ALS2 treatment of electric arc furnace dust
Steelmakers across Australia manage a fine, troublesome by-product whenever scrap is melted in an electric arc furnace: zinc-rich, iron-bearing dust pulled from baghouses and gas-cleaning systems. The stream can also carry copper, lead and other metals, while precious-element content varies with the scrap feed. The treatment of metal-bearing dust from electric arc furnace operations with ALS2 is therefore worth assessing as a source of recovered material rather than a residue sent away.
ALS2 is Ikoi S.p.A.’s acidless separation approach, developed with support from the European Union’s Horizon 2020 research and innovation programme. Its original focus is precious-metals recovery from waste electrical and electronic equipment (WEEE), with safer, cleaner processing and compact recovery plants as central aims. Applying that approach to steel dust requires fresh trials because furnace feed, scale and residue rules differ. The ALS2 project background sets out the wider technology context.
Why furnace dust is a strategic liability
During steelmaking, zinc in scrap coatings oxidises and joins iron oxides, while other feed constituents concentrate in the fine fraction. The result is a low-bulk, high-surface-area dust that is difficult to handle and may require controlled disposal. Its composition is not fixed: changes in scrap sources, coated products and operating conditions alter zinc, lead, copper and alkali content. Any economic case must therefore rest on current site assays rather than generic EAF-dust data.
The key operating difference can be summarised before assessing the full flowsheet:
| Feature | Conventional acid-based refining | ALS2-enabled approach |
|---|---|---|
| Reagents | Strong mineral acids and neutralisation chemicals | Acidless separation with controlled process chemistry |
| Main risks | Corrosion, spills, acid storage and hazardous wastewater | Feed variability, reagent handling and separation performance |
| Plant form | Often extensive tank, evaporation and wastewater infrastructure | Potentially compact and modular, subject to pilot design |
| Residues | Can include substantial quantities of neutralised salts and slurries | Aims to reduce hazardous liquid waste, but solid residues still require testing and approval |
| Readiness | Established for many refining feeds | Broader WEEE development; EAF-dust use requires site validation |
This is not a promise that every dust stream will yield the same value. Zinc and iron volumes may drive the balance, while precious metals matter only when assays and recovery economics justify dedicated finishing steps. The comparison identifies design expectations rather than guaranteed outcomes; mass balance, product quality and legal waste classification remain decisive.
How ALS2 changes the separation route
ALS2 offers a route in which separation does not depend on a conventional acid-reagent train. For an EAF-dust project, that means evaluating a flowsheet around the actual dust matrix rather than treating it as a liquid leach feed by default. Logical stages include representative sampling, size and moisture control, selective metal release or separation, product finishing and residue management. The precise unit operations must be confirmed in pilot work.
The commercial attraction is not simply the word acidless. Fewer corrosive liquids can reduce handling risk, simplify plant layout and avoid some neutralisation-related streams, but separation still has to deliver saleable products at an acceptable cost. Zinc and iron-rich fractions may serve nearby steelmakers, while a copper or precious-metal stream can have value where grade and recovery justify further processing. Low-grade output should not be presented as a recovered metal.
Control is especially important because furnace dust is heterogeneous. Online pH, temperature and solids-density measurements may be joined by assay-based feed blending, with laser analysis or laboratory checks used to correct the recipe. ALS2 should therefore be assessed as a managed separation plant integrated with dust collection, not as an isolated laboratory reaction that can accept any residue.
Preparing furnace dust for ALS2
A credible test programme starts with a sampling plan covering normal production, dusty campaigns and changes in scrap supply. Composite samples should be split for total metal analysis, mineralogy, particle size, moisture and leachability. This matters in Australia because transported and blended scrap can arrive from multiple sources, and because a single grab sample can exaggerate or hide the value of a rare metal.
Before separation, operators should consider agglomeration, de-dusting and moisture reduction while checking whether dust contains hazardous lead compounds or other substances that make handling tightly controlled. Fine particles require enclosed transfer points, local extraction ventilation and suitable respiratory protection. If the material is hazardous under the applicable Australian waste law, its transport and receiving site need approval before the commercial arrangement begins.
Pilot work should compare ALS2 with the current handling route on recovery, reagent consumption, water use, energy demand, labour and residue volume. Those data reveal whether removing one hazardous stream merely creates another. A useful trial also tests mixed EAF dust, not only a convenient laboratory fraction, and checks how feed variability affects stable operation over time.
Safety and environmental performance
Electric arc furnace dust is a respirable particulate, so worker safety must precede any discussion of metal value. Enclosed milling and conveying, grounded equipment, dust monitoring and suitable personal protective equipment form the first layer of control. Alkalis, residual metals and any reagents used in separation add chemical hazards that should be captured in a task-specific risk assessment and Safe Work Australia-aligned procedures.
An environmental case should use measured inputs and outputs rather than broad labels. Operators need data on air emissions, water consumption, wastewater chemistry and the final fate of solid residues. Acidless separation can reduce dependence on corrosive acids and acid-neutralisation salts, yet it cannot guarantee that residues are non-hazardous. TCLP or equivalent leaching tests, together with Australian classification criteria, determine where the remaining material can lawfully go.
Claims about circularity also need boundaries. Recovering metal is valuable, but the recovered fraction must re-enter a controlled supply chain and the residual stream must be tracked to a verified endpoint. Monitoring should cover off-gas, wash water and dust returned from the plant. This evidence gives regulators, workers and neighbouring communities a defensible account of performance.
Compact plants for Australian operations
Compact plants could suit the dispersed nature of Australian scrap processing. A steelworks at Port Kembla or Whyalla already concentrates furnace operations, while metal recyclers around Sydney, Melbourne, Brisbane and Perth may need small urban recovery modules. Locating separation close to the dust reduces the cost and exposure of moving a fine, potentially hazardous residue across long distances.
Compact does not mean exempt from industrial controls. Foundations, ventilation, power, emergency access and hazardous-area requirements can constrain a small footprint. Modules should be designed for Australian summer heat, variable humidity and local maintenance capabilities. Containerised equipment can shorten construction, but it must still meet Australian standards and be supported by technicians who understand both steel plant operations and the separation process.
The operating model may be better as a regional hub than as a plant for every furnace. Trucks could deliver dust to a centre equipped for density testing, blending, separation and residue consolidation, subject to transport approvals. Alternatively, a steelworks could install a dedicated skid. Both options should be compared using logistics, staff exposure, utility connections, recovery credits and the value of each separated product.
Market conditions and regulatory fit
Demand for recovered metals exists, but its scale should not be overstated. Australia’s steel sector already relies heavily on scrap-based electric arc furnace routes, while electronics, vehicles and renewable-energy equipment create continuing WEEE streams. Household habits influence the latter: as Australians upgrade phones and laptops regularly, old devices and loose lithium batteries are still sometimes left in drawers or placed in general waste. Convenient, clearly advertised take-back points are essential.
The market case combines local security of supply with global critical-minerals demand. Copper is important to wiring, motors and grid equipment; zinc supports galvanising; and trace precious metals can have value when present at sufficient grade. Because Australia exports much of its containerised scrap while importing refined metal products, domestic recovery can reduce exposure to volatile prices and long shipping chains. A business case should use conservative payability assumptions for every output.
Regulation is layered rather than centred on one national approval. The Commonwealth Environment Protection Act 1999 and National Pollutant Inventory provisions may apply, as do state environmental licences, waste classifications, transport rules and Safe Work requirements. The National Waste Policy and state e-waste programs shape the broader market, including producer responsibility and collection. For an industrial dust project, the operator should obtain a site-specific legal opinion covering classification, residues, emissions, transport and any beneficial-use claim.
A practical path to circular metals
A sensible deployment begins with three linked decisions. First, obtain a full campaign of site samples and establish what the dust contains. Second, run a comparative pilot with ALS2 and the existing disposal route, measuring metal recovery, worker exposure, utility use and residue quality. Third, build a commercial and regulatory model around the actual outputs. This sequence limits capital exposure while producing the evidence needed for lenders, partners and regulators.
Steelmakers and recyclers should contact the ALS2Project team, agree the sampling and pilot protocol, and select a site that can provide representative dust under safe transport controls. The immediate action is to turn the question of whether furnace dust can be treated into a measured local trial with agreed standards for metal recovery, worker safety, utility use and residue quality.