Screw Press Filter Plate Clamping for Red Mud Dewatering
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Solution Overview
Problem
Current solid-liquid separation equipment is inadequate for efficiently dewatering red mud and similar slurries, particularly due to issues with blockages, low solid concentration, and inability to handle high pressures, leading to environmental and economic challenges in waste management.
Innovation Solution
A screw press with a continuous screw and stationary filtration plates clamped in intimate contact, maintaining constant pressure and preventing preferential passages, combined with a positive displacement pump for controlled slurry feeding, allowing for high-pressure filtration and efficient separation of fine particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spring-loading filter discs are used to maintain constant filtrate flow, then filtrate flow is maintained, but the apparatus becomes more complex and more liable to blockage
Solution Approach 1:
The patent removes the spring-loading mechanism and intermittent inlet system from the filtration apparatus. Instead, it uses a continuous screw press mechanism that applies constant pressure to the slurry, eliminating the need for moving filter discs and spring mechanisms while maintaining continuous filtration operation.
Solution Approach 2:
Rather than using spring-loaded discs that move apart to allow solids passage, the invention uses a screw press that continuously pushes solids through stationary filter plates. The filtration mechanism is inverted from a disc-based system to a screw-based system, achieving simpler operation without blockages.
2Ease of operation
If filter discs are forced apart during solids passage, then solids can pass through, but small particles remain stuck between discs creating preferential passages
Solution Approach 1:
The invention uses multiple filter plates with filtration surfaces that are arranged in series within the screw press. The slurry passes through multiple filtration stages as it is pushed by the screw, with solids being progressively separated. This segmented approach prevents particle accumulation that would create preferential passages.
Solution Approach 2:
The screw press applies continuous pressure to the slurry before it reaches the filter plates, pre-compressing the slurry and facilitating smoother passage of solids through the filtration surfaces. This preliminary compression action prevents particles from getting stuck between filtration surfaces.
3Quantity of substance
If gravity settlers are used for mud compacting, then liquid can be separated, but several hours are required to obtain solid concentration of only 45-50%
Solution Approach 1:
The screw press applies continuous mechanical pressure and compression to the slurry throughout the filtration process, pre-compressing the solids and forcing liquid extraction. This preliminary and continuous compression action achieves high solid concentration (70-80%) in a single pass, eliminating the need for prolonged gravity settling periods.
Solution Approach 2:
The invention replaces the passive gravity-based settling system with an active mechanical screw press system. The screw mechanism continuously applies mechanical pressure to compress solids and extract liquid, achieving rapid concentration up to 70-80% solid content, compared to only 45-50% with gravity settlers.
4Ease of repair
If intermittent inlet closing is used to clear solids, then solids can be discharged, but the filtration process is disrupted and complexity increases
Solution Approach 1:
The screw press mechanism operates continuously, with the screw constantly rotating to push slurry through the filter plates and discharge solids. There is no need to interrupt the filtration process to clear solids, as the continuous mechanical action naturally prevents solid accumulation and blockages, maintaining uninterrupted filtration operation.
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 screw press achieves a higher solid concentration of the compacted slurry, up to 70-80% for red mud, and effectively handles large quantities of slurry with fine particles, improving upon conventional methods by maintaining constant pressure and reducing blockages.
Implementation Method 1
a screw adapted to be rotatably mounted within the filter section for applying a pressure gradient to the slurry to force liquid through the filter plates
Implementation Method 2
a clamping assembly having first and second clamping plates respectively provided at opposed ends of the filter section with the filter plates disposed therebetween, the clamping assembly being operable for applying a predetermined clamping pressure substantially uniformly about an inner diameter of the plates
Data Source
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AI summary
A screw press (14) for separating liquid from a solid-liquid mixture, comprises a casing (18) having inlet and outlet sections (24, 26), and a filter section (28) therebetween. The filter section (28) includes an axially extending stack of coplanar filtration plates (36) defining a core passage for receiving a screw configured to convey the solid-liquid mixture from the inlet section (24) to the outlet section (26) while compressing and dewatering the solid-liquid mixture by forcing at least part of the liquid content of the mixture to be expelled out of the casing through inter-plate gaps (40) defined between each pair of adjacent filtration plates (36). The filtration plates (36) are fixed relative to one another and clamped in direct intimate face-to-face contact by a clamping assembly (38) operable for applying a predetermined axially clamping pressure substantially uniformly about the core passage. The inter-plate gaps (40) are controlled by the surface roughness (R) of the plates (36) and the clamping pressure.