Melting and stone production using MSW incinerated ash

Area of Science:

• Environmental Engineering
• Materials Science
• Waste Management

Background:

• Municipal solid waste (MSW) incineration in Japan generates ash, increasing landfill burden and environmental concerns.
• Melted slag from incineration has limited use in civil engineering due to low strength.
• A novel technology was developed to crystallize melted slag into higher-strength stones.

Purpose of the Study:

• To develop and demonstrate a technology for converting MSW incinerator ash into high-strength construction materials.
• To assess the environmental safety and civil engineering applicability of the produced stones.
• To confirm the long-term operational stability and performance of the demonstration plant.

Main Methods:

• Construction and operation of a 4.8 tons/day demonstration plant for melting ash and producing stones.
• Treatment of over 750 tons of MSW incinerated ash.
• Analysis of dioxin decomposition, heavy metal leaching, and physical properties of produced stones according to Japanese standards.

Main Results:

• Stable plant operation confirmed, producing high-quality stones from MSW ash.
• Over 99.9% of dioxins were decomposed, with concentrations below environmental standards in the stones.
• Hazardous heavy metal leaching met environmental standards, confirming safe application.
• Produced stones met Japanese Industrial Standards for aggregate and were successfully used in permeable pavement and asphalt.

Conclusions:

• The developed technology enables stable, safe, and effective utilization of MSW incinerator ash as construction material.
• The produced stones offer a sustainable solution for MSW management, reducing landfill needs and environmental impact.
• Commercial-scale application of these stones in civil engineering projects is feasible and demonstrated.