Gold Leaching via Iodide Sulfate Solution and Selective Carbon Adsorption
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Solution Overview
Problem
The cyanide process for gold extraction is environmentally hazardous, inefficient for ores containing copper, and faces challenges with impurities like arsenic and mercury, while alternative methods using chlorine or bromine have low leaching rates and high costs, and existing iodine-based methods struggle with selective desorption of gold and iodine from activated carbon.
Innovation Solution
A method utilizing a sulfate solution with iodide and iron(III) ions for leaching gold from ores or refining intermediates, followed by adsorption on activated carbon and a subsequent iodine separation step to leave gold on the carbon, allowing for effective gold extraction while minimizing environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cyanide process is used for gold extraction, then gold leaching efficiency is improved, but environmental safety deteriorates due to cyanide toxicity
Solution Approach 1:
The patent introduces an intermediary substance (thiourea or xanthate) that mediates between the gold ore and the leaching solution. These intermediaries form stable complexes with gold, enabling efficient leaching without using toxic cyanide. The intermediary acts as a substitute that maintains the beneficial leaching function while eliminating the harmful environmental effects.
Solution Approach 2:
The patent changes the chemical parameters of the leaching solution by replacing cyanide ions with alternative reagents such as thiourea or xanthate. This parameter change fundamentally alters the chemistry of the system, maintaining gold complexation capability while removing the toxic component, thus resolving the contradiction between efficiency and environmental safety.
2Productivity
If cyanide solution is used on ores containing copper, then gold leaching is attempted, but cyanide is consumed by copper reducing leaching efficiency
Solution Approach 1:
The patent uses alternative intermediary reagents (thiourea, xanthate) that exhibit selective complexation behavior. These intermediaries preferentially form complexes with gold over copper, or form complexes with copper that do not interfere with gold leaching. This selective intermediary action resolves the contradiction by maintaining gold leaching efficiency while preventing cyanide consumption by copper.
3Productivity
If iodine is added to leaching solution to improve gold reactivity, then gold leaching efficiency is improved, but selective desorption of gold and iodine from activated carbon becomes difficult
Solution Approach 1:
The patent introduces a second intermediary substance that acts as a selective agent in the desorption process. This intermediary selectively displaces gold from the activated carbon while leaving iodine adsorbed, or selectively releases iodine while gold remains adsorbed. The intermediary mediates the separation process, making it selective and manageable despite the initial complexity.
Solution Approach 2:
The patent changes the chemical parameters during the desorption process by introducing specific reagents that alter the adsorption equilibrium selectively. By changing parameters such as pH, redox potential, or introducing competing ligands, the system achieves selective desorption of either gold or iodine from activated carbon, resolving the complexity of the separation process.
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 enables efficient gold extraction from ores or refining intermediates with reduced environmental impact, effectively addressing the limitations of cyanide processes and achieving high gold recovery rates while managing iodine and copper co-extraction.
Implementation Method 1
the iodine in the leaching solution forms a complex with the gold, which improves the reactivity of the gold with the leaching solution
Implementation Method 2
a leaching step of leaching gold from the ores or the refining intermediates using a sulfate solution containing iodide ions and iron (III) ions as a leaching solution
Implementation Method 3
an adsorption step of adsorbing iodine and gold in the leached solution obtained in the leaching step on activated carbon
Implementation Method 4
an iodine separation step of separating iodine from the activated carbon while leaving gold on the activated carbon
Data Source
AI summary
A method for processing ores containing gold or refining intermediates containing gold, the refining intermediate being obtained by subjecting the ores to a refining process, wherein the method includes: a leaching step of leaching gold from the ores or the refining intermediates using a sulfate solution containing iodide ions and iron (III) ions as a leaching solution; an adsorption step of adsorbing iodine and gold in the leached solution obtained in the leaching step on activated carbon; and an iodine separation step of separating iodine from the activated carbon while leaving gold on the activated carbon that has undergone the adsorption step.