulation reactor for reaction.

[0106] After treatment, the calcium ion concentration in the leachate was reduced to approximately 386 mg / L, the magnesium ion concentration to approximately 27 mg / L, the zinc ion concentration to approximately 13 mg / L, and the copper ion concentration to approximately 10 mg / L. The amount of carbonate precipitate generated was stable, achieving effective treatment of incineration fly ash and flue gas and resource recovery.

[0107] Example 3

[0108] This embodiment provides a method for treating incineration fly ash and flue gas. This embodiment is carried out in a medium-sized waste incineration plant. The main types of waste include domestic waste (about 80%), industrial waste (about 15%) and medical waste (about 5%).

[0109] The CO2 concentration in the boiler flue gas at this waste incineration plant is approximately 12%. The flue gas is first passed through a particulate filter to remove solid particles. The filtered flue gas then enters a pressure swing adsorption unit, where pressure fluctuations cause the adsorbent to absorb and release CO2, increasing the CO2 concentration from its original low concentration to approximately 38% by volume.

[0110] The incineration fly ash was mixed with a histidine solution with a concentration of 0.8 mol / L at a ratio of 250 g / L and stirred at 500 rpm for 1 hour to efficiently leach the metal ions in the fly ash. A centrifugal dehydrator was used to centrifuge at 7000 rpm for 10 minutes to achieve solid-liquid separation, and a leachate containing metal ions and purified fly ash were obtained. The purified fly ash was dried using a drying device and then landfilled in a landfill. The water quality of the leachate was analyzed using an inductively coupled plasma mass spectrometer, where Ca 2+ The concentration is about 4800mg / L, Pb 2+ The concentration is about 270mg / L, Mg 2+ The concentration is about 50mg / L, Cu 2+ The concentration is about 28mg / L.

[0111] 50L of leachate and CO2-rich waste gas are introduced into a nuclear crystallization granulation reactor equipped with nuclear crystallization granulation seeds FC-ac, with the seed filling height being 30% of the effective height of the reactor (the effective height being the height from the water inlet to the water outlet), the water inlet flow rate being 30L / h, the air inlet flow rate being 200mL / min, and the hydraulic retention time in the reactor being approximately 20min, to ensure that carbon dioxide is fully hydrolyzed into carbonate ions, inducing metal ion precipitation, and forming carbonate granulation bodies; the regenerated amphoteric electrolyte solution is circulated for metal ion leaching; and the tail gas is discharged when the CO2 content meets the emission standards after testing; otherwise, it is returned to the nuclear crystallization granulation reactor for reaction.

[0112] After treatment, the calcium ion concentration in the leachate was reduced to about 500 mg / L, the lead ion concentration was reduced to about 50 mg / L, the magnesium ion concentration was reduced to about 20 mg / L, and the copper ion concentration was reduced to about 13 mg / L. The carbonate precipitate was discharged in the form of granules, realizing the effective treatment of incineration fly ash and flue gas and the recycling of resources.

[0113] Example 4

[0114] This embodiment provides a method for treating incineration fly ash and flue gas. This embodiment is carried out in a large-scale waste incineration plant. The main types of waste include domestic waste (about 75%), industrial waste (about 20%) and medical waste (about 5%).

[0115] The CO2 concentration in the boiler flue gas at this waste incineration plant is approximately 14%. The flue gas is first passed through a particulate filter to remove solid particles. The filtered flue gas then enters a pressure swing adsorption unit, where pressure fluctuations cause the adsorbent to absorb and release CO2, increasing the CO2 concentration from its original low concentration to approximately 43% by volume.

[0116] The incineration fly ash was mixed with a glycine solution with a concentration of 1.2 mol / L at a ratio of 280 g / L and stirred at 600 rpm for 1 hour to efficiently leach the metal ions in the fly ash. A centrifugal dehydrator was used to centrifuge at 8000 rpm for 10 minutes to achieve solid-liquid separation, and a leachate containing metal ions and purified fly ash were obtained. The purified fly ash was dried using a drying device and then landfilled in a landfill. The water quality of the leachate was analyzed using an inductively coupled plasma mass spectrometer, where Ca 2+ Concentration is about 7200mg / L, Mg 2+ The concentration is about 380mg / L, Zn 2+ The concentration is about 70mg / L, Cu 2+ The concentration is about 30mg / L.

[0117] 50L of leachate and CO2-rich waste gas are introduced into a nuclear crystallization granulation reactor equipped with nuclear crystallization granulation seeds FC-ac, with the seed filling height being 30% of the effective height of the reactor (the effective height being the height from the water inlet to the water outlet), the water inlet flow rate being 60L / h, the air inlet flow rate being 400mL / min, and the hydraulic retention time in the reactor being approximately 30min, to ensure that carbon dioxide is fully hydrolyzed into carbonate ions, inducing metal ion precipitation, and forming carbonate granulation bodies; the regenerated amphoteric electrolyte solution is circulated for metal ion leaching; and the tail gas is discharged when the CO2 content meets the emission standards after testing; otherwise, it is returned to the nuclear crystallization granulation reactor for reaction.

[0118] After treatment, the calcium ion concentration in the leachate was reduced to about 800 mg / L, the magnesium ion concentration was reduced to about 90 mg / L, the zinc ion concentration was reduced to about 30 mg / L, and the copper ion concentration was reduced to about 17 mg / L. The carbonate precipitate was discharged in the form of granules, realizing the effective treatment of incineration fly ash and flue gas and the recycling of resources.

[0119] Example 5

[0120] This embodiment provides a method for treating incineration fly ash and flue gas, which differs from Example 2 only in that the concentration of the alanine solution is 0.3 mol / L.

[0121] The calcium ion concentration in the leachate of this embodiment is 1800 mg / L, the magnesium ion concentration is 103 mg / L, the zinc ion concentration is 21 mg / L, and the copper ion concentration is 15 mg / L.

[0122] The calcium ion concentration in the treated leachate is 760 mg / L, the magnesium ion concentration is 68 mg / L, the zinc ion concentration is 13 mg / L, and the copper ion concentration is 10 mg / L.

[0123] Compared with Example 2, the concentration of the alanine solution used in Example 5 is relatively low, and its metal ion leaching efficiency and CO2 mass transfer efficiency are relatively low, resulting in insufficient leaching of metal ions in the incineration fly ash, a decrease in the concentration of metal ions in the leachate, and a decrease in the metal ion removal rate after the leachate is treated.

[0124] Comparative Example 1

[0125] This comparative example provides a method for treating incineration fly ash and flue gas, which differs from Example 2 only in that the core crystal granulation seed FC-ac is replaced by ordinary seed garnet.

[0126] In the treated leachate of this embodiment, the calcium ion concentration is 1350 mg / L, the magnesium ion concentration is 87 mg / L, the zinc ion concentration is 16 mg / L, and the copper ion concentration is 14 mg / L.

[0127] Comparing Example 2 with Comparative Example 1, it can be seen that the metal ion removal efficiency of the core crystal granulation seeds used in the present invention is significantly higher than that of garnet. Furthermore, because the metal ions are converted into carbonates, the mineralization and fixation efficiency of carbon dioxide is also significantly higher than that of garnet.

[0128] The foregoing description is intended only to provide specific embodiments of the present disclosure, intended to enable those skilled in the art to understand and implement the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the embodiments described herein, but rather to be construed in the broadest manner consistent with the principles and novel features disclosed herein.

Claims

1. A method for treating incineration fly ash and flue gas by crystallization and granulation, characterized in that: The processing method comprises the following steps: Remove solid particles from the incineration flue gas and enrich the CO2 in the incineration flue gas to obtain CO2-rich waste gas; Leaching the metal ions in the incineration fly ash with an amphoteric electrolyte solution, separating the solid and the liquid to obtain a leachate containing metal ions and purified fly ash; In the presence of nucleation granulation seeds, the CO2-rich waste gas is introduced into the leachate to react, thereby obtaining carbonate granules, a regenerated ampholyte solution and tail gas; The nucleation granulation seed comprises a carrier material and alkaline active sites supported on the carrier material; The regenerated ampholyte solution is circulated for leaching metal ions in the incineration fly ash.

2. The processing method according to claim 1, characterized in that The removal of solid particles from the incineration flue gas is carried out using a particle filter.

3. The processing method according to claim 1, characterized in that The enrichment of CO2 in the incineration flue gas is carried out using a carbon dioxide enrichment device.

4. The processing method according to claim 3, characterized in that The carbon dioxide enrichment device includes one or more of a pressure swing adsorption device and a temperature swing adsorption device.

5. The processing method according to claim 1, characterized in that The volume content of CO2 in the CO2-rich waste gas is 35-45%.

6. The processing method according to claim 1, characterized in that The step of leaching the metal ions in the incineration fly ash comprises: mixing the amphoteric electrolyte solution with the incineration fly ash and stirring.

7. The processing method according to claim 6, characterized in that The stirring speed is 300-600 rpm; The stirring time is 0.5-2 h.

8. The processing method according to claim 1 or 6, characterized in that: The mass volume ratio of the incineration fly ash to the ampholyte solution is 200-300 g / L.

9. The processing method according to claim 1 or 6, characterized in that: The concentration of the ampholyte solution is 0.5-1.2 mol / L.

10. The processing method according to claim 1 or 6, characterized in that: The ampholytes include amino acids.

11. The processing method according to claim 1, characterized in that: The metal ions include one or more of calcium ions, magnesium ions, zinc ions, copper ions and lead ions.

12. The processing method according to claim 1, characterized in that: The solid-liquid separation is carried out using a centrifugal dehydrator.

13. The processing method according to claim 12, characterized in that: The centrifugal speed of the centrifugal dehydrator is 5000-8000 rpm, and the centrifugal time is 5-10 min.

14. The processing method according to claim 1, characterized in that The material of the basic active site includes one or more of an alkali metal oxide and an alkaline earth metal oxide.

15. The processing method according to claim 14, characterized in that: The alkali metal oxide includes one or more of Na2O, K2O and Rb2O, and the alkaline earth metal oxide includes CaO.

16. The processing method according to claim 1, characterized in that The support material includes one or more of alumina, molecular sieve, zeolite, activated carbon and mesoporous silica.

17. The processing method according to claim 1, characterized in that: The ratio of the volume of CO2 in the CO2-rich waste gas to the molar amount of metal ions in the leachate is 0.28-0.4 L / mol.

18. The processing method according to claim 1, characterized in that The reaction time is more than 10 min.

19. The processing method according to claim 1, characterized in that The step of forming the carbonate granulation body is carried out in a nucleation granulation reactor.

20. The processing method according to claim 1, characterized in that The treatment method further comprises: drying the purified fly ash and then landfilling it; And / or, detecting the CO2 content in the tail gas, and discharging the CO2 when the CO2 content reaches the emission standard; when the CO2 content does not reach the emission standard, returning the tail gas to react with the leachate.

21. A nuclear crystal granulation processing system for incineration fly ash and flue gas, characterized in that: The processing system comprises: Particle filter, used to remove solid particles from incineration flue gas; a carbon dioxide enrichment device, the inlet of which is connected to the outlet of the particle filter, for enriching CO2 and generating CO2-rich exhaust gas; Fly ash washing device, used to leach metal ions from incineration fly ash using an amphoteric electrolyte solution; a centrifugal dehydration device, the inlet of which is connected to the outlet of the fly ash washing device, for solid-liquid separation to obtain leachate and purify fly ash; and Nucleation granulation reactor; The nucleation granulation reactor comprises a reactor body, on which is provided: a water inlet for introducing the leachate separated by the centrifugal dehydration device; An air inlet, for introducing the CO2-rich waste gas generated by the carbon dioxide enrichment device; A water outlet, used to discharge the purified liquid; An air outlet for discharging exhaust gas; A crystal discharge port is used to discharge the granules generated in the nuclear crystal granulation reactor; The nuclear crystal granulation reactor is equipped with nuclear crystal granulation seeds.

22. The processing system according to claim 21, characterized in that The water outlet of the core crystal granulation reactor is connected to the inlet of the fly ash washing device.

23. The processing system according to claim 21, characterized in that The gas outlet of the core crystal granulation reactor is connected to at least two pipelines, one of which is connected to the gas inlet of the core crystal granulation reactor.

24. The processing system according to claim 21, wherein The carbon dioxide enrichment device includes one or more of a pressure swing adsorption device and a temperature swing adsorption device.

25. The processing system according to claim 21, wherein The processing system further comprises a CO2 monitoring unit for monitoring the CO2 content in the tail gas discharged from the core crystal granulation reactor.

26. The processing system according to claim 21, wherein The processing system further includes a drying device for drying the purified fly ash separated by the centrifugal dehydration device.

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