Copper, an ancient metal that flows in the electrical vein, connects the information world and drives
the green energy revolution, has long been integrated into every inch of modern life. When you touch
the screen of your cell phone, when the current in thousands of households in the line rushing, when
the new energy car quietly drove through the streets - the back are inseparable from a special high-purity
copper. Its purity, from the initial 99% to a staggering 99.99% or more, this qualitative leap, not natural
ore can give, but depends on a sophisticated and important industrial magic: electrolytic copper refining.
After the fire refining of copper anode plate has a considerable degree of purity, but still residual gold,
silver, lead, tin and other trace impurities, like a diamond still need to be carved. The existence of these
impurities, seemingly insignificant, but enough to lay hidden dangers in future applications - a slight
decrease in conductivity, which may lead to the loss of power transmission efficiency; a slight lack of
toughness, will make the copper in the precision machining of the fracture risk is steeply increased.
The purity requirements of modern industry on copper are almost harsh, only through electrolytic refining
this “ultimate purification” process, can be forged to meet the high-end demand for industrial “golden veins”.
Core process: atomic-level purification driven by electric energy
Dissolution and Separation of Anode Plate:
A thick anode plate is pre-cast from crude copper (with a purity of about 99%) and immersed in a huge electrolytic
tank full of electrolyte (mainly composed of sulfuric acid and copper sulfate). When the direct current is switched on
and the current is driven, the copper atoms on the anode plate, unwilling to be bound, lose their electrons and are
converted into copper ions (Cu²⁺), which slowly dissolve into the electrolyte. At this time, those more “stubborn”
than copper precious metals (such as gold, silver, platinum) and some insoluble impurities (such as selenium,
tellurium), because it is not easy to lose electrons, can not be dissolved, have been off from the anode plate,
deposited in the bottom of the tank, forming a valuable anode mud (subsequent recovery of precious metals).
The base metal impurities (such as iron, nickel, zinc, lead, arsenic, antimony, bismuth, etc.), which are more
“active” than copper, can be dissolved into the solution, but they are subject to subsequent strict screening.
Electrolyte precision “control field”:
Electrolyte is not a simple acid-copper solution, it is the core medium of the entire refining process and “gatekeeper”.
Its composition (Cu²⁺ concentration, H₂SO₄ acidity), temperature, and the addition of additives (e.g., gelatin, thiourea,
chlorine ions) all need to be precisely controlled. These additives are like a smart “dispatcher”, can significantly
improve the quality of cathode deposition: they are adsorbed on the surface of the cathode, promote the uniform,
dense, flat deposition of copper ions, effectively inhibit the growth of rough dendrites and bumps, to ensure that
the final output of mirror-like, dense structure of the cathode copper sheet.
Pure new life" on the cathode:
Suspended parallel to the anode plate in the electrolyzer are thin, pure copper or stainless steel sheets with an
extremely smooth surface (known as starter sheets), which serve as the cathode. Driven by an electric field, Cu²⁺
ions in the electrolyte are attracted to the cathode, reach the surface, gain electrons, and are reduced back to copper
metal atoms, which are deposited layer by layer in an extremely homogeneous and dense manner on top of the
cathode. This reduction process is highly selective: only impurity ions (such as nickel, arsenic, antimony, etc.) with
standard electrode potentials close to or lower than copper may be precipitated along with a small amount; while
impurities with potentials much lower than copper (e.g., iron, zinc) will hardly be precipitated on the cathode; the
noble metal ions with potentials much higher than copper will be retained in solution or enter the anodic sludge.
After 7-14 days or even longer continuous deposition, the thickness of the copper cathode sheet increases
continuously, and finally forms a finished copper cathode plate weighing more than 100 kilograms with a
smooth and bright surface.
The “directional return” of impurities:
The concentration of base metal impurities (mainly nickel, arsenic, antimony) dissolved in the electrolyte
will gradually accumulate as electrolysis proceeds, and will affect the quality of copper cathode and current
efficiency if it is not controlled. Therefore, part of the electrolyte (called “waste electrolyte”) must be periodically
extracted for purification. The purification process usually includes neutralization and precipitation, extraction,
electrowinning and other methods to effectively remove impurities and recover valuable metals (e.g., nickel),
while replenishing fresh electrolyte and sulfuric acid to maintain the electrolyte composition in an optimal state
and ensure the continuous, stable and efficient operation of the refining process.
“Newborn” copper cathode: purity creates excellent quality
The purity of copper cathode produced after electrolysis is usually as high as 99.99% (4N) or more, and up to
99.999% (5N). This near-perfect purity gives it unrivaled characteristics:
Exceptional electrical conductivity: extremely low electrical resistivity, making it the conductor of choice for
power transmission and electronic components.
Excellent ductility: easy to draw, roll, stamping, to meet the needs of a variety of complex shapes processing.
Excellent thermal conductivity: widely used in heat sinks, heat exchangers and other high-efficiency thermal
conductivity components.
Stable chemical properties: good corrosion resistance and long service life.
Green and High Efficiency: The Eternal Pursuit of Modern Refining
Modern electrolytic copper refinery is not only the birthplace of pure copper, but also a practitioner of efficient
resource utilization and environmental friendliness:
Anode sludge: rich in precious metals such as gold, silver, platinum and palladium, and rare elements such as
selenium and tellurium, it is an important secondary resource, which can be efficiently recovered through a
specialized process and is of great value.
Waste electrolyte purification: not only removes harmful impurities and stabilizes the main process, but also
recovers nickel, copper sulfate and other by-products, realizing resource recycling.
Wastewater treatment: Heavy metal-containing wastewater undergoes advanced treatment (e.g. neutralization
and precipitation, membrane filtration, ion exchange, etc.) to ensure that it meets the standards for discharge or reuse.
Energy saving and consumption reduction: Continuously reduce energy consumption per unit of product by
optimizing current efficiency, tank voltage management, waste heat utilization and other technologies.
Driving the Future: Infinite Possibilities for High Purity Copper
As a basic raw material, high-purity copper cathode produced by electrolytic refining is being used in a wide
range of applications in line with the development of the times:
Electrical and electronic cornerstones: wires and cables, transformers, motor coils, copper cladding foil for
printed circuit boards (PCBs), and lead frames for integrated circuits.
New energy core: electric vehicle drive motor winding, charging pile cable, photovoltaic power generation
busbar, lithium battery copper foil collector.
High-end manufacturing: precision instrument components, high-efficiency heat exchanger tubes, high-end
building decoration materials.
Future technology frontier: 5G/6G communication high-frequency and high-speed materials, semiconductor
advanced packaging, superconducting material substrate, etc.
From the copper ore mined from the mine, to the crude copper smelted by fire, and finally transformed into
pure copper cathode in the quiet current of the electrolyzer - electrolytic refining, which is the core link of the
transformation of the “stone into gold”. It is not only a mature industrial technology, but also a key hub for
resource purification and recycling in modern industrial civilization. Every time the cathode plate on the uniform
deposition of copper layer, are more efficient energy transmission, more powerful electronic equipment, cleaner
transportation silently laid the foundation. As the flow of science and technology rushes forward, the demand for
copper purity and performance will continue to rise, and the electrolytic refining technology will continue to
improve on the road of high efficiency, intelligence, and greening, and continue to provide human civilization
with this indispensable “pure bloodline”.