High Solids PCC via Depolymerized Carboxylated Cellulose
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Solution Overview
Problem
Current processes for producing precipitated calcium carbonate (PCC) often require additional separation or concentration steps, which are energy-intensive and costly, and can damage the crystal structure of PCC, especially when using mechanical dewatering methods.
Innovation Solution
A process involving the use of depolymerized carboxylated cellulose with a molecular weight between 10,000 to 40,000 g/mol, mixed with calcium oxide in a weight ratio of 1:1 to 1:12 with water to create a milk of lime, which is then carbonated to produce a PCC suspension with high solids content without the need for mechanical or thermal concentration steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional PCC production processes are used with subsequent solids concentration steps, then PCC slurry can be obtained, but energy consumption increases and crystal structure is damaged
Solution Approach 1:
The patent applies preliminary action by adding depolymerized carboxylated cellulose to the milk of lime before carbonation occurs. This pre-treatment modifies the suspension properties in advance, enabling high solids content to be maintained throughout the carbonation process without requiring subsequent energy-intensive concentration steps. The polymer is incorporated at the beginning (slaking stage) rather than after carbonation, which is the key preliminary action that eliminates the need for later solids concentration.
Solution Approach 2:
The patent changes the molecular weight parameter of the carboxylated cellulose from typical high values to a specific range (10,000-40,000 g/mol). This parameter change in the polymer's molecular weight optimizes the suspension's viscosity and stability characteristics, allowing high solids content to be achieved while maintaining acceptable flow properties. The specific molecular weight range is critical for achieving the desired balance between solids content and suspension handleability.
2Quantity of substance
If mechanical dewatering processes are used to concentrate PCC slurry, then solids content increases, but crystal structure is destroyed
Solution Approach 1:
The patent applies preliminary action by adding depolymerized carboxylated cellulose to the milk of lime before carbonation occurs. This pre-treatment modifies the suspension properties in advance, enabling high solids content to be maintained throughout the carbonation process without requiring subsequent concentration steps. The polymer is incorporated at the beginning (slaking stage) rather than after carbonation, which is the key preliminary action that eliminates the need for later solids concentration.
Solution Approach 2:
The patent replaces mechanical dewatering systems with a chemical approach using depolymerized carboxylated cellulose. Instead of using centrifuges or filters that apply mechanical forces to concentrate the slurry, the invention uses the polymer to chemically modify the suspension properties, allowing high solids content to be achieved through controlled carbonation. This substitution of chemical for mechanical means preserves the delicate crystal structure while achieving concentration.
3Quantity of substance
If additional separation equipment is added to concentrate PCC slurry, then production cost increases, but process complexity increases
Solution Approach 1:
The patent applies preliminary action by adding depolymerized carboxylated cellulose to the milk of lime before carbonation occurs. This pre-treatment modifies the suspension properties in advance, enabling high solids content to be maintained throughout the carbonation process without requiring subsequent concentration steps. The polymer is incorporated at the beginning (slaking stage) rather than after carbonation, which is the key preliminary action that eliminates the need for later solids concentration.
Solution Approach 2:
The patent applies self-service by using the depolymerized carboxylated cellulose to automatically maintain suspension stability and prevent settling during the carbonation process. The polymer itself provides the functionality that would otherwise require external separation and re-suspension equipment. The suspension serves its own concentration needs through the polymer's stabilizing effect, eliminating the requirement for additional separation machinery.
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 allows for the direct production of PCC suspensions with high solids content and acceptable viscosity, avoiding the need for additional separation or concentration steps, thus reducing energy consumption and preserving the crystal structure of PCC.
Implementation Method 1
providing at least one depolymerized carboxylated cellulose... preparing a milk of lime by mixing water, the calcium oxide containing material, and the at least one depolymerized carboxylated cellulose
Implementation Method 2
providing a calcium oxide containing material... preparing a milk of lime by mixing water, the calcium oxide containing material
Implementation Method 3
carbonating the milk of lime obtained in step iii) to form an aqueous suspension of precipitated calcium carbonate
Implementation Method 4
carbonating the milk of lime obtained in step iii) to form an aqueous suspension of precipitated calcium carbonate
Implementation Method 5
carbonating the milk of lime obtained in step iii) to form an aqueous suspension of precipitated calcium carbonate
Data Source
Figure 1
AI summary
The present invention relates to a process for producing an aqueous suspension of precipitated calcium carbonate, wherein a depolymerized carboxylated cellulose is added during lime slaking. Furthermore, the present invention relates to an aqueous suspension of calcium carbonate and a precipitated calcium carbonate obtained by said process as well as the use thereof.