Waste Metal Recovery Using Segmented Ammonia and Thiosulfate Leaching
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Solution Overview
Problem
Existing methods for recovering copper, gold, and other valuable metals from waste materials, particularly E-waste, are inefficient and costly.
Innovation Solution
A method involving ammonia-based lixiviant for leaching copper and base metals, followed by electrowinning, and thiosulfate leaching for noble metals, with countercurrent flows in each circuit to enhance recovery efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single leaching method is used to recover all metals from waste materials, then the process is simpler, but the recovery efficiency and purity of individual metals deteriorates
Solution Approach 1:
The patent divides the metal recovery process into two separate leaching circuits: a first leaching circuit using ammonia-based lixiviant for base metals (copper, nickel, cobalt) and a second leaching circuit using thiosulfate-based lixiviant for precious metals (gold, platinum). This segmentation allows each circuit to be optimized for specific metal types, improving recovery efficiency and purity while maintaining manageable process complexity through modular design.
2Ease of operation
If conventional single-circuit leaching is used, then the equipment and operation are simpler, but the separation precision and purity of recovered metals deteriorates
Solution Approach 1:
The patent implements separate leaching circuits for base metals and precious metals, enabling selective recovery and high-purity separation. The first circuit recovers base metals with high efficiency, while the second circuit specifically targets precious metals, achieving superior separation precision that would be impossible in a single mixed circuit.
Solution Approach 2:
The patent uses a solid-liquid separator as an intermediary between the two leaching circuits. This separator divides the treated waste material stream, directing base metal-containing residues to the first circuit and precious metal-containing residues to the second circuit, thereby enabling precise metal separation while maintaining operational simplicity through standardized separation equipment.
3Ease of manufacture
If traditional metal recovery methods are used, then the process cost is lower in terms of equipment investment, but the overall cost-effectiveness and recovery value deteriorates due to lower efficiency
Solution Approach 1:
The patent employs segmented leaching circuits with metal-specific reagents (ammonia for base metals, thiosulfate for precious metals), maximizing the recovery value of each metal type. This approach improves cost-effectiveness by ensuring high recovery rates of valuable precious metals while using readily available, low-cost reagents, thereby achieving superior returns on equipment investment compared to conventional single-circuit 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
Enhances the recovery of copper and noble metals from waste materials with improved efficiency and reduced costs by utilizing ammonia and thiosulfate leaching processes.
Implementation Method 1
contacting a waste material feed stream with a first ammonia-based lixiviant adapted to leach copper and other base metals
Implementation Method 2
ammonia leaching in the first leaching circuit to leach the copper and the other base metals
Implementation Method 3
thiosulfate leaching in the second leaching circuit to leach the at least one noble metal from the treated waste material feed stream
Implementation Method 4
using Cu2+ as an oxidant for (a) leaching the copper and the other base metals from the waste material feed stream
Implementation Method 5
using electrowinning in the recovering of the copper metal from the first ammonia-based lixiviant
Implementation Method 6
using a precipitation reaction, such as a Merrell Crowe reaction, for the recovery of gold from the second lixiviant
Data Source
AI summary
A method for recovering metals from waste materials includes steps of contacting a waste material feed stream with a first lixiviant adapted to leach copper and other base metals from the waste material feed stream and provide a treated waste material feed stream, recovering copper metal from the first lixiviant, contacting the treated waste material stream with a second lixiviant adapted to leach noble metals from the treated waste material feed stream and recovering gold from the second lixiviant.