In the steel bar production and wire manufacturing sectors – such as the drawing and processing of low-, medium- and high-carbon wire rod – deformation and mechanical flaking operations continuously generate iron oxide flake waste. For some companies operating in these sectors, based in the Emilia-Romagna and Lombardy regions (Italy), managing iron oxide flakes as waste could entail a disposal cost of up to €15,000 per year, calculated on the basis of a disposal cost of €100 per tonne and a constant volume of 150 tonnes per year.
Thanks to the Industrial Symbiosis partnership with Sfridoo, the iron oxide flakes have been reclassified as a by-product under Article 184-bis of Legislative Decree 152/2006 and are now used in the production of oxides for the ceramics and glass industries: this change in regulatory classification has transformed a disposal cost into a revenue of €1 per tonne (Sfridoo Case Study CS44).
| CS44 Sfridoo | Pre | Post | Notes and operational details |
|---|---|---|---|
| Company profile | |||
| Sector | Province/REGION | Notes | |
| Producer | Steel bar production; wire production | Emilia-Romagna and Lombardy (Italy) | Aggregated data across multiple companies |
| User | Production of oxides for the ceramics and glass industry | Reggio Emilia (Italy) | |
| Pre / post comparison | |||
| Classification | Waste | By-product | Prepared: technical report, by-product qualification form, supply agreement, declaration of conformity, management model |
| Destination | Recovery | Production of iron oxides | |
| Quantity | 150 tons/year | 150 tons/year | Illustrative quantity used as calculation basis for the valorization |
| Storage | Big Bag | Big Bag | |
| Costs | −€100/ton | +€1/ton | From a disposal cost to a recognized positive value |
| Technological intervention | □ Yes ☑ No |
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| Characteristics |
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The management of flake iron oxides as waste
The processes of mechanical deformation and scaling of wire rod and steel bars continuously and predictably generate iron oxide scale. For companies involved in the production of steel bars and wire, this results in a constant flow of material treated as waste: 150 tonnes per year can incur disposal costs of €100 per tonne, amounting to an annual expenditure of €15,000. Furthermore, the additional administrative burdens imposed by waste legislation must be taken into account.
Iron oxide flakes are not a residue of variable composition: they are generated by a well-defined process, have consistent analytical characteristics (iron oxides ≥ 90% w/w) and, therefore, the potential to be identified as suitable for other supply chains. Companies that have turned to Sfridoo were managing these residues with all the obligations associated with waste.
What are iron oxide flakes and how are they produced in steelmaking?
Flake-like iron oxides, commonly known as rolling scale, are a mixture of oxides that forms during the hot-working of steel products. The interaction between steel and oxygen in the air generates this mixture, which serves precisely to protect the ferrous material.
If this scale were to remain intact, adhering firmly to the workpiece, it would form a protective layer over the steel. However, due to the exposure of workpieces to the elements during transport and storage, and to the stresses of routine workshop activities, this layer rarely remains intact. Moisture penetrates the cracks and reacts with the oxide layer closest to the steel’s surface, forming ferrous and ferric hydroxides which, due to their expansion, cause the layer to flake off. For this reason, the scale must be removed before the subsequent stages of manufacturing the metal product.
The processes of uncoiling and scaling raw steel wire rod thus produce a grey-black residue in the form of flakes, with an average particle size of approximately 30 mm.
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Find out moreThe journey of flaked iron oxides to becoming a by-product with Sfridoo
Following Sfridoo’s intervention, the companies involved now have a comprehensive set of documents enabling them to manage iron oxide flakes as a by-product, including a technical report, a by-product data sheet, a supply contract with the purchaser, a declaration of conformity and a management template.
The analysis confirmed that the flakes generated by the production processes for steel bars and wire met the requirements of Article 184-bis of Legislative Decree 152/2006, confirming their classification as a by-product.
The iron oxide scale is no longer sent for recovery as waste, but is now utilised as a raw material for the production of oxides for the ceramics and glass industries, under a supply contract that regulates its transfer and guarantees its traceability.
Benefits for steel bars and wire producers
The first direct effect relates to material handling costs; indeed, companies that previously paid €100 per tonne to dispose of iron oxide flakes as waste now eliminate this cost entirely, achieving a 100 per cent saving on disposal costs. Furthermore, they are paid €1 per tonne for the same material, now a by-product destined for destined as a by-product oxide for the ceramics and glass industries.
The total economic value generated – comprising savings and new revenue – is equivalent to 101 per cent of the original disposal cost (calculation basis: €101 per tonne of combined benefit against €100 per tonne of previous cost). Based on the reference flow of 150 tonnes per year mentioned at the outset, this translates into an economic benefit of approximately €15,150 per year (€15,000 in avoided costs + €150 in new revenue).
For companies certified to ISO 14001 or engaged in preparing a sustainability report, the reclassification of iron oxide flakes as a by-product means improved environmental performance indicators and more robust content for ESG reporting. The residues are now, in fact, excluded from the annual waste accounts. At plant level, the traceability of the flow follows a more standardised process, from the generation of the flakes right through to their destination within the identified supply chain – either ceramics or glass – with clearer procedures for staff and a lower risk of non-compliance with documentation requirements.
Finally, channelling the by-product into the ceramics and glass supply chain places it within a value-added supply chain, which also has a positive impact on sustainability narratives vis-à-vis customers and business partners.
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