VITRIFICATION OF LEAD-BASED PAINT USING THERMAL SPRAY

摘要

Lead-based paint (LBP) primers have been used to protect steel structures from corrosion. Abrasive blasting is currently used to remove old LBP. During abrasive blasting a containment structure is required to keep the hazardous lead dust from contaminating air, soil, or water. A thermal spray vitrification (TSV) process to remove LBP was developed. Dried glass powder is melted in the high temperature flame of the thermal spray torch. When the glass strikes the substrate it is molten and reacts with the paint on the substrate. The organic components of the paint are pyrolyzed, while the lead ions are trapped on the surface of glass. The quenching stresses in the glass cause the glass to crack and spall off the substrate. The crumbled glass fragments can be collected and remelted, immobilizing the lead ions within the glass network, thereby preventing leaching. The resulting glass can be disposed of as non-hazardous waste. The process is dust-free, eliminating the need for containment. The volume of residue waste is less than for abrasive blasting and is non-hazardous. The concept and techniques of using the thermal spray vitrification process for the removal and the containment of lead from a section of a bridge containing lead-based paint have been successfully demonstrated.