Disposing Metal Powder


Insights on whether or not metal powder (10-100 micron size) can be disposed of in the normal trash in San Mateo, California.

Early Findings

  • Under the RCRA hazardous waste rules, scrap metals must be recycled through Waste Management. Metals in powder \\form may pose a higher risk than metals like wires, pins, and pellets.
  • Metal powders may be self-reactive or flammable. Metal powders only meet the definition of scrap metal if they have been "agglomerated in such a way that the agglomerated powders physical resemble other types of scrap metal (i.e., bits and pieces of metal parts).”
  • Metal sludge, dusts, and "fine powders with a diameter of less than 100 microns (about the diameter of a human hair), and semi-solids are potentially hazardous wastes."
  • In San Mateo, scrap metals should never be discarded in the trash. Typically, metal powders must be "placed in a metal container, sealed tightly, and labeled with a red Hazardous Waste tag prior to disposal."
  • Although San Mateo does not explicitly state on its website that metal powders must not be disposed via a normal waste, these powders may be hazardous - depending on what chemicals they were made with - and should generally not be disposed normally.

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