Magnetic separation in wood recycling for biomass production
Wood recycling is a key element in the development of biomass-based district heating systems, increasingly widespread for sustainable energy production.
To ensure efficiency, operational continuity, and fuel quality, wood material must meet precise technical specifications, particularly in terms of particle size and absence of metallic contaminants.
This case study demonstrates how Gauss Magneti’s magnetic separation technologies effectively support the recycled wood treatment process, ensuring its suitability for use in energy production plants.
The initial challenge: contamination and stringent specifications in wood recycling
The project developed with Hubert Etter is part of the district heating network built by Gruyère Energie SA (GESA) in the Bulle region (Switzerland), which extends over approximately 170 km and serves both residential and industrial users.
The system uses recycled wood as biomass, largely sourced from demolitions. Approximately 90% of the incoming material consists of pallets, beams, and panels, with a high level of contamination.
To properly feed the furnace, the material must meet precise requirements:
• particle size between 0 and 100 mm;
• fine fraction content below 7%;
• complete removal of ferrous and non-ferrous metals.
The presence of metallic contaminants poses a risk to plant reliability and the quality of the biomass produced.
The solution designed by Gauss: line integration with magnetic separation
To meet these specifications, a treatment line was developed combining several technologies, integrated to work continuously on heterogeneous material:
• slow-speed dual-shaft shredder (Komptech CRAMBO, full electric);
• star screen for particle size separation, with recirculation of oversized material;
• Gauss Magneti separation system for complete removal of ferrous and non-ferrous contaminants.
Within the process, magnetic separation plays a central role: it removes metals present in the shredded wood, ensuring the material complies with the required specifications.
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The result achieved by Hubert Etter: compliant biomass and metal recovery
After the shredding, screening, and magnetic separation stages, the resulting material meets the required standard (P100), with:
• controlled particle size (0–100 mm);
• fine fraction content within limits;
• absence of ferrous and non-ferrous contaminants.
The recycled wood can thus be safely used as fuel for the district heating system. At the same time, the separated metals are recovered and reintroduced into the recycling chain, helping to improve overall process efficiency.
Project summary: biomass quality and process reliability
In wood recycling for energy production, material quality does not depend on a single machine, but on the balance between the different stages of the process.
Particle size, fine fraction content, and metal removal are closely interconnected parameters that require an engineering approach consistent with real working conditions.
In this context, magnetic separation is not an accessory element, but a technical component that directly contributes to the stability and reliability of the plant.
This is the type of application where Gauss Magneti steps in: analyzing the process as a whole and designing separation solutions capable of delivering consistent results, even on heterogeneous and highly variable materials.
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