Copper Leaching with Halides to Reduce Acid Consumption
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Solution Overview
Problem
Current methods for recovering copper from copper-bearing sulfide ores require high temperatures and pressures, leading to high sulfuric acid concentrations in the pregnant leach solution, making solvent extraction expensive and less efficient, while using hydrochloric acid or high chloride concentrations results in decreased copper extraction yields.
Innovation Solution
A hydrometallurgical method that optimizes leaching conditions for copper-bearing sulfide ores under atmospheric or slightly elevated pressure and mild temperatures in a sulfuric acidic solution with alkali metal or earth metal halides, achieving high copper and precious metal recovery without the need for additional neutralization steps and with low chloride concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperatures and pressures are used to leach copper from sulfide ores with sulfuric acid, then copper dissolution is improved, but sulfuric acid concentration increases excessively requiring costly neutralization
Solution Approach 1:
The patent changes the chemical parameters of the leaching system by introducing chloride ions (NaCl) to form copper-chloride complexes. This alternative complexation pathway allows copper dissolution at lower temperatures and acid concentrations, resolving the contradiction between dissolution rate and acid consumption.
Solution Approach 2:
Chloride ions act as an intermediary that facilitates copper dissolution by forming stable copper-chloride complexes. This intermediary mechanism enables efficient leaching under milder conditions, reducing the need for high sulfuric acid concentrations and expensive neutralization steps.
2Temperature
If hydrochloric acid or high chloride concentration is used to leach copper, then leaching can be performed at reduced temperature and pressure, but copper extraction yield decreases in solvent extraction
Solution Approach 1:
The patent optimizes chloride concentration to a specific range (30-115 g/L) that enables low-temperature leaching while maintaining compatibility with subsequent solvent extraction. This parameter optimization resolves the contradiction by finding the optimal balance point where both temperature reduction and extraction yield are achieved.
3Productivity
If high sulfuric acid concentration is present in pregnant leach solution, then copper dissolution is enhanced, but solvent extraction becomes expensive due to excessive neutralization requirements
Solution Approach 1:
Chloride ions serve as an intermediary that enables copper dissolution through alternative complexation mechanisms, reducing dependence on high sulfuric acid concentrations. This intermediary approach maintains dissolution efficiency while minimizing acid consumption and associated neutralization costs.
Solution Approach 2:
The patent changes the chemical environment by introducing chloride ions, which alter the dissolution mechanism from sulfuric acid-dependent to chloride-complex-dependent. This parameter change reduces sulfuric acid consumption and subsequent neutralization costs while maintaining copper dissolution efficiency.
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 method allows for high-yield recovery of copper and precious metals like silver without the need for neutralization, reducing operational costs and enabling direct recovery from copper-bearing sulfide ores, while maintaining low chloride concentrations.
Implementation Method 1
leaching copper-bearing ore and/or concentrate under atmospheric or slightly pressurized conditions at a temperature below the boiling point of the leach solution in a sulfuric acidic solution in the presence of one or more alkali metal or alkali earth metal halides, whereby the total halide concentration is from 30 to 115 g/L, to dissolve copper
Implementation Method 2
Copper is purified by solvent extraction from the first aqueous pregnant leach solution to obtain a first copper-containing loaded organic solution and a first aqueous raffinate
Implementation Method 3
The copper containing loaded organic solution is stripped and copper is recovered from a stripping solution that contains trace amounts of chlorides
Data Source
AI summary
Provided is a method of recovering copper and one or more precious metals comprising leaching copper-bearing ore and/or concentrate under atmospheric or slightly pressurized conditions at a temperature below the boiling point of the leach solution in a sulfuric acidic solution in the presence of one or more alkali metal or alkali earth metal halides, whereby the total halide concentration is from 30 to 115 g/L, to dissolve copper and to obtain a leaching liquor comprising copper, sulfur species, and halides in solution. The leaching liquor is then subjected to a solid-liquid separation after which a first aqueous pregnant leach solution and a copper depleted leaching residue are obtained. Copper is purified by solvent extraction from the first aqueous pregnant leach solution to obtain a first copper-containing loaded organic solution and a first aqueous raffinate. The copper containing loaded organic solution is stripped and copper is recovered.