Copper electrolytic refining is a crucial part of the modern metallurgical industry, which
converts crude copper into high-purity refined copper (usually with a purity of 99.99% or
more) through electrolysis to meet the demanding requirements of the electronics, electric
power, construction and new energy industries. This process not only improves the physical
and chemical properties of copper, but also realizes the effective separation and recovery of
impurity elements, which has both economic and environmental values. This article will systematically
introduce the principle, process, technical points and industrial significance of copper electrolytic refining.
The basic principle of electrolytic refining
Copper electrolytic refining is based on electrochemical principles. With crude copper as the anode
(rich in impurities), pure copper or stainless steel plate as the cathode, both immersed in copper sulfate
and sulfuric acid-rich electrolyte. After energized, the anode crude copper oxidation reaction, copper
atoms lose electrons to become copper ions (Cu ² ⁺) into solution; cathode reduction reaction occurs,
copper ions in the solution to obtain electrons to precipitate, the formation of high-purity copper. The
impurities with positive potential (such as gold, silver, platinum) do not dissolve and sink into the anode
mud, while the impurities with negative potential (such as iron, zinc) are retained in the electrolyte in ionic
form, and are subsequently removed through purification treatment.
Process flow and technical links
Anode preparation: the crude copper produced by pyrometallurgy is cast into anode plates, usually containing
98%~99.5% copper and a small amount of gold, silver, nickel, arsenic and other elements.
Electrolyzer operation: Multiple electrolyzers are connected in series to form a production line. The electrolyte
temperature is maintained at 5060℃ and circulates to ensure uniform concentration. The tank voltage is usually
0.20.3V and the current density is controlled at 200~300A/m² according to the process design.
Cathode deposition: The electrolysis cycle is about 1020 days, the cathode is gradually deposited to form
“copper cathode”, the thickness of which reaches 510mm, and then taken out, and then washed and dried
to be the finished product.
Electrolyte management: the concentration of copper ions in the electrolyte should be stabilized at 4050g/L,
and the concentration of sulfuric acid at 180200g/L. The accumulation of impurity ions (e.g. nickel, arsenic) affects
the electrolysis efficiency, so it is necessary to extract part of the electrolyte for purification and concentration on
a regular basis, and to replenish the new liquid.
Anode mud treatment: anode mud is rich in precious metals (gold, silver) and rare elements such as selenium,
tellurium, etc. It is an important by-product resource and can be recovered and refined separately.
Technology evolution and innovation
The traditional electrolysis process has problems such as high energy consumption and low current efficiency.
In recent years, the industry has improved efficiency through a number of technological innovations:
Permanent cathode technology: adopting stainless steel cathode to replace the traditional starting pole piece,
mechanized copper stripping to reduce labor cost and improve cathode flatness.
High current density electrolysis: Optimize the electrolyte flow field and additive formula to increase the current
density to more than 300A/m², which significantly increases the capacity of a single tank.
Automation control: real-time monitoring of electrolyte composition, temperature and tank voltage through
sensors, combined with big data algorithms to dynamically adjust parameters and reduce energy consumption fluctuations.
Environmental protection improvement: adopting a closed loop system to treat waste water and waste acid,
recovering valuable metals therein, and realizing near-zero discharge of waste liquid.
Industrial Value and Application Fields
Electrolytically refined copper is a basic material for high-end manufacturing:
Power industry: high conductivity makes it the core material for cables, transformers and motor windings.
Electronic industry: used in printed circuit boards, chip lead frames and other precision components.
New energy field: photovoltaic power generation and electric vehicles have a surge in demand for high-efficiency
copper, and the purity of electrolytic copper directly affects the performance of equipment.
Sustainable development: electrolytic refining can be combined with recycled copper recovery to refine and purify
copper scrap, reduce mineral dependence and promote circular economy.
Challenges and future trends
Despite the maturity of the technology, the process still faces challenges: energy consumption accounts for about
15% to 20% of total copper production, and the requirements for handling impurities such as arsenic and antimony
are becoming increasingly stringent. Future developments focus on:
Energy saving and consumption reduction: developing high efficiency electrode materials and low temperature
electrolysis process, utilizing green power to reduce carbon footprint.
Impurity control: deepen the research on electrolyte purification technology and improve the recovery rate of precious metals.
Intelligent upgrading: integrate IoT and AI technology to build a digital twin system for the whole process and realize
precise regulation.
As a century-old process, copper electrolytic refining continues to be revitalized through technological innovation. It
not only guarantees the stable supply of the global copper industry chain, but also interprets the future path of
traditional industry and sustainable development through the efficient utilization of resources and environmental
upgrading. For practitioners and investors, it is undoubtedly of great significance to pay attention to its
technological evolution and market dynamics.