A method for concentrating precious metals contained in the leaching
residue discharged from a copper hydrometallurgical process by removing
pyrite from the residue. A method for concentrating precious metals in
the leaching residue containing pyrite, elementary sulfur, precious
metals and gangue, discharged from a copper hydrometallurgical process
which comprises steps of leaching in an acidic, aqueous solution,
reducing the copper-containing leaching liquor and electrolysis for
copper recovery to treat copper sulfide ores, comprising (1) pyrolysis
step in which the leaching residue is thermally treated at 550.degree. C.
or higher in a non-oxidative atmosphere, to produce the calcined ore
containing pyrrhotite, precious metals and gangue, and (2) a re-leaching
step in which the calcined ore is re-leached in an acidic, aqueous
solution, to be separated into the re-leaching residue and iron-leached
liquor, the former containing elementary sulfur, precious metals and
gangue.