Precipitated Calcium Carbonate Crystallization Using Waste CO2
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Solution Overview
Problem
Existing methods for producing precipitated calcium carbonate are energy intensive and generate greenhouse gases, necessitating a more sustainable and efficient process.
Innovation Solution
A method involving the absorption of carbon dioxide with a sodium hydroxide solution to form carbonate anions, followed by reaction with a calcium-containing salt to produce calcium carbonate, which is then matured to achieve a desired crystal structure, utilizing waste streams from waste-to-energy plants to reduce environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If limestone is calcinated at high temperature to form calcium oxide, then calcium carbonate can be produced, but energy consumption increases and greenhouse gas emissions occur
Solution Approach 1:
The invention changes the temperature parameter from high-temperature calcination (1000°C) to low-temperature precipitation (20-100°C). Instead of thermal decomposition, the process uses chemical precipitation by adding calcium chloride to sodium carbonate solution, fundamentally altering the temperature condition to reduce energy consumption while maintaining product quality
Solution Approach 2:
The invention replaces the thermal-mechanical calcination process with a chemical precipitation process. Instead of using high temperature and mechanical grinding, the process utilizes chemical reactions between calcium chloride and sodium carbonate to directly form calcium carbonate precipitate, eliminating the need for energy-intensive heating and grinding equipment
2Manufacturing precision
If limestone is calcinated at high temperature, then calcium oxide is formed, but carbon dioxide emissions increase
Solution Approach 1:
The invention converts the harmful carbon dioxide emissions from calcination into a beneficial raw material. By using sodium carbonate (which can be produced from CO2) as a reactant in the precipitation process, the method transforms the waste gas into a useful chemical intermediate, effectively utilizing what would otherwise be a harmful emission
Solution Approach 2:
The invention extracts and eliminates the high-temperature calcination step that generates CO2 emissions. By directly using sodium carbonate and calcium chloride solutions to precipitate calcium carbonate, the process removes the carbon-intensive calcination stage entirely, preventing CO2 generation at the source while maintaining product output
3Manufacturing precision
If multiple process steps are used for calcium carbonate production, then product quality can be achieved, but process complexity increases
Solution Approach 1:
The invention merges multiple traditional process steps (calcination, slaking, carbonation, grinding) into a single precipitation step. By combining the formation of calcium carbonate in one chemical reaction and achieving both product formation and particle size control simultaneously, the process reduces the number of unit operations and equipment required while maintaining product quality specifications
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 effectively produces precipitated calcium carbonate with a desired crystal structure while utilizing waste carbon dioxide and reducing energy consumption and greenhouse gas emissions.
Implementation Method 1
forming a first mixture comprising carbonate anions by feeding sodium hydroxide containing solution and carbon dioxide containing gas into an absorption reactor to absorb carbon dioxide with the sodium hydroxide containing solution
Implementation Method 2
obtaining a calcium carbonate containing suspension by feeding said first mixture comprising carbonate anions and a calcium containing salt solution into a precipitation reactor
Implementation Method 3
maturing the calcium carbonate containing suspension by mixing for obtaining a matured product comprising precipitated calcium carbonate having a desired crystal structure
Data Source
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AI summary
A method of and apparatus for producing precipitated calcium carbonate, comprising steps of: forming a first mixture comprising carbonate anions by feeding sodium hydroxide containing solution and carbon dioxide containing gas into an absorption reactor to absorb carbon dioxide with the sodium hydroxide containing solution; obtaining a calcium carbonate containing suspension by feeding said first mixture comprising carbonate anions and a calcium containing salt solution into a precipitation reactor; maturing the calcium carbonate containing suspension by mixing for obtaining a matured product comprising precipitated calcium carbonate having a desired crystal structure and a supernatant; and separating said precipitated calcium carbonate having the desired crystal structure and the supernatant from the matured product.