Steel Recovery — Upgrading Levels and Buyers
Three levels of steel cleaning from tyre pyrolysis — mechanical (90–95% purity), thermal kiln (97%), and chemical HCl treatment (98–99%) — with the upgrading process and target buyers at each purity tier.
| Cleaning Method | Process | Purity | Target Buyers |
|---|---|---|---|
| Mechanical Cleaning | Tumbling, brushing, vibratory, air-blowing | 90–95% | Local scrap yards, secondary steel producers, foundries |
| Thermal Cleaning | Controlled heating in rotary kiln/furnace | ~97% | Steel re-rolling mills, large-scale producers, automotive foundries |
| Chemical Cleaning | Treatment with HCl to remove oxides, zinc, ash | 98–99% | Primary steel producers, specialty foundries, alloy steel units |
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How to read this table
- Each row is one cleaning method; columns show the cleaning process, achieved steel purity, and target buyers at that purity level.
- Methods are listed in ascending purity and cost order — operators typically start with mechanical cleaning and upgrade only if market access at higher purity justifies the investment.
- Chemical cleaning requires acid handling infrastructure — this is not a drop-in upgrade but a separate process investment requiring additional regulatory compliance for acid storage and effluent treatment.
About this table
Steel wire recovered from tyre pyrolysis — from bead wires and belt reinforcement that has been de-vulcanised and oxidised by the pyrolysis heat — is the third revenue stream alongside oil and carbon black. But the selling price per tonne and the buyer pool available for the steel depend significantly on how thoroughly the char and rubber residue are cleaned from the wire surface. This three-tier table maps cleaning level to purity, process, and buyer type.
The baseline Mechanical Cleaning (90–95% purity) uses tumbling, brushing, vibratory screens, and air blowing to remove loose char and ash from the steel wire surface. This is the simplest and lowest-cost cleaning approach — suitable for most standard operations. At 90–95% purity, the steel is suitable for local scrap yards, secondary steel producers, and small foundries that process mixed scrap. This is the most common route for Indian tyre pyrolysis operators — it adds no capital for additional cleaning equipment and produces steel within the acceptance range for local scrap buyers.
Thermal Cleaning (approximately 97% purity) passes the steel through a controlled-atmosphere rotary kiln or furnace to burn off residual carbon and organic contamination. The result is a cleaner, oxide-free surface steel suitable for steel re-rolling mills, larger-scale secondary producers, and automotive foundries that specify a higher minimum steel content. Thermal cleaning requires a separate furnace, adding capital and operating cost — but the price premium per tonne of cleaner steel may justify the investment at larger volumes. Chemical Cleaning (98–99% purity) treats the steel with hydrochloric acid (HCl) to dissolve iron oxides, zinc oxide, and residual ash — producing the highest purity steel suitable for primary steel producers, specialty foundries, and alloy steel units. Chemical cleaning requires acid-handling infrastructure (tanks, pumps, ventilation, and effluent treatment for the spent acid) — a significantly more complex addition than mechanical or thermal cleaning. The resulting steel at 98–99% purity commands a premium price, but the investment is typically only justified at large volumes or where a specific premium buyer has been contracted.
Key insights
- Mechanical cleaning at 90–95% purity is sufficient for local scrap yard sale — the market for mechanically cleaned tyre steel is well-established and does not require additional investment.
- Thermal cleaning to 97% opens steel re-rolling mill and automotive foundry buyers — a price premium over local scrap may justify the additional capital investment at mid and high throughput volumes.
- Chemical cleaning to 98–99% requires acid handling infrastructure and effluent treatment — this is a significant additional compliance and capital burden that is only commercially justified by contracts with primary steel buyers at premium prices.
- The steel revenue stream from pyrolysis is secondary to oil and carbon black but non-trivial — at 20–25% steel content in tyre feedstock, a 10 TPD plant recovers 2–2.5 tonnes of steel per day, which at scrap prices adds meaningful secondary revenue.
Methodology & sources
Steel purity levels and cleaning methods described are based on standard tyre pyrolysis industry practice as of 2024. Actual purity achievable depends on feedstock (car vs truck tyres have different steel compositions), reactor conditions, and cleaning equipment quality. Buyer specifications for steel purity vary and must be confirmed with specific buyers in the target market before designing the steel cleaning stage. Acid handling for chemical cleaning requires compliance with Hazardous Waste (Management) Rules and SPCB consent for acid storage.
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