Copper cathode, i.e. high purity copper (usually containing ≥99.95% copper) obtained from electrolytic
refining, is the core raw material for electric power, electronics, new energy and other fields. Its production
process integrates the essence of metallurgy, chemistry and engineering technology, which directly determines
the quality and application value of the final product. This article will systematically analyze the production
process of copper cathode, technical core and industry trends, to provide practical reference for practitioners.
Raw material preparation: from crude copper to anode plate
Copper cathode production takes crude copper (containing 98%~99.5% of copper) produced by pyrometallurgy
as raw material. Crude copper is firstly remelted by smelting furnace and cast into anode plate with uniform
specification. In this process, the melting temperature (about 1150℃) and mold design should be strictly
controlled to ensure uniform thickness and flat surface of the anode plate, so as to avoid short-circuit or uneven
dissolution in the subsequent electrolysis process.
electrolysis refining: the core link of purification
Electrolysis is the core stage of copper cathode production, and its essence is to separate copper and impurities
through electrochemical reaction.
Electrolysis tank configuration:
The anode plate (crude copper) and cathode substrate (pure copper initiator plate or stainless steel permanent
cathode) are suspended alternately in the electrolysis tank, which is filled with electrolyte containing copper sulfate
and sulfuric acid. In modern plants, large parallel tanks are used, which can accommodate dozens of electrodes in a
single tank, significantly increasing production capacity.
Electrolysis reaction control:
When DC current is applied, the anode crude copper is dissolved into copper ions (Cu²⁺), which are reduced to
pure copper by gaining electrons on the surface of the cathode, and deposited layer by layer to form copper
cathode. Key process parameters include:
Current density: typically 220~320 A/m², too high results in rough crystallization, too low reduces efficiency;
Electrolyte composition: maintain copper ion concentration (4050 g/L), sulfuric acid concentration (150200 g/L)
and temperature (50~65°C);
Additives: gelatin, thiourea, etc. are used to refine cathode crystallization and improve physical quality.
Impurity treatment and anode mud recovery:
The precious metals such as gold, silver, selenium, tellurium and other impurities such as arsenic, antimony, etc.
in the crude copper settle to the bottom of the tank to form “anode mud”, which can be centrally recovered for
refining and become an important source of value-added by-products. The electrolyte needs to be purified
regularly to remove the accumulated ionic impurities (such as nickel and iron) and keep the solution active.
copper cathode post-treatment and finished ingot casting
After the end of the electrolysis cycle (usually 712 days), the copper cathode is deposited to a standard
weight (about 60,150kg per piece), removed and passed through:
Washing and stripping: high-pressure water jet rinses the electrolyte from the surface and mechanically strips
the copper from the permanent cathode plate;
Melting and casting molding: part of the copper cathode is directly sold as a product, and the other part is
remelted by the reflecting furnace and cast into the form of wire ingot, bar billet, etc., to meet the downstream
processing needs.
the direction of technological evolution and innovation
The traditional process continues to be optimized, and the emerging technology accelerates the application:
Permanent cathode technology: stainless steel cathode replaces starting pole piece, automated stripping
improves efficiency and reduces labor cost;
Energy-saving design: high-frequency switching power supply replaces silicon rectifier, saving 10%~15%;
optimization of tank circulation system reduces heat loss;
Intelligent control: sensors monitor electrolyte composition and temperature in real time, AI algorithm
dynamically adjusts current density to prevent short circuit and polarization;
Environmental upgrading: closed acid mist collection and wastewater recycling system become the standard
for new plants.
Industry Value and Challenges
The purity of copper cathode directly affects wire conductivity, ductility and corrosion resistance, and is the quality
cornerstone of high-end applications such as power grid construction, electric vehicles and chip packaging. The
industry is currently facing challenges such as low-grade ore processing, rising energy costs and environmental
standards, and future process innovation will focus on:
Efficient treatment of complex raw materials (such as high arsenic copper ore);
Development of low-carbon technologies such as low-temperature electrolysis and oxygen pressure leaching;
Industry chain synergy (e.g. precise extraction of valuable elements in anode mud).
Conclusion
Copper cathode production process is a deep combination of traditional metallurgy and modern engineering
technology, and its technological progress has always been centered on the three major cores of “purity, efficiency
and green”. With the global energy transition and the development of the electronics industry, the demand for
high-end copper materials will continue to grow, driving the refining process to a smarter and more sustainable
direction. Understanding the details and trends of this process is of practical importance to those involved in the field.