Carbonate Bonded Article Production via Elevated Temperature Carbonation
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Solution Overview
Problem
Existing methods for producing carbonate-bonded articles, such as those using accelerated carbonation, face limitations in achieving high compressive strength and CO2 sequestration due to restricted temperature and pressure conditions, which hinder the formation of stable carbonates and result in inadequate mechanical properties and CO2 penetration, especially in thicker materials.
Innovation Solution
A method involving the carbonation of alkaline granular materials at elevated temperatures (above 70°C) and pressures (at least 0.5 MPa) to form alkaline earth metal carbonates as the primary binding phase, with specific conditions ensuring that carbonates contribute more than 50% to the compressive strength and minimizing the formation of calcium silicate hydrates, thereby enhancing mechanical and environmental properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If low temperature (0-10°C) and low pressure (up to 0.3 MPa) are used for carbonation, then stable carbonate products are formed, but compressive strength and CO2 penetration are insufficient
Solution Approach 1:
The patent applies parameter changes by transitioning from low temperature/pressure conditions to elevated temperature (above 70°C) and pressure (at least 0.5 MPa) conditions. This enables the carbonation process to achieve both stable carbonate formation and high compressive strength (up to 65 MPa) by optimizing the reaction parameters beyond conventional limits
2Stability of the object's composition
If low temperature (0-10°C) is used for carbonation, then stable carbonates are formed, but CO2 penetration and reaction efficiency are limited
Solution Approach 1:
The patent changes the temperature parameter from low (0-10°C) to elevated (above 70°C) conditions, which significantly enhances CO2 penetration and reaction kinetics. This enables efficient CO2 sequestration while maintaining stable carbonate product formation through controlled elevated temperature processing
3Ease of manufacture
If diluted CO2 gas is used with limited contact time, then processing is simple, but CO2 sequestration and carbonate formation are insufficient
Solution Approach 1:
The patent introduces an intermediary approach by using a CO2-saturated solution as a mediator between the granular material and CO2 gas. This intermediary medium enhances carbonate formation efficiency and CO2 sequestration (forming at least 5% carbonates by weight) while maintaining process simplicity through a straightforward saturation and reaction procedure
4Productivity
If high pressure is applied to enhance CO2 penetration, then carbonate formation improves, but formation of unwanted calcium silicate hydrates increases
Solution Approach 1:
The patent applies dynamics by carefully controlling and optimizing pressure parameters to achieve the desired balance. By maintaining pressure at at least 0.5 MPa while controlling other parameters (temperature above 70°C, use of CO2-saturated solution), the process dynamically favors carbonate formation over calcium silicate hydrate formation, achieving high productivity with pure carbonate bonding
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces articles with significantly improved compressive strength, reduced porosity, and enhanced CO2 sequestration, achieving compressive strengths up to 65 MPa and low water absorption, while minimizing leaching of hazardous elements, thus making them suitable for construction materials.
Implementation Method 1
reacting the granular material in said compact with carbon dioxide in the presence of water to form at least 5% by weight of carbonates
Implementation Method 2
reacting the granular material in said compact with carbon dioxide in the presence of water
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2~3A
AI summary
A method of producing a mainly carbonate bonded article comprises a step of providing an alkaline granular material comprising one or more alkaline earth metal silicate phases. The method comprises a step of compacting the granular material to obtain a compact of the granular material. The porosity of the compact is smaller than or equal to 37% by volume. The intrinsic permeability of the compact is at least 1.10-12cm2. The method also comprises a reacting step arranged to form at least 5% by weight of carbonates (CO-2 3), by reacting the granular material with carbon dioxide in the presence of water, thus transforming the compact into the article. In the reacting step, the compact, being unsaturated with moisture at the beginning of the reacting step, is brought in an atmosphere comprising said carbon dioxide. The atmosphere is at a temperature of at least 70°C and at a pressure of at least 0.5 MPa. The pressure is also higher than the saturated vapour pressure of water at said temperature. As a result, at least a portion of said carbonates are formed by reaction of the one or more alkaline earth metal silicate phases. The invention is also related to an article obtained by the method.