Metals in the kiln
Most metals can be used in the kiln without damage to the elements. In fact, I can not think of one that will damage the elements.
However, silver stains the shelves it touches. This stain transfers to the next piece of glass you put over the shelf. So separate shelves are required for silver metal and stains, or 3mm thick fibre paper to prevent staining of the shelf.
Other than silver stain, the metal residue will not affect the glass.
One more caveat though. Zinc and possibly other metals give off toxic fumes. These fumes are dangerous to YOUR health, not the kiln’s.