Rocktec partnered with Winstone Aggregates to design, build, and install a high-performance slag processing plant in New Zealand. This purpose-built system was developed to crush, screen, and wash electric arc furnace (EAF) slag—turning steelmaking by-product into reusable, specification-compliant aggregate.
Project Overview: Full EAF Slag Recovery System
- Client: Winstone Aggregates
- Location: New Zealand
- Industry: Aggregates / Metal Recovery
- Scope: Design, build, and installation of complete slag processing plant
The Challenge: Transforming EAF Slag into Usable Aggregate
Winstone Aggregates needed a slag processing plant capable of handling unrefined EAF slag and work debris. The system had to deliver reliable output across multiple slag grades that meet TNZ M/6 specifications. Furthermore, it had to withstand the abrasive nature of slag while maintaining efficient throughput and reducing downtime.
Rocktec’s Solution: A Durable, Multi-Stage Processing Plant
To meet the client’s requirements, Rocktec developed an integrated processing solution that combined strength, flexibility, and efficiency. The system included:
- A refurbished vibrating plate feeder for steady material flow
- A Trio jaw crusher and granulator to reduce slag size
- A refurbished VSI for improved shaping and final sizing
- Rocktec 12’ x 5’ Heavy Duty Double Deck Screen for accurate mid-stage classification
- Rocktec 10’ x 5’ Heavy Duty Triple Deck Screen for final grading
- Conveyor systems to connect all stages of processing
- Precast concrete bunkers that supported the screens while storing graded output
As a result, the plant was able to produce multiple slag grades including EAF grade 2, 3, 4, B5, and pap5—ready for use in roading and civil infrastructure.
Implementation Process: From Concept to Commissioning
- Design: Rocktec collaborated with Winstone Aggregates to define performance targets, flow paths, and output grades.
- Fabrication: New components and refurbished machines were prepared and tested in Rocktec’s facility before delivery.
- Installation: The team installed the plant on-site and integrated it seamlessly with the existing infrastructure.
Results and Benefits
- Grade Compliance: The plant outputs consistent, TNZ M/6-compliant slag for infrastructure projects.
- Improved Efficiency: An optimised layout and robust components ensure reliable performance with minimal maintenance.
- Dual-Purpose Design: Concrete bunkers serve as both product storage and screen support structures.
- Cost Control: Using refurbished components kept capital costs down without compromising durability.
Conclusion: Building Smarter Slag Solutions
This slag processing plant highlights Rocktec’s ability to blend recycled equipment with modern engineering and deliver results. Winstone Aggregates now has a durable, high-output system that turns slag into road-ready aggregate—helping them meet demand while improving sustainability.
Want to Learn More?
To discover more about EAF slag recycling and screening innovation, visit the Australian Bulk Handling Review.
If you’re planning a slag processing plant or need a tailored aggregate recovery system, contact Rocktec to start your project.