DC Plasma Furnace for Fly Ash Treatment

I. Core Principle

• Heat Source Mechanism: Adopts DC arc discharge to form a stable, directional and high-energy-density plasma arc column between electrodes, with a temperature up to 1500–1700°C (3000°C for plasma torch type), much higher than that of traditional furnaces.
• Treatment Process:
  1. Fly ash is completely melted at high temperature, and organic matter is completely pyrolyzed and gasified (no secondary pollution).
  2. Heavy metals are solidified in the glassy network structure formed by SiO₂ with an extremely low leaching rate, achieving permanent harmlessness.
  3. Molten slag is rapidly cooled to form glass body, which can be recycled; valuable metals such as iron and aluminum are recovered at the same time.
  
  

II. Equipment Structure (Typical Configuration)

• Furnace Body: Lined with refractory materials resistant to high temperature and erosion, equipped with intelligent temperature control and anti-erosion systems.
• Electrode System: DC graphite electrodes (or hollow electrodes), adjustable up and down to ensure stable arc and low loss.
• Plasma Generator: DC arc torch / transferred arc to provide stable heat source.
• Feeding / Slag Discharge: Continuous / semi-continuous feeding; molten slag overflows and is discharged, then water-quenched into glass body.
• Flue Gas / Tail Gas: Secondary combustion of high-temperature flue gas + rapid cooling + purification to meet emission standards.

III. Process Flow (Fly Ash Treatment)

1. Pretreatment: Fly ash + silicon-based / calcium-based additives (adjust melting point and vitrification effect) → mixing → granulation (3–10mm).
2. Feeding: Quantitative feeding into DC plasma furnace.
3. Melting and Vitrification: High-temperature melting at 1500–1700°C, decomposition of organic matter and solidification of heavy metals.
4. Slag Discharge and Cooling: Molten slag overflow → water quenching → glassy slag (non-toxic, recyclable).
5. Flue Gas Purification: High-temperature flue gas → secondary combustion → rapid cooling → dust removal → desulfurization and denitrification → discharge up to standard.
6. Recycling: Glass body used for rock wool, glass-ceramics, cement admixture, road base materials, etc.; recovery of valuable metals.

IV. Technical Advantages (vs. Traditional Processes)

V. Typical Applications and Cases

• Core Applications: Harmless and resource treatment of power plant fly ash, waste incineration fly ash and industrial solid waste.
• Representative Case: 2000KVA DC arc furnace for fly ash melting, with large daily processing capacity per furnace, which can convert fly ash into glass body and recover metals, and has realized industrial application.
• Recycled Products: Rock wool, thermal insulation materials, cement admixtures, road base materials, glass-ceramics, etc.

VI. Key Parameters (For Reference)

• Operating temperature: 1500–1700°C
• Single furnace capacity: Commonly 1000–5000KVA (e.g. 2000KVA)
• Processing capacity: Depends on capacity, daily processing capacity of 2000KVA grade can reach dozens of tons
• Electrode: Graphite electrode (hollow / solid)
• Working gas: Air, nitrogen, argon, etc.

VII. Summary