Subsurface Raffinate Injection for Low-Permeability Ore Heaps
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Solution Overview
Problem
Conventional heap leaching processes face inefficiencies due to low permeability in ore heaps caused by high clay content, precipitation of compounds like jarosite, and non-uniform percolation, leading to incomplete metal recovery and waste of leaching solutions.
Innovation Solution
A subsurface leaching system with pressure, flow, and volume control, combined with residual metal mapping and additive-enhanced solutions, targets specific locations and depths within leach heaps using citric acid and hydrogen peroxide to optimize recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional surface heap leaching is used, then the process is simple and cost-effective, but low permeability materials prevent leaching solution percolation and metal recovery
Solution Approach 1:
The patent transitions from surface-level leaching to subsurface injection by drilling injection holes into the heap. This dimensional change allows leaching solution to be delivered directly to the pad layer beneath the ore, bypassing the permeability barriers in the upper ore layers and enabling metal recovery from previously inaccessible zones.
Solution Approach 2:
The patent introduces a pad layer as an intermediary component between the ore and collection system. This pad layer acts as a mediator that receives leaching solution from injection holes and facilitates uniform distribution to collection pipes, solving the percolation problem caused by low permeability materials in the ore itself.
2Device complexity
If leaching solution is distributed on surface, then the system is simple, but non-uniform percolation occurs and some areas remain unleached
Solution Approach 1:
The patent segments the leaching solution distribution system into multiple injection holes distributed across the heap surface. Each injection hole delivers solution to a specific localized area, ensuring uniform coverage. This segmentation replaces the single-point surface distribution with multiple controlled injection points, achieving uniform percolation throughout the heap.
Solution Approach 2:
The patent replaces the gravity-driven surface percolation mechanism with a pressure-controlled subsurface injection system. By using pumped leaching solution delivered through injection holes, the system gains mechanical control over solution distribution, ensuring uniform pressure and flow rates that prevent channeling and achieve consistent leaching across all heap areas.
3Object-generated harmful factors
If jarosite precipitation occurs, then iron is removed from solution, but permeability decreases and metal recovery is hindered
Solution Approach 1:
The patent extracts the harmful jarosite precipitation process from the ore leaching zone by delivering leaching solution directly to the pad layer beneath. This spatial separation prevents jarosite formation in the ore where it would block permeability, while still enabling effective metal recovery from the heap through the controlled subsurface injection system.
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
Maximizes metal recovery by addressing permeability issues and jarosite precipitation, ensuring uniform leaching and efficient use of leaching solutions, thereby improving economic outcomes.
Implementation Method 1
A subsurface leaching system with pressure, flow, and volume control
Implementation Method 2
The pipes or other conduits may have nozzles or other orifices that are designed to emit leaching solution at a particular flow condition
Implementation Method 3
additive-enhanced solutions, targets specific locations and depths within leach heaps using citric acid and hydrogen peroxide
Implementation Method 4
additive-enhanced solutions, targets specific locations and depths within leach heaps using citric acid and hydrogen peroxide
Implementation Method 5
precipitation of compounds like jarosite
Data Source
AI summary
The present disclosure provides a method comprising determining an ore map for a heap to identify a location of a recoverable metal-bearing material in the heap, wherein the metal-bearing material comprises iron and at least one other metal value, delivering a leaching solution from a leaching solution source to a leaching solution regulating system, wherein the leaching solution comprises an effective amount of citric acid and hydrogen peroxide, regulating at least one of a pressure, a mass flow rate, or a volumetric flow rate of the leaching solution to achieve a target operational condition, wherein the target operational condition is selected to optimize a set of operational parameters to maximize recovery of the at least one other metal value, delivering the leaching solution at the target operational condition from the leaching solution regulating system to the subsurface leaching distribution system, and delivering the leaching solution at the target operational condition from the subsurface leaching distribution system to the location of the recoverable metal-bearing material under a surface of the heap to leach and recover the at least one other metal value.