Keywords: metal separation, smelting process, recovery technology, environmental protection treatment, resource reuse
In the non-ferrous metal smelting industry, metal separation technology is the core link to improve resource utilization,
reduce energy consumption and reduce environmental pollution. Whether it is ore refining, waste recycling or alloy
processing, how to accurately and efficiently separate different metal components is always the focus of industry
practitioners. In this paper, we will start from the physical, chemical and biological separation technology in three
major directions, analyze the current mainstream metal separation methods and their application value.
Physical separation technology: from basic to high-precision breakthroughs
Physical separation relies on the difference in physical properties of metals (such as density, magnetism, electrical
conductivity, melting point, etc.) to achieve sorting, with low energy consumption, the advantages of simple
operation, especially for the primary processing stage.
Magnetic Separation and Eddy Current Separation
Magnetic separation separates ferromagnetic materials (e.g. iron, cobalt, nickel) from other metals through the
difference in the magnetic properties of the metals. Eddy current separation, on the other hand, is used for
non-ferrous metals (e.g. aluminum, copper), and uses the repulsive force generated by an alternating magnetic field
to separate metals with different electrical conductivity. This type of technology is widely used in the field of scrap
metal recycling, for example, to separate copper wires and aluminum housings from e-waste.
Re-election and Flotation Processes
Re-election utilizes the difference in density of metals to separate coarse-grained metals from impurities by means
of gravity separation equipment (e.g., jig, shaker). Flotation, on the other hand, extracts the target metal by
adjusting the action of chemicals and bubbles so that the target metal is attached to the foam layer. Flotation
technology is particularly critical in the processing of copper, lead and zinc ores, and can significantly improve
concentrate grades.
Laser and X-ray sorting
With advances in sensor technology, laser-induced breakdown spectroscopy (LIBS) and X-ray fluorescence
analysis (XRF) have become new options for high-precision separation. These technologies can identify metal
components in real time and are suitable for screening complex alloys or trace metals, such as separating
cobalt, lithium and other key elements from waste batteries.
Chemical Separation Technology: Deep Purification and Resource Recovery
Chemical separation through the chemical reaction characteristics of the metal (such as redox potential, solubility,
complexity) to achieve separation of components, suitable for high-purity metal extraction and complex ore processing.
Hydrometallurgy: Selective Dissolution and Precipitation
Wet metallurgy utilizes acid, alkali or complexing agent to dissolve the target metal, and then completes the separation
through solvent extraction, ion exchange or electrolytic deposition. For example, when extracting high-purity copper
from copper-containing waste liquid, sulfuric acid leaching - electrolytic refining process can be used, and the
recovery rate can reach more than 95%.
Pyrometallurgy: Synergistic effect of smelting and distillation
Pyrometallurgy forms alloys or slag layering of metals through high-temperature melting, and then combines with
distillation technology to separate low-boiling-point metals (e.g., zinc, mercury). This method is effective when
dealing with polymetallic co-generated ores, for example, by controlling the melting temperature gradient to
achieve stepwise recovery of lead, silver and zinc.
Electrochemical separation: the “gold standard” for targeted purification
Electrolytic refining is a typical application of chemical separation. By adjusting the current density and electrolyte
composition, metal ions are deposited directionally at the cathode. This technology is widely used in the deep
purification of base metals such as copper and aluminum, and is also a key step in the production of high-purity
precious metals (such as gold and platinum).
Biological separation technology: the future direction of green smelting
With the tightening of environmental requirements, biometallurgical technology has gradually become the industry's
new favorite. It utilizes the metabolic activities of microorganisms to decompose metal compounds and realize
separation under mild conditions.
Bioleaching: the “chemical decomposition power” of microorganisms
Certain thiobacilli can convert metals into soluble salts by oxidizing sulfides, which is suitable for low-grade ores or
tailings treatment. For example, bioleaching of copper ores can reduce acid and energy consumption while
reducing sulfur dioxide emissions.
Bio-adsorption and enrichment
Utilizing the adsorption properties of microbial cell walls to enrich precious metals (e.g., gold, silver) from wastewater
or waste streams. This method is low cost and environmentally friendly, and has made breakthroughs in the field
of e-waste recycling.
Biofilm Separation Technology
By constructing biomimetic membrane materials to simulate the selective adsorption mechanism of microorganisms,
high efficiency filtration of metal ions is realized. This technology performs well in the treatment of heavy
metal-containing wastewater, with both separation and purification functions.
Environmental protection and resource reuse: the added value of separation
technology
Metal separation is not only the core of the production process, but also the key to environmental protection. For example:
Waste Resourcing: By separating the residual metals (such as iron and manganese) in the tailings, industrial waste can be
transformed into secondary resources;
Waste gas treatment: utilizing adsorption materials to separate harmful metals such as lead and cadmium in smelting flue
gas to reduce air pollution;
Wastewater purification: combining chemical precipitation and biological adsorption technology to recover nickel, cobalt
and other precious metals in wastewater, realizing the goal of zero discharge.
Technology Trends and Industry Challenges
The current metal separation technology is developing in the direction of intelligence and integration:
AI-assisted separation system: optimize pharmaceutical ratios and process parameters through machine learning to
improve separation efficiency;
Compound process linkage: combining physical, chemical and biological methods to form a “gradient separation”, such
as first flotation enrichment and then electrolytic refining;
Nanomaterials application: developing highly selective nanosorbents to accurately capture rare metals (e.g. indium, gallium).
However, the industry still faces challenges: high separation costs for complex alloys, low trace metal recovery rates,
and increasingly stringent environmental regulations. In the future, how to balance technical feasibility and economics
will be the key to competitiveness.
Conclusion
From traditional magnetic separation to cutting-edge biometallurgy, the progress of metal separation technology directly
determines the efficiency and sustainability of the non-ferrous smelting industry. Whether it is to improve ore utilization,
reduce carbon emissions, or promote the circular economy, the scientific selection of separation solutions can create
significant value for enterprises. With the breakthroughs in material science and automation technology, metal separation
will continue to evolve in the direction of higher precision and lower energy consumption, providing strong support for
the industry's green development.