Thermal plasma processing of high temperature insulation wools

Area of Science:

• Materials Science
• Environmental Engineering
• Plasma Physics

Background:

• High temperature insulation wool (HTIW) wastes, including alkaline earth silicate wools (AESW) and alumino silicate wools (ASW), are generated in large volumes from construction and demolition.
• These wastes are difficult to recycle and pose environmental and health hazards.
• Current mitigation and reuse strategies for HTIW wastes are underexplored.

Purpose of the Study:

• To investigate the air plasma mitigation of four common types of HTIW wastes: fresh rock wool, waste rock wool, waste stone wool, and waste ceramic wool.
• To explore a novel, single-step dry process for waste valorization.
• To characterize the resulting vitreous product and discuss its potential applications.

Main Methods:

• Utilized an air plasma torch, leveraging ambient air for plasma generation.
• Employed two-color pyrometry for in-situ investigation of the thermal field in the melting zone.
• Characterized the solidified end product using X-ray diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray Analysis, Energy Dispersive X-ray Fluorescence Spectroscopy, and Neutron Activation Analysis.

Main Results:

• Demonstrated a fast, efficient, and economic single-step dry process for HTIW waste mitigation.
• Successfully converted diverse HTIW wastes into a homogeneous vitreous material.
• The process utilizes the high enthalpy and reactive species present in air plasma for effective material transformation.

Conclusions:

• Air plasma mitigation offers a unique and viable solution for recycling problematic HTIW wastes.
• The resulting vitreous product shows potential for valorization, with its properties determined by the elemental composition of the original waste.
• This study provides a foundation for further research into the application of plasma technology for industrial waste management.