Precipitated Calcium Carbonate from Deinking Residue Ash
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Solution Overview
Problem
The recycling of paper waste results in deinking residue that, when combusted, forms minerals unsuitable for use as paper pigments due to their hardness and abrasiveness, requiring further processing that can be costly and inefficient, especially since current methods often necessitate wet milling which incurs product losses and does not produce desirable whiteness or brightness.
Innovation Solution
A process to produce precipitated calcium carbonate particles from the ash of combusted deinking residue, where the ash composition is optimized to include at least 25 wt% CaO, allowing for direct use without wet milling, resulting in a composite mineral with controlled particle shape, size distribution, and reduced abrasivity, suitable for paper production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If deinking residue is combusted to recover minerals, then energy is produced and waste mass is reduced, but the resulting minerals have high hardness and abrasiveness making them unsuitable for paper pigments
Solution Approach 1:
The invention changes the chemical composition parameters of the ash by controlling the calcium content in the deinking residue before combustion. By ensuring the ash contains at least 25 wt% CaO through selective recycling of calcium-containing residues, the resulting precipitated calcium carbonate particles achieve desirable properties (low abrasivity, controlled morphology) without requiring wet milling, thus resolving the contradiction between energy recovery and mineral suitability
Solution Approach 2:
The invention creates a composite material system by combining calcium oxide from the ash with carbon dioxide to form precipitated calcium carbonate particles. This composite approach transforms the harmful high-abrasivity minerals into a beneficial composite pigment with controlled particle shape and size distribution, suitable for paper applications while maintaining energy recovery benefits
2Length of moving object
If wet milling is used to process combusted minerals, then particle size can be reduced, but product losses occur and desirable whiteness or brightness is not achieved
Solution Approach 1:
The invention performs preliminary action by controlling the calcium content in the deinking residue before combustion occurs. By pre-conditioning the material composition (ensuring ≥25 wt% CaO in ash), the subsequent carbonation process directly produces particles with desirable size and morphology without requiring additional wet milling steps, thus preventing product losses while achieving the desired particle characteristics
Solution Approach 2:
The invention replaces the mechanical wet milling system with a chemical precipitation process. Instead of using mechanical energy to grind particles (which causes product losses), the process uses chemical reaction (carbonation of calcium oxide) to directly form precipitated calcium carbonate particles with controlled size and morphology, eliminating the need for mechanical size reduction
3Length of moving object
If wet milling is used to process minerals, then particle size is reduced, but desirable whiteness and brightness are not achieved
Solution Approach 1:
The invention changes the chemical composition parameters by ensuring high calcium oxide content (≥25 wt%) in the ash before carbonation. This compositional control enables the precipitation process to produce particles with inherent desirable optical properties (whiteness and brightness) and controlled morphology, eliminating the need for wet milling that fails to achieve these optical characteristics
Solution Approach 2:
The invention utilizes phase transition through the carbonation reaction where calcium oxide transforms into precipitated calcium carbonate. This phase change process directly forms particles with desirable optical properties and morphology, providing a superior alternative to mechanical milling that cannot achieve the required whiteness and brightness
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 enables the production of composite precipitated calcium carbonate particles with well-defined morphology, controlled particle size, and low abrasivity, making them suitable for use as paper pigments without the need for wet milling, thereby reducing product losses and achieving desirable brightness and whiteness.
Implementation Method 1
the ash particles are carbonated to form composite precipitated calcium carbonate particles
Implementation Method 2
forming an aqueous slurry of ash particles... the ash particles are carbonated to form composite precipitated calcium carbonate particles
Data Source
AI summary
The current invention relates to methods of the recovery and re-use of minerals obtained from the combustion of the residues of a process to recycle paper.