Surface-Reacted Calcium Carbonate Using Weak Acids
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for preparing surface-reacted calcium carbonate materials rely on medium-strong to strong acids, such as phosphoric acid, which pose occupational safety risks and are subject to stringent regulations, limiting their practicality and economic viability.
Innovation Solution
A process involving a specific selection of water-soluble acids with a pKa greater than 2.5 and the use of gaseous CO2 to develop a surface-reacted calcium carbonate, avoiding the need for medium-strong to strong acids by forming water-soluble and insoluble calcium salts, thereby increasing the specific surface area without using hazardous materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If medium-strong to strong acids (pKa < 2.5) are used to prepare surface-reacted calcium carbonate, then the specific surface area is increased, but occupational safety risks and regulatory restrictions increase
Solution Approach 1:
The invention changes the key parameter of acid strength from strong/medium-strong (pKa < 2.5) to weak (pKa ≥ 2.5), specifically using acetic acid with pKa = 4.76. This parameter change maintains the ability to increase specific surface area through calcium salt deposition while eliminating the harmful effects associated with strong acids, including occupational safety risks and regulatory restrictions
Solution Approach 2:
The invention replaces expensive and restricted strong acids with cheap, readily available weak acids like acetic acid. Acetic acid is a common household substance that is not subject to regulatory restrictions, making the process more economically viable and practically implementable without special precautions
2Area of stationary object
If medium-strong to strong acids are used to prepare surface-reacted calcium carbonate, then the specific surface area is increased, but the process complexity and cost increase due to regulatory compliance
Solution Approach 1:
By changing the acid strength parameter to weak acids (pKa ≥ 2.5), the invention eliminates the need for complex regulatory compliance measures, special handling procedures, and safety infrastructure required for strong acids, thereby simplifying the overall process while maintaining surface area enhancement
3Area of stationary object
If medium-strong to strong acids are used to prepare surface-reacted calcium carbonate, then the specific surface area is increased, but the economic viability decreases
Solution Approach 1:
The invention uses cheap, readily available weak acids like acetic acid instead of expensive strong acids that require special handling and compliance infrastructure. Acetic acid is a common substance that does not require special storage, handling, or disposal procedures, significantly reducing manufacturing costs and improving economic viability
Solution Approach 2:
Changing from strong to weak acids eliminates regulatory compliance costs, special safety equipment requirements, and trained personnel needs, thereby improving the economic viability of the process while achieving the same technical outcome of increased specific surface area
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 process achieves a comparable specific surface area development to existing methods while eliminating the need for hazardous acids, enhancing safety and economic feasibility by using weaker acids like acetic acid and water-soluble salts to form insoluble calcium salts on the surface of calcium carbonate.
Implementation Method 1
contacting said GNCC with said acid and with said CO2; wherein said acid each having a pKa of greater than 2.5 and less than or equal to 7
Implementation Method 2
the reaction product or products of the said carbonate with gaseous CO2 formed in situ
Implementation Method 3
at least one water-soluble salt, which in the case of a hydrogen-containing salt has a pKa of greater than 7... and the salt anion of which is capable of forming water-insoluble calcium salts
Data Source
AI summary
The present application relates to a process for preparing a surface-reacted calcium carbonate in an aqueous environment. The process according to the present invention aims at avoiding the mandatory implementation of medium-strong to strong acids. Another aspect of the present invention is directed to an aqueous suspension of surface-reacted calcium carbonate which is obtainable by the inventive process.