Preparing mixed connector scrap for maximum ALS2 yield
Mixed connector scrap can contain a concentrated value of gold, silver, palladium and copper, yet its composition is rarely uniform. A single batch may include plated pins, copper alloys, ferrous shells, tin-rich contacts, engineering plastics, dust and residues from previous processing. This variability directly affects how efficiently a recovery plant can separate valuable metals from unwanted material.
For an ALS2-based process, preparation is therefore a production step rather than a preliminary housekeeping task. Careful sorting, depollution, size control and feed monitoring help create the physical conditions required for stable acidless separation. The objective is to expose precious-metal-bearing surfaces without turning the feed into an unmanageable mixture of fines and contaminants.
Why feed preparation controls recovery
The precious-metal content of connectors is usually concentrated in thin surface coatings or selected contact areas. Gold plating may be present over nickel, copper or a copper alloy, while other components can contain tin, silver or palladium. The bulk mass, however, is often made up of base metals and non-metallic materials with very different densities and mechanical properties.
If these fractions remain attached, valuable surfaces may stay locked inside composite pieces. Oversized housings can carry plated contacts through a separation stage without adequate liberation, while excessive shredding can produce plastics and metal dust that are difficult to classify. Both conditions can lower yield, increase recirculation and make downstream concentrate quality less predictable.
Preparation also protects equipment. Steel clips, screws and oversized ceramic or plastic parts can cause irregular loading, block screens or accelerate wear. Removing these materials before controlled size reduction gives the ALS2 line a more consistent feed and helps operators maintain stable process conditions.
Start with a representative material audit
Before processing a large lot, establish what the connector scrap actually contains. Record the source, connector type, estimated plating, visible contamination and approximate proportions of ferrous, non-ferrous and polymeric material. Photographs and batch codes are useful when several suppliers or dismantling lines contribute to the same stockpile.
A practical audit should include representative sampling rather than a handful of visually attractive pieces. Mixed e-waste can segregate during transport and storage, with heavier metal pieces settling below lighter plastic-rich fractions. Samples should therefore be taken from different points in a batch and combined according to a documented sampling procedure.
Laboratory analysis can support visual inspection. X-ray fluorescence may help screen for copper, nickel, tin, zinc and precious-metal coatings, while more detailed assays can establish gold, silver or palladium content. The results should guide sorting and blending decisions, but they should not replace physical inspection: a high assay does not reveal whether the metal is accessible or still attached to a plastic carrier.
Remove contaminants before size reduction
Depollution should take place before shredding whenever practical. Remove batteries, capacitors, cables, large steel brackets, rubber seals, loose dust and components containing hazardous substances according to applicable waste-handling requirements. Connectors that are oily, wet or heavily soiled should be isolated for controlled cleaning rather than introduced directly into the main feed.
Plastic is especially important to manage. Connector bodies, insulation and engineering polymers add mass without contributing to metal recovery, and some plastics can become stringy or electrostatically difficult during mechanical processing. Removing obvious housings and bulky polymer pieces improves the metal concentration of the feed and reduces the volume handled by the separation plant.
Do not mix contaminated material with clean, high-grade connector scrap merely to simplify logistics. Oils, chlorinated residues, lead-bearing parts and excessive dust can affect workplace safety, emissions control and the quality of recovered fractions. A clean feed supports the acidless character of ALS2 processing by reducing the need for corrective handling and auxiliary treatment.
Separate by construction and metal content
Sorting mixed connectors into families often produces a larger improvement than simply increasing shredding intensity. Useful categories may include gold-plated edge connectors, telecommunications contacts, automotive connectors, computer backplane connectors, relay contacts and low-grade tin-plated plugs. Each group can have a different ratio of plating to substrate and a different liberation response.
Ferrous separation should be performed early when steel components are present. Magnetic removal can take out steel shells, springs and clips before they are reduced into small particles. Non-ferrous metals such as copper, brass and nickel alloys should be kept available for the appropriate separation route, while ceramic-heavy or plastic-heavy items may need a separate treatment stream.
Where complete sorting is impractical, controlled blending is preferable to random mixing. Combine batches with known characteristics to keep precious-metal concentration, moisture and particle-size distribution within a manageable range. Stable feed chemistry and physical composition make it easier to interpret ALS2 performance and identify changes caused by the material rather than by the equipment.
| Preparation factor | Risk when poorly controlled | Preferred practice | Benefit for ALS2 operation |
|---|---|---|---|
| Connector type | Variable plating and substrate content | Sort by product family and origin | More predictable precious-metal loading |
| Ferrous content | Equipment wear and contamination of non-ferrous output | Remove steel magnetically before fine processing | Cleaner non-ferrous feed |
| Plastic and rubber | Dilution, dust and unstable classification | Depollute and remove bulky polymers | Higher metal concentration |
| Particle size | Poor liberation or excessive fines | Use staged, adjustable size reduction | Better exposure and separation |
| Moisture and oil | Adhesion, plugging and inconsistent handling | Keep feed dry and isolate contaminated lots | More stable conveying and screening |
| Sampling | Misleading assay or batch decisions | Use multiple, documented increments | Better control of grade and yield |
Use staged size reduction for liberation
The aim of size reduction is to free plated contacts and metal-bearing particles, not to make every item as small as possible. A staged approach is usually more controllable: first break or cut large connector assemblies, then remove liberated plastics and steel, and only then apply finer reduction to the remaining metal-rich fraction.
Screening between stages can prevent already liberated material from being damaged further. Coarse particles can return for additional liberation, while correctly sized material moves forward. This reduces energy consumption and limits the generation of ultra-fine particles, which may carry precious metals but can also increase dust losses and complicate classification.
The correct target size depends on connector design, plating thickness, substrate alloy and the ALS2 plant configuration. Operators should determine it through controlled trials rather than applying a universal setting. Examine the product after each stage for intact plated pieces, flattened metal, polymer-metal composites and excessive fines. These observations provide a direct basis for adjusting cutter gaps, rotor speed and screen selection.
Control fines, moisture and storage conditions
Fine particles deserve specific attention because they can contain a disproportionate share of liberated plating and metal dust. At the same time, fines may become entrained in light fractions, adhere to plastic or accumulate in transfer points. Dust extraction, enclosed conveying and suitable screening help retain valuable material while protecting operators and equipment.
Moisture changes the flow characteristics of shredded connector scrap. Damp feed can agglomerate, stick to screens and behave differently from dry material during classification. Store prepared fractions under cover, use clean containers and monitor moisture when material has been washed, exposed to rain or transferred from a humid environment.
Avoid long, uncontrolled storage of finely prepared scrap. Vibration can cause density segregation, with heavy metal particles settling below lighter fragments. If a batch must be stored, use clearly identified lots, limit drop heights and remix according to the site’s sampling and blending procedure before processing. Traceability is essential when comparing recovery results across different feedstocks.
Define acceptance criteria for the ALS2 line
A clear feed specification turns preparation into a repeatable quality-control activity. It can include maximum particle size, acceptable fine fraction, moisture range, ferrous content, visible polymer percentage and restrictions on oils or hazardous components. The exact limits should be established with the ALS2 equipment supplier or plant operator through commissioning tests.
Feed inspection should continue during production. Weigh incoming and rejected fractions, record screen results and retain samples from each lot. Track the mass balance from prepared feed to recovered metal-rich products and residual fractions. If precious-metal losses rise, the cause may be incomplete liberation, excessive fines, poor sorting or an incorrect classification setting.
Yield should also be assessed alongside product quality. A high recovery percentage is less useful if the concentrate is diluted by unnecessary base metal or requires excessive reprocessing. The best operating point balances precious-metal recovery, concentrate grade, throughput, energy use and the handling of residual material within the compact recovery plant.
A practical preparation routine
- Identify each incoming lot by source, connector family, date and estimated composition.
- Remove batteries, bulky plastics, ferrous hardware, oils, dust and other unsuitable contaminants.
- Separate high-grade plated contacts from low-grade or heavily polymer-bound connector scrap.
- Apply staged size reduction with screening between stages, checking liberation and fine generation.
- Keep prepared fractions dry, traceable and consistent before feeding them to the ALS2 process.
The value of connector scrap is determined long before the final recovered fraction is weighed. A disciplined preparation routine gives the acidless ALS2 technology a cleaner, more uniform and more accessible feed, helping the process recover precious metals from electronic waste without relying on conventional acid-based refining.
Ikoi S.p.A.’s ALS2 project addresses the need for practical, cleaner precious-metal recovery in WEEE and electronic scrap applications. To evaluate mixed connector material, define a representative feed specification and arrange a technical assessment of sorting, liberation and plant conditions for your recycling stream.