Oxidized copper ores are an important part of copper resources,
which are widely distributed in major mining areas around the
world. Unlike copper sulfide ores, copper in copper oxide ores
exists in the form of carbonates (such as malachite CuCO₃-Cu(OH)₂),
oxides (such as hematite Cu₂O), hydroxysilicates (such as silica
malachite CuSiO₃-2H₂O) and sulphates (such as cholecalciferite
CuSO₄-5H₂O). These minerals are chemically active, and the traditional
pyrometallurgical process is inefficient and polluting, so the modern
industry commonly adopts the hydrometallurgical process
(leaching-solvent extraction-electrowinning, abbreviated as SX-EW)
for high-efficiency extraction, which is also applicable to the treatment
of mixed resources of sulfide minerals, such as chalcopyrite (Cu₂S). In
this paper, we will deeply analyze the processing flow and technological
breakthrough of copper oxide ore, and discuss its key role in resource
utilization and sustainable development.
I. The core steps of the hydrometallurgical
process of copper oxide ores
Leaching process: efficient dissolution under acidic environment
The leaching of copper oxide ores is usually carried out with sulfuric
acid, hydrochloric acid, or microbial-assisted acidic solutions. During
heap or tank leaching, the acidic solution reacts with the ore to
release copper ions (Cu²⁺) from the mineral lattice into the liquid phase.
Solvent extraction: precise separation of copper ions
The leach solution contains impurity ions such as iron and aluminum,
which need to be selectively purified by solvent extraction techniques.
Organic extractants (e.g. hydroxamic compounds) combine with copper
ions to form complexes, which are transferred to the organic phase, and
then copper ions are re-released to the aqueous phase through
counter-extractants (e.g. high concentration of sulfuric acid), resulting in
a high-purity copper sulfate solution, which removes more than 99%
of the impurities and lays the groundwork for subsequent electrowinning.
Electrodeposition purification: Scale production of copper cathode
The purified electrolyte enters the electrodeposition tank, with lead alloy
as the anode and stainless steel as the cathode, and under the action of
direct current, the copper ions are reduced to copper metal on the surface
of the cathode. The electrowinning process needs to control the current
density (200-300A/m²), temperature (40-50°C) and electrolyte circulation
speed to optimize the quality of copper cathode crystallization and reduce
energy consumption. The DC power consumption per ton of copper
cathode is about 2,000-2,500kWh.
II. Technological Challenges and Innovative Directions
Complex Mineral Processing and Resource Recovery Rate Enhancement
Some oxidized copper ores are coexisting with sulphide ores and chalcopyrite
minerals, which are difficult to be dissociated efficiently by traditional leaching
processes. In recent years, the application of ammonia leaching (for alkaline minerals)
and bioleaching technology (utilizing Thiobacillus ferrooxidans) has significantly
improved the adaptability of complex minerals. For example, ammonia leaching
systems can selectively dissolve copper at pH 9-11, while inhibiting the leaching
of impurities such as iron and silicon.
Optimizing Environmental Protection and Energy Consumption
Although wet metallurgy reduces sulfur oxides by more than 80% compared to
thermal processes, acidic waste treatment remains a challenge. The industry is
promoting zero-emission systems: heavy metals are recovered through
neutralization and precipitation, and the residual liquid is recycled for the leaching
process; at the same time, photovoltaic/wind power supply and waste heat
recovery devices are introduced to reduce the carbon footprint of electrowinning.
Low-grade Ore and Tailings Reuse
For low-grade oxide ores with less than 0.5% copper content, In-situ Leaching (ISL)
reduces mining and crushing costs by injecting leach solution directly into the ore
layer. In addition, the process of extracting residual copper (containing 0.1%-0.3%
copper) from historical tailings has entered the commercialization stage, which
can extend the life cycle of the mine for 10-15 years.
C. Industrial Value and Future Trends of Oxidized
Copper Ore Extraction
About 25% of global copper production comes from oxidized and mixed ores,
and the maturity of hydrometallurgical technology has enabled resource countries
such as Chile, Peru, and the Democratic Republic of the Congo (DRC) to develop
low-grade deposits. According to statistics, the SX-EW process can reduce the
production cost of tons of copper by 30%-40% compared with the thermal
process, and is suitable for small and medium-sized mines in remote areas. As the
demand for copper from the electric vehicle and renewable energy industries
surges (with an expected shortfall of 6 million tons by 2030), the efficient use
of copper oxide ores will be the key to alleviating supply pressure.
In the future, the development of intelligent control systems (e.g. AI real-time
optimization of leaching parameters) and green chemical reagents
(biodegradable extractants) will further drive the industry's transformation
towards high efficiency and low carbon. Meanwhile, the development of
non-traditional resources such as deep-sea polymetallic nodules and
tailings regeneration may reshape the global copper supply chain pattern.
Conclusion
Wet extraction of oxidized copper ores represents the innovative direction
of the modern metallurgical industry, and its low-pollution and highly
adaptable features perfectly fit the sustainable development goals of the
global mining industry. By continuously optimizing the process chain and
expanding the resource boundary, this field will provide a solid material
guarantee for the global energy transition and industrial upgrading.