Updated: July 2002

1. Melting of Sludge

The increasing of sewage sludge has been making the securing of disposal sites difficult, and the sludge disposal has become a big problem. Vortex Melting System was developed to solve such problems, 150 ton/day scale plant is operating.
As the sludge is heated up to 1,200-1,400ºC, the organic matter burns, while the inorganic matter melts.
The sludge melting process has the following merits in comparison with incineration process:
1) Recycling: Slag can be used as a construction material.
2) Stabilization: Heavy metals contained in the sludge are sealed in the slag without leaching.
3) Volume reduction: The volume of slag is ½-1/3 of incinerated ash.

2. Features

1) Because of high loading burning, the melter is compact.
2) The strong vortex flow allows to keep the higher slag recovery ratio.
3) The simple configuration makes the operation and maintenance easy.
4) Because of low air ratio burning, low NOx operation is possible.

3. Configuration

The body of the melter consists of a small vertical pre-combustion furnace and a cylindrical main combustion furnace. The sludge, dried to a moisture content less than 10% and crushed to a particle size less than 1000µm, are blown into the pre-combustion furnace with the pre-heated air. After being dried and thermal cracked, the sludge burns and inorganic matter is melted to flow down along the furnace wall.
The Vortex Melting System is a suitable system using the advanced technology for recycling of sludge. An energy-saving type using oxygen, called the Slag Bath Oxygen Melting Furnace (SBOM) has been developed to melt incinerated ash. And the crystallization of slag can spread the applications of slag.