Understanding Emission Characteristics of a Foundry Sand Binder

摘要

Emissions from the casting process, primarily hazardous air pollutants (HAP's) and volatile organic compounds (VOC's), can cause long-term health issues for foundry workers when emitted into the workplace environment. In this study, thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC) connected to a mass spectrometer (MS) provided a way to monitor the emission rate of these compounds in addition to light gases during the decomposition of phenolic urethane. The experiment utilized phenolic urethane discs heated to 1200°C at a rate of 10°C per minute under an oxidizing (oxygen), reducing (carbon monoxide) and neutral (nitrogen) atmosphere. A neutral atmosphere was observed to produce the highest amounts of HAP's and VOC's. An oxidizing and reducing atmosphere decreased most of the HAP and VOC emission compounds with an increase in production of lighter gases such as hydrogen, water, and propene. When comparing reducing and oxidizing atmospheres, benzene, toluene, and xylene emission compounds were shifted to higher temperatures when exposed to a reducing atmosphere without a noticeable decrease in total production. An oxidizing atmosphere contributed to higher production of lighter gases at temperatures above 600°C (1110℉), surmised as the oxidization of HAP's, VOC's and carbon residue. The research work demonstrated the atmosphere has a significant influence on the amount and temperature range where benzene, toluene, and xylene are emitted during the combustion of phenolic urethane, providing for the foundry community an experimental technique to accurately replicate the mold environment during the casting process.