Silane-Based Polymers for Bayer Process Scale Inhibition
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Solution Overview
Problem
The Bayer process in alumina manufacturing faces challenges with the formation of aluminosilicate scale, which leads to equipment obstructions, reduced heat exchanger efficiency, and requires hazardous acid de-scaling, while previous polymer solutions suffer from viscosity issues and low production throughput.
Innovation Solution
The use of silane-based polymers with dialkyloxy or monoalkyloxy configurations, rather than trialkyloxy, to inhibit scale formation by altering the morphology of aluminosilicate scale and selectively targeting DSP, reducing its accumulation on equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trialkoxysilane grafted polymers are used to inhibit scale formation, then scale inhibition effectiveness is improved, but viscosity increases and production throughput decreases
Solution Approach 1:
The patent changes the chemical structure parameter of the silane group from trialkoxysilane to dialkyloxy or monoalkyloxy configuration. This parameter change reduces the polymer's viscosity while maintaining its ability to inhibit scale formation, thereby improving production throughput without sacrificing scale inhibition effectiveness
Solution Approach 2:
The patent modifies the local chemical structure by reducing the number of alkyloxy groups on the silicon atom from three to two or one. This local quality change allows the polymer to maintain its scale-inhibiting function while reducing unwanted side effects like excessive viscosity and slow dissolution
2Reliability
If trialkoxysilane grafted polymers are used to inhibit scale formation, then scale inhibition effectiveness is improved, but reaction time increases
Solution Approach 1:
The patent changes the chemical structure parameter of the silane group from trialkoxysilane to dialkyloxy or monoalkyloxy configuration. This parameter change accelerates the reaction and dissolution process, reducing the time required for the polymer to become effective while maintaining scale inhibition performance
3Quantity of substance
If desilication step is used to reduce silica concentration, then overall silica concentration is reduced, but scale precipitation can still occur due to changing process conditions
Solution Approach 1:
The patent introduces silane-based polymers as an intermediary substance that modifies the surface properties of aluminosilicate scale. This mediator prevents scale from adhering to equipment surfaces even when silica concentration is reduced through desilication, providing reliable scale prevention that is not dependent on maintaining specific silica concentration levels
Solution Approach 2:
The patent applies the polymer treatment in advance to modify the surface properties of potential scale deposits. This preliminary action creates a protective effect that prevents scale adhesion before it becomes a problematic accumulation, even when process conditions change and silica precipitation occurs
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
The silane-based polymers effectively extend the induction time of scale formation, alter its morphology to prevent accumulation, and reduce fouling, achieving significant scale reduction without interfering with other mineral particles, thus improving process efficiency and reducing downtime.
Implementation Method 1
The silane-based polymers effectively extend the induction time of scale formation, alter its morphology to prevent accumulation
Data Source
AI summary
Diallcoxysilane and monoalkoxysilane functionalized polymers were applied as scale control agents in Bayer process. The polymer inhibitors reduced the quantity of aluminum silicate scale formed in spent liquor while significantly changed the morphology of the scale. Also a method is provided for reducing aluminum silicate scale of Bayer process by adding the dialkoxysilane and monoalkoxysilane functionalized polymer into the Bayer liquor stream.