A process for utilizing coal gasification slag in different grades and qualities

Abstract

The present invention discloses a grading and quality-based utilization process of coal gasification slag, which belongs to the field of solid waste resource utilization. The process includes the following steps: a. screening of coarse coal gasification slag and high-pressure roller grinding; b. mixing, drying and grading of materials; c. iron removal of low-carbon materials; d. continuous segmented grinding of iron-removed materials. The process obtains carbon-rich materials, iron-rich materials and materials with a specific surface area of ​​≥550m through high-pressure roller grinding, drying and grading, high-efficiency iron removal and continuous segmented grinding. 2 / kg, volcanic ash admixture with 28d activity index ≥75%, can realize graded and quality-based utilization of coarse and fine slag from coal gasification; the obtained carbon-rich particles can be used as a co-burning fuel to provide hot air for the drying process of coal gasification slag, and the iron-rich minerals can be sold as iron correctors or low-grade iron concentrates in the cement industry; the volcanic ash admixture can be used as a mixing material for silicate cement or concrete.

Description

Technical Field

[0001] The invention belongs to the field of solid waste resource utilization, and specifically relates to a process for grading and quality-based utilization of coal gasification slag. Background Art

[0002] In recent years, the rapid development and application of coal gasification technology has provided a good guarantee for the efficient and clean utilization of coal in my country. However, due to the influence of coal gasification process and coal quality, the complete conversion of coal cannot be achieved during the coal gasification process. After the inorganic minerals and unburned carbon residues in the coal are oxidized by the high temperature of the gasifier, a large amount of coal gasification slag is generated. According to the different locations of generation, coal gasification slag can be divided into two categories: coarse slag and fine slag. Among them, coarse slag is discharged from the bottom slag outlet after rapid cooling from the molten state, generally accounting for 60% to 80% of the slag discharge; fine slag is mainly produced in the dust removal device of synthesis gas, accounting for 20% to 40% of the slag discharge. At present, the emission of coal gasification slag in my country shows a significant growth trend. According to statistics, the annual emission of coal gasification slag in my country has reached more than 50 million tons in recent years. However, the comprehensive utilization rate of coal gasification slag is less than 10%, and most of the coal gasification slag is still disposed of by stacking and landfilling, which has high treatment costs and occupies a large amount of land. The dust and leaching water generated also pose a serious threat to the environment and human survival safety.

[0003] The bulk disposal and resource utilization of coal gasification slag has become the focus of domestic and foreign scholars in recent years. The Chinese invention patent with publication number CN 106800416A discloses a method for preparing low creep refractory bricks using coal gasification slag. The method uses fluidized bed coal gasification slag, cordierite, zirconium corundum, limestone, fly ash and feldspar as the main raw materials, adds boron carbide fiber and nano tungsten oxide and other additives to prepare raw materials, and adopts fine grinding-microwave high temperature sintering-washing-drying and other processes to prepare refractory materials with high mechanical properties, low creep and good seismic performance. The Chinese invention patent with publication number CN104774023A provides a method for preparing lightweight ceramsite using coal gasification slag, fly ash and potassium feldspar as the main raw materials. The method makes good use of the residual carbon and siliceous components in the coal gasification slag. The Chinese invention patent with publication number CN105130487A proposes a method for preparing filter ceramics using fly ash and coal gasification slag as raw materials through grinding, molding and sintering processes. The Chinese invention patent with publication number CN110720371A discloses a method for regreening sandy land using coal gasification solid slag. The method points out that the advantage of the large specific surface area of ​​coal gasification slag can be utilized to combine coal gasification slag with microbial fertilizer to improve sandy soil, and to plant alfalfa to achieve sandy land regreening. The Chinese invention patent with publication number CN115611684A discloses a method for preparing silicon fertilizer using coal gasification slag based on the high content of silicon minerals in coal gasification slag. The specific process of this method includes processes such as coal gasification slag drying, crushing, screening, acid dissolution, solid-liquid separation and roasting, and silicon fertilizer can be produced. Based on the high carbon content of coal gasification slag, the Chinese invention patent with publication number CN102980195A discloses a method for treating coal chemical gasification slag, wherein the gasification slag is evenly mixed with coal slime and then white mud slurry is added, and the mixture is sent to a fluidized bed boiler through a conveying pipeline for combustion to improve the utilization efficiency of the carbon therein. The Chinese invention patent with publication number CN107857496A discloses a method for preparing an adsorbent material using coal gasification fine slag, comprising adding water to prepare a coal gasification fine slag slurry and stirring and separating the slurry, collecting the heavy separation product to obtain a silicon-rich composite slurry, collecting the light separation product to obtain a carbon-rich composite slurry, and then performing solid-liquid separation and drying on the carbon-rich composite slurry to obtain a carbon-rich adsorbent material.

[0004] The above studies show that the resource utilization of coal gasification slag mainly focuses on the utilization of building materials, soil remediation, water improvement, and high-value utilization of residual carbon and siliceous minerals. However, due to the influence of coal quality, type of solvent and gasification process, the chemical composition and residual carbon content of different types of coal gasification slag vary greatly, which greatly limits its resource utilization. In addition, the existing process methods are generally based on the treatment and resource utilization of a single component in the coal gasification slag, and secondary pollution may still occur during the utilization process. Summary of the invention

[0005] Based on the above technical problems, the present invention proposes a process for graded and quality-based utilization of coal gasification slag.

[0006] The technical solution adopted by the present invention is:

[0007] A process for utilizing coal gasification slag in a graded and quality-based manner comprises the following steps:

[0008] a. Coal gasification coarse slag screening and high pressure roller grinding;

[0009] After being weighed by the first belt scale, the crude slag from coal gasification is evenly fed into the grading screen. After being screened by the grading screen, the coarse particles on the screen enter the high-pressure roller mill for roller crushing, and the fine particles under the screen are discharged from the discharge port at the bottom of the grading screen to the conveyor belt; the materials after roller crushing by the high-pressure roller mill also fall into the conveyor belt;

[0010] b. Mixing, drying and grading of materials;

[0011] After being weighed by the second belt scale, the coal gasification fine slag directly enters the conveyor belt, and is transported by the conveyor belt. The coal gasification fine slag, the fine particles under the screen in step a, and the materials crushed by the high-pressure roller mill enter the drying kiln together, and are dehydrated and mixed in the drying kiln to obtain a dry mixed material;

[0012] The dried mixed material enters the first airflow classifier for sorting, and obtains low-carbon and carbon-rich materials respectively; the carbon-rich material enters the first cyclone separator through the discharge pipe at the top of the first airflow classifier for collection; the low-carbon material enters the temporary storage bin for storage;

[0013] c. Removal of iron from low carbon materials;

[0014] The low-carbon materials stored in the temporary storage bin are fed into the vibrating feeder through the first screw conveyor at the bottom to ensure that the low-carbon materials are evenly fed into the permanent magnetic dry separator for iron removal. After the low-carbon materials are separated by the permanent magnetic dry separator, iron-removed materials and iron-rich materials are obtained.

[0015] d. Continuous segmented grinding of iron removal materials;

[0016] The iron-removed materials are fed into the ball mill for grinding, and the discharged ground materials are blown to the second air classifier through the Roots blower. After the ground materials are classified by the second air classifier, the materials with specific surface area reaching the set value are collected by the second cyclone separator as the final product; the materials with specific surface area not reaching the set value are returned to the ball mill for further grinding;

[0017] The materials collected by the second cyclone separator are transported to the finished product warehouse through the second screw conveyor and bucket elevator.

[0018] Preferably, in step a: the mesh size of the grading sieve is 4 to 6 mm.

[0019] Preferably, in step b: the hot air temperature in the drying kiln is controlled at 300-400° C., and the rotation speed of the drying kiln is 4-8 r / min.

[0020] Preferably, the mass ratio of coal gasification fine slag to coal gasification coarse slag is controlled to be 1:3 to 1:9.

[0021] Preferably, in step b: the particle size of the carbon-rich material is less than 45 μm, the carbon content of the carbon-rich material is controlled to be more than 30%, and the carbon-rich material is mixed with other fuels to generate hot air for drying the mixed material;

[0022] The particle size of low-carbon materials is greater than 45 μm, and their main chemical composition is SiO2, Al2O3 and Fe2O3, and the carbon content is controlled below 3%;

[0023] In the mixed material sorting process, by adjusting the process parameters of the first airflow classifier, including the rotation speed and air volume, the yield of low-carbon and carbon-rich materials can be regulated.

[0024] Preferably, in step c: the permanent magnetic dry magnetic separator is arranged in three levels: upper, middle and lower, and includes, from top to bottom, a first-level magnetic roller, a second-level magnetic roller and a third-level magnetic roller, the magnetic induction intensity of the first-level magnetic roller is 3000Gs, the magnetic induction intensity of the second-level magnetic roller is 5000Gs, and the magnetic induction intensity of the third-level magnetic roller is 8000Gs; the roller speed of the permanent magnetic dry magnetic separator is controlled at 20-60r / min.

[0025] Preferably, in step c: the obtained iron-rich material has an iron grade of 15-45%, and can be sold as low-grade iron concentrate or cement iron corrector.

[0026] Preferably, in step d: the ball mill includes a first-stage ball mill, a second-stage ball mill and a third-stage ball mill; the de-ironing material is first fed into the third belt scale, and then the de-ironing material is transported to the first-stage ball mill for grinding; the de-ironing material is ground in the first-stage ball mill and then enters the fourth belt scale, and then the de-ironing material is transported by the fourth belt scale to the second-stage ball mill for grinding; the de-ironing material is ground in the second-stage ball mill and then enters the fifth belt scale, and then the de-ironing material is transported by the fifth belt scale to the third-stage ball mill for grinding.

[0027] Preferably, a first spray device is provided above the third belt scale, a second spray device is provided above the fourth belt scale, and a third spray device is provided above the fifth belt scale, and the first spray device, the second spray device and the third spray device are all connected to the grinding aid storage tank through a pipeline;

[0028] Among them, the grinding aid added by the first spray device is 0.3‰~0.5‰ of the mass of the material entering the first stage ball mill; the grinding aid added by the second spray device is 0.2‰~0.3‰ of the mass of the material entering the second stage ball mill; the grinding aid added by the third spray device is 0.1‰~0.2‰ of the mass of the material entering the third stage ball mill.

[0029] Preferably, in step d: the set value is 550m 2 / kg, the materials whose specific surface area does not reach the set value are returned to the three-stage ball mill for further grinding; the final product obtained in the finished product warehouse is a volcanic ash mixture, which can be used as a mixing material for silicate cement or concrete.

[0030] The beneficial technical effects of the present invention are as follows:

[0031] (1) The present invention proposes a process for the classification and quality utilization of coal gasification slag, which obtains carbon-rich material, iron-rich material and slag with a specific surface area of ​​≥550m through high-pressure roller grinding, drying and classification, high-efficiency iron removal and continuous segmented grinding. 2 / kg, 28d activity index ≥75% of volcanic ash mixed material, to achieve the graded and quality-based utilization of gasification coarse slag and fine slag. The obtained carbon-rich particles can be used as a blended fuel to provide hot air for the drying process of gasification slag, and the iron-rich minerals can be sold as iron correctors or low-grade iron concentrates in the cement industry. Volcanic ash mixed materials can be used as mixed materials for silicate cement or concrete.

[0032] (2) The high content of residual carbon in gasification slag is a key problem affecting its resource utilization. The present invention proposes to achieve the enrichment of residual carbon in fine particles through a simple classification process. On the one hand, it solves the problem of efficient separation of residual carbon in gasification slag, and on the other hand, the obtained carbon-rich particles can be used as a co-combustion fuel to provide hot air for the drying process of coal gasification slag.

[0033] (3) The gasified slag contains inert material Fe2O3, which affects its activity as a volcanic ash admixture. The present invention proposes to extract iron-rich materials from the gasified slag through multi-stage dry magnetic separation, and the materials can be sold as low-grade iron concentrate or cement iron corrector, generating certain economic benefits.

[0034] (4) After decarburization and iron removal, the material can be used as a volcanic ash admixture in the cement or concrete industry after multi-stage grinding. The grinding efficiency is improved by adding grinding aids and terminal classification during the multi-stage grinding process. Among them, the grinding aid is added in three stages. On the one hand, it can reduce the total amount of grinding aid used and save enterprise costs. On the other hand, the staged addition allows the finer gasified slag to continue to contact the grinding aid, preventing the gasified slag from coarsening.

[0035] (5) The process route of the present invention is clear, the equipment is simple, and the operation and maintenance costs are low. At the same time, the coarse slag and fine slag from coal gasification can be graded and utilized according to their quality, which has good economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the process flow of the classification and quality-based utilization of coal gasification slag of the present invention;

[0037] Figure 2 Thermogravimetric curve of coal gasification slag in a specific application example of the present invention;

[0038] Figure 3 This is a phase analysis diagram of coal gasification slag in a specific application example of the present invention;

[0039] Figure 4 The figure is a quality flow chart of the process for grading and quality-based utilization of coal gasification slag in a specific application example of the present invention.

[0040] In the figure: 1-first belt scale; 2-grading screen; 3-high pressure roller mill; 4-second belt scale; 5-conveyor belt; 6-drying kiln; 7-first airflow classifier; 8-first cyclone separator; 9-temporary storage bin; 10-first screw conveyor; 11-vibrating feeder; 12-permanent magnetic dry magnetic separator; 13-third belt scale; 14-grinding aid storage tank; 1401-first spray device; 1402-second spray device; 1403-third spray device; 15-first stage ball mill; 16-fourth belt scale; 17-second stage ball mill; 18-fifth belt scale; 19-third stage ball mill; 20-Roots blower; 21-second airflow classifier; 22-second cyclone separator; 23-second screw conveyor; 24-bucket elevator; 25-finished product bin. DETAILED DESCRIPTION

[0041] like Figure 1 As shown, a process for graded and quality-based utilization of coal gasification slag includes the following steps:

[0042] a. Coal gasification coarse slag screening and high pressure roller grinding;

[0043] After being weighed by the first belt scale 1, the crude slag from coal gasification is evenly fed into the grading screen 2, the mesh size of which is 4-6 mm. After being screened by the grading screen 2, the coarse particles on the screen enter the high-pressure roller mill 3 for roller crushing, and the fine particles under the screen are discharged from the discharge port at the bottom of the grading screen 2 to the conveyor belt 5. The materials after roller crushing by the high-pressure roller mill 3 also fall into the conveyor belt 5.

[0044] b. Mixing, drying and grading of materials;

[0045] After being weighed by the second belt scale 4, the coal gasification fine slag directly enters the conveyor belt 5. After being transported by the conveyor belt 5, the coal gasification fine slag enters the drying kiln 6 together with the fine particles under the screen in step a and the materials crushed by the high-pressure roller mill. Dehydration and mixing are carried out in the drying kiln 6 to obtain a dry mixed material. The hot air temperature in the drying kiln 6 is controlled at 300-400°C, and the rotation speed of the drying kiln is 4-8r / min. The drying kiln dehydrates the coal gasification coarse slag and the coal gasification fine slag and also plays a mixing role, so that the coal gasification slag is evenly mixed, so as to facilitate sorting in the air flow classifier. The mass ratio of coal gasification fine slag to coal gasification coarse slag is 1:3-1:9.

[0046] The dry mixture of gasification coarse slag and fine slag discharged from the drying kiln 6 enters the first airflow classifier 7 for sorting, and after classification, two kinds of materials, low carbon and carbon-rich, are obtained respectively. Among them, the particles of -45μm are carbon-rich materials, which enter the first cyclone separator 8 for collection through the discharge pipe at the top of the first airflow classifier 7. The carbon content of the material collected in the first cyclone separator 8 is controlled to be ≥30%, and it has a certain calorific value. It can be mixed with other fuels to generate hot air for drying the mixture of gasification coarse slag and fine slag. Particles of +45μm are low-carbon materials, and their main chemical compositions are SiO2, Al2O3 and Fe2O3, and the carbon content is controlled below 3%. The low-carbon materials enter the temporary storage bin 9 for storage, and are used as volcanic ash mixed materials after subsequent iron removal and grinding.

[0047] It should be pointed out that in the process of material classification, the yield of low-carbon and carbon-rich materials can be flexibly controlled by adjusting the speed, air volume and other process parameters of the airflow classifier.

[0048] c. Removal of iron from low carbon materials;

[0049] The low-carbon materials stored in the temporary storage bin 9 are fed into the vibrating feeder 11 through the first screw conveyor 10 at the bottom to ensure that the low-carbon materials are evenly entered into the permanent magnetic dry separator 12 for iron removal. The permanent magnetic dry separator 12 is arranged in three levels: upper, middle and lower. From top to bottom, it includes the first-level magnetic roller, the second-level magnetic roller and the third-level magnetic roller. The magnetic induction intensity of the first-level magnetic roller is 3000Gs, the magnetic induction intensity of the second-level magnetic roller is 5000Gs, and the magnetic induction intensity of the third-level magnetic roller is 8000Gs. The magnetic roller speed of the permanent magnetic dry separator 12 is controlled at 20-60r / min. After the low-carbon materials are sorted by the permanent magnetic dry separator 12, iron-removed materials and iron-rich materials are obtained. The iron-removed materials are subsequently continuously segmented and used as volcanic ash mixed materials. The iron grade of the iron-rich material is 15-45%, which can be sold as a low-grade iron concentrate or cement iron corrector.

[0050] d. Continuous segmented grinding of iron removal materials;

[0051] The material after iron removal by the permanent magnetic dry magnetic separator 12 is fed into the third belt scale 13, and then the material is transported to the first stage ball mill 15 for grinding. After the material is ground by the first stage ball mill 15, it enters the fourth belt scale 16. The material is transported from the fourth belt scale 16 to the second stage ball mill 17 for grinding. After the material is ground by the second stage ball mill 17, it enters the fifth belt scale 18. The material is transported from the fifth belt scale 18 to the third stage ball mill 19 for grinding.

[0052] There is a grinding aid storage tank 14 and a matching spraying device at the belt scale, and the spraying device is connected to the grinding aid storage tank 14 through a pipeline. The spraying device is arranged above the belt scale. Specifically, a first spraying device 1401 is arranged above the third belt scale 13, and the grinding aid added by the first spraying device 1401 is 0.3‰ to 0.5‰ of the mass of the material entering the mill. A second spraying device 1402 is arranged above the fourth belt scale 16, and the grinding aid added by the second spraying device 1402 is 0.2‰ to 0.3‰ of the mass of the material entering the mill. A third spraying device 1403 is arranged above the fifth belt scale 18, and the grinding aid added by the third spraying device 1403 is 0.1‰ to 0.2‰ of the mass of the material entering the mill. The three-stage spraying of grinding aids forms a multi-level, multi-point, and multi-level grinding aid addition method.

[0053] The material discharged from the three-stage ball mill 19 is blown to the second air classifier 21 through the Roots blower 20. After the material is classified by the second air classifier 21, the specific surface area reaches 550m 2 / kg or more of the material is collected as the final product by the second cyclone separator 22. The material whose specific surface area does not meet the requirement is transported by pipeline to the three-stage ball mill 19 for re-grinding. The product that finally meets the specific surface area requirement falls into the finished product bin 25 through the second screw conveyor 23 and the bucket elevator 24. The final product obtained in the finished product bin is a pozzolanic mixed material, which can be used as a mixed material for silicate cement.

[0054] The present invention provides a process for the graded and quality-based utilization of coal gasification slag, which mainly includes screening and rolling of coarse slag, mixed drying of fine slag and coarse slag, decarburization and iron removal of the whole material, and multi-stage grinding process. The process of the present invention can obtain carbon-rich material, iron-rich material and material with a specific surface area of ​​≥550m 2 / kg, 28d activity index ≥75% of volcanic ash mixed material, to achieve the graded and quality-based utilization of gasification coarse slag and fine slag. The obtained carbon-rich particles can be used as a blended fuel to provide hot air for the drying process of gasification slag, and the iron-rich minerals can be sold as iron correctors or low-grade iron concentrates in the cement industry. Volcanic ash mixed materials can be used as mixed materials for silicate cement or concrete.

[0055] The present invention will be further described below in conjunction with specific application examples.

[0056] 1. Physical and chemical properties of coal gasification slag;

[0057] The main components of coal gasification slag are shown in Table 1.

[0058] Table 1

[0059]

[0060] The carbon content of +45μm and -45μm particles of the coal gasification coarse slag and coal gasification fine slag after preliminary crushing is shown in Table 2.

[0061] Table 2

[0062]

[0063] Thermogravimetric analysis of coal gasification slag Figure 3 Phase analysis of coal gasification slag Figure 4 .

[0064] 2. Utilization of coal gasification slag by grade and quality;

[0065] (1) Screening and high-pressure roller grinding of coal gasification coarse slag;

[0066] The moisture content of the coarse coal gasification slag is 12.56%, and it is fed to the grading screen 2 by the first belt scale 1 at a feed rate of 15 t / h. The mesh of the grading screen is 4 mm, and the mass of the material with a particle size less than 4 mm is 12.60 t / h, and the moisture content is 14.45%, which falls to the conveyor belt 5 below. The mass of the material on the screen is 2.40 t / h, and the moisture content is 2.64%, which falls to the conveyor belt 5 after being rolled by the high-pressure roller mill 3. The moisture content of the fine coal gasification slag is 21.34%, and it is fed to the conveyor belt 5 by the second belt scale 4 at a feed rate of 5 t / h.

[0067] (2) Mixing, drying and classification of fine and coarse slag from coal gasification;

[0068] The moisture content of the mixture of coarse slag and fine slag is 14.75%, and it enters the drying kiln 6 through the conveyor belt 5. In the drying kiln 6, the inlet air temperature is 400°C and the material temperature is maintained at 150°C. After drying in the drying kiln 6, the mass of the dried material is 17.05t / h and the moisture content is 2.60%. The gasified slag enters the subsequent first airflow classifier 7. The -45μm carbon-rich material in the first airflow classifier 7 enters the cyclone separator 8 through the airflow. The mass of the carbon-rich material is 5.82t / h and the moisture content is 2.78%. The mass of the low-carbon material of +45μm is 11.68t / h and the moisture content is 2.51%, and it falls into the temporary storage bin 9.

[0069] (3) Iron removal of low-carbon materials;

[0070] The low carbon material is evenly distributed to the permanent magnetic dry separator 12 through the first screw conveyor 10 and the vibrating feeder 11. After the three-stage magnetic separation, the iron-rich material is collected from the iron-rich material outlet. The quality of the iron-rich material is 1.05t / h, the moisture content is 1.69%, and the total iron grade is 35.73%.

[0071] (4) Continuous segmented grinding of iron removal materials;

[0072] The material after iron removal enters the ball mill for grinding at a feed rate of 10.63t / h, and the grinding aids are added before each stage of grinding in a multi-level, multi-point and multi-level manner. The material first reaches the third belt scale 13. Here, the first spray device 1401 sprays 0.3‰ of the material mass with grinding aids. The material then enters a first-stage ball mill 15 for grinding. The fourth belt scale 16 sprays 0.2‰ of the material mass with grinding aids, and the fifth belt scale 18 sprays 0.1‰ of the material mass with grinding aids. After three stages of grinding, the material enters the second air classifier 21 through the Roots blower 20. After classification by the second air classifier 21, the specific surface area reaches 550m 2 / kg or more of the material is collected as the final product by the second cyclone separator 22. The material whose specific surface area does not meet the requirements is conveyed to the three-stage ball mill 19 for re-grinding. The final product falls into the final finished product bin 25 through the second screw conveyor 23 and the bucket elevator 24.

[0073] Finally, after grading and quality-differentiated utilization of 15 tons of crude coal gasification slag and 5 tons of fine coal gasification slag, 5.82 tons of carbon-rich material, 1.05 tons of iron-rich material and 10.42 tons of volcanic ash mixed material were obtained, with moisture contents of 2.78%, 1.69% and 0.60% respectively.

Claims

1. A process for utilizing coal gasification slag by classification and quality, characterized in that The following steps are involved: a. Coal gasification coarse slag screening and high pressure roller grinding; After being weighed by the first belt scale, the crude slag from coal gasification is evenly fed into the grading screen. After being screened by the grading screen, the coarse particles on the screen enter the high-pressure roller mill for roller crushing, and the fine particles under the screen are discharged from the discharge port at the bottom of the grading screen to the conveyor belt; the materials after roller crushing by the high-pressure roller mill also fall into the conveyor belt; b. Mixing, drying and grading of materials; After being weighed by the second belt scale, the coal gasification fine slag directly enters the conveyor belt, and is transported by the conveyor belt. The coal gasification fine slag, the fine particles under the screen in step a, and the materials crushed by the high-pressure roller mill enter the drying kiln together, and are dehydrated and mixed in the drying kiln to obtain a dry mixed material; The dried mixed material enters the first airflow classifier for sorting, and obtains low-carbon and carbon-rich materials respectively; the carbon-rich material enters the first cyclone separator through the discharge pipe at the top of the first airflow classifier for collection; the low-carbon material enters the temporary storage bin for storage; c. Removal of iron from low carbon materials; The low-carbon materials stored in the temporary storage bin are fed into the vibrating feeder through the first screw conveyor at the bottom to ensure that the low-carbon materials are evenly fed into the permanent magnetic dry separator for iron removal. After the low-carbon materials are separated by the permanent magnetic dry separator, iron-removed materials and iron-rich materials are obtained. d. Continuous segmented grinding of iron removal materials; The iron-removed materials are fed into the ball mill for grinding, and the discharged ground materials are blown to the second air classifier through the Roots blower. After the ground materials are classified by the second air classifier, the materials with specific surface area reaching the set value are collected by the second cyclone separator as the final product; the materials with specific surface area not reaching the set value are returned to the ball mill for further grinding; The materials collected by the second cyclone separator are transported to the finished product warehouse through the second screw conveyor and bucket elevator; In step b: the particle size of the carbon-rich material is less than 45 μm, the carbon content of the carbon-rich material is controlled to be more than 30%, and the carbon-rich material is mixed with other fuels to generate hot air for drying the mixed material; The particle size of low-carbon materials is greater than 45 μm, and their main chemical composition is SiO2, Al2O3 and Fe2O3, and the carbon content is controlled below 3%; During the mixed material sorting process, by adjusting the process parameters of the first airflow classifier, including the rotation speed and air volume, the yield of low-carbon and carbon-rich materials can be regulated; In step c: the obtained iron-rich material has an iron grade of 15-45%, and can be sold as low-grade iron concentrate or cement iron corrector; In step d: the setting value is 550m 2 / kg, the materials whose specific surface area does not reach the set value are returned to the three-stage ball mill for further grinding; the final product obtained in the finished product warehouse is a volcanic ash mixture, which can be used as a mixing material for silicate cement or concrete.

2. The process for utilizing coal gasification slag by classification and quality according to claim 1, characterized in that: In step a: the mesh size of the grading sieve is 4 to 6 mm.

3. The process for utilizing coal gasification slag by classification and quality according to claim 1, characterized in that: In step b: the hot air temperature in the drying kiln is controlled at 300-400° C. and the rotation speed of the drying kiln is 4-8 r / min.

4. The process for utilizing coal gasification slag by classification and quality according to claim 1, characterized in that: The mass ratio of coal gasification fine slag to coal gasification coarse slag is controlled to be 1:3 to 1:

9.

5. The process for utilizing coal gasification slag by classification and quality according to claim 1, characterized in that: In step c: the permanent magnetic dry separator is arranged in three levels: upper, middle and lower, and includes, from top to bottom, a first-level magnetic roller, a second-level magnetic roller and a third-level magnetic roller, the magnetic induction intensity of the first-level magnetic roller is 3000Gs, the magnetic induction intensity of the second-level magnetic roller is 5000Gs, and the magnetic induction intensity of the third-level magnetic roller is 8000Gs; the roller speed of the permanent magnetic dry separator is controlled at 20-60r / min.

6. The process for utilizing coal gasification slag by classification and quality according to claim 1, characterized in that: In step d: the ball mill includes a first-stage ball mill, a second-stage ball mill and a third-stage ball mill; the de-ironing material is first fed into the third belt scale, and then the de-ironing material is transported to the first-stage ball mill for grinding; the de-ironing material is ground in the first-stage ball mill and then enters the fourth belt scale, and then the de-ironing material is transported by the fourth belt scale to the second-stage ball mill for grinding; the de-ironing material is ground in the second-stage ball mill and then enters the fifth belt scale, and then the de-ironing material is transported by the fifth belt scale to the third-stage ball mill for grinding.

7. The process for utilizing coal gasification slag by classification and quality according to claim 6, characterized in that: A first spray device is arranged above the third belt scale, a second spray device is arranged above the fourth belt scale, and a third spray device is arranged above the fifth belt scale. The first spray device, the second spray device and the third spray device are all connected to the grinding aid storage tank through a pipeline; Among them, the grinding aid added by the first spray device is 0.3‰~0.5‰ of the mass of the material entering the first stage ball mill; the grinding aid added by the second spray device is 0.2‰~0.3‰ of the mass of the material entering the second stage ball mill; the grinding aid added by the third spray device is 0.1‰~0.2‰ of the mass of the material entering the third stage ball mill.

Images