Sulfur Dust Explosions in Fertilizer Retail Facilities

Source: The Fertilizer Institute, The Sulfur Institute and Agricultural Retailers Association

Sulfur is an important plant nutrient. Since the passage of the Clean Air Act, the amount of atmospheric deposition of sulfur has dropped across the United States. To compensate for the reduced atmospheric deposition farmers, and their agricultural retailers, are increasingly adding sulfur containing fertilizers to their crops.

The Agricultural Retailers Association (ARA), The Fertilizer Institute (TFI), and The Sulphur Institute (TSI) have become aware of incidents where fertilizer products containing sulfur have flared-up while being blended or handled at fertilizer retail facilities. Once sulphur dust becomes airborne it tends to remain suspended due to the development of surface charges which cause the particles to repel each other. In order to manage this risk, it is important to understand the conditions under which a dust explosion can occur with any combustible material, such as grain, flour, confectionary sugar, etc. This memo is to advise fertilizer retailers of potential to create sulfur dust during blending and handling operations, which could lead to sulfur dust flare-ups if not handled properly.

The National Fire Protection Association Standard 655 (NFPA 655), Standard for Prevention of Sulfur Fires and Explosions (2012) addresses prevention of sulfur fires and explosions. As noted in the standard sulfur dust has a low ignition point of 190oC and the dust clouds are readily ignited by weak frictional sparks. Dusts containing 25% or more of elemental sulfur may have a propensity for flare-ups. Sulfur has excellent electrical insulation properties and under certain conditions can pick up static electricity, which, when discharged could cause a spark and ignite a dust cloud. Due to potential dangers when mechanically blending sulfur, it is advisable to review your safety and housekeeping procedures and ensure that equipment and facilities are maintained to minimize risk of sulfur dust incidents.

The NFPA 655 Standard is available for purchase online. Attached is a fact sheet on sulfur prepared by the International Plant Nutrition Institute, and a fact sheet on combustible dust prepared by the Occupational Safety and Health Administration.

If you have any questions, please do not hesitate to contact either Wade Foster with TFI via email at wfoster@tfi.org, Kyle Liske with ARA via email at kyle@aradc.com, or Craig Jorgenson TSI via email at cjorgenson@sulphurinstitute.org.

Click here for a fact sheet from the Occupational Safety and Health Administration on combustible dust explosions.

Click here for a fact sheet from the International Plant Nutrient Institute on sulfur.