Beyond Granulation: The Mechanical Refiner for the Metal Fraction (<1mm)

From separation to extreme value recovery: discover how ultra-refinement technology transforms mixed metal fractions into a premium product, ensuring homogeneous sampling and maximum yield for foundries.

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The Evolution of “Dry Refining”

In printed circuit board (PCB) recycling, the primary goal is to liberate metals from fiberglass and plastic. Industry standards typically stop at particle sizes of 2–4 mm—ideal for density separation but not optimized for maximum economic valorization of the final output.

Stokkermill engineering has developed the Mechanical Refiner, a unit specifically designed to process the clean metal fraction coming out of density tables. Although this material is copper-dominant, it is actually a polymetallic mix containing aluminum, tin, and trace (ppm) precious metals.

Our technology reduces this mix to sub-millimeter size (<1 mm / <1000 microns) without generating volatile dust. This micro-densification process represents a decisive strategic advantage.

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Why Go Below One Millimeter? 3 Strategic Advantages

Using the Mechanical Refiner addresses the precise needs of metal refiners and traders. Reducing the metal fraction size provides immediate benefits:

1. Homogeneity and Accurate Sampling
The metal fraction from PCBs is heterogeneous by nature. With coarse particles (4–5 mm), sampling accurately is statistically difficult—there’s a high risk of undetected ppm levels of precious metals in the dominant copper mass.
The Mechanical Refiner turns the mix into a homogeneous “metal sand”, ensuring that every analyzed sample accurately reflects the batch composition. This eliminates errors, giving foundries confidence and sellers fair compensation for every metal present.

2. Immediate Chemical Reactivity
In final refining plants, processing time is cost.
<1mm material exposes a vastly larger contact surface than coarse granules, allowing chemical agents or thermal processes to act on the metal instantly. This dramatically reduces dissolution time and energy consumption.

3. Premium Product
Delivering an ultra-fine metal fraction, completely free of inert contaminants (already removed upstream by Impact Mills), results in a high-efficiency semi-finished product.
Foundries receive a ready-to-use material, which allows for better commercial terms (lower treatment charges) since no additional mechanical preparation is needed.

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Conclusion: The Missing Link

The Stokkermill Mechanical Refiner is installed downstream of the density separation line as a high-end finishing module. It’s the technological answer for companies aiming to transform raw metal fractions into a premium, analyzable, and finance-ready product.

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