Feedwell Mixing Space for Thickener Flocculation
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Solution Overview
Problem
In thickening processes, the short retention time of solid particles within the feedwell leads to inefficient mixing with dilution liquid and flocculant, resulting in partial flocculation due to direct flow of feed material to the bottom outlet, especially for coarse particles.
Innovation Solution
A thickening apparatus with a separate mixing space inside the feedwell, featuring a horizontal element and plate elements that restrict flow, dissipates kinetic energy and enhances mixing by creating a reduced volume, allowing the feed material to flow through holes or between vane elements, thereby prolonging retention time and improving mixing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feed material flows directly through the feedwell to the bottom outlet, then the flow path is short and simple, but the retention time is insufficient and mixing efficiency deteriorates
Solution Approach 1:
The feedwell is divided into multiple functional zones: an upper mixing zone with horizontal plate elements that create turbulence and mixing, and a lower flow zone that directs material to the outlet. This segmentation forces the feed material to traverse a longer, more complex path through different zones, increasing retention time while maintaining flow rate. The horizontal plate elements create multiple flow paths and eddies that enhance mixing without reducing overall productivity.
2Ease of operation
If feed material flows directly to the bottom outlet, then the flow path is direct, but mixing with dilution liquid and flocculant is insufficient
Solution Approach 1:
The horizontal plate elements in the upper feedwell create mechanical turbulence and vortex flow patterns as feed material passes over them. This mechanical disturbance enhances mixing between feed material, dilution liquid, and flocculant by creating eddies and increasing contact between different streams. The turbulence generated by the plate elements ensures thorough mixing without requiring additional mechanical mixers, maintaining operational simplicity while improving composition homogeneity.
3Device complexity
If feed material flows directly to the bottom outlet, then the structure is simple, but flocculation is only partial especially for coarse particles
Solution Approach 1:
The horizontal plate elements act as intermediary structures that mediate between the simple feedwell structure and the requirement for effective flocculation. These plates create a controlled turbulence zone that enhances mixing and flocculation without requiring complex mechanical mixers or multiple chambers. The plate elements serve as passive flow control devices that improve flocculation efficiency for both fine and coarse particles while adding minimal structural complexity to the feedwell design.
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 apparatus effectively mixes the feed material with dilution and flocculant streams, reducing short-circuiting and enhancing flocculation, leading to improved settling efficiency in the thickening process.
Implementation Method 1
the mixing of the fed material is enhanced by the dissipation of the available kinetic energy of the fed material in the reduced volume
Implementation Method 2
In the tank the suspended particles form a thickened mud on the bottom of the tank. The thickened material settles to the bottom of the thickener tank
Data Source
AI summary
A thickening apparatus (1) and method adapted to liquids carrying suspended particles, such as slurry containing minerals, when there is a tank (2), where settling of solids takes place, a feedwell (4), which includes a chamber having means for receiving fed material (11), such as slurry and at least one outlet (5) in fluid communication with the tank and means for distributing the material in the tank, means for delivering the fed material (11), at least slurry, into the feedwell, when inside the feedwell there is arranged a separate mixing space (12) for the fed material (11), when there is arranged at least one horizontal element (7, 15, 22, 23) reaching at least partly the cross-section of the feedwell, from which mixing space the fed material (11) is allowed to flow into other section (14) of the feedwell.