Heap Bioleaching Sulfate Control for Sulfidic Copper Ores
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Solution Overview
Problem
Conventional heap leaching methods for copper-containing sulfidic ores result in low copper recovery due to the formation of a passive film on the ore surface, limiting extraction to 20-40 wt.%, and are inefficient for low-grade ores, especially when high sulfate concentrations hinder microbial activity.
Innovation Solution
A microbial-assisted heap leaching process that controls sulfate concentration in the leach liquor by monitoring and adjusting parameters such as aeration rate, pH, and temperature, using thermophilic microorganisms to operate at elevated temperatures up to 85°C, and adding microbes during agglomeration to regenerate ferric ions and acid, even at high sulfate levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional heap leaching is used to extract copper from sulfidic ores, then the process is simple and low-cost, but copper recovery is limited to 20-40 wt.% due to passive film formation
Solution Approach 1:
The patent changes the chemical parameters of the leach liquor by controlling sulfate concentration within 2-50 g/L and maintaining specific pH ranges (1.5-3.5), which prevents passive film formation and enables sustained microbial activity for higher copper recovery
Solution Approach 2:
The patent introduces microorganisms as intermediary agents that facilitate copper dissolution through bioleaching mechanisms, where microbes produce acids and oxidants that break down the passive film and dissolve copper from sulfidic ores
2Object-generated harmful factors
If high sulfate concentration is present in the leach liquor, then acid generation is enhanced, but microbial activity is inhibited
Solution Approach 1:
The patent optimizes the sulfate concentration parameter to a specific range (2-50 g/L) that balances acid generation benefits while preventing microbial inhibition, and controls pH (1.5-3.5) to maintain optimal conditions for both acid production and microbial survival
3Productivity
If thermophilic microorganisms are used to operate at elevated temperatures, then copper extraction rate increases, but process control complexity increases
Solution Approach 1:
The patent raises the temperature parameter to thermophilic ranges (45-85°C) to accelerate microbial metabolism and copper extraction kinetics, while implementing control systems that monitor and adjust temperature, pH, and sulfate concentration to manage the increased process complexity
4Reliability
If aeration rate is increased to enhance oxygen supply for microbial activity, then ferric ion regeneration improves, but energy consumption increases
Solution Approach 1:
The patent optimizes the aeration rate parameter to provide sufficient oxygen for microbial respiration and ferric ion regeneration while minimizing energy consumption, balancing the trade-off between metabolic activity and operational cost
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
Enhances copper extraction from sulfidic ores and waste materials by maintaining microbial activity and ferric ion regeneration, allowing for higher copper recovery despite high sulfate concentrations, achieving up to 85°C operation.
Implementation Method 1
microbes to oxidise ferrous ions and oxidise solid and soluble sulfur compounds, thereby regenerating ferric ions and acid
Implementation Method 2
using thermophilic microorganisms to operate at elevated temperatures up to 85°C
Implementation Method 3
The leaching process requires an acid and an oxidant to dissolve copper into solution
Implementation Method 4
aerated through direct injection of air via aeration pipes extending into the heap
Implementation Method 5
supplying an acidic leach liquor to a heap of fragments or agglomerates of fragments
Data Source
AI summary
Microbial-assisted heap leaching of fragments or agglomerates of fragments of copper-containing sulfidic ores, such as chalcopyrite ores, and copper-containing sulfidic waste materials is disclosed. A heap leaching method includes controlling the sulfate concentration in a leach liquor. When heap leaching includes using agglomerates, a method of forming agglomerates includes adding the feed materials at, or close to, the inlet end, typically no more than 40%, typically no more than 30%, more typically no more than 20%, of the length from the inlet end of the agglomeration unit.