Auxiliary Agitator for Large Flotation Tank Secondary Flow
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Solution Overview
Problem
Large flotation devices face inefficiencies in maintaining flotation kinetic rates as they increase in size, with the primary rotor's secondary flow becoming insufficient to draw floatable particles back into the mixing zone, leading to reduced cell efficiency, particularly in devices with capacities greater than 150 m3 to 200 m3.
Innovation Solution
An auxiliary agitator is introduced, featuring adjustable blades connected to the drive shaft, which supplements the axial flow induced by the primary rotor, increasing the secondary flow turnover rate and ensuring floatable particles are refloated, and includes a resilient protective layer and adjustable positioning for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the size of flotation devices is increased to improve economic efficiency, then the processing capacity increases, but the secondary flow becomes insufficient to draw floatable particles back into the mixing zone, reducing cell efficiency
Solution Approach 1:
The single primary rotor is segmented into two independent agitation systems: the primary rotor for main agitation and the auxiliary agitator for supplemental secondary flow. This segmentation allows each component to be optimized for its specific function, with the auxiliary agitator specifically designed to restore the secondary flow capability that is lost in large-scale single-rotor systems.
Solution Approach 2:
The auxiliary agitator acts as an intermediary element between the primary rotor and the tank wall/bottom surfaces. It mediates the flow patterns by inducing secondary currents that draw particles from the tank periphery back into the mixing zone, compensating for the insufficient secondary flow of the primary rotor in large-scale applications.
2Power
If the size of flotation devices is increased, then the agitation input energy must increase proportionally, but the secondary flow turnover rate decreases, leading to particle loss
Solution Approach 1:
The agitation function is segmented into primary agitation (primary rotor) and secondary flow generation (auxiliary agitator). This allows the system to maintain appropriate secondary flow turnover rates even in large-scale applications, as the auxiliary agitator is specifically positioned and designed to generate localized secondary currents near the tank periphery.
Solution Approach 2:
The auxiliary agitator provides localized secondary flow enhancement at the tank periphery and bottom regions where particles tend to accumulate. Rather than attempting to increase overall agitation energy uniformly throughout the tank, the auxiliary agitator focuses its action on the specific zones where secondary flow is needed to draw particles back into the mixing zone.
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 auxiliary agitator enhances the secondary flow in large flotation devices, increasing the probability of refloating particles and improving overall recovery efficiency, comparable to a group of smaller cells of equivalent total volume, while also facilitating reagent dispersion and preventing vortexing at the tank surface.
Implementation Method 1
an auxiliary agitation blade adapted, in use, to supplement an axial flow induced in the tank by the primary rotor
Implementation Method 2
an auxiliary agitator including: an auxiliary agitation blade adapted, in use, to supplement an axial flow induced in the tank by the primary rotor
Implementation Method 3
the agitator includes a resilient protective layer coating its exterior surfaces
Implementation Method 4
An aeration system is also provided to direct air under pressure into the agitator through a central conduit formed within the drive shaft
Implementation Method 5
Suitable reagents are also added, which coat the surfaces of the mineral particles within the slurry to make the particles hydrophobic so as to preferentially promote bubble to particle attachment
Implementation Method 6
As bubbles dispersed by the rotor rise toward the surface of the tank, they carry with them floatable valuable mineral particles, which form a mineral enriched surface froth
Data Source
AI summary
The invention provides an agitator (1) is disposed to agitate slurry within a flotation tank (2). The agitator includes a rotor (6) mounted on one end of a centrally disposed drive shaft (7) extending axially downwardly into the tank and driven by a motor (8) and associated gearbox (not shown). The other end of the drive shaft includes a mounting flange (9) adapted for connection to the motor. A stator (10) is also provided around the rotor. A froth deflection cone (11) extends around the drive shaft adjacent the top of the tank. The deflection cone is oriented such that its smallest diameter is located at its lower-most end nearest the rotor (6). An auxiliary agitator (12) is connected to the drive shaft at a position substantially midway between the underside of the deflection cone (11) and the top of the rotor (6), as shown in FIG. 1 and FIG. 2. The auxiliary agitator (12) includes agitation blades (13) extending radially outwardly from diametrically opposite sides of the shaft (7). Each blade (13) intersects the shaft at an angle of incidence of around 45 degrees to the shaft axis (14).