Polyimide Composition for Scale Suppression in Heap Leach Stacks
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Solution Overview
Problem
Heap leaching processes face challenges such as non-uniform metal extraction due to permeability variations and high clay content, leading to under-leached areas and reduced metal recovery, along with scale formation issues in emitter lines and collection systems.
Innovation Solution
Applying an insoluble polyimide composition, such as polysuccinimide, to heap leach stacks that hydrolyzes into water-soluble products like polyaspartate, which suppresses scale formation and improves percolation, thereby enhancing metal extraction and reducing lime usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional leach solutions are used for heap leaching, then metal extraction can be achieved, but scale formation occurs in emitter lines and collection systems
Solution Approach 1:
The patent introduces polyimide polymers as intermediary substances that interfere with scale formation. These polymers act as mediators between the leach solution and scale-prone surfaces, preventing direct contact and adhesion. The polymers are applied to emitter lines and collection systems before scale formation occurs, creating a protective barrier that maintains metal extraction efficiency while preventing harmful scale deposits.
Solution Approach 2:
The patent modifies the chemical parameters of the leach solution by adding polyimide polymers. This changes the solution's properties to reduce its scale-forming tendency. The polymers alter the surface tension, viscosity, and chemical reactivity of the leach solution, making it less prone to scale formation while maintaining its metal extraction capability.
2Productivity
If high clay content ore is processed, then metal extraction can be achieved, but percolation is reduced and under-leached areas occur
Solution Approach 1:
The patent changes the physical and chemical parameters of the leach solution by adding polyimide polymers. These polymers modify the solution's viscosity, surface tension, and wetting properties, enabling it to penetrate clay-rich materials more effectively. The altered parameters allow the solution to overcome the barrier created by high clay content and achieve uniform percolation throughout the ore stack.
Solution Approach 2:
The patent applies polyimide polymers locally to specific areas of the ore stack where percolation problems are identified. This targeted application allows the solution to address local variations in permeability and clay content, ensuring uniform metal extraction throughout the entire stack rather than relying on uniform conditions that do not exist in high-clay ores.
3Productivity
If emitter lines are used for leach solution application, then efficient metal extraction can be achieved, but scale formation fouls the emitter lines
Solution Approach 1:
The patent applies polyimide polymers to emitter lines before scale formation occurs. This preliminary protective action prevents scale deposits from forming on the emitter line surfaces, eliminating the need for frequent cleaning and maintenance. The polymers are applied in advance to create a protective barrier that persists throughout the leaching operation, ensuring continuous efficient metal extraction without operational interruptions.
4Productivity
If lime is added to the heap, then metal extraction can be improved, but lime dissolution is incomplete and excess lime remains
Solution Approach 1:
The patent modifies the chemical parameters of the leach solution by adding polyimide polymers, which alters the solution's pH, viscosity, and reactivity. These parameter changes enhance the dissolution rate of lime additives in the heap, ensuring more complete reaction and reducing excess lime remaining in the system. The altered solution properties allow lime to dissolve and react more efficiently with the ore.
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 use of polyimide compositions increases metal recovery rates, reduces scale formation, and minimizes lime requirements, leading to more efficient and cost-effective heap leaching operations.
Implementation Method 1
an insoluble polyimide composition, such as polysuccinimide, to heap leach stacks that hydrolyzes into water-soluble products like polyaspartate
Data Source
AI summary
Disclosed is a method for treating heap leach stacks by applying an insoluble polyimide composition, such as polysuccinimide, to the surface of an ore stack and/or incorporating the insoluble polyimide composition throughout the ore stack. The insoluble polyimide composition is then exposed to an aqueous solution to initiate hydrolysis and produce one or more water soluble products, such as hydrolyzed polyimides, polycarboxylates, polycarboxylic acids and mixtures thereof that will permeate the ore stack at a concentration sufficient to suppress scale formation within the leach stack. The water soluble products may also act to suppress scale formation in piping and channels peripheral to the leach stack, thereby reducing maintenance expenses.