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CN-122010446-A - Method for preparing alkali-activated agent and mineral admixture by converting calcium silicate-based solid waste material

CN122010446ACN 122010446 ACN122010446 ACN 122010446ACN-122010446-A

Abstract

The invention relates to a method for preparing an alkali excitant and a mineral admixture by converting a silicon-calcium-based solid waste material, which comprises the following steps of dispersing the silicon-calcium-based solid waste material in a sodium carbonate aqueous solution, carrying out a reaction, then carrying out solid-liquid separation to obtain filtrate and solid waste residues, separating excessive sodium carbonate from the filtrate to obtain a silicon-rich high alkali solution, carrying out modulus and concentration measurement on the silicon-rich high alkali solution, regulating the molar ratio of SiO 2 and Na 2 O in the silicon-rich high alkali solution to 1.0-2.0, and obtaining a regenerated alkali excitant, wherein the solid waste is doped and dried to obtain the regenerated mineral admixture. The method can realize the conversion of the silicon-calcium-based solid waste material into the regenerated alkali excitant and the mineral admixture, and the regenerated material obtained by conversion can be used as the raw material of the cementing material, so that the high-value closed-loop utilization of the silicon-calcium-based solid waste is realized while the energy consumption and the carbon emission are reduced.

Inventors

  • YUAN QIANG
  • ZHOU XIAOFENG
  • WU JUN
  • CHEN LOU

Assignees

  • 高速铁路建造技术国家工程研究中心
  • 中国中铁股份有限公司
  • 中南大学

Dates

Publication Date
20260512
Application Date
20260310

Claims (8)

  1. 1. The method for preparing the alkali-activated agent and the mineral admixture by converting the calcium silicate-based solid waste material is characterized by comprising the following steps of: s1, dispersing a calcium silicate-based solid waste material in a sodium carbonate aqueous solution for reaction, and then carrying out solid-liquid separation to obtain filtrate and solid waste residues; s2, separating excessive sodium carbonate from the filtrate to obtain a silicon-rich high alkali solution; s3, carrying out modulus and concentration measurement on the silicon-rich high alkali solution, regulating the molar ratio of SiO 2 and Na 2 O in the silicon-rich high alkali solution to 1.0-2.0, and obtaining the regenerated alkali activator, and drying the solid waste doping to obtain the regenerated mineral admixture.
  2. 2. The method for preparing alkali-activated agent and mineral admixture by converting calcium silicate-based solid waste material according to claim 1, wherein in step S1, the concentration of the sodium carbonate aqueous solution is 1.5-3mol/L, and the solid-liquid ratio is 10-25ml/g.
  3. 3. The method for preparing alkali-activated agent and mineral admixture by converting calcium silicate-based solid waste material according to claim 1, wherein in step S1, the reaction temperature is 20-55 ℃.
  4. 4. The method for preparing alkali excitant and mineral admixture by converting waste materials based on silicon and calcium according to claim 1, wherein in step S3, the solid content of the high alkali solution rich in silicon is adjusted to 30-45wt% by concentrating the high alkali solution rich in silicon or adding siliceous material into the high alkali solution rich in silicon, so that the molar ratio of SiO 2 to Na 2 O in the high alkali solution rich in silicon is adjusted to 1.0-2.0.
  5. 5. The method for preparing alkali-activated agent and mineral admixture by converting calcium silicate-based solid waste material according to claim 4, wherein the siliceous material is at least one of silica fume and white carbon black.
  6. 6. The method for preparing alkali excitant and mineral admixture by converting silicon-calcium based solid waste materials according to claim 1, wherein in the step S2, the filtrate is heated to 40-50 ℃ to concentrate the filtrate to 1/3-1/2 of the original volume, then cooled to 20-25 ℃ for crystallization, and solid-liquid separation is carried out to obtain the silicon-rich high alkali solution.
  7. 7. The method for preparing alkali-activated agent and mineral admixture by converting silica-calcium based solid waste material according to any one of claims 1 to 6, wherein the silica-calcium based solid waste material is at least one of converter steel slag powder, circuit steel slag powder, waste concrete regenerated micro powder and cement kiln dust.
  8. 8. The method for preparing alkali-activated agent and mineral admixture by converting calcium silicate-based solid waste material according to claim 7, wherein the specific surface area of the calcium silicate-based solid waste material is 300-500m 2 /kg, and the median particle size is 5-30 μm.

Description

Method for preparing alkali-activated agent and mineral admixture by converting calcium silicate-based solid waste material Technical Field The invention relates to the technical field of solid waste resource utilization and green building materials, in particular to a method for preparing an alkali-activated agent and a mineral admixture by converting a silicon-calcium-based solid waste material. Background With the continuous promotion of infrastructure construction and urban updating, a large amount of calcium-silicon-based solid waste is generated by steel smelting and building demolition, including converter steel slag, electric furnace steel slag, waste concrete regenerated micro powder, cement kiln dust and the like. Published studies show that the CaO content in typical converter steel slag is generally greater than 35%, the SiO 2 content is generally greater than 10%, and a certain amount of free calcium oxide and free magnesium oxide are contained, so that the converter steel slag can be regarded as potential cementing material resources which are underutilized. Taking steel slag as an example, although the main crystal phase is similar to cement clinker, the steel slag is directly used as a building material and is easy to generate the problem of poor volume stability due to higher content of free calcium oxide and free magnesium oxide, and the steel slag is low in utilization rate for a long time and is mostly disposed in a piling or low added value landfill mode. The recycled aggregate prepared from the waste concrete has a certain application in engineering, but most of the recycled micro powder is hydrated calcium silicate and calcium hydroxide, so that the recycled micro powder has low activity and is often discarded. Most of the existing silicon-calcium-based solid waste utilization paths are single component extraction, and full-component high-value utilization is not fully realized. Existing processes tend to focus on extracting silica or specific metallic elements from the calcium silicate-based solid waste, but the resulting solid residue is difficult to further utilize. Meanwhile, the alkali-activated cementing material is considered to be a potential green building material system for replacing silicate cement due to low clinker consumption and excellent mechanical property. However, the current common exciting agent of the system comprises commercial sodium silicate and sodium hydroxide, the cost is high, and the commercial sodium silicate is usually prepared by melting quartz sand and sodium carbonate at a high temperature of above 1300 ℃, and the energy consumption is high and the carbon emission is enlarged. Disclosure of Invention Based on the technical problems in the prior art, the invention innovatively provides a method for preparing an alkali excitant and a mineral admixture by converting all components of calcium silicate-based solid waste, wherein calcium in solid waste materials is converted into calcium carbonate to be remained in a solid phase, silicon components and alkali generated in situ enter a liquid phase, the liquid phase is subjected to tempering and conversion into the alkali excitant, and modified solid waste residues are used as the mineral admixture for preparing the alkali excitant, so that the high-value closed-loop utilization of the calcium silicate-based solid waste is realized while the energy consumption and the carbon emission are reduced. In order to achieve the above object, the technical scheme of the present invention is as follows: A method for preparing alkali-activated agent and mineral admixture by converting calcium silicate-based solid waste material comprises the following steps: s1, dispersing a calcium silicate-based solid waste material in a sodium carbonate aqueous solution for reaction, and then carrying out solid-liquid separation to obtain filtrate and solid waste residues; s2, separating excessive sodium carbonate from the filtrate to obtain a silicon-rich high alkali solution; s3, carrying out modulus and concentration measurement on the silicon-rich high alkali solution, regulating the molar ratio of SiO 2 and Na 2 O in the silicon-rich high alkali solution to 1.0-2.0, and obtaining the regenerated alkali activator, and drying the solid waste doping to obtain the regenerated mineral admixture. The silicon-calcium-based solid waste material is rich in minerals such as tricalcium silicate, dicalcium silicate and the like, and the silicon-calcium-based solid waste material is dissolved in a sodium carbonate solution by utilizing the chemical instability property of the silicon-calcium-based solid waste in the concentrated sodium carbonate solution to obtain a silicon-rich high alkali solution. Taking simplified dicalcium silicate as an example, the main reactions occurring in sodium carbonate solutions can be summarized as 2CaO.SiO 2 (solid) +2Na 2CO3 (liquid) +H 2O→2CaCO3 (solid) +Na 2SiO3 (liquid) +2NaOH (liquid), and part of the