Resource utilization method of coal gasification fine slag

Abstract

The invention relates to the technical field of coal-based solid waste resource utilization, and discloses a resource utilization method of coal gasification fine slag. The method comprises the following steps: (1) pretreating the gasified fine slag, then mixing the pretreated gasified fine slag with an acid solution, and then carrying out ultrasonic cavitation treatment on the obtained mixture; (2) in the presence of a grey water dispersing agent and cationic polyacrylamide, performing dispersion stabilization treatment and selective flocculation separation on the material obtained in the step (1), and then performing gravity settling on the treated material to obtain a carbon-rich material; (3) mixing the carbon-rich material with a boron source, and then roasting to obtain a boron modified material; and (4) carrying out purification treatment on organic wastewater by using the boron modified material. The method has the characteristics of high carbon ash separation efficiency, simple process flow and low medicament consumption, and provides a solution with industrial potential for coal-based solid waste recycling and organic wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of coal-based solid waste resource utilization technology, specifically to a method for the resource utilization of coal gasification fine slag. Background Technology

[0002] Gasification technology, as a core process in modern coal chemical industry, generates a large amount of solid waste—coal gasification slag—during production. Its formation mechanism is as follows: Coal-water slurry or pulverized coal reacts with oxygen and steam at high temperatures in an entrained gasifier to generate syngas. The molten slag produced during the reaction, after cooling, clearly separates into two parts: one is coarse slag directly discharged from the bottom of the furnace; the other is fine granular slag carried away by the syngas and collected in subsequent processes, i.e., gasification fine slag.

[0003] The amount of fine gasification slag produced accounts for approximately 40%-60% of the total coal gasification slag. This fine slag undergoes multi-stage circulating washing before entering the black water treatment system, forming a fine slag slurry. It then undergoes flocculation sedimentation and vacuum filtration dewatering treatment, ultimately yielding a filter cake-like material with a moisture content as high as 50%-60%. Statistics show that my country's annual production of fine coal gasification slag exceeds 80 million tons, with a residual carbon content consistently between 20% and 35%.

[0004] Microstructural analysis reveals that the porous residual carbon and aluminosilicate glass in the gasification slag form a complex "melt-embedding" structure during high-temperature melting—the ash components largely fill or adhere to the carbonaceous pores. This tight binding directly leads to a significant reduction in the separation efficiency of traditional physical sorting methods. Furthermore, the gasification slag itself is characterized by high moisture content, high ash content, fine particle size, and complex composition, posing a severe challenge to its large-scale resource utilization. Currently, my country's disposal of gasification slag primarily involves blending it into building materials or direct landfilling, failing to fully exploit its resource value and maximize its utilization.

[0005] Therefore, there is an urgent need to develop a carbon-ash separation technology for coal gasification fine slag that has high carbon-ash separation efficiency, simple process flow, and low reagent consumption, so as to realize the efficient resource utilization of coal gasification fine slag. Summary of the Invention

[0006] The purpose of this invention is to overcome the problem in existing technologies where the porous residual carbon and ash components of coal gasification fine slag are difficult to separate efficiently, thus hindering the maximization of resource utilization. This invention provides a method for the resource utilization of coal gasification fine slag. This method features high carbon-ash separation efficiency, a simple process flow, and low reagent consumption. Furthermore, through multi-process synergistic optimization, it achieves a short-process conversion of gasification fine slag from solid waste to a high-efficiency catalyst, providing an industrially viable solution for the resource utilization of coal-based solid waste and the treatment of organic wastewater.

[0007] To achieve the above objectives, the present invention provides a method for the resource utilization of coal gasification fine slag, the method comprising the following steps:

[0008] (1) Pre-treat the gasification fine slag, then mix the pre-treated gasification fine slag with an acid solution, and then subject the resulting mixture to ultrasonic cavitation treatment.

[0009] (2) In the presence of ash water dispersant and cationic polyacrylamide, the material obtained in step (1) is subjected to dispersion stabilization treatment and selective flocculation separation, and then the treated material is subjected to gravity sedimentation to obtain carbon-rich material.

[0010] (3) The carbon-rich material is mixed with a boron source and then calcined to obtain a boron-modified material;

[0011] (4) Use the boron-modified material to purify organic wastewater.

[0012] Preferably, in step (1), the solid-liquid ratio of the pretreated gasified fine residue to the acid solution is 1g:1-10mL.

[0013] Preferably, the acid in the acid solution is at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0014] Preferably, the concentration of the acid solution is 6-20 wt%.

[0015] Preferably, in step (1), the conditions for ultrasonic cavitation treatment include: power of 300-500W and time of 5-30min.

[0016] Preferably, in step (2), the specific process of dispersing and stabilizing the material obtained in step (1) and selectively flocculating and separating it includes: first mixing and contacting the material obtained in step (1) with the ash water dispersant, and then second mixing and contacting it with the cationic polyacrylamide.

[0017] Preferably, the conditions for the first mixing contact include: a stirring speed of 300-600 rpm and a time of 5-30 min.

[0018] Preferably, the conditions for the second mixing contact include: a stirring speed of 300-600 rpm and a time of 5-30 min.

[0019] Preferably, the solid-liquid ratio of the pretreated gasified fine slag to the ash-water dispersant is 1t:100-500L.

[0020] Preferably, the ash water dispersant is selected from at least one of acrylic acid-maleic acid copolymers, polycarboxylic acids, and β-cyclodextrin polymers.

[0021] Preferably, the mass ratio of the pretreated gasification slag to the cationic polyacrylamide is 1t:50-150g.

[0022] Preferably, the cationic polyacrylamide has a molecular weight of 8-12 million.

[0023] Preferably, the cationic polyacrylamide is used in the form of a cationic polyacrylamide solution, and the concentration of the cationic polyacrylamide solution is 0.2-1 wt‰.

[0024] Preferably, in step (3), the mass ratio of the carbon-rich material to the boron source is 100:5-30.

[0025] Preferably, the boron source is selected from at least one of boric acid, boron oxide, and borax.

[0026] Preferably, in step (3), the calcination conditions include: a heating rate of 1-10℃ / min, a temperature of 500-850℃, and a time of 2-5h.

[0027] Preferably, in step (4), the purification process includes: mixing the boron-modified material with the organic wastewater and pre-treating it by adsorption for 10-60 minutes, and then adding the persulfate to the system for treatment for 1-5 hours.

[0028] Preferably, the solid-liquid ratio of the boron-modified material to the organic wastewater is 0.05-0.3 g: 1 L.

[0029] Preferably, the molar ratio of the persulfate to the volume of the organic wastewater is 1-12 mmol:1L.

[0030] Preferably, the mass ratio of the boron-modified material to the persulfate is 1:3-10.

[0031] Preferably, the persulfate is selected from at least one of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0032] The method described in this invention couples carbon ash separation with catalyst precursor pretreatment. An acid solution is introduced during ultrasonic treatment, which efficiently promotes carbon ash dissociation while selectively dissolving metals and inorganic minerals from the gasification slag. This process not only significantly optimizes carbon ash separation but also simultaneously reconstructs the pore structure and modulates the surface properties of carbon-rich components, laying a solid foundation for the precise construction of subsequent catalytic active sites. Furthermore, the amount of dispersant and flocculant used is reduced by 50%-70% compared to traditional flotation processes, and repeated acid-base washing pretreatment is eliminated when preparing catalysts from carbon-rich materials, greatly simplifying the overall process.

[0033] Simultaneously, boron was selected as a non-metallic dopant to perform targeted modification of the carbon-rich material from gasification slag. The stable embedding of boron into the carbon framework provides active sites for specific boron-carbon and boron-oxidation chemical bonds. These sites significantly enhance the material's electron conductivity, thereby efficiently promoting the electron transfer process between persulfate (PDS) and organic pollutants.

[0034] Furthermore, during the degradation of organic matter in this catalytic system, various active species are generated, including free radicals (·OH, etc.) and non-free radicals (…). 1 O2), and these two work synergistically to degrade the target pollutants. Meanwhile, because 1 O2 is not easily quenched by common anions (such as Cl-) in organic wastewater, thus it can degrade organic pollutants in organic wastewater. Through synergistic optimization of multiple processes, a short-process conversion of gasification slag from industrial solid waste to a high-efficiency catalyst has been successfully achieved, providing an integrated solution with both technical feasibility and industrialization potential for the resource utilization of coal-based solid waste and the deep treatment of organic wastewater. Attached Figure Description

[0035] Figure 1 This is a graph showing the changes in phenol degradation rate before and after the addition of different quenchers;

[0036] Figure 2 This is a graph showing the changes in the degradation rate of bisphenol A before and after the addition of different quenchers. Detailed Implementation

[0037] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0038] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0039] The method for resource utilization of coal gasification fine slag according to the present invention includes the following steps:

[0040] (1) Pre-treat the gasification fine slag, then mix the pre-treated gasification fine slag with an acid solution, and then subject the resulting mixture to ultrasonic cavitation treatment.

[0041] (2) In the presence of ash water dispersant and cationic polyacrylamide, the material obtained in step (1) is subjected to dispersion stabilization treatment and selective flocculation separation, and then the treated material is subjected to gravity sedimentation to obtain carbon-rich material.

[0042] (3) The carbon-rich material is mixed with a boron source and then calcined to obtain a boron-modified material;

[0043] (4) Use the boron-modified material to purify organic wastewater.

[0044] In some embodiments, the specific process of the pretreatment in step (1) includes: placing the coal gasification slag in an electric heating blast drying oven and drying it at 90-110℃ for 10-30 hours; the dried material is screened through a standard sieve with a pore size of 0.5mm, and the undersize material is the pretreated gasification fine slag.

[0045] In some embodiments, in step (1), the solid-liquid ratio of the pretreated gasified fine residue to the acid solution is 1g:1-10mL, preferably 1g:1-8mL, and more preferably 1g:1.5-5mL.

[0046] In the method described in this invention, the acid solution can dissolve metal oxides in the ash while simultaneously etching the surface of residual carbon to form abundant slit-like mesopores. Preferably, the acid in the acid solution is at least one of hydrochloric acid, sulfuric acid, and nitric acid. More preferably, the acid in the acid solution is hydrochloric acid.

[0047] In some preferred embodiments, the concentration of the acid solution is 6-20 wt%, preferably 10-15 wt%.

[0048] In the method described in this invention, in step (1), ultrasonic cavitation can effectively disrupt the tightly intercalated structure of carbon and ash in the gasified fine slag, and the ash particles cross-linked with the surface of residual carbon are effectively stripped off, significantly improving the separation efficiency and greatly reducing the reagent dependence of traditional flotation processes; the acid solution simultaneously dissolves the metal oxides in the ash and etches the surface of residual carbon to form abundant slit-like mesopores; achieving a three-in-one process of "dissociation-pore formation-activation", laying the foundation for subsequent separation and catalytic site construction. In a preferred embodiment, the conditions for ultrasonic cavitation treatment include: power of 300-500W, preferably 350-450W; and time of 5-30min, preferably 10-25min.

[0049] In some specific implementations, in order to dilute the acid concentration of the system, reduce the risk of equipment corrosion, and build a suitable liquid phase environment for subsequent processing, the specific process of step (1) may also include: adding deionized water to the ultrasonic cavitation reaction system, adjusting the solid-liquid ratio of the system to 30-50 g / L, and continuing ultrasonic treatment for 15-30 min to promote the deep desorption and release of ash encapsulated in the residual carbon and enhance the dissociation effect of the carbon-ash interface.

[0050] In some embodiments, the specific process of dispersing and stabilizing the material obtained in step (1) and selectively flocculating and separating it in step (2) includes: first mixing and contacting the material obtained in step (1) with the ash water dispersant, and then second mixing and contacting it with the cationic polyacrylamide.

[0051] In the method described in this invention, residual carbon and ash particles have been initially separated in the ultrasonicated system. The ash water dispersant, as a high-molecular-weight polymer, has its molecular chains adsorbed onto the particle surface through steric hindrance, forming a stable polymer coating layer. This effectively disintegrates residual carbon-ash agglomerates, allowing the residual carbon and ash to fully dissociate and expose their respective pure surfaces. Simultaneously, it generates strong electrostatic repulsion and steric hindrance on the particle surface, keeping the entire suspension system in a highly dispersed and stable state, greatly delaying particle sedimentation and creating a crucial "time window" for subsequent separation based on sedimentation velocity differences.

[0052] In some preferred embodiments, the ash water dispersant is selected from at least one of acrylic acid-maleic acid copolymers, polycarboxylic acids, and β-cyclodextrin polymers. In a further preferred embodiment, the ash water dispersant is an acrylic acid-maleic acid copolymer.

[0053] In some embodiments, the solid-liquid ratio of the pretreated gasified fine slag to the ash-water dispersant is 1t:100-500L, preferably 1t:150-450L, and more preferably 1t:200-400L.

[0054] In some specific embodiments, in step (2), the conditions for the first mixing contact include: a stirring speed of 300-600 rpm, preferably 400-500 rpm; and a time of 5-30 min, preferably 15-25 min.

[0055] In the method described in this invention, the long molecular chains of the cationic polyacrylamide (CPAM) carry a positive charge. In the system modified with the ash dispersant, the surface of the residual carbon is usually weakly negatively charged or highly hydrophobic, while the surface properties of the ash particles (such as quartz and mullite) are also altered. Low doses of CPAM preferentially adsorb onto the more hydrophobic and appropriately sized residual carbon particles through bridging, while having a weak effect on highly dispersed ash particles. The residual carbon particles adsorbed with CPAM rapidly form "bridges," generating larger, denser flocs; the ash particles, still under the stabilizing effect of the dispersant, remain in a fine particle state. Thus, the apparent particle size and density of the residual carbon flocs increase, and their settling velocity significantly increases, while the ash particles settle extremely slowly, creating a huge difference in settling velocity between the two.

[0056] In some preferred embodiments, the cationic polyacrylamide has a molecular weight of 8-12 million, more preferably 8-10 million.

[0057] In some embodiments, the mass ratio of the pretreated gasified slag to the cationic polyacrylamide is 1t:50-150g, preferably 1t:60-140g, and more preferably 1t:80-120g.

[0058] In some specific embodiments, in step (2), the cationic polyacrylamide is used in the form of a cationic polyacrylamide solution, which is a mixture of cationic polyacrylamide and water, and the concentration of the cationic polyacrylamide solution is 0.2-1 wt‰, preferably 0.3-0.8 wt‰.

[0059] In some specific embodiments, in step (2), the conditions for the second mixing contact include: a stirring speed of 300-600 rpm, preferably 400-500 rpm; and a time of 5-30 min, preferably 10-25 min.

[0060] In some specific embodiments, the gravity sedimentation process in step (2) further includes: after standing for 5-10 minutes, the rapidly settling carbon flocs are collected as carbon-rich products, and the suspended ash is discharged as ash-rich products. After filtration and drying, low-ash carbon-rich materials and high-ash ash-rich materials are obtained. In this invention, the ash-rich materials can be used as mesoporous adsorbents and cementing materials, etc.

[0061] In some embodiments, in step (3), the mass ratio of the carbon-rich material to the boron source is 100:5-30, preferably 100:10-25. Specifically, the mass ratio of the carbon-rich material to the boron source can be 100:10, 100:12, 100:14, 100:15, 100:16, 100:18, 100:20, 100:22, 100:24, or 100:25.

[0062] In the method described in this invention, the boron source serves as a non-metallic dopant to directionally modify the carbon-rich material, causing boron to be doped into the carbon framework, forming stable chemical bonds and key active sites. These sites can effectively reduce the activation barrier of persulfate, promoting its efficient and stable conversion into singlet oxygen (…). 1 Active species, mainly O2.

[0063] In some preferred embodiments, the boron source is selected from at least one of boric acid, boron oxide, and borax. In a further preferred embodiment, the boron source is boric acid.

[0064] In some specific embodiments, in step (3), the calcination conditions include: a heating rate of 1-10℃ / min, preferably 3-7℃ / min; a temperature of 500-850℃, preferably 600-850℃; and a time of 2-5h, preferably 2-4h.

[0065] In the method described in this invention, the surface of the boron-modified material generates a large number of porous structures, which can better adsorb, oxidize and degrade pollutants. At the same time, the number of oxygen-containing functional groups increases significantly, forming stable chemical bonds and key active sites.

[0066] In some embodiments, in step (4), the purification process includes: mixing the boron-modified material with the organic wastewater and pre-treating it by adsorption for 10-60 minutes, and then adding the persulfate to the system for treatment for 1-5 hours. In this invention, the organic wastewater is coal gasification phenol-ammonia wastewater, mainly containing: phenolic compounds, ammonia nitrogen, cyanide, polycyclic aromatic hydrocarbons, tar, and others. Among them, phenol, cresol, and polyphenols (such as bisphenol A) account for a large proportion and are the main organic pollutants.

[0067] In the method described in this invention, the boron-modified material exhibits a greater number of porous structures on its surface, enabling better adsorption, oxidation, and degradation of pollutants. Simultaneously, the number of oxygen-containing functional groups significantly increases, forming stable chemical bonds and key active sites. These sites effectively lower the activation barrier of persulfate, promoting its efficient and stable conversion into singlet oxygen (…). 1 Active species, primarily composed of O2. 1 O2-dominated non-radical oxidation, supplemented by the synergistic effect of free radicals (·OH, etc.). This non-radical-dominated pathway is the key advantage of this technology because... 1 O2 is not easily quenched by common anions (such as Cl-) in organic wastewater, thus ensuring that the catalytic system can still maintain a high efficiency in degrading organic matter in saline environments.

[0068] In some embodiments, in step (4), the solid-liquid ratio of the boron-modified material to the organic wastewater is 0.05-0.3 g:1 L, preferably 0.1-0.3 g:1 L. As a specific example, the solid-liquid ratio of the boron-modified material to the organic wastewater can be 0.1 g:1 L, 0.15 g:1 L, 0.2 g:1 L, 0.25 g:1 L, or 0.3 g:1 L.

[0069] In some embodiments, in step (4), the ratio of the amount of persulfate to the volume of the organic wastewater is 1-12 mmol:1L, preferably 2-10 mmol:1L, and more preferably 4-8 mmol:1L.

[0070] In some embodiments, in step (4), the mass ratio of the boron-modified material to the persulfate is 1:3-10, preferably 1:4-9.8. Specifically, the mass ratio of the boron-modified material to the persulfate is 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:9.5, or 1:9.8.

[0071] In some preferred embodiments, the persulfate is selected from at least one of sodium persulfate, potassium persulfate, and ammonium persulfate. In a further preferred embodiment, the persulfate is sodium persulfate.

[0072] The following examples further illustrate the resource utilization method of coal gasification fine slag according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0073] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0074] In the following examples and comparative examples, the coal gasification slag was sourced from Ningxia Coal Industry Co., Ltd. (the pretreated coal gasification slag had a carbon content of 23.1 wt%, an ash content of 74.52 wt%, and a pore volume of 0.2824 cm³). 3 / g); Acrylic acid-maleic acid copolymer was purchased from Hubei Shishun Biotechnology Co., Ltd.; Cationic polyacrylamide was purchased from Gongyi Xinqi Polymer Co., Ltd., with a molecular weight of 8-10 million; Organic wastewater came from Ningdong Energy and Chemical Base in Ningxia Hui Autonomous Region.

[0075] Example 1

[0076] (1) The coal gasification slag was placed in an electric heating blast drying oven and dried at 100℃ for 24 hours. The dried material was screened through a standard sieve with a pore size of 0.5 mm, and the undersize material was the pretreated gasification fine slag. The pretreated gasification fine slag was mixed with a 10wt% hydrochloric acid solution at a solid-liquid ratio of 1g:3mL and ultrasonically treated at 400W for 20 minutes. Then, deionized water was added to the ultrasonic reaction system to adjust the solid-liquid ratio of the system to 40g / L, and ultrasonic treatment was continued for 20 minutes.

[0077] (2) The material obtained in step (1) is mixed with acrylic acid-maleic acid copolymer and stirred at 450 rpm for 20 min; then a cationic polyacrylamide solution with a concentration of 0.5 wt‰ is added and stirred at 450 rpm for 20 min; after standing for 8 min, the rapidly settling carbon flocs are collected as carbon-rich products and the suspended ash is discharged as ash-rich products. After filtration and drying, low-ash carbon-rich materials and high-ash ash-rich materials are obtained.

[0078] The solid-liquid ratio of the pretreated gasification slag to the acrylic acid-maleic acid copolymer is 1t:300L; the mass ratio of the pretreated gasification slag to the cationic polyacrylamide is 1t:100g.

[0079] (3) The carbon-rich material is mixed with boric acid at a mass ratio of 100:20, and after thorough grinding, it is transferred to a crucible; the crucible is sealed and placed in a muffle furnace and heated to 800°C at a heating rate of 5°C / min, and kept at a constant temperature for 3 hours; after the furnace cools naturally to room temperature, the boron-modified material is obtained.

[0080] (4) The boron-modified material and the organic wastewater were mixed at a solid-liquid ratio of 0.2 g: 1 L and pretreated by adsorption for 30 min. Then, sodium persulfate was added to the system and treated for 2 h. The molar ratio of sodium persulfate to the volume of the organic wastewater was 4 mmol: 1 L, and the mass ratio of the boron-modified material to sodium persulfate was 1: 4.76.

[0081] Example 2

[0082] (1) The coal gasification slag was placed in an electric heating blast drying oven and dried at 100℃ for 24 hours. The dried material was screened through a standard sieve with a pore size of 0.5 mm, and the undersize material was the pretreated gasification fine slag. The pretreated gasification fine slag was mixed with a 12wt% hydrochloric acid solution at a solid-liquid ratio of 1 g: 1.5 mL and ultrasonically treated at 350 W for 25 min. Then, deionized water was added to the ultrasonic reaction system to adjust the solid-liquid ratio of the system to 30 g / L, and ultrasonic treatment was continued for 30 min.

[0083] (2) The material obtained in step (1) is mixed with acrylic acid-maleic acid copolymer and stirred at 400 rpm for 25 min; then a cationic polyacrylamide solution with a concentration of 0.3 wt‰ is added and stirred at 400 rpm for 25 min; after standing for 10 min, the rapidly settling carbon flocs are collected as carbon-rich products and the suspended ash is discharged as ash-rich products. After filtration and drying, low-ash carbon-rich materials and high-ash ash-rich materials are obtained.

[0084] The solid-liquid ratio of the pretreated gasification slag to the acrylic acid-maleic acid copolymer is 1t:200L; the mass ratio of the pretreated gasification slag to the cationic polyacrylamide is 1t:80g.

[0085] (3) The carbon-rich material is mixed with boric acid at a mass ratio of 100:10, and after thorough grinding, it is transferred to a crucible; the crucible is sealed and placed in a muffle furnace and heated to 600°C at a heating rate of 3°C / min, and kept at a constant temperature for 4 hours; after the furnace cools naturally to room temperature, the boron-modified material is obtained.

[0086] (4) The boron-modified material and the organic wastewater are mixed at a solid-liquid ratio of 0.2 g: 1 L and pretreated by adsorption for 30 min. Then, sodium persulfate is added to the system and treated for 2 h. The molar ratio of sodium persulfate to the volume of the organic wastewater is 6 mmol: 1 L, and the mass ratio of the boron-modified material to sodium persulfate is 1: 7.14.

[0087] Example 3

[0088] (1) The coal gasification slag was placed in an electric heating blast drying oven and dried at 100℃ for 24 hours. The dried material was screened through a standard sieve with a pore size of 0.5 mm, and the undersize material was the pretreated gasification fine slag. The pretreated gasification fine slag was mixed with a 15wt% hydrochloric acid solution at a solid-liquid ratio of 1g:5mL and ultrasonically treated for 10min at a power of 450W. Then, deionized water was added to the ultrasonic reaction system to adjust the solid-liquid ratio of the system to 50g / L, and ultrasonic treatment was continued for 15min.

[0089] (2) The material obtained in step (1) is mixed with acrylic acid-maleic acid copolymer and stirred at 500 rpm for 15 min; then a cationic polyacrylamide solution with a concentration of 0.8 wt‰ is added and stirred at 500 rpm for 10 min; after standing for 5 min, the rapidly settling carbon flocs are collected as carbon-rich products and the suspended ash is discharged as ash-rich products. After filtration and drying, low-ash carbon-rich materials and high-ash ash-rich materials are obtained.

[0090] The solid-liquid ratio of the pretreated gasification slag to the acrylic acid-maleic acid copolymer is 1t:400L; the mass ratio of the pretreated gasification slag to the cationic polyacrylamide is 1t:120g.

[0091] (3) The carbon-rich material is mixed with boric acid at a mass ratio of 100:25, and after thorough grinding, it is transferred to a crucible; the crucible is sealed and placed in a muffle furnace and heated to 850°C at a heating rate of 7°C / min, and kept at a constant temperature for 2 hours; after the furnace is naturally cooled to room temperature, the boron-modified material is obtained.

[0092] (4) The boron-modified material and the organic wastewater are mixed at a solid-liquid ratio of 0.2 g: 1 L and pretreated by adsorption for 30 min. Then, sodium persulfate is added to the system and treated for 2 h. The molar ratio of sodium persulfate to the volume of the organic wastewater is 8 mmol: 1 L, and the mass ratio of the boron-modified material to persulfate is 1: 9.52.

[0093] Example 4

[0094] The method described in Example 1 is implemented, except that in step (2), an equal mass of sodium polyepoxysuccinate (Hubei Shixing Chemical Co., Ltd.) is used to replace the acrylic acid-maleic acid copolymer to obtain a boron-modified material, which is then used to purify organic wastewater.

[0095] Example 5

[0096] The method described in Example 1 is implemented, except that in step (2), cationic polyacrylamide with a molecular weight of 6 million (Gongyi Xinqi Polymer Co., Ltd.) is used instead of cationic polyacrylamide with a molecular weight of 8 million-10 million to obtain boron-modified material, and this material is used to purify organic wastewater.

[0097] Example 6

[0098] The method described in Example 1 is implemented, except that in step (3), the mass ratio of the carbon-rich material to boric acid is 100:40 to obtain a boron-modified material, which is then used to purify organic wastewater.

[0099] Example 7

[0100] The method described in Example 1 is implemented, except that in step (4), the mass ratio of the boron-modified material to sodium persulfate is 1:14.3 to obtain the boron-modified material, which is then used to purify organic wastewater.

[0101] Comparative Example 1

[0102] The method described in Example 1 is implemented, except that step (1) is omitted to obtain a boron-modified material, which is then used to purify organic wastewater.

[0103] Comparative Example 2

[0104] The method described in Example 1 is implemented, except that in step (2), no dispersion stabilization treatment is performed to obtain boron-modified material, which is then used to purify organic wastewater.

[0105] Comparative Example 3

[0106] The method described in Example 1 is implemented, except that in step (2), selective flocculation separation is not performed to obtain boron-modified material, and the material is used to purify organic wastewater.

[0107] Comparative Example 4

[0108] The method described in Example 1 is implemented, except that steps (1) and (2) are omitted. An equal amount of pretreated gasification slag is used to replace the carbon-rich material for modification, resulting in a boron-modified material, which is then used to purify organic wastewater.

[0109] Test case

[0110] Test Example 1

[0111] (1) Ash content of the carbon-rich materials prepared in the embodiments and comparative examples of the present invention and pore volume of the boron-modified materials (cm³) 3 / g) as shown in Table 1.

[0112] (2) In this invention, the mass concentrations of phenol and bisphenol A in the wastewater before and after purification were determined using a high-performance liquid chromatography (HPLC) instrument. The degradation rate was calculated using the formula: Degradation rate = (Initial concentration - Residual concentration) / Initial concentration × 100%. The results are shown in Table 1. The specific test parameters are as follows: For phenol, the mobile phase was methanol:water = 6:4, the flow rate was 1 mL / min, the column temperature was 30℃ (C18 column), and the detection wavelength was 270 nm; for bisphenol A, the mobile phase was water:acetonitrile = 1:1, the flow rate was 0.8 mL / min, the column temperature was 30℃ (C18 column), and the detection wavelength was 279 nm.

[0113] Table 1

[0114]

[0115]

[0116] As demonstrated in Examples 1-3, the solid waste-based carbon catalyst provided by this invention, prepared from gasified fine slag as raw material through acid washing, selective flocculation separation, and boron doping modification, exhibits excellent degradation performance for phenol and bisphenol A in organic wastewater. Under optimized conditions (Examples 1-3), the boron-modified material prepared by this method shows excellent removal efficiency (>90%) for typical organic pollutants (phenol, bisphenol A).

[0117] A comparison of Examples 1-3 and Comparative Examples 1-4 shows that a complete pretreatment process (acid washing, dispersion, selective flocculation) is crucial for obtaining high-performance catalysts. Materials prepared without acid washing (Comparative Example 1) or without effective carbon-ash separation (Comparative Examples 2-4) exhibit significantly increased ash content (>50%) and decreased pore volume, leading to reduced catalytic performance. The efficient separation of carbon materials from the gasification slag serves as a carbonaceous framework, laying the foundation for subsequent boron doping modification and the construction of abundant active sites.

[0118] A comparison of Examples 1-3 and Examples 4-7 shows that pretreatment and modification conditions significantly affect catalyst performance. Lower ash content in the carbon-rich material and larger pore volume in the boron-modified material result in better degradation effects. This is because low ash content ensures the purity of the carbon skeleton and the density of active sites, while high pore volume promotes mass transfer and contact with pollutants.

[0119] Test Example 2

[0120] In the process of purifying organic wastewater using the boron-modified material prepared in Example 1, the present invention adds... 1 O2 quenchers furfuryl alcohol (FFA), ·OH and SO4· - Quenchers methanol (MeOH) and superoxide radicals (-O2) - The quenching agent was used to quench benzoquinone (p-BQ) in a quenching experiment, and the results were compared with a blank test without any quenching agent. Figure 1 and Figure 2 As shown. Among them, Figure 1 The graph shows the changes in phenol degradation rate before and after the addition of different quenchers; Figure 2 The graph shows the changes in the degradation rate of bisphenol A before and after the addition of different quenchers.

[0121] pass Figure 1 and Figure 2 The results show that 1 The addition of the O2 quencher furfuryl alcohol (FFA) caused a sharp decrease in the degradation rate of phenol and bisphenol A, proving that... 1 O2 is the dominant active species in the degradation process. 1 O2 is an electrophilic species, and bisphenol A, with its electron-rich biphenyl ring structure, is more susceptible to attack than phenol, which is consistent with its higher degradation rate in all experiments. 1 The O2-dominated non-radical oxidation pathway is the main reason for achieving efficient degradation.

[0122] In summary, this invention transforms gasification slag into a carbon material with optimized pore structure and surface properties. This material can efficiently activate persulfate, generating... 1O2-dominant reactive oxygen species enable rapid and selective oxidative degradation of organic pollutants in organic wastewater. The entire technical solution embodies the concept of "treating waste with waste," combining high efficiency and practicality.

[0123] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for the resource utilization of fine coal gasification slag, characterized in that, The method includes the following steps: (1) Pre-treat the gasification fine slag, then mix the pre-treated gasification fine slag with an acid solution, and then subject the resulting mixture to ultrasonic cavitation treatment. (2) In the presence of ash water dispersant and cationic polyacrylamide, the material obtained in step (1) is subjected to dispersion stabilization treatment and selective flocculation separation, and then the treated material is subjected to gravity sedimentation to obtain carbon-rich material. (3) The carbon-rich material is mixed with a boron source and then calcined to obtain a boron-modified material; (4) Use the boron-modified material to purify organic wastewater.

2. The method according to claim 1, characterized in that, In step (1), the solid-liquid ratio of the pretreated gasified fine residue to the acid solution is 1g:1-10mL; Preferably, the acid in the acid solution is at least one of hydrochloric acid, sulfuric acid, and nitric acid; Preferably, the concentration of the acid solution is 6-20 wt%.

3. The method according to claim 1 or 2, characterized in that, In step (1), the conditions for ultrasonic cavitation treatment include: power of 300-500W and time of 5-30min.

4. The method according to claim 1, characterized in that, In step (2), the specific process of dispersing and stabilizing the material obtained in step (1) and selectively flocculating and separating it includes: first mixing and contacting the material obtained in step (1) with the ash water dispersant, and then second mixing and contacting it with the cationic polyacrylamide; Preferably, the conditions for the first mixing contact include: a stirring speed of 300-600 rpm and a time of 5-30 min; Preferably, the conditions for the second mixing contact include: a stirring speed of 300-600 rpm and a time of 5-30 min.

5. The method according to claim 1 or 4, characterized in that, The solid-liquid ratio of the pretreated gasified fine slag to the ash-water dispersant is 1t:100-500L; Preferably, the ash water dispersant is selected from at least one of acrylic acid-maleic acid copolymers, polycarboxylic acids, and β-cyclodextrin polymers.

6. The method according to claim 1 or 4, characterized in that, The mass ratio of the pretreated gasification slag to the cationic polyacrylamide is 1t:50-150g; Preferably, the cationic polyacrylamide has a molecular weight of 8-12 million; Preferably, the cationic polyacrylamide is used in the form of a cationic polyacrylamide solution, and the concentration of the cationic polyacrylamide solution is 0.2-1 wt‰.

7. The method according to claim 1, characterized in that, In step (3), the mass ratio of the carbon-rich material to the boron source is 100:5-30; Preferably, the boron source is selected from at least one of boric acid, boron oxide, and borax.

8. The method according to claim 1 or 7, characterized in that, In step (3), the calcination conditions include: a heating rate of 1-10℃ / min, a temperature of 500-850℃, and a time of 2-5h.

9. The method according to claim 1, characterized in that, In step (4), the purification process includes: mixing the boron-modified material with the organic wastewater and pre-treating it by adsorption for 10-60 min, and then adding persulfate to the system for treatment for 1-5 h; Preferably, the solid-liquid ratio of the boron-modified material to the organic wastewater is 0.05-0.3 g: 1 L; Preferably, the molar ratio of the persulfate to the volume of the organic wastewater is 1-12 mmol:1L.

10. The method according to claim 9, characterized in that, The mass ratio of the boron-modified material to the persulfate is 1:3-10; Preferably, the persulfate is selected from at least one of sodium persulfate, potassium persulfate, and ammonium persulfate.

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