Silicate Froth Control in Atmospheric Leaching
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Solution Overview
Problem
Atmospheric metal sulfide leaching processes are hindered by froth formation, leading to reduced metal recovery due to incomplete leaching and shortened residence times, as elemental sulfur accumulates and forms a hydrophobic barrier, and prior methods using surfactants either fail to mitigate frothing effectively or contaminate downstream processes.
Innovation Solution
Introducing silicates from tailings or run-of-mine materials into the leach circuit to control frothing, utilizing attrition scrubbers and leach reactors, maintaining temperatures below the melting point of sulfur, and optimizing leach times to achieve high metal recovery without additional reagents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional atmospheric metal sulfide leaching is performed without additional reagents, then operational costs are reduced, but froth formation occurs leading to reduced metal recovery
Solution Approach 1:
The patent utilizes silicates that are already present in the leach circuit or can be obtained from tailings streams, eliminating the need to purchase and add separate defoaming reagents. The silicates naturally occurring in the system perform the froth control function, making the system self-sufficient and reducing operational costs while maintaining effective froth management.
Solution Approach 2:
The patent changes the chemical parameters of the leach circuit by introducing silicates, which alter the surface properties and interfacial tension to control froth formation. This parameter change allows the system to achieve effective froth control without adding complex reagent systems, maintaining cost-effectiveness while improving metal recovery.
2Object-affected harmful factors
If surfactants are added to control frothing, then froth formation is reduced, but downstream processes become contaminated
Solution Approach 1:
The patent uses silicates as an intermediary substance that mediates between the froth formation problem and the downstream process quality requirement. Silicates act as a natural defoaming agent that controls froth without introducing contaminants that would harm downstream processes, unlike conventional surfactants.
Solution Approach 2:
The patent employs silicates that are readily available and can be used in small amounts to control froth. These silicates are effectively disposable in the sense that they perform their function and are already present in the system or can be obtained from waste streams, avoiding the need for expensive, contamination-prone reagents.
3Reliability
If leach residence time is extended to ensure complete leaching, then metal recovery improves, but productivity decreases
Solution Approach 1:
The patent converts the harmful effect of froth formation into a beneficial outcome by using the same froth control mechanism to improve leach kinetics. By controlling froth with silicates, the system prevents metal loss and improves contact between lixiviant and sulfide particles, thereby enhancing recovery without requiring extended residence times.
Solution Approach 2:
The patent changes the physical and chemical parameters of the leach circuit through silicate addition, which improves mass transfer and reaction kinetics. This parameter change allows the system to achieve complete leaching faster, thereby improving both metal recovery and productivity simultaneously.
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
Significantly reduces frothing, enhances metal recovery to over 95% within shorter leach times, and avoids contamination of downstream processes by using readily available silicates, thereby improving overall leach kinetics and reducing operational costs.
Implementation Method 1
The appearance of a stable froth is generally the end result of interfacial activity, and involves the action of surface-active species such as surfactants (i.e., amphiphilic molecules) and additionally, or alternatively, fine particles whose surfaces are amphiphilic.
Implementation Method 2
Silicates from tailings or run-of-mine materials are introduced into the leach circuit to control frothing
Implementation Method 3
utilizing attrition scrubbers and leach reactors
Implementation Method 4
atmospheric leaching of metal sulphides
Implementation Method 5
portions of a metal sulfide concentrate which are to be leached, may be displaced from and therefore may leave contact with lixiviant
Data Source
AI summary
A method of controlling frothing during atmospheric or substantially atmospheric leaching of a metal sulfide is disclosed. In some embodiments, the method may comprise the steps of (a) producing a metal sulfide concentrate via flotation; (b) producing a tailings stream via flotation; and, (c) diverting a portion or all of said produced tailings stream to an atmospheric or substantially atmospheric sulfide leach circuit. A metal recovery flowsheet is also disclosed. In some embodiments, the metal recovery flowsheet may comprise a unit operation comprising: (a) a sulfide concentrator comprising a flotation circuit, the flotation circuit producing a metal sulfide concentrate stream, and a tailings stream; and, (b) an atmospheric or substantially atmospheric metal sulfide leach circuit. The sulfide concentrator may be operatively connected to the atmospheric or substantially atmospheric metal sulfide leach circuit via both of said metal sulfide concentrate stream, and said tailings stream.