Hydrogen Sulfide Exposure from Molten Sulfur - A Forgotten Hazard?

摘要

Molten sulfur is one of the most frequently transported hazardous materials (hazmat) in North America. Molten sulfur is typically transported at an elevated temperature by rail tank cars or over-the-road tank trailers as a Class 9 "Miscellaneous Hazardous Material" under the identification number NA2448. Perhaps the most prominent hazard of molten sulfur is that it is shipped at an elevated temperature, which can cause thermal burn injuries. A less obvious hazard is the potential release of hydrogen sulfide (H2S), a highly toxic gas. In this paper we first summarize the key features of the H2S-molten sulfur equilibrium that are relevant to this hazard. Then we address the relative risk of H2S exposure from an analysis of molten sulfur incident release statistics. Next, we discuss a few case studies in which vented H2S gas from molten sulfur led to unexpected consequences for handling personnel. We close our discussion with suggestions for how to possibly prevent H2S exposure through a combination of engineering controls, operating procedures for both loading and unloading operations, air monitoring, and personal protection equipment.