Comparative Analysis of Hazardous Air Pollutant Emissions of Casting Materials Measured in Analytical Pyrolysis and Conventional Metal Pouring Emission Tests

Demonstration-scale metal pouring emission tests and bench-scale Curie-point pyrolysis emission tests were conducted to identify and quantify the hazardous air pollutant (HAP) emissions of five kinds of casting materials, namely, bituminous coal, cellulose, conventional phenolic urethane binder (PUB), naphthalene-depleted PUB, and a collagen-based binder. For a given casting material, the major HAP species generated in Curie-point pyrolysis were essentially the same as those generated in demonstration-scale metal pouring. The 8-10 HAP species identified in the Curie-point pyrolysis tests comprised 65-98% (by weight) of the total HAP emissions quantified in the demonstration-scale pouring emission tests. Furthermore, with these two protocols, we appraised the relative emission changes that would be associated with (a) replacing conventional PUB with collagen-based binder, (b) replacing conventional PUB with naphthalene-depleted PUB, and (c) replacing bituminous coal with cellulose for making sand molds or cores in the casting process. The relative emission changes associated with the use of alternative casting materials exhibited similar trends for most of the major HAP species in the demonstration-scale pouring and Curie-point pyrolysis emission tests. The results indicated that Curie-point pyrolysis emission test could be employed as a convenient and cost-effective screening tool to identify the major HAP species and to compare the relative HAP emission levels for various casting materials.