PURPOSE: To separate noble-metal elements with simplified equipment by adding a reducing agent to an acidic soln. contg. gold and platinum-group elements to deposit gold and Pd, adding a metallic reducing agent to the filtrate to deposit Rh, and separating the Rh from platinum.
CONSTITUTION: The hydrochloric aicd-acidified deposit formed in the refining of copper, etc., consisting essentially of silver chloride, and contg. concentrated noble-metal elements such as gold and platinum-group elements is leached by aq. ammonia, the residue is further leached by aqua regia, the leachates are adjusted to ≤pH4, hence silver chloride is deposited and removed, and an acidic soln. contg. gold and platinum-group elements is obtained. A reducing agent (hydroxylammonium chloride, etc.) is added to the soln. to deposit and separate gold and Pd, a metallic reducing agent (Zn sheet, etc.) is added to the filtrate to reduce and deposit Rh, and the Rh is separated from platinum in the filtrate. By this method, noble-metal elements are efficiently separated from the deposit.
ISHIWATARI MASAHARU
KIMURA ETSUJI
