A method for high-value resource utilization of gasified slag

Abstract

This invention discloses a method for high-value resource utilization of gasification slag, relating to the field of solid waste resource treatment, comprising the following steps: dissolving the gasification slag with acid to precipitate metals; filtering the acid-dissolved solution multiple times to extract useful metals; placing the acid-treated residue in a microwave oven cavity for radiation heating activation treatment to form porous activated carbon; adjusting the pH value of the product and performing hydrothermal crystallization treatment on the porous activated carbon to obtain molecular sieves; subjecting the remaining residue after acid treatment to plasma-assisted deposition, and performing surface chemical modification and microwave heating regeneration on the activated carbon to obtain highly adsorbent activated carbon. This invention can fully extract metals from gasification slag, and the metal framework in the gasification slag has high support strength; plasma-assisted deposition is used to improve carbon growth; and the activated carbon is modified to improve adsorption performance.

Description

Technical Field

[0001] The invention relates to the field of solid waste resource processing, and in particular to a method for high-value resource utilization of gasified slag. Background Art

[0002] At present, the output of coal gasification slag is large, the utilization rate is low, the processing cost is high and there is an environmental threat. Storage and landfill are still the main disposal methods of coal gasification slag. A large amount of gasification slag has caused great pollution to the ecological environment, but a scientific and reasonable disposal technology system has not yet been formed. For example: the prior art discloses a method for resource utilization of biomass ash, including the following steps: pre-treating biomass ash to obtain primary biomass ash; soaking the primary biomass ash with acid to obtain primary biomass ash; boiling the primary biomass ash with alkali to obtain water glass; filling a part of the water glass with carbon dioxide gas, neutralizing it to a solution pH value of 9 to 11, and then adding a flocculant at a mass ratio of 1:40 to 100 of flocculant to solution to fully flocculate and precipitate, filtering and drying to obtain a solid sample; roasting the solid sample to obtain nano-silicon dioxide; using the remaining water glass and nano-silicon dioxide as silicon sources, together with aluminum sources, deionized water and seeds to synthesize porous ZSM-5 molecular sieves.

[0003] The above scheme makes a porous molecular sieve to improve the efficiency of waste slag treatment and solve the pollution problem. However, the resource utilization of gasification slag in this scheme mainly has the following problems: 1) Silicon dioxide is extracted from gasification slag to prepare molecular sieves. The product performance has high purity and performance, but the metal in the gasification slag cannot be effectively extracted, resulting in metal waste; 2) The gasification slag is comprehensively utilized, treated with alkali solution and carbon dioxide to obtain silicon dioxide, and activated carbon and molecular sieves are subsequently prepared. Carbon can be effectively utilized, and production is environmentally friendly and economical, but the performance of activated carbon is not high. 3) There are also some studies that directly use solid wastes such as coal slag and gas slag to directly make molecular sieves, but the quality of the obtained molecular sieves is not high. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for high-value resource utilization of gasification slag, which can fully extract the metals in the gasification slag and the high metal skeleton supporting strength in the gasification slag; utilize plasma assisted deposition to improve the carbon growth effect; and modify the activated carbon to improve the adsorption performance.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0006] An embodiment of the present invention provides a method for high-value resource utilization of gasified slag, comprising the following steps:

[0007] The gasified slag is acid-dissolved to precipitate metal;

[0008] The solution after acid dissolution is filtered multiple times to extract useful metals;

[0009] The residue after the acid treatment is placed in a microwave oven chamber for radiation heating activation treatment, so that the residue forms activated carbon with a porous structure;

[0010] The pH value of the product is adjusted, and the activated carbon with expanded pores is subjected to hydrothermal crystallization treatment to obtain a molecular sieve;

[0011] The remaining residue after the acid treatment is subjected to plasma assisted deposition, and the activated carbon is subjected to surface chemical modification and microwave heating regeneration to obtain highly adsorbent activated carbon.

[0012] As a further implementation method, dilute hydrochloric acid with a set mass ratio is mixed with the gasified slag for ultrasonic treatment, and then stirred for a set time after the ultrasonic treatment;

[0013] The mixed liquid is filtered and the filter residue is washed until the washing liquid is neutral, and the metal-containing filter liquid is collected and obtained.

[0014] As a further implementation method, a chemical reduction extraction method is adopted, and a reducing agent is added to the filtrate to convert the metal ions into a single substance for precipitation.

[0015] As a further implementation method, the product after alkali activation is acid-washed and filtered to remove excess sodium hydroxide, thereby achieving solid-liquid separation again.

[0016] As a further implementation method, the product is placed in a hydrothermal kettle, and treated under acidic hydrothermal conditions using hydroxide as a precursor to prepare a molecular sieve; and silicon and aluminum in the cleaning liquid are extracted.

[0017] As a further implementation method, the activated carbon is surface treated by chemical modification using polyethyleneimine and urea, and is simultaneously regenerated by microwave heating to reconstruct micropores.

[0018] As a further implementation method, the product after alkali activation is subjected to carbon growth treatment: the product, tar and ethanol with a set mass ratio are mixed, stirred evenly and then subjected to microwave high-temperature treatment. During the heating process, the material surface is bombarded by plasma technology to deposit carbon on the residue surface.

[0019] As a further implementation method, the mass ratio of the product, tar and ethanol is 1:2:1.5, and the product is placed in a magnetic stirrer and stirred for 12 hours; the reaction temperature of the microwave high temperature treatment is 800°C, and the reaction time is 3 hours.

[0020] As a further implementation method, the surface of the activated carbon is modified: polyethyleneimine and urea crystals are dissolved in distilled water, stirred at room temperature for a set time, the solution is heated to a set temperature and maintained in a stirring state; then, the activated carbon is added to the mixed solution and stirred at room temperature for a set time.

[0021] As a further implementation method, the treated sample is washed with deionized water for multiple times and then dried; it is then placed in a microwave vacuum heater, using nitrogen as a carrier gas to remove the adsorbed substances, and the small molecules in the microwave vacuum environment are used to transform the micropores of the activated carbon.

[0022] The beneficial effects of the present invention are as follows:

[0023] (1) The present invention can fully extract the metals in the gasification slag and can fully utilize the carbon skeleton in the gasification slag as the skeleton of the final activated carbon, which contains a large amount of carbon, a small amount of metals and components such as Al and Si, and has a high skeleton support strength.

[0024] (2) The present invention utilizes plasma to bombard the material during activation to enhance the carbon growth effect; since the prepared activated carbon has a high-strength skeleton, the porous activated carbon is not easy to collapse during surface modification; when modifying the activated carbon, a chemical treatment plus microwave regeneration method is utilized to greatly enhance the adsorption performance.

[0025] (3) The present invention prepares a variety of useful substances in steps, such as extracting metals, synthesizing molecular sieves, preparing activated carbon, etc., thus realizing the all-round resource utilization and high-value utilization of gasification slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0027] Figure 1 is a flow chart of the present invention according to one or more embodiments;

[0028] Figure 2 is a schematic diagram of a device structure according to one or more embodiments of the present invention;

[0029] Figure 3 is a scanning electron microscope image of a molecular sieve according to one or more embodiments of the present invention;

[0030] Figure 4 is a scanning electron microscope image of activated carbon according to one or more embodiments of the present invention.

[0031] Among them, 1. solid-liquid separation equipment, 2. microwave heating furnace, 3. drying separation equipment, 4. pickling liquid outlet, 5. gasification slag inlet, 6. acid liquid inlet, 7. waste liquid outlet. DETAILED DESCRIPTION

[0032] Embodiment 1:

[0033] This embodiment provides a method for high-value resource utilization of gasified slag, comprising the following steps:

[0034] The gasified slag is acid-dissolved to precipitate metal;

[0035] The solution after acid dissolution is filtered multiple times to extract useful metals;

[0036] The residue after the acid treatment is placed in a microwave oven chamber for radiation heating activation treatment, so that the residue forms activated carbon with a porous structure;

[0037] The pH value of the product is adjusted, and the activated carbon with expanded pores is subjected to hydrothermal crystallization treatment to obtain a molecular sieve;

[0038] The remaining residue after the acid treatment is subjected to plasma assisted deposition, and the activated carbon is subjected to surface chemical modification and microwave heating regeneration to obtain highly adsorbent activated carbon.

[0039] The high-value resource utilization method of gasified slag in this embodiment adopts the following method: Figure 2 The device shown comprises a solid-liquid separation device 1, a microwave heating furnace 2 and a drying separation device 3 which are connected in sequence.

[0040] Specifically, Figure 1 As shown, the following steps are included:

[0041] Step (1) dissolves the gasified slag with acid to precipitate metals and recover useful metals.

[0042] Further, 0.5-1.5 mol / L hydrochloric acid is selected to mix with the gasified slag for ultrasonic treatment, and the treatment time is 1-3 hours. The power of the ultrasonic generator is 60W, the mass ratio of the gasified slag to the hydrochloric acid is 1:2-10, the reaction temperature is room temperature-80°C, and after the ultrasonic treatment, it is placed in a magnetic stirrer for stirring for 8-12 hours.

[0043] Step (2) The solution is filtered multiple times until the filtrate is neutral, the filtrate is collected, and the metal contained in the solution is detected and extracted to achieve metal recovery. Figure 2 The solid-liquid separation device 1 shown is used to realize solid-liquid separation and solid drying. A pickling liquid outlet 4 is provided on the side of the solid-liquid separation device 1 and a gasified slag inlet 5 is provided on the top.

[0044] The filtrate is then tested and analyzed for the metal elements it contains. A chemical reduction extraction method is used, and a reducing agent is added to convert the metal ions into single substances for precipitation.

[0045] Step (3) performs pore expansion and silicon-aluminum extraction on the acid-treated residue to achieve porosity of the gasified slag particles.

[0046] Furthermore, the residue filtered out in step (1) and the alkali are mechanically ground to make them evenly mixed, and then placed in a microwave oven chamber for radiation heating activation treatment, so that the residue forms activated carbon with a porous structure to achieve pore expansion.

[0047] In this embodiment, the residue after acid treatment is placed in a microwave heating furnace for high-temperature alkali activation to achieve heating at the molecular level; the microwave radiation power is 1000-1500W, the radiation frequency is 2450-2600MHz, the mass ratio of slag to sodium hydroxide is 1:1-4, the heating stage is non-steady-state heating, the reaction temperature is 650-850°C, the holding time is 1.5-3h, and the activated product is obtained. The above process is as follows Figure 2 The microwave heating oven 2 is shown.

[0048] Step (4) Preparation of molecular sieve: The pH value of the product is adjusted, and the activated carbon with pores is subjected to hydrothermal crystallization treatment to obtain a molecular sieve.

[0049] Further, the product after alkali activation is acid-washed and filtered to remove excess sodium hydroxide. Figure 2 The solid-liquid separation is completed in the drying and separation device 3 shown in the figure. The top of the drying and separation device 3 is provided with an acid liquid inlet 6, and the side is connected with a waste liquid outlet 7.

[0050] The product is placed in a hydrothermal kettle, treated under acidic hydrothermal conditions at 100-200°C using hydroxide as a precursor to produce a molecular sieve with good dispersion and a grain size of 10nm-15nm; at the same time, the cleaning solution contains a large amount of Si and part of Al, and the cleaning solution can be extracted to obtain most of the Si and Al.

[0051] Step (5) Surface growth of activated carbon to synthesize high specific surface area and porous activated carbon. Plasma-assisted deposition is performed on the remaining residue in step (2), and the residue is mixed with raw materials such as tar and organic waste liquid, stirred and fully mixed for 12-24 hours, and then heated by microwave at 650-800°C for 1-3 hours, and the material is bombarded with ion beams to attach carbon to the slag surface to form a dense deposition layer, thereby achieving carbon growth and obtaining high specific surface area and porous activated carbon.

[0052] In this embodiment, the product, tar and potassium hydroxide are mixed in a mass ratio of 1:1:2, and placed in a magnetic stirrer for 12 hours to mix them fully. Then, microwave high-temperature treatment is carried out, the reaction temperature is 800°C, and the reaction time is 3 hours. During the heating process, the material is bombarded on the surface by pulse high-energy density plasma technology, and carbon is deposited on the slag surface to form a dense deposition layer to achieve carbon growth. The material is tested by BET and SEM, and a high specific surface area and porous activated carbon is obtained.

[0053] Step (6) Surface modification of activated carbon to significantly improve the adsorption capacity of activated carbon. The activated carbon is surface treated by chemical modification using polyethyleneimine and urea, and is regenerated by microwave heating to reconstruct micropores, thereby significantly improving the adsorption capacity of activated carbon.

[0054] In this embodiment, 3g of polyethyleneimine and 1g of urea crystals were dissolved in 50ml of distilled water, and magnetically stirred at room temperature for 1h, then the solution was heated to 100°C and stirred for 1.5h, and then activated carbon was added to the mixed solution and stirred at room temperature for 72h. The treated sample was washed with deionized water several times, placed in an oven and dried at 120°C for 10h, and then placed in a microwave vacuum heater, with N2 as the carrier gas and a microwave radiation power of 800W. The adsorbed substances were removed by a microwave vacuum heating device, and small molecules such as N2 or water vapor in the system under a microwave vacuum environment were used to modify the micropores of the activated carbon to achieve the modification of the activated carbon.

[0055] Afterwards, a hydrogen adsorption experiment was carried out on the modified activated carbon: the adsorption pressure was 0-70 bar, the adsorption temperature was room temperature, the adsorption gas was pure H2 (99.999%), and the adsorption time was 12 h.

[0056] In this embodiment, metals such as Mg and Fe can be extracted after acid dissolution, and the metals in the gasified slag can be recovered; most of the Si and part of the Al in the slag can be dissolved and extracted through alkali activation; the remaining slag contains a large amount of carbon, a small amount of metals and components such as Al and Si, which can be used as a high-strength support skeleton. At the same time, the dissolution of Si and Al realizes the porosity of the slag; through liquid phase deposition, a high specific surface area and porous activated carbon is generated; after the activated carbon is modified, the adsorption capacity is effectively improved. Under laboratory conditions, the adsorption test shows that the adsorption value can reach 40cm3 / g STP.

[0057] Embodiment 2:

[0058] A certain amount of gasified slag was soaked in deionized water (solid-liquid ratio 1:5) for 1 h, then filtered and dried to obtain about 10.5 g of slag;

[0059] The dried gasified slag was mixed with 1.0 mol / L hydrochloric acid at a mass ratio of 1:10, reacted at 80°C for 4 hours, filtered, washed, and dried to obtain acid-washed slag and acid waste liquid (the acid liquid contained washed metal ions);

[0060] The pickled slag was mixed with potassium hydroxide in a mass ratio of 1:3, and placed in a microwave oven for high-temperature alkali activation at a reaction temperature of 850°C and a reaction time of 2 h to preliminarily obtain a carbon material;

[0061] The product was placed in a hydrothermal reactor, treated under acidic hydrothermal conditions at 150°C using hydroxide as a precursor to produce a molecular sieve with good dispersion and a grain size of 10nm-15nm; the scanning electron microscope image of the molecular sieve is shown in Figure 3 As shown; the pore structure data is shown in Table 1.

[0062] Table 1

[0063]

[0064] In Table 1: SBET is the total specific surface area measured by the BET method, Smic is the micropore specific surface area, Sexter is the external specific surface area, Vtotal is the total pore volume, Vmic is the micropore volume, and Vmeso is the mesopore volume.

[0065] Embodiment three:

[0066] The product, tar and potassium hydroxide were mixed in a mass ratio of 1:1:2, placed in a magnetic stirrer and stirred for 12 hours, and dried and ground to obtain fine slag;

[0067] The fine slag was subjected to microwave high temperature treatment, the reaction temperature was 800°C, and the reaction time was 3h;

[0068] During the heating process, pulsed high energy density plasma technology is used to bombard the material surface and deposit carbon on the slag surface, resulting in high specific surface area and porous activated carbon. The scanning electron microscope image of activated carbon is shown in the figure below. Figure 4 shown.

[0069] Embodiment 4:

[0070] Dissolve 3 g of polyethyleneimine and 1 g of urea crystals in 50 ml of distilled water, stir magnetically at room temperature for 1 h, then heat the solution to 100 °C and stir for 1.5 h, numbered 1;

[0071] Activated carbon was added to the mixed solution and stirred at room temperature for 72 hours. The treated sample was washed with deionized water several times and then dried in an oven at 120°C for 10 hours;

[0072] The treated samples were placed in a microwave vacuum heater, with N2 as carrier gas and microwave radiation power of 800W. The adsorbed substances were removed by a microwave vacuum heating device, and the N2 in the system under a microwave vacuum environment was used to modify the micropores of the activated carbon to achieve modification.

[0073] Dissolve 3g polyethyleneimine and 2g urea crystals in 50ml distilled water, number them 2 and 3 respectively, and the rest of the treatment is the same as 1;

[0074] The modified activated carbon was subjected to hydrogen adsorption experiments: the adsorption pressure was 0-70 bar, the adsorption temperature was room temperature, the adsorption gas was pure H2 (99.999%), and the adsorption time was 12 h;

[0075] The xylene adsorption experiment was carried out on the activated carbon: the air flow rate was 400 mL / min, the adsorption time was 2 h, and the adsorption temperature was room temperature;

[0076] The hydrogen adsorption experiment is shown in Table 2; the xylene adsorption experiment is shown in Table 3.

[0077] Table 2

[0078] Gas / H2 Adsorption pressure Adsorption temperature Adsorption time Adsorption 1 0-70bar Room temperature 12h <![CDATA[40cm3 / g STP]]> 2 0-70bar Room temperature 12h <![CDATA[34cm3 / g STP]]> 3 0-70bar Room temperature 12h <![CDATA[25cm3 / g STP]]>

[0079] Table 3

[0080] Gas / Xylene Penetration time Adsorption temperature Adsorption time Adsorption 1 10min Room temperature 2h 200mg / g 2 8min Room temperature 2h 182mg / g 3 7min Room temperature 2h 170mg / g

[0081] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for high-value resource utilization of gasified slag, characterized in that: The following steps are involved: Step (1) acid dissolving the gasified slag, selecting 0.5-1.5 mol / L hydrochloric acid and mixing it with the gasified slag for ultrasonic treatment, the treatment time is 1-3 hours, and after ultrasonic treatment, the mixture is placed in a magnetic stirrer and stirred for 8-12 hours. Step (2) The solution is filtered multiple times until the filtrate is neutral, the filtrate is collected, the metal contained in the solution is detected and extracted, the metal is recovered, the solid-liquid separation is achieved in a solid-liquid separation device, and the solid is dried, and then the filtrate is detected and analyzed for the metal elements contained therein, and a chemical reduction extraction method is adopted, and a reducing agent is added to convert the metal ions into a single substance for precipitation. Step (3) expanding the pores of the acid-treated residue to realize the porous nature of the gasified slag particles, mechanically grinding the residue filtered out in step (2) and the alkali to make them uniformly mixed, placing them in a microwave oven chamber for radiation heating activation treatment to form activated carbon with a porous structure of the residue to achieve pore expansion, placing the acid-treated residue in a microwave oven for high-temperature alkali activation to achieve heating at the molecular level; the microwave radiation power is 1000-1500W, the radiation frequency is 2450-2600MHz, the mass ratio of slag to sodium hydroxide is 1:1-4, the heating stage is non-steady-state heating, the reaction temperature is 650-850°C, the holding time is 1.5-3h, and the activated product is obtained. Step (4) acid-washing and suction-filtering the product after alkali activation to remove excess sodium hydroxide, completing the solid-liquid separation in a drying and separation device, placing the product in a hydrothermal kettle, using hydroxide as a precursor, and treating it under acidic hydrothermal conditions at 100-200° C. to prepare a molecular sieve with good dispersion and a grain size of 10nm-15nm; at the same time, the washing solution contains a large amount of Si and part of Al, and the washing solution can be extracted to obtain most of Si and Al. Step (5) Activated carbon surface growth, synthesizing high specific surface area, porous activated carbon, plasma-assisted deposition of the remaining residue in step (4), the product, tar and potassium hydroxide are mixed in a mass ratio of 1:1:2, placed in a magnetic stirrer and stirred for 12 hours to make them fully mixed, and then subjected to microwave high-temperature treatment, the reaction temperature is 800°C, the reaction time is 3 hours, during the heating process, the material is bombarded on the surface by pulse high energy density plasma technology, carbon is deposited on the slag surface, forming a dense deposition layer, and achieving long carbon, Step (6) 3 g of polyethyleneimine and 1 g of urea crystals are dissolved in 50 ml of distilled water, and magnetically stirred at room temperature for 1 hour. The solution is then heated to 100° C. and stirred for 1.5 hours. Activated carbon is then added to the mixed solution and stirred at room temperature for 72 hours. The treated sample is washed with deionized water for multiple times, placed in an oven and dried at 120° C. for 10 hours, and then placed in a microwave vacuum heater with N2 as carrier gas and a microwave radiation power of 800 W. The adsorbed substances are removed by a microwave vacuum heating device, and the activated carbon is modified by using small molecules of N2 or water vapor in the system under a microwave vacuum environment to achieve modified activated carbon.

Images