The recycling of scrapped automobile control cables is an important link in the recycling of resources in the automotive aftermarket. It involves the efficient recycling of precious metals such as copper and aluminium, and also takes into account environmental compliance (such as avoiding heavy metal pollution and harmless treatment of plastics). Its recycling process must comply with strict regulatory standards (such as China's "Regulations on the Recycling and Disposal of Waste Electrical and Electronic Products" and the EU's WEEE Directive), and the copper-aluminum conductor separation technology is the core for achieving high-value utilization of resources. The following is an explanation from two aspects: the entire recycling process and the separation technology of copper and aluminum conductors.

I. Scrap automobile control cables recycling process

The recycling process should revolve around "compliant collection → safe disassembly → precise sorting → clean treatment → resource utilization". The core objective is to maximize the recovery rate of copper and aluminum conductors (≥95%), while ensuring the harmless disposal of insulating materials, impurities, etc.

1. Collection and pretreatment stage

• Compliant collection

• Source: Scrap car dismantling enterprises, vehicles replaced by 4S stores, vehicles eliminated from the used car market, etc. It is necessary to confirm the legality of the source (such as scrapping certificates, ownership documents).

• Storage: Store in accordance with the "Pollution Control Standards for Hazardous Waste Storage". Control cables should be isolated from other automotive waste (such as batteries and oil) to prevent cross-contamination. Open-air storage should be covered with dust-proof nets to prevent heavy metal loss caused by rainwater erosion.

• Preliminary classification:

• Classified by cable type: single-core/multi-core control cables, shielded cables, high-speed signal cables (such as CAN lines, Ethernet cables), etc. The conductor materials (pure copper, copper-clad aluminum, aluminum) and insulation layers (PVC, XLPE, TPE) of different types of cables vary greatly and need to be handled separately.

• Classified by pollution degree: no obvious pollution (only external oil stains), severe pollution (contact with oil/coolant). Cables with severe pollution need to be flushed with high-pressure water guns first (wastewater is treated in an oil separator and sedimentation tank to meet standards before being discharged).

2. Disassembly and rough sorting stage

• Manual/mechanical disassembly

Objective: To separate control cables from automotive wiring harness assemblies and remove accessories such as connectors, terminals, and clamps.

• Tools: Diagonal pliers (to cut the clamps), wire strippers (to remove the external insulation layer), hot air guns (to soften the adhesive and separate the wire harness from the vehicle body). Note: Connectors (such as CAN bus plugs) contain precious metals (gold and silver coatings), which need to be disassembled and recycled separately to avoid mixing in conductor waste.

• Rough sorting:

• Magnetic separation: Ferromagnetic impurities (such as steel wire armor and iron nails) in cables are removed through permanent magnetic rollers or magnetic separators, with a recovery rate of ≥99%.

• Manual picking: Remove non-target cables (such as high-voltage power cables, coaxial cables) to ensure that the types of cables processed subsequently are uniform.

3. Core stage of conductor separation

At this stage, the copper/aluminum conductor needs to be thoroughly separated from the insulation layer, shielding layer and impurities to produce a high-purity copper-aluminum mixture (purity ≥98%). For specific techniques, please refer to the following "Copper/Aluminum Conductor Separation Technology".

4. Post-processing and resource utilization stage

• Conductor purification:

If the copper-aluminum mixture after separation contains a small amount of impurities (such as plastic particles and metal oxides), the purity can be further increased to over 99.5% by flotation (taking advantage of the difference in hydrophobicity on the surfaces of copper and aluminum) or heavy medium separation (adjusting the density of the suspension), to meet the standard for recycled copper and aluminum raw materials (GB/T 38472-2019).

• Insulation material treatment:

• PVC insulation layer: After crushing, it is sent to the rotary kiln for incineration (temperature 850-1000℃, combined with incineration slag for brick-making), and the tail gas is treated by activated carbon adsorption + bag dust removal (dioxin emission ≤0.1ng TEQ/Nm³).

• XLPE/TPE insulation layer: It can be used as raw material for recycled plastics (after cleaning and impurity removal, granulation is required), or fuel oil can be recovered through pyrolysis technology (in compliance with hazardous waste treatment standards).

• Resource-based output

• High-purity copper-aluminum mixture: Sold to copper-aluminum smelters, through electrolysis or smelting to produce refined copper and aluminum alloy ingots;

• Precious metals (such as gold and silver in connectors) : Extracted by pyrometallurgy or hydrometallurgy, with a recovery rate of ≥95%.

5. Environmental Protection and Compliance Management

• Wastewater: The disassembly and flushing wastewater and the insulation layer cleaning wastewater are treated by "oil separator + coagulation sedimentation + activated carbon filtration", with COD≤50mg/L and heavy metal ions ≤0.1mg/L before being discharged.

• Waste gas: Dust (bag filter, efficiency ≥99%) and VOCs (RTO incineration treatment, removal rate ≥98%) generated from the crushing and incineration processes must be discharged up to standard.

• Record: Establish a recycling ledger to record the source of the cables, their weight, the output of copper and aluminum after separation, and the data on pollutant treatment, for verification by regulatory authorities.

Ii. Key Technologies for Separating Copper and Aluminum Conductors

The conductors of control cables are mainly pure copper (T2 red copper), pure aluminum (1060 aluminum), or copper-clad aluminum (CCA, with a copper layer thickness of 5-10%). The separation needs to be based on the differences in material density, magnetism, conductivity, and surface characteristics. Common techniques are as follows:

1. Physical separation technology (mainstream method, environmentally friendly and efficient

Mechanical crushing + screening

• Principle: The cable is crushed into 2-5mm particles by crushing equipment. The density difference between the conductor (8.9g/cm³ copper, 2.7g/cm³ aluminum) and the insulation layer (1.2-1.4g/cm³) is utilized, combined with a vibrating screen and an air flow separator for separation.

• Equipment: Double-shaft crusher (shearing crushing to prevent excessive crushing of conductors), air flow separator (utilizing the principle of aerodynamics, light plastics are carried away by the air flow and heavy metals fall).

• Applicable scenarios: Multi-core control cables (such as automotive CAN bus cables), after being crushed, copper and aluminum particles are separated from plastic fragments, with a purity of up to 95-97%.

(2) Magnetic separation (removal of ferromagnetic impurities)

• Principle: By using permanent magnets or electromagnets to adsorb magnetic impurities such as iron and nickel in the cable (such as steel wire armor, ferrite magnetic rings), it prevents them from being mixed into the copper and aluminum mixture.

• Equipment: Drum magnetic separator (with large processing capacity, suitable for coarse crushed materials), strong magnetic separator (for fine powder materials, magnetic field intensity ≥10000Gs).

• Effect: The removal rate of iron impurities is ≥99%, ensuring the stable operation of subsequent sorting equipment.

(3) Eddy current separation (separation of copper, aluminum and non-magnetic metals)

• Principle: High-frequency alternating magnetic fields generate eddy currents in non-magnetic metals (copper, aluminum), which in turn produce reverse magnetic fields, causing copper and aluminum particles to be repelled and ejected, separating them from denser insulating materials or non-metallic impurities.

• Equipment: Eddy current separator (adjustable rotor speed, frequency 50-400Hz), copper and aluminum ejection trajectories are different from those of plastic and ceramic, and are collected through the discharge port.

• Advantages: It can further purify the copper-aluminum mixture to a purity of 98-99% without damaging the physical form of the conductor.

(4) Electrical separation (for copper-clad aluminum conductors)

• Principle: After being crushed, copper-clad aluminum conductors form "copper shell + aluminum core" particles. When passing through a high-voltage electric field (10-20kV), the difference in conductivity between copper (with a resistivity of 1.7×10⁻⁸Ω·m) and aluminum (2.8×10⁻⁸Ω·m) leads to different rates of charge accumulation, achieving separation.

• Equipment: Drum-type electrostatic separator (grounded drum + high-voltage corona electrode), copper particles with positive charge are adsorbed, while aluminum particles with negative charge fall.

• Applicable scenarios: Copper-clad aluminum cables (such as some low-end automotive wiring harnesses), with copper purity ≥99% and aluminum purity ≥98% after separation.

(5) Color separation (Visual recognition assistance)

• Principle: A high-definition camera identifies the color differences of the crushed materials (copper appears purple-red and aluminum appears silver-white), and the air injection valve blows particles of different colors into different material troughs.

• Equipment: Intelligent color sorter (resolution ≥0.1mm², processing speed 5-10t/h), suitable for small-batch and high-purity copper and aluminum separation.

2. Chemical separation technology (for auxiliary or special scenarios)

• Acid leaching method: Dissolve aluminium (2Al+3H₂SO₄=Al₂(SO₄)₃+3H₂↑) in dilute sulfuric acid (10-20% concentration). Copper does not react. After filtration, copper slag is obtained. The filtrate is neutralized and precipitated to recover aluminium salts.

• Disadvantages: It generates a large amount of acidic wastewater (which needs to be neutralized to pH=6-9), the aluminum recovery rate is only 85-90%, the environmental protection cost is high, and it is only used for difficult-to-separate materials with highly mixed copper and aluminum.

• Electrolysis method: A crude copper-aluminum mixture is used as the anode. When an electric current is passed through the electrolyte, copper precipitates preferentially (purity ≥99.95%), and aluminum enters the anode slime.

• Disadvantages: High energy consumption (about 15,000 KWH of electricity per ton of aluminum), only suitable for the purification of high-purity copper.

3. Combined application of technologies

In actual production, the combined process of "crushing and screening + magnetic separation + eddy current separation" is often adopted:

1. Cable → Double-shaft crusher (2-5mm particles) → Vibrating screen (separating uncrushed materials > 10mm)

2. Under-screen materials → permanent magnetic separator (iron removal) → eddy current separator (copper and aluminum separation);

3. Copper-aluminum mixture → Electrical separation/color separation (for copper-clad aluminum) → High-purity copper and aluminum powder.

This combined cable has a copper recovery rate of ≥98% and an aluminum recovery rate of ≥97%, with a comprehensive energy consumption of ≤500kWh/t, meeting the requirements of environmental protection and economy.

Iii. Precautions

1. Material identification in advance: Before recycling, the material of the cable conductor (copper/aluminum/copper-clad aluminum) should be quickly detected by an XRF spectrometer to avoid a decrease in separation efficiency due to mixed processing.

2. Explosion-proof and fireproof: When breaking the PVC insulation layer, HCl gas may be released, and an acid mist absorption tower needs to be configured. When separating aluminium powder, explosion-proof measures are required (the explosion limit of aluminium powder is 37-50g/m³). The equipment should be grounded and equipped with a dust concentration monitor.

3. Recycling standards: The separated copper and aluminum must comply with "Recycled Copper Raw Materials" (GB/T 38471-2019) and "Recycled Casting Aluminum Alloy Raw Materials" (GB/T 38472-2019), and the impurity content (such as lead ≤0.5%, tin ≤0.1%) must meet the standards before entering the smelting process.

Summary

The recycling of scrapped automobile control cables should be based on the premise of "compliance", and the high value of copper and aluminum resources should be achieved through the process of "disassembly - sorting - separation". Physical separation technologies (such as crushing and screening, magnetic separation, and eddy current separation) have become mainstream due to their environmental friendliness and high efficiency, while chemical technologies only serve as an auxiliary. In the future, with the popularization of intelligent sorting equipment (such as AI visual color sorting and robot disassembly), the recycling efficiency and purity will be further enhanced, promoting the development of the automotive aftermarket towards "zero waste and full circulation".