Cross-linked Polysaccharides for Bayer Process Filtration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The Bayer process for producing alumina trihydrate from bauxite ore faces inefficiencies in filtration steps, particularly in the separation of solids from liquids, leading to suboptimal filtration rates and residual liquor content in the filtered solid cake.
Innovation Solution
The introduction of cross-linked polysaccharides, such as cross-linked dextran or dihydroxypropyl cellulose, into the slurry before filtration enhances the filtration process by improving the separation efficiency and reducing the moisture content in the filtered solid cake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional filtration methods are used in the Bayer process, then the filtration process is simpler and requires fewer additives, but the filtration rate is lower and residual liquor content in the solid cake is higher
Solution Approach 1:
A polysaccharide composition is introduced as an intermediary substance between the slurry and the filter medium. The polysaccharide modifies the interfacial properties between liquid and solid phases, acting as a mediator that enhances liquid passage through the filter cake while maintaining solid retention, thereby increasing filtration rate without complicating the filtration equipment
Solution Approach 2:
The polysaccharide composition changes the physical-chemical parameters of the slurry system, including surface tension, viscosity, and wettability characteristics. These parameter changes improve the flow properties of the liquid phase through the filter cake and modify the interaction between particles and filter medium, resulting in enhanced filtration performance
2Quantity of substance
If conventional filtration methods are used in the Bayer process, then fewer chemicals are required, but the residual liquor content in the filtered solid cake is higher
Solution Approach 1:
The polysaccharide composition serves as a beneficial intermediary that selectively modifies the liquid-solid separation interface. It reduces the capillary retention of liquor in the filter cake pores through surface modification effects, enabling more complete liquid removal while the polymer itself remains in minimal quantities and can be managed in the process stream
3Manufacturing precision
If cross-linked polysaccharides are added to enhance filtration, then filtration rate and separation efficiency improve, but the process requires additional chemical additives and process steps
Solution Approach 1:
The polysaccharide composition is added to the slurry in advance of the filtration operation, allowing sufficient time for the polymer to adsorb onto particle surfaces and modify interfacial properties before the slurry enters the filter. This preliminary action ensures optimal separation efficiency is achieved during filtration without requiring additional process steps during the filtration operation itself
Data Source
AI summary
The invention provides methods and compositions for improving the production of alumina trihydrate. The invention involves adding one or more cross-linked polysaccharides to a filter used to separate solids from liquid in the Bayer process. The one or more polysaccharides can be a cross-linked polysaccharide (such as cross-linked dextran or cross-linked dihydroxypropyl cellulose). The cross-linked polysaccharides can impart a number of advantages including greater flow rate and lower residual moisture in the resulting cake.