Amino Acid Leaching for Copper and Precious Metal Recovery
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Solution Overview
Problem
Current hydrometallurgical processes for recovering copper and precious metals, such as gold and silver, face challenges due to the use of toxic, expensive, and environmentally hazardous reagents like cyanide, which are inefficient and costly, especially when dealing with low-grade ores or ores with high copper content, leading to excessive reagent consumption and environmental concerns.
Innovation Solution
An alkaline leaching process using amino acids, such as glycine, and hydrogen peroxide as environmentally friendly reagents, which form stable complexes with metals, enhancing solubility and allowing for selective recovery of copper and precious metals, particularly effective in alkaline conditions with controlled pH and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cyanide is used as a leaching reagent for gold and silver recovery, then extraction capability is improved, but toxicity and environmental hazard increase
Solution Approach 1:
The patent replaces cyanide with alternative lixiviants including thiosulfate, thiocyanate, halides, and thiourea systems. These alternatives are positioned as shorter-lived, less persistent solutions that maintain extraction capability while reducing long-term environmental persistence and toxicity concerns
Solution Approach 2:
The patent addresses the harmful effects of cyanide by converting to alternative chemical systems that, while still requiring careful handling, offer reduced toxicity profiles. The thiosulfate-copper-ammonia system and other alternatives transform the chemical approach from highly toxic to moderately hazardous, enabling continued metal recovery with improved environmental outcomes
2Productivity
If cyanide is used for leaching copper and precious metals, then metal recovery is improved, but reagent cost increases
Solution Approach 1:
The patent develops leaching systems that can simultaneously recover multiple metals (copper, gold, silver) using the same lixiviant system. The thiosulfate-copper-ammonia system and halide-based systems are designed to handle mixed metal ores, eliminating the need for separate processing streams and reducing overall reagent consumption and costs
Solution Approach 2:
The patent optimizes lixiviant composition and process parameters to improve extraction efficiency while reducing reagent consumption. By adjusting pH, temperature, and lixiviant concentration, the system achieves high metal recovery with reduced reagent dosages, making the process more economically viable
3Productivity
If conventional cyanidation is used for copper-gold ores, then gold extraction is improved, but cyanide consumption increases due to copper interference
Solution Approach 1:
The patent applies selective leaching strategies where different lixiviants are used to target specific metals. The thiosulfate-copper-ammonia system and other alternatives provide selective dissolution that can preferentially extract gold or copper based on ore composition, reducing the consumption of expensive reagents by avoiding non-selective cyanide attack on all metals
Solution Approach 2:
The patent inverts the conventional approach by using copper-containing lixiviants (such as copper-thiosulfate-ammonia systems) that leverage copper as a beneficial component rather than treating it as interference. This inverted chemistry allows copper to participate constructively in the leaching mechanism, improving gold extraction while eliminating cyanide consumption issues
4Object-affected harmful factors
If alternative inorganic lixiviants are used instead of cyanide, then toxicity is reduced, but selectivity and solubility performance worsen
Solution Approach 1:
The patent employs composite lixiviant systems combining multiple chemicals (thiosulfate + copper + ammonia, or halides + complexing agents) to achieve both reduced toxicity and improved selectivity. These composite systems leverage synergistic interactions between components to provide selective metal dissolution while maintaining environmental acceptability
Solution Approach 2:
The patent uses complexing agents and auxiliary chemicals as intermediaries to enhance the performance of alternative lixiviants. These intermediary substances improve metal solubility and selectivity by forming stable complexes, bridging the gap between the reduced toxicity of alternative lixiviants and the high performance previously achieved only with cyanide
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 process reduces reagent costs, minimizes environmental impact, and improves the efficiency of metal recovery, enabling the effective extraction of copper and precious metals from low-grade ores and concentrates with reduced downstream processing complexities and costs.
Implementation Method 1
amino acids, such as glycine, and hydrogen peroxide as environmentally friendly reagents, which form stable complexes with metals, enhancing solubility
Implementation Method 2
hydrogen peroxide as environmentally friendly reagents, which form stable complexes with metals
Data Source
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AI summary
A process for recovery of metal comprising copper and/or a precious metal from a metal containing material, including the steps of: leaching the metal containing material with an alkaline lixiviant and an amino acid or derivative thereof in order to produce a metal containing leachate; and extracting the metal from the leachate.