Copper Electrorefining Cell Voltage and Gas Agitation Control
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Solution Overview
Problem
Current copper electrorefining processes face challenges in maintaining high purity and productivity due to anode passivation and contamination issues caused by high impurity levels in copper anodes, leading to increased voltage and current density requirements, which can result in lower cathode quality and reduced economic viability.
Innovation Solution
The process involves maintaining a voltage difference of less than 1.6 volts between the anode and cathode, using anodes with copper content up to 98%, a current density of at least 180 A/m², and an electrolyte refreshing rate of 30-1900% per hour, with gas introduction into the cell to enhance electrolyte agitation and remove anode slimes effectively, thereby controlling impurity levels and improving cathode quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher current density is used to maintain productivity, then copper deposition rate increases, but voltage increases which causes more metals to deposit on cathode reducing purity
Solution Approach 1:
The patent applies parameter changes by operating at elevated current densities (up to 400 A/m²) while simultaneously controlling voltage within a specific range (0.2-0.6 V) to prevent excessive polarization. This allows high productivity to be achieved without the voltage increase that would otherwise cause unwanted metal deposition and reduce cathode purity.
2Power
If higher voltage difference is applied to compensate for electrical resistance, then current flow is maintained, but other metals start to deposit on cathode lowering purity
Solution Approach 1:
The patent resolves this contradiction by changing the voltage parameter to operate within an optimized range (0.2-0.6 V) that compensates for electrical resistance without exceeding the threshold where unwanted metal deposition occurs. This controlled voltage approach maintains current flow while preserving cathode purity.
3Adaptability or versatility
If anodes with higher impurity levels are used, then feedstock flexibility improves, but anode passivation increases reducing electrorefining efficiency
Solution Approach 1:
The patent applies parameter changes by operating at elevated current densities and controlling voltage within specific ranges, which prevents anode passivation even when using anodes with higher impurity levels. This allows the process to maintain high electrorefining efficiency while accepting more contaminated feedstocks, thereby improving feedstock flexibility.
Solution Approach 2:
The patent ensures continuous useful action by maintaining optimal voltage and current density parameters that prevent anode surface passivation. This continuous operation at optimized parameters allows efficient copper transfer from anodes with higher impurity levels without interruption or significant loss of productivity.
4Manufacturing precision
If voltage is kept within narrow range to ensure cathode purity, then metal deposition control is maintained, but productivity is limited
Solution Approach 1:
The patent resolves this contradiction by changing the operating parameters to elevated current densities (up to 400 A/m²) while maintaining voltage within the optimized range (0.2-0.6 V). This allows the process to achieve both high cathode purity and high productivity simultaneously, as the voltage control prevents unwanted metal deposition even at these higher current densities.
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 approach allows for the successful electrorefining of copper from lower purity anodes with higher impurity levels, maintaining high cathode quality and productivity while reducing power consumption and operational costs, enabling the processing of more contaminated feedstocks and efficient recovery of valuable metals.
Implementation Method 1
copper is dissolved (primarily by electrochemically induced 'corrosion') from a less pure copper anode
Implementation Method 2
the metal depositing on the cathode may be controlled to be almost exclusively copper
Implementation Method 3
gas introduction into the cell to enhance electrolyte agitation and remove anode slimes effectively
Data Source
Figure 1
AI summary
Disclosed is a process for copper production comprising the electrorefining of copper in an electrolytic cell, wherein • the voltage difference over the cell is maintained at less than 1.6 volt, • the anode comprises at most 98.0%wt of copper and less than 1.00%wt of iron, • the current density through the cell is at least 180 A/m² of cathode surface, • electrolyte is removed from the cell during the operation at an average refreshing rate of 30-1900 % per hour, by overflow of a first stream of electrolyte over a cell wall, and • a gas is introduced into the cell and bubbled through the electrolyte in between anode and cathode. Further disclosed is a liquid molten metal composition suitable for copper anode electrorefining comprising at least 90.10%wt and at most 97%wt of copper, at least 0.1%wt of nickel, at least 0.0001%wt and less than 1.00%wt of iron, and 250-3000 ppm wt of oxygen.