The Handling and Disposal of Reactive Metals
By: Kevin Mouser

The Department of Environmental Health and Safety (EHS) recently assisted in the investigation of a near trash can fire which occurred in a campus laboratory. In this particular incident, a researcher had recently completed a procedure where powdered zinc was used as reducing agent. Not all of the zinc was utilized or reacted during the course of the procedure. The remaining powdered zinc was discarded in a nearby trash can which also contained disposable gloves and other general waste items. As the trash can was located close to a nearby sink routinely used for hand washing, it contained several damp paper towels.

The zinc dust now located in a damp environment began to heat spontaneously in reaction to the moisture contained within the paper towels. Surrounding paper toweling and disposable gloves were heated to the point of smoldering as a result of the reaction. Fortunately, the laboratory occupants observed smoke being generated from the ongoing reaction and promptly doused the waste receptacle with the laboratory fire extinguisher – thereby averting a fire within the laboratory.

This incident certainly serves to remind us that several metal shavings or metal dusts can be spontaneously reactive with moisture or water. Water reactive metals commonly found in campus laboratories include:

• Lithium
• Sodium
• Potassium (Lithium, sodium and potassium are part of the alkali metal family and most commonly found as solid chunks stored under oil or kerosene).
• Magnesium
• Zirconium
• Titanium
• Aluminum
• Zinc

Any of these metals can readily react aggressively with water under the correct conditions. The reaction may also readily release hydrogen gas creating a potentially explosive atmosphere as the reaction may generate adequate heat to cause the hydrogen gas to be self-igniting –thereby causing a fire or explosion.

Any unreacted portions of these metals should be referred to EHS for disposal. If you have not had the opportunity to use our on-line manifest form, please give it a try. It is quick, convenient and will save you entry time in the future. The on-line manifest form can be found at:
http://www.ehs.iupui.edu/ehs/environment_manifestForm.asp