Precipitated Calcium Carbonate Particle Size Control via Energy Input
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Solution Overview
Problem
Current methods for producing precipitated calcium carbonate (PCC) struggle to achieve a defined particle size and distribution, which is crucial for various industrial applications such as thermal paper, copy paper, and plastics, due to the complex interaction of multiple parameters in batch processes, leading to inconsistent product quality.
Innovation Solution
The method involves recording and controlling specific molar energy input during the PCC production process by adjusting CO2 concentration, temperature, reactor fill level, and gassing stirrer speed to achieve a desired grain size distribution, with a D4.3/D90 ratio of 59 or higher, allowing for targeted particle size specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If batch mode production with conventional aeration systems is used, then existing PCC plant infrastructure can be utilized, but the particle size distribution becomes broad and undefined
Solution Approach 1:
The patent implements dynamic control of aeration parameters during the batch process. The aeration rate, CO2 concentration, and stirrer speed are continuously adjusted based on real-time monitoring of particle formation stages, transitioning from high aeration during nucleation to lower aeration during growth phases. This dynamic adjustment enables precise particle size control using conventional batch reactor infrastructure.
Solution Approach 2:
The patent systematically varies multiple process parameters including aeration rate, CO2 concentration, temperature, and stirrer speed throughout the reaction sequence. By changing these parameters at specific time points corresponding to different crystallization stages (nucleation, growth, maturation), the process achieves narrow particle size distribution without requiring new equipment.
2Productivity
If CO2 concentration and aeration rate are increased to accelerate reaction, then productivity improves, but particle size control and distribution narrowness deteriorate
Solution Approach 1:
The patent employs periodic variation of aeration rate and CO2 concentration throughout the batch process. High aeration rates and CO2 concentrations are applied periodically during specific phases (nucleation and early growth) to maintain high productivity, then reduced during later phases to refine particle size distribution. This periodic control strategy reconciles the conflict between reaction rate and particle uniformity.
3Manufacturing precision
If multiple process parameters are adjusted to control particle size, then particle size specification is achieved, but process complexity and difficulty of control increase
Solution Approach 1:
The patent employs pre-calculated aeration profiles and parameter sequences that are determined before the batch process begins. Based on the desired particle size specification, the optimal sequence of aeration rates, CO2 concentrations, and stirrer speeds is predetermined and automatically executed. This preliminary planning simplifies real-time control while achieving precise particle size control.
Solution Approach 2:
The patent implements monitoring of key process parameters (pH, conductivity, temperature, aeration rate) throughout the batch process. This feedback information is used to verify that the predetermined parameter sequence is being followed and to make minor adjustments if deviations occur, ensuring consistent particle size results across multiple batches.
4Reliability
If narrow particle size distribution is achieved through systematic control, then application-specific performance improves, but loss of flexibility in adapting to different applications decreases
Solution Approach 1:
The patent uses dynamic, programmable control of aeration and process parameters that can be easily reconfigured for different particle size specifications. By implementing control sequences as programmable recipes rather than fixed hardware configurations, the system maintains high adaptability to different applications (thermal paper, copy paper, plastics) while achieving narrow particle size distributions for each specific application.
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 approach enables the production of PCC with a narrow and defined particle size distribution, improving the quality of PCC for specific applications by ensuring consistent grain sizes within desired ranges, enhancing properties like opacity and manufacturing process stability.
Implementation Method 1
PCC is formed in an aqueous suspension of Ca(OH)2 (the so-called lime milk) by introducing CO2
Implementation Method 2
a phase of preferential nucleation at the very beginning, followed by a phase of generally favored nucleation growth
Data Source
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AI summary
The invention relates to a process for producing precipitated calcium carbonate (PCC) with a defined particle size and particle size distribution. Furthermore, the invention relates to PCC that can be produced according to the process and has a defined particle size and particle size distribution. The invention is based, among other things, on the finding that the specific molar energy input is the decisive controlling parameter for the particle size.