Oxidative Chloride Leaching for Gold Recovery
Solution Overview
Problem
Cyanide leaching is considered more effective for gold recovery, but chloride leaching is expensive due to high reagent consumption and faces challenges in gold recovery yield and corrosion issues from high chloride concentrations, limiting its commercial application.
Innovation Solution
A method involving oxidative chloride leaching with a solution containing cupric ions, chloride, and bromide at specific pH and oxidation potential to dissolve gold from gold-bearing raw materials, followed by liquid-liquid extraction and evaporation to recycle the leaching solution, eliminating the need for additional copper and reducing chemical consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If chloride leaching is used to recover gold, then the method can be applied as an alternative to cyanide leaching, but the reagent consumption increases and cost rises
Solution Approach 1:
The patent changes the chemical parameters of the leaching solution by introducing a specific composition ratio of cupric ions to chloride ions, maintaining cupric ion concentration between 2-20 g/l while chloride concentration is kept between 2-12% by weight. This parameter optimization reduces oxidant consumption while maintaining effective gold leaching, directly addressing the high reagent consumption problem of conventional chloride leaching
Solution Approach 2:
The patent creates a composite leaching system combining cupric chloride with additional chloride sources (such as sodium chloride, calcium chloride, or hydrochloric acid) to achieve synergistic effects. This composite approach enhances gold dissolution efficiency while controlling overall reagent consumption, resolving the contradiction between effectiveness and reagent usage
2Productivity
If high chloride concentration is used in leaching solution, then gold dissolution can be enhanced, but corrosion problems increase
Solution Approach 1:
The patent optimizes the chloride concentration parameter to a specific range of 2-12% by weight, avoiding both too-low concentrations that limit dissolution and too-high concentrations that cause severe corrosion. This parameter control allows effective gold leaching while minimizing corrosive effects on equipment
Solution Approach 2:
The patent introduces cupric ions as an intermediary oxidizing agent that facilitates gold dissolution through a different mechanism than direct chloride oxidation. The cupric ions act as a mediator in the leaching reaction, reducing the need for excessive chloride concentrations and thereby reducing corrosion while maintaining productivity
3Quantity of substance
If conventional chloride leaching is used, then gold can be leached from ore, but the recovery yield is lower than cyanide leaching
Solution Approach 1:
The patent employs a composite leaching system combining cupric chloride with additional chloride sources, creating a synergistic effect that enhances gold recovery yield. The cupric ions provide oxidation capability while chloride ions maintain gold in solution, achieving recovery efficiency comparable to or exceeding cyanide leaching
Solution Approach 2:
The patent utilizes cupric ions as a strong oxidizing agent to accelerate gold dissolution. The cupric ions efficiently oxidize metallic gold to soluble gold complexes, significantly improving recovery yield and making the process more reliable and efficient compared to conventional chloride leaching methods
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 achieves high gold recovery yields of over 70% and allows for the concurrent recovery of silver, reducing costs and environmental impact by maximizing chemical circulation and minimizing copper addition.
Implementation Method 1
oxidative chloride leaching in an aqueous leaching liquor... the aqueous leaching liquor contains dissolved cupric ions (Cu2+) which act as an oxidizing agent
Implementation Method 2
chloride leaching... leaching with a mixture containing a mixture of halides... The mixture of halides in the leaching preferably comprises chloride and bromide
Implementation Method 3
gold recovery step, wherein gold is recovered from the gold-containing solution... by liquid-liquid extraction
Implementation Method 4
evaporation to recycle the leaching solution
Data Source
Figure 1
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AI summary
The invention relates to a method for preparing a gold- containing solution by chloride leaching from gold-bearing raw materials. A further object of the invention is to provide a method for recovering gold and optionally silver from the prepared gold-containing solution. The invention relates also to a process arrangement for recovering gold and optionally silver.