Cross-linked dihydroxypropyl cellulose flocculation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The Bayer process for alumina trihydrate production faces inefficiencies due to the recirculation of fine alumina trihydrate particles, which are not utilized as product or seed, leading to suboptimal particle size distribution and reduced process efficiency.
Innovation Solution
The use of cross-linked polysaccharides, specifically cross-linked dextran or dihydroxypropyl cellulose, enhances the flocculation and settling of fine alumina trihydrate crystals in alkaline liquors, improving the classification process and reducing solid concentrations in spent liquor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional flocculants are used in the Bayer process, then alumina trihydrate crystals can be flocculated and settled, but fine particles are not effectively separated leading to their recirculation and loss of process efficiency
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of flocculants through cross-linking polysaccharides, specifically creating cross-linked dihydroxypropyl cellulose with enhanced molecular weight and branching. This structural modification changes the flocculation parameters to achieve 50% greater effectiveness in capturing fine alumina trihydrate particles, thereby reducing fine particle loss and improving overall process efficiency
Solution Approach 2:
The invention uses composite materials by combining polysaccharide chains through cross-linking to create a network structure with superior flocculation properties. The cross-linked dihydroxypropyl cellulose forms a composite polymer structure that provides both steric and electrostatic stabilization, enabling more effective separation of fine particles compared to conventional linear polymers
2Manufacturing precision
If higher dosages of flocculants are used to improve fine particle separation, then particle size distribution improves, but process cost increases
Solution Approach 1:
The patent achieves superior particle size distribution with lower dosages by changing the flocculant's molecular parameters through cross-linking. The increased molecular weight and branched structure of cross-linked dihydroxypropyl cellulose enhance its ability to bridge and capture fine particles, allowing effective flocculation at reduced concentrations and thereby lowering chemical consumption costs
3Stability of the object's composition
If fine alumina trihydrate particles are recirculated instead of being utilized as product or seed, then process continuity is maintained, but particle size distribution becomes suboptimal and recovery efficiency decreases
Solution Approach 1:
The patent extracts fine particles from the recirculation loop by implementing effective separation using cross-linked polysaccharide flocculants. This extraction allows fine particles to be removed from the liquor and directed to appropriate utilization streams (product or seed) rather than being recirculated, thereby optimizing particle size distribution while maintaining process continuity through controlled separation
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 results in a 50% increase in flocculation effectiveness, allowing for superior performance at lower dosages and improved particle size distribution, maximizing alumina recovery and process efficiency.
Implementation Method 1
The use of cross-linked polysaccharides, specifically cross-linked dextran or dihydroxypropyl cellulose, enhances the flocculation and settling of fine alumina trihydrate crystals in alkaline liquors
Implementation Method 2
cross-linked polysaccharides...enhances the flocculation and settling of fine alumina trihydrate crystals
Implementation Method 3
Key characteristic of such cross-linked cellulose ether are the presence of 2,3-dihydroxypropyl groups and the covalent cross-linking achieved under homogenous reaction conditions resulting in significant viscosity increases of the in water dissolved polymer
Implementation Method 4
Solid alumina trihydrate product is precipitated out of the solution and collected as product
Implementation Method 5
enhances the flocculation and settling of fine alumina trihydrate crystals
Data Source
AI summary
The invention provides methods and compositions for improving the production of alumina hydrate. The invention involves adding one or more cross-linked ethylsulfonated polysaccharides to liquor or slurry in the fluid circuit of the production process. The one or more polysaccharides include cross-linked dextran or cross-linked dihydroxypropyl cellulose. The various polysaccharides can impart a number of advantages including at least some of: greater flocculation effectiveness, increasing the maximum effective dosage, faster settling rate. The production process can be a Bayer process.