The over-pressurization of a laboratory ball mill reactor designed for operation under slightly elevated pressures resulted in a serious injury. The apparatus had been routinely operated under argon and hydrogen pressures of 5-10 atmospheres for nearly two years. The apparatus had not been tested for operation at pressures greater than 10 atm.

A visiting intern, frustrated in attempts to hydrogenate magnesium silicide through ball milling in the previously noted pressure range, attempted to perform the operation at higher pressures. The approximately 70-ml reactor was loaded in a glove box with 0.5 g of magnesium silicide and six milling balls. Upon pressurization to 80 atmospheres, a 270-degree rupture occurred around the perimeter of the reactor. The blow-out of the reactor resulted in a very loud noise and the contents of the ball mill were thrown all over the lab. Since the pressure inlet valve is situated near the top to the ball mill, the intern's hand was in the path of the lift-off of the top of the reactor and the person received a deep, 3-cm cut on the palm of the right hand.

Several other laboratory workers heard the noise and immediately administered first-aid. Security, paramedic and environmental health and safety personnel quickly arrived and took charge of the situation. The intern was taken by ambulance to a local hospital, where the cut was closed with about a dozen stitches. The intern was discharged from the hospital immediately after treatment.

Incident Date
Aug 01, 2006
  • Laboratory Equipment
  • Ball Mill
  • Laboratory Equipment
  • Reactor
Damage and Injuries
Probable Cause
When Incident Discovered
Lessons Learned

The visiting intern had several years of experience in research projects and tasks that were similar to those in progress at this laboratory. This led to the incorrect assumption that formal introductory training for this laboratory was unnecessary. Steps should always be taken to ensure that anyone working in an unfamiliar laboratory setting is properly trained.

It is important to have written operating procedures for the use of laboratory-scale equipment involving hazards or risks of this nature. Operating procedures should also document any equipment parameter limits. Such procedures should be reviewed with all personnel as part of their laboratory training before they perform any experiments.

More information on management of change can be found in the Lessons Learned Corner and also in the Hydrogen Safety Best Practices Manual.