Copper, an ancient metal, still supports human civilization today. From high-voltage transmission lines to
the inside of microchips, from household appliances to new energy vehicles, high-purity electrolytic copper
is everywhere. It is the conductor of choice for power transmission, the basic material for the electronics industry,
and an indispensable strategic resource for energy transformation. And it all starts with a sophisticated
electrochemical purification journey - electrolytic refining.
Why electrolysis? The inevitable choice from crude copper to high
purity copper
The purity of crude copper obtained after smelting and blowing the ore is usually between 98% and 99.5%. This seemingly
high purity is not enough for modern industry. Trace amounts of arsenic, bismuth, antimony, nickel and other impurities can
seriously degrade copper's electrical conductivity, ductility and corrosion resistance, making it unsuitable for use in areas
with demanding material properties.
The core purpose of electrolytic refining is to completely remove these “black sheep” impurities and produce high-grade
copper cathodes with a purity of 99.99% (or even 99.999%) or more, to meet the extreme needs of high-end manufacturing.
This process is not only purification, but also a precise separation of resources, which can efficiently recover gold, silver,
platinum, selenium and other valuable rare metals.
The core of electrolysis: a well-designed “copper migration”
Electrolytic refining is an ambitious electrochemical project, and its core equipment is a huge electrolyzer. The
whole process can be summarized as “dissolution at the anode, precipitation at the cathode”.
Preparation of the raw materials: First, the crude copper from the fire-refining process is cast into heavy anode plates.
At the same time, pure copper sheets are used to make the starting sheet, which serves as the base for the cathodic
precipitation of copper.
Electrolyte: The electrolytic tank is filled with electrolyte composed of sulfuric acid and copper sulfate, which is the
“highway” for copper ion migration.
Electrification reaction: when the direct current, in the anode, the copper in the crude copper and more active than
copper metal impurities (such as iron, zinc) to lose electrons, in the form of ions dissolved into solution. The inactive
precious metals such as gold and silver, as well as selenium, tellurium and other substances that are difficult to dissolve,
are dislodged from the anode and sink to the bottom of the tank, forming valuable anode mud.
At the cathode, the copper ions in the solution preferentially get electrons and are reduced to metallic copper, which
is evenly deposited on the starting pole piece, with the copper layer thickening and eventually forming the high-purity
cathode copper with smooth surface and dense structure. And those metal ions which are more active than copper will
stay in the electrolyte due to the potential problem and will not be precipitated at the cathode, thus realizing the
efficient separation of copper and impurities.
Beyond tradition: revolutionizing the permanent cathode process
The traditional electrolysis process uses copper starter electrode sheets as cathodes, which need to be made and stripped
repeatedly, making the process cumbersome. The permanent cathode process is now commonly used in mainstream
advanced plants.
This process uses a smooth, non-adhesive titanium or stainless steel plate as the permanent cathode. Copper precipitates
and grows into a thick sheet on the cathode plate, which is then stripped off in its entirety by a specialized stripping unit to
form the final product. The cathode plate itself is cleaned and returned to the electrolyzer for reuse. This technology greatly
improves the level of mechanization and automation, enhancing production efficiency and the quality of high-purity copper
cathode products.
Resource Recycling and Green Manufacturing
The modern copper electrolysis plant is not simply a metal processing workshop, but also a model of resource recycling.
Anode mud “gold panning”: the precipitated anode mud is the main raw material for refining precious metals such as gold,
silver, platinum, palladium and other rare metals such as selenium and tellurium, which is of great value and an important
source of economic benefits for the electrolysis process.
Electrolyte purification: The impurity ions (such as nickel and arsenic) accumulated in the electrolyte need to be processed
regularly through a set of independent purification system to recycle valuable elements, maintain the optimal chemical balance
of the electrolyte, and ensure the stable quality of copper cathode.
Energy saving and environmental protection: The application of new electrolyzer design, energy efficient power supply and
intelligent control system continuously reduces the energy consumption per unit of product. The closed management of the
whole process also effectively controls acid mist emission, realizing green and clean production.
Conclusion: Quality forges the future
Copper electrolysis, a seemingly traditional process, is still absorbing new technologies and concepts, and evolving
towards a more efficient, intelligent and environmentally friendly direction. It is not only a refining process that transforms
crude copper into high-purity materials, but also a cornerstone for safeguarding the security and stability of the supply chain
of national electric power, electronics, new energy and other key industries. That piece of high-purity copper cathode
glittering with rose gold luster carries the modern industry's unremitting pursuit of ultimate performance and pure quality,
and continues to conduct energy for the progress of human society and connect the future.