In the electrolysis workshop of the salt lake in the ChaiDaMu Basin of Qinghai, lithium ions are
shuttled between special diaphragms; and gold nanoparticles are precipitated from circuit boards
on the electronic waste treatment line in the town of Guiyu, Guangdong Province. These seemingly
magical scenes are actually industrial wonders created by contemporary non-ferrous metal
extraction technology.
The thousand-year evolution of pyrometallurgy
The flames in the blast furnace are still continuing the ancient wisdom. Copper concentrate and quartz
flux at a high temperature of 1250 ℃ stratification, ice copper and slag density difference to achieve
natural separation. Modern flash smelting technology speeds up the process a hundredfold - copper
concentrate particles oxidize in 0.2 seconds in the reactor tower, and thermal efficiency jumps from
35% to 65%.
Aluminum electrolyzers shine with the cold light of industrial civilization. In the cryolite molten salt,
alumina dissociates at 960℃, and the liquid aluminum precipitated from the cathode reaches 99.7%
purity. The hard constraint of 13,000 degrees of power consumption per ton of aluminum has given
birth to the technology of shaped cathode tank, and the current efficiency has been raised from 88%
to 96%, which is equivalent to saving half a month's power generation of the Three Gorges Power
Station every year.
Plasma melting opens a new era. 30kW arc instantly vaporizes electronic scrap, and metal vapor is
precisely graded in the condensation system. The separation efficiency of this technology for
complex alloys reaches 99%, and when dealing with circuit boards containing precious metals,
the recovery rate of gold and silver is 40% higher than that of the traditional incineration method.
The molecular game of hydrometallurgy
Chemical magic on the heap leach field is being staged. Low-grade copper ore slowly dissolves in sulfuric
acid solution, and the extractant molecules are like intelligent trappers, accurately capturing copper ions
from the blue leaching solution. A copper mine adopts biological heap leaching technology, utilizing
Thiobacillus ferrooxidans to shorten the leaching cycle from 180 days to 60 days.
The microscopic war inside the high-pressure reactor is thrilling. Nickel laterite ore reacts with concentrated
sulfuric acid at 240℃ and 4MPa, and the nickel and cobalt leaching rate breaks through 95%. This high-pressure
acid leaching technology (HPAL) reduces the energy consumption of traditional smelting by 60%, and
reduces carbon emissions by 8 tons per ton of nickel.
Ion exchange resin builds up the Great Wall of precious metals. The gold-containing tailings flow through
an adsorption column equipped with D201 resin, and the gold chlorate complex is selectively captured.
When the gold is eluted by the thiourea solution in the desorbent, the adsorption capacity of the resin still
maintains 98% of the initial value, realizing 2,000 times of recycling.
The technological revolution of physical sorting
Eddy current sorting machine plays the metal symphony. 3000 rpm magnetic rollers produce alternating magnetic
field, the aluminum sheet in the Lorentz force effect of the ejection of 3 meters, and the complete separation of
plastic debris. This dry sorting technology has increased the recycling rate of aluminum scrap from 78% to 95%,
with a water saving rate of 100%.
X-ray transmission recognition creates a sorting miracle. Intelligent sensors resolve the atomic number of metal scrap
within 0.03 seconds, and pneumatic nozzles accurately separate brass from stainless steel. A recycling base introduces
dual-energy X-ray system, and the sorting accuracy is increased from 82% to 99.7% by manual labor.
Superconducting magnetic separation opens a new dimension in rare earth purification. Liquid helium-cooled
superconducting magnets generate a strong magnetic field of 5 Tesla, and rare earth particles in NdFeB waste are
accurately captured by the gradient magnetic field. This technology makes the rare earth recovery rate exceed
90%, and the energy consumption is only 1/5 of the traditional magnetic separation.
Nature Code of Biotechnology
Metallophilic flora work quietly in the depths of the mine. Thiobacillus ferrooxidans converts the sulfur element in
chalcopyrite into sulfuric acid, and copper ions are enriched in the solution. In a copper mine bioleaching workshop,
10,000 tons of ore need not be crushed, and the leaching rate is stable at over 85%.
Phytoremediation creates green miracle. The root system of centipede grass penetrates deep into lead-containing
soil, absorbing 300 kilograms of lead elements per hectare per year. The harvested plants are pyrolyzed at low
temperature, and the lead is recycled in the form of lead oxide, and the heavy metal content of the soil is reduced by 90%.
Enzymatic method disrupts electronic waste treatment. Customized protease cuts off the epoxy resin in circuit boards
and metal contacts come off intact. This bio-stripping technology increases the gold recovery rate to 99% and
completely eliminates dioxin emissions.
The Future of Recycling
End-of-life cars are being transformed into mobile mines. The crushing line breaks down the car body into 300mm
pieces, and the heavy media sorting system separates the aluminum, magnesium and copper mixture. A base adopts
laser-induced breakdown spectrometer (LIBS), which realizes metal identification 20 times per second, and the purity
of sorting reaches 99.9%.
Power batteries open a second life. Mechanical dismantling line precisely separates positive and negative pole pieces,
and lithium cobalt acid powder is reborn in the reduction furnace. Wet metallurgy workshop adopts selective
precipitation technology, nickel and cobalt and manganese recovery rate are over 98%, lithium elements are
recovered in the form of lithium carbonate.
Electronic waste is transformed into urban gold mine. The pyrolysis system decomposes plastics in an
oxygen-deficient environment, and precious metal particles are gathered in the electrostatic sorter. A treatment
plant introduces supercritical CO2 extraction technology to extract gold from waste chips with a purity of 99.99%.