PREVENTING MOLTEN METAL EXPLOSIONS RELATED TO SKIM TOOLS AND SALT

摘要

In 2003, Alcoa Inc. experienced a number of molten aluminum explosions that were associated with hand skim tools used for cleaning in-line metal treatment units. These explosions were investigated and the incidents appeared to be related to the residual skim and dross on the tools from previous skimming operations. Visual observations indicated high moisture content on the skim left on the tools once they cooled to room temperature. Analysis of the dross confirmed that it contained varying amounts of magnesium chloride salts, which are highly hygroscopic at room temperature. Testing was performed analyzing the skim and investigating moisture pick-up and release during cooling and heating cycles. Based upon this analysis, procedural and equipment modifications were made to minimize the risk of further explosions.