Steel Slag Carbonation Method for CO2 Fixation
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Solution Overview
Problem
Existing methods for fixing carbon dioxide using natural mineral or steel slag are inefficient, requiring long reaction times, high energy consumption, and are not economically practical due to low reaction efficiency and difficulties in separating carbonates, especially when pH adjustment leads to the formation of suspending milky lime.
Innovation Solution
A method involving acid treatment of natural mineral or steel slag to extract metal ion components, followed by carbonation with carbon dioxide at normal temperature and pressure, omitting the need for initial pH adjustment, allowing for continuous processing and efficient carbonate separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carbon dioxide is fixed by reacting with carbonate minerals or steel slag, then carbon dioxide can be fixed, but the reaction time is too long and reaction efficiency is very low
Solution Approach 1:
The patent changes the physical state of carbon dioxide from gas to liquid by pressurizing it to 0.5-5 MPa, and adjusts the temperature to 25-100°C. This parameter change enables the liquid-phase carbonation reaction to proceed rapidly at much shorter times (minutes rather than days), dramatically improving reaction efficiency while reducing reaction time.
Solution Approach 2:
The patent introduces a liquid CO2 medium as an intermediary that facilitates the carbonation reaction. The liquid CO2 serves as both the reactant and the reaction medium, enabling efficient mass and heat transfer between the CO2 and the alkaline components in the mineral or steel slag, thereby accelerating the reaction rate.
2Productivity
If hydrothermal reaction is used to solidify carbon dioxide, then carbon dioxide can be fixed, but energy consumption is very high
Solution Approach 1:
The patent modifies the reaction conditions by using liquid CO2 at moderate pressure (0.5-5 MPa) and temperature (25-100°C) instead of high-temperature hydrothermal conditions. This parameter change reduces energy consumption significantly while maintaining effective carbon dioxide fixation capability.
Solution Approach 2:
The patent replaces the energy-intensive hydrothermal reaction system with a liquid-phase carbonation system. By using liquid CO2 under moderate pressure and temperature, the process eliminates the need for high-temperature heating and complex hydrothermal treatment, thereby reducing energy consumption while achieving the same carbonation objective.
3Productivity
If pH is adjusted to fix carbon dioxide through carbonation, then carbonates can be formed, but milky lime forms and suspends in the solution making separation difficult
Solution Approach 1:
The patent controls the pH of the carbonation reaction to remain between 8-11, avoiding excessive pH increase that would cause milky lime formation. By optimizing the pH range and using liquid CO2 carbonation, the process forms carbonates efficiently while preventing suspension formation, making separation easier and enabling continuous operation.
Solution Approach 2:
The patent uses liquid CO2 as an intermediary that carbonates the alkaline components without requiring sharp pH adjustment. The liquid CO2 gradually reacts with the mineral or steel slag components, forming carbonates in-solution without creating the sudden pH change that leads to milky lime precipitation and suspension.
4Productivity
If mineral carbonation is performed with excessive pulverization to achieve fine particle size, then reaction efficiency improves, but energy consumption increases excessively
Solution Approach 1:
The patent changes the state of CO2 to liquid phase, which enables effective carbonation reactions to proceed with coarser particle sizes. The liquid CO2 provides sufficient contact and reaction efficiency even when the mineral or steel slag is not excessively pulverized, thereby reducing the energy consumption associated with grinding and pulverization while maintaining adequate reaction productivity.
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
This method enables rapid and efficient carbon dioxide fixation, reducing energy consumption and preventing the formation of suspending solids, enabling large-scale treatment and utilization of previously discarded steel slag to mitigate greenhouse gas emissions.
Implementation Method 1
treating natural mineral or steel slag with an acid to extract metal ion components
Implementation Method 2
injecting carbon dioxide to an extraction solution containing the metal ion components obtained in step (a) to carbonate the same
Implementation Method 3
transferring a solution in which carbonates resulting from step (b) are dissolved to a dissolved carbonate storage tank
Implementation Method 4
transferring the stored dissolved carbonates to a carbonate separation/purification tank and adjusting pH to about 7 or above to separate the carbonates
Data Source
AI summary
A method and system of fixing carbon dioxide is provided. After metal ion components are extracted from, e.g., natural mineral or steel slag through acid treatment, carbon dioxide is injected to fix carbon dioxide by carbonating the same. Since the procedure of pH adjustment is unnecessary, the reaction is carried out effectively and a continuous process is enabled. Accordingly, the disclosed method of fixing carbon dioxide enables effective removal of carbon dioxide produced from the steelmaking industry, thereby significantly reducing greenhouse gas emission and allowing recycling of the discarded steel slag.