Comprehensive utilization process for superfine pulverization and zero waste discharge of coal gasification slag

Abstract

The invention discloses a comprehensive utilization process for superfine pulverization and zero waste discharge of coal gasification slag, and belongs to the field of solid waste recycling. The process comprises the following steps: treating coal gasification slag with different particle fractions; carrying out spiral chute-shaking table separation on carbon-rich components and carrying out gradient utilization on heat energy; and preparing ceramic and ceramsite or different types of building mortar. According to the process disclosed by the invention, the coal gasification slag is converted into high-purity silicon-aluminum-based powder with the SiO2 / Al2O3 molar ratio of 1.0-2.5 through superfine pulverization. The recycling rate of the whole process is larger than or equal to 97%, and zero waste discharge is achieved.

Description

Technical Field

[0001] This invention pertains to the high-value utilization technology of coal-based solid waste, specifically involving a comprehensive utilization process for ultrafine pulverization of coal gasification slag with zero waste discharge. The process of this invention can produce high-performance foam ceramics and lightweight ceramsite or different types of building mortar. Background Technology

[0002] Coal gasification technology, as one of the core approaches to clean coal utilization, occupies an important position in my country's energy system. However, the large-scale stockpiling of coal gasification slag has become one of the key challenges restricting the sustainable development of the industry. According to statistics, my country's coal gasification slag emissions exceeded 65 million tons in 2023, of which fine slag with a particle size of less than 100 μm accounted for more than 40%. This type of fine slag has a large specific surface area and complex composition (SiO2 content 35%-55%, Al2O3 content 15%-25%, residual carbon 10%-30%), and traditional processes are difficult to achieve efficient sorting. Direct landfilling can easily cause leachate and dust pollution, posing significant environmental risks.

[0003] In recent years, while research on the resource utilization of coal gasification slag has made some progress, existing technologies still have significant limitations. Patent CN117800753A proposes a method for preparing composite ceramsite from coal gasification slag using airflow milling technology combined with laterite and oily sludge. However, the resulting ceramsite product has high crystallinity of silicon-aluminum components and low activity (specific surface area <400 m² / kg), with a cylinder compressive strength ≤2.1 MPa, making it difficult to meet the raw material requirements for high-performance ceramics. Patent CN118893074A achieves graded and differentiated utilization of coal gasification slag through high-pressure roller milling and multi-stage magnetic separation, but this method has high energy consumption.

[0004] Furthermore, existing technologies largely focus on utilizing coal gasification slag as an additive component. For example, patent CN102372496A discloses a method for preparing ceramsite by mixing gasification slag with clay, flux, and water in a certain proportion, granulating, and then calcining; however, the product performance still needs improvement. Patent CN105130487A discloses a method for preparing filter ceramics by mixing gasification slag with fly ash, binder, flux, and water in a certain proportion and then calcining; however, this method has high energy consumption. Patent CN104774023A discloses a method for preparing lightweight ceramsite by mixing gasification slag with fly ash, potassium feldspar, sodium feldspar, and additives; however, this method has low utilization of coal gasification slag. These patented methods all suffer from low utilization of coal gasification slag, high energy consumption, and poor product performance to varying degrees. Additionally, the resource utilization rate of these processes is ≤85%, and 10%~15% of inert tailings are generated that need to be landfilled. Summary of the Invention

[0005] Based on the above-mentioned technical problems, this invention proposes a comprehensive utilization process for coal gasification slag with ultrafine pulverization and zero waste emission, which solves the bottlenecks of insufficient ultrafine pulverization activity, low product added value and serious secondary pollution in the existing process, and realizes the full-scale high-value utilization of coal gasification slag.

[0006] The technical solution of the present invention to achieve the above objectives is as follows.

[0007] A comprehensive utilization process for coal gasification slag through ultrafine pulverization with zero waste emission includes the following steps: S1. Classification and treatment of coal gasification slag Depending on the source and particle size, coal gasification slag may be crushed or not, to convert it into ultrafine coal gasification slag powder with a particle size of <1 mm. S2, Carbon-rich component sorting and thermal energy cascade utilization The ultrafine powder of coal gasification slag obtained from S1 is formulated into a slurry with a mass concentration of 15%~25%. After coarse separation by spiral chute, decarbonized material A and carbon-rich slurry with a carbon content ≥35% are separated. The carbon-rich slurry is further refined by shaking table to obtain decarbonized material B and rich coal fuel with a calorific value ≥1500 kcal / kg. The rich coal fuel is used for coal-fired power generation. S3. Application of Kaolinite Phase Detection and Classification The decarburized material A and decarburized material B obtained in S2 are mixed to obtain a decarburized material mixture. Then, the decarburized material mixture is subjected to kaolinite phase detection and analysis. If the kaolinite phase content of the decarburized material is >10%, then further processing in S31 and S32 is selected. S31. Take 100 parts of the decarburized material mixture according to the mass ratio, add 3-5 parts of binder and an appropriate amount of co-solvent, and then ball mill the resulting mixture; then spread the mixture in a mold and heat it to 600 ℃ at a rate of 5 ℃ / min and hold it for 30 min, then heat it to 1250~1350 ℃ at a rate of 3 ℃ / min and hold it for 10~60 min to sinter, and obtain foam ceramic with compressive strength ≥4.0 MPa and water absorption ≤0.5%; S32. Using the waste generated during the preparation of foam ceramics in S31 as raw material, a certain amount of foaming agent, co-solvent and binder are added. After being mixed evenly by mechanical ball milling, the mixture is first pre-fired at a certain temperature, and then sintered at 1100~1200℃ for 60 min to obtain lightweight ceramsite with a compressive strength ≥3.0 MPa and a bulk density ≤600 kg / m³. Kaolinite (mainly composed of kaolinite, Al2O3·2SiO2·2H2O) undergoes a phase transformation during high-temperature sintering (1250–1350 ℃): dehydroxylation (400–600 ℃) produces metakaolinite, and mullite crystallization (>1000 ℃) produces acicular mullite (3Al2O3·2SiO2). Mullite is the core phase for high strength in ceramics, imparting compressive strength (≥4.0 MPa) and low water absorption (≤0.5%). If the kaolinite content is <10%, insufficient mullite formation leads to loose and cracked ceramics.

[0008] The decarburized material A and decarburized material B obtained from S2 are mixed to obtain a decarburized material mixture. Then, the decarburized material mixture is subjected to kaolinite phase detection and analysis. If the kaolinite phase content of the decarburized material is ≤10%, then S31(a) or S31(a) and S32(a) are selected for further processing. S31(a) Detect the iron content in the decarbonized material mixture. If the Fe content in the decarbonized material mixture is ≤1%, take 100 parts of the gasification slag and add 30%~50% cement, 5%~10% gypsum and 0.1%~5% additives according to mass fraction. The additives are one of high-adhesion tile adhesive, quicklime, waterproofing agent or clay. After uniform gradation mixing, a building mortar is prepared. If the Fe content in the decarbonized material mixture is >1%, then select S32(a) for further processing. S32(a) The decarbonized material mixture is separated by a magnetic separator to obtain iron-rich concentrate with an Fe content ≥30% and non-magnetic tailings; using the non-magnetic tailings as raw material, 30%~50% cement, 5%~10% gypsum and 0.1%~5% additives are added by mass ratio, wherein the additives are one of high-adhesion tile adhesive, quicklime, waterproofing agent or clay, and the mixture is uniformly mixed by gradation to obtain building mortar; the iron-rich concentrate is used as an auxiliary material for iron and steel smelting.

[0009] Kaolinite contains reactive SiO2. If the content is too high, it may react in the alkaline environment of cement (pH>12): SiO2 + 2NaOH → Na2SiO3 + H2O. The resulting sodium silicate gel absorbs water and expands, leading to mortar cracking (expansion rate can reach 0.1–0.6%). Controlling the kaolinite content to ≤10% and low iron content (Fe≤1%) can prevent the cracking problem in the prepared building mortar.

[0010] Preferably, in S2, the lateral tilt angle of the spiral chute is set to 5.5°~6.5°; the lateral slope of the shaking table is set to 1.5°~2.5°, the stroke is 8~25 mm, and the stroke rate is 180~320 times / min.

[0011] Preferably, step S2 further includes a step of recovering and utilizing the heat from the power generation and pyrolysis flue gas after SCR denitrification to NOx≤50 mg / m³.

[0012] Preferably, in the process of preparing foam ceramics in S31, the temperature of the ceramic sintering holding stage is 1250 ℃~1350 ℃, and the holding time is 10 min~60 min.

[0013] Preferably, in S31 or 32, the binder is at least one of bentonite, clay, and borax.

[0014] Preferably, the foaming agent in S32 is a calcium carbonate and sodium silicate composite with a mass ratio of 2:1. More preferably, the calcium carbonate particle size in the foaming agent is ≤10 μm, and the sodium silicate modulus is 2.4~2.6.

[0015] Preferably, the SiO2 / Al2O3 molar ratio in the raw materials for preparing building mortar described in S31(a) and 32(a) is 2.0~2.5; and the 28-day compressive strength of the building mortar is ≥20 MPa.

[0016] Preferably, the SiO2 / Al2O3 molar ratio in the non-magnetic tailings obtained after magnetic separation in S32(a) is 2.0~2.5.

[0017] Preferably, the iron-rich concentrate described in S32(a) is used as an auxiliary material in iron and steel smelting.

[0018] The comprehensive utilization process of ultrafine pulverization of coal gasification slag with zero waste emission of this invention solves three major industry problems in the utilization of coal gasification fine slag: easy agglomeration, low activity of silicon and aluminum, and low added value of products. Compared with the prior art, it has the following advantages:

[0019] (1) Full-process resource utilization and zero waste discharge: The coal gasification slag from different regions and sources is sorted and crushed. Combined with the synergistic optimization of the spiral chute-shaking table inclination / slope parameters (carbon recovery rate increased by 30%), the "full conversion and zero waste discharge" is achieved, and the problem of coal gasification tailings storage is completely eliminated.

[0020] (2) Multi-element co-production of high-value silicon-based materials: Based on the source and properties of coal gasification slag, this invention first sorts the carbon-rich components and utilizes the thermal energy in a cascade manner. Then, it performs kaolinite phase detection and analysis on the decarbonized material and, if necessary, Fe content analysis. Based on the properties of the raw materials, it selects the appropriate comprehensive utilization process route to prepare high-performance foam ceramic products (compressive strength ≥ 4.0 MPa, water absorption ≤ 0.5%) and lightweight ceramsite products (cylindrical compressive strength ≥ 3.0 MPa, bulk density ≤ 600 kg / m³). 3The company has developed a comprehensive utilization system for high-value coal gasification residues, including building mortar products (28-day compressive strength ≥20 MPa), which significantly enhances the added value of resources.

[0021] (3) Process integration innovation and performance breakthrough: The ultrafine powdering synergistic carbon-rich component sorting and thermal energy cascade utilization technology, as well as the kaolinite phase detection and classification application processing method adopted for the first time in this invention, improve the reactivity of silicon and aluminum components in high-performance foam ceramics and lightweight ceramsite by 30%. The introduction of cascade heating sintering process and composite foaming process further improves the density of the prepared foam ceramic products and the strength of lightweight ceramsite by 25% and 40%, respectively. Attached Figure Description

[0022] Figure 1 The XRD phase spectra of the mixed decarbonized materials obtained from samples 2 and 4 are shown.

[0023] Figure 2 The image shows the XRD phase spectrum of the foam ceramic sample in Example 1.

[0024] Figure 3 The diagram shows the 28-day compressive strength of the cement mortar prepared in Examples 2, 4 to 7. Detailed Implementation

[0025] In the embodiments of the present invention, the methods for measuring or characterizing the relevant parameters of raw materials and products are described as follows: The average particle size of the coal gasification slag was tested according to the national standard GB / T 19077.1-2008 Particle Size Analysis by Laser Diffraction; the carbon content was determined according to GB / T 35964-2018 Determination of Residual Carbon Content in Coal Gasification Slag (High Temperature Loss on Ignition Method); the SiO2 content, Al2O3 content, and Fe2O3 content were determined according to GB / T 176-2017 Cement Chemical Analysis Methods by X-ray Fluorescence Spectrometry (XRF); the moisture content was determined according to GB / T 211-2017 Determination of Total Moisture in Coal by Constant Weight Method at 105℃; and the calorific value was determined according to GB / T 213-2008 Determination of Calorific Value of Coal.

[0026] The bulk density, 1-hour water absorption rate and cylinder compressive strength of coal gasification slag ceramics and ceramsite are tested according to the national standard GB / T 17431-2010 800 grade artificial lightweight aggregate standard.

[0027] The test method for the 28-day compressive strength of building mortar is based on the industry standard "JGJ / T 70-2009 Standard for Test Methods of Basic Performance of Building Mortar". All other parameters are characterized using conventional testing methods in this field. Unless otherwise specified, all contents mentioned are mass percentages.

[0028] In the following embodiments prepared according to the present invention, the coal gasification slag used comes from Lurgi pressurized coal gasifier, high-temperature molten slag gasification slag, UGI gasification slag, Texaco coal-water slurry gasifier, Shell coal gasifier, and aerospace furnace gasification slag. For the preparation of ceramics and ceramsite, the kaolinite phase content of the coal gasification slag is required to be ≥10%; for the preparation of building mortar, the kaolinite phase content of the coal gasification slag is required to be <10%, and the Fe content is required to be <1%. The composition of coal gasification slag from different sources (including kaolinite phase content and Fe content) is shown in Table 1.

[0029] Table 1. Composition and Properties of Raw Materials

[0030] sample Carbon content / % <![CDATA[SiO2 content / %]]> <![CDATA[Al2O3 content / %]]> Fe content / % Kaolinite phase content / % Calorific value (kcal / kg) 1 18 48 22 0.7 11 1600 2 32 42 18 5 6 1500 3 25 50 24 3 12 1700 4 28 45 25 0.4 7 1400 5 22 47 20 6 8 1550 6 15 52 25 9 5 1450 7 10 38 18 1 9 1200 8 8 60 28 4 14 1100 9 28 40 15 0.3 12 1600

[0031] Typical XRD phase spectra of the mixed decarburized material obtained by using samples 2 and 4 as raw materials in this invention are shown in the figure below. Figure 1 As shown. By Figure 1 It is evident that the mixed decarburized materials obtained in Examples 2 and 4 contain very little kaolinite phase, making them suitable for mortar preparation. In the other examples where the comprehensive utilization product is cement mortar, the XRD phase spectrum of the mixed decarburized materials is similar to... Figure 1 Similar to these, they will not be listed separately.

[0032] The process steps of this invention include: Step 1: Classification and treatment of coal gasification slag Depending on the source and particle size, coal gasification slag may be crushed or not, to convert it into ultrafine coal gasification slag powder with a particle size of <1 mm. Step 2: Sorting of carbon-rich components and cascade utilization of thermal energy The ultrafine coal gasification slag powder obtained in step 1 is formulated into a slurry with a mass concentration of 15%~25%. After coarse separation by a spiral chute, decarbonized material A and carbon-rich slurry with a carbon content ≥35% are separated. The carbon-rich slurry is further refined by a shaking table to obtain decarbonized material B and rich coal fuel with a calorific value ≥1500 kcal / kg. The rich coal fuel is used for coal-fired power generation. Step 3: Application of Kaolinite Phase Detection and Classification The decarburized material A and decarburized material B obtained in step 2 are mixed to obtain a decarburized material mixture. Then, the decarburized material mixture is subjected to kaolinite phase detection and analysis. If the kaolinite phase content of the decarburized material is >10%, then steps 31 and 32 are selected for further processing. Step 31: Take 100 parts of the decarburized material mixture according to the mass ratio, add 3-5 parts of binder and an appropriate amount of co-solvent, and then ball mill the resulting mixture; then spread the mixture in a mold and heat it to 600 ℃ at a rate of 5 ℃ / min and hold it for 30 min, then heat it to 1250~1350 ℃ at a rate of 3 ℃ / min and hold it for 10~60 min to sinter, and obtain foam ceramic with compressive strength ≥4.0 MPa and water absorption ≤0.5%; Step 32: Using the waste generated in the foam ceramic preparation process in Step 31 as raw material, a certain amount of foaming agent, co-solvent and binder are added. After being mixed evenly by mechanical ball milling, the mixture is first pre-fired at a certain temperature, and then sintered at 1100~1200 ℃ for 60 min to obtain lightweight ceramsite with a compressive strength ≥3.0 MPa and a bulk density ≤600 kg / m³. The decarburized material A and decarburized material B obtained in step 2 are mixed to obtain a decarburized material mixture. Then, the decarburized material mixture is subjected to kaolinite phase detection and analysis. If the kaolinite phase content of the decarburized material is ≤10%, then step 31(a) or steps 31(a) and 32(a) are selected for further processing. Step 31(a): Detect the iron content in the decarbonized material mixture. If the Fe content in the decarbonized material mixture is ≤1%, take 100 parts of the gasification slag and add 30%~50% cement, 5%~10% gypsum, and 0.1%~5% additives according to mass fraction. The additives are one of high-adhesion tile adhesive, quicklime, waterproofing agent, or clay. After uniform mixing through gradation, a building mortar is prepared. If the Fe content in the decarbonized material mixture is >1%, proceed to step 32(a) for further processing. Step 32(a): The decarbonized material mixture is separated by a magnetic separator to obtain iron-rich concentrate with an Fe content ≥30% and non-magnetic tailings; using the non-magnetic tailings as raw material, 30%~50% cement, 5%~10% gypsum and 0.1%~5% additives are added by mass ratio, wherein the additives are one of high-adhesion tile adhesive, quicklime, waterproofing agent or clay, and the mixture is uniformly mixed by gradation to obtain building mortar; the iron-rich concentrate is used as an auxiliary material for iron and steel smelting.

[0033] In a preferred embodiment, in step 2, the lateral tilt angle of the spiral chute is set to 5.5°~6.5°; the lateral slope of the shaking table is set to 1.5°~2.5°, the stroke is 8~25 mm, and the stroke rate is 180~320 times / min.

[0034] In a preferred embodiment, step 2 further includes a step of recovering and utilizing the heat from the power generation and pyrolysis flue gas after SCR denitrification to NOx≤50 mg / m³.

[0035] In a preferred embodiment, during the preparation of foam ceramics in step 31, the temperature of the ceramic sintering holding stage is 1250 ℃~1350 ℃, and the holding time is 10 min~60 min.

[0036] In a preferred embodiment, in step 31 or 32, the binder is at least one of bentonite, clay, and borax.

[0037] In a preferred embodiment, the foaming agent in step 32 is a calcium carbonate and sodium silicate composite with a mass ratio of 2:1. More preferably, the calcium carbonate particle size in the foaming agent is ≤10 μm, and the sodium silicate modulus is 2.4~2.6.

[0038] In a preferred embodiment, the SiO2 / Al2O3 molar ratio in the raw materials for preparing building mortar in steps 31(a) and 32(a) is 2.0~2.5; and the 28-day compressive strength of the building mortar is ≥20 MPa.

[0039] In a preferred embodiment, the SiO2 / Al2O3 molar ratio in the non-magnetic tailings obtained after magnetic separation in step 32(a) is 2.0~2.5.

[0040] To more clearly describe the technical solution and advantages of the present invention, the technical content of the present invention will be further described in detail below with reference to specific embodiments.

[0041] Example 1

[0042] Using the coal gasification slag produced by the Texaco gasifier as raw material (i.e., sample 1), the specific implementation steps are as follows:

[0043] (1) The coal gasification slag is prepared into a slurry with a mass concentration of 20% (the average particle size of the coal gasification slag is 50 μm, and no crushing is required). The slurry is coarsely separated by a spiral chute (6° transverse inclination angle) to separate decarbonized material A and carbon-rich slurry (carbon content 36%). The carbon-rich slurry is then finely separated by a shaking table (15 mm stroke, 250 strokes / min, 2° transverse slope) to obtain decarbonized material B and rich coal fuel (calorific value 2000 kcal / kg). The rich coal fuel is used for coal-fired power generation.

[0044] (2) Combine decarburized material A and decarburized material B, mix them evenly to obtain mixed decarburized material, and then test the kaolinite phase content. The results show that the kaolinite phase content is 11%, so it can be used as a raw material for preparing ceramics and ceramsite.

[0045] (3) Take 100 kg of mixed decarburized material, then mix it with 30 kg of diatomaceous earth and 14 kg of talc, spread it in a mold and sinter it in stages (heat it to 600 ℃ at a heating rate of 5 ℃ / min, then heat it to 1280 ℃ at a heating rate of 3 ℃ / min and hold it for 50 min) to obtain ceramic products (compressive strength 4.5 MPa, water absorption 0.3%). Add 6% foaming agent (CaCO3:Na2SiO3=2:1) ​​to the ceramic waste generated in the ceramic preparation process, and sinter it in a rotary kiln at a temperature of 1150 ℃ to obtain lightweight ceramsite (cylindrical compressive strength 3.5 MPa, bulk density 580 kg / m³).

[0046] Figure 2 The image shows the XRD pattern of the foam ceramic sample from Example 1. Figure 2 It can be seen that the main phases of the foam ceramic sample are cordierite and quartz. The cordierite phase has the characteristics of low dielectric constant and high mechanical strength, which makes the sample have the characteristics of low thermal conductivity and high compressive strength.

[0047] Example 2

[0048] Using coal gasification slag produced by pressurized gasification of pulverized coal in a Lurgi furnace as raw material (i.e., sample 2), the implementation steps are as follows:

[0049] (1) The coal gasification slag is crushed from 5 mm to less than 1 mm by a jaw crusher and a ball mill to obtain fine coal gasification slag powder (<1 mm).

[0050] (2) The obtained coal gasification slag fine powder is prepared into a slurry with a mass concentration of 18%. The slurry is coarsely separated by a spiral chute (lateral inclination angle of 7°) to separate decarbonized material A and carbon-rich slurry (carbon content of 38%). The carbon-rich slurry is then finely separated by a shaking table (stroke of 20 mm, stroke of 280 times / min, lateral slope of 3°) to obtain decarbonized material B and rich coal fuel (calorific value of 1500 kcal / kg). The rich coal fuel is used for coal blending and power generation.

[0051] (3) Combine decarbonized material A and decarbonized material B, mix them evenly to obtain mixed decarbonized material, and then test the kaolinite phase content. The results show that the kaolinite phase content is 6%.

[0052] (4) Further Fe content analysis was performed on the mixed decarbonized material. The Fe content test result was 5%, so further magnetic separation was required to remove iron.

[0053] (5) The mixed decarbonized material is separated by three-stage magnetic separation (3000 Gs, 6000 Gs, 10000 Gs) to obtain iron-rich concentrate (Fe content 30%) and non-magnetic tailings (Fe content 0.6%, SiO2 content 51%, Al2O3 content 26%).

[0054] (6) Take 100 kg of non-magnetic tailings (Fe content 0.6%, SiO2 content 51%, Al2O3 content 26%) as the main raw material, add 40% cement (compliant with GB 175-2007 general silicate cement standard), 8% gypsum (dihydrate gypsum, purity ≥90%), and 0.8% tile adhesive by mass ratio, mix evenly to obtain building tile adhesive mortar. After standard curing for 28 days, according to the industry standard "JGJ / T 70-2009", the compressive strength after 28 days reaches 22.0 MPa (meeting the requirement of ≥20 MPa).

[0055] Example 3

[0056] Using the gasification slag produced by the Shell coal gasifier as raw material (i.e., sample 3), the implementation steps are as follows:

[0057] (1) The coal gasification slag is made into a slurry with a mass concentration of 22% (the average particle size of the gasification slag is 45 μm < 1 mm, so there is no need to crush it). Then, the decarbonized material A and the carbon-rich slurry (containing 40% carbon) are separated by a spiral chute (with a transverse inclination angle of 5°). The carbon-rich slurry is then finely selected by a shaking table with a stroke of 10 mm, 300 strokes / min, and a transverse slope of 1.5° to obtain decarbonized material B and rich coal fuel (calorific value of 1700 kcal / kg). The rich coal fuel is used for coal blending and power generation.

[0058] (2) Combine decarburized material A and decarburized material B, mix them evenly to obtain mixed decarburized material, and then test the kaolinite phase content. The results show that the kaolinite phase content is 12%, so it can be used as a raw material for preparing ceramics and ceramsite.

[0059] (3) Take 100 kg of mixed decarburized material, then mix it with 12 kg of kaolin and 4 kg of bentonite, spread it in a mold and sinter it in stages (heat it to 600 ℃ at a heating rate of 5 ℃ / min, then heat it to 1320 ℃ at a heating rate of 3 ℃ / min and hold it for 40 min) to obtain ceramic products (compressive strength 4.8 MPa, water absorption 0.3%). Add 5% foaming agent (CaCO3:Na2SiO3=2:1) ​​to the ceramic waste generated in the ceramic preparation process, and sinter it in a rotary kiln at a temperature of 1150 ℃ to obtain lightweight ceramsite (bulk density 520 kg / m³, cylinder compressive strength 3.8 MPa).

[0060] Example 4

[0061] Using coal gasification slag produced by the aerospace furnace as raw material (i.e., sample 4), the implementation steps are as follows:

[0062] (1) The coal gasification slag is made into a slurry with a mass concentration of 25% (the average particle size of the gasification slag is 40 μm < 1 mm, so there is no need to crush it). The slurry is coarsely separated by a spiral chute (transverse inclination angle of 8°) to separate decarbonized material A and carbon-rich slurry (carbon content of 33%). The carbon-rich slurry is then finely separated by a shaking table (stroke of 25 mm, stroke of 180 times / min, transverse slope of 0.5°) to obtain decarbonized material B and rich coal fuel (calorific value of 1400 kcal / kg). The rich coal fuel is used for coal blending power generation.

[0063] (2) Decarbonized material A and decarbonized material B were combined and mixed evenly to obtain mixed decarbonized material. Then, the kaolinite phase content was detected. The results showed that the kaolinite phase content was 7%.

[0064] (3) Further Fe content analysis was performed on the mixed decarburized material. The iron content test result was 0.4%, so it was directly used as the raw material for the prepared mortar.

[0065] (4) Take 100 kg of mixed decarbonized material as the main raw material, add 45% cement (compliant with GB 175-2007), 8% gypsum (dihydrate gypsum, purity ≥90%), and 5% waterproofing agent by mass ratio, and mix evenly to obtain waterproof mortar for building. After standard curing for 28 days, according to the test of "JGJ / T 70-2009", the compressive strength after 28 days reaches 21.0 MPa (meeting the requirement of ≥20 MPa).

[0066] Example 5

[0067] Using coal gasification slag produced by a dry-process Lurgi furnace as raw material (i.e., sample 5), the implementation steps are as follows:

[0068] (1) The coal gasification slag is crushed from 3 mm to less than 1 mm by a jaw crusher and a ball mill to obtain fine coal gasification slag powder.

[0069] (2) The fine powder of coal gasification slag is prepared into a slurry with a mass concentration of 18%. This slurry is then coarsely separated using a spiral chute (7.5° transverse inclination) to separate decarbonized material A and carbon-rich slurry (37% carbon content). The carbon-rich slurry is then finely separated using a shaking table (22 mm stroke, 260 strokes / min, 3.5° transverse slope) to obtain decarbonized material B and rich coal fuel (calorific value 1550 kcal / kg). The rich coal fuel is used for coal-fired power generation.

[0070] (3) Combine decarbonized material A and decarbonized material B, mix them evenly to obtain mixed decarbonized material, and then test the kaolinite phase content. The results show that the kaolinite phase content is 8%.

[0071] (4) Further Fe content analysis was performed on the mixed decarbonized material. The Fe content was 6%, so further magnetic separation was required to remove iron.

[0072] (5) The mixed decarbonized material is separated by a permanent magnet roller separator (3000 / 6000 / 10000 Gs three-stage gradient) to obtain iron-rich concentrate (Fe content 32%) and non-magnetic tailings (Fe content 0.7%, SiO2 content 50.2%, Al2O3 content 21.3%, SiO2 / Al2O3 molar ratio = 2.36).

[0073] (6) Take 100 kg of non-magnetic tailings, add 42% cement, 7% gypsum, and 4% quicklime by mass ratio, and mix to prepare lime mortar for construction. The compressive strength reaches 22.5 MPa (>20 MPa) after 28 days.

[0074] Example 6

[0075] Using coal gasification slag produced by the aerospace furnace gasifier as raw material (i.e., sample 6), the implementation steps are as follows:

[0076] (1) Fine coal gasification slag powder was prepared into a slurry with a mass concentration of 16% (the average particle size of the gasification slag was 120 μm, and no crushing was required). The decarbonized material A and the carbon-rich slurry (carbon content 39%) were obtained by coarse selection in a spiral chute (inclination angle 5.2°). The rich coal fuel (calorific value 1450 kcal / kg) was obtained by fine selection in a shaking table (stroke 12 mm, stroke 290 times / min, slope 1.8°). The rich coal fuel was used for coal blending power generation.

[0077] (2) Decarbonized material A and decarbonized material B were combined and mixed evenly to obtain mixed decarbonized material. Then, the kaolinite phase content was detected. The results showed that the kaolinite phase content was 5%.

[0078] (3) Further Fe content analysis was performed on the mixed decarbonized material. The Fe content test result was 9%, so further magnetic separation was required to remove iron.

[0079] (4) The mixed decarbonized material is separated by a permanent magnet roller separator (3000 / 6000 / 10000 Gs three-stage gradient) to obtain iron-rich concentrate (Fe content 31%) and non-magnetic tailings (Fe content 0.8%, SiO2 content 54.6%, Al2O3 content 26.1%, SiO2 / Al2O3 molar ratio = 2.09).

[0080] (5) Take 100 kg of non-magnetic tailings, add 38% cement, 9% gypsum and 0.2% water-reducing agent according to the mass ratio to make mortar, and the compressive strength after 28 days is 21.8 MPa (>20 MPa).

[0081] Example 7

[0082] Using coal gasification slag produced by the Texaco coal-water slurry gasifier as raw material (i.e., sample 7), the implementation steps are as follows:

[0083] (1) Fine coal gasification slag powder was prepared into a slurry with a mass concentration of 24% (average particle size of material 800 μm, no crushing required). Decarbonized material A and carbon-rich slurry (carbon content 28%) were obtained by coarse separation in a spiral chute (inclination angle 8°). Rich coal fuel (calorific value 1200 kcal / kg) was obtained by fine separation in a shaking table (stroke 18 mm, stroke 230 times / min, slope 4°). The rich coal fuel was used for coal blending power generation.

[0084] (2) Decarbonized material A and decarbonized material B were combined and mixed evenly to obtain mixed decarbonized material. Then, the kaolinite phase content was detected. The results showed that the kaolinite phase content was 9%.

[0085] (3) Further Fe content analysis was performed on the mixed decarburized material. The Fe content test result was 1%, so it can be used as a raw material for direct preparation of mortar.

[0086] (4) Take 100 kg of mixed decarbonized material, add 50% cement, 5% gypsum and 5% additives according to the mass ratio, and mix evenly. The compressive strength after 28 days is 20.3 MPa (>20 MPa).

[0087] Example 8

[0088] Using aerospace furnace gasification slag as raw material (i.e., sample 8), the implementation steps are as follows:

[0089] (1) Fine coal gasification slag powder was prepared into a slurry with a mass concentration of 15% (average particle size of 90 μm, no crushing required). Decarbonized material A and carbon-rich slurry (carbon content 30%) were obtained by coarse separation using a spiral chute (inclination angle 5.8°). Rich coal fuel (calorific value 1100 kcal / kg) was obtained by fine separation using a shaking table (stroke 10 mm, stroke 310 times / min, slope 1.2°). The rich coal fuel was used for coal blending power generation.

[0090] (2) Combine decarburized material A and decarburized material B, mix them evenly to obtain mixed decarburized material, and then test the kaolinite phase content. The results show that the kaolinite phase content is 14%, so it can be used as a raw material for preparing ceramics and ceramsite.

[0091] (3) Take 100 kg of mixed decarbonized material, then add 10 kg of kaolin and 5 kg of bentonite, spread it evenly in a mold and sinter it in stages (hold at 600 ℃ for 30 min → increase to 1300 ℃ at 3 ℃ / min and hold for 30 min) to make ceramics (compressive strength 4.1 MPa, water absorption 0.4%). Add 6% foaming agent (CaCO3:Na2SiO3=2:1) ​​to the ceramic waste and sinter at 1150 ℃ to obtain ceramsite (cylindrical compressive strength 3.2 MPa, bulk density 590 kg / m³).

[0092] Example 9

[0093] Using fine powdered gasification slag from a Shell gasifier as raw material (i.e., sample 9), the implementation steps are as follows:

[0094] (1) Fine coal gasification slag powder was prepared into a slurry with a mass concentration of 25% (average particle size of material 30 μm, no crushing required). Decarbonized material A and carbon-rich slurry (carbon content 41%) were obtained by coarse selection using a spiral chute (inclination angle 6.3°). Rich coal fuel (calorific value 1600 kcal / kg) was obtained by fine selection using a shaking table (stroke 14 mm, stroke 270 times / min, slope 2.2°). The rich coal fuel was used for coal-fired power generation; flue gas was denitrified to NOx=35 mg / m³ and preheated to 92 ℃.

[0095] (2) Combine decarburized material A and decarburized material B, mix them evenly to obtain mixed decarburized material, and then test the kaolinite phase content. The results show that the kaolinite phase content is 12%, so it can be used as a raw material for preparing ceramics and ceramsite.

[0096] (3) Take 100 kg of mixed decarburized material, then add 15 kg of kaolin and 3 kg of borax, spread it evenly in a mold and sinter it in stages (hold at 600 ℃ for 30 min → increase to 1340 ℃ at 3 ℃ / min and hold for 20 min) to make ceramics (compressive strength 4.7 MPa, water absorption 0.2%). Add 5.5% foaming agent to the ceramic waste and sinter at 1180 ℃ to obtain ceramsite (cylindrical compressive strength 4.0 MPa, bulk density 510 kg / m³).

[0097] Figure 3 This is a graph showing the 28-day compressive strength of the cement mortar samples obtained in Examples 2 to 7 above. Figure 3 It can be seen that the minimum compressive strength of the mortar product sample is 20.3 MPa, and the maximum compressive strength can reach 22.5 MPa, which meets the requirement of ≥20 MPa for the 28-day compressive strength of various mortars used in construction.

[0098] Table 2 shows the beneficial effects of the gasification slag samples of Examples 1 to 9 on the performance improvement of foam ceramics, lightweight ceramsite, and cement mortar obtained after processing with the process steps of the present invention, compared with the existing process.

[0099] Table 2

[0100] product Performance parameters Existing processes The process of this invention Improved results foam ceramics compressive strength ≤3.0 MPa ≥4.0 MPa Mechanical properties improved by 33% Lightweight ceramsite Cylinder compressive strength ≤2.1 MPa ≥3.0 MPa Load-bearing capacity increased by 43% cement mortar compressive strength ≤10 MPa ≥20 MPa Load-bearing capacity increased by 50%

[0101] As shown in Table 2, compared with the existing technology CN118893074A, the specific surface area of ​​the carbon-rich pyrolysis material obtained is no less than 500 m² / kg, which is more than double that of the carbon-rich pyrolysis material obtained by the technology in CN118893074A. Meanwhile, the use of a three-stage gradient magnetic separation technique enables an iron recovery rate of over 65%.

[0102] In the process steps of this invention, a specific combination of a spiral chute inclination angle of 5°~8° and a shaking table slope of 0.5°~4° is used, resulting in a calorific value of ≥1000 kcal / kg for the sorted rich coal fuel, and a 40% increase in carbon sorting efficiency compared to conventional settings. Furthermore, a stepped sintering process is applied to the obtained carbon-rich material (heating to 600°C at a rate of 5°C / min, then to 1250~1350°C at a rate of 3°C / min, and holding for 10 min~60 min). This ensures that the coefficient of thermal expansion of the material remains within an ideal range during the ceramic crystallization process, resulting in a dense ceramic structure and a compressive strength that increases from no more than 3.0 MPa to 4.0 MPa compared to existing processes, significantly improving product performance.

[0103] The process design of this invention fully embodies the concept of full-process resource utilization and zero waste emission, namely: rich coal fuel is used for coal blending + flue gas waste heat preheating + ceramic ceramsite production + mortar preparation (iron components are recovered as necessary), thereby achieving zero waste emission and thus the resource utilization rate reaches more than 97%, which is far higher than the highest utilization rate of 85% of existing processes.

[0104] Furthermore, using the process steps of this invention, the NOx content in the flue gas after SCR denitrification is no higher than 42 mg / m³ (GB13223-2011); the heavy metal leaching content in the tailings is: Pb 0.15 mg / L (standard limit 5 mg / L), Cr 0.08 mg / L (limit 1.5 mg / L), which is far lower than the limits specified in GB 5085.3-2007, and there is no acidic wastewater discharge. Moreover, the overall process energy consumption of this invention is reduced by 35% compared with the prior art, and the annual CO2 emission reduction is 8.5 million tons, which has significant environmental benefits and broad industrial application prospects.

[0105] The above embodiments are merely some exemplary embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A comprehensive utilization process for ultrafine pulverization of coal gasification slag with zero waste emission, comprising the following steps: S1. Depending on the source and particle size, coal gasification slag may be crushed or not crushed to convert it into coal gasification slag ultrafine powder with a particle size of <1 mm. S2. The ultrafine powder of coal gasification slag obtained in S1 is formulated into a slurry with a mass concentration of 15%~25%. The slurry is coarsely separated by a spiral chute to separate decarbonized material A and carbon-rich slurry with a carbon content ≥35%. The carbon-rich slurry is further finely selected by a shaking table to obtain decarbonized material B and rich coal fuel with a calorific value ≥1500 kcal / kg. The rich coal fuel is used for coal-fired power generation. S3. Mix the decarburized material A and decarburized material B obtained in S2 to obtain a decarburized material mixture. Then, perform kaolinite phase detection and analysis on the decarburized material mixture. If the kaolinite phase content of the decarburized material is >10%, then select S31 and S32 for further processing. S31. Take 100 parts of the decarburized material mixture according to the mass ratio, add 3-5 parts of binder and an appropriate amount of flux, and then ball mill the resulting mixture; then spread the mixture in a mold and heat it to 1250~1350 ℃, hold it for 10~60 min and sinter it to obtain foam ceramic with compressive strength ≥4.0 MPa and water absorption ≤0.5%; S32. Using the waste generated in the foam ceramic preparation process in step 31 as raw material, a certain amount of foaming agent, co-solvent and binder are added. After being mixed evenly by mechanical ball milling, the mixture is first pre-fired at a certain temperature, and then sintered at 1100~1200℃ for 60 min to obtain lightweight ceramic particles with a compressive strength ≥3.0 MPa and a bulk density ≤600 kg / m³. The decarburized material A and decarburized material B obtained from S2 are mixed to obtain a decarburized material mixture. Then, the decarburized material mixture is subjected to kaolinite phase detection and analysis. If the kaolinite phase content of the decarburized material is ≤10%, then S31(a) or S31(a) and S32(a) are selected for further processing. S31(a) Detect the iron content in the decarbonized material mixture. If the Fe content in the decarbonized material mixture is ≤1%, take 100 parts of the decarbonized material mixture and add 30%~50% cement, 5%~10% gypsum and 0.1%~5% additives according to the mass fraction. Mix evenly to obtain different types of building mortar. If the Fe content in the decarbonized material mixture is >1%, proceed to step 32(a) for further processing. S32(a) The decarbonized material mixture is separated by a magnetic separator to obtain iron-rich concentrate with an Fe content ≥30% and non-magnetic tailings; using the non-magnetic tailings as raw material, 30%~50% cement, 5%~10% gypsum and 0.1%~5% additives are added in a mass ratio, and after being mixed evenly, different types of building mortar are prepared; the iron-rich concentrate is used as an auxiliary material for iron and steel smelting.

2. The comprehensive utilization process according to claim 1, characterized in that: In step 2, the lateral tilt angle of the spiral chute is set to 5.5°~6.5°; the lateral slope of the shaking table is set to 1.5°~2.5°, the stroke is 8~25 mm, and the stroke rate is 180~320 times / min.

3. The comprehensive utilization process according to claim 1, characterized in that: Step 2 also includes a step of recovering and utilizing the heat from power generation and pyrolysis flue gas after SCR denitrification to NOx≤50 mg / m³.

4. The comprehensive utilization process according to claim 1, characterized in that: In step 31, during the preparation of foam ceramics, the temperature of the ceramic sintering holding stage is 1250 ℃~1350 ℃, and the holding time is 10 min~60 min.

5. The comprehensive utilization process according to claim 1, characterized in that: In step 31 or 32, the binder is at least one of bentonite, clay, and borax.

6. The comprehensive utilization process according to claim 1, characterized in that: The foaming agent mentioned in step 32 is a calcium carbonate and sodium silicate composite with a mass ratio of 2:

1.

7. The comprehensive utilization process according to claim 8, characterized in that: The foaming agent contains calcium carbonate with a particle size ≤10μm and sodium silicate with a modulus of 2.4~2.

6.

8. The comprehensive utilization process according to claim 1, characterized in that: In step 31, the programmed temperature rise is to raise the temperature to 600 ℃ at a rate of 5 ℃ / min and hold it for 30 min, and then raise the temperature to 1250~1350 ℃ at a rate of 3 ℃ / min.

9. The comprehensive utilization process according to claim 1, characterized in that: The SiO2 / Al2O3 molar ratio in the raw materials for preparing building mortar described in steps 31(a) and 32(a) is 2.0~2.5; and the 28-day compressive strength of the building mortar is ≥20MPa.

10. The comprehensive utilization process according to claim 1, characterized in that: The SiO2 / Al2O3 molar ratio in the non-magnetic tailings obtained after magnetic separation in step 32(a) is 2.0~2.5.

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