Walking into a modern copper processing plant, the most shocking scene is often the electrolysis
workshop - neatly arranged in the giant electrolysis tanks, hanging several meters long copper anode
plate and paper-thin copper starting pole piece, the tank turquoise-blue electrolyte flows slowly, the
current works silently, a few days later, the cathode will be deposited on the thickness of a uniform,
bright surface like a mirror of the pure copper plate. Copper plate. This is the core process of copper
electrolytic refining, which purifies crude copper to more than 99.99%.
The transformation of crude copper: from anode to electrolyte
The first step in copper electrolytic refining is to cast the crude copper (about 99% pure) from the fire
refining process into regular anode plates. These anode plates contain precious metals such as gold and
silver as well as small amounts of impurities. They are suspended in an electrolytic bath filled with a
mixture of copper sulfate and sulfuric acid, along with a thin sheet of pure copper with a clean surface
(the starting pole piece).
When the direct current is turned on, a marvelous change occurs:
Copper atoms on the anode plate lose electrons and become copper ions that dissolve into the electrolyte.
Copper ions in the solution migrate to the cathode, gain electrons and are reduced to pure copper atoms
Precious metals (gold, silver) and selenium tellurium and other impurities do not dissolve, sinking into the “anode mud”.
Iron, nickel, arsenic and other impurities will dissolve, but not deposited through the additive control
The core of the process: the precise dance between the current and
the solution.
The efficient and stable operation of copper electrolytic refining relies on the precise control of three key elements:
Electrolyte formulation management
Copper sulfate provides a source of copper ions, while sulfuric acid enhances electrical conductivity. Continuously
monitor and adjust the copper-acid concentration, temperature (typically 45-55°C), and circulation flow rate to ensure
ion migration efficiency and deposition quality. A purge system is required to treat impurities as they accumulate.
Current efficiency optimization
Current density (current intensity per unit area) directly affects yield and quality. Too high a current density can lead to
cathode roughness and tumor growth, while too low a current density can reduce efficiency. Modern factories use
automatic control systems to stabilize the current density of each plate in the range of 280-320A/m², with current
efficiency as high as 95-98%.
Additives precisely regulated
Trace additives are the key to obtaining dense and flat copper cathodes:
Gums (gelatine, etc.): refine crystalline particles and improve densification.
Thioureas: enhance surface gloss and inhibit dendritic crystallization.
Chloride ions: improve additive synergies and facilitate impurity separation
From cathode to high-end applications: extending the value of
high purity copper
After 7-12 days of electrolytic deposition, the copper cathode is automatically stripped to a thickness of 6-8 mm.
these are Grade A copper (Cu-CATH-1) with a purity of 99.99%:
Cut into copper ingots and rods for high-end cables and electromagnetic wires
Calendered into copper foil, which becomes the core material for lithium batteries and electronic circuits.
Processed into precision copper tubes and copper alloys for refrigeration, shipbuilding and aerospace.
Green Metallurgy: Continuous Upgrading of Environmental
Protection and Efficiency
Modern copper electrolytic refining is accelerating the green transformation:
Energy-saving design: new insoluble anodes (e.g. titanium-based coating) reduce energy consumption by 15%.
Intelligent control: Internet of Things (IoT) real-time monitoring of tank voltage and temperature to dynamically
optimize parameters.
Full recovery of resources: anode sludge enriched with gold, silver, platinum group metals; electrolyte purification
to recover nickel and arsenic.
Low-carbon cycle: green power application and zero wastewater discharge technology are gradually promoted.
In the copper electrolysis refining workshop, the low sound of direct current and the mechanical sound of overhead
cranes are intertwined, and tens of thousands of tons of high-purity copper are born here. When a piece of red copper
is transformed into a rose-colored high-purity copper cathode, it will soon be used in thousands of households - from
the micron-sized circuits of cell phone chips to the ultra-high-voltage cables that span mountains and rivers. This
century-old process, in the course of continuous innovation, is providing the most basic and critical “copper” cornerstone
for green energy, artificial intelligence and high-end manufacturing.