Gold Recovery via Halide Leaching in Copper Hydrometallurgy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for recovering gold from residues containing iron and sulfur in copper hydrometallurgical processes are inefficient, often requiring high oxidation-reduction potentials that lead to the dissolution of sulfur, increasing costs and complexity.
Innovation Solution
A method involving leaching gold from a copper (II) chloride and alkali chloride solution with controlled oxidation-reduction potential (600-650 mV) and pH (0.5-2.5) using divalent copper and oxygen, with the addition of bromide to accelerate gold dissolution without exceeding the oxidation-reduction potential, allowing for efficient gold recovery while keeping sulfur undissolved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high oxidation-reduction potential is used to leach gold from sulphur-containing materials, then gold dissolution is improved, but sulfur dissolves which increases costs and complexity
Solution Approach 1:
The patent applies parameter changes by precisely controlling the oxidation-reduction potential within a specific range (650-750 mV) and pH below 0, creating optimal conditions for gold dissolution while preventing sulfur dissolution. This quantitative parameter control resolves the contradiction by finding the precise operational window where gold is leached efficiently without triggering harmful sulfur dissolution.
Solution Approach 2:
The patent uses copper(II) chloride or iron(III) chloride as intermediary oxidizing agents to facilitate gold dissolution. These intermediaries enable gold oxidation at controlled potentials below the threshold that causes sulfur dissolution, thus resolving the contradiction by providing a mediated oxidation pathway that selectively targets gold without affecting sulfur.
2Productivity
If conventional gold leaching methods are used, then gold recovery is achieved, but the process is slow and requires high oxidation potential
Solution Approach 1:
The patent changes key parameters including oxidation-reduction potential (650-750 mV), pH (below 0), and temperature (raised pressure conditions) to optimize the leaching kinetics. These parameter modifications accelerate gold dissolution rates significantly, reducing leaching time while maintaining selective gold recovery without requiring excessively high oxidation potentials.
Solution Approach 2:
The patent employs strong oxidizing agents (copper(II) chloride or iron(III) chloride) under controlled conditions to accelerate gold oxidation. This accelerated oxidation approach speeds up the leaching process dramatically compared to conventional methods, resolving the time efficiency contradiction while maintaining selective gold dissolution.
3Speed
If high oxidation potential is applied to leach gold, then gold dissolution is accelerated, but iron and sulfur dissolve increasing solution complexity
Solution Approach 1:
The patent implements precise parameter control with oxidation-reduction potential maintained at 650-750 mV and pH kept below 0, creating a selective chemical environment. These parameter settings accelerate gold dissolution kinetics while establishing thermodynamic conditions that prevent iron and sulfur dissolution, thus resolving the contradiction between dissolution speed and substance loss.
Solution Approach 2:
The patent creates local quality differences in the leaching environment by maintaining specific pH and potential conditions that are favorable for gold oxidation but unfavorable for iron and sulfur dissolution. This localized optimization of chemical conditions enables selective fast gold leaching without co-dissolution of other elements.
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 significantly shortens gold leaching time and maintains sulfur in its elemental form, reducing costs associated with sulfur removal and improving the overall efficiency of gold recovery.
Implementation Method 1
The oxidation-reduction potential is adjusted to the range of 650 - 750 mV... Copper (II) chloride or iron (III) chloride is added to the suspension to oxidise the gold contained in the raw material, whereupon it dissolves
Implementation Method 2
the oxidation-reduction potential is a maximum of 650 mV... The gold contained in the waste or intermediate is leached by means of divalent copper, oxygen and bromide
Implementation Method 3
a small amount of bromide accelerates the time required for the gold to dissolve... The feed of bromide accelerates gold dissolution without causing the oxidation-reduction potential of the leaching to rise above the value of 650 mV
Implementation Method 4
the pH value of the solution is adjusted to the range of 0.5 - 2.5... In these conditions the iron does not yet dissolve and the sulphur remains largely undissolved
Implementation Method 5
the oxidation-reduction potential is regulated with oxygen in the range of 600 - 650 mV vs. Ag/AgCl electrode... In these conditions the iron does not yet dissolve and the sulphur remains largely undissolved
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a method for recovering gold in connection with the hydrometallurgical production of copper from a waste or intermediate product containing sulphur and iron that is generated in the leaching of the copper raw material. The recovery of both copper and gold occurs in a chloride environment. The gold contained in the waste or intermediate is leached by means of divalent copper, oxygen and alkali bromide in a solution of copper (II) chloride and alkali chloride, in conditions where the oxygen-reduction potential is a maximum of 650 mV and the pH a minimum of 0.5. The bromide accelerates the dissolution of the gold.