As a core process of modern hydrometallurgy, leaching occupies a key position in the extraction of
non-ferrous metals such as copper, zinc and nickel. The process selectively dissolves the target metals
by chemical or biological means, provides high-grade raw materials for subsequent purification, and
directly affects smelting efficiency and resource utilization. This paper will systematically describe the
evolution of leaching technology and industrial practice.
Industrial positioning and technological evolution of leaching process
Analysis of the nature of the process
The leaching process is based on the solid-liquid reaction principle, using acidic/alkaline media or microbial
metabolites to transfer metal ions from ore/concentrate to the solution phase. Compared with traditional
pyrometallurgical smelting, it is characterized by low energy consumption (40%-60% reduction), applicability
to low-grade ores (0.5%-2% metal content), and significant environmental advantages.
Historical Technology Iteration
First generation: sulfuric acid heap leaching (1960s), copper recovery rate of 60%-70%
The second generation: high-pressure oxygen leaching (1980s), the decomposition rate of sulfide ore exceeded 90
The third generation: bioleaching (2000s), iron and sulfur oxidizing bacteria treatment of complex ore bodies
Fourth generation: nano-catalyzed leaching (2020s), reaction rate increased by 5-8 times
Economic and environmental value
More than 60% of the world's copper, more than 85% of uranium extracted by leaching process, each ton
of metal production water savings of 35 tons, emission reduction SO₂ 2.8 tons. Industrial waste metal residue
from 8% to less than 0.5%, resource utilization rate increased to 92%.
Comparison of mainstream leaching technology system
1. acid atmospheric leaching
Applicable minerals: oxidized copper ore (malachite, silica malachite)
Reaction equation: CuCO₃-Cu(OH)₂ + 2H₂SO₄ → 2CuSO₄ + CO₂↑ + 3H₂O
Control parameters: pH 1.5-2.0, liquid-solid ratio 4:1, temperature 25-40 ° C.
Innovation and improvement: ultrasonic-assisted crushing, penetration rate increased by 300%
2. alkaline pressurized leaching
Target: zinc sulfide concentrate (sphalerite), laterite nickel ore
Process conditions: temperature 150-230℃, oxygen partial pressure 700-1500kPa, NaOH
concentration 6-8mol/L
Efficiency breakthrough: zinc leaching rate of 98.5%, reaction time shortened to 2 hours
Equipment upgrade: titanium-tantalum alloy autoclave, corrosion-resistant life extended to 10 years.
3. Biological heap leaching system
Strain combination: At. ferrooxidans + Sulfolobus
Engineering parameters: heap height 8-10m, spray intensity 8-12L/m²-h, leaching cycle 120-180 days
Technical advantage: treating complex gold ore containing more than 3% arsenic, the gold recovery rate
is increased from 40% to 85%.
Intelligent control: implanted pH/ORP/temperature sensors, automatically adjust the ratio of bacterial liquid.
4. In-situ ground leaching technology
Application areas: sandstone uranium ore, deep-seated copper ore body
Liquid injection mode: step-well distribution, liquid injection intensity 0.5-1.5m³/h-m
Metal recovery: uranium concentration up to 200-500mg/L, solution upgrading rate >95%.
Environmental characteristics: 80% reduction of surface disturbance, no tailings storage
construction requirements
Industrial leaching system composition
Raw material pretreatment module
Three-stage crushing and screening: control the particle size of the ore at -10mm accounted for more than 90%.
Microwave activation treatment: the lattice destruction degree of sulfide minerals is increased by 60%, and the
leaching rate is doubled.
Surface modifier addition: sodium dodecyl sulfate (SDS) reduces slurry viscosity by 35%.
Reaction system design
Multi-stage countercurrent leaching: 4-6 stage tandem tanks, leach solution copper concentration
gradient from 0.8g/L to 35g/L.
Gas-liquid mixing enhancement: Venturi oxygen injection, dissolved oxygen concentration to maintain 8-12mg / L
Online monitoring system: XRF real-time analysis of the solution metal content, accuracy ± 0.02g / L
Solid-liquid separation unit
High-efficiency thickener: 30m diameter deep cone type, bottom stream concentration of 55% -60
Ceramic membrane filtration: pore size 0.1μm, filtrate suspension <50mg/L
Automated washing: three-stage countercurrent washing, metal loss rate <0.3
Environmental protection and resource recycling
Exhaust gas control
Acid mist treatment: glass fiber reinforced plastic (FRP) packing tower + screen mist eliminator, H₂SO₄
droplet capture efficiency >99.5%.
Volatile organic compounds: RCO catalytic combustion device, emission concentration <20mg/m³.
Wastewater reuse
Neutralization and precipitation: adjust pH to 8.5 with milk of lime, heavy metal removal rate＞99.9
Membrane separation system: nanofiltration + reverse osmosis combination, water reuse rate of> 85
Crystallization and salt separation: purity of sodium sulfate reaches 98%, which is sold as chemical raw material.
Solid Waste Resourcing
Utilization of leaching slag: slag with iron content >45% is made into iron powder, and those with
high SiO₂ are used as cement admixture.
Sludge treatment: plate and frame press filtration to the water content <18%, heavy metal stabilization and safe landfill
Four directions of technology upgrading
1. Intelligent reactor development
Microchannel reactor: 10 times higher efficiency than traditional tanks, 70% lower reagent consumption
Digital twin system: real-time simulation of leaching kinetics, optimization parameters response time <5 seconds
2. New leaching media
Ionic liquid: 1-butyl-3-methylimidazole tetrafluoroborate, 99.2% gold leaching rate
Supercritical CO₂: selective extraction with complexing agent, realizing zero wastewater discharge.
3. Bacterial strain genetic improvement
CRISPR gene editing: Improve the arsenic resistance of the strain to 5000mg/L.
High-temperature resistant engineering bacteria: adapt to 65-80℃ mine environment, shorten leaching cycle by 30%.
4. Process enhancement technology
Electric field assistance: DC electric field accelerates ion migration, increasing copper leaching rate by 15%.
Microwave radiation: selective heating of sulfide minerals, reducing reaction activation energy by 40%.
Process optimization key indicators
Metal recovery rate: copper ≥92%, nickel ≥88%, uranium ≥85
Energy consumption standard: power consumption per ton of ore <25kW-h, steam consumption <0.8t
Environmental compliance: heavy metal content of wastewater in line with GB25467 special emission limits
Economic threshold: processing ore grade copper ≥ 0.3%, gold ≥ 0.5g/t with profitability
Conclusion
The continuous innovation of leaching technology is reshaping the industrial pattern of modern non-ferrous
smelting. From high-pressure oxygen leaching to biometallurgy, from large-scale heap leaching to precise
in-situ extraction, the process progress has always been centered on “high efficiency, cleanliness and low
carbon”. In the future, with the deep integration of intelligent control system and green chemical reagents,
the leaching process will break through the existing technical and economic boundaries, providing core
support for the sustainable development of mineral resources. Grasping the essence of leaching dynamics
and building customized process solutions has become a strategic choice for smelting enterprises to
improve quality and efficiency.