From the power lines that connect millions of homes to the communication networks that support
cities, from energy-efficient new-energy vehicles to sophisticated electronic chips, copper is an
ancient metal that plays an indispensable role in modern society. However, from the raw copper
ore extracted from mines to the final pure copper material that meets the stringent industrial standards,
it needs to undergo a precise and complex transformation journey - this is the copper refining process.
The copper refining process is divided into two core processes:
fire refining and electrolytic refining.
Fire refining: preliminary purification in the flames
In the fire refining stage, crude copper (usually containing about 98% copper and a variety of impurities) is
sent to a high-temperature kiln to melt. At this point, the air or oxygen-enriched air that is blown in plays a
key role. At high temperatures, the iron, lead, zinc, sulfur and other impurity elements in the molten copper
combine more readily with oxygen than copper to form an oxide slag. Experienced operators precisely control
the temperature, the degree of oxidation and the atmosphere in the furnace, guiding these impurity slags to the
surface of the melt, where they are carefully skimmed off. Although this step significantly improves the purity of
the copper, it is still difficult to completely remove precious metals such as gold, silver, selenium, tellurium or trace
impurities. The purity of fire-refined copper (anode copper) obtained at this point has usually reached 99.2%-99.7%,
which is ready for the next stage of deep purification.
Electrolytic refining: perfect purity sculpted by electric current
Electrolytic refining is the central step in achieving high purity copper. Copper anodes are cast into heavy anode
plates, which are immersed together with cathode plates, also made of thin sheets of pure copper, into huge
electrolytic baths filled with copper sulfate electrolyte. When a strong direct current passes through the tank, the
magical electrolysis process begins: the copper atoms on the anode plate lose electrons and become copper ions
dissolved into the solution, while the copper ions in the solution gain electrons on the cathode plate and revert to
pure copper atoms, which are uniformly and densely deposited on the cathode plate in one layer. The copper cathode
with a purity of more than 99.99% is born.
In this process, those precious metals and impurity elements that are difficult to remove in the pyrolysis stage, because
they cannot be dissolved or deposited as effectively as copper under electrolysis conditions, eventually settle at the
bottom of the electrolyzer in the form of anode mud. These precious anode slimes are important secondary resources
for refining rare elements such as gold, silver, platinum, palladium, selenium and tellurium.
Environmental protection and efficiency: the dual pursuit of processes
While pursuing high purity, modern copper refineries regard the efficient utilization of resources and environmental
protection as equally important:
Exhaust gas treatment: The sulfur-containing flue gas generated in the thermal refining is efficiently collected and converted
into industrial sulfuric acid through the advanced acid production system, realizing the recovery of sulfur resources and the
reduction of pollutant emissions.
Wastewater Recycling: The copper-containing wastewater generated in the electrolysis workshop is treated strictly, the copper
element is effectively recovered, and the purified water is recycled in large quantities, which significantly reduces the consumption
of fresh water.
Waste slag valorization: The slag produced by the thermal refining process can be used as building materials after treatment,
and the precious anode sludge is sent to a special workshop to extract a variety of high-value metal elements from it.
Energy optimization: Through the waste heat recovery system, the heat in the high-temperature flue gas is efficiently converted
and utilized, significantly reducing the overall energy consumption.
The copper refining process, like a master craftsman, gives copper a new lease of life with the heat of fire and the precision of
electricity. It is not only a key link in the industrial chain, but also a powerful witness to the realization of resource recycling and
sustainable development in modern industry. From the mines to thousands of households, behind every shiny copper wire, the
wisdom and sweat of this precision craft are condensed, silently supporting the light and connection of modern civilization.