As the base metal of modern industry, copper refining
technology has evolved over thousands of years. From
early pyrometallurgy to modern hydrometallurgy, the
copper extraction process has been continuously innovated.
The current mainstream industrialized copper extraction
method can be divided into pyrometallurgy, hydrometallurgy
and electrolytic refining three systems, different methods
according to the type of ore, grade and environmental
protection requirements of the combination of applications,
the formation of a complete copper metal production chain.
Pyrometallurgy: the core process of copper
sulfide ore extraction
Copper sulfide ore is crushed to 15-50mm particle size and then
entered into the flotation process. Adopting yellow drug type
trapping agent and turpentine oil foaming agent, in the alkaline
environment of pH8.5-9.5, the copper minerals selectively attach
to the air bubbles, and produce concentrates containing 20%-30%
copper. The advanced flotation unit is equipped with online X-ray
analyzer to adjust the additive amount of chemicals in real time,
and the recovery rate can reach 90%-95%.
The smelting process is carried out in an oxygen-enriched environment
at 1250-1300℃. Concentrate and quartz flux are put into the flash
smelting furnace in the ratio of 3:1, and the copper matte grade is
increased to 60%-65%. Intelligent control system precisely regulates
the ratio of oxygen and material, so that the sulfur utilization rate
reaches more than 98% and the concentration of flue gas SO₂ is
stable at 13%-15%, which provides high-quality gas source for the
subsequent acid production.
Converter blowing converts copper matte into crude copper. By
alternately adding quartz flux and blowing oxygen-enriched air
(containing 28%-32% oxygen), the iron and sulfur removal is completed
in two stages: the first stage produces white copper matte (containing
75%-78% copper), and the second stage obtains crude copper
containing 98.5%-99.5% copper. The whole process adopts laser
temperature measurement and gas analysis interlocking control,
and the crude copper direct yield is increased to 97%.
Wet Metallurgy: Preferred Solution for
Oxidized Ore Treatment
Heap leaching technology treats oxide ore containing 0.2%-1.5%
copper. The ore is crushed to -10mm and then piled up in layers,
with the height of each layer being 1.2-1.5m, and sprayed with
diluted sulfuric acid solution of pH1.8-2.2. Intelligent spraying
system dynamically adjusts the flow rate according to the copper
concentration of leaching solution (2-4g/L), with a leaching
cycle of 45-60 days and a copper leaching rate of 75%-85%.
Agitation leaching is suitable for high-grade oxidized ore. In Φ10m×12m
mechanical agitation tank, the slurry concentration is maintained at
35%-40%, the temperature is 50-60℃, and 0.05%-0.1% surfactant is
added to improve the leaching efficiency. Online potential monitor
(ORP 400-450mV) automatically controls the amount of oxidizer
added, and the leaching operation is completed in 6-8 hours,
with a copper recovery rate of more than 92%.
Solvent extraction system realizes selective enrichment of copper ions.
The three-stage counter-current extraction device adopts LIX984N
extractant, and the copper loading reaches 5-7g/L compared with
O/A=1:3. The membrane separation technology reduces the loss
of organic phase entrainment to less than 50ppm, and the
counter-extractant adopts 180-200g/L sulphuric acid, and the
copper concentration of the output electrolytic solution is 45-50g/L.
Electrolytic refining: the key link of high
purity copper production
The anode plate casting adopts quantitative casting ladle and
vertical continuous casting unit, and the temperature of copper
liquid is controlled at 1150-1170℃. The casting molds are sprayed
with carbon powder isolating agent, and the output is anode
plates with specifications of 1000×1200×45mm, weight of
380-420kg/block, and qualification rate of 99.8%.
The electrolysis tank group is equipped with intelligent
management system. Polymer concrete tank size 4×1.2×1.5m,
same pole distance 90-100mm, current density 280-320A/m²
Electrolyte contains Cu²+ 45±2g/L, H₂SO₄ 180±5g/L, temperature
58-62℃ cycle, titanium tube heat exchanger to maintain
temperature control accuracy ±0.5℃.
The quality of cathode copper reaches GB/T 467-2010 standard.
316L stainless steel mother plate surface roughness Ra≤0.8μm,
7 days after the electrolysis cycle stripped 1.5-2.0mm thick
cathode copper, purity 99.99%, bright surface without copper
powder. The automatic washing unit adopts 80℃ pure water
rinsing, and the water consumption per ton of copper is
reduced to 0.3m³.
Environmental protection and comprehensive
utilization of resources
The flue gas control system realizes ultra-low emission. The conversion
rate of double-rotation and double-absorption acid-making device is
99.95%, and the concentration of SO₂ in the tail gas is ≤50mg/Nm³.
Electrodusting + activated coke adsorption combination process,
particulate emissions <10mg/Nm³. Waste heat boiler recovers
medium-pressure steam, and power generation meets 30% of
production power consumption.
Wastewater recycling rate exceeds 95%. Membrane treatment system
integrates ultrafiltration + reverse osmosis technology, and the reuse
water quality reaches GB/T 19923 standard. Neutralization slag
contains less than 0.1% copper after press filtration, which is
comprehensively utilized as raw material for building materials.
Electrolysis waste liquid produces copper sulfate crystals through
vacuum evaporation, with a reuse rate of 98%.
Intelligent transformation improves production efficiency. The digital
twin system simulates the current distribution of electrolyzer in real
time, and the prediction accuracy reaches 97%. The machine vision
detects the quality of cathode deposition and automatically adjusts
the pole distance with an accuracy of ±1mm. the energy management
system optimizes the distribution of electricity, and the comprehensive
energy consumption of tons of copper is reduced to 1.2 tons of standard coal.
Modern copper smelting technology has formed a closed-loop system of
resources - products - renewable resources. The transformation process
from ore to 99.99% high-purity copper cathode comprehensively
recovers gold, silver, platinum and other rare precious metals, and
the utilization rate of sulfur element is close to 100%. Driven by the
dual-carbon strategy, green technologies such as oxygen-enriched
smelting and bioleaching are continuously upgraded to promote
the deep transformation of the copper smelting industry in the
direction of high efficiency and cleanliness. This whole-process
technology system not only guarantees the stable supply of
copper resources, but also sets a benchmark for the sustainable
development of the non-ferrous metal industry.