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CN-121990780-A - Method for preparing pozzolanic mixed material by two-step activation of illite shale

CN121990780ACN 121990780 ACN121990780 ACN 121990780ACN-121990780-A

Abstract

The invention discloses a method for preparing a pozzolanic mixed material by two-step activation of illite shale, and belongs to the technical field of building materials. The method comprises the following steps of 1) drying illite shale to remove physically adsorbed water, 2) grinding to a specified fineness, 3) carrying out thermal activation treatment at 600-1000 ℃, and 4) carrying out mechanochemical activation on a thermally activated material to ensure that the particle size distribution of a product meets D 50 to 10 mu m, D 90 is 10 to 30 mu m and the specific surface area is 1000-1600m < 2 >/kg. Aiming at the characteristic of stable illite shale structure, the invention combines high-temperature thermal activation with mechanochemical activation of specific equipment to synergistically destroy the illite crystal structure, so that the amorphous phase content of the product is more than or equal to 40 percent, and the 28d activity index is more than or equal to 80 percent. Compared with single mechanical activation, the invention greatly shortens the mechanical activation time, greatly reduces the power consumption of the system, is beneficial to realizing large-scale production, and the prepared pozzolanic mixed material can replace 30-40% of cement clinker, thereby providing a new path for carbon emission reduction in the cement industry.

Inventors

  • LI XIAOYAN
  • JIA CHI

Assignees

  • 河北工业大学

Dates

Publication Date
20260508
Application Date
20260313

Claims (10)

  1. 1. The method for preparing the pozzolanic mixed material by two-step activation of illite shale is characterized by comprising the following steps of: 1) Stoving, namely stoving illite shale and removing physically adsorbed water; 2) Grinding, namely grinding the dried illite shale to a specified fineness; 3) Heat activation, namely placing the raw material treated in the step 2) into heat activation equipment, and performing heat activation treatment at the temperature of 600-1000 o ℃; 4) Mechanochemical activation, namely mechanochemical activation is carried out on the material after thermal activation, and the mechanochemical activation adopts a dry horizontal stirring mill or a dry drum ball mill, so that the particle size distribution of the product meets the requirements that D 50 is 2-10 mu m, D 90 is 10-30 mu m, and the specific surface area is 1000-1600m2/kg, and the pozzolanic mixed material is obtained.
  2. 2. The method for preparing the pozzolanic mixed material by two-step activation of illite shale according to claim 1, wherein the illite content in the illite shale is more than or equal to 45%, the total amount of SiO 2 and Al 2 O 3 is more than or equal to 70%, and the alkali equivalent (Na 2 Oeq）≤4%,SO 3 content is less than or equal to 3.5%).
  3. 3. The method for preparing a pozzolanic blend material by two-step activation of illite shale according to claim 1, wherein in the step 3), the thermal activation temperature is 800-950 o C.
  4. 4. The method for preparing the pozzolanic mixed material by two-step activation of illite shale according to claim 1, wherein in the step 3), the heat activation equipment is a rotary kiln or a suspension calcination system.
  5. 5. The method for preparing the pozzolanic mixed material by two-step activation of illite shale according to claim 4, wherein the suspension calcination system comprises a preheating system, a calciner and a cooling system which are connected in sequence and are used for realizing preheating, partial activation and cooling of materials.
  6. 6. The method for preparing the pozzolanic mixed material by two-step activation of illite shale according to claim 1, wherein in the step 4), the mechanochemical activation is performed by adopting a dry horizontal stirring mill, and the technological parameters of the method are that the energy input density is 60-350kW/m < 3 >, the ball-to-material ratio is 10-20, the rotating speed is 300-500rpm, and the activation time is 15-30min.
  7. 7. The method for preparing the pozzolanic mixed material by two-step activation of illite shale according to claim 1, wherein in the step 4), the mechanochemical activation is performed by adopting a dry drum ball mill, and the technological parameters of the method are that the energy input density is 20-60kW/m < 3 >, the ball-material ratio is 5-15, the rotating speed is 15-25rpm, and the activation time is 120-240min.
  8. 8. The method for preparing the pozzolanic mixed material by two-step activation of illite shale according to claim 1, wherein the illite crystal structure is destroyed and the amorphous phase content is more than or equal to 40% in the material obtained in the step 4).
  9. 9. The method for preparing the pozzolanic mixed material by two-step activation of illite shale according to claim 1, wherein the pozzolanic property of the material obtained in the step 4) is qualified, and the 28d activity index is more than or equal to 80%.
  10. 10. Use of a pozzolanic blend material prepared according to the method of any one of claims 1-9 in cement or concrete.

Description

Method for preparing pozzolanic mixed material by two-step activation of illite shale Technical Field The invention belongs to the technical field of building materials, and particularly relates to a method for preparing a pozzolanic mixed material by two-step activation of illite shale. Background Pozzolanic materials are classified into natural pozzolanic mixed materials and artificial pozzolanic mixed materials according to their causes. The artificial pozzolanic mixed material comprises coal gangue, shale, clay, cinder, siliceous slag and the like. The clay raw materials which are suitable for calcination have higher activity, and are considered as the most promising mixed materials. The layered clay mineral accounts for about 21.5% of the weight of the crust, wherein the low-swelling 2:1 clay mineral represented by illite and mica is most abundant accounting for 7.7%, the 1:1 clay mineral represented by kaolinite and serpentine accounts for 5.7%, the 2:1:1 clay mineral represented by chlorite accounts for 5.1%, and the high-swelling 2:1 clay mineral represented by montmorillonite accounts for only 3.0%. The 1:1 layered structure of kaolinite is relatively loose, and is generally dehydroxylated to form metakaolinite at 400-600 ℃, i.e. kaolin is easily converted into metakaolin by thermal activation, so that high pozzolanic activity is obtained, and the metakaolinite can be used as a cement mixing material. The preparation of mixed materials by calcining kaolin using a rotary kiln or a suspension calcination process has been known in the art. Illite is a 2:1 clay mineral, and the shale, clay and waste which are rich in illite are huge in reserves, so that the development of a method for preparing a pozzolanic mixed material by activating illite shale is very necessary. In the prior art, the activation method of clay aiming at illite as main mineral comprises single thermal activation, single mechanical activation and thermal-mechanical combined activation, but has the following defects: 1) And (3) single thermal activation, wherein although the thermal activation treatment can realize the dehydroxylation and a certain degree of amorphization of illite, the obtained product has lower activity, has very limited thermal activation effect and can not meet the use requirements of the cement industry. 2) Single mechanical activation, namely mechanochemical activation treatment is expected to achieve the aim of mineral activation while reducing the particle size of minerals. For illite with stable structure, a drum ball mill is adopted, the crystal structure can be destroyed by grinding for a plurality of hours, the ideal amorphization degree is achieved, the activity is improved, and the industrial production cannot be realized due to extremely high energy consumption. The dry horizontal stirring mill is adopted, although the time is shorter than that of a roller ball mill, the energy input density of the stirring mill is extremely high, the electricity consumption is also high, the operation cost is high, and the equipment temperature rise is difficult to control. A great number of experiments are carried out on illite shale raw materials by adopting a planetary ball mill, various key parameters are widely regulated, and a product with high activity cannot be obtained all the time. 3) Thermo-mechanical co-activation the thermo-mechanical co-activation methods of the presently known clays tend to employ lower thermal activation temperatures of less than 600 ℃, preferably less than 500 ℃. This low temperature strategy may be effective for kaolinite, but for illite shale, the burden of subsequent mechanical activation remains heavy due to failure to provide sufficient thermal energy to overcome its interlaminar bond energy, failing to achieve significant energy savings and high active yields. Therefore, aiming at the specific difficult-to-activate raw material of illite shale, how to break through the limitation of the prior mechanical activation technology that the energy consumption is too high, a preparation method which can thoroughly destroy the crystal structure of illite to obtain high volcanic ash active material, can obviously reduce the energy consumption and the cost is developed, and the preparation method is a technical problem to be solved currently. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a method for preparing a pozzolanic mixed material by two-step activation of illite shale, and provides a two-step process of high-temperature heat activation pretreatment combined with moderate mechanochemical activation, and finally higher activity is realized by coupling action of heat activation and mechanochemical activation, and low-cost large-scale production can be realized. Accordingly, it is an object of the present invention to provide a method for preparing a pozzolanic blend material by activating illite shale, comprising the specific steps of: 1) Stovin