In the process of human industrial civilization, copper purification technology has always played a key
role. When 99% of crude copper is transformed into 99.99% pure copper through electrolytic
purification, this silver-red metal has gained the energy to change the modern industrial landscape.
From the nano-scale conductive channel inside the chip, to the giant wire of the extra-high voltage
transmission network, electrolytic copper with its excellent conductivity and ductility, constructed a
modern industrial system of “metal neural network”.
Atomic-level transformation of electrolytic purification
The essence of electrolytic purification is to use the difference in electrochemical properties of metals to achieve
elemental separation. The anode plate containing 98.5% -99.5% copper immersed in copper sulfate electrolyte,
under the action of the DC electric field, copper atoms preferentially lose electrons to form Cu ² ⁺ into the solution,
precious metals and other impurities deposited as anode mud. On the surface of the cathode titanium plate, copper
ions are reduced to pure metal at the atomic level, and this “atomic screening” process can increase the purity of
copper to more than 99.995%.
The electrolyte system is the core carrier of the process. Modern refining systems use a composite electrolyte of
190-220g/L copper sulfate and 140-180g/L sulfuric acid, with the temperature strictly controlled at 60-65℃. The
addition of colloidal additives (e.g. gelatin, thiourea) makes the cathode deposition denser and the current
efficiency is increased to over 98%. Intelligent monitoring system adjusts Cl- concentration at 30-50mg/L in real
time to ensure optimal crystal growth along the (220) crystal plane.
Current density control demonstrates process precision. The conventional process utilizes a current density of
280-320A/m², while the new cycle reverse current technology increases efficiency by 40%. In semiconductor-grade
high-purity copper production, pulsed current technology (frequency 100Hz, duty cycle 1:4) to refine the grain
size to 0.8μm, surface roughness reduced to Ra0.1μm.
Precision Symphony of Processes
Anode pretreatment determines the upper limit of purification. Rough copper anode needs to go through
double-sided milling (cutting amount 3-5mm), edge chamfering (radius 5mm), ultrasonic cleaning (40kHz) and
other processes, and the surface cleanliness needs to reach Sa2.5 grade. In the production of copper for nuclear
power, the anode plate also needs to be vacuum annealed (650℃×4h) to eliminate internal stress.
The design of the electrolyzer contains industrial wisdom. The modern compound electrolyzer is made of PPH
material, loaded with 42 anode plates in a single tank, with the distance between poles controlled at 90-100mm.
the cathode/anode area ratio is accurate at 1.1:1, and with the labyrinth type circulating pipeline, the flow rate
of electrolyte can be stabilized at 15L/min-m², and the gradient of copper ions concentration is no more than
5 percent.
The cathode stripping technology witnesses the evolution of the process. 10mm thick copper cathode formed by
36 hours of deposition is processed by the automatic stripping system of titanium master plate, and the bending
stress is controlled to be less than 2MPa. The laser thickness measurement system monitors the uniformity of
deposition in real time, compressing the thickness tolerance to ±0.05mm and increasing the yield to 99.9%.
Technical revolution of purity leap
Three-stage purification system to create the ultimate purity. The electrolyte is successively filtered by bag filter
(precision of 5μm), resin adsorption (nickel, arsenic removal), electrodialysis decontamination (removal of Sb, Bi),
and the total amount of metal impurities is reduced to less than 0.5ppm. In the production of 6N high-purity
copper, a 0.01μm ceramic membrane ultrafiltration system is also added to realize molecular-level purification.
Crystallization control technology breaks through the physical limit. Magnetic field-assisted electrolysis technology
(0.5T static magnetic field) improves the consistency of copper grain orientation by 60% and increases the
electrical conductivity by 3% IACS. ultrasonic cavitation technology (20kHz) breaks the boundary layer of the
solution, and the deposition rate is increased to 0.45mm/h, which is 1.8 times faster than that of the traditional process.
Intelligent control system reshapes production standards. The digital twin platform simulates 2000 electrolyzer
working conditions in real time, and the AI algorithm predicts concentration fluctuations 6 hours in advance.
The cathode process online monitoring system (LIBS technology) realizes ppm-level detection of 30 kinds of
elements, and the quality traceability is accurate to each cathode plate.
Purity Revolution for Cross-Industry Applications
The electronics industry pursues extreme purity. 5G communication base station heat dissipation substrate adopts
ultra-pure copper with an oxygen content of <5ppm, and the thermal conductivity is raised to 401W/(m-K).
Oxygen-free copper strips (99.999% purity) for chip encapsulation undergo a combined electrolysis-area melting
process, which reduces the density of impurities at grain boundaries to 10³/cm², and reduces signal transmission
loss by 45%.
New energy field opens up a brand new battlefield. Power battery lug material is purified by electrolysis to obtain
<0.1° cubic weave, and the overcurrent capacity is increased by 30%. Tinned copper strips for photovoltaic have
improved creep resistance by 5 times after electrolysis and hot rolling, and are suitable for 1500V high-voltage systems.
High-end equipment manufacturing performance breakthroughs. Fusion device superconducting magnets with RRR
value (residual resistance ratio) of 300 ultra-high-purity copper, so that the critical current density increased to
5000A/mm². Aerospace wires purified by electrolysis, strength-conductivity matching value (σ × IACS)
exceeded 6000, weight reduction benefit of 40%.
Double Evolution of Green Smart Manufacturing
Resource recycling system builds new ecology. The recovery rate of precious metals from anode mud breaks through
99.9%, and 1 ton of anode mud can extract 3kg of gold and 30kg of silver. The electrolyte closed-circuit recycling
system integrates diffusion dialysis and electrodeposition technology, the utilization rate of water resources reaches
98%, and the unit consumption of sulfuric acid is reduced to 0.3t/t copper.
Clean energy transformation reduces carbon footprint. The photovoltaic DC power supply system directly drives the
electrolyzer, reducing energy consumption by 15%. Waste heat recovery device converts electrolyte waste heat into
low-pressure steam, meeting 30% of the plant's heating demand. In the zero-carbon plant practice, the proportion
of green electricity has been raised to 85%.
Pollution control technology reaches new heights. Acid mist capture system (made of glass fiber reinforced plastic)
with three-stage alkali washing, fluoride emission concentration <0.5mg/m³. Heavy metal wastewater is treated by
chelating precipitation-RO membrane, and the concentration of copper ion is stabilized at below 0.1mg/L, which is
better than the standard of surface Ⅲ water.
From traditional fire refining to modern electrolytic purification, the path of copper purification has witnessed the
evolutionary trajectory of human industrial civilization. When 5N-grade high-purity copper in the quantum
computer to transmit information, when the regeneration of copper in the recycling economy renewed new
life, this century-old technology is intelligent, green, sophisticated new form, continue to write the “King of Metals”
legend. Driven by the needs of semiconductors, new energy, high-end equipment and other emerging fields,
electrolytic copper purification technology will continue to break through the boundaries of purity and efficiency,
and provide human industrial civilization with a metal footnote that will never fade.