Sulfur Dioxide Depolarized Anode for Copper Electrowinning
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Solution Overview
Problem
The high electrical energy consumption in metal electrowinning processes, particularly in sulfate-based electrolytes, is a significant challenge due to the energy-intensive oxygen evolution reaction at the anode, which accounts for over 25% of the total energy requirement in copper production.
Innovation Solution
The implementation of sulfur dioxide depolarized electrolysis (SDE) reduces the cell voltage by using sulfur dioxide to depolarize the anode reaction, lowering the energy required for metal electrowinning, with sulfur dioxide being introduced into the anolyte or supplied directly to the anode, and using titanium or gold-coated anodes to facilitate the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If oxygen evolution reaction is used at the anode in sulfate-based electrolytes, then metal electrowinning can proceed, but electrical energy consumption increases significantly
Solution Approach 1:
The invention changes the chemical reaction parameters at the anode by introducing sulfur dioxide, transforming the oxygen evolution reaction into a sulfur dioxide oxidation reaction. This parameter change reduces the standard electrode potential from +1.23 V to +0.17 V, thereby significantly lowering the electrical energy consumption and cell voltage required for metal electrowinning
Solution Approach 2:
Sulfur dioxide acts as an intermediary substance that mediates the anode reaction. By introducing SO2 into the anolyte or directly to the anode, it serves as a depolarizing agent that facilitates electron transfer at lower energy costs, replacing the conventional oxygen evolution pathway and reducing energy loss
2Power
If conventional anodes are used in metal electrawinning, then the process can operate, but cell voltage remains high leading to high electrical power consumption
Solution Approach 1:
The invention modifies the electrochemical parameters of the anode system by changing the reaction mechanism from oxygen evolution to sulfur dioxide oxidation. This parameter change reduces cell voltage by approximately 50%, thereby reducing electrical power consumption while maintaining operational simplicity through the use of standard electrowinning cell infrastructure
3Use of energy by moving object
If sulfur dioxide depolarized electrolysis is implemented, then cell voltage and energy consumption decrease, but the process requires additional sulfur dioxide supply infrastructure
Solution Approach 1:
Sulfur dioxide serves as a chemical intermediary that enables the depolarized electrolysis process. The invention integrates SO2 supply into the existing electrolyte circulation system, where SO2 is introduced into the anolyte stream, allowing the intermediary to be delivered through modified but not fundamentally new infrastructure
Solution Approach 2:
The sulfur dioxide serves multiple functions: it acts as a depolarizing agent at the anode, serves as a source of additional sulfuric acid production, and can be integrated with existing sulfuric acid manufacturing processes. This multi-functionality reduces the need for separate dedicated infrastructure
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 decreases the cell voltage and electrical power consumption by approximately 50% in copper electrowinning, eliminating oxygen evolution at the anode and reducing environmental impacts, while also improving cathode quality and eliminating anode sludges.
Implementation Method 1
Anodic oxidation of SO2 is used to depolarize the anode reaction and to decrease the energy required for electrowinning
Implementation Method 2
sulfur dioxide oxidation reaction (3) has a much lower standard electrode potential than oxygen evolution: SO2(diss)+2H2O(1)→H2SO4(aq)+2H+(aq)+2e−
Implementation Method 3
the metal is extracted as it is deposited onto the cathode
Implementation Method 4
In metal electrawinning a current is passed from an inert anode to a cathode through a liquid leach solution containing said metal so that the metal is extracted as it is deposited onto the cathode
Implementation Method 5
the oxygen evolution reaction, caused by electrolytic splitting of water into protons and oxygen
Data Source
AI summary
The invention relates to a method for electrowinning a metal from an electrolyte in an electrowinning cell that comprises an electrolysis tank, one or more anodes, and one or more cathodes, which anodes and cathodes are housed in the electrolysis tank. The method comprises supplying sulfur dioxide to the anode to depolarize the anode process and to reduce the energy consumption of the electrowinning cell.