As the world's third largest consumer metal, copper smelting process innovation has a direct impact
on the development level of basic industries such as electricity, electronics and construction. In this
paper, we will analyze the core processes of the two major technology routes of thermal and wet
processes, and reveal how modern copper smelting plants can achieve efficient, clean and
sustainable production.
Strategic positioning of copper smelting industry
Resource and Demand Pattern
The world's proven copper resources reserves exceed 880 million tons, with an annual mining capacity of
22 million tons, 85% of which are processed through pyrometallurgical refining. The new energy industry
is driving the surge in demand, with each electric car consuming 3 times more copper than traditional
cars, and photovoltaic systems requiring 5,000 tons of copper per GW installed capacity.
Comparison of process economics
Pyrometallurgical smelting applies to sulfide ore (grade >0.5%), with a processing cost of about US$1,200
per ton of copper; wet smelting treats oxide ore (grade 0.2%-0.8%), with a cost reduction of 40%. The
proportion of recycled copper is increased to 35%, and the energy consumption of smelting is only
15% of that of virgin ore.
Environmental technology inflection point
Sulfur capture rate increased from 95% to 99.9% and SO₂ emission per ton of copper reduced to less than
8kg with double flash smelting technology. The power consumption of electrolysis has been optimized
from 2,800kWh/t to 2,200kWh/t, reaching the international advanced level of clean production.
Pyrometallurgical smelting core process analysis
1. Concentrate pretreatment system
Raw material mixing: mixing concentrates from different mines, controlling copper grade 20%-30%, sulfur
25%-30%, iron 25%-35%.
Drying and dewatering: rotary kiln reduces moisture from 12% to 0.3%, and increases thermal efficiency to 78%.
Pelletizing and molding: adding bentonite binder, pellet size of 2-4mm, improving the efficiency of melting
pool reaction.
2. Flash melting revolution
Reaction mechanism: CuFeS₂ + O₂ → Cu₂S-FeS (ice copper) + SO₂↑
Process Parameters:
Reaction temperature 1250-1300℃
Oxygen Concentration 70-95
Material residence time <2 seconds
Technical breakthrough:
Central diffusion type spray gun design, melting intensity up to 80t/(m²-d)
Copper recovery rate of 98.5%, slag containing copper down to 0.6
3. Converter blowing and refining
Multi-stage control:
Slagging period: adding quartz flux, Fe oxidation to generate FeSiO₃ slag
Copper period: Cu₂S oxidized to crude copper (98.5% Cu)
Intelligent blowing and smelting:
Sonar probe to monitor melt height in real time
Dynamically adjusted blast air volume (200-400Nm³/min)
End point copper grade control accuracy ±0.2%.
4. Anode refining and electrolysis
Reflection furnace refining:
Oxidization and desulfurization at 1150℃, copper liquid purity up to 99.3%.
Phosphorus copper master alloy addition of 0.03%-0.05% to improve casting performance.
Permanent cathode electrolysis:
Electrolyte composition: Cu²⁺ 45g/L, H₂SO₄ 180g/L, temperature 60-65 ° C
Current density 300-340A/m², copper cathode purity up to 99.99%.
The efficiency of automatic flaking system is increased to 20 pieces/minute
Wet smelting technology system
1. Heap leaching-extraction-electrowinning (SX-EW)
Heap leach field design:
Multi-layer liner system (HDPE + bentonite) to prevent seepage
Spray intensity 5-10L/(m²-h), leaching cycle 180-300 days
Solvent extraction:
LIX984N extractant, copper recovery＞95%
Reverse extraction acidity 180-200g/L H₂SO₄
Electrodeposition workshop:
Stainless steel cathode initiator sheet, current efficiency 92%-95
Power consumption of 2000-2200kWh per ton of copper
2. Bio-leaching technology breakthrough
Bacterial strain cultivation:
Acidophilic oxidized ferrous thiobacillus (At. ferrooxidans)
Arsenic-resistant strain tolerance concentration>5g/L
Reaction control:
pH 1.5-2.0, ORP 650-750mV
Leaching rate: 85%-90% for secondary copper sulfide ore
Primary copper sulphide ore 70%-75
Environmental Protection and Resource Recycling
Exhaust gas treatment system
Acid production device:
Double-contact acid production system, SO₂ conversion rate>99.85%.
Tail gas SO₂concentration <100mg/Nm³
Particulate matter control:
Electrostatic precipitator (ESP) efficiency 99.8%
Emission concentration of baghouse dust <10mg/Nm³
Zero wastewater discharge system
Graded treatment:
Heavy metal wastewater: sodium sulfide precipitation + ion exchange
Acidic wastewater: lime neutralization + RO membrane separation
Water recycling rate:
Pyro system＞90%
Wet process system >85
Solid Waste Resource Utilization Path
Slag utilization:
Containing 40% of iron slag to make mineral wool fiber
Water quenching slag as cement replacement material (mixing amount 30%-40%)
Anode sludge treatment:
Precious metal recovery: Au>99%, Ag>98%, Pt>95
Selenium-tellurium extraction purity up to 99.9
Three major directions of technology upgrading
1. Low-carbon process innovation
Hydrogen-based reduction: Hydrogen replaces coke, reducing carbon emissions in the reduction section by 85%.
Oxygen-rich side-blowing smelting: energy consumption per ton of copper reduced to 380kgce,
reaching the international leading level.
2. Smart Factory Construction
Digital twin system:
Real-time simulation of melting temperature field, prediction deviation＜±5℃.
Electrolyzer voltage balancing AI control, power saving 5%-8
Unmanned transportation:
AGV copper mold handling system, 40% increase in operational efficiency
3. Adaptability to complex raw materials
Multi-metal synergistic extraction:
Simultaneous recovery from 2% copper and 0.3% cobalt ore.
Copper and cobalt recovery rate of 92% and 85% respectively.
High arsenic copper ore treatment:
Solidification / stabilization technology, arsenic leaching toxicity <1mg / L
Conclusion
The evolution of copper smelting technology is essentially a double transformation of efficiency
improvement and green transformation. From reflector furnace to double-flash smelting, from
open electrolysis to permanent cathode process, every technological breakthrough promotes
the industrial energy efficiency leap. Facing the goal of carbon neutrality, smelting companies
need to focus on building a “low-carbon smelting - intelligent control - multi-metal recovery
” trinity technology system, and turn the copper smelting process into a model of efficient
resource utilization. In the future, the deep integration of hydrometallurgy, biometallurgy
and digital twin technology may redefine the industrial paradigm of copper smelting.