Project Background
Municipal solid waste incineration produces fly ash equal to roughly 3-5% of total waste volume. Fly ash contains heavy metals and dioxins, so landfill disposal is both costly and environmentally risky. Shaanxi Chengda Industrial Furnace Manufacturing Co., Ltd. designed and built China's first large-scale fly ash to rock wool electric furnace for a thermal power plant in Zhuji, Zhejiang.
The Challenge
Turning a hazardous waste into a construction insulation product requires three things at once: complete destruction of dioxins, removal of heavy metals, and a melt quality good enough to form consistent rock wool fibre. Traditional coke-fired cupolas cannot do this reliably.
Technical Solution
| System | Design |
|---|---|
| Melting | Electric heating furnace, 7500kVA cold slag rock wool electric furnace |
| Raw material | Fly ash with basalt, slag and additives |
| Process route | Batching, automatic weighing, in-furnace smelting, centrifugal fibre forming, curing |
| Dioxin control | Complete high-temperature destruction of dioxins |
| Heavy metals | Targeted removal system to make the product non-hazardous |
Key Advantages
- High-value utilisation - one tonne of fly ash yields roughly one tonne of rock wool, with output value exceeding RMB 2,000 per tonne of ash
- Energy breakthrough - comprehensive energy consumption per tonne is more than 40% lower than a coke cupola, while melting efficiency is about double
- Precise control - automatic weighing plus furnace temperature field optimisation keeps melt quality stable and raises fibre forming rate
- Environmental compliance - lower flue gas volume, reduced carbon emissions and destruction of toxic organics
Commissioning and Results
The 7500kVA cold slag electric furnace was installed and cold commissioned within two months, with the customer's project team confirming completion ahead of schedule. After entering hot production, the furnace ran continuously without fault, delivering stable output and consistent fibre quality. The project has become a reference case for "zero-waste city" programmes and for the dual-carbon in the waste-to-materials sector.
Conclusion
For incineration plants, this furnace turns a disposal liability into a product line. For rock wool producers, it offers an electric melting route that is independent of coke prices and far cleaner at the stack.
Delivery and Training
Chengda supplied the furnace proper, automatic batching and weighing system, off-gas treatment interface, control system and installation drawings, and trained the plant team on start-up, melt control, fibre forming and emergency procedures.
What Comes Next
Following the first successful line, the same electric melting route can be applied to other waste streams, including slag and contaminated mineral residues. Chengda continues to work with the plant on capacity expansion and on improving fibre quality through tighter melt temperature control.