In some oil refineries, the production of petroleum coke can be a responsible and environmentally-friendly recycling method that makes best use of hydrocarbons left over from other processes. Safety and health issues are present in any industrial process. Coking is a process that generates gaseous and fine particulate emissions. PM can result in adverse respiratory health effects including decrements in lung function. In addition, coke may release toxic metals or trace elements which can impact the environment.
Material handling can be dangerous due to the possibility of an explosion of combustible powder or dust. As petcoke is high in carbon content and contains only a tiny amount of volatiles (which are flammable), it may spontaneously explode or ignite if heated or exposed with sparks. The deflagration or coke fire can result in serious injury and significant damage to property, equipment and buildings.
To mitigate this risk, OSHA's National Emphasis Program on Combustible Dust requires that facilities use administrative controls such as housekeeping, fire prevention, and ventilation with ignition and explosion/deflagration suppression systems when a combustible dust layer is greater than 1/32 of an inch (about the thickness of a paper clip). Those same measures are also required for silos where the coke is stored until it is loaded on ocean-going vessels.
The finely-divided, combustible material is expelled as dust by the material handlers who transport the coke to the storage area and the delivery point. Total Safety used an optical particle counter to measure the amount of airborne dust particles that were emitted from bulk coke as it was transported from storage to the transportation points. The respirable range of size was more than 65% for the bulk coke product.
Calcined petroleum is not only an excellent energy source but also a valuable industrial raw material. Cement, bricks, or tires can be made from it. Many electric power plants use it as an alternative to coal because of its lower carbon dioxide emissions per unit energy.
The toxicity of Petcoke, despite its wide use, is unknown. A number of occupational epidemiology studies have evaluated health risks among coke oven workers, but results have been inconsistent and confounded by other exposures and other factors. A few ecological and toxicological studies have been performed, and no toxicity was observed for fresh or aged coke in water tests with an alga, crustaceans (Daphnia magna and Thamnocephalus platyrurus), a rotifer, and a photobacterium. Mixed results have been found in mutagenicity testing on green and aged coke.
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