Method for preparing pozzolanic mixed material through two-step activation of illite shale

Abstract

The invention discloses a method for preparing a pozzolanic mixed material through two-step activation of illite shale, and belongs to the technical field of building materials. The method comprises the following steps: 1) drying illite shale to remove physical adsorption water; (2) grinding to specified fineness; 3) carrying out thermal activation treatment at the temperature of 600-1000 DEG C; and 4) carrying out mechanochemical activation on the thermally activated material, so that the particle size distribution of the product meets the conditions that D50 is 2-10 [mu] m and D90 is 10-30 [mu] m, and the specific surface area is 1000-1600 m / kg. Aiming at the characteristic of stable structure of illite shale, high-temperature thermal activation and mechanochemical activation of specific equipment are coupled to cooperatively destroy the crystal structure of illite, so that the amorphous phase content of the product is more than or equal to 40%, and the 28d activity index is more than or equal to 80%. Compared with single mechanical activation, the method has the advantages that the mechanical activation time is greatly shortened, the system power consumption is greatly reduced, large-scale production is facilitated, the prepared pozzolanic mixed material can replace 30-40% of cement clinker, and a new path is provided for carbon emission reduction in the cement industry.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a method for preparing volcanic ash composite materials through two-step activation of illite shale. Background Technology

[0002] Volcanic ash materials are classified into natural volcanic ash mixtures and artificial volcanic ash mixtures based on their origin. Artificial volcanic ash mixtures include coal gangue, shale, clay, coal slag, and siliceous slag. Suitable clayey raw materials exhibit high activity after calcination and are considered one of the most promising types of mixtures. Layered clay minerals constitute approximately 21.5% of the Earth's crust by weight. Among them, low-swelling 2:1 type clay minerals, represented by illite and mica, are the most abundant, accounting for 7.7%; 1:1 type clay minerals, represented by kaolinite and serpentine, account for 5.7%; 2:1:1 type clay minerals, represented by chlorite, account for 5.1%; and high-swelling 2:1 type clay minerals, represented by montmorillonite, account for only 3.0%.

[0003] Kaolinite's 1:1 layered structure is relatively loose. It typically undergoes dehydroxylation at 400-600℃ to form metakaolinite, meaning kaolinite can easily transform into metakaolinite through thermal activation, thus achieving high pozzolanic activity and making it suitable for use as a cement admixture. Technologies for preparing admixtures using rotary kilns or suspension calcination processes for kaolinite calcination already exist. Illite is a 2:1 type clay mineral, and there are vast reserves of illite-rich shale, clay, and waste materials. Therefore, developing a method to activate illite shale to prepare pozzolanic admixtures is essential.

[0004] Existing technologies for activating clays with illite as the main mineral include single thermal activation, single mechanical activation, and combined thermo-mechanical activation, but these methods have the following drawbacks:

[0005] 1) Single thermal activation: Although thermal activation can achieve the dehydroxylation of illite and a certain degree of amorphization, the resulting product has low activity and the thermal activation effect is very limited, which cannot meet the requirements of the cement industry.

[0006] 2) Single Mechanical Activation: Mechanochemical activation treatment can reduce mineral particle size while achieving mineral activation. For structurally stable illite, grinding with a drum ball mill typically requires several hours to break down the crystal structure and achieve the desired amorphization to improve activity. The extremely high energy consumption prevents industrial-scale production. While dry horizontal stirred mills offer shorter processing times than drum ball mills, their extremely high energy input density leads to high electricity consumption, high operating costs, and difficulty in controlling equipment temperature rise. Extensive experiments using planetary ball mills on illite shale raw materials, with extensive adjustments to various key parameters, have consistently failed to yield highly active products.

[0007] 3) Combined thermo-mechanical activation: Currently known methods for combined thermo-mechanical activation of clay tend to use temperatures below 600℃, preferably below 500℃. This low-temperature strategy may be effective for kaolinite, but for illite shale, the lack of sufficient thermal energy to overcome its interlayer bond energy means that the subsequent mechanical activation remains a heavy burden, failing to achieve significant energy-saving effects and high-activity output.

[0008] Therefore, for illite shale, a specific and difficult-to-activate raw material, how to overcome the limitation of excessive energy consumption in existing mechanical activation technology and develop a preparation method that can completely destroy the illite crystal structure to obtain highly active volcanic ash materials while significantly reducing energy consumption and costs is a technical problem that urgently needs to be solved. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention proposes a two-step activation method for preparing volcanic ash composite materials from illite shale. The method combines high-temperature thermal activation pretreatment with moderate mechanochemical activation in a two-step process. Through the coupling effect of thermal activation and mechanochemical activation, high activity is ultimately achieved, and low-cost large-scale production can be realized.

[0010] Therefore, one of the objectives of this invention is to provide a method for preparing volcanic ash composite materials by activating illite shale, comprising the following specific steps: 1) Drying: Dry the illite shale to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale to the specified fineness; 3) Thermal activation: Place the raw material treated in step 2) into a thermal activation device and heat it at 600-1000°C. o Thermal activation treatment is performed at a temperature of C. 4) Mechanochemical activation: The thermally activated material is subjected to mechanochemical activation using a dry horizontal stirred mill or a dry drum ball mill to ensure that the product particle size distribution meets the requirements of D. 50 2-10μm and D 90 With a particle size of 10-30 μm and a specific surface area of ​​1000-1600 m² / kg, a volcanic ash-based mixed material was obtained.

[0011] As a preferred technical solution, the illite shale contains ≥45% illite, ≥70% total SiO2 and Al2O3, ≤4% alkali equivalent (Na2Oeq), and ≤3.5% SO3.

[0012] As a preferred technical solution, in step 3), the thermal activation temperature is 800-950°C. o C.

[0013] As a preferred technical solution, in step 3), the thermal activation equipment is a rotary kiln or a suspension calcination system.

[0014] As a preferred technical solution, the suspension calcination system includes a preheating system, a calcination furnace, and a cooling system connected in sequence, used to achieve preheating, partial activation, and cooling of the material.

[0015] As a preferred technical solution, in step 4), a dry horizontal stirred mill is used for mechanical and chemical activation, and the process parameters meet the following requirements: energy input density of 60-350kW / m³, ball-to-material ratio of 10-20, rotation speed of 300-500rpm, and activation time of 15-30min.

[0016] As a preferred technical solution, in step 4), a dry roller ball mill is used for mechanochemical activation, and the process parameters meet the following requirements: energy input density of 20-60kW / m³, ball-to-material ratio of 5-15, rotation speed of 15-25rpm, and activation time of 120-240min.

[0017] As a preferred technical solution, in the material obtained in step 4), the illite crystal structure is destroyed and the content of amorphous phase is ≥40%.

[0018] As a preferred technical solution, the pozzolanic properties of the material obtained in step 4) are qualified, and the 28-day activity index is ≥80%.

[0019] The present invention also discloses the application of the pozzolanic composite material prepared by the above method in cement or concrete.

[0020] The core innovations of this invention include: (1) Based on the thermal activation treatment, the amorphization of illite mineral and the full utilization of its activity were achieved through mechanical and chemical activation treatment, which greatly improved the activity index of the product.

[0021] (2) When extending the ball milling time of the planetary ball mill and adjusting the operating parameters could not achieve effective activation, the expected effect was finally achieved by exploring the operating parameters of the stirred mill and the drum ball mill. It was determined that the equipment for mechanochemical activation could be a dry horizontal stirred mill or a dry drum ball mill, and the selection range of parameters such as ball-to-material ratio, rotation speed, and activation time was proposed.

[0022] The advantages and positive effects of this invention are: First, through the synergistic effect of thermal activation and mechanochemical activation, the stable crystal structure of illite can be effectively disrupted, resulting in an amorphous phase content of over 40% and a 28-day activity index of over 80%, meeting the requirements for use in cement admixtures. Second, compared with a single mechanical activation process, high-temperature thermal activation pretreatment significantly shortens the mechanochemical activation time (e.g., 15-30 min for dry horizontal stirred mills and 120-240 min for dry drum ball mills), reducing system power consumption by 35-50% and significantly lowering production costs. Third, this two-step process alleviates the heat accumulation problem of high-energy mechanical activation equipment, reduces the requirements for cooling devices, and facilitates large-scale industrial production. Finally, the pozzolanic admixture prepared by this invention can replace 30-40% of cement clinker, providing a new technological path for CO2 emission reduction in the cement and concrete industry. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the two-step process for preparing volcanic ash-based mixed materials from activated illite shale, as provided by the present invention.

[0024] Figure 2 Scanning electron microscope (SEM) of illite shale; Figure 3 The image shows a scanning electron microscope (SEM) image of the product after thermal activation of illite shale, which is not much different from the microstructure of the raw material. Figure 4 The image shows a scanning electron microscope (SEM) image of the product of illite shale after further mechanochemical activation, revealing flocculent amorphous phases and secondary agglomeration of particles. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below; obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The mechanochemical activation of clay minerals is related to compression, shearing, impact, and friction during the grinding process. The type of mill is crucial for maximizing energy transfer and ensuring effective activation. Planetary ball mills are widely used from laboratory to pilot-scale operations due to their high efficiency. However, extensive experiments using planetary ball mills on illite shale raw materials, with extensive adjustments to key parameters such as milling time, feed-to-ball ratio, rotational speed, and grinding media size, have consistently failed to yield highly active products. In laboratory settings, the grinding effect of drum ball mills on illite shale was explored. Results showed that after milling times exceeding 6 hours, products with a 28-day activity index exceeding 80% could be obtained. However, a drawback is the excessively long residence time within the mill. Stirred mills grind materials through impact, shearing, and friction, with shearing and extrusion forces being more conducive to obtaining fine particles. Furthermore, stirred mills also have a dispersing effect, which is more attractive to lamellar minerals. Experiments using a stirred mill alone showed that after a reaction time exceeding 60 minutes, a product with an activity index exceeding 80% could be obtained after 28 days. However, due to the high energy input density of the stirred mill, the corresponding power consumption exceeded 300 kWh / t. Using either a drum ball mill or a stirred mill alone would directly increase product costs due to excessive power consumption, putting the company at a disadvantage in market competition.

[0027] To achieve industrial-scale production, it was decided to combine thermal activation with mechanochemical activation. Laboratory tests have demonstrated good activation results and technical and economic feasibility. This synergistic activation technology is particularly advantageous for minerals such as illite, where thermal activation is not very effective.

[0028] Therefore, this invention provides a detailed description of a two-step activation method for preparing volcanic ash composite materials from illite shale, wherein the illite shale contains ≥45% illite, ≥70% total SiO2 and Al2O3, ≤4% alkali equivalent (Na2Oeq), and ≤3.5% SO3.

[0029] Example 1 A two-step activation method for preparing volcanic ash composite materials from illite shale: 1) Drying: Dry the crushed illite shale at 100-200°C. o C. Dry until moisture content is less than 1% to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale until the residue on an 80μm square mesh sieve is ≤10%; 3) Thermal activation: Heat the raw materials treated in step 2) at 800-900°C. o C is used for thermal activation. The thermal activation equipment is a rotary kiln, and the material residence time in the kiln is 60 minutes. 4) Mechanochemical activation: The thermally activated material obtained in step 3) is subjected to mechanochemical activation. The mechanical activation equipment adopts a dry horizontal stirred mill with an energy input density of 250kW / m³. 3 The ball-to-material ratio was 10, the rotation speed was set to 400 rpm, and the activation time was 15 min. 5) Material performance testing: The particle size distribution of the activated material obtained in step 4) satisfies D 50 At 2.8μm and D 90 At 15.0 μm, the specific surface area is 1246 m². 2 / kg; amorphous phase content 43.5%; pozzolanic properties qualified; when 30% of the activated material obtained in step 4) is compounded with 70% cement, under the standard conditions of water-cement ratio of 0.5 and mortar mix ratio of 1:3, the activity index after 28 days is 80.1%.

[0030] Example 2 A two-step activation method for preparing volcanic ash composite materials from illite shale: 1) Drying: Dry the crushed illite shale at 100-200°C. o C. Dry until moisture content is less than 1% to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale until the residue on an 80μm square mesh sieve is ≤10%; 3) Thermal activation: Heat the raw materials treated in step 2) at 900-950°C. o C is used for thermal activation. The thermal activation equipment is a rotary kiln, and the material residence time in the kiln is 30 minutes. 4) Mechanochemical activation: The thermally activated material obtained in step 3) is subjected to mechanochemical activation. The mechanical activation equipment adopts a dry horizontal stirred mill with an energy input density of 350kW / m³. 3 The ball-to-material ratio was 18, the rotation speed was set to 450 rpm, and the activation time was 30 min; 5) Material performance testing: The particle size distribution of the activated material obtained in step 4) satisfies D 50 At 3.5μm and D 90 At 17.2 μm, the specific surface area is 1438 m². 2 / kg; amorphous phase content 49.2%; pozzolanic properties qualified; when 30% of the activated material obtained in step 4) is compounded with 70% cement, under the standard conditions of water-cement ratio of 0.5 and mortar mix ratio of 1:3, the activity index after 28 days is 87.4%.

[0031] Example 3 A two-step activation method for preparing volcanic ash composite materials from illite shale: 1) Drying: Dry the crushed illite shale at 100-200°C. oC. Dry until moisture content is less than 1% to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale until the residue on an 80μm square mesh sieve is ≤10%; 3) Thermal activation: Heat the raw materials treated in step 2) at 800-850°C. o C is used for thermal activation, and the thermal activation equipment is a suspension calcination system, with a material calcination time of 12 seconds; 4) Mechanochemical activation: The thermally activated material obtained in step 3) is subjected to mechanochemical activation. The mechanical activation equipment adopts a dry horizontal stirred mill with an energy input density of 60kW / m³. 3 The ball-to-material ratio was 15, the rotation speed was set to 500 rpm, and the activation time was 20 min. 5) Material performance testing: The particle size distribution of the activated material obtained in step 4) satisfies D 50 At 3.7μm and D 90 At 28.7 μm, the specific surface area is 1264 m². 2 / kg; amorphous phase content 40.1%; pozzolanic properties qualified; when 30% of the activated material obtained in step 4) is compounded with 70% cement, under the standard conditions of water-cement ratio of 0.5 and mortar mix ratio of 1:3, the activity index after 28 days is 82.7%.

[0032] The suspension calcination system of this invention includes a preheating system, a calcination furnace, and a cooling system connected in sequence to achieve preheating, partial activation, and cooling functions. The preheating system typically consists of four to six stages of cyclones, and the cooling system consists of two to four stages of cyclones. The ground material first enters the first-stage cyclone of the preheating system. After being preheated by multiple stages of cyclones, it enters the calcination furnace. The partially activated material leaves the calcination furnace and enters the final-stage cyclone of the preheating system. The material separated by the final-stage cyclone of the preheating system enters the first-stage cyclone of the cooling system. The material collected by the final-stage cyclone of the cooling system can then proceed to the subsequent mechanochemical activation process.

[0033] Example 4 A two-step activation method for preparing volcanic ash composite materials from illite shale: 1) Drying: Dry the crushed illite shale at 100-200°C. o C. Dry until moisture content is less than 1% to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale until the residue on an 80μm square mesh sieve is ≤10%; 3) Thermal activation: Heat the raw materials treated in step 2) at 850-900°C. o C is used for thermal activation, and the thermal activation equipment is a suspension calcination system, with a material calcination time of 25 seconds; 4) Mechanochemical activation: The thermally activated material obtained in step 3) is subjected to mechanochemical activation. The mechanical activation equipment adopts a dry horizontal stirred mill with an energy input density of 150kW / m³. 3 The ball-to-material ratio was 20, the rotation speed was set to 300 rpm, and the activation time was 30 min; 5) Material performance testing: The particle size distribution of the activated material obtained in step 4) satisfies D 50 At 2.6μm and D 90 At 12.9 μm, the specific surface area is 1521 m². 2 / kg; amorphous phase content 40.9%; pozzolanic properties qualified; when 30% of the activated material obtained in step 4) is compounded with 70% cement, under the standard conditions of water-cement ratio of 0.5 and mortar mix ratio of 1:3, the activity index after 28 days is 85.5%.

[0034] Comparative Example 5 A method for preparing volcanic ash composite materials from illite shale through mechanical activation only: 1) Drying: Dry the crushed illite shale at 100-200°C. o C. Dry until moisture content is less than 1% to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale until the residue on an 80μm square mesh sieve is ≤10%; 3) Mechanochemical activation: The raw materials treated in step 2) are directly subjected to mechanochemical activation. The mechanical activation equipment adopts a dry horizontal stirred mill with an energy input density of 300kW / m³. 3 The ball-to-material ratio was 15, the rotation speed was set to 350 rpm, and the activation time was 60 min. 4) Material performance testing: The particle size distribution of the activated material obtained in step 3) satisfies D 50 At 2.3μm and D 90 At 11.9 μm, the specific surface area is 1328 m². 2 / kg; amorphous phase content 41.3%; pozzolanic properties qualified; when 30% of the activated material obtained in step 3) is mixed with 70% cement, under the standard conditions of water-cement ratio of 0.5 and mortar mix ratio of 1:3, the activity index after 28 days is 84.7%.

[0035] Comparative Example 6 A method for preparing volcanic ash composite materials from illite shale through mechanical activation only: 1) Drying: Dry the crushed illite shale at 100-200°C. o C. Dry until moisture content is less than 1% to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale until the residue on an 80μm square mesh sieve is ≤10%; 3) Mechanochemical activation: The raw materials treated in step 2) are directly subjected to mechanochemical activation. The mechanical activation equipment adopts a dry horizontal stirred mill with an energy input density of 200kW / m³. 3 The ball-to-material ratio was 15, the rotation speed was set to 500 rpm, and the activation time was 120 min. 4) Material performance testing: The particle size distribution of the activated material obtained in step 3) satisfies D 50 At 2.3μm and D 90 At 11.9 μm, the specific surface area is 1328 m². 2 / kg; amorphous phase content 40.5%; pozzolanic properties qualified; when 30% of the activated material obtained in step 3) is compounded with 70% cement, under the standard conditions of water-cement ratio of 0.5 and mortar mix ratio of 1:3, the activity index after 28 days is 83.9%.

[0036] Example 7 A two-step activation method for preparing volcanic ash composite materials from illite shale: 1) Drying: Dry the crushed illite shale at 100-200°C. o C. Dry until moisture content is less than 1% to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale until the residue on an 80μm square mesh sieve is ≤10%; 3) Thermal activation: Heat the raw materials treated in step 2) at 800-900°C. o C is used for thermal activation. The thermal activation equipment is a rotary kiln, and the material residence time in the kiln is 40 minutes. 4) Mechanochemical activation: The thermally activated material obtained in step 3) is subjected to mechanochemical activation. The mechanical activation equipment is a dry drum ball mill with an energy input density of 60 kW / m³. 3 The ball-to-material ratio was 10, the rotation speed was set to 15 rpm, and the activation time was 240 min; 5) Material performance testing: The particle size distribution of the activated material obtained in step 4) satisfies D 50 At 2.2μm and D 90 At 10.1 μm, the specific surface area is 1496 m². 2 / kg; amorphous phase content 44.7%; pozzolanic properties qualified; when 30% of the activated material obtained in step 4) is compounded with 70% cement, under the standard conditions of water-cement ratio of 0.5 and mortar mix ratio of 1:3, the activity index after 28 days is 83.7%.

[0037] Example 8 A two-step activation method for preparing volcanic ash composite materials from illite shale: 1) Drying: Dry the crushed illite shale at 100-200°C. oC. Dry until moisture content is less than 1% to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale until the residue on an 80μm square mesh sieve is ≤10%; 3) Thermal activation: Heat the raw materials treated in step 2) at 900-950°C. o C is used for thermal activation. The thermal activation equipment is a suspension calcination system, and the calcination time of the material is 15 seconds. 4) Mechanochemical activation: The thermally activated material obtained in step 3) is subjected to mechanochemical activation. The mechanical activation equipment is a dry drum ball mill with an energy input density of 20kW / m³. 3 The ball-to-material ratio was 10, the rotation speed was set to 20 rpm, and the activation time was 120 min; 5) Material performance testing: The particle size distribution of the activated material obtained in step 4) satisfies D 50 At 2.9μm and D 90 At 13.1 μm, the specific surface area is 1319 m². 2 / kg; amorphous phase content 40.1%; pozzolanic properties qualified; when 30% of the activated material obtained in step 4) is compounded with 70% cement, under the standard conditions of water-cement ratio of 0.5 and mortar mix ratio of 1:3, the activity index after 28 days is 80.5%.

[0038] Comparative Example 9 A method for preparing volcanic ash composite materials from illite shale through mechanical activation only: 1) Drying: Dry the crushed illite shale at 100-200°C. o C. Dry until moisture content is less than 1% to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale until the residue on an 80μm square mesh sieve is ≤10%; 3) Mechanochemical activation: The material obtained in step 2) is directly subjected to mechanochemical activation. The mechanical activation equipment is a dry drum ball mill with an energy input density of 40 kW / m³. 3 The ball-to-material ratio was 10, the rotation speed was set to 25 rpm, and the activation time was 360 min; 4) Material performance testing: The particle size distribution of the activated material obtained in step 3) satisfies D 50 At 2.4μm and D 90 At 14.1 μm, the specific surface area is 1293 m². 2 / kg; amorphous phase content 38.5%; pozzolanic properties qualified; when 30% of the activated material obtained in step 3) is compounded with 70% cement, under the standard conditions of water-cement ratio of 0.5 and mortar mix ratio of 1:3, the activity index after 28 days is 67.3%.

[0039] Comparative Example 10 A method for preparing volcanic ash composite materials from illite shale through mechanical activation only: 1) Drying: Dry the crushed illite shale at 100-200°C. o C. Dry until moisture content is less than 1% to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale until the residue on an 80μm square mesh sieve is ≤10%; 3) Mechanochemical activation: The material obtained in step 2) is directly subjected to mechanochemical activation. The mechanical activation equipment is a dry drum ball mill with an energy input density of 60 kW / m³. 3 The ball-to-material ratio was 10, the rotation speed was set to 18 rpm, and the activation time was 480 min; 4) Material performance testing: The particle size distribution of the activated material obtained in step 3) satisfies D 50 At 2.1μm and D 90 At 10.3 μm, the specific surface area is 1584 m². 2 / kg; amorphous phase content 42.6%; pozzolanic properties qualified; when 30% of the activated material obtained in step 3) is compounded with 70% cement, under the standard conditions of water-cement ratio of 0.5 and mortar mix ratio of 1:3, the activity index after 28 days is 81.6%.

[0040] Comparative Example 11 A method for preparing volcanic ash composite materials from illite shale through thermal activation only: 1) Drying: Dry the crushed illite shale at 100-200°C. o C. Dry until moisture content is less than 1% to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale until the residue on an 80μm square mesh sieve is ≤10%; 3) Thermal activation: Heat the raw materials treated in step 2) at 800-900°C. o C is used for thermal activation, and the thermal activation equipment is a suspension calcination system, with a material calcination time of 20 seconds; 4) Grinding: Grind the thermally activated material obtained in step 3) using a planetary ball mill for 30 minutes. 5) Material performance testing: The particle size distribution of the activated material obtained in step 4) satisfies D 50 At 3.4μm and D 90 At 13.0 μm, the specific surface area is 1319 m². 2 / kg; amorphous phase content 12.3%; pozzolanic properties qualified; when 30% of the activated material obtained in step 4) is compounded with 70% cement, under the standard conditions of water-cement ratio of 0.5 and mortar mix ratio of 1:3, the activity index after 28 days is 58.4%.

[0041] Comparative Example 12 A method for preparing volcanic ash composite materials from illite shale through thermal activation only: 1) Drying: Dry the crushed illite shale at 100-200°C. o C. Dry until moisture content is less than 1% to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale until the residue on an 80μm square mesh sieve is ≤10%; 3) Thermal activation: Heat the raw materials treated in step 2) at 900-950°C. o C is used for thermal activation. The thermal activation equipment is a rotary kiln, and the residence time of the material in the kiln is 45 minutes. 4) Grinding: Grind the thermally activated material obtained in step 3) using a planetary ball mill for 30 minutes. 5) Material performance testing: The particle size distribution of the activated material obtained in step 4) satisfies D 50 At 4.1μm and D 90 At 21.8 μm, the specific surface area is 1267 m². 2 / kg; amorphous phase content 7.4%; pozzolanic properties qualified; when 30% of the activated material obtained in step 4) is compounded with 70% cement, under the standard conditions of water-cement ratio of 0.5 and mortar mix ratio of 1:3, the activity index after 28 days is 61.3%.

[0042] Comparative Example 13 A method for preparing volcanic ash composite materials from illite shale through thermal activation only: 1) Drying: Dry the crushed illite shale at 100-200°C. o C. Dry until moisture content is less than 1% to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale until the residue on an 80μm square mesh sieve is ≤10%; 3) Thermal activation: Heat the raw materials treated in step 2) at 900-950°C. o C is used for thermal activation, and the thermal activation equipment is a suspension calcination system, with a material calcination time of 20 seconds; 4) Grinding: The thermally activated material obtained in step 3) is ground using a planetary ball mill for 360 minutes. 5) Material performance testing: The particle size distribution of the activated material obtained in step 4) satisfies D 50 At 4.7μm and D 90 At 18.9 μm, the specific surface area is 1279 m². 2 / kg; amorphous phase content 11.5%; pozzolanic properties qualified; when 30% of the activated material obtained in step 4) is compounded with 70% cement, under the standard conditions of water-cement ratio of 0.5 and mortar mix ratio of 1:3, the activity index after 28 days is 57.2%.

[0043] Comparative Example 14 A method for preparing volcanic ash composite materials from illite shale through thermal activation only: 1) Drying: Dry the crushed illite shale at 100-200°C. o C. Dry until moisture content is less than 1% to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale until the residue on an 80μm square mesh sieve is ≤10%; 3) Thermal activation: Heat the raw materials treated in step 2) at 800-900°C. o C is used for thermal activation. The thermal activation equipment is a rotary kiln, and the residence time of the material in the kiln is 45 minutes. 4) Grinding: The thermally activated material obtained in step 3) is ground using a planetary ball mill for 360 minutes. 5) Material performance testing: The particle size distribution of the activated material obtained in step 4) satisfies D 50 At 4.2μm and D 90 At 19.5 μm, the specific surface area is 1234 m². 2 / kg; amorphous phase content 7.1%; pozzolanic properties qualified; when 30% of the activated material obtained in step 4) is compounded with 70% cement, under the standard conditions of water-cement ratio of 0.5 and mortar mix ratio of 1:3, the activity index after 28 days is 60.8%.

[0044] This invention provides Examples 1-14, which experimentally tested the key parameters in steps 3) and 4), and verified the 28-day activity index of the pozzolanic mixture under the conditions of a water-cement ratio of 0.5 and a mortar-mortar mixing ratio of 1:3 after the experiments. See the table below for details: Table 1. Activation parameters and performance results of cement blends in two steps

[0045] From the above examples, it can be seen that: The mechanical activation equipment used in Examples 1-6 was a dry horizontal stirred mill. Examples 1-4 involved mechanical and chemical activation based on thermal activation (800-950℃), achieving an activity index of 80.1%-85.5% within a short time of 15-30 minutes. Example 1 achieved 80.1% activity in just 15 minutes. Examples 5-6, without thermal activation, also achieved activities exceeding 80% as the mechanical activation time was extended to 60 and 120 minutes, respectively. This demonstrates that thermal activation significantly reduces the time required for mechanical and chemical activation, thereby reducing energy consumption.

[0046] The mechanical activation equipment used in Examples 7-10 was a dry drum ball mill. Examples 7-8 involved mechanical and chemical activation based on thermal activation (temperature 800-950℃), with activation time controlled at 120-240 minutes, achieving an activity level above 80%. Examples 9-10 showed that without thermal activation, the mechanical and chemical activation time needed to be extended. In Example 9, the activity reached only 67.3% after 360 minutes of activation, while in Example 10, it only reached an activity level >80% after 480 minutes. Although different mechanical activation equipment resulted in grinding times differing by several to tens of times, thermal activation effectively shortened the mechanical activation time, demonstrating the superiority of a two-step activation process using both thermal and mechanical / chemical activation.

[0047] Of particular note is that, in Comparative Examples 11-14, which also employed thermal activation followed by planetary ball milling for 360 minutes, the 28-day activity index remained at 57.2%-61.3%, indicating that planetary ball mills are almost incapable of achieving amorphization of illite minerals. In contrast, Example 1, with a time reduced to 15 minutes, showed an activity increase of nearly 20 percentage points. This strongly demonstrates that the present invention is not merely a simple combination of "heat + machine," but rather a synergistic effect resulting from the specific combination of "specific high-temperature thermal activation" and "high-energy stirred milling." Thermal activation disrupts the layered structure of illite, while the high shear force of the stirred mill rapidly disperses and pulverizes it, achieving amorphization. Without either of these components, the technical effects of the present invention cannot be achieved.

[0048] The embodiments given above are preferred examples for implementing the present invention, and the present invention is not limited to the above embodiments. Any non-essential additions or substitutions made by those skilled in the art based on the technical features of the present invention are within the protection scope of the present invention.

Claims

1. A method for preparing volcanic ash composite materials by two-step activation of illite shale, characterized in that, Includes the following steps: 1) Drying: Dry the illite shale to remove physically adsorbed water; 2) Grinding: Grind the dried illite shale to the specified fineness; 3) Thermal activation: Place the raw material treated in step 2) into a thermal activation device and heat it at 600-1000°C. o Thermal activation treatment is performed at a temperature of C. 4) Mechanochemical activation: The thermally activated material is subjected to mechanochemical activation using a dry horizontal stirred mill or a dry drum ball mill to ensure that the product particle size distribution meets D. 50 2-10μm and D 90 With a particle size of 10-30 μm and a specific surface area of ​​1000-1600 m² / kg, a volcanic ash-based mixed material was obtained.

2. The method for preparing volcanic ash composite material by two-step activation of illite shale according to claim 1, characterized in that: The illite shale contains ≥45% illite, ≥70% total SiO2 and Al2O3, ≤4% alkali equivalent (Na2Oeq), and ≤3.5% SO3.

3. The method for preparing volcanic ash composite material by two-step activation of illite shale according to claim 1, characterized in that: In step 3), the thermal activation temperature is 800-950°C. o C.

4. The method for preparing volcanic ash composite material by two-step activation of illite shale according to claim 1, characterized in that: In step 3), the thermal activation equipment is a rotary kiln or a suspension calcination system.

5. The method for preparing volcanic ash composite material by two-step activation of illite shale according to claim 4, characterized in that: The suspension calcination system includes a preheating system, a calcination furnace, and a cooling system connected in sequence, used to preheat, partially activate, and cool the material.

6. The method for preparing volcanic ash composite material by two-step activation of illite shale according to claim 1, characterized in that: In step 4), a dry horizontal stirred mill is used for mechanical and chemical activation, and the process parameters are: energy input density of 60-350kW / m³, ball-to-material ratio of 10-20, rotation speed of 300-500rpm, and activation time of 15-30min.

7. The method for preparing volcanic ash composite material by two-step activation of illite shale according to claim 1, characterized in that: In step 4), a dry roller ball mill is used for mechanochemical activation, and the process parameters are: energy input density of 20-60kW / m³, ball-to-material ratio of 5-15, rotation speed of 15-25rpm, and activation time of 120-240min.

8. The method for preparing volcanic ash composite material by two-step activation of illite shale according to claim 1, characterized in that: In the material obtained in step 4), the illite crystal structure is destroyed and the content of amorphous phase is ≥40%.

9. The method for preparing volcanic ash composite material by two-step activation of illite shale according to claim 1, characterized in that: The pozzolanic properties of the material obtained in step 4) are qualified, and the 28-day activity index is ≥80%.

10. The use of the pozzolanic composite material prepared by the method according to any one of claims 1-9 in cement or concrete.

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