湿型砂铸造中危险性空气污染物的测试与分析

用分析裂解技术模拟湿型砂铸造过程中湿型砂与煤粉的热解过程,并采用GC-FID/MS等对分析裂解产生的危险性空气污染物(hazardous air pollutant,HAP)进行了分析.研究表明,湿型砂铸造过程中产生的HAP主要是由于湿型砂中的煤粉热解产生的,其主要成分为苯、甲苯、二甲苯、苯酚和萘等.慢速热解时,HAP主要产生在350～700℃.快速热解时,HAP的产率明显高于慢速热解时的产率.通过与实际铸造过程中产生的HAP对比发现,分析裂解与实际铸造过程中产生的HAP成分十分相似.因此,可以采用分析裂解实验获取铸造过程的HAP清单.与传统的采用实际铸造获取HAP清单的方法相比,分析裂解实验可以大幅度降低获取铸造过程HAP清单的检测成本和检测时间.

Study on the Mechanisms of Hazardous Air Pollutant Emissions from Green Sand Casting

Analytic pyrolysis was conducted to simulate the heating conditions that green sand and bituminous coal would experience during metal casting process. The hazardous air pollutant (HAP) emissions from analytical pyrolysis were analyzed by GC-FID/MS. The major components of the HAP emissions included benzene, toluene, xylene (BTX), phenol, and naphthalene. These HAPs were generated from the pyrolysis of bituminous coal that was added as carbonaceous additives in the green sand. During TGA slow pyrolysis, HAPs were mainly generated at 350-700 degrees C. The yield of HAPs increased considerably when the coal was flash pyrolyzed. The HAP emissions from analytical pyrolysis exhibited some similarity in the compositions and distributions with those from actual casting processes. Compared with the conventional actual metal pouring emission tests, analytical pyrolysis techniques offered a fast and cost-effective way to establish the HAP emission inventories of green sand during metal casting.