Subsurface Raffinate Injection for Low-Permeability Heap Leaching
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Solution Overview
Problem
Conventional surface heap leaching operations are ineffective in liberating certain metal values due to low permeability caused by high clay content materials and jarosite precipitation, and lack the ability to regulate flow conditions, leading to non-uniform leaching and reduced recovery rates.
Innovation Solution
A subsurface leaching system with pressure, flow, and volume control, combined with residual metal mapping, delivers additive-enhanced solutions like citric acid and hydrogen peroxide to targeted locations and depths within leach heaps, optimizing recovery by identifying ore targets and adjusting operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional surface heap leaching is used, then the process is simple to operate, but metal recovery is reduced due to low permeability caused by high clay content materials and jarosite precipitation
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 core of the heap where low permeability zones are located, bypassing the surface permeability problems caused by clay and jarosite precipitation.
Solution Approach 2:
The system implements localized injection points at specific locations within the heap based on permeability assessment. Different zones receive tailored injection strategies, with injection parameters (flow rate, pressure, solution composition) adjusted to match local heap conditions, thereby optimizing metal recovery in previously inaccessible low permeability areas.
2Device complexity
If leaching solution is delivered without flow regulation, then the system is simpler, but non-uniform leaching occurs leading to reduced recovery rates
Solution Approach 1:
The system incorporates flow meters, pressure sensors, and level detectors that continuously monitor injection parameters and heap conditions. This feedback information is used by the control system to automatically adjust pump speeds, valve positions, and injection rates to maintain uniform leaching conditions across different zones of the heap.
Solution Approach 2:
The injection system is designed with dynamically adjustable parameters including variable flow rates, controllable injection pressures, and adjustable injection timing. These dynamic capabilities allow the system to adapt to changing heap conditions during the leaching process, ensuring uniform solution distribution and maximizing metal recovery.
3Productivity
If subsurface injection system is implemented with flow regulation, then metal recovery is maximized, but device complexity increases
Solution Approach 1:
The control system serves multiple functions: it monitors flow rates, regulates injection pressure, controls pump operations, and adjusts valve positions all through a single integrated platform. This multi-functionality reduces the need for separate control devices for each parameter, thereby managing complexity while achieving uniform leaching and maximizing metal recovery.
4Quantity of substance
If jarosite precipitation is not controlled, then the process requires no additional additives, but permeability decreases and leaching efficiency is reduced
Solution Approach 1:
The system addresses the harmful effect of jarosite precipitation by introducing additives that modify the precipitation behavior. These additives transform the harmful jarosite scale into more benign precipitates or control its formation in a way that maintains heap permeability while still allowing effective metal leaching to proceed.
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
This approach maximizes metal recovery by ensuring uniform leaching and minimizing jarosite precipitation, improving permeability and recovery rates in non-homogeneous ore heaps.
Implementation Method 1
A subsurface leaching system with pressure, flow, and volume control delivers additive-enhanced solutions like citric acid and hydrogen peroxide to targeted locations and depths within leach heaps
Implementation Method 2
conventional hydrometallurgical processes for copper recovery involve leaching metal bearing materials with an acidic solution
Implementation Method 3
The resultant process stream—the pregnant leach solution—is recovered, and a processing step such as solution extraction is used to form a highly concentrated and relatively pure metal value containing aqueous phase
Implementation Method 4
regulating at least one of a pressure, a mass flow rate, or a volumetric flow rate of the leaching solution to achieve a first target operational condition
Implementation Method 5
Conventional surface heap leaching operations may be unable to liberate certain metal values from the ore as a result of low permeable materials such as high clay content materials present in the heap
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.