Nonmetallic Element Fuels

Properties of the Nonmetallic Elements Used as Fuels in High-Energy Mixtures 

Element Symbol Atomic Weight Melting Point, oca Boiling Point, oca Heat of Combustion, kcal/grambr Combustion Product Crams of Fuel Consumed per Gram of O 

Shidlovskiy, Principles of Pyrotechnics, 3rd ed., Moscow, 1964. (Translated by Foreign Technology Division, Wright-Patterson Air Force Base, OH, 1974.) 

The use of sulfur as a fuel in pyrotechnic compositions dates back over one thousand years, and the material remains a widely used component today in black powder, colored smoke mixtures, and firework compositions. For pyrotechnic purposes, the material termed flour of sulfur that has been crystallized from molten sulfur is preferred. Sulfur purified by sublimination—termed flowers of sulfur—often contains significant amounts of oxidized, acidic impurities and can be quite hazardous in high-energy mixtures, especially those containing a chlorate oxidizer.  

When present in large excess, sulfur may volatilize out of the burning mixture as a yellowish white smoke. A 1 1 ratio of potassium nitrate and sulfur makes a respectable smoke composition employing this behavior. 

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Whereas acid-base reactions can be characterized as proton-transfer processes, the class of reactions called oxidation-reduction, or redox, reactions are considered electron-transfer reactions. Oxidation-reduction reactions are very much a part of the world around us. They range from the burning of fossil fuels to the action of household bleach. Additionally, most metallic and nonmetallic elements are obtained from their ores by the process of oxidation or reduction. 

A variety of materials can be used as fuels in energetic mixtures, and the choice of material will depend on a variety of factors—the amount of heat output required, ignitability, rate of heat release needed, cost of the materials, stability of the fuel and fuel-oxidizer pair, and amount of gaseous product desired. Fuels can be divided into three main categories metals, nonmetallic elements, and organic compounds. 

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