Quality-divided gradient comprehensive utilization method for coal gasification ash solid waste

Abstract

The invention relates to the technical field of comprehensive utilization of coal gasification ash, and discloses a coal gasification ash solid waste quality-divided gradient comprehensive utilization method which comprises the following steps: dividing ash into coarse slag and fine slag; performing physical separation on the fine slag to obtain a fine slag filter cake with the carbon content of 5-70%, first low-carbon ash slag with the carbon content of less than or equal to 5% and carbon-rich ash slag with the carbon content of more than or equal to 70%; forming the fine slag filter cake into second low-carbon ash slag by utilizing a fine slag decarburization technology; adding a binder into the carbon-rich ash residue, and gasifying for utilization to obtain third low-carbon ash residue and coal gas; preparing polyaluminum chloride and the like from the high-aluminum ash with Al2O3 greater than or equal to 20% in the low-carbon ash; preparing a water glass agent from the high-silicon ash slag with SiO2 greater than or equal to 40%; preparing a coal-based solid waste cementing material or a coal-based solid waste filling material from the low-silicon aluminum ash residue containing less than 40% of SiO2 and less than 20% of Al2O3 and coal gangue or fly ash; the ash utilization method is simple, the comprehensive utilization rate is high, the coal gasification ash can be treated on a large scale, the ecological environment is protected, and the value of the coal gasification ash can be fully utilized.

Description

Technical Field

[0001] The invention relates to the technical field of comprehensive utilization of coal gasification ash, and in particular to a method for comprehensive utilization of coal gasification ash solid waste by quality separation and cascade. Background Art

[0002] Coal gasification technology refers to the process of converting coal into synthesis gas through a series of chemical reactions between coal and gasifying agents. It is an important industry in modern coal chemical technology because of its characteristics of maximizing resource utilization and minimizing pollutant emissions. However, a large amount of coal gasification ash is produced during the coal gasification process. The large-scale emission of ash not only occupies a large amount of land, but also causes soil and water pollution, causing serious impacts on the environment. Therefore, the resource utilization of coal gasification ash is an urgent need for the high-quality development of the ecological environment.

[0003] In the field of coal gasification technology, fly ash obtained from the cyclone separator during the coal gasification process and the filter cake obtained from the washing system are often classified as fine slag, and the large-particle ash obtained from the slag lock bucket during the coal gasification process is classified as coarse slag.

[0004] At present, the application of coal gasification ash at home and abroad is mainly concentrated in the following aspects: ① Building materials: cementitious materials, aggregates, concrete, wall materials and unburned bricks, etc.; ② Soil and water body remediation: soil improvement, adsorption materials for water body remediation, etc.; ③ Utilization of residual carbon: residual carbon properties, cyclic blending, residual carbon quality improvement, etc.; ④ Preparation of high value-added materials: rubber and plastic fillers, catalyst carriers, silicon-based materials, ceramic materials, etc. However, the amount of coal gasification ash produced has remained high, but the comprehensive utilization rate of resources is low, which shows that although some technologies and projects are trying to improve the utilization rate of coal gasification ash, there is still a lot of room for improvement overall, which seriously restricts the development of the modern coal chemical industry. Summary of the invention

[0005] The present invention proposes a method for the cascade comprehensive utilization of coal gasification ash solid waste by quality separation to solve the deficiencies in the above-mentioned prior art. The method for the cascade comprehensive utilization of coal gasification ash solid waste by quality separation improves the utilization value of coal gasification ash and reduces the impact on the environment. It can realize large-scale disposal of coal gasification ash, protect the ecological environment, and fully utilize the value of coal gasification ash.

[0006] The technical solution of the present invention is: a method for comprehensive utilization of coal gasification ash solid waste by quality classification, comprising:

[0007] S1: Separate the coal gasification ash into coarse ash and fine slag; the fine slag is the fly ash obtained from the cyclone separator during the coal gasification process and the filter cake obtained from the washing system, and the coarse slag is the large-particle ash obtained in the slag discharge lock bucket during the coal gasification process.

[0008] S2: Physically sorting the fine slag to obtain a fine slag filter cake with a carbon content of 5% to 70%, a first low-carbon ash with a carbon content of ≤5%, and a carbon-rich ash with a carbon content of ≥70%;

[0009] S3, using the fine slag filter cake to form a second low-carbon ash slag with a carbon content of ≤5% by using the fine slag decarbonization technology; adding a binder to the carbon-rich ash slag to form a carbon-rich slag, and re-gasifying and utilizing it by gasification technology to obtain a third low-carbon ash slag with a carbon content of ≤5% and coal gas;

[0010] S4. The high-alumina ash with Al2O3≥20% in the first low-carbon ash, the second low-carbon ash and the third low-carbon ash is used to prepare polyaluminium chloride, alumina or aluminium hydroxide; the high-silicon ash with SiO2≥40% is used to prepare water glass, silicon carbide or rubber filler; the low-silicon-alumina ash with SiO2<40% and Al2O3<20% is combined with coal gangue or fly ash to prepare coal-based solid waste cementitious materials or coal-based solid waste filling materials.

[0011] In at least one embodiment of the present invention, in step S2, the physical separation method is to separate the carbon ash in the coal gasification ash by using a spiral separator, a screening machine or a flotation machine.

[0012] In at least one embodiment of the present invention, in step S3, the fine slag decarburization technology refers to preheating decarburization technology or pyrolysis combustion decarburization, which utilizes the residual carbon in the fine slag to rapidly undergo an oxidation reaction, so that the fine slag filter cake is converted into a second low-carbon ash.

[0013] In at least one embodiment of the present invention, in step S3, the carbon-rich ash can be combined with coal for reuse.

[0014] In at least one embodiment of the present invention, in step S4, the high-aluminum ash, high-silicon ash and low-silicon-aluminum ash are distinguished by using an X-ray fluorescence spectrometer to test the Al2O3 and SiO2 contents in the first low-carbon ash, the second low-carbon ash and the third low-carbon ash, and then distinguishing the types of the first low-carbon ash, the second low-carbon ash and the third low-carbon ash.

[0015] In at least one embodiment of the present invention, in step S4, the coarse slag separated in step S1 is directly tested by an X-ray fluorescence spectrometer to identify the type of the coarse slag among high-aluminum ash slag, high-silicon ash slag and low-silicon-aluminum ash slag.

[0016] In at least one embodiment of the present invention, in step S4, the coal-based solid waste cementitious material refers to a material that is made from byproducts of coal mining, processing, combustion and conversion processes and is capable of cementing other materials.

[0017] In at least one embodiment of the present invention, in step S4, the coal-based solid waste filling material refers to a material with a certain strength prepared by a mine in order to treat solid waste or mine coal resources under buildings, water bodies, and roads, and to control surface subsidence and rock movement.

[0018] In at least one embodiment of the present invention, the fine slag is fly ash obtained from the cyclone separator during coal gasification and filter cake obtained from the washing system, and the coarse slag is large-particle ash obtained from the slag discharge lock bucket during coal gasification, which is low-carbon ash.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The method for comprehensive utilization of coal gasification ash by quality classification and tiered steps proposed in the present invention can extract and recover a large amount of valuable elements such as silicon and aluminum contained in the coal gasification ash, and convert it into chemical raw materials such as aluminum chloride, aluminum oxide, aluminum hydroxide, water glass, silicon carbide or rubber filler, as well as building materials such as coal-based solid waste cementitious materials or coal-based solid waste filling materials. The conversion of these high value-added products improves the efficiency of resource utilization, reduces resource waste, promotes the development of circular economy, and realizes efficient and circular utilization of resources.

[0021] 2. The present invention can promote the reduction, resource utilization, high-value and green disposal of coal gasification ash, innovate the industrial model of resource utilization and green and efficient filling and disposal of coal gasification ash, and effectively support the synergistic efficiency improvement and green development of pollution reduction and carbon reduction in the coal chemical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure is a flow chart of the quality separation and utilization of the present invention. DETAILED DESCRIPTION

[0023] The drawings in the present invention are not drawn strictly according to the actual scale, and the specific size and quantity of each structure can be determined according to actual needs. The drawings described in the present invention are only schematic diagrams of the structures.

[0024] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. The words "include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Inside", "outside", "up", "down", "far", "near", "front", "back" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0026] At present, the application of coal gasification ash at home and abroad is mainly concentrated in the following aspects: ① Building materials: cementitious materials, aggregates, concrete, wall materials and unburned bricks, etc.; ② Soil and water body remediation: soil improvement, adsorption materials for water body remediation, etc.; ③ Utilization of residual carbon: residual carbon properties, cyclic blending, residual carbon quality improvement, etc.; ④ Preparation of high value-added materials: rubber and plastic fillers, catalyst carriers, silicon-based materials, ceramic materials, etc. The amount of coal gasification ash produced has remained high, but the comprehensive utilization rate of resources is only 31.6%. This shows that although some technologies and projects are trying to improve the utilization rate of coal gasification ash, there is still a lot of room for improvement overall, which seriously restricts the development of the modern coal chemical industry.

[0027] In view of the problems of low comprehensive utilization rate of coal gasification ash and difficulty in large-scale disposal, the present invention proposes a method for the comprehensive utilization of coal gasification ash by quality classification and tiered steps, which fully considers the physical properties (particle size) and chemical composition (content of oxides such as aluminum and silicon, and carbon content) of the coal gasification slag, realizes the comprehensive utilization of the coal gasification slag by quality classification and tiered steps, improves the utilization value of the coal gasification ash, reduces the impact on the environment, can realize large-scale disposal of the coal gasification ash, protect the ecological environment, and can fully utilize the value of the coal gasification ash.

[0028] Combination Figure 1 As shown, a method for comprehensive utilization of coal gasification ash solid waste by quality classification and cascade, comprising:

[0029] S1: The coal gasification ash is divided into coarse slag and fine slag; the fine slag is the fly ash obtained from the cyclone separator during the coal gasification process and the filter cake obtained from the washing system, and the coarse slag is the large-particle ash obtained from the slag lock bucket during the coal gasification process; the definition and distinction of coarse slag and fine slag is based on the different ways of obtaining them during the coal gasification process, which belongs to the basic knowledge of this subject.

[0030] S2: Physically sorting the fine slag to obtain a fine slag filter cake with a carbon content of 5% to 70%, a first low-carbon ash with a carbon content of ≤5%, and a carbon-rich ash with a carbon content of ≥70%;

[0031] S3, using the fine slag filter cake to form a second low-carbon ash slag with a carbon content of ≤5% by using the fine slag decarbonization technology; adding a binder to the carbon-rich ash slag to form a carbon-rich slag, and re-gasifying and utilizing it by gasification technology to obtain a third low-carbon ash slag with a carbon content of ≤5% and coal gas;

[0032] S4. The high-aluminum ash with Al2O3≥20% in the first low-carbon ash, the second low-carbon ash and the third low-carbon ash is used to prepare polyaluminum chloride, aluminum oxide or aluminum hydroxide; the high-silicon ash with SiO2≥40% is used to prepare water glass, silicon carbide or rubber filler; the low-silicon-aluminum ash with SiO2<40% and Al2O3<20% is combined with coal gangue or fly ash to prepare coal-based solid waste cementitious materials or coal-based solid waste filling materials. This method for utilizing coal gasification ash is simple and has a high comprehensive utilization rate. It can not only dispose of coal gasification ash on a large scale and protect the ecological environment, but also make full use of the value of coal gasification ash.

[0033] As an alternative embodiment, the physical separation method is to separate the carbon ash in the coal gasification ash by using physical separation equipment such as a spiral separator, a screening machine or a flotation machine.

[0034] As an alternative embodiment, in step S3, the fine slag decarbonization technology refers to preheating decarbonization technology or pyrolysis decarbonization, which utilizes the residual carbon in the fine slag to rapidly undergo an oxidation reaction, so that the fine slag filter cake is converted into a second low-carbon ash.

[0035] As an alternative embodiment, in step S4, the carbon-rich slag is a gasification raw material with high activity and large particle size formed by adding a binder to the carbon-rich ash slag.

[0036] As an alternative embodiment, in step S3, the carbon-rich ash can be reused in combination with coal; adding a binder to the carbon-rich ash to form a carbon-rich slag and gasifying it for utilization and reusing the carbon-rich ash in combination with coal are two parallel solutions, which can be selected according to the actual needs of the factory.

[0037] As an alternative embodiment, in step S4, the high-aluminum ash, high-silicon ash and low-silicon-aluminum ash are distinguished by using an X-ray fluorescence spectrometer to test the Al2O3 and SiO2 contents in the first low-carbon ash, the second low-carbon ash and the third low-carbon ash, and then distinguishing the types of the first low-carbon ash, the second low-carbon ash and the third low-carbon ash.

[0038] As an alternative embodiment, in step S4, the coarse slag separated in step S1 is directly tested by using an X-ray fluorescence spectrometer to identify the type of the coarse slag among high-aluminum ash slag, high-silicon ash slag and low-silicon-aluminum ash slag.

[0039] As an alternative embodiment, in step S4, the coal-based solid waste cementitious material refers to a composite solid material that can be cemented with other materials to form a certain strength, similar to cement, and can be used to prepare building materials such as concrete and mortar.

[0040] As an alternative embodiment, in step S4, the coal-based solid waste filling material refers to a material with a certain strength prepared by a mine in order to treat solid waste or mine coal resources under buildings, water bodies, and roads, and to control surface subsidence and rock movement.

[0041] Practical application cases of the present invention:

[0042] 1. The plant discharges 600,000 tons of coal gasification ash annually, including 400,000 tons of coarse ash and 200,000 tons of fine ash. The fine ash is separated into 50,000 tons of carbon-rich ash, 50,000 tons of fine ash filter cake and 100,000 tons of low-carbon ash by flotation.

[0043] 2. The fine slag filter cake is decarbonized by preheating decarbonization technology, so that the carbon content of the ash after decarbonization is ≤5%, and 40,000 tons of low-carbon ash is prepared.

[0044] 3. Adding binder to 10,000 tons of carbon-rich ash to form carbon-rich slag, through gasification reaction, 3,500 tons of low-carbon ash and 2,000 cubic meters of coal gas were produced. Another 40,000 tons of carbon-rich ash was mixed with coal for reuse.

[0045] 4. 40,000 tons of fly ash, sodium carbonate, water glass and other substances were added to the 60,000 tons of low-carbon ash to prepare 100,000 tons of coal-based solid waste gel material.

[0046] 5. 1.1 million tons of coal gangue produced by a coal mine, 32 tons of water and 100,000 tons of coal-based solid waste gel materials were added to 480,000 tons of low-carbon ash with low aluminum and silicon content (SiO2 < 40%, Al2O3 < 20%), and 2 million tons of coal-based solid waste filling materials were obtained. All of them were filled into the mining space generated by the mine, replacing 1.3 million tons of coal resources under buildings (structures), controlling surface subsidence and protecting the ground ecological environment.

[0047] The above embodiments are only specific implementation methods of the patent of the present invention, which are used to illustrate the technical solution of the patent of the present invention rather than to limit it. The protection scope of the patent of the present invention is not limited thereto. Although the patent of the present invention is described in detail with reference to the above embodiments, ordinary technicians in this field should understand that any technician familiar with the technical field can still modify the technical solution recorded in the above embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solution for implementing the patent of the present invention, and should be covered within the protection scope of the present invention.

Claims

1. A method for comprehensive utilization of coal gasification ash solid waste by quality classification and cascade, characterized in that: The following steps are involved: S1: Separating coal gasification ash into coarse slag and fine slag; S2: Physically sorting the fine slag to obtain a fine slag filter cake with a carbon content of 5% to 70%, a first low-carbon ash with a carbon content of ≤5%, and a carbon-rich ash with a carbon content of ≥70%; S3, using the fine slag filter cake to form a second low-carbon ash slag with a carbon content of ≤5% by using the fine slag decarbonization technology; adding a binder to the carbon-rich ash slag to form a carbon-rich slag, and re-gasifying and utilizing it by gasification technology to obtain a third low-carbon ash slag with a carbon content of ≤5% and coal gas; S4. The high-alumina ash with Al2O3≥20% in the first low-carbon ash, the second low-carbon ash and the third low-carbon ash is used to prepare polyaluminium chloride, alumina or aluminium hydroxide; the high-silicon ash with SiO2≥40% is used to prepare water glass, silicon carbide or rubber filler; the low-silicon-alumina ash with SiO2<40% and Al2O3<20% is combined with coal gangue or fly ash to prepare coal-based solid waste cementitious materials or coal-based solid waste filling materials.

2. A method for comprehensive utilization of coal gasification ash solid waste by quality classification as claimed in claim 1, characterized in that: In step S2, the physical separation method refers to separating the fine slag using a spiral separator, a screening machine or a flotation machine.

3. A method for comprehensive utilization of coal gasification ash solid waste by quality classification as claimed in claim 1, characterized in that: In step S3, the fine slag decarbonization technology refers to preheating decarbonization technology or pyrolysis combustion decarbonization, which utilizes the residual carbon in the fine slag to rapidly undergo an oxidation reaction, so that the fine slag filter cake is converted into a second low-carbon ash.

4. The method for comprehensive utilization of coal gasification ash solid waste by quality classification as claimed in claim 1, characterized in that: In step S3, the carbon-rich ash can be combined with coal for reuse.

5. The method for comprehensive utilization of coal gasification ash solid waste by quality classification as claimed in claim 1, characterized in that: In step S4, the high-aluminum ash, high-silicon ash and low-silicon-aluminum ash are distinguished by using an X-ray fluorescence spectrometer to test the Al2O3 and SiO2 contents in the first low-carbon ash, the second low-carbon ash and the third low-carbon ash, and then distinguishing the types of the first low-carbon ash, the second low-carbon ash and the third low-carbon ash.

6. The method for comprehensive utilization of coal gasification ash solid waste by quality classification as claimed in claim 1, characterized in that: In step S4, the coarse slag separated in step S1 is directly tested by using an X-ray fluorescence spectrometer to identify the type of the coarse slag among high-aluminum ash slag, high-silicon ash slag and low-silicon-aluminum ash slag.

7. The method for comprehensive utilization of coal gasification ash solid waste by quality classification as claimed in claim 1, characterized in that: In step S4, the coal-based solid waste cementitious material is used to cement building aggregates to form solid buildings, and the coal-based solid waste filling material is used to fill mines to control surface subsidence and rock movement.

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