Titanium Dioxide Flocculation Assistant
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Solution Overview
Problem
Conventional sulfate processes for producing titanium dioxide face challenges in reducing the residual content of fine solid particles in the black solution, leading to quality losses and reduced throughput during further processing steps.
Innovation Solution
The process involves flocculating solids from a titanium-containing digestion solution using a combination of cationic polymers based on aminoalkyl (meth)acrylamide and poly-diallyldimethylammonium chloride (poly-DADMAC) as flocculant and coagulant, respectively, to enhance the separation of solids and reduce residual solids content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional flocculants are used to sediment solids from black solution, then coarse particles are removed, but fine solid particles remain in suspension with high residual content
Solution Approach 1:
The patent uses a composite flocculation system combining two different cationic polymers with distinct mechanisms: a high molecular weight polymer (2-10 million g/mol) for coarse particle aggregation and a low molecular weight polymer (500-500,000 g/mol) for fine particle flocculation. This composite approach enables simultaneous effective removal of both coarse and fine solid particles from the black solution, reducing residual solids content to below 1 g/L.
2Strength
If high molecular weight cationic polymers are used as flocculants, then coarse particles are effectively aggregated, but fine particles remain unflocculated
Solution Approach 1:
The patent segments the flocculation function into two distinct components based on molecular weight: a high molecular weight cationic polymer (2-10 million g/mol) that provides strong aggregation capability for coarse particles, and a low molecular weight cationic polymer (500-500,000 g/mol) that effectively flocculates fine particles. This segmentation allows each component to optimize its performance for its target particle size range.
3Productivity
If conventional sedimentation processes are used, then throughput is maintained, but quality losses occur due to residual fine particles
Solution Approach 1:
The patent changes the chemical parameters of the flocculation system by introducing a dual-polymer system with different molecular weights, charges, and mechanisms. This parameter change enables the system to achieve both high throughput (by maintaining efficient sedimentation) and high product purity (by reducing residual fine particles to below 1 g/L), eliminating the trade-off between productivity and precision.
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 significantly reduces the residual solids content in the black solution, improving the purity and quality of titanium dioxide production by effectively sedimenting both fine and coarse particles, thereby enhancing process efficiency and reducing quality losses.
Implementation Method 1
Many of the particles to be sedimented in the black solution have a charge or a dipole moment. If the repulsion between the individual particles is greater than gravity, these particles cannot sediment to the bottom of the container and remain in suspension. Only the addition of a flocculant can minimize the repulsion forces through an appropriate countercharge, so that the individual particles connect with each other
Implementation Method 2
the individual particles connect with each other as well as via agglomerates and sediment due to gravity
Data Source
Figure 1~3
Figure 4~5
AI summary
The present invention is directed to a process for obtaining titanium dioxide by the sulphate process, in which process a titanium-containing starting substance is digested with sulphuric acid in order to obtain a solids-containing digestion solution (black solution), from which titanium dioxide is obtained in further, subsequent process steps, wherein, before proceeding to the further process steps, the solids are sedimented and separated from the digestion solution in order to obtain a digestion solution (black solution) which is substantially free from solids, wherein, during the sedimentation, the solids are flocculated by a flocculation assistant and a coagulant, wherein the flocculation assistant contains a cationic polymer based on aminoalkyl (meth)acrylamide and/or aminoalkyl (meth)acrylate, and the coagulant contains a cationic polymer based on polydiallyldimethylammonium chloride (poly-DADMAC), and also to combination flocculation assistants suitable for this process.