Micro-Nanobubble Flotation for Silver Recovery from Acidic Overflow
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Solution Overview
Problem
Recovery of fine colloidal precious metals from aqueous solutions with low pH and high viscosity is challenging due to small particle sizes, leading to inefficiencies and losses in traditional separation methods like filtration and flotation, especially in strong acid leach stage thickener overflow.
Innovation Solution
Employing micro- and nanobubble flotation technologies, such as induced gas flotation (IGF), dissolved gas flotation (DGF), and electroflotation, which generate bubbles smaller than 1 µm to effectively separate and recover precious metals like silver from sedimentation unit overflows, including thickener, clarifier, or pond overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional filtration methods are used to recover fine colloidal precious metals, then separation is attempted, but the particle size is too small for effective filtration and filters become clogged or disintegrate
Solution Approach 1:
The patent replaces mechanical filtration systems with flotation technology. Instead of using filters that mechanically block particles (which clog or disintegrate with fine colloidal particles), the invention uses flotation where air bubbles attach to precious metal particles and carry them to the surface for recovery. This substitution of mechanical separation with physicochemical flotation resolves the contradiction between separation capability and filter durability.
Solution Approach 2:
The patent changes the separation mechanism from size-based mechanical filtration to surface property-based flotation. By adjusting parameters such as pH, adding collectors and frothers, and controlling bubble size, the flotation process can effectively separate fine colloidal particles (P80 < 40 μm, preferably P80 < 10 μm) that are too small for conventional filtration, thereby resolving the contradiction between handling fine particles and maintaining filter reliability.
2Productivity
If conventional flotation with large bubbles (600-2500 μm) is used, then flotation process is simple, but fine particles (P80 < 40 μm) escape removal
Solution Approach 1:
The patent applies segmentation by dividing the bubble population into smaller size ranges (microbubbles 1-100 μm and nanobubbles < 1 μm) compared to conventional large bubbles (600-2500 μm). This segmentation of bubble size allows for more effective attachment to and removal of fine colloidal precious metal particles (P80 < 40 μm), thereby improving recovery efficiency and reducing precious metal loss in the overflow.
Solution Approach 2:
The patent changes the bubble size parameter from conventional 600-2500 μm to microbubble (1-100 μm) and nanobubble (< 1 μm) ranges. This parameter change in bubble size is critical for effectively capturing fine particles that escape conventional flotation, as smaller bubbles have better attachment characteristics with fine colloidal particles, thus improving productivity and reducing substance loss.
3Manufacturing precision
If filtration is attempted on fine colloidal material in strong acid solution, then separation is tried, but filters cannot handle the harsh environment without disintegrating
Solution Approach 1:
The patent replaces the mechanical filtration system with a flotation system that is more tolerant of harsh acidic environments. The flotation process uses chemical reagents (collectors, frothers) and air bubbles rather than mechanical filter media, eliminating the problem of filter disintegration in strong acid solutions while maintaining separation capability for fine colloidal precious metals.
Data Source
Figure 1
AI summary
The present invention relates to a method for recovering at least one precious metal from an aqueous solution containing said metal and particularly to recovery of silver and optionally one or more other precious metals from overflow of a sedimentation unit such as a thickener, a clarifier or a pond.